Study On The Behavior And Strengthening Mechanism Of Bauxite Tailings Sedimentation

Abstract:As people’s awareness of environmental protection and safety growing, more and more mining enterprises are paying attention on the technology of dry stack tailings. How to achieve the fast settling of the tailings is an effective way to realize the solid-liquid separation of the tailings. In order to solve the problem that the flotation tailings of the bauxite was very difficult to setting, diaspore and kaolinite were selected as the research object in this paper, the sedimentation behavior and strengthen measures were systematic studied by the sedimentation test of single mineral and bauxite tailings and turbidity test, the strengthen mechanism of sedimentation was discussed by Zeta potential measurements, the calculation of solution chemistry and DLVO theoretical. The main conclusions of the thesis are as follows:(1)The size of the particle and the surface static potential of the particle are the key effect factors for the settling rate of tailings. The particle size less than10microns accounts for48.98%, the zeta potential of diaspore and kaolinite are-28.14mV and-52.15mV at the original slurry pH9.29.(2)The tests of the single sedimentation indicate that the metal ions have a significant impact on the coagulation and flocculation behavior of diaspore and kaolinite; Calcium and magnesium ions can promote the coagulation of diaspore in alkaline condition; Aluminum ion can restrain the coagulation of diaspore in the acidic condition but promote it in alkaline condition; Calcium and magnesium ions with divalent as well as aluminum ion have an adverse impact on the flocculation of the kaolinite.(3)The strengthening mechanism of bauxite tailings sedimentation was systematic studied by coagulation and flocculation, and it can be concluded that metal ions which include calcium, magnesium and aluminum act on diaspore and kaolinite mainly through their hydroxyl complexes reducing the particle surface potential, the hydrolyzed polyacrylamide promotes the flocculation of the diaspore and kaolinite by the bridge linker of the polymer.(4)The results of static sedimentation test of the bauxite tailings show that it can get good sedimentation indicators under conditions that the slurry concentration is8%, the slurry is at pH7.05, the unit consumption of polyacrylamide is200g/t, the amount of polyacrylamide is0.15%, the sedimentation rate is5.58mm/min, better than before strengthening which is0.35mm/min.