Experimental Study On Self-weight Drainage Combined With Quicklime Solidification Treatment Of Bauxite Tailings

Based on the practical problems of tailings pond and in response to the government’s policy call for vigorous control of tailings pond,this paper takes the bauxite tailings pond in Western Guangxi as the research background,takes the bauxite tailings slurry with high water content as the research object,studies the sedimentation characteristics of bauxite tailings slurry,and takes accelerating the consolidation of bauxite tailings slurry as the research goal,a set of solutions is put forward,which first mix sand to improve the properties of surface tailings slurry,then use self-weight drainage to consolidate by inserting drainage pipes,and finally combine with quicklime solidification treatment.In view of the proposed treatment scheme and the problems to be solved,the specific implementation parameters are determined through the design of relevant model tests.On this basis,two sets of models of step-by-step sand-adding stacking and step-by-step stacking are designed,and the experimental study of treatment schemes is carried out.The changes of step-by-step stacking deposition,selfweight drainage consolidation and quicklime solidification reaction process of bauxite tailings slurry are compared and analyzed,and the concrete effect of the scheme implementation is further verified.The main conclusions are as follows:(1)The lower the slurry concentration of bauxite tailings,the greater the slurry-water interface decline rate,but with the increase of settling time,the decline rate gradually decreases.The height of mud-water interface after sedimentation stabilization is closely related to mud content,but not directly related to mud concentration.With the increase of slurry concentration,the slurry water separation ratio increases gradually.After the sedimentation is close to stability,the slurry water separation ratio increases exponentially with the increase of slurry concentration.(2)The average water content of sediment mud formed after the separation of bauxite tailings mud water is basically in the range of 80%～110%.The general trend is that the higher the mud concentration,the lower the average water content of sediment mud.With the increase of deposition time,the water content in sediment mud is gradually squeezed out,and the average water content decreases accordingly.(3)Physical parameters such as water content,density,void ratio,permeability coefficient,compressibility coefficient and volumetric compressibility coefficient of tailings slurry formed by successive stacking of bauxite tailings slurry deposit vary in varying degrees along the depth direction.There are complex relationships among physical parameters,among which water content affects other physical parameters.The effect is significant.(4)After simulating the drainage period of bauxite tailings reservoir and the natural evaporation process of part of the non-accumulation reservoir surface after drainage,the water content of bauxite tailings sludge deposited at the bottom of the sedimentation column model device is basically in the range of 49.5%～85.0%along the depth direction,the density is in the range of 1.7-2.1g/cm3,the void ratio is in the range of 0.979-1.994,the permeability coefficient is in the range of 0.629-1.615,and the compressibility coefficient is in the range of 0 The volume compression coefficient is in the range of 0.295-0.690.(5)The specific parameters for determining the properties of the improved bauxite tailings slurry with sand are as follows:the size of Sand-Mixed tailings is 2.0 mm-5.0 mm,and the ratio of Sand-Mixed bauxite tailings is 20%.The optimum horizontal influence range of self-weight drainage consolidation of bauxite tailings is determined to be 400 mm,i.e.8 times the diameter of drainage pipe.Considering that the actual diameter of drainage pipe used in bauxite tailings reservoir is between 150 mm and 300 mm,the horizontal influence range is roughly within 1.2 m to 2.4 m in diameter.The influence range of quicklime solidification after self-weight drainage consolidation of bauxite tailings is determined to be less than 400 mm in diameter.In order to expand the influence range of quicklime solidification treatment,it is suggested that quicklime be used to treat bauxite tailings sludge in the future and mix the two evenly.The best time to solidify bauxite tailings with quicklime is when the water content of bauxite tailings mud is in the range of 60%～70%.(6)The experimental results of the treatment scheme are good.After treatment,the water content of bauxite tailings mud is obviously reduced,and the shear strength is significantly improved.The solidification goal is achieved,which verifies the feasibility of the scheme.The step-by-step sanding treatment has a great influence on the self-weight drainage consolidation process of bauxite tailings slime,which accelerates the drainage consolidation,further reduces the water content of bauxite tailings slime,and has a certain enhancement effect on the shear strength of bauxite tailings slime during the lime solidification reaction process.