Optimization Research On The Extraction Process Of Low Grade Ionic Rare Earth Ore

The ionic rare earth ore of our country has been overload mined for a long time, the richerand more accessible deposits of this rare earth resource got mined in priority gradually, whichmade this resource deplete increasingly, and difficulty of extracting go from bad to worse. Inthe process of extracting the low grade ionic rare earth ore, with the low leaching rate, seriousleaching tailing, high impurity content but low concentration of rare earth ion in leachingsolution and difficult formation of crystalline carbonate rare earth, which made the resourcecan’t be used effectively. In order to solve these problems, this paper select the ionic rareearth ore from Longnan as research subjects, study and optimize its extraction process, andprovide guidance for developing and utilizing this mineral resources effectively.Firstly, this paper studied and optimized the leaching process of the low grade ionic rareearth ore, and the results showed that: the capacity of different electrolyte cation exchangingthe rare earth ions was on the order of NH4+>K+>Na+; When the Leaching agentconcentration was higher or the flow rate was slower, the leaching rate would be higher; Butwhen the leaching solution pH value was too high or too low, or the moisture content of oreand ore loading level was too high, or the grain size was too small, all these would affect theleaching efficiency of rare earth, and the rare earth leaching rate. The most optimizedparameters for the leaching process was determined: raw water rate was about5%, oreloading height was about105mm, the mass concentration of ammonium sulfate was4%(pH=5.8), leaching liquid-solid ratio was0.8:1, extraction rate was0.49mL/min, the latetop water liquid solid leaching ratio was0.05:1, the leaching solution can be obtained withleaching rate of93.88%and concentration of1.61g/L; Analysising the infrared spectrumleaching residue, we can know that after the role of rare earth and leaching agent, it didn’tproduce new substances, but ion exchange, and the crystal structure of the rare earth orewasn’t changed. With the low ammonium sulfate concentration and natural pH conditions, thecost of reagents will be saved; the leaching rate of rare earth was high, and the leachingsolution was obtained with high concentration of rare earth and low content of impuritiesexcept Al3+, thus we reach the goal of optimizing the leaching process of low grade ionic rareearth ore.In order to reduce the impurity aluminum ion content in the leaching solution, the lowgrade of ion type rare earth ore leaching liquid impurity removal process was studied, results showed that: removing aluminum from yttrium chloride solution by neutralization method,sodium acetate, sodium sulfide, ammonia and ammonium bicarbonate were all not as good asLZ in removing aluminum. Adjusting the system’s pH value with5.00could make thealuminum removal rate reach reach to97.6%and rare earth loss rate4%. The effect wasobvious; Then removing aluminum from the actual rare earth leaching solution, the aluminumremoval effect was LZ> ammonium hydroxide> ammonium hydrogen carbonate. Using LZas the aluminum removal reagent, regulating system’s pH value5.00, the removal rate ofaluminum and rare earth loss rate were93.6%and4.7%, respectively. And LZ is non-toxic,harmless to the environment, so the LZ can be used as aluminum removal agent to ionic rareearth ore leaching liquid, but it needs further exploration before it’s applied to actualproduction.By studying the process of precipitation and crystallization of low grade ionic rare earthore leaching solution, the results showed that: aluminum ions would not only increase theconsumption of precipitant, reduce the rate of precipitation of rare earth, but also notconducive to the formation of crystalline rare earth carbonates, and would affect the purity ofrare earth products ultimately. So it must be removed before precipitating rare earth; Usingammonium bicarbonate as precipitant, under the conditions of room temperature, ammoniumbicarbonate concentration was1.83mol/L,[NH4HCO3]/[RE3+](molar ratio) was4.5:1, thestirring time was30minutes, the aging time was6h, the rare earth’s precipitation rate was97.17%; Analysis the scanning electron microscopy, XRD and infrared spectrum ofprecipitate, we could see that the rare earth carbonate obtained was rare earth carbonate. Thecrystal type of the rare earth carbonate was good, which had large particles and high rareprecipitation rate. It needed small amount of precipitant, and the time of stirring and agingwas short, then production efficiency of the precipitation and crystallization process wasincreased, and achieved the purpose of optimizing the process of precipitation andcrystallization of low grade ionic rare earth ore leaching solution.