WO2024154734A1 - 亜鉛回収方法及びジンクフェライト分解方法 - Google Patents

亜鉛回収方法及びジンクフェライト分解方法 Download PDF

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WO2024154734A1
WO2024154734A1 PCT/JP2024/000978 JP2024000978W WO2024154734A1 WO 2024154734 A1 WO2024154734 A1 WO 2024154734A1 JP 2024000978 W JP2024000978 W JP 2024000978W WO 2024154734 A1 WO2024154734 A1 WO 2024154734A1
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Prior art keywords
zinc
solution
raw material
aqueous solution
aqueous
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English (en)
French (fr)
Japanese (ja)
Inventor
和彦 元場
宏行 松浦
憲治 拝生
咲子 朝長
芳恵 玉井
修司 母里
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KINOTECH Corp
University of Tokyo NUC
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KINOTECH Corp
University of Tokyo NUC
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Priority to EP24744655.2A priority Critical patent/EP4653559A1/en
Priority to JP2024571768A priority patent/JPWO2024154734A1/ja
Priority to CN202480006659.XA priority patent/CN120457224A/zh
Priority to KR1020257026969A priority patent/KR20250150545A/ko
Publication of WO2024154734A1 publication Critical patent/WO2024154734A1/ja
Anticipated expiration legal-status Critical
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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
    • C22B19/00—Obtaining zinc or zinc oxide
    • C22B19/34—Obtaining zinc oxide
    • 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
    • C22B1/00—Preliminary treatment of ores or scrap
    • C22B1/005—Preliminary treatment of scrap
    • 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
    • C22B19/00—Obtaining zinc or zinc oxide
    • C22B19/20—Obtaining zinc otherwise than by distilling
    • 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
    • C22B19/00—Obtaining zinc or zinc oxide
    • C22B19/20—Obtaining zinc otherwise than by distilling
    • C22B19/24—Obtaining zinc otherwise than by distilling with leaching with alkaline solutions, e.g. ammonia
    • 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
    • C22B19/00—Obtaining zinc or zinc oxide
    • C22B19/20—Obtaining zinc otherwise than by distilling
    • C22B19/26—Refining solutions containing zinc values, e.g. obtained by leaching zinc ores
    • 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
    • C22B19/00—Obtaining zinc or zinc oxide
    • C22B19/30—Obtaining zinc or zinc oxide from metallic residues or scraps
    • 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
    • C22B3/00—Extraction of metal compounds from ores or concentrates by wet processes
    • C22B3/04—Extraction of metal compounds from ores or concentrates by wet processes by leaching
    • C22B3/06—Extraction of metal compounds from ores or concentrates by wet processes by leaching in inorganic acid solutions, e.g. with acids generated in situ; in inorganic salt solutions other than ammonium salt solutions
    • C22B3/10—Hydrochloric acid, other halogenated acids or salts thereof
    • 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
    • C22B3/00—Extraction of metal compounds from ores or concentrates by wet processes
    • C22B3/04—Extraction of metal compounds from ores or concentrates by wet processes by leaching
    • C22B3/12—Extraction of metal compounds from ores or concentrates by wet processes by leaching in inorganic alkaline solutions
    • 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
    • C22B7/00—Working up raw materials other than ores, e.g. scrap, to produce non-ferrous metals and compounds thereof; Methods of a general interest or applied to the winning of more than two metals
    • C22B7/005—Separation by a physical processing technique only, e.g. by mechanical breaking
    • 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
    • C22B7/00—Working up raw materials other than ores, e.g. scrap, to produce non-ferrous metals and compounds thereof; Methods of a general interest or applied to the winning of more than two metals
    • C22B7/006—Wet processes
    • C22B7/007—Wet processes by acid leaching
    • 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
    • C22B7/00—Working up raw materials other than ores, e.g. scrap, to produce non-ferrous metals and compounds thereof; Methods of a general interest or applied to the winning of more than two metals
    • C22B7/02—Working-up flue dust
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
    • Y02P10/00—Technologies related to metal processing
    • Y02P10/20—Recycling

Definitions

  • the present invention relates to a zinc recovery method and a zinc ferrite decomposition method, and in particular to a zinc recovery method and a zinc ferrite decomposition method for decomposing zinc ferrite, a difficult-to-dissolve substance contained in zinc-containing dust such as electric furnace dust generated during the melting and smelting of scrap in the electric furnace process, which is one of the iron-making processes, as well as primary or secondary dust such as blast furnace dust, blast furnace/converter dust, or RHF (Rotary Hearth Furnace) dust, and zinc-containing dust such as zinc ore burnt from zinc concentrate.
  • zinc-containing dust such as electric furnace dust generated during the melting and smelting of scrap in the electric furnace process, which is one of the iron-making processes, as well as primary or secondary dust such as blast furnace dust, blast furnace/converter dust, or RHF (Rotary Hearth Furnace) dust
  • zinc-containing dust such as zinc ore burnt from zinc concentrate.
  • electric furnace dust is generated as industrial waste containing zinc oxide and accounts for approximately 1.5% to 2.0% of the steel produced during the melting and smelting of scrap. It is said that 8 million tons of electric furnace dust are generated worldwide, and 400,000 tons are generated in Japan.
  • Patent Document 1 discloses a method for producing zinc, which includes a zinc-containing aqueous solution production process 102 in which an aqueous alkali hydroxide solution is used as an extraction solvent to selectively extract the zinc component in raw materials such as electric furnace dust, an electrolysis process 103 in which electrolysis is carried out using the zinc-containing aqueous solution as the electrolyte to produce zinc, and a chlorine concentration adjustment process 101 prior to the electrolysis process 103 in which the chlorine component contained in raw materials such as electric furnace dust is separated to reduce the chlorine concentration of the zinc-containing aqueous solution.
  • Patent Document 1 includes a zinc-containing aqueous solution generating step 102 using an aqueous alkali hydroxide solution as an extraction solvent for selectively extracting zinc components in raw materials such as electric furnace dust.
  • aqueous alkali hydroxide solution as an extraction solvent for selectively extracting zinc components in raw materials such as electric furnace dust.
  • ZnFe2O4 zinc ferrite
  • the present invention was made after the above-mentioned studies, and aims to provide a zinc recovery method capable of recovering zinc contained in zinc-containing dust and the like while reliably decomposing zinc ferrite contained in zinc-containing dust and the like, while suppressing the amount of energy consumed for heating and thereby suppressing increases in costs and environmental load, and a zinc ferrite decomposition method for decomposing such zinc ferrite.
  • the inventors conducted further research into decomposing zinc ferrite by contacting it with an aqueous alkali hydroxide solution such as an aqueous sodium hydroxide solution, and discovered that zinc ferrite decomposes at high temperatures and high concentrations, such as at a temperature of 150°C or higher, which is accompanied by an increase in boiling point, and in which the concentration of the alkaline agent such as sodium hydroxide in the aqueous alkali hydroxide solution is 70% by weight or more.
  • the inventor further investigated this phenomenon and found that in order to ensure the decomposition of zinc ferrite, it is important to maintain such a high-temperature, high-concentration state for a certain period of time.
  • the water in the aqueous alkali hydroxide solution evaporates quickly, and the water evaporates and dries up before the decomposition reaction is completed, resulting in a situation in which the decomposition reaction of zinc ferrite does not proceed at all.
  • the reaction vessel containing the zinc ferrite and the aqueous alkali hydroxide solution is sealed to form a closed system, and the evaporation of the water is suppressed, thereby maintaining such a high-temperature, high-concentration state until the decomposition reaction is completed, and thus the present invention was completed.
  • the zinc recovery method includes a contacting step of contacting a raw material containing zinc components and zinc ferrite or a treated raw material obtained by treating the raw material with an aqueous alkali hydroxide solution, a heating and temperature increasing step of heating the raw material or the treated raw material and the aqueous alkali hydroxide solution that have been contacted with each other in the contacting step to a temperature that reaches the boiling point of water exhibiting a boiling point rise, and a concentration maintaining step of maintaining the concentration of the alkaline agent contained in the aqueous alkali hydroxide solution when evaporation of water in the aqueous alkali hydroxide solution stops after the temperature reaches the boiling point, and the concentration is maintained in the concentration maintaining step.
  • the method includes a high-temperature high-alkali treatment step in which the zinc ferrite is decomposed into zinc oxide and iron oxide components by contacting the alkaline agent, the alkaline agent having a maintained temperature, with the zinc ferrite in the raw material or the treated raw material; a first leaching step in which the alkaline agent, the zinc oxide and the iron oxide are contacted with water at a temperature below the boiling point to dissolve the zinc oxide in the aqueous alkali hydroxide solution to obtain a first aqueous zinc-containing solution containing a zinc component, and a difficult-to-dissolve matter containing an iron oxide component that is not dissolved in the aqueous alkali hydroxide solution is obtained, and the difficult-to-dissolve matter is separated from the first aqueous zinc-containing solution; and a zinc recovery step in which the zinc component derived from the first aqueous zinc-containing solution is recovered.
  • the present invention provides a second aspect in which the alkaline agent is sodium hydroxide or potassium hydroxide, and in the high-temperature high-alkali treatment process, at least one of hydrogen peroxide and sodium nitrate is added as an oxidizing agent to the alkaline hydroxide aqueous solution, or at least one of sodium sulfite, sodium thiosulfate, sodium dithionite, hydrazine, and zinc metal is added as a reducing agent.
