method for processing mineral material containing carbonate that consumes acid and precious metal in

专利摘要:
METHOD FOR PROCESSING MINERAL MATERIAL CONTAINING CARBONATE THAT CONSUMES ACID AND PRECIOUS METAL IN SULPHIDE MINERALS. Mineral material process containing precious metal with one or more sulphide minerals and non-sulphide gangue minerals that include acid-consuming carbonate may include preparation of a sulfite concentrate by flotation or conditioning prior to flotation using a gas that comprises carbon dioxide. The fluctuation can be at an acidic pH without prior to the decomposition of the acid-consuming carbonate and can be without the addition of acid to adjust the pH.
公开号:BR112015027415B1
申请号:R112015027415-3
申请日:2014-04-23
公开日:2021-02-09
发明作者:Ronel Du Plessis Kappes；James Nicholas Orlich；John C. Gathje
申请人:Newmont Usa Limited；
IPC主号:

专利说明:

Related Order Reference
[0001] This application claims the benefit of US Provisional Patent Application No. 61 / 817,781, filed on April 30, 2013, the complete contents of which are incorporated here as defined here in their entirety. Field of the Invention
[0002] The present invention relates to the process of refractory precious metal sulphide mineral materials containing acid-consuming carbonate, including in relation to conditioning before flotation, flotation to prepare a sulfide concentrate and post-flotation concentrate processing sulfide including oxidative treatment to expose precious metal to leaching. Technique History
[0003] Significant amounts of precious metal, especially gold, are found scattered in pyritic sulfide minerals, such as for example pyrite, Marcasite, pyrrhotite, arsenopyrite and / or arsenic pyrite. Generally, very little gold contained in these sulfide minerals is recoverable by direct leaching with cyanide or other gold leachers. Instead, it is typically necessary to decompose the sulfide minerals to a significant extent in order to expose the gold and make the gold available for leaching. The decomposition of the sulfide mineral can involve oxidative treatment, for example, oxidation or pressure biooxidation. Processing may include preparing a sulfide concentrate by flotation prior to oxidative treatment. The preparation of a concentrate reduces the amount of material that can be processed in the oxidative treatment and provide higher concentrations of sulfur sulfide that can be beneficial to incite the desired reactions during some oxidative treatment techniques. For example, an oxidative treatment is acid pressure oxidation in which a sulfide-containing mineral material, such as an ore, concentrate or ore / concentrate mixture, comes into contact with oxygen in an autoclave at an elevated temperature and pressure in an environment acid. In the autoclave, the oxygen gas reacts with sulfur sulfide which results in the decomposition of sulfide minerals and the generation of sulfuric acid. The oxidation of sulfur sulfide is exothermic and the process can be thermally autogenous as long as the feed contains a sufficiently high concentration of sulfur sulfide to generate adequate heat and sufficiently high acid concentrations.
[0004] Some ores contain significant amounts of acid-consuming carbonate that complicate processing. Many carbonate minerals, for example calcite, magnesite, siderite and dolomite, will react with sulfuric acid which results in carbonate decomposition, the generation of carbon dioxide and the formation of sulfate salts. A small amount of carbonate that consumes acid in mineral material fed to the acid pressure oxidation feed may be acceptable, however as the carbonate concentrations become higher the consumption of sulfuric acid by the carbonate can be a significant damage to the oxidation pressure operation. One way to treat the high concentrations of carbonate material in sulfide ores to be oxidized by pressure is to pre-treat the ore with sulfuric acid to decompose the carbonates before being fed to the pressure oxidation autoclave, so that the carbonate it will not be available to react in the autoclave and therefore will not interfere with desired reactions during pressure oxidation. However, the cost of sulfuric acid consumed in such a pretreatment operation can be significant. For ores with high concentrations of gold, the cost of pretreatment may be justified, but for many ores containing carbonate the said pretreatment can be prohibitive even with carbonate levels that are in the range of one percent of weight, or even less in some cases.
[0005] The carbonate content in an ore can also be a significant problem for the processing of flotation to prepare a sulfide concentrate for oxidative treatment. For many gold sulfide ores, flotation to prepare a sulfide concentrate may be most effective if carried out at an acidic pH, and the semi-fluid flotation feed masses are adjusted to the desired acidic pH by adding acid, commonly acidic. sulfuric. However, when the ore contains significant acid-consuming carbonate, the significant acid is consumed to decompose the carbonate before the pH of the ore slurry can be effectively adjusted to the desired acidic pH for flotation. In addition, as a result of acidification, precipitates may form that are too small in size to complicate flotation and post-flotation filtration of flotation concentrates, as well as causing the filter to fit. Especially when the mineral material contains significant carbonate that consumes acid in the form of calcite, very fine particles of calcium sulfate precipitate (gypsum) may form. The presence of said precipitates during flotation can interfere with flotation performance, which may lead to the need to flotate at a lower density of mud solids. Also, the presence of said precipitates in the flotation concentrate can interfere with the effective dehydration of flotation concentrates, such as by filtration. The filtration fitting can become a significant problem as a result of said very fine precipitates. Summary of the Invention
[0006] The processing of refractory precious metal sulfide mineral materials that contain acid-consuming carbonate is revealed in which the mineral material can be subjected to acid flotation to prepare a sulfide concentrate without the need to decompose the carbonate from the material mineral before flotation. As used here, precious metal refers to gold, silver or gold and silver, whether other valuable components may or may not be present. A sludge containing mineral material feed can be beneficially adjusted to an acidic pH for sulfide flotation through the use of a gas containing carbon dioxide. The carbon dioxide in the gas can dissolve in the mud liquid and form carbonic acid and reduce the pH of the mud, and only with small or negligible carbonate decomposition. Carbon dioxide treatment tends to reduce the sludge to a slightly acidic pH and unexpectedly impart other beneficial properties to the sludge that are favorable for effective flotation to prepare a sulfide concentrate. For example, it appears that using carbon dioxide can result in the beneficial treatment of sulphide mineral surfaces, which may include removing or reducing the presence of at least some surface aspects that may interfere in some way with flotation performance. Examples of some of these aspects of the surface may include hydroxides and surface oxides and materials that contain absorbed calcium or magnesium. The presence of said calcium and magnesium-containing materials can be of particular concern when processing mineral materials that contain acid-consuming carbonate, because the carbonate is usually in minerals with calcium and / or magnesium which provides a significant source of these materials for possible harmful interaction with sulphide mineral surfaces. Also, dissolved calcium and magnesium that accumulate in process water can be a source for those materials that can interact in a harmful way with sulphide mineral surfaces. Several aspects of processing including the use of carbon dioxide are revealed here.
[0007] A first aspect involves a method for processing mineral material containing precious metal associated with one or more sulphide minerals and non-sulphide gangue minerals, with the method comprising flotation processing including flotation of the mineral material in liquid medium aqueous at a pH less than pH 7 with flotation gas to prepare a flotation concentrate enriched in sulfide minerals and the precious metal relative to the mineral material as fed for flotation and a decantate enriched in non-sulfide gangue minerals relative to mineral material as fed for flotation. Flotation processing includes at least one of the following:
[0008] (i) the flotation gas comprises at least 5% by volume of carbon dioxide; and
[0009] (ii) before flotation, conditioning the mineral material, which comprises treating a sludge including the mineral material with a conditioning gas comprising at least 5% by volume carbon dioxide.
[0010] A number of improvements to aspects and additional aspects are applicable to this first aspect. These refinements of aspects and additional aspects can be used individually or combined within the subject of the first aspect or any other aspect of the disclosure. As such, each of the following aspects can be, but need not be, used within any other aspect or combination of aspects of the first aspect or any other aspect.
[0011] The method of the first aspect is particularly advantageous for the processing of mineral material in which the non-sulfide gangue minerals comprise acid-consuming carbonate. As such, the description below is provided in the context that the mineral material being processed includes carbonate that consumes acid, although it is not necessary for all processing variations of this first aspect.
[0012] Flotation can be performed at a suitable acidic pH. In some processing variations, flotation can be carried out at a pH not exceeding a pH of 6.5, not exceeding a pH of 6.4, not exceeding a pH of 6.3, not exceeding a pH of 6.2, not exceeding pH 6.1, not exceeding pH 6.0, not exceeding pH 5.9, not exceeding pH 5.8 or not exceeding pH 5.7. In some processing variations, flotation can be carried out at a pH not less than pH 5, not less than pH 5.1, not less than pH 5.2, not less than pH 5.3, not less at pH 5.4 or not less than pH 5.5. The method can be essentially in the absence of pH adjustment with the addition of sulfuric acid, or with the addition of any other acid. The pH adjustment before or during flotation can be carried out essentially in the absence of acid addition to the sludge, and can be due mainly to or even essentially or entirely to the use of carbon dioxide in the flotation gas and / or flue gas. conditioning. Not being bound by theory, carbon dioxide can dissolve in an aqueous sludge liquid to generate carbonic acid in a sludge liquid that lowers the pH of the sludge liquid, without adding acid (eg, sulfuric acid) to the sludge and a mud liquid tends to stabilize at slightly acidic pH in a relatively narrow pH range suitable for flotation. The flotation pH below pH 5 can be used, however operating at said low pH's may involve higher rates of carbon dioxide spray, higher concentrations of carbon dioxide in the flotation gas and / or maintain a positive head pressure during flotation to increase the partial pressure of carbon dioxide in the system.
[0013] In some preferred processing variations, the method may include conditioning before flotation. During conditioning, a sludge including mineral material can be treated with a conditioning gas that comprises at least 5% by volume of carbon dioxide. It has been found that including conditioning is particularly beneficial in helping to prepare the mineral material for effective flotation. During conditioning, the pH of the mineral material can be adjusted to a suitable acid pH in the preparation for flotation and the surfaces of sulphide mineral grains can be cleaned to promote good flotation of sulphide mineral species. Due to the presence of carbonate minerals in the mineral material, the sludge will generally have a natural pH in an aqueous sludge that is basic. Conditioning may include reducing the pH of the sludge by at least 0.5 pH unit, at least 0.7 pH unit, at least 1 pH unit, at least 1.2 pH units or at least 1, 5 pH units. Conditioning may include reducing the pH of the sludge by no more than 3.5 pH units, no more than 3 pH units, no more than 2.5 pH units or no more than 2 pH units . Conditioning may include reducing the pH of the sludge from a first pH that is greater than pH 8, greater than pH 7.5, greater than pH 7, greater than pH 6.5 or greater than pH 6.3 up to a second pH not exceeding pH 6.5, not exceeding pH 6.4, not exceeding pH 6.3, not exceeding pH 6.2, not exceeding pH 6.1, no more than pH 6.0, not more than pH 5.9, not more than 5.7 or not more than 5.6, provided that the second pH is lower than the first pH. The second pH can be at least pH 5, at least pH 5.1, at least pH 5.2, at least pH 5.3, at least pH 5.4 or at least pH 5.5. The first pH may not be higher than pH 9, not higher than pH 8.5 or not higher than pH 8. The sludge may be at the second pH at the end of conditioning. During conditioning, the conditioning gas can be contacted by the sludge to promote the dissolution of carbon dioxide in the sludge liquid. Any device and technique can be used to intimately contact the conditioning gas with the sludge. For example, the conditioning gas can be sprayed on the mud during conditioning. As another example, the conditioning gas can be mixed with the sludge in an in-line mixer, for example in-line in a conduit in which the sludge is flowing and into which the conditioning gas can be injected to contact the mud. The carbon dioxide can be mixed with the slurry under pressure to increase the dissolution of carbon dioxide in the slurry liquid (e.g., flowing in a pressure conduit or in a pressurized mixing vessel). It has been found that as carbon dioxide conditioning continues, the sludge will stabilize at a relatively constant pH, usually within a few to a few minutes. Treatment may include spraying or in some way introducing the conditioning gas into the mud for a time of at least 2 minutes, at least 5 minutes or at least 10 minutes. The time can generally be less than 40 minutes, less than 30 minutes, or less than 20 minutes. When processing does not include conditioning, the mineral material can be fed to flotation at said first pH and the pH can be rapidly reduced to said second pH due to the carbon dioxide in the flotation gas.
