| The in-situ ammonium sulfate leaching process has been widely used to extract the rare earth from the ion-absorbed rare-earth mineral in industry.Unfortunately, the problem of this process along with the excessive consumption of ammonium sulfate leading to the pollution of ammonia nitrogen containing contaminants arises. And thus, the ammonium sulfate leaching process was researched and the operation condition was optimized. In order to develop a green and high efficient leaching process, the magnesium sulfate leaching process was studied and the kinetics of leaching process was also discussed in this study.In this paper, the in-situ leaching process was simulated by column leaching process, and the relations among RE3+、NH4+、SO42-、Si O32-、Al3+、Fe3+、p H in the leaching liquor were investigated. The results showed that ions leaching order was: Si O32->RE3+>Al3+ and the mass of the impurity ion leaching order was:Al3+>Si O32->Fe3+; the decrease of p H is conducive to the leaching of rare earth; According to the relationship between RE3+ and NH4+ in the leaching liquid, rare earth leaching process can be divided into the absorption area of ammonium, the exchange area of ammonium and the excessive area of ammonium.With the leaching concentration of(NH4)2SO4 is 2%(w/w), the rare earth concentration and the peak value of rare earth concentration were very high in the leaching liquid, the leaching rate of rare earth is very high but the consumption of ammonium sulfate is lower. So the optimal ore leaching concentration of(NH4)2SO4 is 2%(w/w); Rare earth ore has a strong adsorption capacity with rare earth, the highest per kilogram of rare earth ore can adsorb5.1632 g rare earth; No seam has a strong adsorption capacity for the rare earth mother liquor that cause rare earth can not be completely leaching out. And with the increase of no seam thickness, the leaching liquor of rare earth concentrations significantly decreased, the peak value of rare earth could be delaied and reduced, the leaching rate of rare earth also be decreased, but the consumption of ammonium sulfate could be increased. therefore,the liquid injection and liquid collection should be avoided through no seam. the ammonium sulfate addition amount of liquid to solid ratio between 0.62-0.68 When the leaching liquid is inevitable to go through no seam.Magnesium sulphate mineral leaching process optimization studies showed that magnesium sulphate as a green non-ammonium mineral leaching agent can leaching rare earthore highly efficient, and the leaching rate was as high as extracting rare earth with ammonium sulfate. Compared with the ammonium sulfate, the no seam had more negative impact on magnesium sulfate leaching ore process, so the magnesium sulfate leaching ore process should be avoided flowing no seam. The magnesium sulfate concentration had great influence on the leaching of rare earth. When the concentration of magnesium sulfate was 2%, the leaching rate of rare earth had high efficiency with the lowest consumption of magnesium sulfate and the concentration of rare earth in mother liquor was high. Therefore, the optimum concentration of magnesium sulfate in leaching ore process was 2%. The results compared with ammonium sulfate mineral leaching, the concentration and peak of rare earth leaching solution with magnesium sulphate is lower. The solid ratio of RE ore leaching agent is more0.3-0.4 than ammonium sulfate mineral leaching, and the leaching curve more gently.The studied on the kinetics of magnesium sulfate leaching ion absorbed rare earth ore showed that rare earth leaching is mainly controlled by internal diffusion, and the apparent activation energy was 9.44 k J/mol, and the equations was:... |
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