【摘要】 拜耳法生产氧化铝的过程中,碱耗的主要原因是因为有钠硅渣的生成,碱耗可以用赤泥钠硅比(N/S)表征。通过对钠硅渣和水化石榴石反应行为的热力学分析,发现高饱和系数(x>1)的水化石榴石不易被苛性碱分解,低饱和系数的水化石榴石易被分解而转化为钠硅渣,且钠硅渣也可以转化为水化石榴石,而在Na2CO3溶液中,任何形式的水化石榴石均能被分解生成钠硅渣。实验研究结果表明,不同矿区的铝土矿对赤泥N/S影响不明显,母液中Na2CO3浓度升高、石灰加入量降低、母液中碱浓度降低均会导致赤泥N/S升高,引起碱耗增大。因此,降低母液中Na2CO3浓度、提高石灰添加量将明显有利于赤泥N/S的降低。更多还原

【Abstract】 In the process of alumina production by Bayer process,the loss of soda is mainly caused by the formation of sodium hydrate alumino-silicate.Based on the thermodynamic analysis of the reaction law between sodium hydrate alumino-silicate and hydrogarnet,it is found that hydrogarnet with more amount of SiO₂（x>1） can not be decomposed by caustic solution easily,while hydrogarnet with x<0.5 can be decomposed into sodium hydrate alumino-silicate,and sodium hydrate alumino-silicate can also be transformed into hydrogarnet with the addition of CaO.But in sodium carbonate solution,any form of hydrogarnet can be decomposed into sodium hydrate alumino-silicate.Experimental results show that bauxite in different areas has little influence on the loss of soda,while more concentration of Na₂CO₃ or lower concentration of Na₂O in spent solution,or worse quality of limes will enhance N/S in red mud,and cause more loss of soda.Therefore,decreasing the concentration of Na₂CO₃ or obtaining better quality of limes will reduce N/S.更多还原