[0014] Importantly, the pH reduction of the slurry during conditioning can be carried out without any, or essentially in the absence of addition, sulfuric acid or other acid to the sludge. The reduction in pH may be due mainly or essentially to the carbon dioxide in the conditioning gas, which generates carbonic acid when dissolved in the aqueous liquid of the sludge. The pH in the mud may tend to stabilize at a relatively constant pH that is slightly acidic. During conditioning, at least a portion of the carbon dioxide in the conditioning gas will be consumed by dissolving it in the mud liquid. In some preferred processing variations, the concentration of carbon dioxide in the conditioning gas can be high enough that all carbon dioxide will not be consumed by the sludge, and the effluent gas outside the sludge still contains at least some carbon dioxide.
[0015] As part of the conditioning, or before or after conditioning, one or more other flotation reagents can be added to the sludge. Said reagents may include, for example, collectors, promoters, foaming agents, activators and / or depressants. Preferred collectors include xanthate collectors (e.g., amyl potassium xanthate).
[0016] The conditioning gas can comprise more than 5% by volume of carbon dioxide. The conditioning gas can comprise at least 10% by volume of carbon dioxide, at least 15% by volume of carbon dioxide, at least 25% by weight of volume of carbon dioxide, at least 50% by volume of carbon dioxide carbon, at least 75% by volume of carbon dioxide, at least 85% by volume of carbon dioxide, at least 95% by volume of carbon dioxide, or even at least 99% by volume of carbon dioxide. The conditioning gas may consist of or consist essentially of carbon dioxide. Typically, however, it is not necessary that 100% carbon dioxide be used for the conditioning gas. In some other processing variations, the conditioning gas may comprise no more than 75% by volume of carbon dioxide, no more than 50% by volume of carbon dioxide, no more than 25% by volume of carbon dioxide carbon, no more than 20% by volume of carbon dioxide gas or no more than 15% by volume of carbon dioxide. The conditioning gas portion not composed of carbon dioxide may be provided by one or more other gas components.
[0017] Surprisingly, beneficial processing can be obtained even if the conditioning gas is a mixture of gas comprising carbon dioxide and air, which in some processing variations may consist of or consist essentially of carbon dioxide and air. The benefits provided by carbon dioxide can outweigh any harmful effects of oxygen gas in the air, such as potential surface oxidation of sulfide mineral grains.
[0018] In some processing variations, however, the amount of oxygen gas in the conditioning gas can be restricted to further reduce the potential harmful effects of oxygen gas. The conditioning gas can be formulated to comprise no more than 19% by volume of oxygen gas, no more than 18% by volume of oxygen gas, no more than 15% by volume of oxygen gas, no more than 10 % by volume of oxygen gas, not more than 5% by volume of oxygen gas, not more than 2% by volume of oxygen gas or even or even not more than 1% by volume of oxygen gas. The oxygen gas in the conditioning gas can be provided for example by mixing air with carbon dioxide gas and / or by mixing a stream of purified oxygen gas with carbon dioxide. Air includes about 20% by volume of oxygen gas, and a conditioning gas made by mixing carbon dioxide gas and air will result in a conditioning gas composition that has an oxygen gas content that is less than 20% by volume. The conditioning gas may be free of, or essentially, oxygen gas. In some processing variations, however, the conditioning gas can include significant oxygen gas, such as when the conditioning gas can be a mixture of carbon dioxide gas and air. The conditioning gas can include at least 5% by volume of oxygen gas, at least 10% by volume of oxygen gas, at least 15% by volume of oxygen gas or at least 16% by volume of oxygen gas. Even with the presence of some oxygen gas, the carbon dioxide content can sufficiently reduce the pH of the sludge and can provide a cleaning effect to clean surfaces of sulphide mineral grains.
[0019] In some preferred processing variations, the conditioning gas can be a mixture of gas including carbon dioxide and nitrogen gas. The nitrogen gas in the gas mixture can be essentially an inert component, as opposed to the reactive nature of oxygen gas in a gas mixture. The conditioning gas can comprise at least 50% by volume of nitrogen gas, at least 75% by volume of nitrogen gas, at least 80 by volume of nitrogen gas, at least 85% by volume of nitrogen gas or even at least 90 % by volume or more of nitrogen gas. The conditioning gas can be a gas mixture comprising at least 90% by volume, at least 95% by volume, at least 98% by volume or at least 99% by volume of a combination of carbon dioxide and nitrogen gas . The conditioning gas may consist of or consist essentially of carbon dioxide and nitrogen gas.
[0020] When the conditioning gas includes one or more other gas components in addition to carbon dioxide gas, for example, from air or a source of purified nitrogen gas, the conditioning gas can be introduced into the slurry in the form of a premixed gas composition including all said gas components. In some alternative variations, different gaseous components of the conditioning gas can be introduced into the sludge in separate gas streams. For example, a conditioning gas including carbon dioxide and nitrogen can be introduced into the sludge as a premixed composition including both carbon dioxide and nitrogen, or separate streams of nitrogen gas and carbon dioxide gas can be introduced separately into the slurry. mud.
[0021] In some processing variations, the conditioning gas comprising carbon dioxide and nitrogen gas can be provided by processing including combustion of a carbonaceous fuel to form a combustion exhaust gas including carbon dioxide and preparing the conditioning gas including at least a portion of the flue exhaust gas. The conditioning gas can be or consist essentially of combustion exhaust, with the removal of substantially condensable components. Condensable components can be mainly water that condenses out of the combustion exhaust when cooled below the boiling point of water. For example, complete combustion of methane can produce a gas mixture which, after condensing water, can be used as a conditioning gas and can contain, for example, approximately 12% by volume of carbon dioxide, 87% by volume of carbon dioxide. nitrogen gas and 1% by volume of several other gas components (mostly argon). As another example, coal combustion can produce a gas mixture that can be used as a conditioning gas and can contain for example approximately 21% by volume of carbon dioxide, 78% by volume of nitrogen gas and 1% by volume of several other components (mostly argon).
[0022] In some preferred processing variations, the conditioning gas may consist of or consist essentially of carbon dioxide (e.g., essentially pure carbon dioxide). In some other preferred processing variations, the conditioning gas may consist of or consist essentially of only carbon dioxide and inert gas, which may be, for example, nitrogen gas.
[0023] In some processing variations, the conditioning gas can be provided by the decomposition of carbonate from mineral material containing carbonate to generate carbon dioxide and prepare the conditioning gas to include at least a part of that carbon dioxide. For example, the carbonate-containing mineral material may be a separate material containing precious metal, such as a gold sulfide ore that contains carbonate being pre-treated with acid before acid oxidative treatment. As another example, processing may include calcination of carbonate-containing material (e.g., calcite, limestone, dolomite) to produce carbon dioxide gas. In some preferred variations, processing may include liming calcination to prepare lime (CaO). Lime can be beneficially used to neutralize acid generated in operations, just as it can be generated during oxidative pretreatment of sulfide ores and concentrates (e.g., pressure oxidation, biooxidation).
[0024] In some preferred processing variations, at least some components of carbon dioxide and / or other gases (eg, nitrogen gas) of the conditioning gas can be provided by recycling from effluent gas recovered from operations of conditioning and / or flotation. Carbon dioxide recycling can significantly reduce the requirement to provide a recent supply of carbon dioxide for use to prepare flotation and / or conditioning gases. Carbon dioxide recycling may involve separating carbon dioxide from a gas effluent from conditioning and / or flotation operations and recycling a separate carbon dioxide stream, or it may involve recycling a gas mixture recovered from conditioning and / or flotation operations with or without treatment or composition adjustment before recycling. The additional fresh carbon dioxide composition can be added as needed to compensate for carbon dioxide consumption, bleeding system losses.
[0025] When the method includes conditioning, the flotation gas may or may not also contain carbon dioxide. The flotation gas can be, for example, or consist essentially of nitrogen gas, air or other gas mixtures that do not contain carbon dioxide or that contain carbon dioxide in a concentration of less than 5% by volume. However, in some preferred processing variations, the flotation gas comprises at least 5% by volume of carbon dioxide, whether or not conditioning is carried out prior to flotation. In some preferred processing variations, however, the flotation gas comprises no more than 19% by volume of oxygen gas, no more than 15% by volume of oxygen gas, no more than 10% by volume of oxygen gas , not more than 5% by volume of oxygen gas, not more than 2% by volume of oxygen gas or not more than 1% by volume of oxygen gas, or for the flotation gas to be free of or essentially free of oxygen gas. With respect to the conditioning gas, when the flotation gas includes an oxygen gas component, the oxygen gas can be provided by mixing the air or by mixing an oxygen gas stream with one or more other gases to be included in the flotation gas composition. . In some variations when the flotation gas does not include carbon dioxide, the flotation gas may consist of or consist essentially of nitrogen gas or other inert gas (e.g., argon). In some particularly preferred processing variations, the flotation gas may comprise carbon dioxide at least in a concentration sufficient to maintain a desired pH during flotation. Flotation gas and conditioning gas do not have to be the same composition. For example, the sludge may already have a desired acidic pH before flotation as a result of conditioning, and the flotation gas may only need a lower concentration of carbon dioxide to maintain a suitable acidic pH, as opposed to the conditioning gas that it may involve higher consumption of carbon dioxide to reduce the pH of the sludge from a basic pH to an acidic pH for flotation. For purposes of operational convenience, flotation gas and conditioning gas can have the same concentration. The processing including or not conditioning before flotation, the flotation gas preferably includes at least 1% by volume of carbon dioxide and more preferably at least 5% by volume of carbon dioxide. The flotation gas can have a greater, equal or lesser volume% of carbon dioxide compared to the carbon dioxide content of the conditioning gas. In some preferred processing variations, the flotation gas may have a carbon dioxide content that is equal to or that is less than the carbon dioxide content in the conditioning gas. For processing variations when a flotation gas is used that comprises at least 5% by volume of carbon dioxide, the flotation gas can have any of the compositions or properties previously described for the conditioning gas, and the flotation gas and the conditioning gas can be selected independently from said compositions. In some preferred processing variations, the flotation gas consists only essentially of carbon dioxide and nitrogen gas. The carbon dioxide for use in a flotation gas can be provided in any way similar to the above discussion regarding the provision of carbon dioxide for use in a conditioning gas.
[0026] In some processing variations, flotation gas can include at least 5% by volume of carbon dioxide and at least 80% by volume of air, at least 85% by volume of air or even at least 90% in volume of air. The carbon dioxide can be in sufficient quantity to maintain a desired pH and can assist in keeping the sulfide mineral grains relatively clean during flotation. However, the high concentration of air in the flotation gas can provide an improved safety situation because the gas is not devoid of oxygen and poses a reduced risk to people in the event of a flotation gas release to the environment. Also, since at least some carbon dioxide can be consumed by dissolving it in the flotation sludge, the effluent gas from the flotation can have a higher concentration of oxygen gas than the flotation gas feed. Also, air is readily available and the use of some air reduces the requirements for providing a first carbon dioxide gas.
