IMPROVED SOLDER AND METHOD FOR PRODUCING HIGH PURITY LEAD

专利摘要:
Revealed is a metal mixture composition containing lead and tin and comprising by weight at least 10% tin and 40% lead, at least 90% tin and lead together, more lead than tin, from 1-5000 ppm copper, at least 0, 42% antimony, maximum 0.1% of the total chromium, manganese, vanadium, titanium and tungsten, and maximum 0.1% of each of aluminum, nickel, iron and zinc. Also disclosed is a method comprising a pretreatment step for producing this metal mixture composition, followed by a vacuum distillation step in which lead is removed by evaporation and a bottom stream is obtained which comprises at least 0.6% by weight of lead.
公开号:BE1024606B1
申请号:E2017/5681
申请日:2017-09-26
公开日:2018-04-25
发明作者:Koen Govaerts；Pelle Lemmens；Kris Mannaerts；Dirk Goris；Visscher Yves De；Charles Geenen；Bert Coletti
申请人:Metallo Belgium；
IPC主号:

专利说明:

(30) Priority data:
27/09/2016 EP 16190907.2 (73) Holder (s):
METALLO BELGIUM 2340, BEERSE Belgium (72) Inventor (s):
GOVAERTS Koen
2275 WECHELDERZANDE
Belgium
LEMMENS Pelle 2275 POEDERLEE Belgium
MANNAERTS Kris 2290 VORSELAAR Belgium
GORIS Dirk
2340 BEERSE Belgium
THE FISHERMAN Yves 2275 WECHELDERZANDE Belgium
NO Charles 3900 OVERPELLES Belgium
COLETTI Bert
3930ACHEL
Belgium (54) IMPROVED SOLDER AND METHOD FOR PRODUCING LEAD WITH
HIGH PURITY (57) Revealed is a metal mixture composition containing lead and tin and comprising by weight at least 10% tin and 40% lead, at least 90% tin and lead together, more lead than tin, of 1-5000 ppm copper , at least 0.42% antimony, up to 0.1% of the total of chromium, manganese, vanadium, titanium and tungsten, and up to 0.1% of each of aluminum, nickel, iron and zinc. Also disclosed is a method comprising a pre-treatment step for producing this metal mixture composition, followed by a vacuum distillation step in which lead is removed by evaporation and a bottom stream comprising at least 0.6% by weight of lead.
Figure ï
BELGIAN INVENTION PATENT
FPS Economy, K.M.O., Self-employed & Energy
Publication number: 1024606 Filing number: BE2017 / 5681
Intellectual Property Office
International classification: C22C 11/10 B23K 35/26 Date of issue: 25/04/2018
The Minister of Economy,
Having regard to the Paris Convention of 20 March 1883 for the Protection of Industrial Property;
Having regard to the Law of March 28, 1984 on inventive patents, Article 22, for patent applications filed before September 22, 2014;
Having regard to Title 1 Invention Patents of Book XI of the Economic Law Code, Article XI.24, for patent applications filed from September 22, 2014;
Having regard to the Royal Decree of 2 December 1986 on the filing, granting and maintenance of inventive patents, Article 28;
Having regard to the application for an invention patent received by the Intellectual Property Office on 26/09/2017.
Whereas for patent applications that fall within the scope of Title 1, Book XI, of the Code of Economic Law (hereinafter WER), in accordance with Article XI.19, § 4, second paragraph, of the WER, the granted patent will be limited. to the patent claims for which the novelty search report was prepared, when the patent application is the subject of a novelty search report indicating a lack of unity of invention as referred to in paragraph 1, and when the applicant does not limit his filing and does not file a divisional application in accordance with the search report.
Decision:
Article 1
METALLO BELGIUM, Nieuwe Dreef 33, 2340 BEERSE Belgium;
represented by
GEVERS PATENTS, Holidaystraat 5, 1831, DIEGEM;
a Belgian invention patent with a term of 20 years, subject to payment of the annual taxes as referred to in Article XI.48, § 1 of the Code of Economic Law, for: IMPROVED SOLDER AND METHOD FOR PRODUCING HIGH PURITY LEAD.
INVENTOR (S):
GOVAERTS Koen, Lindelaan 7, 2275, WECHELDERZANDE;
LEMMENS Pelle, Beukenlaan 29, 2275, POEDERLEE;
MANNAERTS Kris, Square 13A, 2290, VORSELAAR;
GORIS Dirk, Patrijsstraat 17, 2340, BEERSE;
THE FISHERMAN Yves, Wagemansstraat 64, 2275, WECHELDERZANDE;
NO Charles, Willem II Street 27, 3900, OVERPEL;
COLETTI Bert, Catherine Valley 1, 3930, ACHEL;
PRIORITY:
27/09/2016 EP 16190907.2;
BREAKDOWN:
Split from basic application:
Filing date of the basic application:
Article 2. - This patent is granted without prior investigation into the patentability of the invention, without warranty of the Merit of the invention, nor of the accuracy of its description and at the risk of the applicant (s).
Brussels, 25/04/2018,
With special authorization:
BE2017 / 5681
Improved solder and method for producing high purity lead
Field of the invention
The present invention relates to the production of non-ferrous metals, more specifically tin (Sn) and lead (Pb) in combination with the production of copper (Cu), from primary sources, ie fresh ore, from secondary raw materials, also known as recyclable materials, or from combinations thereof, by Pyrometallurgy. Recyclable materials can be, for example, by-products, waste materials and end-of-life materials. More specifically, the invention relates to an improved solder composition, a metal mixture comprising mainly tin and lead generated as a by-product of copper metal production, and to its preparation and separation by vacuum distillation.
Background of the invention
The materials available as raw materials for the production of non-ferrous metals typically contain a variety of metals. Because the non-ferrous metals in most of their large volume applications must have a high purity, the different metals must be separated from each other in the production process. The non-ferrous metal production processes typically contain at least one and usually a plurality of pyrometallurgical process steps in which metals and metal oxides both exist in the liquid molten state, and the metal oxides can be separated by gravity as a separate and usually lighter liquid slag phase from the molten metal phase. The slag phase is usually removed from the process as a separate stream, and this separation
BE2017 / 5681 can lead to the production of a slag as a by-product of metal production.
The non-ferrous metals can be produced from fresh ore as a starting material, also called primary sources, or from recycled materials, also known as secondary raw materials, or from a combination of these.
The recovery of non-ferrous metals from secondary raw materials has become of paramount importance over the years. The recycling of non-ferrous metals after use has become a major contributor in the industry due to the continued demand for such metals and the decreasing availability of high-quality fresh metal ores. Also the processing of secondary raw materials usually involves the use of pyrometallurgical process steps, such as smelting, which generate a slag as a by-product.
When producing copper by Pyrometallurgy, all tin and / or lead present tends to be oxidized more easily, after which its oxides readily transition to the supernatant slag phase. This slag can be separated from the copper-rich molten metal. The reactive chemical reduction step allows the tin and / or lead in the slag to be subsequently returned to their metal state, and these metals can be separated from the remaining slag as a molten metal mixture rich in tin and / or lead, usually with a significant amount of both. These metal streams generally have a lower melting point than the copper-containing by-products. They are often called "solder" and sometimes "white metal". In addition to tin and lead, these raw solder compositions can contain significant but smaller amounts of other metals, such as copper (Cu), antimony (Sb), arsenic (As), bismuth (Bi), iron (Fe), indium (In), nickel (Ni ), zinc (Zn), aluminum (AI),
BE2017 / 5681 germanium (Ge), tellurium (Te), cobalt (Co), manganese (Mn), selenium (Se), silicon (Si), thallium (Tl), gallium (Ga), and sometimes precious metals, although usually in smaller amounts, such as silver (Ag), gold (Au), platinum (Pt), palladium (Pd), ruthenium (Ru), rhodium (Rh), osmium (Os), and iridium (Ir). The raw solder may also contain non-metallic elements, such as sulfur (S), carbon (C) and oxygen (0).
The raw solder compositions can be used directly commercially depending on their composition, but there is also a need to recover individual components from the solder, in a higher purity form, to make the metal products acceptable for upgrade in their more demanding end uses. Mainly interest remains in the recovery of high purity tin (Sn) from such brazing currents, as well as in the recovery of lead (Pb) in certain higher purity forms.
A known technique for obtaining higher purity metal streams from solder is by vacuum distillation, a technique usually performed under very low pressure, usually no more than 50 Pa absolute, possibly no more than 10-15 Pa, and often only 1 -5 Pa, in combination with relatively high temperatures of at least 900 ° C, often even 1100 ° C. The vacuum distillation of solder type metal mixtures can be carried out batchwise, and such charge vacuum distillation techniques are disclosed in CN101696475, CN104141152, CN101570826, and in Yang et al, "Recycling of metals from waste Sn-based alloys by vacuum separation", Transactions of Nonferrous Metal Society of China, 25 (2015), 1315-1324, Elsevier Science Press. The distillation of metals under vacuum can also be carried out continuously, and the like continuously
BE2017 / 5681 distillation techniques are disclosed in CN102352443, CN104651626 and CN104593614.
The inventors have discovered that the distillation of solder type metals may have operational problems due to the reduced fluidity of the molten liquid metal phase during operation, more specifically when Pb begins to evaporate and its concentration decreases. The problem arises in charge operations, but may become more pronounced in continuous vacuum distillation, where over time, even at high temperatures, insoluble solids can form which can adhere to the distillation equipment, more specifically in sensitive areas such as small openings. which can compromise smooth operation and even block the equipment.
The present invention seeks to overcome or at least alleviate the problem described above and / or make improvements in general.
Summary of the invention
According to the invention, there is provided a metal mixture composition and a method in which the metal mixture acts as an intermediate stream, as defined in any of the accompanying claims.
In one embodiment, the invention provides a metal mixture containing lead (Pb) and tin (Sn), the mixture comprising, by weight, • at least 10% tin (Sn), • at least 45% lead (Pb), • at least 90% tin and lead combined, • more lead than tin, • at least 1 ppm and a maximum of 5000 ppm copper (Cu), • at least 0.42% antimony (Sb), and
BE2017 / 5681 • at least 0.0001% sulfur (S), and • at most 0.1% of the total chromium (Cr), manganese (Mn), vanadium (V), titanium (Ti) and tungsten (W) , • maximum 0.1% aluminum (Al), • maximum 0.1% or nickel (Ni), • maximum 0.1% iron (Fe), and • maximum 0.1% zinc (Zn).
In one embodiment, the invention provides a method of separating by distilling the metal mixture of the present invention comprising the step of pretreating a liquid molten metal feed composition,
a) the feed composition containing substantial portions of tin and lead and comprising at least 0.16 wt% and optionally at most 10 wt% of the total chromium (Cr), manganese (Mn), vanadium (V), titanium (Ti ), tungsten (W), copper (Cu), nickel (Ni), iron (Fe), aluminum (AI) and / or zinc (Zn), the feed composition being available at a temperature of at least 500 ° C, the pretreatment step comprising the steps of:
b) cooling the feed composition to a temperature of up to 825 ° C to produce a bath containing a first supernatant scratch gravitated to a first liquid molten metal phase,
c) adding an alkali metal and / or an alkaline earth metal, or a chemical compound comprising an alkali metal and / or an alkaline earth metal, to the first liquid molten metal phase to form a bath containing a second
BE2017 / 5681 Gravity-induced supernatant scratch on top of a second liquid molten metal phase, and
d) removing the second scratch from the second liquid molten metal phase, wherein the liquid molten metal phase obtained as a product of the pretreatment forms the metal mixture according to the present invention, the method further comprising the step of subjecting the metal mixture to a distillation step in which lead (Pb) is removed from the metal mixture by evaporation and a bottom product is obtained which comprises at least 0.6% by weight of lead.
The inventors have determined that specific metals in the feed composition are capable, under vacuum distillation conditions suitable for evaporating lead from a mixture comprising tin, to form intermetallic compounds between at least two of these specific metals and / or intermetallic compounds of at least one of the specific metals with tin. The inventors have found that many of these intermetallic compounds have a much higher melting point than the temperature of the mixture in which they are formed. The inventors have therefore determined that these high melting point intermetallic compounds can come out of solution and form solids. These solids can remain suspended in the liquid metal, which can reduce the flowability of the mixture, such as by increasing the viscosity of the liquid mixture. This in itself can prevent smooth operation of the distillation equipment, such as by slowing the flow of liquid metals, reducing the capacity of the equipment and thus having to operate the equipment with reduced throughput. The solids can also adhere and / or attach
BE2017 / 5681 to the distillation equipment, which creates a risk of reduced or even hindered operation of the distillation equipment, eg by clogging important throughputs for the process flows. The described phenomenon may even require shutdown of the equipment to open the equipment or replace the affected equipment items.
