Method for removing copper in steel scraps

Abstract

In producing high-quality steel with use of copper-containing steel scraps as an iron source, the copper-containing steel scraps are melted with addition of carbon to produce hot metal for steelmaking, then, copper contained in the hot metal is removed by sulfur-containing flux, and sulfur contained in the hot metal is removed. With this method, the copper in the steel scraps can be removed efficiently and without the need for large facilities. Preferably, the sulfur-containing flux used is flux having Na 2 S as the main component. The treatment for removing copper in the hot metal is preferably carried out with use of refining equipment with mechanical stirrer or by the flux injecting method. Besides, it is preferable that a shaft furnace having a coke bed formed inside is used to produce hot metal having a higher concentration of sulfur for the copper removal treatment.

1 - 14 . (canceled) 
     
     
         15 . A method for removing copper in steel scraps comprising the steps of:
 melting copper-containing steel scraps with addition of carbon to produce hot metal for steelmaking;   then, removing copper contained in the hot metal with use of sulfur-containing flux; and   removing sulfur contained in the hot metal.   
     
     
         16 . The method of claim  14 , wherein the sulfur-containing flux has Na 2 S as a main component. 
     
     
         17 . The method of claim  14 , wherein a material having Na 2 CO 3  as a main component and an iron-sulfur alloy are used as starting materials of the sulfur-containing flux. 
     
     
         18 . The method of claim  14 , wherein the hot metal before copper removal by the sulfur-containing flux has a temperature of 1200° C. or higher and 1500° C. or lower, and contains carbon at a concentration of 2% by mass or more and copper at a concentration of 0.1% or more by mass and 1.0% by mass or less. 
     
     
         19 . The method of  claim 18 , wherein the hot metal before copper removal by the sulfur-containing flux has a temperature of 1250° C. or higher and 1350° C. or lower. 
     
     
         20 . The method of claim  14 , wherein the hot metal before copper removal by the sulfur-containing flux contains sulfur at a concentration of 0.01% by mass or more. 
     
     
         21 . The method of claim  14 , wherein removing of the copper contained in the hot metal is carried out by refining equipment with mechanical stirrer. 
     
     
         22 . The method of claim  14 , wherein removing of the copper contained in the hot metal is carried out by injecting the sulfur-containing flux with a carrier gas into the hot metal in a refining vessel. 
     
     
         23 . The method of claim  14 , wherein removing of the copper contained in the hot metal is carried out by injecting at least a part of a starting material of the sulfur-containing flux with a carrier gas into the hot metal in a refining vessel. 
     
     
         24 . The method of claim  14 , wherein melting of the copper-containing steel scraps with addition of the carbon is conducted by using a shaft furnace having a coke bed formed inside. 
     
     
         25 . The method of  claim 20 , wherein melting of the copper-containing steel scraps with addition of the carbon is conducted by using a shaft furnace having a coke bed formed inside. 
     
     
         26 . The method claim  14 , wherein melting of the copper-containing steel scraps with addition of the carbon is conducted by using a shaft furnace having a coke bed formed inside, and the sulfur-containing flux is supplied to the hot metal passing through a tilting runner at casthouse from the shaft furnace to a hot metal vessel thereby to remove the copper in the hot metal. 
     
     
         27 . The method of claim  14 , wherein removing of the sulfur contained in the hot metal is carried out by refining equipment with mechanical stirrer. 
     
     
         28 . The method of claim  14 , wherein the hot metal from which the copper is removed with use of the sulfur-containing flux is mixed with blast furnace hot metal, and then, the sulfur contained in the hot metal that is mixed with the blast furnace hot metal is removed.