• 专利附录
  • 专利说明
  • 权利要求
  • 类似技术
  • 同族专利
  • 引用文献
  • 法律状态
  • 优先权
    • 专利摘要:
    METHOD OF DECONTAMINATION; CHROME CAST IRON, containing carbon 1.5-8%, chromium 10-30% and at least one of the additional elements - silicon (not more than 4%), nickel (not more than 20%), cobalt, manganese, molybdenum (in total not more than 20%), including the supply of a jet of oxygen vertically to the surface of the cast iron through an oxygen supersonic tuyere i characterized in that, in order to accelerate decarburization and improve the chromium-free solution without adding reducing elements or compositions, the moment of supplying the jet of oxygen to the surface cast iron with supersonic Cd speed is determined by the inequality Cd 1740 IJ3 - the initial temperature where the pig iron, s, § Cj, is the initial carbon content in the cast iron, Z, the tuyere is set at a height of 5-30 diameters of the critical section of the nozzle, the specific oxygen consumption is 2.5O e 3 per 1 ton of liquid iron with a relative pressure of oxygen of 8-12 bar, while when the carbon content in the melt is 1.5-2.5 times lower than the initial QD, its content in the iron and at a temperature above decarburization is carried out by direct exposure to the buried page and oxygen to a non-sprinkled gas-liquid pigment emulsion to obtain a cohesive carbon content in the melt of 0.3%. INVENTIONS 1Wf «« il.vV.KJ.ff,
    公开号:SU1170974A3
    申请号:SU813229959
    申请日:1981-01-19
    公开日:1985-07-30
    发明作者:Маризи Жорж
    申请人:Южин Асьер (Фирма)；
    IPC主号:
    专利说明:

    The invention relates to metallurgy, namely to decarburization of chromium or chromium-nickel cast irons containing 1.5-8% by weight of carbon, 10-30% by weight of Cr, up to 30% by weight. Ni and, in the known cases of the additive, Co, Mn and Mo.
    Numerous methods are known, which allow the decarburization of cast iron under the action of oxygen, alone or in a mixture with another gases, at atmospheric pressure or under reduced pressure. The oxygen or gas mixture may be brought into contact with the liquid metal, for example, by blowing through the base of the converter or, alternatively, may be injected onto the metal surface.
    D1 and 21.
    In particular, in the LD method, the decarburized cast iron is processed in a vertical converter with a pit located above the level of the liquid iron. Through this lance a stream of oxygen enters, which is directed to the surface of the liquid metal melt.
    Studies carried out in this way provide a better understanding of the effect of the jet of oxygen on the metal solution and on the slag that covers it.
    In case of dephosphorization of the decarburization of cast iron using the LD method applied to a 200 T converter, the reaction between oxygen and the liquid metal occurs mainly due to the presence of droplets of the liquid metal in the tank. The flow of liquid metal thrown by droplets through the slag depends on the force of collision of the jet of oxygen with the liquid metal. This supply of metal can reach and even exceed a ton per second. Under this condition, an emulsion forms between the liquid metal, the donkey and the gas mixture, the volume of which depends not only on the force of the collision of the oxygen jet, but also on the flow characteristics of the pshak. In case of a weak collision force, it is mainly phosphores that is removed, on the contrary, with a large collision force, carbon is preferentially removed.
    The analysis showed that the conditions favorable for dephosphorization, the P content in droplets is 100 times less than the P content
    in a metal bath. The increase in the collision rate of the oxygen jet with the metal bath favors the decarburization reaction, as it entails an increase in the number of droplets dropped. The very fast decarburization that occurs in this case is accelerated by the cracking of metal droplets, which is obtained from the formation of CO bubbles.