The inventors have found that the tendency to form such intermetallic compounds increases at a certain temperature when the lead content in the liquid metal mixture is reduced. The inventors have determined that the risk of intermetallic compound formation therefore increases as the molten feed mixture passes from the inlet of the distillation equipment to the outlet of the bottoms, due to the evaporation of lead from the liquid mixture flowing through the distillation equipment.
The inventors have further found that the tendency to form such intermetallic compounds increases with a decrease in the temperature of the molten liquid metal phase. For example, the inventors have observed that the feed entering the vacuum distillation device may have a lower temperature than the Sn-enriched liquid product leaving the distillation equipment. The inventors have thus determined that the deleterious effects of the intermetallic compounds may be more pronounced at lower temperatures. Applicants believe that because of this, the inlet section of the distillation equipment may be particularly susceptible to the above-described problems caused by the intermetallic compounds.
The inventors have further found that continuous distillation of lead from tin is even more susceptible to the problem addressed by the present invention. The inventors believe
BE2017 / 5681 that this is at least in part because a continuous distillation operation provides more time for a gradual build-up of solids that come out of the solution and can adhere to the equipment. Thus, in a continuous operation, the solids can pile up and create greater problems than in cargo operations. In addition, the liquid metal stream in continuous vacuum distillation equipment typically feeds a complex path with narrow passages. The route and these narrow passages are more prone to being clogged by the intermetallic compounds emerging from the solution and seeking attachment to a fixed anchor point.
The inventors have determined that in particular chromium (Cr), manganese (Mn), vanadium (V), titanium (Ti), tungsten (W), copper (Cu), nickel (Ni), iron (Fe), zinc ( Zn) and aluminum (AI) are metals whose presence in the solder feed to the vacuum distillation step can lead to the disruptive intermetallic compounds during the vacuum distillation of the solder. Of these potentially interfering metals, it is Cu, Ni, Fe, Zn and AI for which it is typically more important to control them. The reason for this is that it is more advantageous to recover tin and / or lead from raw materials containing Cu, Ni, Fe, Zn and AI. Iron and / or aluminum can also be introduced into the process upstream of the tin and / or lead recovery step for process reasons. Thus, the presence of Cu, Ni, Fe, Zn, and AI in the crude solder intermediate from which it is desired to recover the tin and / or lead is more likely and results from choices in the upstream process steps and from the choice of raw materials for the upstream process steps, usually of a pyrometallurgical nature.
The inventors have determined that the identified
Problems can be greatly reduced and sifts prevented by controlling the concentration of these within certain levels
BE2017 / 5681 metals in the solder feed to the distillation step in which the solder is separated into more concentrated streams by evaporation of at least a portion of the lead.
The inventors have further determined that these potentially harmful metals, and especially copper, must not be completely removed from the solder in order to make the solder suitable for vacuum distillation. For example, the inventors have determined that the identified probes can be reduced to a practically and economically acceptable level when small amounts of copper remain in the solder feed to the distillation step. This finding offers the advantage that brazing currents that act as a by-product of the recovery of copper from primary and / or secondary raw materials, more specifically from secondary raw materials, more particularly from raw materials containing end-of-life materials, can be processed .
The metal mixture of the present invention comprises at least 0.0001 wt% sulfur (S). We have determined that it is not necessary to bring the sulfur levels down to very low levels, such as below the detection limit of 1 ppm by weight, in order to obtain the result sought by the sulfur content control. The presence of sulfur in the metal mixture, on the other hand, provides a technical advantage.
We have found that sulfur binds fairly easily to copper to form a copper sulfide (such as CuS), and that the copper sulfide can be easily separated by gravity from the liquid metal mixture containing the two major components in the process, ie tin and lead . The presence of sulfur can therefore contribute to the removal of Cu in any process step where Cu is to be scratched into a supernatant
BE2017 / 5681 separated. Applicants do prefer to include S as a process chemical in the process of the present invention. We have determined that the addition of sulfur-containing chemical compounds, such as pyrite (FeS), may actually be suitable for this purpose of reducing the copper content of the metal mixture of the present invention, but we prefer the use of elemental sulfur by using it avoids the introduction of one or more additional chemical elements. Therefore, sulfur in any form, and more specifically elemental sulfur, is a very suitable chemical process substance for the inventors for the removal of some of the unwanted metals, more specifically copper.
Thus, the presence of sulfur in the metal mixture of the present invention is a strong indicator that the metal mixture of the present invention was produced as a by-product from a copper production process. As a result, the starting material for the process of the present invention may likely contain measurable amounts of copper as an impurity, such as the content specified. The copper content of such output currents can be reduced by a variety of possible process steps, of which the binding of Cu by S is only one. Any S treatment for the removal of Cu most likely leaves measurable traces of S in the metal mixture. Thus, the presence of S in the metal mixture of the present invention provides a strong relationship to the metal mixture produced as a by-product of copper production, preferably in a step comprising treatment with sulfur or a suitable S-containing compound.
We have further determined that the presence of sulfur in the metal mixture of the present invention does not
BE2017 / 5681 problem, provided that some buyer is also present, as specified. The S present may contribute in subsequent cleaning steps by removing Cu from the streams of less precious metals on their route to ultimately achieve an industrially acceptable quality. Thus, the S in the metal mixture of the present invention is preferably present and provides advantages downstream of the process.
CN 1 899 738 A discloses a method of soldering between the inner sleeve and the outer sleeve of a pile material for coating. The brazing solder as specified in the document is prepared deliberately and is said to contain primarily Pb and Sn, some Sb, and otherwise no more than 0.5% by weight of impurities. The impurities are further specified as, inter alia, a maximum of 0.08 wt% Cu and a maximum of 0.02 wt% S. CN 1 899 738 A does not disclose a brazing material comprising at least 1 ppm Cu by weight and at least 0.0001% by weight, including 1 ppm by weight, of sulfur. The hard solder of CN 1 899 738 A is not intended for the recovery of high purity Pb and / or Sn from it.
We have determined that the composition of the present invention can be easily subjected to a distillation step to remove most of the lead in the composition by evaporation. We have determined that such distillation can produce a lead-rich overhead product stream that can be easily further purified by conventional means to obtain a lead product corresponding to many of the commercial standards, while producing a bottom stream rich in tin but also the major portion of the antimony (Sb) contained in the product of the pretreatment, along with a minimum presence of lead (Pb). We
BE2017 / 5681 have determined that the presence of antimony (Sb) is not necessarily detrimental to this separation, provided that the antimony content remains within reasonable limits and the prescribed Pb content remains in the Sn-rich bottoms of the distillation operation . Applicants believe that the Pb remaining in the Sn product of the distillation serves as an additional solvent for the antimony, to a significant level that can be tolerated, as described later in this document. Applicants further believe that, by not evaporating out all the Pb that comes with the solder feed, most of the antimony entering with the solder feed for the vacuum distillation also remains in the bottom product, thus producing a Pb distillate with a low antimony content thus, it is easier to purify to obtain a high purity lead product, also called "soft lead", with the properties desirable for specific composition sensitive lead applications.
We have further found that the problem of the formation of intermetallic compounds during the vacuum distillation of the metal mixture of the present invention is further alleviated by leaving at least the prescribed concentration of lead in the bottoms of the distillation step. We believe that this amount of lead has a beneficial impact to better keep potentially harmful metals in solution and reduce their tendency to form potentially interfering intermetallic compounds.
We have further determined that the presence of a minimal amount of lead in the bottoms of the vacuum distillation conducted as part of the method of the present invention makes it easier to remove silver or other precious metals in the bottoms by means of a
BE2017 / 5681 crystallizer using a technique as described in CN102534249, which describes a 4-step crystallizer operation for purifying a raw tin stream by removing silver.
We have determined that the method of the present invention can process a feed rich in lead, contains significant amounts of tin (Sn), and contains antimony (Sb) as well as copper (Cu) within specified limits, and on the other hand, can produce a distillate can be used for further purification in a high purity commercial grade lead product, and alternatively a liquid molten metal mixture which can be used for further upgrade in commercially important quantities of several of the metals present, in particular the tin, the antimony and the residual lead, but possibly with other metal values such as precious metals, mainly silver (Ag).
Applicants point out that the upstream process which produces the raw solder that can be used as a feed stream for the process of the present invention is typically conducted at a high temperature, typically much higher than the specified 500 ° C, previously in the range of 7001000 ° C. Applicants further point out that the final step of the process according to the present invention, i.e. the vacuum distillation step, should generally be performed at an even higher temperature. As explained above in the background section, the typical temperatures for removing lead from tin by vacuum distillation are at least 900 ° C, often even 1100 ° C.
Applicants therefore argue that step b) of the method according to the present invention is counter-intuitive. Applicants argue that anyone normally skilled in the art would prefer to keep the solder at the high temperature at which it was produced, possibly even further heating it before
BE2017 / 5681 subject to a vacuum distillation step for separating lead from tin. Applicants have found, however, that the cooling step b) as part of the process of the present invention, without the intervention of other chemicals, a significant portion of the components in the solder that are undesirable in the feed for the vacuum distillation step, the context of the present invention, may transition to a supernatant scratch phase, thereby making this scratch phase available to be separated from the liquid metal phase. Applicants have found that this cooling step contributes significantly to the creation of a separate scratch phase rich in the unwanted components, leaving behind a liquid metal phase containing less of these unwanted components and thus more suitable for a vacuum distillation step in which fewer operational problems occurrence caused by the possible formation of intermetallic compounds during the distillation step. Applicants have determined that the cooling step is specifically capable of reducing the copper, nickel, iron and / or zinc content in the remaining liquid soldering phase.
Applicants argue that as part of the process of the present invention, step c) further reduces the concentration of the unwanted metals in the liquid metal phase on its way to vacuum distillation. However, this step consumes chemicals as specified. Applicants argue that the cooling step b) provides the additional advantage that the subsequent chemical treatment step c) requires fewer chemicals. The chemical (s) specified for step c) eventually act as a base, and this base ends in the scratch that is removed, at least in step d). The scratch contains valuable metals, and it is economically interesting to reuse the scratch phases that separate from the liquid metal phase as part of the process according to
BE2017 / 5681 the present invention, for the recovery of the valuable metals. However, many of the known recovery methods for these metals from such scratch currents are of a pyrometallurgical nature. They operate at very high temperatures, so high that most of the structural steel of the equipment that comes in contact with the high temperature process streams is usually protected by heat resistant material. However, the chemicals used in step c), and ending in the scratch phase separated in step d), are aggressive to the most commonly used heat-resistant materials used in the typical pyrometallurgical non-ferrous metal recovery process steps. Applicants argue that the cooling step b) therefore not only contributes to keeping the chemical (s) content introduced in step c) low, but also contributes to the level of acceptability for reuse of the scratch separated in step d) in order to obtain metal values therefrom to be recovered by a pyrometallurgical method.
We have determined that in the cooling step b) mainly iron and nickel can chemically bond with tin and that these compounds can float, provided the underlying liquid stream contains sufficient lead, as specified elsewhere in this document, and thus has a sufficiently high density .
We have determined that the chemical introduced in step c) can bind to some of the unwanted metals, mainly zinc, in a form that also readily floats under the same condition as stated above in step b).
Brief description of the drawings
The Figure shows a flow chart of an embodiment of the method according to an embodiment of the
BE2017 / 5681 present invention.
Detailed description
The present invention is described below with reference to specific embodiments and with reference to certain drawings, but the invention is not limited thereto, only by the claims. All drawings described are purely schematic and not limiting. In the drawings, the size of some elements may be exaggerated and not drawn to scale for illustrative purposes. The dimensions and relative dimensions do not necessarily correspond to actual reductions for the practice of the invention.
Furthermore, the terms first, second, third and the like are used in the description and in the claims to distinguish between similar elements and not necessarily for describing a sequential or chronological order. The terms are interchangeable under appropriate circumstances and the embodiments of the invention may operate in sequences other than described or illustrated herein.
