Studied On The Leaching And Separation Of Technologies Of Weathered Crust Elution-deposited Rare Earth

Weathered crust elution-deposited rare earth ore also namedore-adsorbed rare earth ore is unique in China with the characteristic ofwidespread distribution, rich reserves, low radioactivity, and full REpartitioning, easily extracted rare earth and so on. Weathered crustelution-deposited rare earth ore is applied in metallurgy, ceramic, petroleumchemical industry, nuclear industry, electronic communication, energyenvironmental protection, mew material etc. Therefore the leaching andextraction technology are always the important research content at home andabroad. The leaching and extraction technology, the leaching reactionkinetics are studied in the condition of column leaching process in thisthesis.Rare earth ore from Jingxi province Dingnan was investigated in thethesis, mixed ammonium salts as leaching reagents, weathered crustelution-deposited rare earth ore was leached in the condition of columnleaching process. The influence of concentration of reagents, liquid-solidration and leaching flow rate on the leaching rate was investigated. Thesingle factor experiment was planned to study the experiment, the optimumleaching condition were obtained: concentration of leaching reagent,liquid-solid ration and leaching flow rate are mixed ammonium salt(NH4NO3:(NH4)2SO4=7:3),2.0%，0.5:1,0.5mL/min,respectively. Theleaching rate of RE is98.10%under the optimum conditions.The kinetics of leaching RE from weathered crust elution-depositedrare earth ore using laboratory-scale column was investigated. The effects ofconcentration of leaching reagent and particle size on the leaching rate weredetermined. The results show that the leaching process can be fit to theshrinking core model, the kinetic equation is determined to be1-2/3η-(1-η)2/3=7.126×10-4C0.3038R0.1942t. Crystalline mixed rare earth carbonate was prepared by co-precipitationmethod using weathered crust elution-deposited rare earth leaching solutionas the material and ammonium bicarbonate as the precipitation agentrespectively in this thesis. The effects of W[NH4HCO3]/W[REO] ratio,temperature, stirring time, aging time on forming crystalline mixed rareearth carbonate were studied，the results showed that W[NH4HCO3]/W[REO]2.0, temperature25~30℃, stirring time0.5~2.5h, aging time than12h.Spherical Crystal rare earth carbonate was characterized by X-raydiffraction, IR and SEM analysis.