Extended DLVO theory applied to coal slime-water suspensions

Coal slimes are mainly composed of coal and clay particles. The interaction energies among these particles were calculated using extended DLVO (DERJAGUIN-LANDAU-VERWEY-OVERBEEK) theory and the aggregation mechanisms were analyzed based on the settling experiments for coal-kaolinite and coal-montmorillonite suspensions, respectively, under different conditions of water hardness. The results indicate that for coal-kaolinite suspensions, as the water hardness reaches 10.0 mol/L, the coal particles aggregate with each other easily, and then, the coal particles may aggregate with kaolinite particles. However, no aggregation occurs between kaolinite particles. A clay platelet network is formed in coal-montmorillonite suspensions by montmorillonite particles and coal particles are captured into the network. Coal and montmorillonite particles settle completely.