Flotation with insoluble reagents. II. Effects of surface‐active reagents on the spreading of oil at coal‐water interfaces

Abstract

Abstract Conditions of agitation strongly affect the recovery of medium rank coal by flotation with oil as collector. As long as collision between coal particles and oil droplets is not prevented by repulsion of the electrical double layers, the effect of agitation is to spread the oil at the coal‐water interface. To remove ambiguities due to the properties of the frothing agent present, experiments on the effects of surface‐active materials on the ease of spreading of the oil were carried out in a special cell with no froth present. The surface‐active reagents improve the distribution of the oil because they lower the oil‐water interfacial tension. Some aromatic materials such as cresylic acid cause similar lowering without making it possible for the oil to spread as readily as when aliphatic reagents are used.