  • the alkaline agent is sodium hydroxide or potassium hydroxide
  • at least one of hydrogen peroxide and sodium nitrate is added as an oxidizing agent to the alkaline hydroxide aqueous solution, or at least one of sodium sulfite, sodium thiosulfate, sodium dithionite, hydrazine, and zinc metal is added as a reducing agent.
  • the present invention has a third aspect in which the alkaline agent is sodium hydroxide, and further includes a halogen washing step in which, prior to the high-temperature high-alkali treatment step, the raw material is washed with an aqueous sodium hydroxide solution having a pH value in the range of 8.5 to 10.5 to wash away halogen components contained in the raw material.
  • the alkaline agent is sodium hydroxide
  • a halogen washing step in which, prior to the high-temperature high-alkali treatment step, the raw material is washed with an aqueous sodium hydroxide solution having a pH value in the range of 8.5 to 10.5 to wash away halogen components contained in the raw material.
  • the present invention has a fourth aspect that further includes a purification step of contacting the first zinc-containing aqueous solution with metallic zinc to reduce and precipitate metal impurity components in the first zinc-containing aqueous solution that are more noble than zinc, thereby purifying the first zinc-containing aqueous solution.
  • the present invention provides a fifth aspect in which the zinc recovery process includes an electrolysis step in which electrolysis is performed using the first zinc-containing aqueous solution or a purified version of the first zinc-containing aqueous solution as an electrolyte to obtain electrolytically generated zinc and an electrolysis tail solution, and the electrolysis tail solution is sent to the high-temperature, high-alkali treatment step in a state in which the aqueous alkali hydroxide solution and zinc components remain, and the aqueous alkali hydroxide solution in the electrolysis tail solution is brought into contact with the raw material or the treated raw material.
  • the present invention provides a sixth aspect in which the zinc recovery step includes a zinc carbonate separation step in which the zinc component in the first zinc-containing aqueous solution or the purified first zinc-containing aqueous solution is separated as zinc carbonate and a residual liquid from which the zinc carbonate has been separated is obtained, and the residual liquid is sent to the high-temperature, high-alkali treatment step in a state in which the aqueous alkali hydroxide solution and the zinc component remain, and the aqueous alkali hydroxide solution in the residual liquid is brought into contact with the raw material or the treated raw material.
  • the present invention further includes a second leaching step in which, prior to the high-temperature, high-alkali treatment step, the raw material or the treated raw material is contacted with an aqueous sodium hydroxide solution, and the zinc component contained in the raw material or the treated raw material is dissolved in the aqueous sodium hydroxide solution and selectively extracted to obtain a second zinc-containing aqueous solution containing the zinc component, and a difficult-to-dissolve material containing zinc ferrite that is not dissolved in the aqueous sodium hydroxide solution is obtained, and the difficult-to-dissolve material containing zinc ferrite is sent to the high-temperature, high-alkali treatment step as the treated raw material and decomposed into a zinc oxide component and an iron oxide component, and in the first leaching step, the zinc oxide component is dissolved in the aqueous sodium hydroxide solution to obtain a fourth zinc-containing aqueous solution containing the zinc component.
  • a second leaching step in which, prior to the
  • the present invention provides an eighth aspect in which the fourth zinc-containing aqueous solution is sent to the second leaching process, where the zinc components contained in the fourth zinc-containing aqueous solution are selectively extracted and become part of the second zinc-containing aqueous solution.
  • the present invention also includes a ninth aspect in which the alkaline agent is sodium hydroxide, and a halogen washing step is further provided in which, prior to the second leaching step, the raw material is washed with an aqueous sodium hydroxide solution having a pH value in the range of 8.5 to 10.5 to wash out halogen components contained in the raw material, thereby obtaining a treated raw material.
  • the alkaline agent is sodium hydroxide
  • a halogen washing step is further provided in which, prior to the second leaching step, the raw material is washed with an aqueous sodium hydroxide solution having a pH value in the range of 8.5 to 10.5 to wash out halogen components contained in the raw material, thereby obtaining a treated raw material.
  • the present invention further comprises a purification step of contacting the second zinc-containing aqueous solution with metallic zinc to reduce and precipitate metal impurity components in the second zinc-containing aqueous solution that are more noble than zinc, thereby purifying the second zinc-containing aqueous solution.
  • the present invention provides an eleventh aspect in which the zinc recovery process includes an electrolysis process in which electrolysis is performed using the second zinc-containing aqueous solution or the purified second zinc-containing aqueous solution as an electrolyte to obtain electrolytically generated zinc and an electrolysis tail solution, and the electrolysis tail solution is sent to the high-temperature high-alkali treatment process in a state in which the aqueous alkali hydroxide solution and zinc components remain, and the aqueous alkali hydroxide solution in the electrolysis tail solution is brought into contact with the raw material or the treated raw material.
  • the present invention provides a twelfth aspect in which the zinc recovery step includes a zinc carbonate separation step in which the zinc component in the second zinc-containing aqueous solution or the purified second zinc-containing aqueous solution is separated as zinc carbonate and a residual liquid from which the zinc carbonate has been separated is obtained, and the residual liquid is sent to the high-temperature, high-alkali treatment step in a state in which the aqueous alkali hydroxide solution and the zinc component remain, and the aqueous alkali hydroxide solution in the residual liquid is brought into contact with the raw material or the treated raw material.
  • the zinc recovery step includes a zinc carbonate separation step in which the zinc component in the second zinc-containing aqueous solution or the purified second zinc-containing aqueous solution is separated as zinc carbonate and a residual liquid from which the zinc carbonate has been separated is obtained, and the residual liquid is sent to the high-temperature, high-alkali treatment step in a state in which the aqueous alkali hydro
  • the present invention further includes a magnetic separation process in which, prior to the high-temperature, high-alkali treatment process, a magnetic force is applied to the raw material or the treated raw material via a magnet, and a first mineral concentrate consisting of components attached to the magnet and a second mineral concentrate not attached to the magnet are separated according to the magnetic strength of the components in the raw material or the treated raw material; and a third leaching process in which the second mineral concentrate is sent to dissolve the zinc component contained in the second mineral concentrate in an aqueous sodium hydroxide solution to selectively extract the zinc component and obtain a third zinc-containing aqueous solution containing the zinc component, obtain a poorly soluble matter that is not dissolved in the aqueous alkali hydroxide solution, and separate the poorly soluble matter from the third zinc-containing aqueous solution.
  • the first mineral concentrate is sent to the high-temperature, high-alkali treatment process as the treated raw material, and the zinc ferrite in the first mineral concentrate is decomposed into the zinc
  • the present invention further includes, as a fourteenth aspect, a halogen washing step in which the alkaline agent is sodium hydroxide, and the raw material is washed with an aqueous sodium hydroxide solution having a pH value in the range of 8.5 to 10.5 prior to the third leaching step, to wash out halogen components contained in the raw material and obtain a treated raw material.
  • a halogen washing step in which the alkaline agent is sodium hydroxide, and the raw material is washed with an aqueous sodium hydroxide solution having a pH value in the range of 8.5 to 10.5 prior to the third leaching step, to wash out halogen components contained in the raw material and obtain a treated raw material.
  • the present invention further comprises a purification step of contacting the third zinc-containing aqueous solution with metallic zinc to reduce and precipitate metal impurity components in the third zinc-containing aqueous solution that are more noble than zinc, thereby purifying the third zinc-containing aqueous solution.
  • the present invention provides a sixteenth aspect in which the zinc recovery process includes an electrolysis process in which electrolysis is performed using the third zinc-containing aqueous solution or a purified version of the third zinc-containing aqueous solution as an electrolyte to obtain electrolytically generated zinc and an electrolysis tail solution, and the electrolysis tail solution is sent to the high-temperature, high-alkali treatment process in a state in which the aqueous alkali hydroxide solution and zinc components remain, and the aqueous alkali hydroxide solution in the electrolysis tail solution is brought into contact with the raw material or the treated raw material.
  • the present invention provides a seventeenth aspect in which the zinc recovery step includes a zinc carbonate separation step in which the zinc component in the third zinc-containing aqueous solution or the purified third zinc-containing aqueous solution is separated as zinc carbonate and a residual liquid from which the zinc carbonate has been separated is obtained, and the residual liquid is sent to the high-temperature, high-alkali treatment step in a state in which the aqueous alkali hydroxide solution and the zinc component remain, and the aqueous alkali hydroxide solution in the residual liquid is brought into contact with the raw material or the treated raw material.