[0027] In situations where flotation includes multiple stages of flotation (e.g., rougher, cleaner, remover), carbon dioxide may be used in none, some or all stages of flotation. Likewise, if the flotation includes multiple parallel flotation trains, the carbon dioxide flotation gas can be used on none, some or all of the parallel trains. In some preferred processing variations, when the flotation gas comprising at least 5% by weight of carbon dioxide is used, the flotation gas for all stages of flotation comprises at least 5% by weight of carbon dioxide, despite Although the concentration of carbon dioxide and the composition of flotation gas can be, however, it need not be the same at all stages. Likewise with multiple parallel flotation trains, when the flotation gas comprising at least 5% by weight of carbon dioxide is used in a parallel train, the flotation gas comprising at least 5% by weight of carbon dioxide may be used on all parallel trains, and the concentration of carbon dioxide and the composition of flotation gas can be, however it need not be the same on all trains.
[0028] When processing includes conditioning, if the conditioning includes multiple stages or multiple parallel conditioning trains, the conditioning gas in one, some or all of the stages or trains can contain at least 5% by volume of carbon dioxide , and the conditioning gas compositions in the stages or trains may or may not be the same or include the same gas composition.
[0029] An important advantage of the method is that mineral materials that contain significant amounts of acid-consuming carbonate can be flotated at an acidic pH to prepare a bulky sulfide concentrate without removing the acid-consuming carbonate before flotation. Importantly, during flotation, very little or none of the acid-consuming carbonates can be broken down. In addition to not consuming acid through the reaction with carbonates, avoiding the decomposition of carbonates it also tends to reduce the amount of dissolved components such as calcium and magnesium that can interact in a harmful way with sulfide surfaces during flotation. Also, there will be a reduced potential for the formation of precipitates, such as calcium sulfate precipitates, which can interfere with flotation or with flotation concentrate post-flotation filtration. Also, the neutralization requirements in the resulting flows can be beneficially reduced. Not only is the pH of the sludge not generally reduced to such a low pH using carbon dioxide compared to conventional flotation with the addition of acid, but also in the case of using carbon dioxide the pH of the processed liquid will tend to naturally increase as a result of carbon dioxide being released from solution as the introduction of carbon dioxide into a sludge is discontinued. The increase in pH can be accelerated and increased by bubbling gas, such as air or nitrogen, through the liquid to help peel carbon dioxide out of the liquid. For example, lime or other base addition requirements to increase the pH of disposal of flotation tails or at an alkaline pH for cyanide or other gold leaching can be significantly reduced compared to conventional flotation practice using sulfuric acid to acidify liquid of mud for flotation. This benefit is, in addition, the reduction or elimination of requirements for the addition of sulfuric acid before flotation in relation to the practice of conventional flotation. The bleeding liquid from the flotation operation may likewise have minor neutralization requirements. In some processing variations, the pH of the flotation tails can be increased by at least 0.3 unit of pH, at least 0.5 unit of pH or even at least 1 unit of pH as a result of removal of carbon dioxide from the liquid associated with the tails. In some processing variations, the tails can be subjected to gold leaching following a said pH increase and any additional desired pH adjustment for gold leaching. Gold leaching may involve leaching by any gold leacher, for example, cyanide, thiosulfide or thiocyanate leachers. In some implementations, a gold leach can be performed at a pH of at least pH 8.
[0030] In some processing variations, no more than 10 percent, no more than 5 percent or no more than 1 percent of the acid consuming carbonate can be decomposed during flotation. In some processing variations, during flotation at least a majority, and generally most, of the carbonate that consumes acid fed for flotation can be recovered in the decantate, and the flotation concentrate may contain smaller amounts, if any, of carbonate that consumes acid. The flotation concentrate can then be further processed, such as by oxidative treatment, without charge of the total amount of carbonate that consumes acid in the mineral material as fed to the flotation. In some processing variations, at least 60% by weight, at least 70% by weight or at least 80% by weight of the carbonate that consumes acid fed for flotation can be recovered in the decanted. In other processing variations, the carbonate that consumes acid fed for flotation can communicate in relatively equal proportions for the flotation concentrate and the decantate or even a majority of the carbonate that consumes acid can communicate for the flotation concentrate. Even in situations where a majority of the carbonates do not communicate with the decanted, the flotation concentrate will still be properly concentrated in the desired precious sulfide and metal minerals.
[0031] The method can advantageously process mineral materials that contain a range of carbonate contents that consume acid and can process mineral materials that contain large concentrations of carbonate that consumes acid. The mineral material as fed to the flotation may comprise at least 0.1% by weight, at least 0.25% by weight, at least 0.5% by weight, at least 1% by weight, at least 2% by weight at least 3% by weight, at least 4% by weight or even at least 5% by weight or more of acid-consuming carbonate. The mineral material as fed to the flotation may comprise not more than 50% by weight, not more than 40% by weight or still not more than 30% by weight of acid-consuming carbonate. The mineral material as fed for flotation may have a significant acid consumption capacity, as determined by the amount of sulfuric acid needed to break down all or essentially all acid-consuming carbonates. In some processing variations, the method can be carried out essentially in the absence of contact with the mineral material with sulfuric acid during or before flotation. The ore may have an acid consumption capacity of at least 0.25, at least 0.5, at least 1, at least 2, at least 5, at least 10 or at least 20 kg of sulfuric acid per ton of mineral material, as determined by the amount of sulfuric acid needed to form an aqueous slurry with the mineral material at a pH of 5.5 for flotation processing.
[0032] In some preferred processing variations, most or essentially all of the acid-consuming carbonate fed into the flotation can be recovered in the flotation concentrate and the decant, so that the decant and the flotation concentrate together can comprise at least at least 0.1% by weight, at least 0.5% by weight, at least 1% by weight, at least 2% by weight, at least 3% by weight, at least 4% by weight or at least 5% in weight or more of acid consuming carbonate, in relation to the combined weight of the decanted and the flotation concentrate. The flotation concentrate and the decanted together can generally comprise no more than 50% by weight, no more than 40% by weight or no more than 30% by weight of acid consuming carbonate, with respect to the combined weight of the decanted and the flotation concentrate.
[0033] In some processing variations, the acid-consuming carbonate content of a material (eg, mineral material feed for conditioning or flotation, flotation concentrate or decanted) can refer to carbonate in the material that will decompose if the mineral material is impregnated with water and acidified with sulfuric acid to obtain an acidified sludge with a reasonably stable acidic pH not exceeding a pH of 5.5.
[0034] Carbonate that consumes acid can be present in a variety of carbonate minerals. Many of these carbonate minerals may contain group 2 metals (alkaline earth metals), and particularly calcium and / or magnesium, such as for example in dolomite, calcite or magnesite. In some processing variations, the mineral material when fed for flotation may comprise at least 1% by weight, at least 2% by weight, at least 2.5% by weight, at least 3% by weight, at least 3, 5% by weight, at least 5% by weight, or at least 8% by weight, at least 10% by weight, at least 15% by weight or at least 20% by weight or more of carbonate minerals containing calcium and / or magnesium, which in some processing variations can be selected from the group consisting of dolomite, calcite, magnesite and siderite; they can be selected from the group consisting of dolomite, calcite and magnesite or they can be selected from the group consisting of dolomite and calcite. In some processing variations, any one of dolomite, calcite, magnesite or siderite may be present in the mineral material in such when fed for flotation. In some processing variations, the mineral material as fed for flotation may include significant amounts of calcium and / or magnesium, which may be at least 0.5% by weight, at least 1% by weight, at least 2% by weight at least 3% by weight, at least 5% by weight or at least 10% by weight or more of combined calcium, magnesium or magnesium and calcium contained in carbonate minerals.
[0035] The mineral material as fed for flotation may comprise a significant amount of sulfide minerals, at least some of which contain precious metal, which may be or include gold. The mineral material can comprise at least 0.5% by weight of sulfur sulfide, at least 1% by weight of sulfur sulfide, at least 1.5% by weight of sulfur sulfide or at least 2% by weight of sulfide sulfur. The mineral material can generally include no more than 5% by weight of sulfur sulfide, no more than 4% by weight of sulfur sulfide or no more than 3% by weight of sulfur sulfide. Flotation can be a mass flotation of sulfide with a majority of sulfide minerals by weight being recovered in the flotation concentrate. Bulk sulphide flotation is distinguished from selective sulphide flotation in which a sulphide mineral must be selectively floated in relation to a different sulphide mineral which must be depressed during flotation to effect a separation between the different sulphide minerals . In some processing variations the recovery of sulfur sulfide in the concentrate can be at least 70 percent, at least 80 percent, at least 85 percent or at least 90 percent. The mineral material may be a refractory sulfide precious metal ore, a mixture of ore or a portion of said ore or mixture of ore. The precious metal can include gold and / or silver.
[0036] The method can be particularly advantageous for processing mineral materials containing gold, in which a significant amount of the gold is refractory gold (not conducive to direct cyanide leaching) contained in sulphide minerals which have a high susceptibility to oxidation and tend to to be difficult to float. As summarized in U.S. Patent No. 6,210,648, some refractory sulfide minerals that contain gold are sulfides that contain iron and arsenic. For example, arsenopyrite (FeAsS) may contain gold in its mineral structure. Other examples are arsenic iron sulfides, such as arsenic pyrite, arsenic marcaite and arsenic pyrrhotite. These arsenic iron sulphides have some differences in composition related to the corresponding pure minerals (eg, pyrite, Marcasite and pyrrhotite) in which the arsenic iron sulphides include arsenic in the mineral structure in such a way that it also allows the inclusion of gold in the mineral structure. Arsenic provides irregularity in the mineral structure relative to pure iron sulfide minerals. The irregularity offers space within the mineral sulfide structure to accommodate the presence of gold atoms, but it also increases the susceptibility of arsenic iron sulfides to oxidation in the presence of air and to galvanic interaction, both of which are harmful to the flotation of those sulfide species. Much of the gold in ores from the Carlin area in the state of Nevada (USA) is contained in the so-called arsenic iron sulfides. Some other refractory sulfides that contain gold are arsenic-rich sulfide species, such as those based on auripigment and enhancement, which may include small amounts of iron in the mineral structure that provides irregularity to allow the inclusion of gold. In order to improve flotation recovery, especially of gold-containing sulfide species that are highly susceptible to oxidation, such as arsenic iron sulfides, U.S. Patent No. 6,210,648 proposes processing in which the ore being processed The processed product can be kept in an environment that is substantially free of oxygen starting with the comminution of the ore and ending with the recovery of the desired sulfide concentrate produced by flotation.
