Method and apparatus for making metallic iron

Abstract

A method of making metallic iron in which a compact, containing iron oxide such as iron ore or the like and a carbonaceous reductant such as coal or the like, is used as material, and the iron oxide is reduced through the application of heat, thereby making metallic iron. In the course of this reduction, a shell composed of metallic iron is generated and grown on the surface of the compact, and slag aggregates inside the shell. This reduction continues until substantially no iron oxide is present within the metallic iron shell. Subsequently, heating is further performed to melt the metallic iron and slag. Molten metallic iron and molten slag are separated one from the other, thereby obtaining metallic iron with a relatively high metallization ratio. Through the employment of an apparatus for making metallic iron of the present invention, the above-described method is efficiently carried out, and metallic iron having a high iron purity can be made continuously as well as productively not only from iron oxide having a high iron content but also from iron oxide having a relatively low iron content.

1 . A method, comprising: 
 heating a first compact, thereby forming a reduced compact;    wherein said first compact comprises 
 (i) iron oxide, and  
 (ii) a carbonaceous reducing agent; and said reduced compact comprises  
 (iii) a shell, comprising metallic iron, and  
 (iv) molten slag, inside said shell.  
   
     
     
         2 . The method of  claim 1 , wherein substantially no iron oxide is present within said shell.  
     
     
         3 . The method of  claim 1 , further comprising heating said reduced compact, thereby allowing said slag to flow out from inside said shell.  
     
     
         4 . The method of  claim 3 , wherein during said further heating part of said shell is melted, thereby separating molten slag from said metallic iron.  
     
     
         5 . The method of  claim 4 , wherein during said further heating said metallic iron is carburized, thereby reducing the melting point of said metallic iron.  
     
     
         6 . The method of  claim 1 , further comprising heating said reduced compact, thereby melting said metallic iron and separating said metallic iron from said slag.  
     
     
         7 . The method of  claim 6 , wherein during said further heating said metallic iron is carburized, thereby reducing the melting point of said metallic iron.  
     
     
         8 . The method of  claim 1 , further comprising allowing said slag to form aggregates, and separating said aggregates from said metallic iron.  
     
     
         9 . The method of  claim 1 , wherein said heating is performed at a maximum temperature of not less than the melting point of said slag, and not more than the melting point of said metallic iron.  
     
     
         10 . The method of  claim 1 , wherein during said heating said iron oxide is reduced first by solid phase reduction, followed by liquid phase reduction, and said heating is continued until substantially no iron oxide is present.  
     
     
         11 . The method of  claim 1 , wherein said reduced compact comprises 5% by weight or less of FeO.  
     
     
         12 . The method of  claim 11 , wherein said reduced compact comprises 2% by weight or less of FeO.  
     
     
         13 . The method of  claim 1 , wherein said slag comprises 5% by weight or less of FeO.  
     
     
         14 . The method of  claim 13 , wherein said slag comprises 2% by weight or less of FeO.  
     
     
         15 . The method of  claim 1 , wherein said shell is closed and continuous.  
     
     
         16 . The method of  claim 1 , wherein said beating is performed at a temperature of 1350-1540° C.  
     
     
         17 . An object, comprising; 
 (a) a shell comprising metallic iron, and    (b) slag, inside said shell.    
     
     
         18 . The object of  claim 17 , wherein said slag is molten.  
     
     
         19 . The object of  claim 17 , wherein said slag comprises 5% by weight or less of FeO.  
     
     
         20 . The object of  claim 17 , wherein said slag comprises 2% by weight or less of FeO.  
     
     
         21 . The method of  claim 1 , wherein said first compact is in the form of grains or aggregates and undergoes reduction through the application of heat while being moved in a horizontal direction.  
     
     
         22 . The method of  claim 21 , wherein said first compact is placed on an iron belt having edge portions comprising walls formed at said edge portions thereof to prevent said first compact from falling off said iron belt, and said first compact undergoes reduction through the application of heat while being moved in a horizontal direction.  
     
     
         23 . The method of  claim 1 , wherein said first compact is in the form of grains or aggregates and undergoes reduction through the application of heat while being placed on a horizontal plane.  
     
     
         24 . The method of  claim 1 , wherein said first compact is in the form of grains or aggregates and undergoes reduction through the application of heat while being rolled.  
     
     
         25 . The method of  claim 1 , wherein said first compact is in the form of grains or aggregates and undergoes reduction through the application of heat while falling downward.  
     
     
         26 . The method of  claim 1 , wherein said first compact is in an elongated form, and undergoes reduction through the application of heat while being moved downward in an upright position.  
     
     
         27 . The method of  claim 26 , wherein said first compact is continuously formed into an elongated form and fed to a section where reduction is performed through the application of heat.  
     
     
         28 . The method of  claim 26 , wherein said first compact comprises iron mesh serving as a support therefor.  
     
     
         29 . The method of  claim 26 , wherein said first compact comprises an iron bar or wire serving as a core thereof.  
     
     
         30 . The method of  claim 1 , wherein said first compact is in an elongated form and undergoes reduction through the application of heat while being moved downward along a slope.  
     
     
         31 . The method of  claim 30 , wherein said first compact is continuously fed on an iron belt to a section where reduction is performed through the application of heat.  
     
     
         32 . An apparatus for manufacturing metallic iron by reducing a compact of iron oxide containing a carbonaceous reducing agent, comprising: 
 a thermal reduction apparatus for reducing the compact through the application of heat, thereby forming a shell comprising metallic iron and slag inside the shell;    a beat-melting apparatus for melting the shell and the slag; and    a separator for separating the molten iron from the molten slag.    
     
