Impurities Control Technology And Hydrodynamics Study On Weathered Crust Elution-deposited Rare Earth Ore

Weathered crust elution-deposited rare earth （RE） ore which only exist in China hasthe characteristic of wide distribution, low radioactivity, rich reserves, full REpartitioning, easily extracted rare earth and so on. Weathered crust elution-deposited rareearth ore is applied in variety of areas. The main research content concentrat on the wayof leaching technique of RE and precipitation technique of RE at home and abroad. Theimpurities control technology, preparation of crystalline rare earth carbonate and theleaching hydrodynamic are studied by spraying leaching in this thesis.Chemical composition of this rare earth ore was measured by chemical titration. Thespecific content of each chemical composition was received, then, primary analysis ofimpurity ions in leaching solution. Respectively, the content of chemical compositionobtained by experiment were:REO is0.1146%, SiO2is0.1146%, Al2O3is0.1146%,Fe2O3is0.1146%, CaO is0.1146%and other is0.1146%. Aluminum ion would be theupper most impurity ion as the leaching ion.The kinetics of impurities control method during leaching weathered crustelution-deposited rare earth ore using laboratory-scale column was investigated,decreased the content of aluminum ion in leaching solution. The effects of inhibitor types,inhibitory dosage and pH value of the leachate on the inhibited rate of aluminum werestudied. The results showed that liquid-solid ration of0.5, concentration of leachingreagent used2%mixed ammonium salt （NH4NO3:（NH4）2SO4=7:3）, the mass fraction ofinhibitor is0.05%, pH value of the leachate was5.5. It can ensure the purity of rare earthand the inhibited rate of aluminum,93.85%and92.5%, respectively.Raw material was RE dip solution which obtained by impurities control technology.Crystalline mixed rare earth carbonate was prepared by the solution of ammoniumbicarbonate. A investigation on the effect of amount of aluminum,W[NH4HCO3]/W[REO], temperature, stirring time and aging time on precipitation rate of rare earth was implemented. Meanwhile, the precipitation of RE carbonate wasanalysised by X-ray diffraction and IR. The result showed that RE carbonate which hadperfect cry stalline structure could be obtained by RE dip solution obtained by impuritiescontrol technology.The leaching process of weathered crust elution-deposited rare earth ore werestudied from the angle of water dynamics, got the hydrodynamics equation. The theorysupport was provided to improve the leaching efficiency. The effect of extraction type,extraction concentration, clay partical size and porosity on permeability was studiedwhen fixed low-pressure differential was given on the ore deposit. The effect oflow-pressure differential on the leaching rate of rare earth when low-pressure differentialwas changed. The experimental results showed that2%leaching reagent of mixedammonium salt could not only improve the effect of leaching from the angle oftechnology, but also improve the permeability from the angle of hydrodynamics whenlow-pressure differential was fixed. Meanwhile, permeability increased with the particalsize increaseed when porosity was fixed. The hydrodynamics equation was got by linearfitting, k（mm²）=7.55210^-5d^0.993φ^0.68441. The the leaching rate of rare earth was increasedwhen low-pressure differential was4.95Pa.