In addition, the terms top, bottom, over, under and the like in the description and the claims are used for descriptive purposes and not necessarily for description of relative positions. The terms thus used are interchangeable under appropriate conditions and the embodiments of the invention described herein may operate in orientations other than those described or illustrated herein.
As used herein and in the claims, the terms encompassing and including are inclusive or open-ended and do not exclude additional unlisted elements, composition components, or process steps. In addition, the terms comprising and
BE2017 / 5681 including the more restrictive terms consisting mainly of ”and consisting of.
Unless otherwise noted, all values provided herein include up to the specified end points, and the values of the constituents or components of the compositions are expressed in weight percent or wt% of each ingredient in the composition.
Additionally, any compound used herein can be interchangeably described with respect to its chemical formula, chemical name, abbreviation, etc.
In the context of the present invention, "smelter", "melting", "melting" or similar derivations of "melting" mean a method that involves much more than just changing the aggregation state of a substance from solid to liquid. In a pyrometallurgical smelter step, several chemical processes also occur that convert certain chemical compounds into other chemical compounds. Important of these conversions can be oxidations, with or without the formation of an oxide, or reductions, in which the oxidation state of some atoms change.
In the context of the present invention, "scratch" or "scratches" means an often pasty substance which forms as a result of an operational step and which separates from another liquid phase, usually under the influence of gravity, and usually floats to the surface. The scratch or scratches can therefore usually be mechanically scraped off or removed from the underlying liquid.
In the context of the present invention, by "the solder", or also "the solder", is meant a metal composition which is rich in tin and / or lead, but which may also contain other metals. Solder typically has a relatively low melting temperature, making the composition suitable for heating to a relatively low temperature
BE2017 / 5681 limited temperature, when cooling can form a metal connection between two other metal parts, the so-called "soldering",
In this document and unless otherwise noted, amounts of metals and oxides are expressed according to typical Pyrometallurgy practice. The presence of each metal is typically expressed in its total presence, regardless of whether the metal is present in its elemental form (oxidation state = 0) or in any chemically bonded form, usually in an oxidized form (oxidation state> 0). For those metals that can be relatively easily reduced to their elemental shapes, and which can exist as molten metal in the pyrometallurgical process, it is quite common to express their presence in terms of their elemental metal shape, even when the composition of a slag or scratch, where the majority of such metals may actually be present in an oxidized and / or chemically bonded form. It is therefore that the composition of the metal mixture of the present invention specifies the content of Fe, Zn, Pb, Cu, Sb, Bi as elemental metals. Less precious metals are more difficult to reduce under non-ferrous pyrometallurgical conditions and are most common in oxidized form. These metals are then usually expressed in terms of their most common oxide form. Therefore, in slag or scratch compositions, the content of Si, Ca, Al, Na is usually expressed as SiO ₂ , CaO, Al ₂ O ₃ , Na ₂ O, respectively.
In one embodiment, the metal mixture of the present invention comprises up to 0.10 wt% of the total chromium (Cr), manganese (Mn), vanadium (V), titanium (Ti) and tungsten (W) together, preferably up to 0.010 wt%, more preferably up to 0.005 wt%, even more preferably up to 0.0010 wt%, preferably up to 0.0005 wt%, more preferred
BE2017 / 5681 up to 0.0001 wt% chromium (Cr), manganese (Mn), vanadium (V), titanium (Ti) and tungsten (W) together. We have determined that the risk of the formation of potentially interfering intermetallic compounds is reduced by controlling the presence of these compounds below lower levels.
In one embodiment, the metal mixture according to the present invention comprises at least 0.0001% by weight of the total chromium (Cr), manganese (Mn), vanadium (V), titanium (Ti) and tungsten (W) together, preferably at least 0.0005 wt%, more preferably at least 0.0010 wt%, even more preferably at least 0.0020 wt%, preferably at least 0.0030 wt%, more preferably at least 0.0050 wt%, even more preferably at least 0.010 wt% of the total chromium (Cr), manganese (Mn), vanadium (V), titanium (Ti) and tungsten (W) together. We have determined that it is not essential to obtain a satisfactory distillation operation to remove these compounds to very low levels, if below their detection limit of about 1 ppm by weight. On the other hand, we have also found that removal of these compounds to very low levels requires significant additional effort, process steps, chemicals and attention, and that the additional benefit in the distillation operation does not justify the extent of these extras. We have determined that it is therefore advantageous to control the presence of these compounds within two measurable limits, as stated above.
In one embodiment, the liquid molten metal feed composition pretreated in the method of the present invention comprises at least 0.5%, more preferably at least 0.75%, even more preferably at least 1.0%, preferably at least 1.5%, more preferably at least 2.0%, even more preferably at least 2.5%, with even greater
BE2017 / 5681 preferred at least 3.0% of the total chromium (Cr), manganese (Mn), vanadium (V), titanium (Ti), tungsten (W), copper (Cu), nickel (Ni), iron (Fe), aluminum (AI) and / or zinc (Zn) together. We have determined that a raw solder containing these compounds at the specified levels can easily be pretreated with success by the method of the present invention so that the downstream vacuum distillation can operate without affecting the formation of intermetallic compounds over a longer period of time. This offers the advantage that the method of the present invention can process a raw solder which can be obtained by the pyrometallurgical processing of a wide variety of raw materials and using a wide variety of metal-containing auxiliary materials in those upstream process steps. Particularly advantageous is the ability to process a solder obtained as a by-product of a copper melt and refining operations for which secondary raw materials have been supplied. These secondary raw materials can come from a wide range of sources and thus contain a wide range of other compounds, more specifically metals other than lead and / or tin. A further advantage is that also the copper content of the raw solder intended for vacuum distillation does not have to be reduced to very low levels, which reduces the quality pressure on the performance of the upstream process steps, giving these process steps more freedom and thus higher efficiency and / or capacity within the same equipment limitations. Applicants have determined that the pretreatment steps of the method of the present invention can easily deal with the significant levels of the unwanted components as specified. In addition, the specified levels of these components do not necessarily lead to a higher consumption of chemical process substances and to larger ones
BE2017 / 5681
Problems in any pyrometallurgical step for the recovery of the metal values from the scratch that was removed in step d), because most of the unwanted components can already be removed or even removed by the specified physical means, such as step b).
In one embodiment, the liquid molten metal feed composition that was pretreated in the method of the present invention comprises up to 10.0%, preferably up to 8.0%, more preferably up to 6.0%, even more preferably up to 5.0%, preferably up to 4.0%, more preferably up to 3.0%, even more preferably up to 2.0%, of the total of chromium (Cr), manganese (Mn), vanadium ( V), titanium (Ti), tungsten (W), copper (Cu), nickel (Ni), iron (Fe), aluminum (AI) and / or zinc (Zn) together. We have found that respecting the upper limit as prescribed results in the pretreatment steps of the method of the present invention being more effective in obtaining the desired results in a more efficient manner because the requirements in terms of energy and chemicals remain limited, practical and economical. A further advantage of a limited presence of the specified components is that the amount of scratch remains limited. Any scratch removed inevitably also contains some valuable metals. Thus, the scratch also represents a loss of valuable metals from the main process streams which were intended to recover the desired metals, mainly tin and / or lead in the present context, but possibly also other metals such as antimony and precious metals. Even if the scratch is recycled to a process point upstream of the process of the present invention, the amount of desired metals recycled with the scratch represents an inefficiency of the
BE2017 / 5681 processes. Reducing this process loss and / or inefficiency due to the limitations described above is therefore a general process advantage. A further advantage of this property is also that less lead will circulate in the general process in which the metal feed composition is produced and pretreated. The processing of lead-containing metal streams at high temperatures presents its own problems with regard to industrial hygiene. Thus, the specified characteristic also contributes to a lower and / or more controlled industrial hygiene problem associated with the recovery of tin and / or lead as a by-product from the production of copper or other non-ferrous metals.
In one embodiment, the liquid molten metal feed composition that is pretreated in the method of the present invention is available at a temperature of at least 510 ° C, preferably at least 520 ° C, more preferably at least 550 ° C, with even more preferably at least 575 ° C, preferably at least 600 ° C, more preferably at least 650 ° C, even more preferably at least 700 ° C, preferably at least 750 ° C, with greater preferably at least 775 ° C, even more preferably at least 800 ° C, even more preferably at least 830 ° C. We have found that a higher feed temperature contributes to a more liquid feed stream in the upstream process where the feed stream is prepared. We have also determined that, at a higher temperature, the intermetallic compounds that form between copper and tin, and thus will need to be removed to some extent as part of the present invention, that these intermetallic compounds are susceptible to absorb less tin take for the same amount of copper. Thus, a higher temperature contributes to a more efficient removal of copper contamination because the removed
BE2017 / 5681 intermetallic compounds then drag less of the valuable tin away from the molten metal compound, which continues its path towards the main products. We have further found that a higher raw solder feed temperature allows the pretreatment steps to be performed more effectively and efficiently. For example, we have found that a higher supply temperature provides more room for cooling, and a wider range of cooling is more effective in the removal of the target metal compounds, ie those capable of forming intermetallic compounds downstream in the distillation, more specifically when removing copper.
In one embodiment, the liquid molten metal feed composition that is pretreated in the method of the present invention is available at a temperature of up to 1000 ° C, preferably up to 980 ° C, more preferably up to 960 ° C. We have found that limiting the supply temperature below the specified limits provides the advantage that the energy requirements of upstream process steps remain practical, sufficiently efficient and economical. Higher temperatures, above the specified limits, do not appear to provide sufficient additional benefits to justify the additional energy input in whatever form this energy input occurs, including chemical energy.
In one embodiment, the liquid molten metal feed composition that is pretreated in the method of the present invention is cooled to a temperature of up to 820 ° C, preferably up to 800 ° C, more preferably up to 750 ° C, with an even greater preferably maximum 700 ° C, even more preferably maximum 650 ° C, preferably maximum 600 ° C, even more preferably maximum 550 ° C, preferably maximum
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525 ° C, more preferably up to 500 ° C, even more preferably up to 450 ° C, preferably up to 400 ° C, more preferably up to 370 ° C, even more preferably up to 360 ° C, at preferably up to 350 ° C, more preferably up to 345 ° C, even more preferably up to 330 ° C, preferably up to 320 ° C, more preferably up to 310 ° C to produce a bath containing a first supernatant scratch which floats by gravity on top of a first liquid molten metal phase. We found that the solder cooling removes at least a portion of several of the less desirable metals, more specifically copper but also nickel, iron, zinc and aluminum, and of chromium, manganese, vanadium, titanium and tungsten, as one of it would be present. We further found that when the cooling range is wider and / or lower in temperature, more of these metals come out of solution and end up in the supernatant scratch. The wider the cooling path is made, the more susceptible the cooling step becomes to be split into several consecutive cow steps, preferably combined with intermediate scratch removal. This offers the advantage that, overall, less scratch will have to be removed to remove the same amount of unwanted metals, and the total amount of scratch will contain less of the target metals of the general process, which are primarily lead and / or tin, but also includes the various noble metals which may be present in the solder and under specific conditions also the antimony (Sb) which may be present. We also found that the colder the raw solder, the higher its density, which is beneficial for gravity separation from the scratch, as the scratch floats more easily on top of the denser liquid metal phase.
In one embodiment, the feed composition of
BE2017 / 5681 liquid molten metal that has been pretreated in a method of the present invention cooled to a temperature of at least 230 ° C, preferably at least 232 ° C, more preferably at least 240 ° C, even more preferred at least 250 ° C, more preferably at least 270 ° C, even more preferably at least 280 ° C, preferably at least 290 ° C, more preferably at least 300 ° C, even more preferred at least 310 ° C, preferably at least 320 ° C, more preferably at least 325 ° C, even more preferably at least 328 ° C. We have determined, thanks to this lower limit of the cooling step, that less tin is consumed when bonded to the same amount of copper to be removed. Without wishing to be bound by this theory, applicants believe that this is due to the fact that the formation of Cu ₆ Sn _{5 is} more preferred and the formation of Cu ₃ Sn 5 is less preferred at the lower temperatures. The lower limit of the cooling step therefore reduces the amount of valuable tin to be removed along with the same amount of copper in the scratch. Even if the scratch is optionally recycled upstream in the process, this property shows an improvement in efficiency because less tin has to be recycled in that process for the same amount of copper removed by the cooling step of the process of the present invention.
