Research On Dewatering And Water Recycling For Bauxite Direct-flotation Tailings

Based on the studies of the composition and the chemical and physical properties of diasporic-bauxite tailings, this paper analyzed the reason of flotation tailings of bauxite which is difficult to dewater by sedimentation, and the process of water recycling of tailings was also studied.The effects of pulp pH value, pulp concentration, coagulant and flocculant on the sediment properties of tailings were studied by the sedimentation test. The results show that surface electrical property of mineral particles is the one of the important factors which has effect on tailings sedimentation. When the pH value is equal to 7, good sedimentation results for bauxite tailings can be obtained. Concentration of tailings pulp is another important factor for tailings sedimentation. In high concentration pulp, the viscosity is too big to slow the settlement of particles. Inorganic coagulants can reduce the pH value of tailings pulp, but the sedimentation results are not as well as hydrochloric acid. Considering the water recycling, the anion polyacrylamide with the molecular weight of 14 million can present the best sedimentation result at pH=7. Comparing four kinds of organic acids with hydrochloric acid, the sedimentation velocity of tailings is faster while using four organic acids instead of hydrochloric acid. Generally, P-toluene sulfuric acid is the best, glycollic acid takes the second place, sulfosalicylic acid and ascorbic acid are relatively worse.The floatation results show that water quality plays more important role in the flotation of diaspore and bauxite ore, but better results could be produced by using organic acid (PTC) as pH value regulator than using HC1.The Zeta potential and FTIR spectrum measurements show that cationic polyacrylamide can reduce the absolute value of Zeta potential of bauxite tailings. The adsorption of cationic flocculant on tailings is mostly in the form of electrostatic physical adsorption, but the adsorption of anionic polyacrylamide on kaolinite and diaspore surface is mostly in the form of hydrogen bond adsorption and it forms stronger flocculation of tailings.