Abstract: The leaching behavior of diaspore bauxite in KOH sub-molten was investigated. The effects of reaction temperature, mass ratio of alkali to ore, initial KOH solution concentration, reaction time and CaO addition were examined. The results indicate that the recovery rate of Al2O3 can reach 81.4% and mass ratio of Al2O3 to SiO2 of the red mud decreases to 1.06 under the optimum conditions of reaction temperature at 220℃, mass ratio of alkali to ore at 1.5, initial KOH solution concentration of 50%(w) and reaction time for 1h. The XRD analysis shows that Si exists in the form of KAlSiO4 in the red mud. Further study implies that CaO addition is not beneficial to the leaching process. A further step for extraction of K2O and Al2O3 in the red mud achieves good results with 0.61% of K2O, 8.09% of Al2O3 in the final red mud and 90.7% of Al2O3 overall leaching rate.

Key words: diaspore bauxite, sub-molten salt, KOH, leaching, Al2O3, K2O

摘要： 采用KOH亚熔盐介质溶出中低品位一水硬铝石型铝土矿，考察了反应温度、碱矿比、初始KOH溶液浓度、反应时间及添加CaO对溶出后赤泥化学成分和物相的影响. 结果表明，在反应温度220℃、碱矿质量比1.5、初始KOH溶液浓度50%(w)、反应时间1 h的条件下，Al2O3回收率可达81.4%，赤泥的铝硅质量比降至1.06，赤泥中硅主要以KAlSiO4形式存在. 溶出过程中添加CaO不能提高Al2O3溶出率. 进一步回收溶出后赤泥中的K2O和Al2O3，终赤泥中K2O含量降至0.61%，Al2O3含量降至8.09%，Al2O3总回收率可达90.7%.

关键词: 一水硬铝石, 亚熔盐法, KOH, 溶出, Al2O3, K2O