In the cooling step, we have further determined that it is preferable to respect the minimum temperature as specified, as this ensures that the metal remains fluid and that its viscosity remains sufficiently low to allow the solids formed by cooling and / or by allowing the chemical reactions triggered by the addition of chemical compounds to rise to the surface and to be removed from the underlying liquid metal phase by skimming.
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The main objective of adding the prescribed compound in step c) of the method of the present invention is to remove most of any zinc that may be present in the raw solder.
In one embodiment, the bottoms obtained by the process of the present invention, in the distillation step of lead removal, comprise more than 0.60 wt% lead, preferably at least 0.65 wt% lead, with a more preferably at least 0.70 wt% lead, even more preferably at least 0.75 wt% lead, preferably at least 0.80 wt% lead, preferably at least 1.0 wt%, more preferably at least 1.5 wt%, even more preferably at least 2.0 wt%, preferably at least 3.0 wt%, more preferably at least 4.0 wt% , even more preferably at least 5.0 wt%, and even more preferably at least 6.0 wt% lead. We believe that higher levels of Pb remaining in the Sn product of the distillation can serve as an additional solvent, for example, for the amount of antimony that may be present in the feed to the distillation step. This solubility effect can be advantageous for the separation in the distillation step. The main purpose of the vacuum distillation step as part of the process of the present invention is to evaporate lead (Pb) and produce a lead-containing overhead distillate suitable for further cleaning by conventional means to produce a product of more high-purity lead, the so-called “soft lead”. We believe that leaving an amount of lead in the bottoms of the distillation step helps achieve this objective by providing a liquid phase that remains attractive to many of the metals other than lead, thereby reducing the tendency of these metals to become volatile as well as their tendency to escape from the liquid phase
BE2017 / 5681 and ending in the top distillate of the distillation step. We believe this benefit is enhanced by maintaining a higher concentration of lead in the bottoms from the distillation step. We believe this advantage is especially important for any antimony present in the feed to the distillation step of the method of the present invention.
We have further found that the problems of formation of intermetallic compounds during the vacuum distillation of the metal mixture according to the present invention are further alleviated by keeping a greater presence of lead in the bottoms of the distillation step. We believe that the increased amount of lead has a beneficial impact in better dissolution of potentially harmful metals and in reducing their tendency to form the potentially interfering intermetallic compounds during the upstream distillation step. Without wishing to be bound by theory, we believe this effect may be based on dilution, but we suspect that there may be additional factors that play a role in reducing the risk of intermetallic compound formation under the conditions that occur in the vacuum distillation step.
In one embodiment, the bottoms obtained in the distillation step by the removal of lead comprise up to 10.0 wt% lead, preferably up to 9.0 wt% lead, more preferably up to 8.0 wt%, with an even more preferred maximum 7.0 wt%, preferably maximum 6.5 wt%, more preferably maximum 6.0 wt%, even more preferably maximum 5.0 wt% and with a further more preferably maximum 4.0 wt% lead. We have found that not exceeding this prescribed lead content in the bottoms from the distillation step downstream provides the advantage of further separating the various
BE2017 / 5681 facilitates metals present in the bottom product in order to obtain a tin main product that meets most international industry standards for high quality tin content. We have further found that keeping the lead content between the prescribed limits provides a practical and economical balance between the benefits obtained by the presence of lead in the liquid through the distillation step on the one hand, and the downstream task of upgrading the bottoms of the distillation on the other hand in at least one high-quality tin main product in combination with one or more by-products containing the other metals present in the distillation bottoms product, by-products of which are suitable for further processing and easy upgrading into high-quality by-product streams. We have further determined that a limited presence of lead in the bottoms product is advantageous if precious metals are also present and these precious metals should be recovered downstream of the vacuum distillation from its bottoms stream. This recovery can be carried out, for example, in a crystallizer, such as described in CN102534249, for removing silver from a crude tin product containing a high content of silver, and thus capable of separating a crystalline Sn-rich phase from a liquid effluent in which the precious metals are combined with most of the lead present, but inevitably leaving some of the most valuable tin behind. We have found that limiting the amount of lead remaining in the bottom of the vacuum distillation reduces the amount of effluent in such a crystallizer and results in an effluent more concentrated in the desired precious metals, and thus more interesting for further processing for recovery of the precious metals. Another advantage is that less of the valuable tin is lost in the drain and thus remains available in the flow leading to the tin
BE2017 / 5681 main product.
In one embodiment, the metal mixture of the present invention comprises at least 15 wt% tin, preferably at least 20%, more preferably at least 22%, even more preferably at least 24 wt%, preferably at least 26 wt%, more preferably at least 28 wt%, even more preferably at least 30 wt% tin. We have found that a larger amount of tin in the solder lowers the melting point of the mixture, with the advantage that a wider temperature range is available for the pre-treatment of the raw solder to prepare the solder for trouble-free vacuum distillation. As stated elsewhere in this document, this provides the advantage that more of the intended metals can come out of the solution and end up in the scratch, which can be easily removed from the molten metal phase. We have also found that the high-purity tin metal that can be recovered from the metal mixture of the present invention is more preferred than the high-purity lead metal that can be recovered from the same metal mixture. The tin main product derived from the metal mixture is therefore of higher economic value than any lead-containing main product. Thus, a higher tin content increases the economic interest in the metal mixture of the present invention as a raw material for the recovery of high purity tin metal.
In one embodiment, the metal mixture of the present invention comprises 45 wt% lead, preferably at least 50 wt%, more preferably at least 55 wt%, even more preferably at least 60 wt% lead. We found that a higher lead content in the liquid metal mixture improves the separation of the scratch from the liquid metal phase. With the higher concentration of lead in the liquid metal, the scratch goes, which
BE2017 / 5681 typically has a lower density, floats faster and more easily on the liquid metal phase and then forms a more clearly separated scratch phase which can be removed with less entrapment of solder, and thus also with the valuable tin and lead. Under these conditions, the scratch therefore also contains less of the valuable metal tin and lead. More of the tin and lead thus remains available in the pre-treated solder for upgrade to high-quality main products. When the scratch is recycled to a process step upstream from the pretreatment step of the method of the present invention, the better separation reduces the amount of tin and lead recycled upstream and the amount of which must be processed to end up in the raw solder feed to the method of the present invention. We have also found that a higher lead content, and thus generally a lower tin content of the solder, has the advantage that the solubility of copper in the solder is reduced, leading to a lower copper content in the final tin main product derived from the bottoms of the vacuum distillation, and an increase in the economic value of this tin main product and / or a reduction in the burden of removing the residual traces of copper in a downstream process step, plus the rework associated with the recovery of scratch in such a downstream process step is created.
In one embodiment, the metal mixture according to the present invention comprises a maximum of 80% by weight of lead, preferably a maximum of 75%, more preferably a maximum of 70%, even more preferably a maximum of 65%, preferably a maximum of 60% by weight of lead. We have determined that an excessive amount of lead in the liquid metal mixture does not have the advantages associated with a larger amount of lead in the mixture according to the present invention
BE2017 / 5681 further improves. We have further determined that an excessive amount of lead dilutes the more valuable tin in the metal mixture, thereby diminishing interest in this metal mixture as a feedstock for recovery of high purity tin.
In one embodiment, the metal mixture of the present invention comprises at least 91 wt% tin and lead together, preferably at least 92%, more preferably at least 93%, even more preferably at least 94%, with another more preferably at least 95%, preferably at least 96%, more preferably at least 96.5%, even more preferably at least 97%, even more preferably at least 97.5%, preferably at least at least 98%, more preferably at least 98.5%, even more preferably at least 98.7% by weight of tin and lead together. The metal mixture of the present invention is interesting as a feed stream for the recovery of high purity tin and lead, with the vacuum distillation step of the process of the present invention as an important process element. Hence, a higher tin and lead content together increases the amount of main products that can be recovered from the metal mixture, and thus reduces the amount of by-product streams which usually have a lower value and which may arise from the further purification of the distillation products in main product streams. This reduces the workload required for the removal of these non-main products to a level imposed by the main product specifications, which should preferably meet the highest possible international trade standards in practice. This workload includes the consumption of chemicals and energy, as well as manpower and equipment investment costs. The higher content of tin and lead combined thus increases the economic interest in the metal mixture according to the present invention as a raw material for the recovery of
BE2017 / 5681 high purity tin metal, as well as lead metal in economically acceptable forms.
In one embodiment, the metal mixture of the present invention comprises at least 2 ppm copper by weight, more preferably at least 3 ppm, even more preferably at least 4 ppm, even more preferably at least 5 ppm copper on by weight, preferably at least 6 ppm, more preferably at least 7 ppm, even more preferably at least 8 ppm, even more preferably at least 9 ppm copper by weight, preferably at least 10 ppm, more preferably at least 12 ppm, even more preferably at least 14 ppm, even more preferably at least 15 ppm copper by weight, preferably at least 16 ppm, more preferably at least 18 ppm and even more preferably at least 20 ppm copper by weight. We have determined that the specified amounts of copper may remain in the metal mixture of the present invention without compromising the suitability of the metal mixture as a feed stream for the vacuum distillation step, and thus also without significant reduction or destruction of the effect obtained by the the present invention, ie an increase in the risk that a vacuum distillation step performed on the metal mixture would no longer be able to operate in a continuous mode for a longer period without encountering the problems of intermetallic compounds containing copper and that the distillation can affect operations. We have found that the identified problems that can be reduced to a practical and economically acceptable level when the small amounts of copper, as specified, remain in the metal mixture of the present invention when used as
BE2017 / 5681 soldering supply to the distillation step.
The higher allowable copper content in the metal mixture, as specified above, also has the advantage that the upstream processes from which the feed stream of the method of the present invention is derived enjoy greater operating freedom. These processes may even be involved in the pyrometallurgical recovery of copper metal. The processes which produce a raw solder as a by-product of the feed stream for the process of the present invention can also recover main metals other than tin and / or lead from a much wider range of possible raw materials, primary as well as secondary, and including metal-containing materials to the end of their lifespan.
In one embodiment, the metal blend of the present invention comprises up to 4500 ppm copper by weight, preferably up to 4000 ppm, more preferably up to 3500 ppm, even more preferably up to 3000 ppm, even more preferably up to 2500 ppm , preferably up to 2000 ppm, more preferably up to 1500 ppm, even more preferably up to 1250 ppm, even more preferably up to 1000 ppm, preferably up to 800 ppm, more preferably up to 600 ppm, with an additional more preferably up to 400 ppm, even more preferably up to 200 ppm, preferably up to 150 ppm, more preferably up to 100 ppm, even more preferably up to 75 ppm copper. We found that the lower the concentration of copper in the metal mixture of the present invention, the lower the risk of forming intermetallic compounds when the metal mixture is subjected to vacuum distillation to remove at least a portion of the lead in the mixture by evaporation.
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We have further determined that the lower the copper content in the metal mixture according to the present invention, the lower the concentration of copper in the product streams from the downstream vacuum distillation. This reduces the burden of further removing copper from these streams on their way to main product formation, more specifically in terms of chemical consumption and in terms of amounts of by-products formed, which are preferred upstream of the process of the present invention, and thus also in terms of reducing the potentially deleterious effects of these chemicals in this recycling operation, such as by attacking the refractory in a pyrometallurgical step.
In one embodiment, the metal mixture according to the present invention comprises at most 0.10 wt% zinc (Zn), preferably at most 0.010%, more preferably at most 0.0050%, even more preferably at most 0.0010%, at preferably up to 0.0005%, more preferably up to 0.0001% wt. zinc. We have determined that vacuum distillation performed on the metal mixture according to the present invention can be particularly sensitive to the presence of zinc. Zinc may primarily form intermetallic compounds, and thus may contribute to the problem addressed by the present invention. Zinc is also a rather volatile metal, and any zinc present can also become at least part of the vapor phase in the distillation equipment. The heating in the distillation equipment is often electrically conducted by passing an electric current through heating electrodes in the distillation equipment. We found that controlling the presence of zinc within the prescribed limits reduces the risk of electric arcs occurring between two points of these heating electrodes that are closed
BE2017 / 5681 may be located together and between which there is a voltage difference. Such electrical arcs represent a short circuit in the electrical circuit of the heating system, and often cause immediate equipment failure. Absence or malfunction of fuses can cause damage to the transformer and the DC-AC converter in the electrical system. The arcs damage and can destroy the electrodes and can also burn through the oven wall, more particularly when pulled between an electrode and the oven wall.
