Synthetic rutile process b

Abstract

A process for recovering titanium as synthetic rutile from a titaniferous ore, for example a secondary ilmenite, includes the steps of treating the ore in a reducing atmosphere at elevated temperature above 1075° C. in the presence of a carbonaceous reductant whereby to convert the ilmenite to reduced ilmenite in which iron oxides in the ilmenite have been reduced to metallic iron, and separating out the metallic iron so as to obtain a synthetic rutile product. The carbonaceous reductant comprises a coal selected for a moisture content below 40%, a volatiles content greater than 30%, ash content below 10%, and a gasification reactivity that results in an increased rate of reduction of iron oxides and titanium species effective to achieve a TiO2 content of 90% or greater in the synthetic rutile product.

1 . A process for recovering titanium as synthetic rutile from a titaniferous ore, for example a secondary ilmenite, including the steps of:
 treating the ore in a reducing atmosphere at elevated temperature above 1075° C. in the presence of a carbonaceous reductant whereby to convert the ilmenite to reduced ilmenite in which iron oxides in the ilmenite have been reduced to metallic iron, and separating out the metallic iron so as to obtain a synthetic rutile product,   wherein said carbonaceous reductant comprises a coal selected for a moisture content below 40%, a volatiles content greater than 30%, ash content below 10%, and a gasification reactivity sufficiently high to result in an increased rate of reduction of iron oxides and titanium species effective to achieve a TiO 2  content of 90% or greater in said synthetic rutile product.   
     
     
         2 . A process according to  claim 1  wherein the elevated temperature of said treatment is in the range 1075-1200° C. 
     
     
         3 . (canceled) 
     
     
         4 . A process according to  claim 1  wherein said gasification reactivity of the coal is relatively high (as defined herein). 
     
     
         5 . A process according to  claim 1  wherein the selected coal has relatively high impurity levels of one or more ion-exchanged inorganic elements that increase the gasification rate of the coal thus improving the reducing conditions in the process and thereby increasing said rate of reduction of iron oxides and ilmenite species. 
     
     
         6 . A process according to  claim 5  wherein the acid extractable portion of said one or more ion-exchanged inorganic elements is at least 50%. 
     
     
         7 . A process according to  claim 1  wherein the selected coal has relatively high impurity levels of ion-exchanged calcium. 
     
     
         8 . A process according to  claim 1  wherein the selected coal is a sub-bituminous or lignite coal. 
     
     
         9 . A process according to  claim 8  wherein inherent moisture content of the selected coal is 20% or less, volatiles content is >40%, and ash content is <5%. 
     
     
         10 . A process according to  claim 1  further including mixing char with the ilmenite before it is delivered for said treatment step. 
     
     
         11 . A process according to  claim 1  wherein the sulphur content of the coal is less than 1% w/w, and there is no added sulphur present for most of the duration of said treatment. 
     
     
         12 . A process according to  claim 11 , wherein the sulphur content of the coal is less than 0.5%. 
     
     
         13 . A process according to  claim 11 , wherein the sulphur content of the coal is less than 0.2%. 
     
     
         14 . A process according to  claim 11  further including delivering sulphur to the ilmenite during said treatment step for removing manganese impurity as manganese sulphide, such delivery being effected only later during the duration of the reduction treatment. 
     
     
         15 . A process according to  claim 1  wherein the iron content of the ilmenite, expressed as FeO, is less than 12%. 
     
     
         16 . A process according to  claim 1  wherein free oxygen in the treatment atmosphere is no greater than 2.5%. 
     
     
         17 . A process according to  claim 1  wherein the TiO 2  content achieved in said synthetic rutile product is at least 93%. 
     
     
         18 . A process according to  claim 5  wherein the selected coal is a sub-bituminous or lignite coal. 
     
     
         19 . A process according to  claim 18  wherein inherent moisture content of the selected coal is 20% or less, volatiles content is >40%, and ash content is <5%. 
     
     
         20 . A process according to  claim 18  wherein the acid extractable portion of said one or more ion-exchanged inorganic elements is at least 50%. 
     
     
         21 . A process according to  claim 11  wherein the TiO 2  content achieved in said synthetic rutile product is at least 93%. 
     
     
         22 . A process according to  claim 5  wherein the iron content of the ilmenite, expressed as FeO, is less than 12%. 
     
     
         23 . A process according to  claim 15  wherein the TiO 2  content achieved in said synthetic rutile product is at least 93%.