Effect of stirring time on oil agglomeration of fine coal

Flotation is widely used to process fine coal. However, problems of concentrate contamination caused by slime coating, entrapment, and entrainment have severely impeded its performance. Oil agglomeration, another physicochemical separation method, works as a substitute to solve the contamination problems. Agglomerates were prepared from coal fines using different stirring times and the ash content and combustible recovery in four size fractions: +500, 500-250, 250-125, and -125 mu m determined. The results showed that coal particles finer than 45 mu m with low ash content transformed from scattered particles to solid agglomerates. With longer stirring times, the number of large and stabilized agglomerates increased and attained equilibrium. The agglomeration process can be separated into three stages according to the degree of agglomeration at different stirring times.