[0037] With the method of the first aspect of this disclosure, the mineral material as fed for flotation may comprise at least 1% by weight, at least 2% by weight or at least 3% by weight of sulfide minerals containing iron, at least some of which may contain precious metal, and the flotation concentrate can be enriched in the sulfide minerals that contain iron in relation to the mineral material as fed into the flotation. The mineral material as fed to the flotation can generally comprise not more than 10% by weight, not more than 7% by weight, or not more than 5% by weight of sulfide minerals that contain iron. The mineral material as fed for flotation can comprise at least 0.5% by weight of sulfide minerals, some or all of which may contain precious metal, which comprises both iron and arsenic and the flotation concentrate can be enriched in said minerals of sulfide in relation to the mineral material as fed for flotation. The mineral material as fed for flotation may comprise at least 0.5% by weight of sulphide minerals, some or all of which may contain precious metal selected from the group consisting of arsenopyrite, arsenic pyrite, arsenic pyrrhotite, arsenic trademark and combinations thereof and the flotation concentrate can be enriched in sulfide minerals in relation to the mineral material as fed to the flotation. The mineral material as fed for flotation may comprise at least 0.3% by weight of arsenic iron sulfides, some of which or all of which may contain precious metal and which in some processing variations may be selected from the group which consists of arsenic pyrite, arsenic marcaite and arsenic pyrrhotite, and the flotation concentrate can be enriched in the said arsenic iron sulfides in relation to the mineral material as fed to the flotation. The mineral material as fed for flotation can comprise at least 500, at least 1000, at least 1500 or at least 2000 parts per million by weight of arsenic and the flotation concentrate can be enriched in arsenic in relation to the mineral material as fed for flotation. The mineral material as fed for flotation may comprise at least 0.3% by weight of sulphide minerals, some of which or all of which may contain precious metal, selected from the group consisting of arsenopyrite, arsenic pyrite, pyrrhotite of arsenic, arsenic marcaite and combinations thereof and the flotation concentrate can be enriched in sulfide minerals that contain precious metal in relation to the mineral material as fed for conditioning. The mineral material as fed for flotation can comprise at least 0.2 parts per million by weight of gold or at least 0.5 parts per million by weight of gold, and the flotation concentrate can be enriched in gold relative to the material mineral as fed for flotation.
[0038] Advantageously, the elimination of oxygen from processing with the method of the first aspect may not be necessary, as noted previously. Comminution before flotation or conditioning can be carried out in air, and can be carried out in the absence of an oxygen deficient cover gas, in the absence of sealed comminution equipment and / or in the absence of removal of dissolved oxygen from the process water before using process water to form a slurry with the mineral material for processing in conditioning or flotation.
[0039] The flotation can be carried out advantageously effectively even when the liquid medium during the flotation contains dissolved calcium and / or significant magnesium. This is important because calcium has the potential to interact with sulphide mineral surfaces, and especially iron sulphide mineral surfaces, in such a way that it may tend to depress the flotation of some or all of the sulphide minerals. For example, calcium reagents are sometimes used in flotation operations to depress pyrite, for example in selective flotation operations where another sulfide is being selectively recovered from pyrite. For example, in some processing variations, the liquid medium during flotation may comprise a concentration of calcium or magnesium, or a combined concentration of calcium and dissolved magnesium, of at least 500 milligrams per liter. This may allow the use of a wider range of process water and / or with fewer additions of reagents to counteract the depressive effects that calcium and / or magnesium may have during flotation. Flotation processing can be carried out essentially in the absence of the addition of a reagent containing calcium.
[0040] When the method includes conditioning, conditioning can be carried out with little or even no decomposition of the acid-consuming carbonate. During conditioning, and during both conditioning and flotation, no more than 10 percent, no more than 5 percent, or even no more than 1 percent of the acid-consuming carbonate can be decomposed. The mineral material as fed for conditioning may have any of the compositions or other properties described above for the mineral material as fed for flotation, and the mineral material may have any said composition or other properties before and after conditioning and as fed for flotation.
[0041] In some processing variations, the method of the first aspect may include separate processing of flotation of fractions with different sizes of a mineral material feed. This can be particularly beneficial for processing mineral materials including significant gold contained in arsenic iron sulphides, because those sulphides tend to be more concentrated in smaller sized particles after comminution. The recoveries of said particles of smaller size in flotation concentrate can be improved by separating the mineral material feed into fractions of different particle sizes that are subjected to flotation separately. This can allow larger particles to be flotated at a higher mud density and smaller particles to be flotated at a lower mud density that is favorable for better recovery of the smaller particles. This can also help to reduce drag losses of smaller particles. In some situations, the method may include separating by size a mineral material feed into at least two fractions, with a first fraction having a smaller particle size of medium weight and a second fraction having a larger particle size of weight average. The mineral material feed may have a precious metal associated with one or more sulphide and non-sulphide gangue minerals including acid-consuming carbonate, and may have any compositional or other properties described above. Each of the first fraction and the second fraction can include a portion of the precious metal from the mineral material feed and a portion of the acid consuming carbonate from the mineral material feed. A first mineral material including at least a portion of the first fraction can then be subjected to the first flotation processing which comprises the first flotation in aqueous liquid medium at a pH less than pH 7 and with the first flotation gas to prepare a first flotation concentrate enriched in sulphide and precious metal minerals related to the first mineral material as fed to the first flotation concentrate and a first decantate enriched in non-sulfide gangue minerals related to the first mineral material as fed to the first flotation. A second mineral material including at least a portion of the second fraction can be subjected to a second flotation processing which comprises the second flotation in aqueous liquid medium at a pH less than pH 7 with a second flotation gas to prepare a second concentrate of flotation enriched with sulfide and precious metal minerals related to the second mineral material as fed for the second flotation and a second decantate enriched with non-sulfide gangue minerals related to the second mineral material as fed for the second flotation.
[0042] The separation by size can be performed through any separation by size technique. In some processing variations, separation by size may include subjecting the mineral material feed to cyclone separation, with the first fraction or part of it being recovered with cyclone overflow and the second fraction or part of it being recovered with cyclone flow. The first fraction and / or the first mineral material can have a medium weight particle size (size P50), or it can also have a size P80, less than 30 microns, less than 25 microns, less than 20 microns, less than 15 microns or less than 10 microns. By size P80, we mean a size in which 80% by weight of the particles are that size or smaller. The average weight particle size, or P80 size, of the first fraction and / or the first mineral material can generally be at least 3 microns. The second fraction and / or the second mineral material may have a medium weight particle size, or P80 size, of at least 50 microns, at least 75 microns or at least 100 microns. The average weight particle size, or P80 size, of the second fraction and / or the second mineral material can generally be less than 500 microns.
[0043] Any one or both of the first flotation processing and the second flotation processing can be performed according to the flotation processing described above that has any aspect described above or a combination of any of said aspects. For example, any one or both of the first flotation gas and the second flotation gas can comprise at least 5% by volume, or more, carbon dioxide and any one or both of the first flotation processing and the second processing of flotation may include conditioning the first mineral material or the second mineral material, as the case may be, which comprises treatment with a conditioning gas comprising at least 5% by volume, or more, carbon dioxide. The method can include at least one of (i) the first flotation gas of the first flotation comprises at least 5% by volume of carbon dioxide; (ii) the second flotation gas of the second flotation comprises at least 5% by volume of carbon dioxide and (iii) conditioning before one or two of the first flotation and the second flotation with a conditioning gas comprising at least 5 % by volume of carbon dioxide. The first mineral material and / or the second mineral material can have any of the composition properties or any other property described above or any combination of any of said properties. When the mineral material feed for size separation includes arsenic iron sulphides, the first fraction may contain a majority by weight of the arsenic iron sulphides from the mineral material feed.
[0044] The first flotation concentrate and the second flotation concentrate can be subjected to post-flotation processing including oxidative treatment to decompose sulfide minerals and expose precious metal in the preparation for leaching of precious metal. The first flotation concentrate and the second flotation concentrate can be combined and processed together, for example, by combined biooxidation processing or combined pressure oxidation processing, which may involve acid pressure oxidation or alkaline pressure oxidation. However, a significant benefit of separation by size of a mineral material feed and separate processing of flotation of fractions with different sizes is that the first flotation concentrate prepared separately and the second flotation concentrate can be subjected to post-flotation processing separate, including separate oxidative treatment. In some processing variations, the second flotation concentrate may be subjected to post-flotation processing involving pressure oxidation (acidic or alkaline) and the first flotation concentrate may be subjected to a different oxidative treatment. The oxidative treatment other than the first flotation concentrate may include a separate pressure oxidation technique (alkaline or acidic), biooxidation or an atmospheric oxidation technique. Due to the small particle size of the first flotation concentrate, the first flotation concentrate can generally be more favorable to atomic oxidation processes, which can be acidic or alkaline. This is especially the case when the first flotation concentrate includes significant arsenic iron sulfides that contain precious metal. In some preferred processing variations, the first flotation concentrate can be subjected to atmospheric oxidative treatment which comprises contacting the first flotation concentrate with oxygen gas and a base material containing calcium. The base material containing calcium may comprise lime or limestone. This processing can benefit from the presence of carbonate minerals that can be recovered in the first flotation concentrate during the first flotation process. The chemistry of this atmospheric oxidation processing may be similar to that of neutral AlbionTM leaching, however, the first flotation concentrate may not need to be subjected to ultra-fine grinding as required by that process, because of the already small particle size of the first flotation concentrate that results from separation by size.
[0045] Another advantage of the separation by size and the separate flotation processing of the first and second flotation concentrates is that the second flotation concentrate can be filtered without complication caused by the presence of the smaller particles of the first flotation concentrate to prepare the second flotation concentrate for oxidative treatment. The smaller particles of the first flotation concentrate are more susceptible to fitting the filter. The first flotation concentrate can be filtered separately with greater control through filter parameters and filter performance, or the first flotation concentrate can be subjected to oxidative treatment essentially in the absence of filtration of the first flotation concentrate following the first flotation. Atmospheric oxidative treatment can work particularly well with the processing of the first flotation concentrate in the absence of filtration. The first flotation concentrate can have a particular weight average size as described for the first fraction from the size separation or the first mineral material as fed for the first flotation processing. Likewise, the second flotation concentrate may have a medium weight particle size as described for a second fraction from separation by size or from the second mineral material as fed for a second flotation processing.
[0046] After the oxidative treatment, the oxidative treatment residue of the first flotation concentrate and the second flotation concentrate can be subjected to leaching of precious metal, which can be a combined leaching of both combined wastes or separate leaching of each residue . Leaching of precious metal can involve leaching with any precious metal leacher, which can be a leacher for gold, such as, for example, cyanide, thiosulfide or thiocyanate.
