WO2021157417A1 - クロム合金の製造方法 - Google Patents

クロム合金の製造方法 Download PDF

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Publication number
WO2021157417A1
WO2021157417A1 PCT/JP2021/002540 JP2021002540W WO2021157417A1 WO 2021157417 A1 WO2021157417 A1 WO 2021157417A1 JP 2021002540 W JP2021002540 W JP 2021002540W WO 2021157417 A1 WO2021157417 A1 WO 2021157417A1
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WIPO (PCT)
Prior art keywords
slag
mass
chromium
less
producing
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PCT/JP2021/002540
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English (en)
French (fr)
Japanese (ja)
Inventor
博一 杉森
太一 小畑
西村　博文
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Ｊｆｅマテリアル株式会社
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Priority to JP2021575737A priority Critical patent/JPWO2021157417A1/ja
Publication of WO2021157417A1 publication Critical patent/WO2021157417A1/ja

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    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22B—PRODUCTION AND REFINING OF METALS; PRETREATMENT OF RAW MATERIALS
    • C22B5/00—General methods of reducing to metals
    • C22B5/02—Dry methods smelting of sulfides or formation of mattes
    • C22B5/04—Dry methods smelting of sulfides or formation of mattes by aluminium, other metals or silicon
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C1/00—Making non-ferrous alloys
    • C22C1/02—Making non-ferrous alloys by melting
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C27/00—Alloys based on rhenium or a refractory metal not mentioned in groups C22C14/00 or C22C16/00
    • C22C27/06—Alloys based on chromium
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
    • C22C38/30—Ferrous alloys, e.g. steel alloys containing chromium with cobalt