  • the zinc recovery step includes a zinc carbonate separation step in which the zinc component in the third zinc-containing aqueous solution or the purified third zinc-containing aqueous solution is separated as zinc carbonate and a residual liquid from which the zinc carbonate has been separated is obtained, and the residual liquid is sent to the high-temperature, high-alkali treatment step in a state in which the aqueous alkali hydroxide solution
  • the zinc ferrite decomposition method of the eighteenth aspect of the present invention includes a contacting step of contacting a zinc ferrite-containing material containing zinc ferrite with an aqueous alkali hydroxide solution, a heating step of heating the zinc ferrite-containing material and the aqueous alkali hydroxide solution that have been contacted with each other in the contacting step to raise the temperature of the zinc ferrite-containing material and the aqueous alkali hydroxide solution to a temperature that reaches the boiling point of water that exhibits a boiling point rise, and a concentration maintaining step of maintaining the concentration of the alkaline agent contained in the aqueous alkali hydroxide solution when evaporation of water in the aqueous alkali hydroxide solution stops after the temperature reaches the boiling point, and the zinc ferrite in the zinc ferrite-containing material comes into contact with the alkaline agent whose concentration is maintained in the concentration maintaining step, thereby decomposing the zinc ferrite into zinc oxide components and
  • the zinc recovery method includes a contacting step of contacting a raw material containing zinc components and zinc ferrite or a treated raw material obtained by treating a raw material with an aqueous alkali hydroxide solution, a heating step of heating the raw material or the treated raw material and the aqueous alkali hydroxide solution that have been contacted with each other in the contacting step to raise the temperature of the raw material or the treated raw material and the aqueous alkali hydroxide solution to a temperature that reaches the boiling point of water that exhibits a boiling point rise, and a concentration maintaining step of maintaining the concentration of the alkaline agent contained in the aqueous alkali hydroxide solution when evaporation of water in the aqueous alkali hydroxide solution stops after the temperature reaches the boiling point, and the alkaline agent whose concentration is maintained in the concentration maintaining step comes into contact with the zinc ferrite in the raw material or the treated raw material, thereby producing zinc ferrite.
  • the method includes a high-temperature high-alkali treatment step in which zinc ferrite is decomposed into zinc oxide and iron oxide components, a first leaching step in which water is brought into contact with an alkaline agent, zinc oxide and iron oxide components at a temperature below the boiling point to dissolve the zinc oxide component in the alkaline hydroxide aqueous solution to obtain a first zinc-containing aqueous solution containing a zinc component, and a difficult-to-dissolve substance containing an iron oxide component that is not dissolved in the alkaline hydroxide aqueous solution is obtained, and the difficult-to-dissolve substance and the first zinc-containing aqueous solution are separated, and a zinc recovery step in which the zinc component derived from the first zinc-containing aqueous solution is recovered.
  • the alkaline agent is sodium hydroxide or potassium hydroxide
  • at least one of hydrogen peroxide and sodium nitrate as an oxidizing agent, or at least one of sodium sulfite, sodium thiosulfate, sodium dithionite, hydrazine and zinc metal as a reducing agent is added to the alkaline hydroxide aqueous solution, so that zinc ferrite contained in zinc-containing dust, etc. can be decomposed more reliably.
  • the alkaline agent is sodium hydroxide
  • the method further includes a halogen washing step in which the raw material is washed with an aqueous sodium hydroxide solution having a pH value in the range of 8.5 to 10.5 prior to the high-temperature high-alkali treatment step to wash away halogen components contained in the raw material, so that halogen components contained in zinc-containing dust, etc. can be reliably dissolved and washed away.
  • the zinc recovery method according to the fourth aspect of the present invention further includes a purification step in which metallic zinc is brought into contact with the first zinc-containing aqueous solution to reduce and precipitate metal impurity components that are more noble than zinc in the first zinc-containing aqueous solution, thereby purifying the first zinc-containing aqueous solution, thereby making it possible to recover zinc with reduced amounts of impurities.
  • the zinc recovery process includes an electrolysis step in which electrolysis is performed using the first zinc-containing aqueous solution or a purified first zinc-containing aqueous solution as the electrolyte to obtain electrolytically generated zinc and electrolytic tail solution, and the electrolytic tail solution is sent to the high-temperature, high-alkali treatment step in a state in which the alkaline hydroxide aqueous solution and zinc components remain, and the alkaline hydroxide aqueous solution in the electrolytic tail solution is brought into contact with the raw material or the treated raw material, so that electrolytically generated zinc with reduced impurity contamination can be stably recovered with good yield.
  • the zinc recovery step includes a zinc carbonate separation step in which the zinc components in the first zinc-containing aqueous solution or the purified first zinc-containing aqueous solution are separated as zinc carbonate, and a residual liquid from which the zinc carbonate has been separated is obtained, and the residual liquid is sent to the high-temperature, high-alkali treatment step in a state in which the aqueous alkali hydroxide solution and the zinc components remain, and the aqueous alkali hydroxide solution in the residual liquid is brought into contact with the raw material or the treated raw material, so that zinc carbonate with reduced impurity contamination can be recovered stably with good yield.
  • the method further includes a second leaching step in which, prior to the high-temperature high-alkali treatment step, the raw material or the treated raw material is contacted with an aqueous sodium hydroxide solution, and the zinc component contained in the raw material or the treated raw material is dissolved in the aqueous sodium hydroxide solution and selectively extracted to obtain a second zinc-containing aqueous solution containing the zinc component, and a difficult-to-dissolve material containing zinc ferrite that is not dissolved in the aqueous sodium hydroxide solution is obtained, and the difficult-to-dissolve material containing zinc ferrite is sent to the high-temperature high-alkali treatment step as the treated raw material and decomposed into zinc oxide components and iron oxide components, and in the first leaching step, the zinc oxide component is dissolved in the aqueous sodium hydroxide solution to obtain a fourth zinc-containing aqueous solution containing the zinc component. Therefore, in the high-temperature high-alkali treatment step, the raw material or
  • the fourth zinc-containing aqueous solution is sent to the second leaching step, where the zinc components contained in the fourth zinc-containing aqueous solution are selectively extracted and become part of the second zinc-containing aqueous solution, so that the zinc contained in the zinc-containing dust, etc. can be recovered more efficiently.
  • the alkaline agent is sodium hydroxide
  • the method further includes a halogen washing step in which, prior to the second leaching step, the raw material is washed with an aqueous sodium hydroxide solution having a pH value in the range of 8.5 to 10.5 to wash away the halogen components contained in the raw material and obtain a treated raw material, so that the halogen components contained in the zinc-containing dust, etc. can be reliably eluted and washed away.
  • the method further includes a purification step in which metallic zinc is brought into contact with the second zinc-containing aqueous solution to reduce and precipitate metal impurity components that are more noble than zinc in the second zinc-containing aqueous solution, thereby purifying the second zinc-containing aqueous solution, thereby making it possible to recover zinc with reduced amounts of impurities.
  • the zinc recovery step includes an electrolysis step in which electrolysis is performed using the second zinc-containing aqueous solution or a purified second zinc-containing aqueous solution as the electrolyte to obtain electrolytically generated zinc and electrolytic tail solution, and the electrolytic tail solution is sent to the high-temperature, high-alkali treatment step in a state in which the alkaline hydroxide aqueous solution and zinc components remain, and the alkaline hydroxide aqueous solution in the electrolytic tail solution is brought into contact with the raw material or the treated raw material, so that electrolytically generated zinc with reduced impurity contamination can be stably recovered with good yield.
  • the zinc recovery step includes a zinc carbonate separation step in which the zinc components in the second zinc-containing aqueous solution or the purified second zinc-containing aqueous solution are separated as zinc carbonate, and a residual liquid from which zinc carbonate has been separated is obtained, and the residual liquid is sent to the high-temperature, high-alkali treatment step in a state in which the aqueous alkali hydroxide solution and the zinc components remain, and the aqueous alkali hydroxide solution in the residual liquid is brought into contact with the raw material or the treated raw material, so that zinc carbonate with reduced impurity contamination can be stably recovered with good yield.
  • the method further includes a magnetic separation step in which, prior to the high-temperature high-alkali treatment step, a magnetic force is applied to the raw material or the treated raw material via a magnet, and a first mineral concentrate consisting of components attached to the magnet and a second mineral concentrate not attached to the magnet are separated according to the magnetic strength of the components in the raw material or the treated raw material, and a third leaching step in which the second mineral concentrate is sent to dissolve the zinc components contained in the second mineral concentrate in a sodium hydroxide aqueous solution to selectively extract the zinc components and obtain a third zinc-containing aqueous solution containing the zinc components, obtain a poorly soluble matter that is not dissolved in the alkali hydroxide aqueous solution, and separate the poorly soluble matter from the third zinc-containing aqueous solution.
  • the first mineral concentrate is sent to the high-temperature high-alkali treatment step as a treated raw material, and the zinc ferrite in the first mineral concentrate is decomposed into zinc oxide components and iron oxide components, the zinc contained in the zinc-containing dust, etc. can be efficiently recovered while more reliably decomposing the zinc ferrite contained in the zinc-containing dust, etc., in a manner that reduces the amount of energy consumed.
  • the alkaline agent is sodium hydroxide
  • the method further includes a halogen washing step in which, prior to the third leaching step, the raw material is washed with an aqueous sodium hydroxide solution having a pH value in the range of 8.5 to 10.5 to wash away the halogen components contained in the raw material, so that the halogen components contained in the zinc-containing dust, etc. can be reliably eluted and washed away.
  • the method further includes a purification step in which metallic zinc is brought into contact with the third zinc-containing aqueous solution to reduce and precipitate metal impurity components that are more noble than zinc in the third zinc-containing aqueous solution, thereby purifying the third zinc-containing aqueous solution, thereby making it possible to recover zinc with reduced amounts of impurities.