[0047] A second aspect involves a method for processing mineral material containing precious metal associated with one or more sulphide minerals and non-sulphide gangue minerals. The method comprises conditioning in the preparation for flotation at an acidic pH, with conditioning comprising treating a sludge comprising the mineral material with a conditioning gas comprising at least 5% by volume of carbon dioxide. During treatment, the pH of the sludge is reduced by at least 0.5 pH unit to a pH that is less than pH 6.5.
[0048] A number of improvements to aspects and additional aspects are applicable to this second aspect. These refinements of aspects and additional aspects can be used individually or combined within the subject of the second aspect or any other aspect of the disclosure. As such, each of the following aspects can be, but need not be, used within any other aspect or combination of aspects of the second aspect or any other aspect.
[0049] With respect to the first aspect, the second aspect is particularly advantageous for processing the mineral material in which the non-sulfide gangue minerals comprise acid-consuming carbonate. As such, the description below is provided in the context that the mineral material being processed includes carbonate that consumes acid, although it is not necessary for all processing variations of this second aspect.
[0050] The conditioning of the second aspect may be according to the conditioning description provided with respect to the first aspect or it may have any aspect or aspects described above in relation to the conditioning with respect to the first aspect or any combination of any of said aspects.
[0051] In addition to these aspects, modalities and variations described above, additional aspects, modalities and variations will become apparent by reference to the drawings and by studying the following descriptions and examples.
[0052] Brief Description of the Drawings
[0053] Figure 1 is a generalized process block diagram that illustrates some examples of processing variations including flotation.
[0054] Figure 2 is a generalized process block diagram that illustrates some examples of processing variations including conditioning and flotation.
[0055] Figure 3 is a generalized process block diagram that illustrates some examples of processing variations including step flotation.
[0056] Figure 4 is a generalized process block diagram that illustrates some examples of processing variations including step flotation.
[0057] Figure 5 is a generalized process block diagram that illustrates some examples of processing variations including separation by size prior to flotation processing.
[0058] Figure 6 is a generalized process block diagram that illustrates some examples of processing variations including separation by size before flotation processing and flotation concentrate post-flotation processing.
[0059] Figure 7 is a generalized process block diagram that illustrates some examples of processing variations including post-flotation processing including combined oxidative treatment of flotation concentrates.
[0060] Figure 8 is a generalized process block diagram that illustrates some examples of processing variations including post-flotation processing including combined oxidative treatment of flotation concentrates.
[0061] Figure 9 is a generalized process block diagram that illustrates some examples of processing variations including post-flotation processing including separate oxidation treatment of flotation concentrates.
[0062] Figure 10 is a generalized process block diagram that illustrates some examples of processing variations including post-flotation processing including separate oxidation treatment of flotation concentrates.
[0063] Figure 11 shows plots of relative concentration as a% of initial calcium concentration in solution of semi-fluid test masses as a function of time for different ore samples during conditioning.
[0064] Figure 12 shows plots of relative concentration as a% of initial magnesium concentration in solution of semi-fluid test masses as a function of time for different ore samples during conditioning.
[0065] Figure 13 shows portions of relative concentration as a% of initial concentration of iron dissolved in solution of semi-fluid test masses as a function of time for different ore samples during conditioning.
[0066] Figure 14 shows plots of relative concentration as a% of initial sulfur concentration in solution solution in semi-fluid test masses as a function of time for different ore samples during conditioning.
[0067] Detailed Description
[0068] Figure 1 shows an illustration of an embodiment for flotation processing 100. As shown in Figure 1, flotation processing 100 includes subjecting a mineral material 102 to flotation 104 using a flotation gas 110 to prepare a flotation concentrate 106 and a decantate 108. The flotation gas 110 may be or include carbon dioxide.
[0069] Figure 2 shows a variation in the flotation processing modality 100 shown in Figure 1. As shown in Figure 2, the flotation processing 100 includes flotation 104 as described with Figure 1. In the variation in Figure 2, the material mineral 102 is subjected to conditioning 120 prior to flotation 104. In conditioning 120, mineral material 102 is treated with conditioning gas 122. One or both of the flotation gas 110 and conditioning gas 122 is or includes carbon dioxide .
[0070] Figures 3 and 4 show some examples of variations in the flotation 104 of Figures 1 and 2 including multiple stages of flotation. As shown in Figure 103, flotation 104 may include a rougher flotation stage 130, a cleaner flotation stage 132, and a flotation remover stage 134. Mineral material 102 is first subjected to rougher flotation 130 to prepare a flotation concentrate rougher 136 and a rougher decant 138. The rougher flotation concentrate 136 is subjected to cleaner flotation 132 to prepare flotation concentrate 106 and a cleaner decanter 140. The rougher decant 138 is subjected to removing flotation 134 for prepare a flotation concentrate 142 and a decantate 108. The cleaner decantate 140 and the flotation concentrate 142 are recycled for processing through the rougher flotation 130 with mineral material 102. A flotation gas 110a, 110b, 110c is used in each of the rougher flotation 130, cleaner flotation 132 and flotation remover 134. Flotation gases 110a, b, c can be the same or can be with different positions, and one or more of the flotation gases 110a, 110b, 110c can be or include carbon dioxide.
[0071] Figure 4 shows a variation for flotation 104 including a rougher flotation stage 130, cleaner flotation stage 132 and flotation remover stage 134 similar to Figure 3, except with slightly different processing flow between the flotation stages . As shown in Figure 4, the flotation concentrate remover 142 is subjected to cleaner flotation 132 along with the rougher flotation concentrate 136, rather than being recycled to the rougher flotation 130 as shown in Figure 3.
[0072] Reference is now made to Figure 5 to illustrate an example embodiment including size separation of a mineral material feed and separate flotation processing of different size fractions of mineral material. As shown in Figure 5, a first mineral material 102a is subjected to a first flotation processing 100a and a second mineral material 102b is subjected to a second flotation processing 100b. Either or both of the first flotation processing 100a and the second flotation processing 100b can be, for example, according to or including aspects of flotation processing 100 as shown and described in relation to any of Figures 1 to 4. O first mineral material 102a includes a first fraction from the size separation 152 of a mineral material feed 150. of the second mineral material 102b includes a second fraction from the size separation 152 of the mineral material feed 150. the material feed mineral 150 may be the result of previous comminution operations. The first fraction included in the mineral material 102a has a smaller particle size of average weight than the second fraction included in the second mineral material 102b. Processing as shown in Figure 5 provides significant flexibility to beneficially process fractions of different size for more optimal flotation processing of each fraction. Said processing also allows significant flexibility for post-flotation processing with oxidative treatment to prepare a flotation concentrate for leaching of precious metal.
[0073] Figure 6 shows the same processing as shown in Figure 5 including separation by size 152, first flotation processing 100a and second flotation processing 100b. However, in the processing of Figure 6, a first flotation concentrate 106a from the first flotation processing 100a and a second flotation concentrate 106b from the second flotation processing 100b are subjected to post-flotation processing 160. During processing post-flotation 160, at least a portion of the first flotation concentrate 106a and the second flotation concentrate 106b can be subjected to oxidative treatment to decompose sulfide minerals and expose the precious metal to allow for the recovery of improved leaching of precious metal.
[0074] Figures 7 and 8 show some example modalities for post-flotation processing 160 of Figure 6 in which the material from the first flotation concentrate 106a and the second flotation concentrate 106b can be processed together for oxidative treatment. As shown in Figure 7, post-flotation processing 160 may include filtration 170a of the first flotation concentrate 106a and separate filtration 170b of the second flotation concentrate 106b. Separate filtration of concentrates allows more optimized filtration techniques to be used for different particle sizes than different concentrates. As an alternative processing to that shown in Figure 7, the first flotation concentrate 106a and the second flotation concentrate 106b could be combined and submitted as a combined food for a single filtration step. As shown in Figure 7, the first filtered flotation concentrate 106a from the filtrate concentrate 170a is combined with the second filtered flotation concentrate 106b from the filtrate concentrate 170b to form a combined concentrate 172. The combined concentrate 172 is subjected to oxidative treatment 174 to decompose sulphide minerals and expose precious metal to make the precious metal more favorable for recovery by leaching. Residual solids 176 from oxidative treatment 174 can be further processed to recover gold, such as by leaching precious metal from residual solids 176 resulting from oxidative treatment 174.
[0075] In the alternative processing mode shown in Figure 8, post-flotation processing 160 may include subjecting the second flotation concentrate 106b to filtration 170 and may include no filtration of the first flotation concentrate 106a before combining the first flotation concentrate 106a with the second flotation concentrate 106b to prepare the combined concentrate 172. The first flotation concentrate 106a, comprised of smaller particles than the second flotation concentrate 106b, is more difficult to filter without complications, despite the combined concentrate 172 may have higher acidification requirements to an extent oxidative treatment 174 involving acid processing (eg, acid pressure oxidation, biooxidation).
[0076] The post-flotation processing 160 shown in Figure 6 may also involve separate oxidative treatment of the first flotation concentrate 106a and the second flotation concentrate 106b. Figures 9 and 10 show some example modalities for post-flotation processing 160 which can include separate oxidative treatments. As shown in Figure 9, post-flotation processing 160 includes subjecting the first flotation concentrate 106a to filtration 170a and the second flotation concentrate 106b to filtration 170b. After filtration 170a, the first flotation concentrate 106a is subjected to a first oxidative treatment 174a to decompose the sulphide minerals and to prepare a first solid residue 176a which is more favorable for the recovery of precious metal, such as by leaching. After filtration 170b, the second flotation concentrate 106b is subjected to a second oxidative treatment 174b to decompose sulphide minerals and to prepare a second residual solid residue 176b which is more favorable for the recovery of precious metal, such as by leaching. Figure 10 shows the same processing as shown in Figure 9 except that the second flotation concentrate 106b is subjected to filtration 170 and the first flotation concentrate 106a is not subjected to filtration. The first oxidative treatment 174a and the second oxidative treatment 174b can be of the same or different oxidative techniques. For example, the first oxidative treatment 174a can be an atmospheric oxidation process due to the small particle size of the first flotation concentrate 106a, whereas the second oxidative treatment 174b can be a pressure oxidation process due to the larger particle size. of the second flotation concentrate 106b.
[0077] Unless expressly stated otherwise, percentages and concentrations are on a weight basis, except that percentages and concentrations of gas composition are on a volume basis unless expressly stated otherwise.
[0078] The following examples further illustrate and describe various aspects, modalities and aspects with respect to the invention.
[0079] Example 1
[0080] Three different samples of sulfide ore materials that contain gold from the Carlin region of Nevada, USA that have various carbonate contents are tested. Table 1 summarizes the chemical analysis information for the samples. Table 2 provides a summary of information on mineralogical composition on the estimation of ore samples based on semi-quantitative X-ray diffraction (XRD) analysis. Table 3 summarizes information on mineralogical composition on the estimation of ore samples based on modal mineralogical analysis.
[0081] Table 1