Definitions

  • the present invention relates to a method for producing a chromium alloy containing chromium and iron, and to a method for producing a chromium alloy having few impurities.
  • Low carbon ferrochrome is known as a chromium alloy containing chromium and iron.
  • Low-carbon ferrochrome is generally produced by a method of reducing chromium ore with a silicon-based reducing agent (see Patent Document 1).
  • the so-called Peran method is adopted.
  • the basic steps of the Peran method are the first step of dissolving chromium ore and fresh lime, and the dissolving raw material (hereinafter referred to as primary slag) dissolved in the first step is stirred by adding a reducing agent to carry out a reduction reaction.
  • a second step of producing low carbon ferrochrome and secondary slag is provided. Stirring in the second step is usually performed by relay drilling in which two ladle are prepared and the molten metal of the primary slag containing the silicon-based reducing agent is repeatedly transferred.
  • the applicant has proposed a method for producing metallic chromium having extremely low impurities (see Patent Document 2).
  • This metallic chromium contains 99% by mass or more of chromium.
  • the method for producing metallic chromium is the first step of dissolving chromium oxide, raw lime, and a reducing agent and causing a reduction reaction to produce a chromium-containing metal and primary slag, and a chromium-containing separated primary slag. It comprises a second step of adding slag and fluorite to the metal to smelt the chromium-containing metal.
  • this method for producing metallic chromium since the produced chromium-containing metal is refined in the second step, impurities contained in the metallic chromium of the product can be extremely reduced.
  • the starting material is not chromium ore, but chromium oxide obtained by roasting chromium ore with soda and extracting with sulfuric acid, so that there is a problem that the cost of the starting material is high. be.
  • Some uses of chromium alloys do not require as high a chromium content as metallic chromium, but allow a small amount of iron to be included.
  • the present invention has been made in view of the above problems, and an object of the present invention is to provide a method for producing a chromium alloy using chromium ore as a starting material and having extremely few impurities.
  • one aspect of the present invention is to use a first step of dissolving chromium ore and fresh lime in a primary slag and a dissolved raw material (hereinafter referred to as primary slag) dissolved in the first step. 20% by mass or more and 70% by mass or less of the theoretical reduction amount for reducing chromium oxide and iron oxide is added and stirred in the second step of producing secondary slag and by-product metal, and from the by-product metal.
  • This is a method for producing a chrome alloy, which comprises a third step of adding a reducing agent to the separated secondary slag and stirring the slag to form a chrome alloy with the tertiary slag.
  • a chromium alloy having extremely few impurities such as P, S, and Co can be produced by using chromium ore as a starting material.
  • FIG. 1 is a process diagram of a method for producing a chromium alloy according to an embodiment of the present invention.
  • first step (S1) a mixture of chromium ore and quicklime as a medium solvent is dissolved in an electric furnace to produce a dissolved raw material (hereinafter referred to as primary slag) (first step (S1)).
  • the reason why the hot water pool is formed is that a stable amount of heat is maintained even when the primary slag is discharged.
  • the primary slag is discharged from the outlet to the reaction vessel.
  • the hot water temperature of the primary slag is as high as 1800 ° C. or higher and 2000 ° C. or lower.
  • a reducing agent is added to the reaction vessel from which the primary slag has been discharged and stirred to produce the secondary slag and the by-product metal (second step (S2)).
  • the reducing agent is a silicon-based reducing agent such as silicochrome, ferrochrome, and metallic chromium.
  • the amount of the reducing agent is adjusted to 20% by mass or more and 70% by mass or less, preferably 40% by mass or more and 50% by mass or less, of the theoretical reduction amount for reducing chromium oxide and iron oxide of the primary slag according to the following formula. .. Cr 2 O 3 + 3/2Si ⁇ 2Cr + 3/2SiO 2 FeO + 1 / 2Si ⁇ Fe + 1 / 2SiO 2
  • FIG. 2 shows the standard free energy of oxide formation. As shown in FIG. 2, Cu and Co have a lower oxygen affinity than Cr and Fe. Therefore, Cu, Co, etc. are preferentially reduced and transferred to by-product metals. Therefore, impurities such as Cu and Co in the secondary slag can be reduced.
  • the oxygen affinity of Fe is lower than that of Cr. Therefore, when chromium oxide and iron oxide are weakly reduced, Fe is preferentially reduced and transferred to a by-product metal. Therefore, the Cr / Fe of the secondary slag can be increased.
  • the amount of the reducing agent is less than 20% by mass of the theoretical reduction amount, it becomes difficult to transfer impurities such as Cu and Co to the by-product metal.
  • the amount of the reducing agent exceeds 70% by mass of the theoretical reduction amount, the chromium oxide of the secondary slag is reduced and the Cr / Fe of the secondary slag becomes small.
  • the basicity of the secondary slag is adjusted to 1.5 or more and 3.5 or less.
  • FIG. 3 shows the relationship between the basicity of the secondary slag and (P) / (Cr) of the secondary slag. As shown in FIG. 3, when the basicity is lowered, (P) / (Cr) can be lowered, that is, P of the secondary slag can be reduced. On the other hand, as the basicity decreases, the S of the secondary slag increases. In order to reduce both P and S, the basicity is adjusted to 1.5 or more and 3.5 or less, preferably 1.5 or more and 3 or less. The basicity can be adjusted by the amount of quicklime charged into the electric furnace, or by the silica stone added to the reaction vessel.
  • the second step is performed in a reaction vessel equipped with a gas bottom blowing device.
  • a gas bottom blowing device By using the gas bottom blowing device, sufficient stirring is possible to transfer impurities to the by-product metal, and it is possible to prevent the temperature of the molten metal from dropping.
  • the temperature of the molten metal (secondary slag) after the reaction is completed is a high temperature of 1800 ° C. or higher and 2000 ° C. or lower.
  • the temperature of the secondary slag is raised, the S of the secondary slag volatilizes and the S as an impurity becomes smaller. If the temperature of the molten metal in the second step is less than 1800 ° C., the molten metal may solidify in the subsequent third and fourth steps, and casting may not be possible.
  • FIG. 4 shows a vertical cross-sectional view of the reaction vessel.
  • a refractory 4 is provided on the bottom of the iron skin 3 of the reaction vessel 1.
  • a slit type plug 2 as a gas bottom blowing device is inserted into the through hole in the center of the refractory material 4.
  • the secondary slag is poured into another reaction vessel having a gas bottom blowing device, and the recovered silicochrome as a reducing agent is added to the reaction vessel and stirred (third step (S3)).
  • the third step chromium oxide and iron oxide of the secondary slag react with the recovered silicochrome to form a tertiary slag and a chromium alloy.
  • the recovered silicochrome is silicochrome recovered in the third step described later.
  • impurities such as P, S, Cu and Co in the secondary slag are extremely small.
  • a chromium alloy with a small amount of impurities can be produced.
  • recovered silicochrome having a small amount of C as a reducing agent, a chromium alloy having a small amount of C as an impurity can be produced.
  • the molten chrome alloy is cast into a mold to become a product.
  • the chromium alloy of the product contains Cr in an amount of 80% by mass or more and 95% by mass or less, and Fe in an amount of 5% by mass or more and 20% by mass or less. Further, P of the chromium alloy is 0.007% by mass or less, S is 0.003% by mass or less, C is 0.01% by mass or less, and Co is 0.01% by mass or less. Further, since Al is not used as the reducing agent, Al is 0.01% by mass or less.
  • the reaction vessel used in the third step is a reaction vessel having the same gas bottom blowing device as the reaction vessel used in the second step. Since the reaction vessel used in the third step has substantially the same structure as the reaction vessel used in the second step, the same reference numerals are given and the description thereof will be omitted.
  • the gas bottom blowing device in the third step sufficient stirring is possible to transfer chromium and iron to the metal, and it is possible to prevent the temperature of the molten metal from dropping. Since the reduction reaction between chromium oxide and iron oxide is an exothermic reaction, the temperature of the molten metal (tertiary slag) after the reaction is completed is a high temperature of 1800 ° C. or higher and 2000 ° C. or lower.
  • the produced tertiary slag is separated from the chromium alloy, hot water is discharged into a ladle, metallic silicon is added as a silicon-based reducing agent, and the mixture is stirred (fourth step (S4)).
  • the chromium oxide remaining in the tertiary slag reacts with the metallic silicon to produce the quaternary slag and silicochrome.
  • the silicochrome is separated and recovered from the quaternary slag, and the recovered silicochrome is used as the main reducing agent in the third step.
  • FIG. 5 shows the relationship between [Si]% and [C]% of recovered silicochrome.
  • the silicon content decreases as the silicon content increases.
  • the carbon content can be reduced.
  • the recovered silicon chromium having a small amount of carbon as a main reducing agent in the third step, a chromium alloy having a small amount of carbon as an impurity can be produced.
  • the reducing agent used in the third step is only recovered silicochrome.
  • another reducing agent metal silicon
  • the mass of recovered silicochrome is at least 1/2 of the total mass of the reducing agent.
  • the quaternary slag separated from the recovered silicochrome is used for roadbed material or fertilizer.
  • the chromium content of the quaternary slag is adjusted to 1.0% by mass or less, and the basicity is adjusted to 1.3 or less, preferably 1.2 or less.
  • Silica stone may be placed in the ladle to adjust the basicity.
  • FIG. 6 is a graph showing the relationship between (Cr)% of quaternary slag and [Si]% of recovered silicochrome. As shown in FIG. 6, if the silicon content of the recovered silicon chromium is 30% by mass or more, the chromium content of the quaternary slag can be 1.0% by mass or less.
  • the harmful hexavalent chromium compound of the quaternary slag can be changed to a harmless trivalent chromium compound.
  • the following hexavalent chromium compounds that bind to CaO as in equation from (CaO ⁇ CrO 3) CaO is deprived, because harmful hexavalent chromium compound is changed to harmless trivalent chromium compound (Cr 2 O 3) .. 2 (CaO ⁇ CrO 3 ) + 2SiO 2 ⁇ 2 (CaO ⁇ SiO 2 ) + Cr 2 O 3 + 3 / 2O 2
  • a chromium alloy was manufactured according to the manufacturing process diagram of FIG. As raw materials, 7700 kg of chromium ore and 4000 kg of quicklime were charged into an electric furnace and melted to produce primary slag.
  • the primary slag was poured into a reaction vessel, 1080 kg of silicochrome (40% by mass of the theoretical reduction amount) was added to the primary slag, and the mixture was stirred to produce 8440 kg of secondary slag and 1610 kg of by-product metal.
  • Table 1 shows the composition of the secondary slag.
  • the basicity of the secondary slag was 2.75.
  • the Cr / Fe ratio of the secondary slag was 10 or more, and the P, Co, and S of the secondary slag were extremely small.
  • Table 2 shows the composition of the by-product metal. P, Co, and S were present as by-products.
  • Table 3 shows the composition of the chromium alloy. Since the secondary slag with few impurities is reduced with recovered silicochrome, it is a chromium alloy having extremely few Al, P, Co, C and S.
  • Table 4 shows the composition of the tertiary slag.
  • Table 5 shows the composition of recovered silicochrome.
  • the carbon content of silicochrome was 0.001% by mass.
  • Table 6 shows the composition of the quaternary slag.
  • the content of Cr 2 O 3 in the quaternary slag was 0.5% by mass, and the basicity was 1.0. No harmful hexavalent chromium was detected in the quaternary slag.

