| Ionic rare earth mineral are rich in medium and heavy rare earth elements, which are supporting elements of high-tech industries. Due to the characteristics such as easy to mine, rich in species, good economic returns, ionic rare earth mine become rare and precious natural mineral resources among the world’s rare earth industry. Against ammonia pollution problems that exist in most ion-type rare earth separation plants, our group explored a "P507-N235-kerosene(kerosene-cyclohexane) extraction and separation of rare earth" process to reach the near-zero emissions of ammonia. As a part of the series research, the systematic experimental study of stripping to the loaded organic phase and subsequent precipitation process were conducted to obtain the optimal conditions of the efficient recovery of rare earth loaded in organic phase and preparation of large size rare earth compound.The study of stripping precipitation was conducted on P507-N235-Kerosene (volume ratio was25:30:45) loaded rare earth system with the acidic oxalic solution as stripping agent. The effect of stripping acidity, phase ratio and the concentration of oxalic acid on the stripping precipitation was studied. The results show that in the absence of hydrochloric acid and only added oxalic acid, the rare earth loaded in the P507-N235-kerosene can be stripped but the stripping sedimentation rate was less than80%. The best stripping precipitation effects were obtained under the condition that the concentration of hydrochloric acid was0.40mol·L-1, phase ratio (O/A) was1:1, the concentration of oxalic acid was120%. The stripping sedimentation reached95%. The application of stirring and seed adding is conductive to the growth of grain. The particle size under the opitmal parameters can reach25μ.m.The study of stripping was conducted on P507-N235-Kerosene-cyclohexane (volume ratio was25:30:22.5:22.5) loaded rare earth system with the hydrochloric acid as stripping agent. The effect of mixing oscillation time, stripping acidity, phase ratio and the concentration of loaded organic phase on the stripping rate of rare earth was studied. Then the parameters of precipitation temperature, stirring speed, concentration of oxalic acid, aging time were studied in the subsequent precipitation experiment. The results of stripping with hydrochloric acid showed that it was easier to strip from the P507-N235-kerosene-cyclohexane system. The effects of phase stratify were fine during the stripping process. The rare earth concentration contained in the loaded organic phase had little influence on the process of stripping, the optimum conditions of stripping at room temperature was as following:the oscillation time was15minutes, phase ratio was1:1, the acidity was about3mol-L·-1, its single-stage stripping rate can reach more than98%, the phase stratified completely after a minute or so. The recycling of the organic phase showed: After stripping, the organic phase can still be used to extract neodymium carbonate, neodymium hydroxide and other rare-earth compounds, the extraction capacity could arrive0.15mol-L"1. The results of precipitation experiment with oxalic acid showed: the precipitation rate could reach99%when precipitate the stripping solution with hydrochloric acid of115%of the theoretical concentration of oxalic acid. The aging time had the greatest effect on the precipitation particle size, the amount of oxalate precipitation also had a great impact on the precipitation particle size, the stirring speed had a certain impact on the precipitation particle size, the precipitation temperature had a relatively small impact on the precipitation particle size. Larger particles of rare earth oxide precursor D50with the size of55.88μm was obtained under the following condition:the aging time was30h, the amount of oxalic acid was120%of the theoretical amount. |
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