[0082] Table 2

[0083] Table 3


[0084] Ore samples n ° 2 and n ° 3 contain significant carbonate content that consumes acid in the form of dolomite or dolomite and calcite, whereas Ore Sample n ° 1 does not contain a significant amount of carbonate minerals. The ore samples are subjected to flotation testing in the laboratory under various flotation conditions, with and without prior conditioning with a conditioning gas containing carbon dioxide. The different gas compositions used for flotation and / or conditioning in this and other tests in other examples provided below are summarized in Table 4.
[0085] Table 4

[0086] Each of the No. 1 through No. 3 samples is comminuted to a target P80 size of 105 microns (80% by weight of particles smaller than 105 microns). Before flotation, however after any conditioning with a conditioning gas, amyl potassium xanthate equivalent to 100 grams per ton of Ore Sample is added as a collector and AERO® MX6205 (Cytec) equivalent to 50 grams per ton of Ore Sample. is added as a promoter. The flotation in each ore sample is carried out at an acidic pH. For tests in which 100 percent air is used as the flotation gas (gas composition G1), the sludge is acidified before flotation with the addition of sulfuric acid to try to reach a target pH of 5.5 and acid Additional sulfuric is added as needed during flotation to try to keep the pH of the sludge around the target pH. For tests where the flotation gas contains carbon dioxide, no acid is added to the sludge before or during the flotation. Flotation is carried out in a laboratory flotation cell for about 16 minutes at a sludge density of about 25 percent solids. Some tests include conditioning with carbon dioxide (G6) gas before flotation. A summary of some tests and test results are presented in Tables 5, 6 and 7 for ore samples No. 1, No. 2 and No. 3, respectively.
[0087] Table 5


[0088] Table 6


[0089] Table 7


[0090] With respect to Table 5 summarizing the tests for Ore Sample No. 1, Tests 1-1 and 1-5 represent baseline air flotation tests with the addition of sulfuric acid for pH control , with test 1-5 using tap water instead of process water that is used in other tests. In tests 1-3 and 1-2 the gold recoveries slightly higher in the result of concentrate from the use of CO2 in the flotation gas with or without previous conditioning with CO2 gas. This modest recovery improvement is achieved without removing oxygen from the flotation gas. In test 1-7, the ore sample is comminuted in a nitrogen gas environment to help prevent oxidation of freshly exposed sulfide mineral grains. In relation to test 1-3, test 1-7 shows only a small improvement in the recovery of gold in the concentrate. A small additional improvement in the recovery of gold in the concentrate is seen for test 1-6 when the flotation gas is a mixture of only carbon dioxide and nitrogen gas. A significantly higher gold recovery, however, is shown by test 1-4 in which the ore sample is comminitive in a nitrogen gas environment and the sludge is conditioned with a mixture of carbon dioxide and nitrogen gas before flotation with a mixture of carbon dioxide and nitrogen gas.
[0091] Ore Samples n ° 2 and n ° 3 are ores much more difficult to process by flotation than Ore Samples n ° 1. They not only contain significant concentrations of acid-consuming carbonate that prevents pH control in a desired range of acidic pH by adding acid, as well as they contain higher concentrations of arsenic iron sulfides which are difficult to flotate. Flotation of nitrogen gas with pH control by adding sulfuric acid has been a state of the art technique for improved flotation of said ores.
[0092] With respect to the results summarized in Table 6 for Ore Sample No. 2, tests 2-1 and 2-5 represent baseline tests using air flotation and test 2-14 represents a comparison with flotation of nitrogen gas of the prior art, all of which include the conventional practice of adding sulfuric acid to try to reach a desired pH of acid sludge of 5.5, which is significantly complicated by acid reaction with that of carbonate minerals. As seen in Table 6, nitrogen gas flotation (test 2-14) achieves a significantly higher gold recovery in the concentrate than in baseline air flotation (tests 2-1 and 2-5). For comparison, test 2-9 flies the ore sample with air at a natural pH, with no pH control. As expected, gold recovery is better with nitrogen gas flotation than with baseline air flotation tests, and air flotation without the addition of sulfuric acid is lower than the baseline air flotation. base with the addition of sulfuric acid to reach an acidic pH for flotation.
[0093] Test 2-13 tests performance using nitrogen gas flotation but without the addition of sulfuric acid to decompose acid-consuming carbonates to reach an acidic pH for flotation, but instead of subjecting the sludge to gas conditioning CO2 before flotation. Surprisingly, gold recovery is almost as high as with the flotation of nitrogen gas from the state of the art test with the addition of sulfuric acid, but without the cost or complexity of high acid additions to decompose acid-consuming carbonates for achieve a desired acidic pH. Test 2-12 uses air flotation without the addition of sulfuric acid, but without the previous conditioning of CO2 gas. Although gold recovery for test 2-12 is not as high for test 2-13 using nitrogen gas for flotation, gold recovery is slightly higher than gold recovery in line air flotation tests. base with the addition of sulfuric acid. This is surprising, since gold recovery is maintained without the cost and complication of large additions of sulfuric acid to break down carbonates to try to control the pH of the sludge at a desired acid pH level during flotation.
[0094] A series of tests is carried out in different processing combinations without the addition of sulfuric acid and using flotation gas composed of a mixture of carbon dioxide and air (17:83). In test 2-3, flotation is performed without prior conditioning of CO2 gas and pH control during flotation is provided only by CO2 in the flotation gas. Notably, gold recovery in the concentrate is only slightly less than for baseline air flotation tests, but without the cost or complication of large additions of sulfuric acid. Test 2-8 uses the same conditions as test 2-3, except that the ore is communicated in a nitrogen gas environment to reduce the potential for newly exposed sulfide mineral grain surfaces to oxidize prior to flotation. This resulted in a gold recovery almost as high as the baseline nitrogen gas flotation in test 2-14. Surprisingly, this is achieved without requiring major additions of sulfuric acid and without removing oxygen from the flotation gas, as the flotation gas in test 2-8 includes 83% air, equaling up to about 17% air. oxygen gas in the flotation gas mixture.
[0095] Tests 2-10, 2-11, 2-2, 2-6 and 2-15 all include conditioning of CO2 gas for different lengths of time before flotation with the mixture of CO2 and air for flotation gas . Significant improvement in gold recovery in the concentrate is observed in connection with baseline air flotation tests for 5, 10 and 20 minutes of conditioning, with gold recoveries generally comparable to the test baseline nitrogen gas flotation. 2-14. This is surprising considering that the 215 test does not include the cost or complication of large additions of sulfuric acid or elimination of oxygen gas from the flotation gas.
[0096] Tests 2-7 and 2-4 use a mixture of carbon dioxide and nitrogen gas (17:83) as a flotation gas, with and without previous conditioning with CO2 gas, and without the addition of sulfuric acid . The pH control is provided only by carbon dioxide in the conditioning gas and / or flotation gas. As seen in a comparison of test 2-7 with test 2-3, use of this flotation gas mixture has a positive effect on gold recovery related to the use of a mixture of CO2 and air. The results for test 2-4 are particularly surprising, including conditioning with a mixture of CO2 and nitrogen gas prior to flotation with a mixture of CO2 and nitrogen gas, which shows significantly higher gold recovery in the concentrate than with conditions flotation of nitrogen gas of the state of the test technique 2-14.
[0097] With respect to the results summarized in Table 7 for Ore Sample No. 3, flotation with a mixture of CO2 and air (17:83) without prior conditioning (test 3-3) resulted in comparable gold recovery or slightly better than baseline air flotation conditions with the addition of sulfuric acid to break down acid-consuming carbonates and adjust the pH (tests 3-1 and 3-5). With binary use of the mixture of CO2 and air for flotation gas both with previous comminution in nitrogen gas (test 3-7), before conditioning of CO2 gas (test 3-2) and use of a mixture of CO2 and N2 (17:83) insofar as flotation gas without prior conditioning (test 3-6) results in significant improvement of gold recovery in the concentrate related to baseline air flotation tests, and without the cost or complexity large additions of sulfuric acid. Particularly surprising is the very high level of gold recovery achieved in the concentrate using a mixture of CO2 and N2 for the flotation gas with previous conditioning with a mixture of CO2 and nitrogen gas conditioning (test 3-4), again without the cost or complexity of large additions of sulfuric acid required to break down acid-consuming carbonates for flotation at a desired acidic pH.
[0098] Example 2
[0099] The samples are from sulfide ore materials that contain gold obtained from mud samples extracted from a conventional air flotation operation in Nevada, USA Tables 8-10 summarize the chemical analysis information for the samples ore samples, designated here as Ore Samples No. 4, No. 5 and No. 6. Tables 8-10 also show particle size distribution information and chemical analysis information for different particle size ranges. Table 11 summarizes the mineralogical composition information for the ore samples estimated by model mineralogy analysis. Mineral Sample # 4 is a top quality ore sample that has negligible carbonate content that is relatively favorable to conventional air flotation processing to prepare a gold-enriched sulfide concentrate. Ore Samples No. 5 and No. 6 are more difficult ores in which each contains carbonate that consumes significant acid, mostly present in the form of dolomite, and contains more arsenic iron sulfide content than Sample No. 4.
[00100] Table 8


