富高岭石型铝土矿化学脱硅新工艺及其机理

Novel Process and Mechanism for Chemical Desilication from Kaolinite-Rich Diasporic Bauxite

针对富高岭石型铝土矿,首次提出了采用化学脱硅的工艺路线.研究了二氧化硅平衡溶解度与氧化铝质量浓度的变化关系,以及碱液浓度、温度和脱硅时间对矿石预脱硅率的影响.结果表明,在Na2O质量浓度为230 g·L^-1的碱溶液中,90℃化学脱硅90 min,脱硅率可达70%,铝土矿的铝硅比由4.97提高到8.5以上;矿石预脱硅过程有钠硅渣的生成,导致了矿石脱硅率的降低和碱的损失;矿石中高岭石转变成钠硅渣并不会降低脱硅精矿的有效铝硅比.

For the kaolinite-rich diasporic bauxite,a process route using chemical desilication was firstly proposed.The relationship between the equilibrium solubility of silica and the mass concentration of alumina,and the effect of lye concentration,temperature and time on the chemical desiliconization ratio of ore were studied.The results showed that the desilication ratio can reach 70%and the wAl2O3/wSiO2 of bauxite increases from 4.97 to 8.5 in the alkali solution with Na2O concentration of 230g·L^-1 at 90℃for 90min.The formation of DSP reduces the pre-desilication ratio and causes the loss of alkali.However,the conversion of kaolinite to DSP does not reduce the effective wAl2O3/wSiO2 of desilicated concentrate.