Method for producing pig iron

Abstract

A method for producing pig iron using a blast furnace including a tuyere, the method including charging a first layer containing an iron ore material and a second layer containing coke alternately in the blast furnace and reducing and melting the iron ore material in the first layer while injecting an auxiliary reductant into the blast furnace by hot air blown from the tuyere. The iron ore material contains a reduced iron molded product obtained by compression molding of reduced iron, the auxiliary reductant contains pulverized coal, a blending amount of the reduced iron is greater than or equal to 200 kg per ton of pig iron to be produced, a reducing agent ratio of a reducing agent containing the coke and the pulverized coal is less than or equal to 440 kg/tp, and a pulverized coal ratio is greater than or equal to 130 kg/tp.

1 . A method for producing pig iron using a blast furnace comprising a tuyere, the method comprising:
 charging a first layer comprising an iron ore material and a second layer comprising coke alternately in the blast furnace; and   reducing and melting the iron ore material in the first layer while injecting an auxiliary reductant into the blast furnace by hot air blown from the tuyere, wherein   the iron ore material comprises a reduced iron molded product obtained by compression molding of reduced iron,   the auxiliary reductant comprises pulverized coal,   a blending amount of the reduced iron is greater than or equal to 200 kg per ton of pig iron to be produced,   a reducing agent ratio of a reducing agent comprising the coke and the pulverized coal is less than or equal to 440 kg/tp, and   a pulverized coal ratio is greater than or equal to 130 kg/tp.   
     
     
         2 . The method of  claim 1 , wherein
 the iron ore material comprises self-fluxing pellets comprising MgO, and   the self-fluxing pellets have a MgO content of greater than or equal to 1.0% by mass and a basicity of greater than or equal to 1.0.   
     
     
         3 . The method of  claim 1 , wherein a lower furnace heat ratio is less than or equal to 0.5. 
     
     
         4 . The method of  claim 3 , wherein an oxygen enrichment rate of the hot air is less than or equal to 2.5% by volume. 
     
     
         5 . The method of  claim 3 , wherein a nitrogen enrichment rate of the hot air is greater than or equal to 0% by volume. 
     
     
         6 . The method of  claim 1 , wherein the iron ore material further comprises an aggregate that is not the reduced iron molded product. 
     
     
         7 . The method of  claim 1 , wherein the reduced iron molded product has an aluminum oxide content of 0 to 1.5 mass %, based on a total mass of reduced iron molded product. 
     
     
         8 . The method of  claim 2 , wherein the self-fluxing pellets have a MgO content of less than or equal to 4% by mass. 
     
     
         9 . The method of  claim 1 , wherein the pulverized coal has a maximum grain size of less than or equal to 500 μm. 
     
     
         1 . A method for producing pig iron using a blast furnace comprising a tuyere, the method comprising:
 charging a first layer comprising an iron ore material and a second layer comprising coke alternately in the blast furnace; and   reducing and melting the iron ore material in the first layer charged, while injecting an auxiliary reductant into the blast furnace by hot air blown from the tuyere,   
       wherein:
 the iron ore material comprises a reduced iron molded product obtained by compression molding of reduced iron, 
 the auxiliary reductant comprises pulverized coal, 
 a blending amount of the reduced iron is greater than or equal to 200 kg per ton of pig iron to be produced, and 
 a reducing agent ratio of a reducing agent comprising the coke and the pulverized coal is less than or equal to 440 kg/tp, and a pulverized coal ratio is greater than or equal to 130 kg/tp. 
 
     
     
         2 . The method for producing pig iron according to  claim 1 ,
 wherein:   the iron ore material comprises self-fluxing pellets comprising MgO, and   the self-fluxing pellets have a MgO content of greater than or equal to 1.0% by mass and a basicity of greater than or equal to 1.0.   
     
     
         3 . The method for producing pig iron according to  claim 1 or 2 , wherein a lower furnace heat ratio is less than or equal to 0.5. 
     
     
         4 . The method for producing pig iron according to  claim 3 , wherein an oxygen enrichment rate of the hot air is less than or equal to 2.5% by volume. 
     
     
         5 . The method for producing pig iron according to  claim 3 , wherein a nitrogen enrichment rate of the hot air is greater than or equal to 0% by volume.