    In the process of decarburizing iron by the LD jet of oxygen, the ultrasonic at the exit of the nozzle, by its collision, creates an emulsion between the liquid metal and slag and a very significant gas phase containing variable amounts of oxygen and carbon oxides. The volume of the emulsion is highly dependent on the viscosity of the slag. Slags rich in FeO, very fluid, give rise to the formation of emulsions, the volume of which reaches 3-4 times the volume of the liquid metal by the end of blowing. Inside the emulsion, the decarburization of liquid metal droplets causes two competing processes: oxidation of carbon with oxygen contained in the gas phase and oxidation of carbon with FeO contained in the slag.
    This method, developed first for the decarburization of conventional iron, was used to process chromium iron.
    The closest to the proposed technical essence and the achieved result is the method of decarburization of chromium cast iron containing 1.5-8-8% carbon, 10-30% chromium and at least one of the additional elements silicon (not more than 4%), nickel (not more than 20%), cobalt, manganese, molybdenum (in the amount of not more than 20%), including the supply of a jet of oxygen vertically to the surface of cast iron through an oxygen lance with a supersonic speed DJ.
    Synthetic cast iron with Cr, obtained by mixing ordinary cast iron and carbon-containing ferrochrome, containing approximately 4% carbon and approximately 15-16% chromium, is decarburized by blowing oxygen to the final content with 0.05%. At the end of the decarburization, the temperature exceeds 1900 s, V
    In this way, the amounts of oxides of Cr and Fe, which are transferred to the slag, are formed mainly at the beginning of blowing. When the concentration of these oxides in the donkey becomes sufficiently high, they react, in turn, with the carbon contained in the metal bath, and the formed CO is released. A portion of the chromium oxide formed at the beginning of the reaction is carried away by hot gases, in the form of dust. The other part remains in the tank and can be recovered and recovered during the subsequent recovery operation.
    Consequently, the method includes stages and necessitates a relatively expensive secondary treatment of the spike in order to recover part of the chromium oxide of chromium, which is carried away by hot gases, can be recovered with difficulty. In addition, in this process, slag rich in Cr oxide is necessary to ensure decarburization. This slag reduces the effectiveness of the collision of the oxygen jet with the metal bath and, therefore, slows down the teasing of the latter. It follows from this that decarburization is slowed down and, on the contrary, the loss of Cr by oxidation increases.
    The purpose of the invention is to accelerate decarburization and improve the yield of chromium without the addition of reducing elements or compositions.
    This goal is achieved by the fact that, according to the decarburization method of chrome iron MONfeHT, the supply of an oxygen jet to the iron surface at a supersonic speed of iron is determined by the inequality
    Tjj +65 C 1740
    where Tjj is the initial temperature
    cast iron,
    Cjj - the initial carbon content in cast iron,%
    The tuyere is installed at a height of 530 diameters of the critical section of the nozzle; the specific oxygen consumption is maintained at 2.5-3 ha 1 ton of liquid iron at a relative oxygen pressure of 8-12 bar.
    at the same time, when the content of carbon in the melt is 1.5-2.5 times less than its initial content in the iron and at a temperature above decarburization lead; direct influence of the buried oxygen stream on the slag-free emulsion gas - liquid iron to obtain the final carbon content in the melt is less than 3%.
    The proposed method is carried out in an oxygen converter, the lining of which is made of high-temperature resistant chromo-magnesite type bricks.
    The decarburization is carried out by supplying high-pressure oxygen with the aid of a tuyere which is introduced into the converter from above through its throat. The oxygen jet is directed vertically downwards and the distance between the end of the nozzle and the surface of the liquid metal varies from 5 to 30 times the diameter of the critical section of the nozzle. The specific consumption of oxygen per ton of liquid iron should be approximately 3 nm / min, at a pressure that varies from 8 to 12 rel. bar.
