Method for producing reduced iron

Abstract

A method for producing reduced iron includes: a step of preparing a mixed raw material; a mixed raw material charging step; and a reducing step. In the step of preparing the mixed raw material, the mixed raw material which contains iron ore (X) containing iron ore with a high content of zinc (A) which contains 0.01 mass % or more of zinc and 50 mass % or more of iron, and a carbonaceous solid reducing material is prepared. In the mixed raw material charging step, the mixed raw material is charged on a movable hearth. In the reducing step, a reduced product is obtained by reducing the mixed raw material charged on the movable hearth by supplying heat to the mixed raw material from above the hearth.

1 . A method for producing reduced iron comprising:
 preparing a mixed raw material which includes iron ore (X) containing high zinc iron ore (A) which contains 0.01 mass % or more of zinc and 50 mass % or more of iron, and a carbonaceous solid reducing material;   a mixed raw material charging step of charging the mixed raw material on a hearth of a movable hearth furnace;   and   a reducing step of reducing the mixed raw material charged on the movable hearth by supplying heat to the mixed raw material from above the hearth to obtain a reduced product.   
     
     
         2 . The method according to  claim 1 , wherein the high zinc iron ore (A) contains 0.01 to 0.5 mass % of zinc and 50 to 70 mass % of iron. 
     
     
         3 . The method according to  claim 1 , wherein the high zinc iron ore (A) has a mixing ratio of 10 to 100 mass % with respect to the iron ore (X). 
     
     
         4 . The method according to  claim 1 , wherein the mixed raw material charging step comprises charging an agglomerated mixed raw material on the movable hearth. 
     
     
         5 . The method according to  claim 1 , wherein the reducing step comprises reducing the mixed raw material at a heating temperature of 1200° C. or more. 
     
     
         6 . The method according to  claim 5 , wherein the heating temperature is 1250° C. or more and less than 1400° C. 
     
     
         7 . The method according to  claim 1 , wherein the reducing step comprises reducing the mixed raw material charged on the movable hearth by supplying heat to the mixed raw material from above the hearth, to produce the reduced iron in a state where the mixed raw material is not melted or the mixed raw material is melted only partially. 
     
     
         8 . The method according to  claim 1 ,
 further comprising a recovering step of recovering crude zinc oxide from dust generated in the movable hearth furnace,   and   wherein the step of preparing the raw material comprises preparing a mixed raw material which contains iron ore (X) containing high zinc iron ore (A) which contains 0.01 mass % or more of zinc and 50 mass % or more of iron, zinc-containing dust, and a carbonaceous solid reducing material.   
     
     
         9 . The method according to  claim 8 , wherein the mixed raw material has an average zinc concentration of 0.45 mass % or more. 
     
     
         10 . The method according to  claim 9 , wherein the average zinc concentration is 0.45 to 0.60 mass %. 
     
     
         11 . The method according to  claim 8 , wherein the zinc-containing dust is at least one dust selected from a group consisting of dust generated in a blast furnace, dust generated in a converter and dust generated in an electric furnace. 
     
     
         12 . The method according to  claim 1 ,
 further comprising a recovering step of obtaining the recovered dust by recovering dust generated in the movable hearth furnace, and   wherein the step of preparing the raw material comprises preparing a mixed raw material which contains iron ore (X) containing high zinc iron ore (A) which contains 0.01 mass % or more of zinc and 50 mass % or more of iron, the recovered dust, and a carbonaceous solid reducing material.   
     
     
         13 . The method according to  claim 1 , further comprising:
 recovering dust generated in the movable hearth furnace;   charging the recovered dust on the movable hearth; and   supplying heat from above the hearth to obtain crude zinc oxide generated in the movable hearth furnace.   
     
     
         14 . The method according to  claim 1 , further comprising a melting step of melting the reduced product. 
     
     
         15 . The method according to  claim 1 ,
 further comprising a melting step of melting the reduced product, and   the mixed raw material contains iron ore (X) containing high zinc iron ore (A) which contains 0.01 mass % or more of zinc and 50 mass % or more of iron, a carbonaceous solid reducing material, and a slag-making material.   
     
     
         16 . The method according to  claim 14 , wherein the melting step comprises melting the reduced product at a heating temperature of 1400° C. or more. 
     
     
         17 . The method according to  claim 16 , wherein the heating temperature is 1450° C. or more and 1500° C. or less. 
     
     
         18 . The method according to  claim 1 ,
 further comprising a melting step of melting the reduced product; and a recovering step of recovering crude zinc oxide from dust generated in the movable hearth furnace; and   wherein the step of preparing the raw material comprises preparing a mixed raw material which contains iron ore (X) containing high zinc iron ore (A) which contains 0.01 mass % or more of zinc and 50 mass % or more of iron, zinc-containing dust, a carbonaceous solid reducing material, and a slag-making material.   
     
     
         19 . The method according to  claim 18 , wherein the mixed raw material has an average zinc concentration of 0.45 mass % or more. 
     
     
         20 . The method according to  claim 19 , wherein the average zinc concentration is 0.45 to 0.60 mass %. 
     
     
         21 . The method according to  claim 18 , wherein the zinc-containing dust is at least one dust selected from the group consisting of dust generated in a blast furnace, dust generated in a converter and dust generated in an electric furnace. 
     
     
         22 . The method according to  claim 1 ,
 further comprising a melting step of melting the reduced product; and a recovering step of obtaining the recovered dust by recovering dust generated in the movable hearth furnace, and   wherein the step of preparing the raw material comprises preparing a mixed raw material which contains iron ore (X) containing high zinc iron ore (A) which contains 0.01 mass % or more of zinc and 50 mass % or more of iron, the recovered dust, a carbonaceous solid reducing material, and a slag-making material.   
     
     
         23 . The method according to  claim 1 , further comprising:
 melting the reduced product;   recovering dust generated in the movable hearth furnace;   charging the recovered dust on the movable hearth; and   obtaining crude zinc oxide from dust generated in the movable hearth furnace by supplying heat from above the hearth.   
     
     
         24 . The method according to  claim 1 , further comprising, prior to the mixed raw material charging step, a carbon material charging step of charging a carbon material on the movable hearth for stacking the mixed raw material on the carbon material charged on the movable hearth.