  • the zinc recovery process includes an electrolysis step in which electrolysis is performed using the third zinc-containing aqueous solution or a purified third zinc-containing aqueous solution as the electrolyte to obtain electrolytically generated zinc and electrolytic tail solution, and the electrolytic tail solution is sent to the high-temperature, high-alkali treatment step in a state in which the alkaline hydroxide aqueous solution and zinc components remain, and the alkaline hydroxide aqueous solution in the electrolytic tail solution is brought into contact with the raw material or the treated raw material, so that electrolytically generated zinc with reduced impurity contamination can be stably recovered with good yield.
  • the zinc recovery step includes a zinc carbonate separation step in which the zinc components in the third zinc-containing aqueous solution or the purified third zinc-containing aqueous solution are separated as zinc carbonate, and a residual liquid from which the zinc carbonate has been separated is obtained, and the residual liquid is sent to the high-temperature, high-alkali treatment step in a state in which the aqueous alkali hydroxide solution and the zinc components remain, and the aqueous alkali hydroxide solution in the residual liquid is brought into contact with the raw material or the treated raw material, so that zinc carbonate with reduced impurity contamination can be stably recovered with good yield.
  • the method includes a contacting step of contacting a zinc ferrite-containing material containing zinc ferrite with an aqueous alkali hydroxide solution, a heating step of heating the zinc ferrite-containing material and the aqueous alkali hydroxide solution that have been contacted with each other in the contacting step to raise the temperature of the zinc ferrite-containing material and the aqueous alkali hydroxide solution to a temperature that reaches the boiling point of water that exhibits a boiling point rise, and a concentration maintaining step of maintaining the concentration of the alkaline agent contained in the aqueous alkali hydroxide solution when evaporation of water in the aqueous alkali hydroxide solution stops after the temperature reaches the boiling point.
  • the alkaline agent whose concentration is maintained in the concentration maintaining step comes into contact with the zinc ferrite in the zinc ferrite-containing material, thereby decomposing the zinc ferrite into
  • the amount of energy consumed for heating can be reduced, and zinc ferrite contained in zinc-containing dust, etc. can be reliably decomposed while suppressing increases in costs and environmental load. Furthermore, by maintaining the concentration of the alkaline agent contained in the aqueous alkali hydroxide solution at the time when the evaporation of water from the aqueous alkali hydroxide solution stops after the temperature reaches the boiling point in the concentration maintenance process, the pressure resistance of the reaction vessel, such as a sealed vessel, can be reduced at that time, simplifying the structure of the reaction vessel and reducing costs.
  • FIG. 1A is a process diagram of a zinc recovery method according to a first embodiment of the present invention.
  • FIG. 1B is a process diagram of a zinc ferrite decomposition method included in the zinc recovery method of this embodiment.
  • FIG. 2 is a process diagram of a zinc recovery method including a zinc ferrite decomposition method according to a second embodiment of the present invention.
  • FIG. 3 is a process diagram of a zinc recovery method including a zinc ferrite decomposition method according to a third embodiment of the present invention.
  • FIG. 4 is a process diagram of a zinc recovery method including a zinc ferrite decomposition method according to a fourth embodiment of the present invention.
  • FIG. 1 is a diagram showing the steps of a zinc recovery method including a zinc ferrite decomposition method in this embodiment.
  • FIG. 1A is a process diagram of the zinc recovery method in this embodiment
  • FIG. 1B is a process diagram of a zinc ferrite decomposition method included in the zinc recovery method in this embodiment.
  • a dehalogenation cleaning process 101 a high-temperature high-alkali treatment process 102, an electrolytic tail leaching process 103, a cleaning process 104, and an electrolysis process 105 are carried out in this order.
  • the high-temperature high-alkali treatment process 102 corresponds to all the processes of the zinc ferrite decomposition method.
  • the electrolysis process 105 corresponds to the zinc recovery process.
  • electric furnace dust 1 is used as a representative raw material for the recovery method and the decomposition method, but the raw material may be any material that contains at least zinc compounds such as zinc oxide, iron compounds such as iron oxide, and zinc ferrite, which is a compound of iron and zinc.
  • primary dust or secondary dust such as blast furnace dust, blast furnace/converter dust, or RHF (Rotary Hearth Furnace) dust, or zinc concentrate ore, etc. may be used as the raw material.
  • electric furnace dust 1 as a raw material containing zinc compounds such as zinc oxide, iron compounds such as iron oxide, and zinc ferrite, a compound of iron and zinc, is washed with cleaning liquid 2, and halogen components such as chlorine and fluorine components adsorbed to the electric furnace dust 1 are eluted and separated from the electric furnace dust 1, to obtain cleaned electric furnace dust 3.
  • the cleaned electric furnace dust 3 is sent to the next high-temperature high-alkali treatment process 102.
  • an aqueous solution of a strong alkaline agent that is highly effective in eluting halogen components from the electric furnace dust 1 can be suitably used, and specifically, an aqueous solution of sodium hydroxide, which is an aqueous solution of such a strong alkaline agent, can be suitably used as the cleaning liquid 2.
  • the electric furnace dust 1 which has been crushed to a predetermined size or less, is immersed in the aqueous sodium hydroxide solution as the cleaning solution 2, and the immersed electric furnace dust 1 is stirred in the aqueous sodium hydroxide solution for a predetermined time to form a slurry, and the halogen components adhering to the electric furnace dust 1 are eluted from the slurry electric furnace dust 1. If the pH value of the slurry electric furnace dust 1 is less than 8.5, the amount of halogen components eluted from the electric furnace dust 1 cannot be secured as a practical amount, and unnecessary elution of zinc components and lead components occurs from the electric furnace dust 1, so the pH value is preferably 8.5 or more.
  • the pH value of the slurry electric furnace dust 1 exceeds 10.5, the zinc components are extracted from the electric furnace dust 1, and the amount of zinc components in the cleaned electric furnace dust 3 to be sent to the next process is reduced, so the pH value is preferably 10.5 or less.
  • the pH value of the aqueous sodium hydroxide solution as the cleaning solution 2 is also preferably set within the range of 8.5 to 10.5.
  • the electric furnace dust 1 is washed with the washing liquid 2, and the used washing liquid 4 containing the eluted halogen components adsorbed on the electric furnace dust 1 may simply be discharged as waste liquid, or may be reused as the washing liquid 2 to wash the electric furnace dust 1 again within the range in which further chlorine components can be eluted.
  • the reason why the dehalogenation washing process 101 is provided before the high-temperature high-alkali treatment process 102 and the electrolytic tail leaching process 103 is to more appropriately decompose the zinc ferrite in the electric furnace dust 1 and extract the zinc components.
  • the dehalogenation washing process 101 may be omitted.
  • the high-temperature high-alkali treatment process 102 includes a contacting process 102a in which the washed electric furnace dust 3 is brought into contact with the electrolytic tail solution 14 containing sodium hydroxide, a heating and temperature increasing process 102b in which the washed electric furnace dust 3 and the electrolytic tail solution 14 brought into contact with each other in the contacting process 102a are heated to raise the temperature of the washed electric furnace dust 3 and the electrolytic tail solution 14 to a temperature at which the boiling point of water is reached, which causes a boiling point rise, and a concentration maintaining process 102c in which the concentration of the alkaline agent contained in the electrolytic tail solution 14 is maintained for a predetermined time when the evaporation of the water contained in the aqueous alkaline hydroxide solution in the electrolytic tail solution 14 stops after the temperature of the washed electric furnace dust 3 and the electrolytic tail solution 14 reaches the boiling point, and the decomposition reaction of decomposing zinc ferrite into zinc oxide components and iron oxide components is completed by contacting process
  • the electrolytic tail solution 14 containing sodium hydroxide is brought into contact with the washed electric furnace dust 3, from the viewpoint of reusing the sodium hydroxide, which is a strong alkaline agent, in the electrolytic tail solution 14 without wastefully disposing of the electrolytic tail solution 14.
  • the washed electric furnace dust 3 and the electrolytic tail solution 14 containing sodium hydroxide, which are in contact with each other, are heated, and while the boiling point (100° C.) of water contained in the aqueous sodium hydroxide solution in the electrolytic tail solution 14 is increased in the presence of zinc ferrite, which is a hardly soluble substance in the washed electric furnace dust 3, the water is evaporated, and when the temperature of the washed electric furnace dust 3 and the electrolytic tail solution 14, which are heated and increased, enters a temperature range of 150° C.
  • the concentration of sodium hydroxide in the electrolytic tail solution 14 is brought into a concentration range of 70% by weight or more and less than 100% by weight, more preferably 80% by weight or more and less than 100% by weight, while maintaining the temperature of the washed electric furnace dust 3 and the electrolytic tail solution 14.
  • concentration range of 70% by weight or more and less than 100% by weight, more preferably 80% by weight or more and less than 100% by weight, while maintaining the temperature of the washed electric furnace dust 3 and the electrolytic tail solution 14.