    Under these conditions, the first phase of the reaction is carried out, during which the slag layer is gradually expelled from the surface of the bath with a stream of gas. At the same time, the oxidation of the most oxidizable elements contained in cast iron occurs. During this period, chromium is oxidized, mainly. At the same time, the temperature of the metal quickly rises. In the second phase, chromium, oxidized in the initial stage, is reduced by carbon, which is still present in the metal bath. During this period of chromium oxide reduction, the temperature continues to rise. Higher than the tempoature, approximately 17001800 C, the third phase of the reaction begins, during which the boiling caused by the reaction of oxygen with the carbon of the bath does not occur very much on the surface, but also even in the volume of the bath of iron. In this case, an emulsion forms between the gas phase and the liquid metal, the level of which gradually increases and which begins to surround the nozzle.
    Inside this emulsion, oxygen is in direct contact with liquid. metal with almost no slag. Under these conditions, the process of extremely fast direct decarburization of the metal takes place without the intermediate formation of chromium oxide. The gas / metal emulsion, which is formed and the level of which rises above the initial surface of the metal bath, plays the role of a filter that retains solid particles of chromium, iron or other metal oxides that can form in certain cases. Due to the constant contacting of a portion of the bulk metal volume, which can exceed 25%, with the gas phase, the decarburization efficiency increases over a wide range. For the same reason, there is a faster increase in the temperature of the liquid metal. It has been found that chromium cast iron can be decarburized by this method very quickly and at a constant speed. Finally, a gas / metal emulsion plays the role of a heat insulator and very significantly reduces heat loss.
    Experience has shown that it is possible to continuously maintain the gas / metal emulsion during this third phase of the reaction, continuing the decarburization very quickly and at a constant rate for a final carbon content close to 0.2%. The analyzes carried out at this time showed that the yield of Cr in the solution in the metal bath was at least 97% by weight: the Cr contained. in the cast iron entered first in the converter. This result is obtained without the addition of one or more reducing elements or reducing agents such as silicon or others. It is possible to further reduce this carbon content, elongation of oxygen blowing, but starting from this moment, secondary oxidation of chromium and diffusion of carbon, which limits the reaction kinetics, are achieved. In this case, if it is required to further reduce the carbon content, they prefer to start the converter under reduced pressure, for example, by covering it with a sealed vault, including a pipeline to remove gases, connected to pumps capable of reducing the pressure in the converter to a level of about ten Torr or slightly less. , with the possibility of additional introduction of oxygen and / or neutral gas.
    In many cases, the amount of oxygen present in the cast iron and in the residual slag is sufficient to acidify the residual carbon and easily reach the final carbon content below 0.03%. Under these conditions, the overall yield of chromium c is about 98%. This result is obtained without adding one or. several reducing elements or reducing compounds.
    P ROME er. Cast iron having the following composition is processed,%: Cr 17, C 6, SiO O, Mi 0.3, S 0.03 P 0.03.
    Up to 1430 С 60 kg of this cast iron in the furnace, which induces heating. The surface of the iron cast iron is covered with approximately 0.5 kg of lime. Then, blowing up oxygen using a vertical nozzle with a flow rate of 168 ml / min at a pressure of 9 rel. bar. The diameter of the critical section of the nozzle is 2 and the vertical distance between the end of the nozzle and the bath is 30 minutes. Blowing in this way, oxygen reacts with the bath and three successive phases of the reaction can be observed.
    In the first phase, the oxygen reacts mainly with the surface of the iron bath, an oxide predominantly, in Cr, Sin Fe. To the extent that formed by the oxide, which contain most of the; accumulate on the surface of the bath, the secondary reaction of the reduction of these oxides with carbon begins. The speed of this reduction reaction increases gradually along with increasing the tag-sherature to approximately 1650 ° C in the 10th minute. The formed CO is released during this time and burns, giving a flame.
    In the second phase, starting from the 11th minute, the reduction of oxides, mainly chromium oxide; carbon becomes faster than the formation of these oxides. During this period of brisk reaction, the temperature still rises, but less quickly. Starting from about the 15th minute, the decarburization rate stabilizes: the carbon content, which in this case is about 4%, continues to decrease at a rate of almost 0.3% per minute and at the same time, a corresponding reduction of chromium oxide is observed. This mechanism lasts up to the 20th minute, the bath temperature in this case reaches approximately 1750s, while the C content decreases to approximately 2.9%. By the end of this second phase, the initially formed metallic oxides are almost completely reduced.
