Process for producing metallic iron

Abstract

A method for manufacturing metallic iron from a raw material mixture containing a carbonaceous reducing agent and an iron oxide-containing material, has a step of determining a target temperature of initial molten slag formation corresponding to a predetermined target carbon concentration in the metallic iron, the initial molten slag containing a gangue component, an unreduced iron oxide, and an ash component of the carbonaceous reducing agent, and being first produced in the raw material mixture by heating thereof; a step of preparing the raw material mixture producing a composition of the initial molten slag corresponding to the target temperature; and a step of heating the raw material mixture to reduce and melt the raw material mixture and to produce the initial molten slag. By this manufacturing method, metallic iron having a target carbon concentration can be efficiently manufactured.

1 . A method for manufacturing metallic iron from a raw material mixture containing a carbonaceous reducing agent and an iron oxide-containing material, comprising:
 determining a target temperature of initial molten slag formation corresponding to a predetermined target carbon concentration in the metallic iron, the initial molten slag containing a gangue component, an unreduced iron oxide, and an ash component of the carbonaceous reducing agent, and being first produced in the raw material mixture by heating;   preparing the raw material mixture producing a composition of the initial molten slag corresponding to the target temperature; and   heating the raw material mixture to reduce and melt the raw material mixture and to produce the initial molten slag.   
   
   
       2 . The method according to  claim 1 ,
 wherein in the preparation step, a slag-forming component is mixed with the iron oxide-containing material.   
   
   
       3 . The method according to  claim 1 ,
 wherein in the preparation step, a slag-forming component is mixed with the carbonaceous reducing agent.   
   
   
       4 . The method according to  claim 1 ,
 wherein the raw material mixture further contains an additional raw material, and   in the preparation step, a slag-forming component is mixed with the additional raw material.   
   
   
       5 . The method according to  claim 1 ,
 further comprising a step of charging an additive containing a slag-forming component before the heating step.   
   
   
       6 . The method according to  claim 1 ,
 wherein in the heating step, a slag-forming agent containing a slag-forming component is added.   
   
   
       7 . The method according to  claim 1 ,
 wherein the target temperature is determined by a multi-component phase diagram composed of a gangue component, unreduced iron oxide remaining in reduction, and an ash component of a carbonaceous reducing agent.   
   
   
       8 . The method according to  claim 1 ,
 wherein a relationship between a temperature forming the initial molten slag and a carbon concentration in the metallic iron is evaluated beforehand, and the target temperature is determined by the target carbon concentration in accordance with the relationship.   
   
   
       9 . The method according to  claim 1 ,
 further comprising, before the heating step, a step of setting a target content of the unreduced iron oxide in the initial molten slag and calculating a target reduction degree of the iron oxide-containing material corresponding to the target content,   wherein in the heating step, until a reduction degree of the iron oxide-containing material reaches the target reduction degree, a heating temperature pattern or a reduction potential is adjusted, and simultaneously heating is performed.   
   
   
       10 . The method according to  claim 1 ,
 wherein in the heating step, heating is performed based on a melting point of slag containing unreduced iron oxide in reduction.