In one embodiment, the metal mixture of the present invention comprises at least 0.0001 wt% zinc (Zn), preferably at least 0.0005%, more preferably at least 0.0010%, even more preferably at least 0.0050%, preferably at least 0.010%, more preferably at least 0.050% by weight of zinc. We have determined that it is not necessary to remove zinc to extremely low levels in order to sufficiently alleviate the problems that zinc may cause during the vacuum distillation of the metal mixture of the present invention. We have determined that small amounts of zinc, as specified, can thus be left in the metal mixture as a feed for vacuum distillation. We found that the specified limits allow the desired low levels of zinc in the main end products to be easily achieved.
In one embodiment, the metal mixture of the present invention comprises up to 0.10 wt. nickel (Ni), preferably up to 0.050%, more preferably up to 0.010%, preferably up to 0.0050%, more preferably up to 0.0010 wt% nickel (Ni). Nickel is a metal present in many raw materials available for the recovery of non-BE2017 / 5681 ferrous metals, especially in secondary raw materials, and especially in end-of-life materials. It is therefore important for the recovery of non-ferrous metals that the process can tolerate the presence of nickel. Furthermore, the pyrometallurgical processes for the recovery of non-ferrous metals often consume significant amounts of iron as a chemical process substance. It is advantageous to be able to use secondary iron-containing materials for this purpose. In addition to large amounts of iron, these materials can also contain small amounts of nickel. It is advantageous to also be able to handle these types of chemical process substances. However, Nikkei is also a metal that can form intermetallic compounds during vacuum distillation. We have determined that control within the specified limits of the amount of nickel present in the metal mixture of the present invention can sufficiently reduce the risk of formation of nickel-containing intermetallic compounds during vacuum distillation of the metal mixture. We have further determined that it is preferable to lower the nickel content in the solder feed to the vacuum distillation step rather than removing larger amounts of nickel downstream from the process. Such downstream nickel removal is usually performed in conjunction with the removal of arsenic (As) and / or antimony (Sb) and pose a risk of generating the highly toxic gases arsine (AsH3) and / or stibine (SbH3). Thus, the removal of nickel to within the specified limits also reduces the downstream risk of toxic gas formation, and is thus also a measure of safety and industrial hygiene.
In one embodiment, the metal mixture of the present invention comprises at least 0.0005 wt% nickel (Ni), preferably at least 0.0010%, more preferably at least
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0.0050%, preferably at least 0.010%, more preferably at least 0.050% by weight nickel (Ni). We have determined that it is not essential to reduce nickel to very low levels, if below the detection limit of 1 ppm by weight. We have determined that control within the specified limits of the content of nickel present in the metal mixture of the present invention can sufficiently reduce the risk of the formation of nickel-containing intermetallic compounds during vacuum distillation of the metal mixture, as well as an increased risk with respect to safety and industrial hygiene downstream associated with possible generation of arsine and / or stibine gas can be avoided, while avoiding unnecessary operations for cleaning up the metal mixture in its preparation as a vacuum distillation feed.
In one embodiment, the metal mixture of the present invention comprises up to 10% by weight of antimony (Sb), preferably up to 8%, more preferably up to 6%, preferably less than 6%, even more preferably up to 5.5 %, preferably at most 5.0%, more preferably at most 4.5%, even more preferably at most 4.0%, even more preferably at most 3.5%, preferably at most 3.0%, more preferably up to 2.5%, even more preferably up to 2.0%, preferably up to 1.5%, more preferably up to 1.1% by weight of antimony (Sb). We have determined that antimony may be allowed into the metal mixture of the present invention, within specific limits, without creating problems when the metal mixture is used as a vacuum distillation feed. We have determined that it is important to keep the amount of antimony below the specified upper limit because antimony can also at least partially evaporate below the
BE2017 / 5681 distillation conditions. If the antimony content is higher, the amount of antimony exiting the distillation step along with the high lead containing overhead distillate can become significant. In order to obtain the main lead product that meets the desired industry standards, this amount of antimony must be removed from this lead stream in the conventional cleaning steps downstream of the distillation step. An amount of antimony above the specified limit increases the workload of these downstream cleaning steps and increases the amount of by-product streams containing the antimony. Since these by-product streams can also contain significant amounts of lead, this lead in the by-products does not end in the main lead product and at least reduces the effectiveness of the general operation. Excessive amounts of antimony also tend to raise the melting temperature of the tin-enriched liquid in the distillation equipment and downstream. This would necessitate operation at even higher temperatures, which increases equipment wear.
In one embodiment, the metal mixture of the present invention comprises more than 0.42% by weight of antimony (Sb), preferably at least 0.43%, more preferably at least 0.45%, even more preferably at least 0.47%, preferably at least 0.50%, more preferably at least 0.55%, even more preferably at least 0.60%, even more preferably at least 0.65%, at preferably at least 0.75%, more preferably at least 1.0%, even more preferably at least 1.5%, preferably at least 2.0%, more preferably at least 2.5 wt .% antimony (Sb). We have determined that the metal mixture of the present invention may contain measurable, and even significant, amounts of antimony within the specified
BE2017 / 5681 without this presence of antimony significantly interfering with the downstream vacuum distillation step to which the metal mixture can be subjected. We have found that this provides additional freedom of operation for the upstream processes from which the feed stream for the method of the present invention is derived. Thanks to this admission of an amount of antimony in the raw solder they produce as an intermediate stream and as feed for the process of the present invention, these upstream processes can accept an amount of raw material in which antimony is present. Antimony can be present in a variety of primary and secondary raw materials for non-ferrous metals, as well as in many end-of-life materials. For example, antimony may be present in lead that has been used for plumbing since Roman times. These materials can now become available as breakdown materials, often in combination with copper for tubing and other purposes, and with tin and lead for the solder joints. Allowing an amount of antimony in the metal mixture of the present invention, and thus also in the raw solder that is the feed stream to the method of the present invention, leads the upstream processes to accept such mixed materials at the end of their life . We found that significant concentrations of antimony are allowed in the mixed metal of the present invention without creating significant difficulties for the process of the present invention, as well as for the downstream processes that further upgrade the top and bottom flows generated by the vacuum distillation .
In one embodiment, the metal mixture of the present invention comprises up to 0.10 wt% iron (Fe), preferably
BE2017 / 5681 up to 0.070%, more preferably up to 0.050%, even more preferably up to 0.010%, preferably up to 0.0050%, more preferably up to 0.003% by weight, even more preferably up to 0, 0030 wt% iron. Iron is a metal that is present in many raw materials available for the recovery of non-ferrous metals, especially in secondary raw materials, and especially end-of-life materials. Furthermore, the pyrometallurgical processes for recovering non-ferrous metals often consume significant amounts of iron as a process chemical. Iron is a metal that can form intermetallic compounds during vacuum distillation. We have determined that control within the specified limits of the amount of iron present in the metal mixture of the present invention can sufficiently reduce the risk of the formation of iron-containing intermetallic compounds during vacuum distillation of the metal mixture.
In one embodiment, the metal mixture of the present invention comprises at least 0.0001 wt% iron (Fe), preferably at least 0.0002%, more preferably at least 0.0003%, even more preferably at least 0.0005%, preferably at least 0.0010%, more preferably at least 0.0015%, even more preferably at least 0.0020 wt% iron. We have determined that it is not essential to remove iron to very low levels, such as below the detection limit of 1 ppm by weight. We have determined that a control within the specified limits of the amount of iron present in the metal mixture of the present invention can sufficiently reduce the risk of the formation of iron-containing intermetallic compounds during vacuum distillation of the metal mixture, while avoiding unnecessary cleaning operations from
BE2017 / 5681 the metal mixture in its preparation as a feed for vacuum distillation.
In one embodiment, the metal mixture of the present invention comprises up to 0.10 wt% aluminum (Al), preferably up to 0.050%, more preferably up to 0.010%, even more preferably up to 0.0050%, with another more preferably up to 0.0010%, preferably up to 0.0005%, more preferably up to 0.0001% by weight aluminum. Aluminum is a metal present in many raw materials available for the recovery of non-ferrous metals, especially in secondary raw materials, and especially in end-of-life materials such as used beverage cans. Furthermore, the pyrometallurgical processes for recovering non-ferrous metals can use aluminum as a process chemical, such as aluminum granulate, for the removal of copper from solder type liquid metal streams. Aluminum is a metal that can form intermetallic compounds during vacuum distillation. We have determined that control within the specified limits of the amount of aluminum present in the metal mixture of the present invention can sufficiently reduce the risk of aluminum-containing intermetallic compounds forming during vacuum distillation of the metal mixture.
In one embodiment, the metal mixture of the present invention comprises at least 0.0001 wt% aluminum (Al), preferably at least 0.0002%, more preferably at least 0.0003%, even more preferably at least 0.0005%, preferably at least 0.0010%, more preferably at least 0.0015%, even more preferably at least 0.0020% by weight aluminum. We found that it is not essential to remove aluminum to very low levels, such as below the
BE2017 / 5681 detection limit of 1 ppm based on weight. We have determined that control within the specified limits of the amount of aluminum present in the metal mixture of the present invention can sufficiently reduce the risk of aluminum-containing intermetallic compounds during vacuum distillation of the metal mixture, while avoiding unnecessary operations to clean up the metal mixture. metal mixture in its preparation as a feed for vacuum distillation.
In one embodiment, the metal mixture according to the present invention comprises a maximum of 0.10% by weight of sulfur (S), preferably a maximum of 0.070%, more preferably a maximum of 0.050%, even more preferably a maximum of 0.010%, preferably a maximum of 0, 0050%, more preferably up to 0.0030 wt% sulfur. We have determined that the presence of sulfur in the metal mixture of the present invention can cause odor problems and industrial hygiene problems, even if the sulfur-containing metal and / or the slag and / or the scratch has cooled and cured. These problems can arise during operations and during storage, but can be even more important during maintenance interventions. We therefore prefer to lower the sulfur levels in the metal mixture of the present invention to within the specified upper limits.
In one embodiment, the metal mixture of the present invention comprises 0.0001 wt% sulfur (S), preferably at least 0.0002 wt%, more preferably at least 0.0003%, even more preferably at least 0.0005%, preferably at least 0.0010%, more preferably at least 0.0015%, even more preferably at least 0.0020 wt% sulfur. We have determined that it is not necessary to reduce sulfur levels to very low levels, such as the detection limit of 1 ppm based on
BE2017 / 5681 weight, in order to obtain the result aimed at controlling the sulfur content. The presence of sulfur in the metal mixture, on the other hand, provides a technical advantage.
We have found that sulfur binds fairly easily to copper to form a copper sulfide (such as CuS), and that the copper sulfide readily separates by gravity from the liquid metal mixture containing the two main components in the process, i.e., tin and lead. Therefore, the presence of S in the process of the present invention is preferred, as is the presence of sulfur in the metal mixture according to the present invention. We have found that retaining a small amount of sulfur in the metal mixture according to the present invention contributes to further reducing the small amounts of copper remaining in the metal mixture by binding the Cu to sulfide and transferring it to further scratches that may are formed in further downstream cleaning steps in the general process. The S is preferably introduced into the process or product in a form that can and can be easily converted to a portion of copper sulfide. We have determined that sulfur-containing chemical compounds, such as pyrite (FeS), can also be used, the more we prefer the use of elemental sulfur because its use prevents the introduction of one or more additional chemical elements. Therefore, sulfur, and more specifically elemental sulfur, is a very suitable chemical process substance for the inventors in the removal of some of the unwanted metals, especially copper.
In one embodiment, the metal mixture according to the present invention comprises at least 10 ppm silver (Ag) by weight, preferably at least 50 ppm, more preferably at least 100 ppm, even more preferably at least 125 ppm and
BE2017 / 5681 even more preferably at least 150 ppm silver by weight. We have determined that silver may be allowed in the process streams of the present invention in amounts - which are significant for such a precious metal - without interfering with the vacuum distillation step, as it has been found that silver does not readily form intermetallic compounds during the vacuum distillation step and the operations do not affects. This tolerance to silver causes the upstream processes, which produce the raw solder that is the appropriate feed stream for the process of the present invention, and which is the origin of the metal mixture of the present invention, to accept raw materials containing silver. In addition, the silver in the raw materials can be present in very low amounts, but is already somewhat concentrated in the raw solder produced upstream, and even more concentrated in the mixed metal of the present invention, and then can be even more concentrated in the bottoms from the vacuum distillation step of the method of the present invention. Thus, the sequence of pyrometallurgical process steps counts as sequence of concentration steps by the precious and precious metal that is silver, and thus represents an interesting pretreatment for a silver metal recovery process. The recovery of silver from the bottom stream from the distillation of the metal mixture of the present invention should therefore be easier compared to an attempt to recover from any of the intermediate streams upstream, and probably also for the majority of the raw materials containing silver and which are used as starting materials for the upstream processes that generate the raw solder that forms the feed for the process of the present invention.
