拜耳法高温溶出条件下黄铁矿的反应行为

Reaction behavior of pyrite during Bayer digestion at high temperature

在对黄铁矿与铝酸钠溶液反应热力学分析的基础上,利用接触角、X射线衍射、红外光谱和SEM-EDS等分析手段研究溶出温度和铝酸钠溶液组成对黄铁矿反应行为的影响,并探讨黄铁矿的分解过程。结果表明,黄铁矿的反应速度随溶液温度及游离碱浓度的升高而加快,最终产物主要为Fe2O3、S2-和SO42-;拜耳法溶出条件下,反应1 h黄铁矿中硫溶出率高达90%;反应初始阶段黄铁矿表面的Fe2+优先与溶液中的OH-结合生成铁羟基化合物从表面脱落,导致富硫层的形成,随着反应的进行,硫最终以S2-和SO42-形式进入溶液。

Based on the thermodynamic analysis of the reaction between pyrite and sodium aluminate solution, the effects of digestion temperature and composition of the sodium aluminate solution on the reaction behavior of pyrite were investigated by the analysis of contact angle, X-ray diffraction, infrared spectrum and scanning electron microscope- energy dispersive spectrum. The decomposition process of pyrite was also discussed. The results show that the reaction rate of pyrite increases with the increase of the temperature and the free caustics concentration in aluninate solution to produce Fe2O3, S^2- and SO4^2- as the main final products. The sulfur dissolution percentage reaches above 90% after reaction of 1 h under the Bayer process. The iron-hydroxyl complexes are generated firstly by the reaction of OH- of sodium aluminate solution and Fe2＋ of the pyrite surface, then the complexes detach from the surface of pyrite, which leads to a layer of sulfiar-rich compounds. Finally, the sulfur enters into the solution in the form of S^2- and SO4^2-.