Ferronickel and process for producing raw material for ferronickel smelting

Abstract

The present invention provides a process that is useful in producing ferronickel having a high Ni content at low cost with high efficiency and reproducibility even if a low-grade feedstock containing nickel oxide is used. In particular, a feedstock containing nickel oxide and iron oxide is mixed with a carbonaceous reductant, the mixture is formed into agglomerates with an agglomerator, and the agglomerates are heated and reduced in a moving hearth furnace, whereby reduced agglomerates in which the Ni metallization degree is 40% or more and the Fe metallization degree is at least 15% less than the Ni metallization degree are prepared by adjusting the retention time of the agglomerates placed in the moving hearth furnace. The reduced agglomerates, in which the Ni component has been primarily reduced as compared with the Fe component, are smelted in a smelting furnace, whereby ferronickel having a high Ni content is obtained.

1 . A process for producing a ferronickel, comprising: 
 mixing a feedstock comprising nickel oxide and iron oxide with a carbonaceous reductant to prepare a mixture;    heating and reducing the mixture in a moving hearth furnace to prepare a reduced mixture; and    smelting the reduced mixture in a smelting furnace to prepare the ferronickel.    
     
     
         2 . The process for producing a ferronickel according to  claim 1 , wherein the retention time of the mixture placed in the moving hearth furnace is adjusted such that the Ni metallization degree of the reduced mixture is 40% or more and the Fe metallization degree of the reduced mixture is at least 15% less than the Ni metallization degree thereof.  
     
     
         3 . The process for producing a ferronickel according to  claim 2 , wherein the Ni metallization degree is 85% or more.  
     
     
         4 . The process for producing a ferronickel according to  claim 1 , further comprising 
 cooling the reduced mixture to a temperature ranging from 450° C. to 1100° C. in the moving hearth furnace to maintain the reduced mixture at that temperature for 17 seconds or more or    discharging the reduced mixture from the moving hearth furnace to place the reduced mixture in another vessel to cool the reduced mixture to a temperature ranging from 450° C. to 1100° C. in the vessel to maintain the reduced mixture at that temperature for 17 seconds or more.    
     
     
         5 . A process for producing a ferronickel, comprising: 
 mixing a feedstock comprising nickel oxide and iron oxide with a carbonaceous reductant to prepare a mixture;    heating and reducing the mixture in a moving hearth furnace to prepare a reduced mixture wherein the Ni metallization degree is 40% or more and the Fe metallization degree is at least 15% less than the Ni metallization degree to heat and melt the reduced mixture to prepare a reduced melt;    cooling the reduced melt in the moving hearth furnace to prepare a reduced solid or discharging the reduced melt from the moving hearth furnace to cool the reduced melt to prepare a reduced solid; and    separating the reduced melt into a metal and a slag to prepare the ferronickel.    
     
     
         6 . The process for producing a ferronickel according to  claim 5 , wherein the Ni metallization degree is 85% or more.  
     
     
         7 . A process for producing a feedstock for ferronickel production, comprising: 
 mixing a composition comprising nickel oxide and iron oxide with a carbonaceous reductant to prepare a mixture; and    heating and reducing the mixture in a moving hearth furnace to prepare the feedstock for ferronickel production wherein the Ni metallization degree is 40% or more and the Fe metallization degree is at least 15% less than the Ni metallization degree.    
     
     
         8 . The process for producing a feedstock for ferronickel production according to  claim 7 , wherein the Ni metallization degree is 85% or more.