Reduction of sulfur and ash contents from low-rank coal

Abstract

This research attempted to reduce sulfur and ash content for enhanced coal recovery by the froth flotation technique. Dukki district (Pakistan) coal was upgraded using a flotation technique followed by acid leaching. Tests on flotation concentrate were carried out to improve the grade of coal further. Tests were carried out to investigate and determine the effect of critical parameters like particle size, pH, and pulp density on reducing ash and sulfur content from coal. The particle size was observed to have the most significant role in coal ash and sulfur reduction, followed by the pH, and pulp density, respectively. The optimum particle size, pH, and pulp density values were 74 μm, 9 and 10%, respectively. The results from the flotation study on a laboratory scale at optimized conditions were a 54.1% increase in total carbon, a 42.12% reduction in ash, and a 38.32% reduction in sulfur. Final ash and sulphur contents in clean coal were 15.2% and 1.65%, respectively. Thus, clean coal can preferably be used in power plants and the cement industry in the country.