Froth flotation of refuse coal fines and process optimization using 2D surface plots

Refuse coal fines of size <500 µm was collected from a metallurgical coal preparation plant located in the eastern coalfield region of India. The coal was beneficiated using froth flotation technique to recover clean coal with ash content of about 20% with the highest possible yield. Diesel oil as collector and pine oil as frother were used. Box-Behnken statistical design was followed for analyzing the performance at varying pulp density, collector and frother dosage. Results were discussed using 2D surface plots. Response function predictions determined by the regression analysis show coefficient of correlation (R 2) for yield and the ash content as 0.72 and 0.86, respectively. The highest yield of 45.79% is obtained at pulp density 10%, collector dose 2 kg/t and frother dose 1.5 kg/t. The lowest ash content of 18.9% is obtained at pulp density 10%, collector dose 1 kg/t and frother dose 1 kg/t.