Method for recovering zinc from electric furnace steelmaking dust and device for recovering zinc from electric furnace steelmaking dust

Abstract

A method and a device for recovering zinc from electric furnace steelmaking dust, which are capable of recovering high-purity metal zinc for relatively short time. A Ca mixing and heating means obtains ZnO and 2CaO.Fe 2 O 3 by mixing electric furnace steelmaking dust with calcium compound and performing heat treatment in a non-reducing atmosphere at not lower than 960° C. and not exceeding 1100° C. for one to three hours. An iron powder mixing means mixes the ZnO and 2CaO.Fe 2 O 3 with iron powder, and compact the mixture. A reduction and volatilization means obtains a solid metal zinc piece by disposing a green compact in a decompression container 21 , decompressing and heating the inside of the decompression container to generate zinc vapor, and cooling and coagulating the zinc vapor. A zinc acquisition means acquires lumpy zinc by immersing the metal zinc piece in a NaCl—KCl based multi-component chloride flux and cooling the flux solution.

1 . A method for recovering zinc from electric furnace steelmaking dust, comprising:
 a Ca mixing and heating step for obtaining ZnO and 2CaO.Fe 2 O3 by mixing electric furnace steelmaking dust with calcium compound containing Ca of a molar amount not less than an equivalent amount of the molar amount of Fe in the electric furnace steelmaking dust and performing heat treatment in a non-reducing atmosphere at not lower than 960° C. and not exceeding 1100° C. for one to three hours;   a iron powder mixing step for mixing the ZnO and 2CaO.Fe 2 O3 obtained by the said Ca mixing and heating step with iron powder of the molar amount not less than the equivalent amount of the molar amount of the said ZnO, and compacting the mixture;   a reduction and volatilization step for obtaining a solid zinc piece by disposing a green compact by the said iron powder mixing step in a decompression container, decompressing and heating an inside of the decompression container to generate zinc vapor, and cooling and coagulating the zinc vapor; and   a zinc acquisition step for acquiring lumpy zinc by immersing the zinc piece obtained by the said reduction and volatilization step in an NaCl—KCl based multi-component chloridic flux having a melting point lower than the melting point of zinc and cooling the flux solution.   
     
     
         2 . A method for recovering zinc from electric furnace steelmaking dust, comprising:
 a Ca mixing and heating step for obtaining ZnO and 2CaO.Fe 2 O3 by mixing electric furnace steelmaking dust with calcium compound containing Ca of a molar amount not less than an equivalent amount of the molar amount of Fe in the electric furnace steelmaking dust and performing heat treatment in a non-reducing atmosphere at not lower than 960° C. and not exceeding 1100° C. for one to three hours;   a leaching step for immersing the ZnO and 2CaO.Fe 2 O3 obtained by the said Ca mixing and heating step in an aqueous alkali or neutral solution to selectively leach the ZnO in the said solution; and   a electrowinning step for electrolizing the solution in which the ZnO is leached by the said leaching step so that zinc is deposited on a cathode.   
     
     
         3 . The method for recovering zinc from electric furnace steelmaking dust according to  claim 2 , wherein, in the said leaching step, the ZnO and 2CaO.Fe 2 O3 obtained by the said Ca mixing and heating step is immersed in the said aqueous solution at not lower than 70° C. and not exceeding 100° C. 
     
     
         4 . The method for recovering zinc from electric furnace steelmaking dust according to  claim 2 , wherein the said aqueous solution in the said leaching step is an aqueous NaOH solution or an aqueous NH4Cl solution. 
     
     
         5 . The method for recovering zinc from electric furnace steelmaking dust according to  claim 1 , wherein the said calcium compound is comprised at least one of quick lime, a lime stone, and slaked lime. 
     
     
         6 . A device for recovering zinc from electric furnace steelmaking dust, comprising:
 a Ca mixing and heating means configured to obtain ZnO and 2CaO.Fe 2 O3 by mixing electric furnace steelmaking dust with calcium compound containing Ca of a molar amount not less than an equivalent amount of the molar amount of Fe in the electric furnace steelmaking dust and performing heat treatment in a non-reducing atmosphere at not lower than 960° C. and not exceeding 1100° C. for one to three hours;   an iron powder mixing means configured to mix the ZnO and 2CaO.Fe 2 O3 obtained by the said Ca mixing and heating means with iron powder of the molar amount not less than the equivalent amount of the molar amount of the ZnO, and compact the mixture;   a reduction and volatilization means that includes a decompression container and is configured to obtain a solid zinc piece by disposing a green compact by the said iron powder mixing means in the said decompression container, decompressing and heating an inside of the said decompression container to generate zinc vapor, and cooling and coagulating the said zinc vapor; and   a zinc acquisition means configured to acquire lumpy zinc by immersing the zinc piece obtained by the said reduction and volatilization means in a NaCl—KCl based multi-component chloride flux having a melting point lower than the melting point of zinc and cooling the flux solution.   
     
     
         7 . A device for recovering zinc from electric furnace steelmaking dust, comprising:
 a Ca mixing and heating means configured to obtain ZnO and 2CaO.Fe 2 O3 by mixing electric furnace steelmaking dust with calcium compound containing Ca of a molar amount not less than an equivalent amount of the molar amount of Fe in the electric furnace steelmaking dust and performing heat treatment in a non-reducing atmosphere at not lower than 960° C. and not exceeding 1100° C. for one to three hours;   a leaching means configured to immerse the ZnO and 2CaO.Fe 2 O3 obtained by the said Ca mixing and heating means in an aqueous alkali or neutral solution to selectively leach the ZnO in the said solution; and   an electrowinning means configured to electrolize the said aqueous solution in which the ZnO is leached by the said leaching means so that zinc is deposited on a cathode.   
     
     
         8 . The device for recovering zinc from electric furnace steelmaking dust according to  claim 7 , wherein, the said leaching means is configured to immerse the ZnO and 2CaO.Fe 2 O3 obtained by the Ca mixing and heating means in the said aqueous solution at not lower than 70° C. and not exceeding 100° C. 
     
     
         9 . The device for recovering zinc from electric furnace steelmaking dust according to  claim 7 , wherein the said aqueous solution in the leaching means is an aqueous NaOH solution or an aqueous NH4Cl solution. 
     
     
         10 . The device for recovering zinc from electric furnace steelmaking dust according to  claim 6 , wherein the said calcium compound is comprised at least one of quick lime, a lime stone, and slaked lime.