An Investigation into the Effects of Water Quality on Coal Flotation Performance

Abstract

- In this paper, the effects of water quality on the flotation performance of bituminous coal were investigated focussing on dissolved ions. Water was synthesised to simulate process water from coal processing plants. To evaluate the effects of these ions, a series of 32 flotations tests were conducted using the synthesized process water. The ions investigated were Ca 2+ , Mg 2+ , Cl - , SO 42, Fe 2+ , NO 3-and the pH. Analysis of results from the laboratory tests revealed that the ion that has the most effect on the flotation performance is Cl. Higher concentrations of Cl - (160 to 200 mg/l) increases the % combustible recovery. The pH was observed to be directly proportional to the % combustible recovery while Ca 2+ and Fe 2+ were observed to be inversely proportional. To achieve high % combustible recoveries, the optimum conditions are 24 mg/l Ca 2+ , 39 mg/l Mg 2+ , 200 mg/l Cl - , 0 mg/l SO 42, 0.06 mg/l Fe 2+ , 40 mg/l NO 3-, and a pH of 7.92. The most significant variable that affects the % combustible recovery is the pH, followed by Cl - , NO 3-, Mg 2+ , SO 42, Fe 2+ , Ca 2+ concentrations in that order.