Shoppert Andrei, Loginova Irina, Napol'skikh Julia, Valeev Dmitry
Laboratory of Advanced Technologies in Non-Ferrous and Ferrous Metals Raw Materials Processing, Ural Federal University, 620002 Yekaterinburg, Russia.
Department of Non-Ferrous Metals Metallurgy, Ural Federal University, 620002 Yekaterinburg, Russia.
Materials (Basel). 2022 Feb 11;15(4):1343. doi: 10.3390/ma15041343.
Bauxite residue, also known as red mud (RM), from alumina production is the most promising technogenic material for the production of scandium (Sc) and other rare earth elements (REEs). Conveniently, RM is processed by using a strong acid (pH < 2.5), which lead to co-dissolution of iron and other undesirable major components. In this work, for the first time, the possibility of selective extraction of scandium from red mud by using highly diluted acid (pH > 4) in the presence of MgSO was shown. The effect of temperature (40-80 °C), time (0-60 min), pH (2-5), and the MgSO concentration (12-36 g L) on Sc extraction efficiency was evaluated. It was shown that Sc extraction was higher than 63% even at a pH of 4, at 80 °C, after 1 h, while more than 80% could be extracted at a pH of 2. Iron extraction reduced from 7.7 to 0.03% by increasing the pH from 2 to 4. The kinetics study using the shrinking core model (SCM) has shown that diffusion through a product layer is a rate-limiting stage of the process at high temperatures (>60 °C) and low pH (<3), whereas, at lower temperatures and higher pH values, the leaching rate is limited by diffusion through the liquid film.
铝土矿残渣，也称为赤泥（RM），来自氧化铝生产，是生产钪（Sc）和其他稀土元素（REEs）最有前景的工业源材料。方便的是，RM通过使用强酸（pH < 2.5）进行处理，这导致铁和其他不需要的主要成分共同溶解。在这项工作中，首次展示了在MgSO存在下使用高度稀释的酸（pH > 4）从赤泥中选择性提取钪的可能性。评估了温度（40 - 80°C）、时间（0 - 60分钟）、pH（2 - 5）和MgSO浓度（12 - 36 g/L）对Sc提取效率的影响。结果表明，即使在pH为4、80°C、1小时后，Sc提取率仍高于63%，而在pH为2时提取率可超过80%。通过将pH从2提高到4，铁提取率从7.7%降至0.03%。使用收缩核模型（SCM）的动力学研究表明，在高温（>60°C）和低pH（<3）下，通过产物层的扩散是该过程的限速阶段，而在较低温度和较高pH值下，浸出速率受通过液膜的扩散限制。
