Abstract: The resource utilization of red mud is of crucial importance for the sustainable development of the alumina metallurgical industry, and it has also been a major challenge that has long constrained the progress of aluminum metallurgical processes. The breakthrough of the reductive Bayer process has dramatically improved the magnetic separation of iron from red mud and allowed the production of high-iron red mud, which has built the foundation for the co-metallurgy of Fe metal and alumina. However, there are harmful impurities such as Al, Si, and Ti in the high-iron red mud produced from the reductive Bayer process, which have adverse effects on iron smelting. What's more, Fe and Ti are highly isomorphism replaced. This makes it difficult to separate titanium from iron in red mud. This study used high-iron red mud as the raw material and characterized its physicochemical properties. The removal of Al and Si from the red mud by alkali leaching was studied based on the solubility of sodium aluminosilicate in an alkali solution. Under the optimized conditions, their removal was satisfactory; the Si content in the leached red mud was less than 0.1wt%, and the Al content was about 0.21wt%. The occurrence of the stubborn phases of calcium aluminosilicate and alumogoethit determines the leaching conditions for Al and Si. Using the principle of complexation dissolution of Ti, researched the complexation dissolving of titanium from the alkali-hydrothermal treated red mud. The results showed that the mixed system of H2O2, ammonia, and citric acid was capable of complexation dissolving amorphous metatitanic acid, and 21% titanium in the alkali-treated red mud can be complexation dissolved. However, after the alkaline leaching process, a significant portion of titanium in red mud was not yet in a favorable form for complexation dissolution. More future work on the regulation of titanium form and complexation medium is needed.

Key words: reductive Bayer process, high-iron red mud, co-metallurgy of iron and alumina, alkali dissolving of Al and Si, complexation dissolution of Ti

摘要： 赤泥的资源化利用是铝冶炼行业在可持续发展道路上必须面对的挑战。还原拜耳法的突破极大提高了赤泥中铁的磁选性能，可获得高铁赤泥，奠定了铁铝协同冶炼的基础。但还原拜耳法高铁赤泥中仍存在不利于铁冶炼的Al, Si, Ti等杂质，且钛与铁易类质同象置换赋存。本研究针对某冶炼厂提供的高铁赤泥，在物化性质系统表征的基础上，基于铝硅酸钠在碱介质中的溶解度，开展了赤泥碱水热脱铝硅的研究，在优化条件下，脱除高铁赤泥中铝硅的效果理想，赤泥中Si含量低于0.1wt%，Al含量约为0.21wt%，铝硅脱除条件的确定与铝硅赋存的难分解物相(如铝硅酸钙、铝针铁矿)等相关。利用钛络合溶解的原理对碱水热处理后的赤泥进行了钛络合溶出研究，结果表明，双氧水、氨水和柠檬酸的混合体系对无定形偏钛酸具有良好的络合溶出效果，用该混合体系可将碱水热处理后高铁赤泥中21%的钛络合溶出。但碱水热处理后赤泥中的钛尚不是有利于络合溶出的赋存形态，后续仍需从钛赋存形态调控、钛络合体系优化上获取突破。

关键词: 还原拜耳法, 高铁赤泥, 铁铝协同冶炼, 铝硅碱溶, 络合溶钛