Technology of extracting scandium in the comprehensive recovery of red mud-titanium white waste acid
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Abstract
In this paper, the extraction technology of scandiumis studied by the process of extraction after removal of impurities according to the property of the leaching solution of red mud-titanium white waste acid.Firstly, a certain amount of activated carbon was added into the leaching solution to remove silicon dioxide (SiO2). The removal rate of SiO2 was 96.70 % and the removal rate of scandium was 1.25 %. It shows that, most of the SiO2 is removed while the Sc3+ content is almost constant after the addition of activated carbon. The removal of SiO2 caneffectively control the gelatinization of leaching solution and facilitate the subsequent extraction process.The effect of acidity of leach solution, extractant volume fraction, phase ratio and extraction time on scandium extraction rate were examined. The results show that the optimal acidity of leaching solution after purification at 1.81 mol/L which can avoid the emulsification of organic phase and ensure high extraction rate of scandium; the extraction rate of scandium reaches equilibrium when the phase ratio is between 1/10~1/30, and the phase ratio of 1/25 is the optimal because the leaching solution is emulsificated when the phase ratio was at 1/30; the extraction rate of scandium reaches equilibrium when the extraction time is 15 min, and reaches the maximum when the extractant volume fraction is 15 % P204 + 6 % TBP. It's found that the extraction rate of scandium is 98.80 % under the optimum extraction conditions.
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