  • the lid of the container that contains the cleaned electric furnace dust 3 and the electrolytic tail solution 14 from which all the water in the aqueous sodium hydroxide solution has evaporated is closed to make the container space sealed, and the container environment is switched from an open system to a closed system, and the closed system state, i.e., the temperature of the cleaned electric furnace dust 3 and the electrolytic tail solution 14 is in the range of 150° C. to 250° C., and the concentration of sodium hydroxide in the electrolytic tail solution 14 is in the range of 70% by weight to less than 100% by weight, more preferably 80% by weight to less than 100% by weight, is maintained for a predetermined time of 15 minutes to 5 hours.
  • the decomposition of zinc ferrite in the cleaned electric furnace dust 3 which has been in contact with the sodium hydroxide in the electrolytic tail solution 14 and started to decompose, is completed.
  • the above-mentioned temperature range, concentration range, and the predetermined time for maintaining these conditions are essential conditions for completing the decomposition of zinc ferrite in the cleaned electric furnace dust 3.
  • the temperature of the cleaned electric furnace dust 3 and the electrolytic tail liquid 14 is less than 150° C., there is a problem that zinc ferrite does not dissolve, and if the temperature of the cleaned electric furnace dust 3 and the electrolytic tail liquid 14 exceeds 250° C., there is a problem that more energy than is sufficient to dissolve zinc ferrite is unnecessarily consumed, resulting in a large amount of energy consumption.
  • the concentration of sodium hydroxide in the electrolytic tail liquid 14 is less than 70% by weight, If the concentration of sodium hydroxide in the electrolytic tail solution 14 is 80% by weight or more, this problem disappears.
  • the concentration of sodium hydroxide in the electrolytic tail solution 14 must be less than 100% by weight in order to contain zinc and other components other than sodium hydroxide.
  • the electrolytic tail solution 14 containing the zinc-containing solid matter 6 consisting of the zinc oxide component and the iron oxide component after the decomposition of the zinc ferrite is obtained.
  • the electrolytic tail solution 14 containing the zinc-containing solid matter 6 is cooled and then sent to the next electrolytic tail solution leaching step 103.
  • sodium hydroxide 5 can also be used in combination.
  • the electrolytic tail solution 14 containing sodium hydroxide is brought into contact with the cleaned electric furnace dust 3, i.e., the sodium hydroxide in the electrolytic tail solution 14 is brought into contact with the zinc ferrite in the cleaned electric furnace dust 3, and the zinc ferrite contained in the electric furnace dust 3 is decomposed into zinc oxide components and iron oxide components.
  • the chemical formula for this process is shown in Chemical Formula 1 below.
  • examples of alkaline agents that can be used to decompose zinc ferrite include potassium hydroxide in addition to sodium hydroxide.
  • examples of oxidizing agents added to the electrolytic solution 14 containing sodium hydroxide to promote the decomposition of zinc ferrite include at least one of sodium nitrate and hydrogen peroxide
  • examples of reducing agents added to the electrolytic solution 14 containing sodium hydroxide include at least one of sodium sulfite, sodium thiosulfate, sodium dithionite, hydrazine, and zinc metal.
  • Such alkaline agents, and therefore oxidizing agents and reducing agents are used depending on the state of impurities.
  • the high-temperature high-alkali treatment process 102 is performed in a high-temperature environment, the water contained in the electrolytic solution 14 or sodium hydroxide that has once become an aqueous solution is evaporated into water vapor by introducing the electrolytic solution 14 or sodium hydroxide that has once become an aqueous solution into this process. Therefore, the water vapor is passed through a heat exchanger to cool and liquefy it back into water, while the heat obtained in the heat exchanger can be used to heat the high-temperature high-alkali treatment process 102 or the alkaline aqueous solution leaching process 106 described in the second embodiment.
  • an organic substance that reacts with chlorine to generate a volatile compound to the electrolytic tail solution 14 or the aqueous solution of sodium hydroxide, and immerse the cleaned electric furnace dust 3 in the electrolytic tail solution 14 or the aqueous solution of sodium hydroxide, and when the water in the electrolytic tail solution 14 or the aqueous solution of sodium hydroxide evaporates, the organic substance reacts with the chlorine in the cleaned electric furnace dust 3 and volatilizes as a volatile organic chlorine compound.
  • a practical example of such an organic substance is ethanol, and in this case, ethanol reacts with the chlorine in the cleaned electric furnace dust 3 to generate chloroform, a volatile organic chlorine compound, which is volatilized.
  • a predetermined amount of water 7 is added to the electrolytic tail 14 containing zinc-containing solids 6, typically in a temperature environment below the boiling point of water (100°C), thereby obtaining an aqueous sodium hydroxide solution that is generated or increased in amount, and a difficult-to-dissolve substance containing iron oxide components that is not dissolved in the aqueous sodium hydroxide solution.
  • the zinc oxide components obtained by decomposition of zinc ferrite and the zinc oxide components originally contained in the electric furnace dust 1 are dissolved in the aqueous sodium hydroxide solution, and this aqueous sodium hydroxide solution becomes an aqueous zinc-containing sodium hydroxide solution 8.
  • the mixture of the aqueous zinc-containing sodium hydroxide solution 8 and the difficult-to-dissolve substance containing iron oxide components is filtered, and the aqueous zinc-containing sodium hydroxide solution 8 and the difficult-to-dissolve substance containing iron oxide components are filtered and separated (solid-liquid separation).
  • the aqueous zinc-containing sodium hydroxide solution 8, which is the leaching solution from which the difficult-to-dissolve substance containing iron oxide components has been separated, has its zinc concentration increased and is sent to the next cleaning process 104, and the difficult-to-dissolve substance containing iron oxide components is discharged as residue 9.
  • the zinc-containing sodium hydroxide aqueous solution 8 is brought into contact with metallic zinc 10 to reduce and precipitate metal impurity components more noble than zinc in the zinc-containing sodium hydroxide aqueous solution 8, thereby obtaining a zinc-containing sodium hydroxide aqueous solution 11 that is a more purified version of the zinc-containing sodium hydroxide aqueous solution 8 and precipitated metal impurity components.
  • the cleaning step 104 is a substitution step (cementation step) in which metallic zinc 10 is applied.
  • the thus-purified zinc-containing sodium hydroxide aqueous solution 11 is sent to the next electrolysis step 105, and the metal impurity components are discharged as residue 12.
  • Such metallic zinc 10 is typically introduced into the zinc-containing sodium hydroxide aqueous solution 8 as metallic zinc powder, and the zinc-containing sodium hydroxide aqueous solution 8 to which the metallic zinc powder has been introduced is heated and heated and stirred at high speed while being maintained at a predetermined temperature, thereby promoting the cementation reaction, and as a result, the metal impurity components more noble than zinc in the zinc-containing sodium hydroxide aqueous solution 8 can be rapidly precipitated.
  • the metallic zinc 10 may be applied as a metallic zinc plate instead of metallic zinc powder.
  • the zinc-containing sodium hydroxide aqueous solution 8 is caused to flow toward a metallic zinc plate fixed so as to be stationary, and the cementation reaction is similarly promoted by contacting the metallic zinc plate.
  • metallic zinc powder it is assumed that the entire surface of the metallic zinc powder is covered with precipitated metallic impurity components during the cementation reaction, and the central part of the metallic zinc powder cannot contribute to the cementation reaction.
  • the contact area between the metallic zinc plate and the zinc-containing sodium hydroxide aqueous solution 8 can be set with a high degree of freedom, so that the contact area can be increased, which can reliably promote the cementation reaction, and the metallic zinc plate on which the metallic impurity components have precipitated can also be quickly replaced.
  • the metallic zinc plate may be rotated relative to the flow of the zinc-containing sodium hydroxide aqueous solution 8.
  • the cleaning process 104 may be omitted when the amount of metallic impurity components more noble than zinc in the zinc-containing sodium hydroxide aqueous solution 8 is small.
  • the cleaning process 104 may also include a deferronization/demanganese process in which deferronization/demanganese is performed by air oxidation or by adding an oxidizing agent, a desiliconization/defluorination process in which desiliconization/defluorination is performed by adding a reducing agent such as a calcium-based compound, and a process in which dechlorination is performed by adding copper oxide (I) or silver nitrate, and these processes may also be combined as necessary.
  • a deferronization/demanganese process in which deferronization/demanganese is performed by air oxidation or by adding an oxidizing agent
  • a desiliconization/defluorination process in which desiliconization/defluorination is performed by adding a reducing agent such as a calcium-based compound
  • a process in which dechlorination is performed by adding copper oxide (I) or silver nitrate may also be combined as necessary.
  • the halogen components are already reduced in the dehalogenation cleaning process 101 and that the chlorine components can be reduced in the high-temperature high-alkali treatment process 102, it is preferable to apply at least one of the substitution process and deferronization/demanganese, or to further apply a desiliconization/defluorination process with the intention of desiliconization.
  • electrolysis is performed using the purified zinc-containing aqueous sodium hydroxide solution 11 as the electrolyte, and the electrolytic product, electrolytically produced zinc 13, is precipitated on the cathode side and recovered as a solid by solid-liquid separation.
  • the electrolytic tail solution 14, which is the electrolyte after recovery of the electrolytically produced zinc 13, can be discharged as is and used as waste liquid, but since it contains sodium hydroxide, it is more rational and preferable to return the electrolytic tail solution 14 as is to the high-temperature, high-alkali treatment step 102. Therefore, typically, the electrolytic tail solution 14 is brought into contact with the electric furnace dust 3 that has been washed in the high-temperature, high-alkali treatment step 102.