     
         33 . The apparatus of  claim 32 , wherein the compact is in the form of grains or aggregates and said thermal reduction apparatus comprises a mechanism for reducing the compact through the application of heat while moving the compact in a horizontal direction.  
     
     
         34 . The apparatus of  claim 33 , wherein said mechanism comprises an endless rotary member and a hearth located on said member and used for placing the compact thereon.  
     
     
         35 . The apparatus of  claim 34 , wherein said hearth is provided with separating members at certain intervals on said hearth to prevent the compact from adhering to another compact.  
     
     
         36 . The apparatus of  claim 35 , wherein said separating members includes a desulfurizing agent.  
     
     
         37 . The apparatus of  claim 32 , wherein said heat-melting apparatus comprises a sloped floor for melting the compact by application of heat while tumbling or sliding the compact thereon.  
     
     
         38 . The apparatus of  claim 32 , wherein the compact is in the form of grains or aggregates and said thermal reduction apparatus comprises a mechanism for reducing the compact through the application of heat while the compact is placed on a horizontal plane.  
     
     
         39 . The apparatus of  claim 38 , wherein said thermal reduction apparatus comprises a feeding member having a horizontal plane for intermittently feeding the compact placed on said horizontal plane, a discharging member for discharging the compact from said feeding member, and a heating mechanism for heating the compact.  
     
     
         40 . The apparatus of  claim 39 , wherein said discharging member is a tilting member for making the position of said feeding member alternate between a horizontal position and a sloped position.  
     
     
         41 . The apparatus of  claim 39 , wherein said discharging member is a pushing member for pushing out the compact from said feeding member.  
     
     
         42 . The apparatus of  claim 39 , wherein an iron support is placed on said feeding member and adapted to be discharged together with the compact.  
     
     
         43 . The apparatus of  claim 39 , wherein separating members are provided on said feeding member at certain intervals to prevent the compact from adhering to another compact.  
     
     
         44 . The apparatus of  claim 43 , wherein said separating members includes a desulfurizing agent.  
     
     
         45 . The apparatus of  claim 39 , wherein said heat-melting apparatus comprises a sloped floor for melting the compact by application of heat while tumbling or sliding the compact thereon.  
     
     
         46 . The apparatus of  claim 32 , wherein the compact is in the form of grains or aggregates and said thermal reduction apparatus comprises a mechanism for reducing the compact through the application of heat while tumbling the compact.  
     
     
         47 . The apparatus of  claim 46 , wherein said thermal reduction apparatus comprises a tumbling mechanism and a thermal reduction member for heating the compact, said tumbling mechanism comprising a surface for tumbling the compact thereon and a discharging unit for discharging the compact from said surface.  
     
     
         48 . The apparatus of  claim 47 , comprising a thermal reduction-melting apparatus, comprising an integrated unit of said thermal reduction apparatus and said heat-melting apparatus, wherein said thermal reduction-melting apparatus comprises a tumbling mechanism and a mechanism for reducing and melting the compact through the application of heat, said tumbling mechanism including a sloped surface for gradually tumbling down the compact along a sloped direction and a discharging unit for discharging the compact from said sloped surface.  
     
     
         49 . The apparatus of  claim 47 , wherein said surface of tumbling is formed of the interior surface of a channel-like member.  
     
     
         50 . The apparatus of  claim 49 , wherein the interior surface of said channel-like member has an arc-shape, V-shape, or U-shape.  
     
     
         51 . The apparatus of  claim 47 , wherein said surface comprises the interior surface of a channel-like member having an arc-shape, V-shape, or U-shape and is sloped along the length of the channel-like member.  
     
     
         52 . The apparatus of  claim 32 , wherein the compact is in the form of grains or aggregates and said thermal reduction apparatus reduces the compact through the application of heat while the compact is falling downward.  
     
     
         53 . The apparatus of  claim 52 , comprising a thermal reduction-melting apparatus, comprising an integrated unit of said thermal reduction apparatus and said heat-melting apparatus, wherein said thermal reduction-melting apparatus comprises a space of falling for allowing the compact in the form of grains to fall downward and a heating member for reducing and melting the compact in the form of grains through the sequential application of heat while the compact in the form of grains is falling.  
     
     
         54 . The apparatus of  claim 53 , wherein said separator comprises a submerged weir for receiving molten slag and molten iron falling from above on one side thereof and for releasing the molten slag from one side thereof and the molten iron from the other side thereof.  
     
     
         55 . The apparatus of  claim 32 , wherein the compact is in an elongated form, and said thermal reduction apparatus reduces the compact through the application of beat while moving the compact downward in an upright position.  
     
     
         56 . The apparatus of  claim 32 , wherein the compact is in an elongated form, and said thermal reduction apparatus comprises a downward sloped surface for reducing the compact through the application of heat while moving the compact downward along said downward sloped surface.  
     
     
         57 . The apparatus of  claim 55 , wherein there is provided an apparatus for continuously forming an elongated compact on the material feed side of said thermal reduction apparatus.  
     
     
         58 . The apparatus of  claim 32 , further comprising means for feeding an iron belt operable to convey the compact thereon, the compact placed on said iron belt being subjected to reduction and melting through the application of heat.  
     
     
         59 . The apparatus of  claim 58 , wherein the compact is in the form of grains Or agglomerates, and said iron belt has edge portions and comprises walls formed at said edge portions thereof to prevent the compact from falling off said iron belt and conveys the compact thereon in a horizontal direction within said thermal reduction apparatus for reducing the compact through the application of heat.  
     
     
         60 . The apparatus of  claim 58 , wherein the compact is in an elongated form, further comprising forming means for continuously forming the compact in an elongated form and for feeding the compact in an elongated form onto said iron belt.