In one embodiment, the metal mixture of
BE2017 / 5681 the present invention up to 2000 ppm silver (Ag) by weight, preferably up to 1800 ppm, more preferably up to 1700 ppm, even more preferably up to 1600 ppm, even more preferably up to 1500 ppm, preferably up to 1400 ppm, more preferably up to 1350 ppm, preferably up to 1300 ppm, more preferably up to 1200 ppm, even more preferably up to 1100 ppm, preferably up to 1000 ppm, more preferably up to 900 ppm silver by weight. We have found that silver above the specified concentration becomes less beneficial and may even become detrimental. At the higher silver contents in the feed to the vacuum distillation, some of the silver can actually evaporate and be part of the vapor phase in the distillation step. As a result, some of the extremely valuable silver cannot find its way to the bottoms of the distillation step, from which it can be recovered in a practical by-product in a suitable by-product through the downstream processes intended to produce the high purity tin main product stream.
In one embodiment, the metal mixture of the present invention comprises at least 10 ppm bismuth (Bi) by weight, preferably at least 50 ppm, more preferably at least 100 ppm, even more preferably at least 150 ppm, and still more preferred at least 200 ppm bismuth by weight, and optionally up to 2000 ppm bismuth by weight, preferably up to 1800 ppm, more preferably up to 1500 ppm, even more preferably up to 1300 ppm, with still more preferably up to 1100 ppm, preferably up to 1000 ppm, more preferably up to 950 ppm bismuth based on weight. We found that bismuth can be relatively volatile under the conditions of the vacuum distillation step. A part of
BE2017 / 5681 the bismuth can therefore find its way to the upstream of the distillation step, from which it may then have to be removed in order to obtain a lead main product that meets the desired product specifications. This downstream removal of contaminants consumes chemicals and creates a by-product stream that also contains some valuable lead. Even when recycled with successes, these by-product streams represent a product inefficiency that is better reduced.
In one embodiment, the metal mixture of the present invention comprises at least 10 ppm arsenic (As) by weight, preferably at least 100 ppm, more preferably at least 200 ppm, even more preferably at least 300 ppm, and even more preferred at least 350 ppm arsenic by weight. This feature brings the advantage that raw materials containing some arsenic can be accepted by the upstream process steps from which the solder feed for the process of the present invention is derived. We have determined that the general process, including the process of the present invention, but also including all downstream steps for further cleaning or upstream steps to which downstream by-product streams can be recycled, can process the amounts of arsenic as specified. In addition, the inventors have determined that some commercially important alloys readily accept As to certain levels without any significant problems, and that select types of such alloys even welcome the presence of As. The metal mixture as well as the method of the present invention is therefore prepared to accept the presence of As in its process streams, although within the specified limits.
In one embodiment, the metal mixture of
BE2017 / 5681 the present invention maximum 2000 ppm arsenic based on weight, preferably maximum 1900 ppm, more preferably maximum 1800 ppm, even more preferred maximum 1700 ppm, even more preferred maximum 1600 ppm, preferably maximum 1500 ppm, more preferably up to 1400 ppm arsenic by weight. We prefer to keep the amount of arsenic within limits. This reduces the workload for removing arsenic downstream of each of the product streams from the vacuum distillation step. These removal steps use chemicals and generate by-product streams that inevitably also contain certain amounts of valuable metals such as lead and / or tin. Even when recycled with successes, these by-product streams exhibit general process inefficiency and are advantageous to reduce. Recycling can also cause problems with the chemicals caused by these by-product streams, such as a corrosive effect of sodium hydroxide on refractories used in the equipment and in contact with the hot liquid streams.
In one embodiment, the metal mixture according to the present invention comprises at least 10 ppm indium (In) by weight, preferably at least 50 ppm, more preferably at least 100 ppm indium by weight. We have determined that the presence of indium can be acceptable within realistic limits. This allows the upstream process steps to accept raw materials containing indium which may be unacceptable in other processes for the recovery of non-ferrous metals from raw materials containing a variety of different metals.
In one embodiment, the metal mixture according to the present invention comprises a maximum of 1000 ppm indium based on
BE2017 / 5681 weight, preferably up to 800 ppm, more preferably up to 700 ppm, even more preferably up to 600 ppm, even more preferably up to 500 ppm, preferably up to 400 ppm, more preferably up to 300 ppm indium by weight. We have found that indium in significant amounts, in the presence of arsenic, can form particularly stable intermetallic compounds. These compounds are characterized by a relatively low density and thus easily float on the liquid metal phase, more specifically when the latter contains lead. When this occurs in a vacuum distillation step, the intermetallic compounds can actually interfere with the evaporation of lead from the liquid, thus significantly reducing the performance of the vacuum distillation. We therefore prefer to limit the concentration of indium in the metal mixture of the present invention to within the specified limits.
In one embodiment, the method of the present invention includes the step of removing the first supernatant scratch from the batch before step c). We prefer to remove the scratch from each pretreatment step before starting the next pretreatment step. We have found that this has the advantage of reducing the overall amount of scratch compared to the alternative where the scratch is combined from several steps and removed together at the end of the pretreatment steps. A scratch also contains some tin and / or lead, so these amounts of valuable metals are disadvantageously removed from the metal stream fed to the distillation step. These amounts of valuable metals also increase the workload of rework the scratch to recover the metal values therein, including the entrained tin and / or lead, as well as the
BE2017 / 5681 other metals that were removed from the liquid metal stream by the pretreatment.
In an embodiment of the method of the present invention, the method of obtaining the feed composition comprises a metal melting step in which at least one of the removed scratches is recycled to the melting step, preferably all supernatant scratches formed and separated are recycled to the melting step. We have determined that an upstream smelting step, such as a copper smelter, is not only a suitable nonferrous metal recovery step for generating a crude solder flux as a by-product that can be subjected to the process of the present invention, and for generating, by the pretreatment step of the metal mixture of the present invention, but it is also an extremely suitable point for recycling at least one of the scratches produced in the pretreatment steps of the method of the present invention. We choose to recycle the first supernatant scratch generated by the cooling in step b), as well as the second supernatant scratch removed in step d), following the chemical reaction that occurs in step c).
Thus, in step c), an alkali metal and / or an alkaline earth metal may be administered, such as the addition of sodium metal. In this case, we choose to also add some water to react with the sodium to form its hydroxide and / or oxide, compounds that bind more easily to zinc. However, we prefer to administer the alkali metal and / or alkaline earth metal in a chemically bonded form, more preferably as a solid, because we have found that a bonded form performs better, and because the solid generally has a lower density than the pure
BE2017 / 5681 metal form so that all excess floats on the liquid metal and can be removed together with the scratch. The bonded form can be, for example, an oxide, but is preferably a hydroxide. We have determined that Calcium Hydroxide (Ca (OH) ₂ ) and Potassium Hydroxide (KOH) can be used, but we prefer the use of sodium hydroxide (NaOH), preferably in its solid form, as it is more efficient by weight for binding to a certain amount of zinc, and also the most readily available form of suitable compounds. We have further determined that the addition of the prescribed compound contributes to better phase separation between the solid supernatant scratch and the underlying liquid metal phase. Better phase separation contributes to a brighter scratch containing less of the main metals lead and tin, and thus to a more effective and useful recovery of these valuable metals, as well as higher process efficiency.
In an embodiment of the method of the present invention, in step c), the alkali metal and / or the alkaline earth metal is added in a chemically bonded form, preferably as a solid. We have determined that the addition of a pure metal form may be appropriate, but we prefer the use of a chemically bonded form. Thus, the chemically bonded form provides the alkali metal and / or the alkaline earth metal in a more permissible form to be chemically reacted with the target metals before being removed in the pretreatment steps. We have found that the reaction products of the chemically bonded form with the target metals, such as, for example, Na ₂ ZnO ₂ , are more easily separated by gravity from the molten liquid stream, and thus can be more easily removed as a purer stream containing less valuable metals.
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In an embodiment of the method of the present invention, in step c), the alkali metal and / or the alkaline earth metal is added as an oxide or a hydroxide, preferably as a hydroxide. We have determined that the process can easily handle the oxygen and hydrogen that accompany the metal in its chemically bonded form. We have found that this form also avoids the introduction of chemical elements, which would make the process more difficult.
In an embodiment of the method of the present invention, sodium hydroxide is added in step c). We have determined that sodium hydroxide is best suited for this pretreatment step. We also found that sodium hydroxide is more readily available and in more attractive delivery conditions than other chemically bonded forms of alkali and / or alkaline earth metals.
In an embodiment of the method of the present invention, the feed composition contains at least 0.0010 wt% zinc (Zn) and, together with an oxygen source, provides an ignition source above and after the alkali metal addition and / or the alkaline earth metal. We have found that when zinc is present in at least the prescribed amounts, the alkali metal and / or the alkaline earth metal added in step c) reacts with the zinc in a reaction that generates hydrogen gas as a by-product. This is especially true when sodium hydroxide is added, which generates Na ₂ ZnO ₂ and hydrogen gas. The Na ₂ ZnO ₂ ends in the scratch, but the hydrogen gas is released from the bath. Hydrogen gas has very wide explosion limits in mixture with air (its lower flammability limit (LFL) in air is only 4 vol.%), And the atmosphere above the bath is usually not chemically inert but mainly air and hot. The
BE2017 / 5681 generation of hydrogen gas in step c) therefore represents an explosion hazard. The air above the bath provides an oxygen source. We also prefer to provide an ignition source above the bath during and after the addition of the alkali metal and / or the alkaline earth metal, so that the hydrogen generated is easily burned before the composition of the mixture of air and hydrogen above the bath enters the explosion limits.
In an embodiment of the method according to the present invention, the second liquid molten metal phase comprises at least 100 ppm copper by weight and as part of the method, sulfur is added to the bath formed in step c). We found that sulfur readily reacts with the copper present and can further and significantly reduce the copper content of the metal mixture. The addition of sulfur has been found to generate a scratch containing the copper, at least in part in the form of a sulfide of copper (eg CuS), and we have found that this scratch has a low density so that it floats easily on the molten liquid solder based on lead and tin together.
Not all copper could easily bind to the sulfur and small amounts of copper downstream of the sulfur treatment are permissible. We prefer to maintain a small presence of sulfur because we have found this to be advantageous in further cleaning up the streams produced from the metal mixture according to the present invention by the evaporation of lead from the mixture. By retaining a small amount of sulfur after the sulfur treatment and scratch separation, the small amounts of Cu and S are given more time to find each other and are converted into copper sulfide, which can then be separated from the metal product streams as part of further downstream steps from the vacuum distillation.
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In the embodiment in which sulfur is added to the bath formed in step c), the bath temperature is up to 400 ° C, preferably up to 375 ° C, and more preferably up to 350 ° C. We have found that this has the advantage of being more effective because less sulfur runs the risk of being burnt out before it is able to reach the liquid metal bath and react with copper.
In an embodiment of the method of the present invention, the feed composition comprises copper and the method comprises the step of adding sulfur to the product of step d) in at least the stoichiometric amount required to react with the amount of copper (Cu ) present, preferably at least 2% over stoichiometry, more preferably at least 5% over stoichiometry, even more preferably at least 110% from stoichiometry. We have found that the sulfur reacts easily and preferably with the copper present in the raw solder, forming a scratch containing the copper in the sulfide form, such as CuS. We found that the specified excess sulfur over stoichiometry contributes to a successful reduction of the copper content to the desired levels. We have determined, by adding the amounts of sulfur within the limits specified in this document, that copper contents can be obtained as low as 150 ppm by weight or even lower.