    At the 20th minute, conditions are created for the start of the third phase, which reduces the carbon content to below 0.3%, and to almost 0.2%. At the beginning of this third phase, the bath temperature of the cast iron increases rapidly. Under these conditions, while maintaining the oxygen consumption condition and the distance between the end of the nozzle and the cast iron bath, the formation of an emulsion between the gas and the cast iron, which quickly covers the bath surface, is observed, then thickened to twice the size of the initial cast iron. Everything happens as if the iron itself, under the action of a jet of oxygen and the formation of CO, directly reacting oxygen with carbon contained in this iron, boils in its entire mass due to the existing physicochemical conditions. Within the resulting emulsion, the reaction rates decrease, allowing The decarburization is carried out at a high rate to a final carbon content of approximately 0.2%, which is reached by the 29th minute. In this case, the temperature is about 1860 ° C and the oxygen blowing is stopped. The analyzes carried out at this stage show that the yield of Cr is 97.5% by weight.
    The final decarburization is then carried out in a known manner using vacuum in an oven at
    assisting pumps to achieve a residual pressure of approximately 2 Torr in the 20th minute. During this operation, the carbon content is reduced to 0.02% only due to the oxygen present in the molten iron and the residual pshaka. As a result of this experiment, it was found that the yield of chromium is 98%.
    In view of the small amount of chu gong used in this experiment, it is necessary to compensate for too large heat losses. For this, additional induction is maintained throughout the operation.
    heating with constant power to better compensate for heat loss. Such additional heating is only necessary on a small scale of experience. Obviously, on an industrial scale, this heating will be redundant.
    Among the conditions that contribute to the formation of an emulsion between
    gas phase and hot chromium iron, it has been established that in order to be able to start the formation of a gas / metal emulsion, it is important that the initial temperature of the metal
    baths satisfied yes inequality
    Tj, -t-65 Cj,
    1740
    where Tjj is the initial temperature of chromium iron, at the moment of starting to blow oxygen, С, Ср is the initial carbon content in the iron, wt.% :.
    If the carbon content in chromic iron is 6%, the temperature of the latter should be above 1,740–390–1350 s at the moment oxygen begins to blow. Experience has shown that
    the higher the actual temperature in relation to a certain critical value, the sooner favorable conditions appear for the formation of an emulsion between the gas
    phase and liquid metal during
    decarburization process. This means that the duration of the first two phases of the decarburization process, during which the
    removal of carbon, primarily by reducing the formation of metal oxides, will be reduced in favor of the third phase of direct decarburization
    you liquid iron due to the formation of a gas / metal emulsion. The proposed method can be applied not only to chromium chugna without other large additives, but also to chromium containing additives of other metals, such as Ni, Co, Mn or Mo. Consequently, this method can be directly obtained from chromium or chromium-nickel iron, in which the corresponding additives are made, stainless ferritic steels, n, oluferritic steels, austenitic steels or austenitic-ferrite steels.
    7097410.
    Experience has shown that one of the important factors that ensure the durability of the nozzle for injecting oxygen inside the converter is
    5, a protective layer that forms on the surface of this nozzle during operation. This nozzle, predominantly of copper, is cooled by circulating water and its surface is covered with a layer of very refractory oxides .. This layer plays a dual role as an insulator and protects the nozzle against the hazards of the prorgox and investigator 15 but water loss.