[00101] Table 9


[00102] Table 10



[00103] Table 11


[00104] Each ore sample is subjected to cyclone separation to separate the ore sample into a smaller fraction of particle size (cyclone overflow) and a larger fraction of particle size (cyclone flow) for separate flotation test in different fractions. Flotation tests are also performed on whole ore samples for comparison. Tables 12-14 summarize the particle size information for the integral ore sample and the overflow and flow fractions separated from the cyclone separation. Flotation tests are carried out in a laboratory flotation cell in a slurry with a solids density generally about 30 to 35% by weight of solids for flow flotation tests and about 15 to 20% by weight of solids. solids for overflow flotation tests, with some tests including prior conditioning by spraying the sludge with a conditioning gas containing carbon dioxide. Flotation is carried out for about 16 minutes. The test results are summarized in Tables 15 to 20. In Tables 15 to 20, the cyclone flow fractions are designated as “U / F” and the cyclone overflow fractions are designated as “O / F”. The test also includes leaching of gold cyanide from flotation tails to assess the total amount of gold that is recoverable both in the flotation concentrate and through cyanide leaching from the flotation tails.
[00105] Table 12

[00106] Table 13


[00107] Table 14

[00108] Table 15


[00109] Table 16


[00110] Table 17



[00111] Table 18



[00112] Table 19



[00113] Table 20


[00114] Tables 15 and 16 summarize the test results for Ore Sample No. 4. Table 15 shows results for the separate test performed on flow and overflow fractions, designated as “U / F” and “O / F” in the tables. Table 16 shows combined results for corresponding overflow and flow test pairs compared to flotation tests performed on a whole ore sample. As shown in Table 15, for the Ore Sample No. 4 flow fractions, both gold recovery in concentrate and total gold recovery including tail leaching do not vary much between different test conditions. For overflow fractions, the recovery of gold in the concentrate is superior in tests using carbon dioxide in the flotation gas preceded by conditioning with a gas containing carbon dioxide (tests 4-72-2 and 4-72-1), however, the recovery of total gold from overflow samples including tail leaching is affected by a much smaller amount. As shown in Table 16, the separate flotation of overflow and flow fractions showed only a small increase in total gold recovery for the best tests performed related to the flotation of whole ore samples (tests 4-11 and 4-12) , and processing of integral ore with carbon dioxide (test 412) shows no increase in total gold recovery through conventional air flotation (test 4-11). Again, Ore Sample # 4 is a superior grade ore that is generally favorable for conventional air flotation and does not contain significant acid-consuming carbonate qualities.
[00115] With respect to Table 17 in relation to sample no. 5, the total gold recovery is significantly higher for the two overflow and flow fractions using carbon dioxide gas, with the best corresponding gold recoveries with tests including both conditioning and flotation with gas compositions including carbon dioxide. It is particularly worth noting the information summarized in Table 18. For the Full Ore Sample tests (5-11 and 5-12), total gold recovery is perfected by only a small amount using carbon dioxide gas (from 53.0% to 54.4%). However, combined gold recoveries from separate flotation of flow and overflow fractions using gas containing carbon dioxide during flotation and prior conditioning with a gas containing carbon dioxide result in much higher gold recoveries. (more than 11% points), with the combined test using a mixture of CO2 and N2 (17:83) providing the largest increase (more than 13% points).
[00116] Test results on Ore Sample No. 6 summarized in Table 19 show improvements in total gold recovery for some flow tests and for some overflow tests related to baseline air flotation, despite of not being as good as those experienced for Ore Sample # 5. As shown in Table 20, conditioning and flotation using carbon dioxide increased the total gold recovery by only a small amount in the Ore Sample tests (from 64.0% to 65.0%). However, total gold recoveries for Ore Sample # 6 increased significantly for combined results from separate flotation in overflow and runoff fractions. As for the results for Ore Sample # 5, these improved gold recoveries are achieved without the major issues of sulfuric acid additions and pH control resulting from the presence of significant amounts of acid-consuming carbonate.
[00117] Example 3
[00118] Ore Sample No. 2 in an aqueous slurry at about 25% by weight of solids density is conditioned for 20 minutes with conditioning gas of composition G6 (100% CO2) by spraying the conditioning gas in a sludge contained in a laboratory flotation cell. The mud samples are taken at different times and the mud liquid is analyzed for concentrations of different dissolved components. Table 21 summarizes the results of the solution analysis over time for a number of components. The calcium concentration increases moderately over time, which may be due at least in part to the cleaning of surface species that contain calcium from grains of sulfide mineral. Particularly noticeable is the large increase over time in dissolved iron, which increased by a factor of about 5, which may be due at least in part to the dissolution of species containing iron, such as iron hydroxides, from grains of sulphide mineral. Said cleaning of the sulphide mineral grains can be particularly beneficial for the effective flotation of sulphide minerals.
[00119] Table 21



[00120] Example 4
[00121] Samples with one kilogram of sulfide ore materials that contain gold (Ore Samples No. 7, No. 8, No. 9 and No. 10) are each comminuted up to a P80 size of approximately 140 microns and divided in a manner wet rotary in room divisions that are used as food for four different conditioning tests. The mineralogical composition information in the estimated sample from XRD analysis is summarized in Table 22. For testing, the sample divisions are used with both process water and tap water. The analyzes in the two different process waters and spout waters used in the tests are shown in Table 23. The conditioning tests use gas compositions G1, G2, G5 and G6 as conditioning gases. The rates of gas spraying during conditioning tests with the various gases are summarized in Table 24. For tests using 100% nitrogen gas (G2), before spraying gas, sulfuric acid is added to decompose carbonates and try to achieve a reduction in a sludge pH to a target pH of 5.5, and additional sulfuric acid is added periodically to try to maintain approximately that target pH. Following conditioning with the conditioning gas, each ore sample is subjected to flotation using the same gas composition for the flotation gas as used for the conditioning gas, except that tests using G6 as a conditioning gas are followed by flotation with a flotation gas of the G3 composition. The mud samples are taken periodically during conditioning and the mud liquid is analyzed for the concentration of selected dissolved components. Following the flotation, the flotation concentrates are analyzed by XRD in order to estimate the mineralogical composition information for the concentrates. After conditioning and before flotation, amyl potassium xanthate collector is added in a slurry equivalent to about 100 grams per ton of ore and AERO® MX6205 promoter is added in a slurry equivalent to about 50 grams per ton of ore . The tests on Ore Sample No. 8 are performed using process water and also using tap water.
[00122] Table 22

[00123] Table 23


[00124] Table 24

[00125] Tables 25-29 summarize the pH results as a function of time for tests on different ore samples. Figures 11-14 graphically summarize changes in concentrations of calcium, magnesium, iron and sulfur in a mud liquid as a function of time as a percentage related to the initial concentration at the start of the test. Tests using sulfuric acid and nitrogen gas uniformly show greater increases in the concentrations of dissolved calcium and magnesium, which may partially reflect the decomposition of carbonates with the addition of sulfuric acid. Concentrations of dissolved iron tend to increase significantly for tests using nitrogen, carbon dioxide or a mixture of carbon dioxide and nitrogen, which may indicate that conditions in all of those tests may be conducive to removing oxidized iron species, such as hydroxides iron, from surfaces of grains of sulfide mineral. Air tests uniformly show a reduction over time in dissolved iron concentrations, indicating that iron may be precipitating, which is generally a detrimental condition for effective sulfide mineral flotation. Regarding the sulfur in the solution, only tests using sulfuric acid and nitrogen gas show significant increases in concentration over time.
[00126] Table 25

[00127] * Addition of H2SO4 equal to 2,120 kg per ton of ore
[00128] Table 26

[00129] * Addition of H2SO4 equal to 21.032 kg per ton of ore
[00130] Table 27


[00131] * Addition of H2SO4 equal to 16.516 kg per ton of
[00132] Table 28


[00133] * Addition of H2SO4 equal to 32.168 kg per ton of ore
[00134] Table 29

[00135] * Addition of H2SO4 equal to 8,220 kg per ton of ore
[00136] Table 30 summarizes the mineral composition information in flotation concentrates estimated from XRD analysis for process water tests. Perceptibly, for tests using sulfuric acid and nitrogen gas on ore samples that contain high concentrations of calcite (Ore Samples No. 8 and No. 9), significant gypsum is identified in the concentrates, which may indicate precipitation of calcium sulfate during the test as a consequence of the addition of sulfuric acid and corresponding decomposition of a portion of the calcite. Also, Tables 25-29 provide the amounts of sulfuric acid added during nitrogen gas testing, expressed on a kilogram basis of sulfuric acid requirements per ton of ore. As seen in Tables 25-29, ore samples # 8 and # 9 that contain significant concentrations of calcite have much higher sulfuric acid requirements than ore samples # 7 and # 10 that contain lower levels of minerals of carbonate and only in the form of dolomite. The high sulfuric acid requirements for Ore Samples No. 8 and No. 9 coupled with significant levels of gypsum in the resulting concentrates may indicate that the calcite in those samples is very reactive when consuming sulfuric acid related to the sample content of samples. Ore No. 7 and No. 10.
[00137] Gypsum precipitation can present a significant processing problem in which the presence of very fine particles of gypsum precipitate can significantly complicate the filtration of the concentrate in preparation for further processing.
[00138] Table 30