  • the zinc component may be left in the electrolytic tail solution 14, and the zinc-containing electrolytic tail solution 14 may be returned as is to the high-temperature, high-alkali treatment step 102.
  • the electrolytic tail solution 14 is used as the electrolyte in the electrolysis step 105 while increasing the zinc concentration through at least the high-temperature high-alkali treatment step 102 and the electrolytic tail solution leaching step 103, so to ensure that the electrolysis is carried out reliably, it is preferable that the solution contains sodium hydroxide with a concentration of 200 g/L or more and zinc with a concentration of 10 g/L or more.
  • Example 1 In the high-temperature high-alkali treatment step 102, the electric furnace dust 3 (weight 150 g) after the completion of the dehalogenation cleaning in the dehalogenation cleaning step 101 and the electrolytic tail solution 14 (volume 1 L) containing NaOH (concentration 400 g/L) and Zn (concentration 50 g/L) were charged into an iron crucible and heated. At this time, a thermocouple sensor was charged into the electrolytic tail solution 14 containing the electric furnace dust 3, and when the temperature of the electrolytic tail solution 14 reached 150°C, the heated state was maintained.
  • the electrolytic tail solution 14 initially boiled, but the amount of evaporation of the moisture decreased as the boiling point rose, and after a certain time had passed since the temperature of the electrolytic tail solution 14 reached 160°C, the evaporation of the moisture ceased.
  • the iron crucible that had been open until then was closed and sealed and the temperature of the electrolytic tail solution 14 was maintained at 160°C by constant temperature management for one hour. After one hour, the heating was stopped, and the temperature of the electrolytic tail solution 14 containing the solidified matter 6 was cooled to less than 100°C.
  • the electrolytic tail solution leaching process 103 water was poured into the electrolytic tail solution 14 containing the solidified matter 6, and the solution was diluted with water 7 to the original volume of 1L. Thereafter, the electrolytic tail solution 14 was heated and stirred until the temperature of the solution reached 100°C, and the remaining solidified matter 6 was dissolved to obtain a slurry. This slurry was filtered to separate the Fe residue 9 and the Zn leaching solution 8 (Zn concentration 110g/L).
  • the Fe residue 9 was washed with water and dried, while in the cleaning process 104, the Zn leaching solution 8 was used as an oxidation cleaning solution, and an oxidizing agent (KMnO4, H2O2) was added, and the solution was stirred for 1H, and the precipitate was filtered.
  • this leaching solution was used as a Ca cleaning solution, and CaO was added, and the precipitate was filtered after stirring for 1H.
  • the leachate was brought into contact with zinc metal (powder or plate-like) 10 for 24 hours to perform cementation at a temperature of 60°C, removing impurities such as Cu, Pb, Cd, and Ni.
  • the leachate 11 which had undergone a series of purification steps up to the cementation step, was used as an electrolyte to perform electrolytic extraction in the electrolysis step 105.
  • the electrolytic extraction conditions were set to a current density of 1200A per square meter, an electrolyte concentration of 400g/L NaOH and 50g/L Zn, and an electrolyte temperature of 40°C, respectively, to obtain electrolytically produced zinc 13 with a purity of 99.995%.
  • a liquid supply tank was used to supply Zn in a circulating manner so that the electrolyte supply Zn concentration was 55g/L and the electrolyte tail Zn concentration was 50g/L.
  • a part of the electrolytic tail solution 14 was extracted and used as the leachate 8 in the subsequent electrolytic tail solution leaching step 103 via the alkaline aqueous solution before evaporation in the high-temperature high-alkali treatment step 102, and the Zn concentration in the electrolytic tail solution 14 was increased from 50 g/L to 110 g/L by the electrolytic tail solution leaching.
  • the analytical values of the leachate 11 (purified zinc-containing aqueous sodium hydroxide solution) after the series of purification steps up to cementation were shown in Table 1 below, and the concentrations of all the analyzed components were below the lower limit of measurement.
  • the method includes a contacting step 102a in which the raw material 1 containing zinc components and zinc ferrite or the treated raw material 3 obtained by treating the raw material 1 is brought into contact with the aqueous alkali hydroxide solution 5, 14, a heating step 102b in which the raw material 1 or the treated raw material 3 and the aqueous alkali hydroxide solution 5, 14 brought into contact with each other in the contacting step 102a are heated to raise the temperature of the raw material 1 or the treated raw material 3 and the aqueous alkali hydroxide solution 5, 14 to a temperature at which the temperature reaches the boiling point of water exhibiting a boiling point rise, and a concentration maintaining step 102c in which the concentration of the alkaline agent contained in the aqueous alkali hydroxide solution 5, 14 is maintained when the evaporation of the water in the aqueous alkali hydroxide solution 5, 14 stops after the temperature reaches the boiling point, and the alkaline agent whose concentration is
  • the concentration maintenance step 102c the concentration of the alkaline agent contained in the aqueous alkali hydroxide solution 5, 14, 22 is maintained when the evaporation of water from the aqueous alkali hydroxide solution 5, 14, 22 stops after the temperature reaches the boiling point, so that the pressure resistance of the reaction vessel, such as a sealed vessel, can be reduced, simplifying the structure of the reaction vessel and reducing costs.
  • a contact step 102a in which zinc ferrite-containing materials 1, 3 containing zinc ferrite are brought into contact with aqueous alkali hydroxide solutions 5, 14, a heating and temperature raising step 102b in which the zinc ferrite-containing materials 1, 3 and the aqueous alkali hydroxide solutions 5, 14 brought into contact with each other in the contact step 102a are heated to raise the temperature of the zinc ferrite-containing materials 1, 3 and the aqueous alkali hydroxide solutions 5, 14 to a temperature that reaches the boiling point of water exhibiting a boiling point rise, and a heating and temperature raising step 102c in which the temperature of the aqueous alkali hydroxide solutions 5, 14 is raised to a temperature that reaches the boiling point of water exhibiting a boiling point rise after the temperature reaches the boiling point.
  • a concentration maintaining step 102c for maintaining the concentration of the alkaline agent contained in the aqueous alkali hydroxide solution 5, 14 when the evaporation of the water in the aqueous alkali hydroxide solution 5, 14 stops.
  • the alkaline agent whose concentration is maintained in the concentration maintaining step 102c comes into contact with the zinc ferrite in the zinc ferrite-containing material 1, 3, thereby decomposing the zinc ferrite into zinc oxide components and iron oxide components. This makes it possible to reliably decompose the zinc ferrite contained in the zinc-containing dust, etc., while suppressing the amount of energy consumed for heating and suppressing increases in costs and environmental loads.
  • the pressure resistance of the reaction vessel such as a sealed vessel, can be reduced, and the structure of the reaction vessel can be simplified to reduce costs.
  • FIG. 2 is a diagram showing the steps of a zinc recovery method including a zinc ferrite decomposition method in this embodiment.
  • the zinc recovery method according to this embodiment differs from the zinc recovery method according to the first embodiment mainly in that it has an alkaline aqueous solution leaching process 106 immediately following the dehalogenation washing process 101.
  • This embodiment will be described with a focus on this difference, and the same components will be given the same reference numerals and their description will be omitted or simplified.
  • the alkaline aqueous solution leaching step 106 is provided immediately after the dehalogenation cleaning step 101.
  • the reason why the dehalogenation cleaning step 101 is provided before the alkaline aqueous solution leaching step 106 is to more appropriately extract the zinc component in the electric furnace dust 1.
  • the cleaned electric furnace dust 3 is brought into contact with an aqueous sodium hydroxide solution, which is an aqueous solution of sodium hydroxide 5, prior to the high-temperature high-alkali treatment step 102, and the zinc component contained in the cleaned electric furnace dust 3 is dissolved in the aqueous sodium hydroxide solution to selectively extract it, thereby obtaining a zinc-containing sodium hydroxide aqueous solution 15 containing the zinc component and obtaining a difficult-to-dissolve substance 16 containing zinc ferrite that is not dissolved in the aqueous sodium hydroxide solution.
  • an aqueous sodium hydroxide solution which is an aqueous solution of sodium hydroxide 5
  • the zinc component contained in the cleaned electric furnace dust 3 is dissolved in the aqueous sodium hydroxide solution to selectively extract it, thereby obtaining a zinc-containing sodium hydroxide aqueous solution 15 containing the zinc component and obtaining a difficult-to-dissolve substance 16 containing zinc ferrite that is not
  • a mixture of the zinc-containing sodium hydroxide aqueous solution 15 and the difficult-to-dissolve substance 16 containing the iron oxide component is filtered to separate the zinc-containing sodium hydroxide aqueous solution 15 and the difficult-to-dissolve substance 16 containing the iron oxide component (solid-liquid separation).
  • Sodium hydroxide is used as the strong alkaline agent because it allows efficient extraction of zinc components and can be shared with the strong alkaline agent used in the high-temperature, high-alkali treatment step 102.
  • the zinc-containing sodium hydroxide aqueous solution 15 thus obtained is sent to the next cleaning step 104, while the obtained zinc ferrite-containing insoluble matter 16 is sent to the high-temperature high-alkali treatment step 102, where the zinc ferrite is decomposed into zinc oxide and iron oxide components.