    权利要求:
    Claims (1)
    [1]
    'METHOD OF CARBON-FREE CARBON; CHROME IRON containing carbon 1.5-8%, chromium 10-30% and at least one of the additional elements - silicon (not more than 4%), nickel (not more than 20%), cobalt, manganese, molybdenum (in total no more than 20%), including the supply of a stream of oxygen vertically to the surface of cast iron through an oxygen lance with
    I supersonic speed, characterized in that, in order to accelerate decarburization and improve chrome suitable for chromium without adding reducing elements or compositions, the moment of supply of a jet of oxygen to the surface of cast iron with a supersonic speed is determined by the inequality
    Т р + 65 С о > 1740 g where Т о is the initial temperature of cast iron, ° C, Op is the initial carbon content in cast iron,%, The lance is set at a height
    5-30 diameters of the nozzle critical section, specific oxygen consumption is maintained equal to 2.53 nm * / min per 1 ton of molten iron at a relative oxygen pressure of 8-12 bar, while achieving a carbon content in the melt of 1.5-2.5 times smaller its initial content of iron and at a temperature over 1700 C e decarburization are recessed direct influence on the oxygen jet bezshlakovuyu emulsion gas - liquid iron to give a final carbon content in the melt more gently 0.3%.
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    同族专利:
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    ES498749A0|1981-11-01|
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    CA1154967A|1983-10-11|
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    EP0033289B1|1984-11-28|
    AT10508T|1984-12-15|
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    引用文献:
    公开号 | 申请日 | 公开日 | 申请人 | 专利标题
    FR1309507A|1960-11-18|1962-11-16|Union Carbide Corp|Process for decarburizing steels with high chromium content|
    FR1407182A|1963-06-25|1965-07-30|Allegheny Ludlum Steel|Improvements to corrosion-resistant steel fabrication processes|
    US3575696A|1968-09-19|1971-04-20|Jones & Laughlin Steel Corp|Process for controlling the manufacture of high-chromium steels|
    US3507642A|1969-06-02|1970-04-21|Allegheny Ludlum Steel|Process for producing corrosion resistant steel|
    US3793002A|1971-10-14|1974-02-19|Siderurgie Fse Inst Rech|Method of introducing a combustible auxiliary liquid into blast furnace and a tuyere for carrying out the method|
    BE778449A|1971-02-16|1972-05-16|Krupp Ag Huettenwerke|PROCESS FOR THE ACCELERATION OF METALLURGIC REACTIONS AND DEVICE FOR IMPLEMENTING THE PROCESS|
    FR2267376B1|1974-04-11|1977-06-24|Creusot Loire|
    DE2651922C3|1976-11-13|1979-06-21|Stahlwerke Peine-Salzgitter Ag, 3150 Peine|Method for controlling the fresh process when refining pig iron|JPS59145717A|1983-02-04|1984-08-21|Ugine Aciers|Oxygen jetting nozzle for jetting stable supersonic speed stream for decarbonizing cast iron, particularly chrome castiron|
    FR2489368A1|1980-08-26|1982-03-05|Ugine Aciers|NEW NOZZLE FOR OXYGEN INJECTION LAUNCHER FOR DECARBURATION OF FONTES AND APPLICATION TO DECARBURATION OF CHROMIUM WAFERS|
    FR2540519A2|1980-08-26|1984-08-10|Ugine Aciers|Nozzle for injecting oxygen in a stabilised supersonic jet for decarburisation of molten metals, and, in particular, molten chromium|
    US5474737A|1993-07-01|1995-12-12|The United States Of America As Represented By The Secretary Of Commerce|Alloys for cryogenic service|
    JP3167888B2|1995-07-27|2001-05-21|川崎製鉄株式会社|Decarburization refining method of chromium-containing molten steel and upper blowing lance for refining gas|
    WO2010107859A2|2009-03-19|2010-09-23|Massachusetts Institute Of Technology|Method of refining the grain structure of alloys|
    法律状态:
    优先权:
    申请号 | 申请日 | 专利标题
    FR8001809A|FR2474531B1|1980-01-24|1980-01-24|PROCESS FOR DECARBURIZING CHROME FOUNDS FOR THE PREPARATION OF STAINLESS STEELS BY JET OF SUPERSONIC OXYGEN|
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