Yagmurlu Bengi, Alkan Gözde, Xakalashe Buhle, Schier Claudia, Gronen Lars, Koiwa Ichiro, Dittrich Carsten, Friedrich Bernd
IME- Process Metallurgy and Metal Recycling, RWTH Aachen University, Aachen, Germany.
MEAB Chemie Technik GmbH, Aachen, Germany.
Sci Rep. 2019 Aug 14;9(1):11803. doi: 10.1038/s41598-019-48390-z.
Anticipated future demand and limited primary sources of Sc highlight the importance of secondary Sc resources such as bauxite residue (red mud). In this study, a process route starting from red mud aiming to recover Sc as a concentrate by a combination of pyrometallurgical and hydrometallurgical processes was developed. Bauxite residue was treated in an electric arc furnace (EAF) for Fe removal as well as slag conditioning with varying flux additions and various cooling conditions. 95% of iron recovery to the metal was achieved. Resulting slags were subjected to identical HO supported HSO leaching conditions at 75 °C. The effect of slag mineralogy and crystallinity on the leaching efficiencies were investigated using XRD and QEMSCAN analysis. As a result of the highly amorphous nature of acidic slags, maximum of 72% Sc leaching was obtained. For leached slags, water quenched basic slag was found to be the most promising condition resulting in an extreme Sc leaching yield of 97% and this slag was selected for the further Sc precipitation. High impurity removal rates and selective Sc separation were achieved with a triple-stage successive precipitation to synthesize a Sc concentrate. Starting from EAF treatment followed by leaching and precipitation, 85% of the initial Sc in the red mud was successfully recovered as Sc phosphate.
钪未来预期的需求以及有限的主要来源凸显了诸如铝土矿残渣（赤泥）等二次钪资源的重要性。在本研究中，开发了一种从赤泥出发的工艺路线，旨在通过火法冶金和湿法冶金相结合的方法回收钪精矿。铝土矿残渣在电弧炉（EAF）中进行处理，以去除铁并通过添加不同的熔剂和各种冷却条件来调整炉渣。实现了95%的铁回收至金属中。所得炉渣在75°C下进行相同的双氧水支持的硫酸浸出条件处理。使用XRD和QEMSCAN分析研究了炉渣矿物学和结晶度对浸出效率的影响。由于酸性炉渣具有高度非晶态的性质，钪浸出率最高可达72%。对于浸出后的炉渣，发现水淬碱性炉渣是最有前景的条件，钪浸出率高达97%，并选择该炉渣进行进一步的钪沉淀。通过三段连续沉淀实现了高杂质去除率和钪的选择性分离，从而合成了钪精矿。从电弧炉处理开始，经过浸出和沉淀，赤泥中85%的初始钪成功回收为磷酸钪。
