Study On The Evolution Mechanism Of Osmotic Characteristics Of Ionic Rare Earth Ore Bodies During Leaching

At present,in-situ leaching method is a kind of considerably ripe process used in ion-adsorption rare earth ore.The method has the advantage of simple technology,quick ore removal and low cost.In fact,there are environmental accidents such as landslip,water loss and soil erosion in the leaching process,which impact severely promotion of the method.In the leaching process,the inner structure of rare earth is affected by chemical-seepage coupling.Micro-pore structures and permeability changing affect the effects of in-situ leaching and even cause landslips.To study the relation of micro-pore structures and macroscopical permeability,the measuring permeability tests were completed in the leaching process of rare earth by permeameter.Permeability parameter variations were researched.The variation law and formation mechanism of the permeability coefficient of the sample under ion exchange condition were studied.The influences of initial permeability on seepage flow were analyzed.The conclusions were listed below:(1)Leaching solution of rare earth was water(0-17h),rare earth ion content varied at 6.5*10-4g/t.According to(3.1),it explained that reconstitution of specimens didn't react;Leaching solution of rare earth was ammonium sulfate(7-17h),there were three stages judged by ion content: initial reaction stage(7-9h),furious reaction stage(9-14h),and terminative reaction(14-17h).After furious reaction,it tended to be quiet.(2)In the leaching process,the inner structures of rare earth was controlled by chemical-seepage coupling.Seepage flow induced pores and apertures increasing.Micro-pore structure tended to be loosen.But ion exchange caused particles restructuring,and led to a smaller apertures as well as the decrease in the number of pores.Therefore,microstructure tended to be more closely.(3)Ion exchange reactions were underway with down-flow.It was corresponding with percolation theory.Under the dual effect of chemical substitution and solution seepage in the leaching process,the seepage of the leachate had a damaging effect on the microstructure of the ore body,and the chemical substitution had a certain repair effect on the microstructure.(4)Particles were moved,and effective vadose apertures increased before seepage field stabilizing,specimen permeability coefficient increased and permeability coefficient kept constant after seepage field stabilizing.In ammonium sulfate solution leaching,permeability coefficient went up before going down in the chemical-seepage coupling process.After chemical reaction,it rised up.(5)Permeability coefficient had no obvious change in the leaching process in pure water;but it went down before going up in the leaching process in ammonium sulfate,and range-ability weaken along with the permeability decreasing.Therefore,it is suggested that the rare earth ore body with poor initial permeability can be immersed in the order of "first water after ammonium sulfate solution" to achieve the optimal leaching effect.