Method for producing granular metallic iron

Abstract

A method for producing granular metallic iron by heating and reducing a raw material mixture which includes an iron oxide-containing material, a carbonaceous reductant and a Li 2 O supplying material in a thermal reduction furnace, wherein the iron oxide-containing material includes a hematite-containing material, and the raw material mixture includes at least Fe, Ca, Mg, Si and Li as constituent elements in such a manner that slag which forms as a by-product during heating and reduction contains CaO, MgO, SiO 2 and Li 2 O, has a Li 2 O content of 0.05% by mass or more, and the slag has a basicity [(CaO+MgO)/SiO 2 ] in a range of from 1.5 to 1.9. This method enables granular metallic iron to be produced at a high productivity even when a hematite-containing material is used as the iron oxide-containing material.

1 . A method for producing granular metallic iron, comprising:
 charging a raw material mixture comprising an iron oxide-comprising material, a carbonaceous reductant, and a Li 2 O supplying material, into a thermal reduction furnace;   heating the raw material mixture and reducing iron oxide in the raw material mixture with the carbonaceous reductant to form metallic iron and to form slag as a by-product;   causing the metallic iron to coalesce into granules while separating the metallic iron from the slag; and then   cooling and solidifying the metallic iron,   wherein the iron oxide-comprising material comprises a hematite-comprising material, and   the raw material mixture comprises at least Fe, Ca, Mg, Si, and Li, as constituent elements in such a manner that   the slag comprises CaO, MgO, SiO 2 , and Li 2 O,   Li 2 O content in the slag is 0.05% by mass or more, and   the slag has a basicity, (CaO+MgO)/SiO 2 , in a range of from 1.5 to 1.9.   
     
     
         2 . A method for producing granular metallic iron, comprising:
 charging a Li 2 O supplying material and a raw material mixture comprising an iron oxide-comprising material and a carbonaceous reductant into a thermal reduction furnace;   heating the Li 2 O supplying material and the raw material mixture and reducing iron oxide in the raw material mixture with the carbonaceous reductant, to form metallic iron and to form slag as a by-product;   causing the metallic iron to coalesce into granules while separating the metallic iron from the slag; and then   cooling and solidifying the metallic iron,   wherein   the iron oxide-comprising material comprises a hematite-comprising material, and   one of the raw material mixture and the Li 2 O supplying material comprises at least one element from among Fe, Ca, Mg, Si, and Li, as a constituent element, and the other one of the raw material mixture and the Li 2 O supplying material comprises at least the remaining elements as constituent elements in such a manner that   the slag comprises CaO, MgO, SiO 2 , and Li 2 O,   Li 2 O content in the slag is 0.05% by mass or more, and   the slag has a basicity, (CaO+MgO)/SiO 2 , in a range of from 1.5 to 1.9.   
     
     
         3 . The method according to  claim 1 , wherein the hematite-comprising material comprises 0.30% by mass or more of Al 2 O 3  with respect to the 100% by mass of hematite-comprising material. 
     
     
         4 . The method according to  claim 1 , wherein MgO content in the slag is from 4 to 10% by mass. 
     
     
         5 . The method according to  claim 1 , wherein the Li 2 O supplying material is at least one compound selected from the group consisting of Li 2 O and Li 2 CO 3 . 
     
     
         6 . The method according to  claim 1 , wherein the raw material mixture further comprises dolomite ore. 
     
     
         7 . The method according to  claim 1 , wherein the raw material mixture further comprises at least one compound selected from the group consisting of CaO and CaCO 3 . 
     
     
         8 . The method according to  claim 1 , wherein the raw material mixture further comprises at least one compound selected from the group consisting of MgO and MgCO 3 . 
     
     
         9 . The method according to  claim 2 , wherein the hematite-comprising material comprises 0.30% by mass or more of Al 2 O 3  with respect to the 100% by mass of hematite-comprising material. 
     
     
         10 . The method according to  claim 2 , wherein MgO content in the slag is from 4 to 10% by mass. 
     
     
         11 . The method according to  claim 3 , wherein MgO content in the slag is from 4 to 10% by mass. 
     
     
         12 . The method according to  claim 9 , wherein MgO content in the slag is from 4 to 10% by mass. 
     
     
         13 . The method according to  claim 2 , wherein the Li 2 O supplying material is at least one compound selected from the group consisting of Li 2 O and Li 2 CO 3 . 
     
     
         14 . The method according to  claim 3 , wherein the Li 2 O supplying material is at least one compound selected from the group consisting of Li 2 O and Li 2 CO 3 . 
     
     
         15 . The method according to  claim 9 , wherein the Li 2 O supplying material is at least one compound selected from the group consisting of Li 2 O and Li 2 CO 3 . 
     
     
         16 . The method according to  claim 2 , wherein the raw material mixture further comprises dolomite ore. 
     
     
         17 . The method according to  claim 3 , wherein the raw material mixture further comprises dolomite ore. 
     
     
         18 . The method according to  claim 9 , wherein the raw material mixture further comprises dolomite ore. 
     
     
         19 . The method according to  claim 2 , wherein the raw material mixture further comprises at least one compound selected from the group consisting of CaO and CaCO 3 . 
     
     
         20 . The method according to  claim 2 , wherein the raw material mixture further comprises at least one compound selected from the group consisting of MgO and MgCO 3 .