In one embodiment, the sulfur is added at a level of up to 200% of the stoichiometric amount required to react with the amount of copper (Cu) present, preferably up to 150%, more preferably up to 125% of stoichiometry, with even more preferably up to 120%, even more preferably up to 115% of stoichiometry. We
BE2017 / 5681 have determined that the amounts of sulfur are sufficient to obtain an acceptable removal of copper present in the raw solder and to obtain the target concentrations of copper in the metal mixture of the present invention, as specified elsewhere in this document, and to obtain a composition that can be used as a feed for a vacuum distillation step as part of the method of the present invention. We have determined that no excessive sulfur excess is required for successful reduction of the copper to the desired levels. In addition, the sulfur-containing scratch can be recycled to an upstream pyrometallurgical process step, where the sulfur can form volatile sulfur oxides. Thus, additional sulfur above the specified levels in the process of the present invention increases the scavenging burden on the waste gases from the upstream process steps to which the sulfur-containing scratch that is formed here is recycled. Therefore, we prefer to keep the amount of sulfur added within the specified limits.
In the embodiment of the method of the present invention wherein an ignition source is provided above the bath, the ignition source is provided by adding elemental sulfur to the atmosphere above the bath. We have found that elemental sulfur ignites easily under the conditions above the bath during the pretreatment step, and can ensure that all hydrogen present is burned even when the hydrogen concentration is below the lower flammability limit. We have further determined that the added sulfur can participate in and contribute to the reduction of the copper content through chemical bonding of the copper and transfer of the copper into a scratch. Preferably all sulfur used for
BE2017 / 5681 removal of the copper as elemental sulfur added to the atmosphere above the bath. We prefer to add elemental sulfur as a granulate rather than as a powder. We prefer a dedusted granulate because fine sulfur dust ignites too quickly and corresponds to a less efficient use of the sulfur, and thus may require a higher sulfur consumption to obtain the same effect.
This form of elemental sulfur is readily available from many sources under attractive supply conditions. This form of elemental sulfur can also be easily distributed over a large part of the surface of the bath and is thus very effective in burning away hydrogen over this large part of the bath surface, and thus also effective in reducing the risk of explosion. caused by the generation of hydrogen. The granulate form offers the added benefit of generating less dust, thus avoiding potential industrial hygiene problems due to sulfur dust in the working environment and atmosphere, in addition to a more effective use of the sulfur as less sulfur can be blown away during the treatment and the bath over which it is to be spread is thus not reached.
In the embodiment of the method of the present invention wherein elemental sulfur is added and a third scratch is formed containing copper, the method further comprises removing the third scratch from the bath. We choose to remove that copper-containing scratch separately from the first and the second scratch, with the advantage of limiting the total amount of scratch that is removed. We also choose to recycle this third scratch to an upstream melting step, if any, more specifically to an upstream copper melting step, as the ideal location for recovery of the copper and of the tin and / or lead that is almost
BE2017 / 5681 is inevitably co-removed as part of the third scratch from the molten metal bath in the method of the present invention.
In the embodiment of the method of the present invention in which a third scratch is removed, an amount of alkali metal and / or alkaline earth metal is added to the bath after the removal of the third scratch. Similar to the reasons explained above with respect to the material added in step c) as a process chemical, we prefer the use of a chemically bonded form and / or a solid form. More preferably, we use an oxide or a hydroxide, more preferably a hydroxide, and even more preferably sodium hydroxide. We found that this additional NaOH readily reacts with the remaining sulfur to form a sodium sulfite (typically Na ₂ SO ₂ ) and hydrogen gas as a by-product. The sodium sulfite again forms a scratch phase which is preferably also removed from the bath. The hydrogen is released from the bath as hydrogen gas in the atmosphere above the bath. Similar reactions occur with the alternatives of the NaOH in this step.
In the embodiment of the method of the present invention, after removing a third scratch and adding an amount of alkali metal and / or alkaline earth metal to the bath, an ignition source is provided above the bath. We prefer that the ignition source be provided by adding elemental sulfur to the atmosphere above the bath. We have found that elemental sulfur ignites easily under the existing conditions above the bath during the pretreatment step and can ensure that all hydrogen present is burned even when the hydrogen concentration is below the lower flammability limit. We choose to add the elemental sulfur as one
BE2017 / 5681 granules, rather than as a powder, with the same additional comments as made above with regard to a preferred low dust content. This form of elemental sulfur is readily available from many sources under attractive supply conditions. This form of elemental sulfur can also be easily distributed over a large part of the surface of the bath and is thus very effective in burning away hydrogen over this large part of the bath surface, and thus also effective in reducing the risk of explosion. caused by the generation of hydrogen. The granulate form provides the added benefit of generating less dust, thereby avoiding potential industrial hygiene problems due to sulfur dust in the working environment and atmosphere, in addition to more effective use of the sulfur as less sulfur can be blown away during the treatment and the bath over which it is to be spread is thus not reached.
In an embodiment of the method of the present invention, a silicon source is added to the bath. We prefer the use of a source of silicon dioxide, more preferably sand. We choose to add this silicon source to the bath before removing at least one of the scratches, preferably before removing the third scratch, if any, but alternatively before removing the first scratch or the second scratch, more preferably remove any of the scratches. We have found that this silicon source, in particular when the added compound contains silicon dioxide, such as sand, offers the advantage of "scratching" of the scratch, ie making the scratch less liquid, increasing its viscosity, making it behave more like a solid. This change in the consistency of the scratch facilitates collection of the scratch and removal of the
BE2017 / 5681 scratch off the bath by skimming. The scratch thus treated has also become "drier", i.e. it can be collected and removed with a lower entrainment of valuable metals. This improves both the effectiveness and the efficiency of the general method of producing main metals. We have determined that silicon dioxide is very suitable for use for stiffening a scratch. Sand is a convenient and easily and economically available silicon dioxide source that is sufficiently pure to obtain the result without adversely affecting the process in any way. The silicon dioxide in the scratch can be easily recycled with the scratch to an upstream melting step, where the silicon dioxide typically ends up in the slag by-product of the melter, and in which it can provide further advantages. Preferably, the sand is distributed over a large area of the bath surface, so that its stiffening effect achieves a large amount of the scratch that is currently floating on top of the liquid metal in the bath.
We prefer using an amount of sand not more than 5 wt% relative to the amount of chemical compound added in step c), in preferred embodiments, relative to the amount of NaOH added in step c). More preferably we use a maximum of 4% by weight, even more preferably a maximum of 3%, preferably a maximum of 2%, more preferably a minimum of 1%, a still more preferably a maximum of 0.5%, with a further more preferably up to 0.1 wt% sand, relative to the total amount of chemical compound added in step c). We prefer to add the sand in several successive sub-steps.
The distillation step as part of the process of the present invention can be performed under very low pressure, such as no more than 50 Pa absolute, possibly no more than 10-15 Pa, and
BE2017 / 5681 often only 0.1-5 Pa, in combination with relatively high temperatures of at least 800 ° C, preferably at least 900 ° C. The vacuum distillation of the solder-type metal mixtures can be carried out batchwise, and such charge-vacuum distillation techniques are disclosed in CN101696475, CN104141152, CN101570826, and in Yang et al, "Recycling of metals from waste Sn-based alloys by vacuum separation", Transactions of Nonferrous Metals Society of China, 25 (2015), 1315-1324, Elsevier Science Press. Vacuum distillation of metals can also be performed in continuous mode, and such continuous distillation techniques are disclosed in CN102352443, CN104651626 and CN104593614.
In an embodiment of the method of the present invention, the distillation step is performed in continuous operation mode.
In an embodiment of the method according to the present invention, the distillation step is carried out at a pressure of up to 15 Pa absolute, preferably up to 10 Pa, more preferably up to 5 Pa, even more preferably up to 1 Pa, with even greater preferably maximum 0.7 Pa absolute. We have found that a lower pressure is advantageous because it facilitates the separation of the more volatile metals from the less volatile metals. The other advantage is that the separation can be performed at a lower temperature than when using a higher operating pressure. This offers the advantage that the operation is also more energetically efficient.
In an embodiment of the method according to the present invention, the distillation step is performed at a temperature of at least 800 ° C, preferably at least 850 ° C, more preferably at least 900 ° C, even more preferably at least 930 ° C. We have found a higher temperature
BE2017 / 5681 promotes the separation of the metals in a vapor and residual liquid phase, for example because the higher temperature increases the volatility of the more volatile metal or metals. The higher temperature may also increase the difference in volatility between the metal or metals to be evaporated and the metal or metals to be kept in the liquid phase. We have further determined that a higher temperature also reduces the risk of intermetallic compounds forming and / or adhering to the walls of the equipment and thus potentially interfering with distillation operations.
In one embodiment, the method of the present invention is monitored and / or controlled at least partially electronically, and preferably by a computer program. We have found that the control of steps of the method by a computer program entails a much better process management, with more predictable results that come closer to the objectives. The control program can, for example on the basis of temperature measurements, where necessary also measurements of pressure and / or liquid levels, in combination with results of chemical analyzes of samples taken from process flows and / or analysis results obtained on-line, control the equipment with regard to the addition or discharge of electrical energy, supply of heat or coolant, a flow rate and / or a pressure control. We have found that this is especially the case with the steps performed in continuous mode, but it can also be advantageous with these steps performed in batch. Also preferably, the measurement results obtained during and after implementation of this method are useful for monitoring and / or controlling other methods mentioned in this invention, or methods used in previous or next steps in the entire production process of which the method according to the present invention
BE2017 / 5681. Preferably, the entire process is monitored electronically and / or by one or more computer programs and preferably controlled as much as possible.
Applicants also prefer that the computer controller provide that data and instructions from one computer or computer program be transferred to at least one other computer or computer program or module of the same computer program, for the purpose of monitoring and / or controlling other methods, although then not described herein.
Example
The following example shows the effect of cleaning a raw solder when this solder is to be subjected to a vacuum distillation step. The enclosed Figure shows a flow chart of the process steps and their sequence used in this example. The compositions reported in this example are expressed in units of weight, resulting from analyzes of samples taken daily and averaging these results over a 3 month period.
For the analysis of a metal flow, a sample of liquid metal is taken, poured into a mold and cooled to solidify. One surface of the solid sample is prepared by passing the sample through a Herzog HAF / 2 grinder once or preferably several times until a clean and flat surface is obtained. The clean and flat sample surface is then analyzed using a spark-optical emission spectroscopy (OES) device Spectrolab M from Spectra Analytical Instruments (US), also available from Ametek (DE), where the parameters, crystals, detectors and tube can be easily selected and adjusted to provide the most appropriate operation
BE2017 / 5681 for the desired accuracy and / or detection limit. The analysis provides results for a variety of metals in the steel, including copper, bismuth, lead, tin, antimony, silver, iron, zinc, indium, arsenic, nickel, cadmium and even the element sulfur, for most of these metals up to a detection limit of about 1 ppm by weight.
For the analysis of a scratch, the inventors prefer to use a correctly calibrated X-ray fluorescence (XRF) technique, preferably using the PANalytical Axios XRF spectrometer from PANalytical B.V. (NL). This technique is also preferred over the above-mentioned OES for analyzing samples of metals containing significant amounts of contaminants, such as stream 4 and streams upstream thereof, in the flow chart in the accompanying Figure. This technique also allows for easy selection and adjustment of the details in order to optimize the results in terms of accuracy and / or limit of detection that best meets the objective of the analysis.
The raw solder stock is from the refining of copper, lead and tin-containing materials (Stream 1) in a copper smelter that produces a "black copper" intermediate containing about 85 wt% Cu. This black copper was then subjected in a copper refinery to a series of pyrometallurgical refining steps which produce, on the one hand, a higher purity copper main product, and, on the other hand, a number of slag by-products. Melter and copper refining are presented as step 100 in the Figure. As part of the refining operations, the raw solder is recovered as stream 2 from some of these refinery slag. The raw solder had the composition as shown in Table 1. Purification of this raw solder is performed to remove a significant amount of the metal impurities still present,
BE2017 / 5681, the presence of which could otherwise adversely affect the downstream vacuum distillation step. The target impurities for the cleaning steps are mainly Cu (1.6176%), Fe (44ppm), Ni (11ppm) and Zn (573ppm), and the objective of the raw solder cleaning is that the solder can be easily processed further by by means of vacuum distillation.
