拜耳法高温溶出条件下黄铁矿的反应行为

李小斌，李重洋，齐天贵，周秋生，刘桂华，彭志宏

(中南大学 冶金科学与工程学院 难冶有色金属资源高效利用国家工程实验室，长沙 410083)

摘 要：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、S^2-和SO₄^2-；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S^2-和SO₄^2-形式进入溶液。

关键词：黄铁矿；铝酸钠；拜耳法；反应行为；机理；溶出

Reaction behavior of pyrite during Bayer digestion at high temperature

LI Xiao-bin, LI Chong-yang, QI Tian-gui, ZHOU Qiu-sheng, LIU Gui-hua, PENG Zhi-hong

(National Engineering Laboratory for Efficient Utilization of Refractory Nonferrous Metals Resources,
School of Metallurgical Science and Engineering, Central South University, Changsha 410083, Ch)

Abstract: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 sulfur-rich compounds. Finally, the sulfur enters into the solution in the form of S^2- and SO₄^2-.

Key words:pyrite; sodium aluminate; Bayer process; reaction behavior; mechanism; digestion