碳酸盐在铝土矿溶出过程中的脱除行为

采用XRD，XRF，SEM-EDS和PSD等检测手段，系统研究了不同石灰添加量、溶出温度、晶种添加量和碳酸盐质量浓度下一水硬铝石型铝土矿高压溶出过程中铝酸钠溶液中碳酸盐含量的变化规律及其脱除机理.结果表明:铝酸钠溶液中碳酸盐质量浓度为25g·L^-1时，氧化铝溶出和碳酸盐脱除的最佳条件为:石灰添加量为11%，溶出温度为270℃，此时氧化铝的溶出率和碳酸盐的脱除率分别为72.47%和68.95%.具有板条状结构的霞石(Na₆(Al₆Si₆O₂₄)·Na₂CO₃·2H₂O)为脱除碳酸盐时的主要产物.铝酸钠溶液中碳酸盐质量浓度在25g·L^-1以下时碳酸盐更易脱除.

Removal Behavior of Carbonate in Bauxite Digestion Process

The changing rule and removal mechanism of carbonate from sodium aluminate solution with lime addition， digestion temperature， seed addition and carbonate concentration were systematically investigated by XRD， XRF， SEM-EDS and PSD methods. The results show that when the mass concentration of carbonate in sodium aluminate solution is 25g·L^-1， the optimum digestion conditions of alumina and removal conditions of carbonate were lime addition of 11% and reaction temperature of 270℃， and the corresponding digestion rate of alumina and removal rate of carbonate were 72.47% and 68.95% respectively. Cancrinite (Na₆(Al₆Si₆O₂₄)·Na₂CO₃·2H₂O) with panel structure is the main product in the carbonate removing process. Carbonate is easier to be removed from sodium aluminate solution when its concentration is lower than 25g·L^-1.