红土镍矿在NaOH亚熔盐体系中的预脱硅

Pre-desilication of laterite in NaOH sub-molten salt system

研究常压下高浓度氢氧化钠浸取红土镍矿的预脱硅过程,考察搅拌强度、液固比、氢氧化钠浓度、反应温度和原矿粒径对红土镍矿中硅的反应率的影响。结果表明:二氧化硅的反应率受克-金-布产物层固膜扩散控制,并由阿累尼乌斯方程得到反应的表观活化能为53.74kJ/mol。结合动力学实验结果和电子扫描电镜(SEM)及X射线能谱(EDAX)分析,证明在反应过程中通过固相产物层的内扩散为反应过程的控制步骤。

The leaching mechanism of silicon dioxide from a laterite by concentrated NaOH under the atmosphere pressure was studied. The effects of stirring speed, mass ratio of alkali-to-ore, initial NaOH concentration, reaction temperature and particle size on the reaction rate of silicon dioxide were reported. The results show that the experimental data of the reaction rate are fit to the Crank-Ginsting-Braunshtein＇s diffusion-through-layer-reaction-control-model. According to the Arrhenius expression, the apparent activation energy for the leaching reaction is 53.74 kJ/mol. The results of the kinetic experiment and SEM and EDAX analysis prove that the internal diffusion on the solid product layer is the rate-controlling step in the leaching process.