Table 1: Raw solder from the refinery
Element Wt% Bi 0.0267 Cu 1.6176 Fe 0.0044 Ni 0.0011 Pb 73.5960 Sb 0.6927 Sn 24.0041 Zn 0.0573 Total 99.9999
The raw solder was available from the upstream refining operations at a temperature of about 835 ° C. In a first part 200 of the cleaning operation sequence, the solder was cooled to 334 ° C in two steps. In the first step, the raw solder was cooled to about 500 ° C and a first scratch was removed from the surface of the molten liquid. In the second step, the raw solder was further cooled to 334 ° C and a second scratch was removed from the surface of the molten liquid. The cooling step 200 formed a total scratch containing the majority of the copper present in the raw solder, which was removed as a by-product (stream 9). The concentrations of the target metals in the residual solder intermediate (stream 3) are shown in Table 2. The copper content in the solder was reduced from 1.6176% to 0.6000% by this sequence of cow steps and scratch removals.
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The Fe and Zn concentrations in the solder also decreased significantly. All scratches formed during the cooling operation were removed and recycled upstream in the process to the smelter step (shown as stream 9) so that its valuable metal content could be valorized as much as possible.
Table 2: The solder after the cooling step
Wt% Solder Bi 0.0288 Cu 0.6000 Fe 0.0010 Ni 0.0028 Pb 71.0685 Sb 0.8151 Sn 27.2817 Zn 0.0033 Ag 0.0783 Au 0.0020 Ash 0.0902 CD 0.0031 In 0.0225 S 0.0027 To 0.0020 Total 100.0020
In a second cleaning step 300, solid sodium hydroxide (stream 13) was added to the solder intermediate of Table 2. In this treatment step, zinc was bound by the sodium hydroxide, presumably to form Na ₂ ZnO _2, to form a separate phase which separated as a solid supernatant from the solder and was removed as stream 10. As a result, the zinc content in the soldering current 4 is further reduced. The amount of sodium hydroxide was adjusted so that the Zn concentration in the solder dropped to 16 ppm by weight (Table 3). The scratch formed in this step was also recycled (stream 10) to the upstream smelter step as
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Table 3: Solder part of box 100 in the Figure after the first NaOH treatment.
Element Wt% Bi 0.0309 Cu 0.3550 Fe 0.0006 Ni 0.0017 Pb 72.9626 Sb 0.8635 Sn 25.6014 Zn 0.0016 Ag 0.0546 Ash 0.0998 CD 0.0034 In 0.0208 S 0.0031 To 0.0012 Total 100,0001
In the further cleaning step 400, downstream of step
300 using sodium hydroxide, an amount of elemental sulfur (stream 14) representing about 130% of stoichiometry relative to the amount of copper present in the metal phase was added to further reduce the copper content of the solder.
Granulated sulfur obtained from the company Zaklady Chemiczne Siarkopol in Tarnobrzeg (PL) was used as the elemental sulfur. The sulfur 14 reacted primarily with copper to form copper sulfides which transitioned to a new supernatant scratch phase. The scratch was removed as stream 11. After the addition of sulfur in step 400, a further amount of sodium hydroxide (stream 15) was added in step 500 to chemically bind any remaining traces of sulfur to form another scratch. After allowing the reaction for some time, a handful of granulated sulfur was scattered / spread on the bath surface. The sulfur ignited and burned away all the hydrogen
BE2017 / 5681 from the liquid could have emerged as a by-product of the reaction. A small amount of white sand was then scattered / spread over the bath to dry / stiffen the scratch. The total scratch formed in step 500 was then removed from the liquid metal bath as stream 12. The purified solder thus obtained (stream 6, the composition of which is shown in Table 4) contained only 38 ppm Cu and was further processed with vacuum distillation in step 600. The sulfur-containing scratch 12 was incorporated into the upstream refining process 100 so that its valuable metal content could be valorized.
Table 4: Cleaned solder for vacuum distillation
Element Wt% Bi 0.0326 Cu 0.0038 Fe 0.0004 Ni 0.0009 Pb 73.1206 Sb 0.8012 Sn 25.8694 Zn 0.0013 Ag 0.0537 Ash 0.0871 CD 0.0020 In 0.0202 S 0.0053 To 0.0010 Total 99.9995
The cleaned solder 6 was then further processed by vacuum distillation at an average temperature of 982 ° C and an average absolute pressure of 0.012 mbar (1.2 Pa). The vacuum distillation step produced two product streams that could be further purified into high-quality main products according to industry standards. On the one hand, as a top stream 7, we obtained one
BE2017 / 5681 product stream mainly containing lead and on the other hand, as bottom product 8, we obtained a product stream mainly containing tin. The compositions of these two distillation product streams 7 and 8 are shown in Table 5.
Table 5: Product flows of vacuum distillation
Wt% Lead current(Top) Tin current(Bottom) Bi 0.0518 0.0014 Cu 0.0000 0.0273 Fe 0.0006 0.0000 Ni 0.0022 Pb 99.5375 1.0055 Sb 0.2233 2.3664 Sn 0.1006 96.2129 Zn 0.0000 0.0001 Ag 0.0031 0.2153 Ash 0.0746 0.1193 CD 0.0012 0.0000 In 0.0057 0.0481 S 0.0016 To 0.0000 Total 100.0000 99.9989
The vacuum distillation was performed in continuous mode and for a period of about three (3) years without any blockage or clogging of the distillation equipment by the formation of intermetallic compounds. Both product streams from the vacuum distillation step remained usable for further refining for the entire time period, in steps 700 and 800, respectively, to form main products in accordance with established international industry standards.
Having fully described this invention, anyone skilled in the art will recognize that the invention can be practiced in a wide variety of parameters within what is claimed, without departing from the scope of the invention,
BE2017 / 5681 as defined by the claims.
BE2017 / 5681

权利要求:
Claims (35)
[1]
CONCLUSIONS
A metal mixture containing lead (Pb) and tin (Sn), comprising the mixture, by weight,
- at least 10% tin,
- at least 45% lead,
- at least 90% tin and lead together,
- more lead than tin,
- at least 1 ppm and at most 5000 ppm copper,
- at least 0.42% antimony (Sb), and
- at least 0.0001% sulfur (S), and
- up to 0,1% of the total of chromium (Cr), manganese (Mn), vanadium (V), titanium (Ti) and tungsten (W),
- maximum 0.1% aluminum (Al),
- up to 0.1% nickel (Ni),
- maximum 0,1% iron (Fe), and
- maximum 0.1% zinc (Zn).
[2]
The metal mixture according to claim 1 comprising at least 15% by weight of tin.
[3]
The metal mixture according to claim 1 or 2 comprising at least 50% by weight of lead.
[4]
The metal mixture further comprises one of the preceding claims, comprising at least 91% by weight of tin and lead together.
[5]
The metal mixture according to any one of the preceding conclusions, comprising at least 2 ppm wt. buyer.
[6]
6. The metal mixture according to any one of the preceding conclusions, comprising at least 2 ppm wt. sulfur.
[7]
The metal mixture according to any one of the preceding conclusions, comprising a maximum of 4500 ppm wt. buyer.
[8]
The metal mixture according to any one of the preceding conclusions, comprising a maximum of 0.10 wt.% Zinc (Zn).
BE2017 / 5681
[9]
The metal mixture according to any one of the preceding claims, comprising a maximum of 0.10% by weight of nickel (Ni).
[10]
The metal mixture according to any one of the preceding claims comprising a maximum of 10% by weight of antimony (Sb).
[11]
The metal mixture according to any one of the preceding claims comprising a maximum of 0.10% by weight of iron (Fe).
[12]
The metal mixture according to any one of the preceding claims, comprising a maximum of 0.10% by weight of aluminum (Al).
[13]
The metal mixture according to any one of the preceding claims, comprising a maximum of 0.10% by weight of sulfur (S).
[14]
The metal mixture according to any one of the preceding claims comprising at least 10 ppm wt. silver (Ag).
[15]
The metal mixture according to any one of the preceding claims comprising at least 10 ppm wt. bismuth (Bi).
[16]
The metal mixture according to any one of the preceding claims comprising at least 10 ppm wt. arsenic (As).
[17]
The metal mixture according to any one of the preceding claims comprising at least 10 ppm wt. indium (In).
[18]
A method of separating by distilling the metal mixture according to any one of the preceding claims comprising the step of pretreating a liquid molten metal feed composition,
a) the feed composition (2) containing substantial portions of tin and lead and comprising at least 0.16% by weight and optionally at most 10% by weight of the total chromium (Cr), manganese (Mn), vanadium (V), titanium (Ti), tungsten (W), copper (Cu), nickel (Ni), iron (Fe), aluminum (AI) and / or zinc (Zn), the feed composition (2) being available at a temperature of at least ten at least 500 ° C, the pre-treatment step comprising the steps of:
BE2017 / 5681
b) cowing (200) the feed composition (2) to a temperature of up to 825 ° C to produce a bath containing a first supernatant scratch (9) which floats on a first liquid melt by gravity
5 metal phase (3),
c) adding (300) an alkali metal and / or an alkaline earth metal, or a chemical compound comprising an alkali metal and / or an alkaline earth metal (13), to the first liquid molten metal phase (3) to form a bath
10 containing a second supernatant scratch (10) floating by gravity on top of a second liquid molten metal phase (4), and
d) removing the second scratch (10) from the second liquid molten metal phase (4),
Wherein the liquid molten metal phase (6) obtained as a product of the pretreatment forms the metal mixture according to any one of the preceding claims, the method further comprising the step of subjecting the metal mixture (6) to a distillation step (600) wherein lead ( Pb) from it
Metal mixture is removed by evaporation and a bottom product (8) is obtained which comprises at least 0.6 wt.% Lead.
[19]
The method of the preceding claim comprising the step of removing the first supernatant scratch (9) from the bath before step c).
25
[20]
The method according to any one of claims 18-19, wherein the method of obtaining the feed composition (2) comprises a metal melting step and wherein at least one of the removed scratches (9,10,11,12) is recycled to the melting step.
BE2017 / 5681
[21]
The method according to any one of claims 18-20, wherein in step c) the alkali metal and / or the alkaline earth metal (13) is added in a chemically bonded form, preferably as a solid.
[22]
The method according to any one of claims 18-21, wherein the alkali metal and / or the alkali metal (13) is added as an oxide or a hydroxide, preferably as a hydroxide.
[23]
The method according to any one of claims 18-22, wherein sodium hydroxide is added in step c).
[24]
The method according to any one of claims 18-23, wherein the feed composition (2) contains at least 0.0010 wt% zinc (Zn) and wherein, together with an oxygen source, an ignition source is provided above the bath during and / or after the addition of the alkali metal and / or the alkaline earth metal.
[25]
The method of any one of claims 18-24, wherein the second liquid molten metal phase (4) is at least 100 ppm wt. copper and wherein sulfur (14) is added to the bath formed in step c).
[26]
The method of any one of claims 18-25 wherein the feed composition (2) comprises copper and the method comprises the step of adding sulfur (14) to the product (4) of step d) in at least the stoichiometric amount that necessary to react with the amount of copper (Cu) present.
[27]
The method of claim 24 or any of claims 25-26 when dependent on claim 24 wherein the ignition source (13) is provided above the bath by adding elemental sulfur to the atmosphere above the bath.
[28]
The method of any one of claims 25-27 wherein a third scratch (11) is formed after the sulfur addition (400), the method further comprising removing the third scratch (11) from the bath.
BE2017 / 5681
[29]
The method of the preceding claim, wherein, after the removal of the third scratch (11), an amount of sodium hydroxide (15) is added (500) to the bath.
[30]
30. The method of the preceding claim, wherein, after the addition of the NaOH (15), an ignition source is provided above the bath.
[31]
The method of any one of claims 18-30, wherein a silicon source is added to the bath.
[32]
32. The method of any one of claims 18-31, wherein the distillation step (600) is performed in continuous operation mode.
[33]
The method of any one of claims 18-32 wherein the distillation step (600) is performed at a pressure of up to 15 Pa absolute.
[34]
34. The method of any one of claims 18-33 wherein the distillation step (600) is performed at a temperature of at least
800 ° C.
[35]
The method according to any one of claims 18-34, which is monitored and / or controlled at least partly electronically, and preferably by a computer program.
BE2017 / 5681

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法律状态:
2018-06-15| FG| Patent granted|Effective date: 20180425 |

优先权:

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申请号 | 申请日 | 专利标题

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EP16190907.2|2016-09-27|

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EP16190907|2016-09-27|

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