Method of manufacturing metal iron

Abstract

The present invention is intended to provide a method for producing metallic iron, which comprises the steps of supplying a mixture containing a carbonous reducing agent and iron oxides onto a hearth of a reduction melting furnace of the moving hearth type, heating the mixture for reduction melting of the iron oxides, cooling thus-obtained metallic iron, and discharging the metallic iron to the outside of the furnace for recovery. The method can easily remove or repair the surface of a hearth even when metallic iron powder is buried in the hearth surface or even when the hearth surface suffers from slag infiltration and erosion, can increase an availability factor and maintainability of the hearth, and is suitably practiced for long-term continuous operation. The present invention resides in a method for producing metallic iron, wherein a hearth material is laid in the form of a layer on the hearth prior to supply of the mixture, thereby forming a renewable hearth capable of being renewed, and the metallic iron is produced while renewing a part or the whole of the renewable hearth, which has deteriorated during operation, with the hearth material.

1 . A method for producing metallic iron, the method comprising the steps of supplying a mixture containing a carbonous reducing agent and iron oxides onto a hearth of a reduction melting furnace of the moving hearth type, heating the mixture for reduction melting of the iron oxides, cooling thus-obtained metallic iron, and discharging the metallic iron to the outside of said furnace for recovery, wherein a hearth material is laid in the form of a layer on said hearth prior to supply of the mixture, thereby forming a renewable hearth capable of being renewed, and the metallic iron is produced while renewing a part or the whole of said renewable hearth, which has deteriorated during operation, with the hearth material.  
     
     
         2 . A method for producing metallic iron, the method comprising the steps of supplying a mixture containing a carbonous reducing agent and iron oxides onto a hearth of a reduction melting furnace of the moving hearth type, heating the mixture for reduction melting of the iron oxides, cooling thus-obtained metallic iron, and discharging the metallic iron to the outside of said furnace for recovery, wherein a hearth material is laid in the form of a layer on said hearth prior to supply of the mixture, thereby forming a renewable hearth capable of being renewed, and the metallic iron is produced while a hearth surface is renewed by charging the hearth material to lie in the form of a layer on said renewable hearth which has deteriorated during operation, or by supplying the hearth material onto the surface of the deteriorated renewable hearth.  
     
     
         3 . The producing method according to  claim 2 , wherein the hearth material is filled in dents formed in the surface of the hearth layer during operation of said reduction melting furnace.  
     
     
         4 . The producing method according to any one of  claims 1  to  3 , wherein the whole or a part of said renewable hearth, which has deteriorated during operation, is removed periodically or continuously.  
     
     
         5 . The producing method according to any one of  claims 1  to  4 , wherein a thickness of said renewable hearth is adjusted.  
     
     
         6 . The producing method according to  claim 4  or  5 , wherein after removing said renewable hearth is renewed by supplying the hearth material after removing said renewable hearth.  
     
     
         7 . The producing method according to any one of  claims 1  to  6 , wherein the hearth material contains a substance having a high melting point and being corrosion-resistant against produced slag.  
     
     
         8 . The producing method according to  claim 7 , wherein the hearth material further contains a carbonous substance.  
     
     
         9 . The producing method according to any one of  claims 1  to  8 , wherein the substance having a high melting point contains oxides including alumina and/or magnesia, or silicon carbide.  
     
     
         10 . The producing method according to any one of  claims 1  to  9 , wherein the hearth material further contains a sintering accelerator.  
     
     
         11 . A method for producing metallic iron, the method comprising the steps of supplying a mixture containing a carbonous reducing agent and iron oxides onto a renewable hearth capable of being renewed, which is formed by charging a hearth material to lie in the form of a layer, heating the mixture for reduction melting of the iron oxides, cooling thus-obtained metallic iron, and discharging the metallic iron to the outside of said furnace for recovery, wherein after supplying a coolant to said renewable hearth, which has deteriorated during operation, to solidify molten iron residing on the surface of said renewable hearth, said renewable hearth is removed together with the residing iron, and the metallic iron is produced while renewing a part or the whole of said renewable hearth with the hearth material.  
     
     
         12 . The producing method according to any one of  claims 1  to  11 , wherein said renewable hearth is softened before renewing said renewable hearth.  
     
     
         13 . The producing method according to any one of  claims 1  to  12 , wherein after charging the hearth material to lie in the form of a layer on said hearth to form said renewable hearth, an atmosphere modifier containing a powdery carbonous substance is laid in the form of a layer and the mixture is then supplied.  
     
     
         14 . The producing method according to  claim 13 , wherein the hearth material is mixed in said atmosphere modifier.  
     
     
         15 . The producing method according to  claim 13  or  14 , wherein said atmosphere modifier is laid in the form of two or more layers.  
     
     
         16 . The producing method according to any one of  claims 1  to  15 , wherein a carbonous material layer is provided between said hearth and said renewable hearth or between said renewable hearth and a renewable hearth supplied onto said renewable hearth.