硅酸锌加压硫酸浸出的热力学分析与实验研究

计算绘制了Zn-Si-H2O系ET-pH图，分析了硅酸锌硫酸浸出和原硅酸高温脱硅的热力学可行性. 通过人工合成硅酸锌的加压酸浸实验，考察了始酸浓度、终点pH值、铁含量、硫酸铝添加量、浸出温度对硅酸锌酸浸和硅酸凝聚的影响. 结果表明，升高浸出温度能有效降低硅溶胶的稳定性且有利于原硅酸的高温脱硅过程，进而改善矿浆的过滤性能；硫酸铝能促使硅溶胶凝结析出，可降低硅酸浓度；控制恰当的矿浆终点pH值和Si/Fe及Si/Al质量比均有助于硅析出. 在浸出温度120℃、浸出时间0.5 h、液固比8 mL/g及H2SO4浓度120 g/L的优化条件下，锌、硅浸出率分别约为98%和1%.

Thermodynamic Analysis and Experiment on Pressure Leaching of Zinc Silicate with Sulfuric Acid

The ET-pH diagram of Zn-Si-H2O system was calculated and plotted. Thermodynamic analysis on the feasibility of sulfuric acid leaching of zinc silicate and desilication of orthosilicate at high temperature was analyzed. With pressure acid leaching of synthetic zinc silicate, the effects of initial concentration of sulfuric acid, final pH value, iron content, added amount of aluminum sulfate and temperature on acid leaching of zinc silicate and condensation of silicic acid were examined. The experimental results show that increasing of leaching temperature can effectively undermine the stability of silica and advantageously promote the desilication process at high temperature, as the filtering performance of slurry can be improved. The aluminum sulfate can promote the condensation and precipitation of silicone and reduce the concentration of silicate. Silica would advantageously precipitate when the final pH value of the slurry and mass ratios of Si to Fe and Si to Al were properly controlled. The optimum conditions for the pressure leaching of zinc silicate are leaching time 0.5 h at 120℃, ratio of liquid to solid 8 mL/g and H2SO4 concentration of 120 g/L. Under the conditions, the leaching rates of Zn and Si are 98% and 1%, respectively.