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  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Materials Engineering (AREA)
  • Mechanical Engineering (AREA)
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  • Manufacturing & Machinery (AREA)
  • Manufacture And Refinement Of Metals (AREA)
  • Processing Of Solid Wastes (AREA)
PCT/JP2021/002540 2020-02-04 2021-01-26 クロム合金の製造方法 WO2021157417A1 (ja)

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Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH0551690A (ja) * 1991-08-26 1993-03-02 Nkk Corp 低炭素フエロクロムの製造方法
JP2002256323A (ja) * 2001-02-27 2002-09-11 Nippon Steel Corp ステンレス溶鋼の粗脱炭スラグの改質方法
JP2002543276A (ja) * 1999-04-22 2002-12-17 ホルシム リミティド 製鋼スラグを処理する方法
JP2003049235A (ja) * 2000-03-07 2003-02-21 Nkk Corp クロム含有金属及びその製造方法
JP2011094210A (ja) * 2009-10-30 2011-05-12 Jfe Material Co Ltd シリコクロムの脱炭素方法

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH0551690A (ja) * 1991-08-26 1993-03-02 Nkk Corp 低炭素フエロクロムの製造方法
JP2002543276A (ja) * 1999-04-22 2002-12-17 ホルシム リミティド 製鋼スラグを処理する方法
JP2003049235A (ja) * 2000-03-07 2003-02-21 Nkk Corp クロム含有金属及びその製造方法
JP2002256323A (ja) * 2001-02-27 2002-09-11 Nippon Steel Corp ステンレス溶鋼の粗脱炭スラグの改質方法
JP2011094210A (ja) * 2009-10-30 2011-05-12 Jfe Material Co Ltd シリコクロムの脱炭素方法

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