Abstract: The reductive Bayer process creates favorable conditions for the synergistic smelting of aluminum and iron. However, the high-iron red mud generated by this process generally contains impurity elements such as Al, Si, and Ti, which are detrimental to iron smelting. Isomorphous substitution easily occurs between Ti4+ and Fe3+, which leads to significant difficulties in Ti-Fe separation and becomes a major challenge hindering the utilization of high-iron red mud as a raw material for ironmaking. In this study, targeting the high-iron red mud from the reductive Bayer process provided by a certain smelting plant, based on the occurrence characteristics of impurities such as aluminum, silicon, and titanium, technical research was carried out on the selective dissolution and removal of sodium silica slag in the high-iron red mud by weak acid, as well as the reduction and transformation of titanium-bearing hematite and the coordination dissolution of titanium. Under the optimized acid dissolution conditions, aluminum and silicon in the high-iron red mud were significantly removed. The dissolution rate of Si was approximately 80%, and the dissolution rate of Al was about 70%~80%. When the acid-dissolved red mud was jointly reduced and transformed by the titanium transformation agent of sodium alkali and iron powder, the coordination dissolution rate of titanium reached 36.7%. When the acid-dissolved red mud was jointly reduced and transformed by the titanium transformation agent of sodium alkali and hydrogen, the coordination dissolution rate of titanium reached 70%~80%. Additionally, it was observed that the wuestite phase and metallic iron phase, formed after the reductive transformation of acid-leached red mud, could be further converted into the siderite phase in the potassium bicarbonate solution used for coordinated titanium leaching. This study has opened up new ideas for the separation of titanium and iron when they are of isomorphous occurrence.

Key words: reductive Bayer process, high-iron red mud, acid dissolution of sodium aluminosilicate, reduction and transformation, complexation and dissolution of titanium

摘要： 还原拜耳法为铝铁协同冶炼创造了有利条件，但该方法产生的高铁赤泥中，普遍存在不利于铁冶炼的Al, Si和Ti等杂质元素。其中Ti4+和Fe3+之间易发生类质同象置换，导致钛铁分离困难，是影响高铁赤泥用作炼铁原料的重大难题。针对上述难题，本研究以某冶炼厂还原拜耳法工艺产出的高铁赤泥为研究对象，根据铝、硅和钛等杂质的赋存形态与分布特征，开展了高铁赤泥中钠硅渣弱酸选择性溶解脱除及含钛赤铁矿还原转型-配位溶钛的技术研究。研究结果表明，在优化的弱酸溶出条件下，高铁赤泥中Al和Si杂质实现了大幅脱除，其中Si的溶出率约为80%，Al的溶出率约为70%~80%。当酸溶赤泥被钛转型剂钠碱和铁粉共同还原转型后，Ti配位溶出率达到36.7%；而利用酸溶赤泥被钛转型剂钠碱和氢气共同还原转型后，Ti配位溶出率显著提升至70%~80%。此外，酸溶赤泥经还原转型后形成的方铁矿相与金属铁相，在钛配位溶出所用的碳酸氢钾溶液中，可进一步转化为菱铁矿相。综上，本研究成果为解决钛铁类质同象赋存而难以分离的难题提供了新思路。

关键词: 还原拜耳法, 高铁赤泥, 铝硅酸钠酸溶, 还原转型, 络合溶钛