Low temperature direct reduction of metal oxides via the in situ production of reducing gas

Abstract

A continuous process for low temperature reduction of metal oxides from carbonaceous material, using in situ produced reducing gas. In particular, a method of reducing metal oxide to metal in a continuous process comprising: (a) continuously introducing composite bodies comprising low rank carbonaceous material and metal oxide containing material that are in intimate contact and in a dry mix ratio of from about 1:2 to about 1:10 to an upper region of an upright retort; (b) conveying said bodies from said upper region to a heated lower region of said retort wherein said composite bodies are exposed to increasing temperature of up to about 950° C. and wherein said composite bodies are exposed to reducing gas generated in situ for a period of from about 15 minutes to about 3 hours to thereby produce a reduced metal containing product; and (c) continuously removing the reduced metal containing product from a lower region of the retort.

1 . A method of reducing metal oxide to metal in a continuous process comprising:
 a. continuously introducing composite bodies comprising low rank carbonaceous material and metal oxide containing material that are in intimate contact and in a dry mix ratio of from about 1:2 to about 1:10 to an upper region of an upright retort;   b. conveying said bodies from said upper region to a heated lower region of said retort wherein said composite bodies are exposed to increasing temperature of up to about 950° C. and wherein said composite bodies are exposed to reducing gas generated in situ for a period of from about 15 minutes to about 3 hours to thereby produce a reduced metal containing product; and   c. continuously removing the reduced metal containing product from a lower region of the retort.   
     
     
         2 . The method according to  claim 1  wherein the composite bodies comprising low rank carbonaceous material and metal oxide are produced by mixing/attritioning particulate low rank carbonaceous material and metal oxide containing material with optional addition of water to produce a plastic mass, forming moist composite bodies and drying to produce dried composite bodies. 
     
     
         3 . The method according to  claim 2  wherein the metal oxide containing material is a metal oxide containing mineral ore or a metal oxide containing material produced as a product or by-product of an industrial process. 
     
     
         4 . The method of  claim 2  wherein the moisture content of said dried composite bodies is up to about 15% w/w. 
     
     
         5 . The method according to  claim 2  wherein the forming of moist composite bodies is by extrusion and the composite bodies are pellets. 
     
     
         6 . The method according to  claim 1  wherein the dry mix ratio of low rank carbonaceous material to metal oxide containing material is from about 1:3 to about 1:9. 
     
     
         7 . The method according to  claim 1  wherein the dry mix ratio of low rank carbonaceous material to metal oxide containing material is about 1:5. 
     
     
         8 . The method according to  claim 1  wherein the low rank carbonaceous material is lignite or sub-bituminous coal. 
     
     
         9 . The method according to  claim 1  wherein the low rank carbonaceous material is peat. 
     
     
         10 . The method according to  claim 1  wherein the metal oxide containing material comprises one or more of ferrous oxide (FeO), hematite (Fe 2 O 3 ), magnetite (Fe 3 O 4 ), chromite (FeCr 2 O 4 ), magnesiochromite (MgCr 2 O 4 ), ilmenite (FeO.TiO 2 ), manganese ore (Mn 2 O 3 ) and limonite (Fe.Ni)O(OH).H 2 O. 
     
     
         11 . The method according to  claim 1  wherein all reducing gas is atmospheric or produced in situ. 
     
     
         12 . The method according to  claim 1  wherein said composite bodies are exposed to reducing gas generated in situ for a period of from about 20 minutes to about 2 hours. 
     
     
         13 . The method according to  claim 1  wherein the reducing gas comprises gases selected from one or more of C 1 -C 10  hydrocarbon, H 2 , CO, CO 2  and H 2 O. 
     
     
         14 . The method according to  claim 13  wherein the hydrocarbon comprises C 1 -C 6  hydrocarbon. 
     
     
         15 . The method according to  claim 1  wherein metal oxide reduction is primarily H 2  gas reduction. 
     
     
         16 . The method according to  claim 1  wherein metal oxide reduction occurs within the composite bodies due to reducing gas evolved within the composite bodies. 
     
     
         17 . A reduced metal containing product produced by a method according to  claim 1 .