Abstract: The dealkalization of red mud from sub-molten salt process under atmospheric pressure and low temperature was investigated. The effects of temperature, CaO addition, Na2O concentration of solution and time on the process were examined. The experimental results indicated that the content of Na2O in the final red mud decreased with the increase of CaO addition, reaction temperature and reaction time, but not so as to the initial concentration of Na2O in the NaOH solution, and it could be as low as 1.41% while mass ratio of Na2O to SiO2 was decreased to 0.07 when dealkalizing in 60 g/L Na2O solution with mass ratio of CaO to red mud 0.22 at 95℃ for 10 h. After leaching under the above conditions, the new phase of calcium silicate formed, and the morphology of the red mud changed from rod-like crystals to fluffy agglomerate with flakes.

Key words: sub-molten salt, red mud, normal pressure, dealkalization, sodium oxid

摘要： 研究了在低温常压下亚熔盐法处理铝土矿所得赤泥的脱碱过程，考察了反应温度、CaO添加量、初始溶液Na2O浓度及反应时间等因素对反应过程的影响. 结果表明，随CaO用量增加、反应温度提高和反应时间延长，终赤泥中Na2O含量降低，初始碱浓度过高或过低都不利于Na2O溶出. 在95℃、NaOH溶液/干赤泥质量比6、CaO/原赤泥质量比0.22、初始溶液Na2O浓度60 g/L、反应时间10 h的条件下，终赤泥中Na2O含量可降至1.41%，钠/硅质量比为0.07. 反应后生成了硅酸钙相，赤泥由棒状晶体转变成了绒球状的薄片聚集体.

关键词: 亚熔盐, 赤泥, 常压, 脱碱, 氧化钠