Cleaning of Thar coal by froth flotation and water washing

The demand for a constant supply of energy is increasing day by day. To meet these increasing demands the natural resources must be utilized smartly. Coal can be a promising fuel due to its large reserves available in Pakistan. About 175 billion tons of coal reserves are found in Thar region of Sindh province. The major issue is the pre-processing cleaning of coal after it is mined out. A number of methods have been adopted to clean coal. Presently, cleaning of Thar coal was carried out using froth flotation and water washing techniques. Three different particle sizes (-60#, -100# and -150#) were employed to study the effect of froth flotation on ash and sulfur reduction. Experiments were carried out in laboratory flotation cell and beakers under different set of conditions (i.e., flotation with and without collector and frother and by simple water washing). Kerosene oil was used as a collector and pine oil as a frother. Characterization of raw and treated Thar coal samples was carried out by ASTM standards. The results exhibited an inverse relationship of particle size towards efficiency of the cleaning process; thus, the optimal combustible recovery was attained at -150# particle size. Furthermore, FTIR results disclosed the presence of aromatic and aliphatic structure in treated coal samples. Thermo-gravimetric analysis was also made to determine the weight loss in raw and treated samples and observed increased combustion efficiency and reactivity of Coal.