Transport Characteristics Of Suspension-colloidal-solute Coupled Action In Tailing Leachate

In the process of transport in tailings leachate,which exists in suspended matter,colloid and solute,it is easy to have a series of complex reactions.For the purpose of studying the cause of dam break in tailings reservoir,the adsorption kinetics and isothermal adsorption characteristics of suspended matter to nano-silver colloid and solute solution were explored,studying the mutual adsorption ability.The influence of settlement was determined by the settling process of suspended matter,nano-silver colloid and solute.In order to understand the settling process of suspended matter,nano-silver colloid,solute,the sediment in the settlement test was characterized by fourier infrared spectrometer,XRD,Mastersizer 3000 for microscopic performance.For the sake of combined permeation and migration of suspended matter,colloid and solute in the drainage filtration layer was studied.Combined with the above tests,the following conclusions were drawn:（1）The pseudo-second-order kinetic model can simulate the adsorption kinetic behavior of suspended matter to calcium chloride,aluminum sulfate,nano-silver colloidal solution.According to the langmuir adsorption model,the maximum adsorption capacity of Al（III）,Ca（II）and Ag（I）is 380.40 to 444.69mg/kg,445.45 to 599.52 mg/kg,488.42 to 694.70 mg/kg,respectively.The adsorption process includes monolayer adsorption,which may contain multilayer adsorption and interaction between particles.（2）The hydrogen oxide ion in nano-silver colloidal combines with the hydrogen ion in suspension to reduce the surface charge of suspended matter,and promotes adsorption.Solute solution such as Ca²⁺,Al³⁺is easy to contact suspended matter to form unique diffusion bilayer model,which destroys the interparticle repulsion force and easily produces agglomeration with suspended matter particles.The Ca²⁺ion radius is larger than Al³⁺,it is easier to compress the nano-silver electric’s double layer and increase the possibility of agglomeration,moreover,a calcium bridge is formed to promote sedimentation.The double hydrolysis of aluminum sulfate solution and suspended matter resulted in carbon dioxide overflow,which slows down the bonding rate of nano-silver colloid with suspended matter,then the settling effect is poor.According to the data fitting,the solid concentration of the supernatant at each time is expressed by equation c=y₀+ae^（bx）,which monitors solid deposition and agglomeration.（3）When the suspended matter-colloids,suspended matter-solute pairwise coexist,the special charged property of the colloid is easy to contact and cover the surface of the suspended,thus the volume of sediment increases,and the specific surface area decreases.After sediment is dried,mineral composition does not change as same as the situation of suspended matter-calcium chloride.Aluminum sulfate is easy to react with suspended matter,which leads to the destruction of the whole structure of suspended matter,moreover,the loose particles are not easy to agglomerate,and the volume of sediment becomes smaller and the specific surface area becomes larger,moreover,the mineral composition changes,and new solid particles aluminum hydroxide exist in the sediment.When the suspended,colloid and solute coexist,the reaction of aluminum sulfate with the suspended takes precedence over the adsorption of the suspended with colloid.（4）When suspension-nano-silver colloid and suspension-nano-silver colloid-calcium chloride as leachate,the migration speed of the nano-silver particles with suspension is slower than its water flow speed,then it hinders the downward migration of leachate,causing the rate of clogging is fast.The porosity increases linearly with the depth of sand column,moreover,the surface of sand column is blocked seriously.Compared with the suspension-aluminum sulfate leachate,the solute is easily adsorbed because of chemical reaction,which slows down the speed of leachate downdard,so the ability of the leachate to penetrate to the depth is better,but the rate of clogging is slower.The porosity of sand column surface and bottom is smaller,but the clogging degree of sand column in surface is higher than that of bottom.