[00139] The following discussion of the invention and different aspects of it was presented for purposes of illustration and description. The following is not intended to limit the invention to only the form or forms specifically disclosed herein. Consequently, variations and modifications commensurate with the above teachings, and the skill or knowledge of the relevant technique, are within the scope of the present invention. The modalities described above are still intended to explain the best known ways to practice the invention and to allow others with skill in the art to use the invention in such modalities, or in others, and with several modifications necessary for the particular applications or uses of the present invention. It is intended that the appended claims are interpreted to include alternative modalities up to the limit permitted by the prior art. Although the description of the invention included the description of one or more possible modalities and certain variations and modifications, other variations and modifications are within the scope of the invention, eg, as they may be within the skill and knowledge of those in the art after understanding the present revelation. It is intended to obtain rights that include alternative modalities to that permitted limit, including alternative, exchangeable and / or equivalent structures, functions, ranges or steps those claimed, whether or not alternative, interchangeable and / or equivalent structures, functions, ranges or steps are said to be disclosed here, and without intending to publicly dedicate any patentable matter. In addition, any aspect described or claimed with respect to any revealed variation may be combined with one or more of any other aspects of any other variation or variations, to the extent that the aspects are not necessarily technically compatible, and all such combinations are within the scope of the present invention. The description of an aspect or aspects in a particular combination does not exclude the inclusion of an additional aspect or aspects. The steps and sequencing of processing are for illustration purposes only, and these illustrations do not exclude the inclusion of other steps or other sequencing of steps. Additional steps can be included between illustrated processing steps or before or after any illustrated processing step.
[00140] The terms "that comprises", "containing", "including" and "that has", and grammatical variations of these terms, are intended to be inclusive and not limiting in the sense that the use of said terms indicates the presence of some conditions or aspects, but not excluding the presence of any other condition or aspect as well. The use of the terms "that comprises", "containing", "including" and "that has", and grammatical variations of those terms with respect to the presence of one or more components, subcomponents or materials, also include and are intended to reveal the most specific terms in which the term "that comprises", "containing", "including" or "that has" (or the variation of that term) as the case may be, is replaced by any of the more specific terms "that essentially consist of" or "Consisting of" or "consisting of only" (or the appropriate grammatical variation of said more specific terms). For example, a declaration that something "comprises" a declared element or elements is also intended to include and reveal the more specific narrow modalities of the thing "which essentially consists of the" declared element or elements, and the thing "consisting of the" declared element (s). Examples of the various aspects have been provided for purposes of illustration, and the terms "example", "for example" and the like indicate illustrative examples that are not limiting and should not be interpreted or understood as limiting an aspect or aspects to any particular example. The term "at least" followed by a number (eg, "at least one") means the number or more than that number. The term "at least a part from "means all or a part that is less than the whole. The term" at least a part "means all or a part that is less than the whole.

权利要求:
Claims (21)
[0001]
1. Method for processing mineral material containing precious metal with one or more sulphide minerals and containing non-sulphide gangue minerals comprising acid consuming carbonate, the method characterized by comprising a flotation process, in which the flotation process comprises: flotting the mineral material in an aqueous liquid medium at a pH less than pH 7 with flotation gas to prepare a flotation concentrate enriched in minerals associated with sulphide and associated precious metal as fed to the flotation and a decantate enriched in minerals non-sulfide gangue related to the mineral material as fed for flotation; and prior to flotation, conditioning the mineral material, which comprises treating a sludge including the mineral material with a conditioning gas comprising at least 5% by volume of carbon dioxide; and where: the mineral material comprises at least 1% by weight of acid consuming carbonate before and after conditioning; the conditioning comprises reducing the pH of the sludge from a pH above pH 7 to a pH range of 5 to pH 6.2 due mainly or entirely to the carbon dioxide in the conditioning gas; during conditioning and flotation no more than 10% acid-consuming carbonate, in the mineral material as fed for conditioning, is decomposed; flotation is carried out at a pH in the range of pH 5 to pH 6.2; and the mineral material comprises at least 1% by weight of acid consuming carbonate when the mineral material is fed for flotation and the decant and the flotation concentrate together comprise at least 1% by weight of carbonate which consumes acid relative to the combined weight decanted and flotation concentrate.
[0002]
Method according to claim 1, characterized in that the flotation gas comprises at least 5% by volume of carbon dioxide.
[0003]
Method according to claim 2, characterized in that the flotation gas is selected from the group consisting of a gaseous composition consisting essentially of carbon dioxide and gaseous nitrogen, a gaseous composition consisting essentially of a mixture of dioxide carbon and air, and a gaseous composition consisting essentially of carbon dioxide.
[0004]
Method according to claim 1, characterized in that the aqueous liquid medium comprises a combined concentration of dissolved calcium and magnesium of at least 500 milligrams per liter; and because no more than 10% of the acid-consuming carbonate, in the mineral material as fed for flotation, is decomposed during flotation.
[0005]
Method according to claim 1, characterized in that the method is essentially in the absence of pH adjustment through the addition of acid during or before flotation.
[0006]
6. Method according to claim 4, characterized in that: the mineral material, as fed for flotation, comprises at least 0.2 parts per million by weight of gold and the flotation concentrate is enriched in gold relative to the mineral material , as fed to flotation; and the flotation is a mass sulfide flotation.
[0007]
Method according to claim 1, characterized in that the conditioning gas comprises at least 10% by volume of carbon dioxide.
[0008]
Method according to claim 1, characterized in that the conditioning gas comprises at least 25% by volume of carbon dioxide.
[0009]
Method according to claim 1, characterized in that the conditioning gas comprises no more than 5% by volume of gaseous oxygen.
[0010]
Method according to claim 1, characterized in that it comprises conditioning and in which: the mineral material comprises at least 2% by weight of acid consuming carbonate before and after conditioning and when the mineral material is fed for flotation ; and the decantate and the flotation concentrate together comprise at least 2% by weight of carbonate which consumes acid relative to the combined weight of the decantate and the flotation concentrate.
[0011]
Method according to claim 1, characterized in that: the mineral material, as fed for flotation, comprises at least 0.5% by weight of sulfur sulfide and at least 3.5% by weight of carbonate minerals selected from the group consisting of dolomite, calcite, magnesite and combinations thereof; and the mineral material, as fed to the flotation, comprises at least 1% by weight of iron-containing sulfide minerals and that the flotation concentrate is enriched in the iron-containing sulfide minerals related to the mineral material as fed to the flotation.
[0012]
12. Method according to claim 1, characterized in that the mineral material, as fed for flotation, comprises at least 0.5% by weight of sulphide minerals selected from the group consisting of arsenopyrite, arsenic pyrite, pyrrhotite arsenic, arsenic marcaite and combinations thereof and the flotation concentrate being enriched in sulfide minerals from the group related to the mineral material as fed to the flotation; and the compliant mineral material, fed for flotation, comprises at least 500 parts per million by weight of arsenic and for the flotation concentrate to be enriched in arsenic related to the mineral material as fed for flotation.
[0013]
Method according to claim 1, characterized in that the conditioning gas is a gas mixture comprising at least 98% by volume of a combination of carbon dioxide and nitrogen gas.
[0014]
Method according to claim 1, characterized in that the flotation gas is a gas mixture comprising at least 98% by volume of a combination of carbon dioxide and nitrogen gas.
[0015]
Method according to claim 1, characterized in that the conditioning gas and the flotation gas each comprise at least 98% by volume of a combination of carbon dioxide and nitrogen gas.
[0016]
16. Method according to claim 1, characterized in that the flotation gas consists essentially of carbon dioxide and nitrogen gas.
[0017]
17. Method according to claim 1, characterized in that the conditioning gas consists essentially of carbon dioxide and nitrogen gas.
[0018]
18. Method according to claim 1, characterized in that the conditioning gas consists essentially of carbon dioxide.
[0019]
19. Method according to claim 1, characterized in that the flotation process is a first flotation process, by the flotation being a first flotation, by the mineral material being a first mineral material, by the flotation gas being a first flotation gas, by the flotation concentrate being a first flotation concentrate and by the decanting being a first decanting, and by the method comprising: separating by size a mineral material fed in at least two fractions, a first said fraction having a particle size of smaller average weight a second said fraction having a larger average weight particle size; wherein the mineral material fed comprises precious metal with one or more sulfide minerals and non-sulfide gangue including acid consuming carbonate in an amount of at least 1% by weight related to the weight of the mineral material fed; and wherein each of said first fraction and said second fraction includes a portion of the precious metal from the mineral material fed and a portion of the carbonate that consumes acid from the mineral material fed; wherein the first mineral material includes at least a portion of the first said fraction; second flotation which processes a second mineral material including at least a portion of the second said fraction, the second flotation process which comprises the second flotation in aqueous liquid medium at a pH less than pH 7 with a second flotation gas to prepare a second flotation concentrate enriched in sulphide minerals and associated precious metal related to the second mineral material, as fed for the second flotation, and a second decantate enriched in non-sulfide denim minerals related to the second mineral material as fed for the second flotation.
[0020]
20. Method according to claim 19, characterized in that the conditioning is the first conditioning and the second flotation process comprises a second conditioning of the second mineral material, the second conditioning comprising treating a sludge that includes the second mineral material with a second gas conditioning system comprising at least 5% by volume of carbon dioxide.
[0021]
21. Method according to claim 19, characterized in that it comprises a post-flotation process of the first flotation concentrate and the second flotation concentrate, which comprises oxidative treatment of the first flotation concentrate and the second flotation concentrate to decompose sulphide minerals and exposing precious metal, in which the post-flotation process further comprises: first oxidative treatment of the first flotation concentrate; and second oxidative treatment of the second flotation concentrate separated from the first oxidative treatment; and the second oxidative treatment is an alkaline pressure oxidation.

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同族专利:

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公开号 | 公开日

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AU2014260247A1|2015-11-12|

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CA2911147A1|2014-11-06|

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WO2014179134A1|2014-11-06|

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US9545636B2|2017-01-17|

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AU2014260247B2|2017-08-03|

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PE20160021A1|2016-01-21|

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US20160074872A1|2016-03-17|

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法律状态:
2018-02-27| B06F| Objections, documents and/or translations needed after an examination request according art. 34 industrial property law|

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2019-11-05| B06U| Preliminary requirement: requests with searches performed by other patent offices: suspension of the patent application procedure|

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2020-08-18| B06A| Notification to applicant to reply to the report for non-patentability or inadequacy of the application according art. 36 industrial patent law|

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2020-12-01| B09A| Decision: intention to grant|

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2021-02-09| B16A| Patent or certificate of addition of invention granted|Free format text: PRAZO DE VALIDADE: 20 (VINTE) ANOS CONTADOS A PARTIR DE 23/04/2014, OBSERVADAS AS CONDICOES LEGAIS. |

优先权:

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申请号 | 申请日 | 专利标题

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US201361817781P| true| 2013-04-30|2013-04-30|

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US61/817,781|2013-04-30|

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PCT/US2014/035188|WO2014179134A1|2013-04-30|2014-04-23|Method for processing mineral material containing acid-consuming carbonate and precious metal in sulfide minerals|

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