Effect of Dextrin on the Adsorption Behavior and Surface Characteristics of Sub-Bituminous Coal and Silica

Dextrin is a derivative of starch produced by partial thermal degradation under acidic conditions, which is usually used as a depressant in the mineral processing industry. Dextrin can also effectively depress coal particles in the reverse flotation process. To study the effect of dextrin on the flotation behavior of both coal and gangue mineral in coal reverse flotation, this research compared the adsorption behavior difference between sub-bituminous coal and silica as well as the surface property change of both sub-bituminous coal and silica after being treated by dextrin. The result illustrates that the adsorbing capacity of sub-bituminous coal on dextrin is much higher than that of silica under different initial concentrations and different interaction times. The isoelectric points of both sub-bituminous coal and silica increase after being treated by dextrin. But the increasing ζ-potential value of silica is larger than that of sub-bituminous coal. Dextrin could enhance the hydrophilicity of sub-bituminous coal and weaken the hydrophilicity of silica slightly according to the result of surface wetting rate tests. Reverse flotation using dextrin as a depressant indicates that good performance could be obtained with the addition of dextrin. Larger dextrin dosage might deteriorate silica flotation slightly.