As a potential ore resource to produce alumina in industry, the complex symbiotic relationship between the aluminum-, silicon- and iron-bearing minerals in the high-silicon bauxite and severe desilication reactions during digestion process restrict its application. In this paper, a novel zero-waste process consisting of a roasting pretreatment and two-stage leaching was proposed to comprehensively utilize the high-silicon bauxite, and the phase transition mechanism and leaching properties of the roasting solid were systemically studied. When the roasting temperature is over 310 °C, the diaspore and kaolinite in the bauxite lose the crystal water, and gradually transform to alumina and metakaolin respectively. As the roasting temperature rises to above 950 °C, the metakaolin decomposes to an amorphous aluminosilicate phase and silica. The crystallinity of decomposed alumina and silica increases with the increase of roasting temperature and duration, but the excessive temperature and duration deteriorate the extraction property of the roasted bauxite. The optimal roasting conditions for the atmospheric-pressure leaching of silica and high-pressure leaching of alumina are 1050 °C for 30 min, and the corresponding extraction efficiencies of Al₂O₃ and SiO₂ are above 94 % and 88 % respectively. The Fe₂O₃ and Na₂O contents in the final leaching product are 55.23 % and 0.23 %, and can be directly used as iron concentrate in the ironmaking process.

作为工业生产氧化铝的潜在矿石资源，高硅铝土矿中含铝、硅、铁矿物之间复杂的共生关系以及消化过程中严重的脱硅反应限制了其应用。本文针对高硅铝土矿综合利用提出了一种焙烧预处理和两段浸出的零废新工艺，系统研究了焙烧固体的相变机理和浸出特性。当焙烧温度超过310℃时，铝土矿中的水铝石和高岭石失去结晶水，分别逐渐转变为氧化铝和偏高岭土。随着焙烧温度升至 950 °C 以上，偏高岭土分解为无定形硅铝酸盐相和二氧化硅。分解后的氧化铝和二氧化硅的结晶度随着焙烧温度和焙烧时间的增加而增加，但过高的温度和焙烧时间会降低焙烧铝土矿的提取性能。常压浸出二氧化硅和高压浸出氧化铝的最佳焙烧条件为 1050 ℃ 30 min，相应的铝提取率₂ O ₃和SiO ₂分别在94%和88%以上。最终浸出产物中Fe ₂ O ₃和Na ₂ O的含量分别为55.23%和0.23%，可直接用作炼铁过程中的铁精矿。