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在用盐酸浸出氧化铝赤泥提取氧化钪的过程中,稀土元素镧,铈,钕也一同浸出,进入到浸出液中。研究了拜耳法赤泥盐酸浸出稀土元素镧,铈,钕的过程。研究了浸出温度、酸度、液固比和浸出时间对稀土元素浸出率的影响。研究结果表明,影响稀土浸出率的因素依次是浸出温度,盐酸浓度,配料液固比,和浸出时间。当接近沸点109℃浸出时,镧、铈、钕浸出率提高最快。盐酸酸度在4～5 mol.L-1时,浸出率升高较快,5～7 mol.L-1时,缓慢提高,当超过7 mol.L-1时,镧、铈、钕的浸出率基本不变化。当液固比为4.0时,镧、铈、钕元素的浸出率较低,仅为60%～75%之间,当液固比提高到5.0时,稀土元素的浸出率升高较快。随着浸出时间的延长,氧化稀土的浸出率从60～180 min时,缓慢提高,在180 min时达到最大值,超过180 min后,变化不大。在温度为沸点(109℃),液固比6.0,时间180 min。盐酸浓度7 mol.L-1的条件下浸出,赤泥中La,Ce,Nd的浸出率能达到95%以上。
During the extraction of scandium oxide from hydrochloric acid leaching alumina red mud, rare earth elements such as lanthanum, cerium and neodymium are also leached into the leachate. The leaching process of rare earth elements lanthanum, cerium and neodymium by Bayer process red mud hydrochloric acid was studied. The effects of leaching temperature, acidity, liquid-solid ratio and leaching time on the leaching rate of rare earth elements were studied. The results show that the factors affecting rare earth leaching rate were leaching temperature, hydrochloric acid concentration, the ratio of liquid to solid, and leaching time. When leaching near the boiling point of 109 ℃, the leaching rate of lanthanum, cerium and neodymium is the fastest. When the acidity of hydrochloric acid is in the range of 4 ~ 5 mol.L-1, the leaching rate increases rapidly and increases slowly at 5 ~ 7 mol.L-1. When the hydrochloric acid is more than 7 mol·L-1, the leaching rate of lanthanum, cerium and neodymium Rate basically unchanged. When the liquid-solid ratio is 4.0, the leaching rates of lanthanum, cerium and neodymium are low, only between 60% and 75%. When the liquid-solid ratio increases to 5.0, the leaching rate of rare earth elements increases rapidly. With the leaching time prolonging, the leaching rate of rare earth oxide slowly increased from 60 to 180 min and reached the maximum at 180 min, but little changed after more than 180 min. At the temperature of boiling point (109 ℃), liquid-solid ratio of 6.0, time 180 min. Hydrochloric acid concentration of 7 mol.L-1 leaching, red mud La, Ce, Nd leaching rate can reach more than 95%.