Method for reducing chromium containing raw material

Abstract

An object of the present invention is to provide a method for reducing a chromium-containing material at a high chromium reduction degree. In the method of the present invention, a mixture of a feedstock containing chromium oxide and a carbonaceous reductant is heated and reduced by radiation heating in a moving hearth furnace. The average rate of raising the temperature of the mixture in the reduction is preferably 13.6° C./s or higher in the period from the initiation of the radiation heating of the mixture until the mixture reaches 1,114° C.

1 . A method for reducing a chromium-containing material, comprising a mixing step of mixing a chromium-containing material comprising chromium oxide and iron oxide and a carbonaceous reductant to provide a mixture; and a reducing step of heating, and reducing the mixture with a rapid temperature rise by radiation heating in a moving hearth furnace to provide a reduced mixture.  
   
   
       2 . The method for reducing a chromium-containing material according to  claim 1 , wherein the average rate of raising the temperature of the mixture in the reducing step is 13.6° C./s or higher in the period from the initiation of the radiation heating of the mixture until the mixture reaches 1,114° C.  
   
   
       3 . The method for reducing a chromium-containing material according to  claim 1 , wherein the reducing step is performed at 1,250° C. to 1,400° C.  
   
   
       4 . The method for reducing a chromium-containing material according to  claim 1 , further comprising a reducing and melting step of melting the reduced mixture provided in the reducing step by successive radiation heating to provide a reduced molten material.  
   
   
       5 . The method for reducing a chromium-containing material according to  claim 4 , further comprising a solidifying step of cooling and solidifying the reduced molten material provided in the reducing and melting step in the moving hearth furnace to provide a reduced solid; and a separating step of separating the reduced solid into metal and slag.  
   
   
       6 . The method for reducing a chromium-containing material according to  claim 4 , wherein the reducing step is performed at 1,250° C. to 1,400° C.; and the reducing and melting step is performed at a temperature higher than that in the reducing step within the range of 1,350° C. to 1,700° C.  
   
   
       7 . The method for reducing a chromium-containing material according to  claim 1 , wherein a carbonaceous atmosphere-adjusting agent is charged together with the mixture onto the hearth of the moving hearth furnace in the reducing step.