高硫铝土矿氧化焙烧脱硫的节能条件优化

The Optimized Energy-Saving Conditions for Desulfurization of Bauxite by Oxidizing Roasting

氧化焙烧法处理高硫铝土矿,具有操作简便、能够同时去除矿石中有机物的优点,但仍存在着能耗高以及一水硬铝石脱水造成氧化铝溶出困难等问题.本研究基于黄铁矿和一水硬铝石的热分析和恒温焙烧实验结果,发现黄铁矿脱硫与一水硬铝石脱水反应起始温度接近,但脱硫反应速率慢而脱水反应速率快,从而提出通过降低焙烧反应温度、延长反应时间来提高脱硫率、抑制脱水率的处理工艺.通过模拟样品和实际样品的焙烧条件优化实验,确定硫含量为3.8%的铝土矿最佳脱硫处理条件为：空气气氛下,焙烧温度460～470℃,焙烧时间15～20min,处理后铝土矿含硫量低于0.5%,符合拜耳法氧化铝生产工艺的要求.

Oxidizing roasting method is one of desulfurization methods for high sulfur bauxite due to its simple operation and removing organic matter,but there are still some problems such as high energy consumption and the difficulty in dissolution of alumina because of the dehydration of diaspore.The results of thermal analysis and constant temperature roasting experimental of pyrite and diaspore show that the initial temperature of pyrite desulphurization and diaspore dehydration are close to each other,while the dehydration reaction rate is faster than desulfurization.Based on these results,an energy-saving and effective desulfurization method is proposed in this study to decrease the roasting reaction temperature and prolong the reaction time to improve the desulfurization rate and inhibit the dehydration rate.According to the results of the roasting conditions optimization experiments of simulation samples and actual samples,the best desulfurization process conditions are as following：calcination on air atmosphere at 460-470 ℃ for 15-20min.The sulfur content in bauxite after treatment was less than 0.5%, which met the requirements of Bayer process.