Dewatering of coal fines using a super absorbent polymer

403 The Journal of The South African Institute of Mining and Metallurgy JULY/AUGUST 2003 Introduction Coal preparation is used to upgrade run-ofmine coal before it is utilized by the end-user, primarily electric utility power plants. According to Fonseca1, the coal preparation process reduces the amount of noncombustible mineral impurities, acid-rain precursor sulphur-bearing minerals and hazardous trace elements, and generally produces more uniform, higher energy content fuels. Most conventional and advanced coal cleaning processes, unfortunately, involve the use of water. Dewatering of the fine, clean coal to a low moisture level (<10% w/w) is often a problem. Excessive moisture in the final product is a great concern for utility companies since various handleability problems result. Current fine coal dewatering technologies include press filters, dewatering screens, thermal drying and centrifugal dewatering, and although each of these technologies has its own particular benefits, they also have drawbacks. According to Kamall2 thermal drying is the only fully developed method that can currently be used to achieve low moisture content within product specification (approx. 9% w/w) after applying press filters or dewatering screens. Utilizing thermal methods is not the best option due to the safety hazards and high operational cost. Super absorbent polymers (SAPs) could provide a viable alternative, since these polymers are granular, highly cross-linked synthetic copolymers with excellent water-absorbing properties3. SAPs have been reported, by Dzinomwa4, to absorb water to moisture levels comparable to those resulting from thermal drying (<10%). Their ability to be regenerated by various means also makes this option highly attractive.