Process for the manufacture of ferrochrome

Abstract

Process for the manufacture of ferrochrome alloy comprising the steps of providing a pelletising feed, wherein the pelletising feed comprises chromite ore and silicon carbide as the only carbonaceous material and the only reducing agent; pelletising the pelletising feed to obtain pellets; sintering the pellets to obtain sintered pellets; mixing the sintered pellets with external reducing agent to obtain smelting feed; and smelting the smelting feed.

1 . A process for the manufacture of ferrochrome alloy comprising the steps
 a) providing a pelletising feed, wherein the pelletising feed comprises
 chromite ore and 
 silicon carbide as the only carbonaceous material and the only reducing agent; 
   b) pelletising the pelletising feed to obtain pellets;   c) sintering the pellets to obtain sintered pellets;   d) mixing the sintered pellets with external reducing agent to obtain smelting feed; and   e) smelting the smelting feed.   
     
     
         2 . The process according to  claim 1 , wherein the pelletising feed further comprises a binding agent. 
     
     
         3 . The process according to  claim 1 , wherein the pelletising feed contains 4-20 wt-% silicon carbide. 
     
     
         4 . The process according to  claim 1 , wherein chromite ore is the only metal ore present. 
     
     
         5 . The process according to  claim 1 , wherein the chromite ore and the silicon carbide in the pelletising feed have a particle size distribution of 60-90% below 200 mesh. 
     
     
         6 . The process according to  claim 1 , wherein the particle size of the pellets is 8-16 mm. 
     
     
         7 . The process according to  claim 1 , wherein the pellets are in the form of green pellets. 
     
     
         8 . The process according to  claim 7 , wherein the green pellets have a moisture content of 7-16 wt-% 
     
     
         9 . The process according to  claim 7 , wherein the green pellets have a compressive strength of 1-3 kg/pellet. 
     
     
         10 . The process according to  claim 1 , wherein the sintered pellets contain ≧10% residual carbon. 
     
     
         11 . The process according  claim 1 , wherein the sintered pellets contain ≧10% residual silicon carbide. 
     
     
         12 . The process according to  claim 1 , wherein the total porosity of the sintered pellets is 15-55 vol-%. 
     
     
         13 . The process according to  claim 1 , wherein the compressive strength of the sintered pellets is 200 kg/pellet expressed as F 12mm . 
     
     
         14 . The process according to  claim 1 , wherein the sintered pellets are characterized by a metallization of chrome of <5%. 
     
     
         15 . A ferrochrome alloy obtainable by the process of:
 a) providing a pelletising feed, wherein the pelletising feed comprises
 chromite ore and 
 silicon carbide as the only carbonaceous material and the only reducing agent; 
   b) pelletising the pelletising feed to obtain pellets;   c) sintering the pellets to obtain sintered pellets;   d) mixing the sintered pellets with external reducing agent to obtain smelting feed; and   e) smelting the smelting feed.   
     
     
         16 . The alloy according to  claim 15 , wherein the pelletising feed further comprises a binding agent. 
     
     
         17 . The alloy according to  claim 15 , wherein the pelletising feed contains 4-20 wt-% silicon carbide. 
     
     
         18 . The alloy according to  claim 15 , wherein chromite ore is the only metal ore present. 
     
     
         19 . The alloy according to  claim 15 , wherein the chromite ore and the silicon carbide in the pelletising feed have a particle size distribution of 60-90% below 200 mesh. 
     
     
         20 . The alloy according to  claim 15 , wherein the particle size of the pellets is 8-16 mm.