  • the zinc-containing solidified matter 6 from which the zinc ferrite has been decomposed is sent to the next electrolytic tail leaching step 103, where it becomes the zinc-containing sodium hydroxide aqueous solution 8, and is sent to the alkaline aqueous solution leaching step 106, where the zinc component contained in the zinc-containing sodium hydroxide aqueous solution 8 is selectively extracted and becomes part of the zinc-containing sodium hydroxide aqueous solution 15.
  • the zinc-containing sodium hydroxide aqueous solution 8 may be used in combination with sodium hydroxide 5 or without sodium hydroxide 5, and brought into contact with the washed electric furnace dust 3.
  • an alkaline aqueous solution leaching process 106 is provided, and the zinc-containing solidified material 6 containing zinc ferrite is sent from the alkaline aqueous solution leaching process 106 to the high-temperature, high-alkali treatment process 102, and the zinc-containing solidified material 6 in which the zinc ferrite has been decomposed is sent to the alkaline aqueous solution leaching process 106 as a zinc-containing sodium hydroxide aqueous solution 8 via the subsequent electrolytic tail leaching process 103.
  • the high-temperature, high-alkali treatment process 102 requires a higher temperature environment than the alkaline aqueous solution leaching process 106 and consumes a larger amount of energy. Therefore, by treating the electric furnace dust 1 as the zinc-containing raw material containing zinc ferrite not only in the high-temperature, high-alkali treatment process 102 but also in the alkaline aqueous solution leaching process 106, the treatment time in the high-temperature, high-alkali treatment process 102 can be shortened, thereby realizing a reduction in the amount of energy consumed.
  • the electrolytic tail solution 14 may be returned to the alkaline aqueous solution leaching process 106, and used alone or together with the sodium hydroxide aqueous solution as the alkaline aqueous solution for contacting the washed electric furnace dust 3.
  • Example 2 In the high-temperature high-alkali treatment step 102, the dust 16 after the alkaline aqueous solution leaching step 106 (containing zinc components in which zinc oxide was dissolved by the alkaline aqueous solution leaching and the zinc components in zinc ferrite remained: weight 70 g) and the electrolytic tail solution 14 (NaOH concentration 450 g/L, Zn concentration 50 g/L: volume 100 mL) were charged in a 500 mL sealable iron container and heated and stirred.
  • the electrolytic tail solution 14 NaOH concentration 450 g/L, Zn concentration 50 g/L: volume 100 mL
  • the electrolytic tail solution 14 in contact with the dust 16 after the alkaline aqueous solution leaching in the open iron container boiled, and when the temperature of the electrolytic tail solution 14 reached 200°C, the iron container was closed and sealed, and the temperature of the electrolytic tail solution 14 was maintained within a range of 180°C to 200°C for one hour. After one hour, the heating was stopped, and the liquid temperature of the electrolytic tail solution 14 containing the solidified matter 6 was cooled to less than 110°C.
  • water was started to be poured into the electrolytic tail solution 14 containing the solidified matter 6, and the solution was diluted to the original volume of 100 mL by filling up the solution with a measuring tape.
  • the electric furnace dust 3 (weight 175 g) after completion of the dehalogenation cleaning in the dehalogenation cleaning process 101, the Zn leaching solution 8 (volume 200 mL) after completion of the high-temperature high-alkali treatment process 102 and the electrolytic tail solution leaching process 103, and the electrolytic tail solution 14 (volume 800 ml) were added to a sealable iron reaction vessel and heated while stirring to raise the liquid temperature to 120°C, and this liquid temperature was maintained for one hour. At this time, the reaction vessel was closed and sealed to avoid the influence of the latent heat of evaporation, and the liquid temperature was allowed to reach 120°C. The dissolved liquid was then filtered to separate the solid and liquid.
  • a solid (iron residue) 16 with a dry weight of about 70 g was collected. This is the primary leaching completed dust and will be used as the raw material for the next process, the high-temperature high-alkali treatment process 102.
  • the liquid separated from the solid was made into a leachate 15, in which the concentration of Zn was increased to about NaOH (concentration 450 g/L) and Zn (concentration 120 g/L).
  • the leachate 15 was used as an oxidation cleaning solution, and an oxidizing agent (KMnO4, H2O2) was added, and the precipitate was filtered after stirring for 1 hour.
  • the leachate was used as a Ca cleaning solution, and CaO was added, and the precipitate was filtered after stirring for 1 hour. Furthermore, the leachate was brought into contact with zinc metal (powder or plate-like) 10 for cementation at a liquid temperature of 60°C for 24 hours to remove impurities such as Cu, Pb, Cd, and Ni.
  • the leachate 11 which had undergone a series of cleaning steps up to this cementation, was used as an electrolyte to perform electrolytic extraction in the electrolysis step 105.
  • the electrolytic extraction conditions were set to a current density of 12000A per square meter, an electrolyte concentration of 450g/L NaOH and 55g/L Zn, and an electrolyte temperature of 60°C, and electrolytic zinc 13 with a purity of 99.995% was obtained.
  • a liquid supply tank was used to circulate and supply the electrolyte so that the Zn concentration of the electrolytic feed solution was 55g/L and the Zn concentration of the electrolytic tail solution was 50g/L.
  • a part of the electrolytic tail solution 14 was extracted and passed through an alkaline aqueous solution before evaporation in a high-temperature high-alkali treatment step 102, and used as the leaching solutions 8 and 15 in the subsequent electrolytic tail solution leaching step 103 and alkaline aqueous solution leaching step 106, and the Zn concentration of 50g/L was increased to 120g/L by dissolving in water and alkaline aqueous solution.
  • the concentrations of all analyzed components were below the lower limit of measurement, similar to the values shown in (Table 1) of Experimental Example 1.
  • the raw material 1 or the treated raw material 3 is contacted with an aqueous sodium hydroxide solution, and the zinc component contained in the raw material 1 or the treated raw material 3 is dissolved in the aqueous sodium hydroxide solution 5, 14 and selectively extracted to obtain a second zinc-containing aqueous solution 15 containing the zinc component, and a second leaching step 106 is further provided in which a difficult-to-dissolve material 16 containing zinc ferrite that is not dissolved in the aqueous sodium hydroxide solution 5, 14 is obtained, and the difficult-to-dissolve material 16 containing zinc ferrite is sent to the high-temperature high-alkali treatment step 102 as a treated raw material and decomposed into zinc oxide components and iron oxide components, and in the first leaching step 103, the zinc oxide component is dissolved in the aqueous sodium hydroxide solution to obtain a fourth zinc-containing
  • FIG. 3 is a diagram showing the steps of a zinc recovery method including a zinc ferrite decomposition method in this embodiment.
  • the zinc recovery method according to this embodiment differs from the zinc recovery method according to the second embodiment mainly in that it has a magnetic separation process 107 between the dehalogenation washing process 101 and the alkaline aqueous solution leaching process 106.
  • This embodiment will be described with a focus on this difference, and the same components are given the same reference numerals, and their description will be omitted or simplified.
  • the magnetic separation process 107 can also be performed before the dehalogenation washing process 101 if magnetic separation is possible for the electric furnace dust 3 before washing.
  • Such a magnetic separation process 107 may also be applied to the zinc recovery method according to the first embodiment.
  • a magnetic separation process 107 is provided immediately following the dehalogenation washing process 101, and prior to the alkaline aqueous solution leaching process 106, the magnetic separation process 107 applies a magnetic force to the washed electric furnace dust 3 via a magnet, typically an electromagnet, and separates the washed electric furnace dust 3 into attached mineral concentrate 18 consisting of components (mainly zinc ferrite and iron components) attached to the magnet and residual mineral concentrate 19 that is not attached to the magnet other than the attached mineral concentrate 18 in the washed electric furnace dust 3, depending on the magnetic strength of the components in the dust.
  • a commercially available wet high magnetic force magnetic separator can be used in the magnetic separation process 107.
  • the attached mineral concentrate 18 is sent to the high-temperature high-alkali treatment process 102 where it is contacted with molten sodium hydroxide, and the zinc ferrite in the attached mineral concentrate 18 is decomposed into zinc oxide and iron oxide components, and the zinc-containing solidified material 6 from which the zinc ferrite has been decomposed is sent to the next electrolytic tailings leaching process 103.
  • the zinc-containing solidified material 6 from which the zinc ferrite has been decomposed is contacted with water 7 to obtain a zinc-containing sodium hydroxide aqueous solution 8 and a residue 9 consisting of poorly soluble matter containing iron oxide components.
  • a part 9' or all of the residue 9' may be sent to the alkaline aqueous solution leaching process 106 to selectively extract the zinc components.
  • the residual mineral concentrate 19 is sent to the alkaline aqueous solution leaching process 106, where the zinc components contained in the residual mineral concentrate 19 are dissolved in an aqueous sodium hydroxide solution and selectively extracted, to obtain a zinc-containing aqueous sodium hydroxide solution 15 containing the zinc components, and a refractory matter 16 that is not dissolved in the aqueous sodium hydroxide solution.
  • the zinc-containing aqueous sodium hydroxide solution 15 thus obtained is sent to the next cleaning process 104, while the refractory matter 16 obtained is discharged as residue.
