高铁三水铝石型铝土矿在铝酸钠溶液中的溶出过程

Leaching Performance of High Iron Gibbsite-type Bauxite in Sodium Aluminate Solution

在对某高铁三水铝石型铝土矿物相分析基础上,研究了其在不加钙的铝酸钠溶液中的溶出行为,考察了溶出液碱浓度、溶出温度和溶出时间对氧化铝溶出率的影响.结果表明,矿中Gibbsite形态的铝约占总铝量的70%,且嵌布于赤铁矿中;优化的溶出条件为,分子比3.0的铝酸钠溶液Na2O浓度为150 g/L、温度100℃、时间15 min,此时原矿中Al2O3溶出率达72%.该矿在低温低碱条件下的溶出过程受内扩散控制,计算的表观活化能为61.78 kJ/mol,溶出速率控制模式与表观活化能理论值不同可能与扩散形式相关.

Based on the mineralogical characteristics of high iron gibbsite-type bauxite ore from Guangxi, its leaching performance in sodium aluminate solution without addition of calcium-bearing compound was studied, and the effects of caustic concentration, reaction temperature and reaction time on Al2O3 leaching rate were examined. The results showed that 70% of aluminum in the ore mainly existed in the form of gibbsite, being conjoint with hematite. The optimum leaching conditions of gibbsite were obtained as follows： Na2O concentration in sodium aluminate solution 150 g/L, molar ratio 3.0, temperature 100 ℃ and time 15 min. Under the conditions, the leaching rate of Al2O3 reached 72%. The leaching kinetic results of bauxite under the conditions of low temperature and low alkali concentration showed that the leaching process was controlled by internal diffusion, and the calculated apparent activation energy was 61.78 kJ/mol. The inconsistency between the control mode and the apparent activation energy value might be due to the diffusion mode.