Abstract
The inherent composition of the produced steel, phosphorus is brought by the coke used. As coke results from the used coal, phosphorus control in the initial coal is important. Coal from Morupule Coal Mine which is supplied to the Southern African ferrochrome industry was used in this paper. Phosphorus is finely disseminated in coal and or forms part of the coal organic structure. Despite the use of coal facility at Morupule, the final product contains not less than 0.02% of phosphorus which is the maximum permissible. It is challenging to be reduced by conventional coal cleaning processes. Selective seam mining is the current implemented options at Morupule coal mine to attain the low phosphorus product but it is costly and time consuming. Hence the aim of this work to investigate the coal leaching as a primary method to reduce phosphorus content in the final product. Hydrochloric acid at a concentration of 1 Mol was used as a leaching agent for 4 hours at room temperature. 64% phosphorus removal was achieved resulting in only 0.012% residual phosphorus. To improve the rate of reaction, Microwave preprocessing was conducted in an attempt to further reduce the amount of phosphorus in the coal. The effect of phosphorus reduction using 1000 W single mode cavity was compared to that of the multimode cavity. The optimum processing parameters were found to be 2 minutes single mode microwave pretreatment and 3 hours leaching time to yield a residual phosphorus of 0.008%.
M.Tech. (Extraction Metallurgy)