  • a part or all of the refractory matter 16 may be sent to the high-temperature high-alkali treatment process 102 to decompose the zinc ferrite into zinc oxide and iron oxide components.
  • the electrolytic tail solution 14 that contacted the dust 16 after the alkaline aqueous solution leaching in the open iron container boiled, and when the temperature of the electrolytic tail solution 14 reached 180°C, the iron container was closed and sealed, and the temperature of the electrolytic tail solution 14 was maintained within a range of 180°C to 200°C for one hour. After one hour, the heating was stopped, and the liquid temperature of the electrolytic tail solution 14 containing the solidified matter 6 was cooled to less than 120°C.
  • the electrolytic tail solution leaching process 103 water was started to be poured into the electrolytic tail solution 14 containing the solidified matter 6, and the solution was diluted to the original volume of 100 mL by filling up the solution with a measuring tape, and then 200 mL of the electrolytic tail solution 14 was added to make the total volume 300 mL.
  • the solution was stirred while being heated until the liquid temperature reached 100° C., and was held in this state for one hour. After confirming that the zinc component had dissolved, the slurry was filtered. After filtration, the cake of the solid (iron leaching residue 9) was washed and analyzed, and it was confirmed that 98% or more of the Zn in the electric furnace dust 1 had dissolved in the Zn leaching solution 8.
  • the iron leaching residue 9 can also be input into the alkaline aqueous solution leaching process 106 when zinc dissolution is insufficient.
  • the non-magnetic dust 19 (which refers to the components that did not adhere to the magnet out of the total weight of 175 g of the electric furnace dust, weighing 108 g) that had passed through the magnetic separation process 107 and the filtrate 8 (volume 300 mL) after completion of the high-temperature high-alkali treatment process 102 and the electrolytic tailings leaching process 103 were charged into an iron reaction vessel and heated while stirring to raise the liquid temperature to 120°C, and this liquid temperature was maintained for one hour. After one hour had passed, the solution was filtered and separated into solid and liquid to obtain solid 16 (iron residue).
  • the leachate 15 was used as an oxidation cleaning solution, and an oxidizing agent (KMnO4, H2O2) was added, and the mixture was stirred for 1 Hr, after which the precipitate was filtered off.
  • the leachate was used as a Ca cleaning solution, and CaO was added, and the mixture was stirred for 1 Hr, after which the precipitate was filtered off.
  • the leachate was brought into contact with zinc metal (powder or plate-like) 10, and cementation was performed at a liquid temperature of 60°C for 24 hours to remove impurities such as Cu, Pb, Cd, and Ni.
  • the leachate 11 which had undergone a series of cleaning steps up to this cementation, was used as an electrolyte to perform electrolytic extraction in the electrolytic step 105.
  • the conditions for electrolytic extraction were set to a current density of 1200A per square meter, an electrolyte concentration of 450g/L for NaOH and 55g/L for Zn, and an electrolyte temperature of 60°C, respectively, and electrolytic extraction was performed, resulting in electrolytically produced zinc 13 with a purity of 99.995%.
  • a circulating supply tank was used to supply the electrolyte so that the Zn concentration of the electrolytic feed solution was 55 g/L and the Zn concentration of the electrolytic tail solution was 50 g/L.
  • a portion of the electrolytic tail solution 14 was extracted and passed through the alkaline aqueous solution before evaporation in the high-temperature, high-alkali treatment process 102, and used as leachates 8 and 15 in the subsequent electrolytic tail solution leaching process 103 and alkaline aqueous solution leaching process 106, and the Zn concentration of 50 g/L was increased to 120 g/L by dissolving in water and alkaline aqueous solution.
  • the analytical values of the leachate 11 (purified zinc-containing sodium hydroxide aqueous solution) after the purification by cementation was completed were all below the lower limit of measurement, similar to the values shown in (Table 1) of Experimental Example 1.
  • a magnetic force is applied to the raw material 1 or the treated raw material 3 via a magnet, and depending on the magnetic strength of the components in the raw material 1 or the treated raw material 3, a first mineral concentrate 18 consisting of components attached to the magnet and a second mineral concentrate 19 not attached to the magnet are separated in a magnetic separation step 107, and the second mineral concentrate 19 is sent to a third zinc-containing aqueous solution 15 containing the zinc component by dissolving it in an aqueous sodium hydroxide solution 5, 14 for selective extraction.
  • the first mineral concentrate 18 is sent to the high-temperature high-alkali treatment step 102 as a treated raw material, and the zinc ferrite in the first mineral concentrate 18 is decomposed into zinc oxide components and iron oxide components. This allows the zinc contained in the zinc-containing dust to be efficiently recovered while more reliably decomposing the zinc ferrite contained in the zinc-containing dust in a manner that reduces the amount of energy consumed.
  • FIG. 4 is a diagram showing the steps of a zinc recovery method including a zinc ferrite decomposition method in this embodiment.
  • the zinc recovery method according to this embodiment differs from the zinc recovery method according to the third embodiment mainly in that it has a zinc carbonate separation step 108 instead of the electrolysis step 105 as a zinc recovery step.
  • This embodiment will be described with a focus on this difference, and the same components are given the same reference numerals, and their description will be omitted or simplified. Note that this zinc carbonate separation step 108 may be applied in place of the electrolysis step 105 of the zinc recovery method according to the first and second embodiments.
  • the zinc carbonate separation process 108 involves contacting the zinc-containing sodium hydroxide aqueous solution 11 that has been through the cleaning process 104 with carbon dioxide gas 20, and separating the zinc component from the zinc-containing sodium hydroxide aqueous solution 11 as zinc carbonate 21.
  • carbon dioxide 20 is blown into the zinc component in the zinc-containing aqueous sodium hydroxide solution 11 to precipitate zinc carbonate, as shown in the following chemical formula (Chemical Formula 3), and the precipitated zinc carbonate is filtered to obtain solid zinc carbonate 21.
  • the zinc carbonate 21 can also be used as a product if it is washed with water and then dried.
  • the residual liquid 22 from the zinc carbonate separation step 108 contains sodium hydroxide, and is returned to the high-temperature high-alkali treatment step 102.
  • zinc oxide can also be obtained by roasting the solid zinc carbonate 21.
  • Example 4 As in Experimental Example 3, the Zn concentration was increased from 50 g/L to 120 g/L by dissolving in an alkaline aqueous solution, while carrying out the purification step 104. Carbon dioxide gas 20 was blown into the leachate 11 after purification to precipitate zinc carbonate 21, which was then filtered and recovered. As for the analytical values of the leachate 11 after purification by cementation (purified zinc-containing aqueous sodium hydroxide solution), the concentrations of all the analyzed components were below the lower limit of measurement, similar to the values shown in Table 1 of Experimental Example 1.
  • the zinc recovery process includes a zinc carbonate separation process in which the zinc components in the zinc-containing aqueous solution 8, 15 or the purified zinc-containing aqueous solution 8, 15 11 are separated as zinc carbonate 21, and the residual liquid 22 from which the zinc carbonate 21 has been separated is obtained.
  • the residual liquid 22 is sent to the high-temperature, high-alkali treatment process 102 in a state in which the alkaline hydroxide aqueous solution and zinc components remain, and the alkaline hydroxide aqueous solution in the residual liquid 22 is brought into contact with the raw material 1 or the treated raw materials 3, 16, 18, so that zinc carbonate with reduced impurity contamination can be stably recovered with good yield.
  • the present invention provides a zinc recovery method that can recover zinc contained in zinc-containing dust while reliably decomposing zinc ferrite contained in zinc-containing dust and the like, while suppressing the amount of energy consumed for heating and suppressing increases in costs and environmental loads, and a zinc ferrite decomposition method that decomposes such zinc ferrite.
  • the method can be applied to a wide range of raw materials, including electric furnace dust generated during the melting and smelting of scrap in the electric furnace process, which is one of the iron-making processes, as well as primary or secondary dust such as blast furnace dust, blast furnace/converter dust, or RHF (Rotary Hearth Furnace) dust, and zinc-containing dust such as ore burnt from zinc concentrate.
  • electric furnace dust generated during the melting and smelting of scrap in the electric furnace process
  • primary or secondary dust such as blast furnace dust, blast furnace/converter dust, or RHF (Rotary Hearth Furnace) dust
  • zinc-containing dust such as ore burnt from zinc concentrate.

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JP2014526614A (ja) * 2011-09-09 2014-10-06 カナダス ケミカル，エルエルシー 酸化亜鉛の精製方法
WO2022118927A1 (ja) 2020-12-04 2022-06-09 株式会社キノテック 亜鉛の製造方法
WO2022130462A1 (ja) * 2020-12-14 2022-06-23 日揮グローバル株式会社 亜鉛の回収方法

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Publication number Priority date Publication date Assignee Title
JP2014526614A (ja) * 2011-09-09 2014-10-06 カナダス ケミカル，エルエルシー 酸化亜鉛の精製方法
WO2022118927A1 (ja) 2020-12-04 2022-06-09 株式会社キノテック 亜鉛の製造方法
WO2022130462A1 (ja) * 2020-12-14 2022-06-23 日揮グローバル株式会社 亜鉛の回収方法

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