氢氧化钠-磷酸盐浸出白钨矿精矿动力学

Leaching kinetics of scheelite concentrate with sodium hydroxide in the presence of phosphate

以低品位白钨精矿为研究对象,在高压反应釜体系中研究白钨精矿在氢氧化钠-磷酸盐溶液中的反应动力学,考察搅拌速度(300～600r/min)、反应温度(353～383K)、氢氧化钠浓度(1.69～6.76mol/L)和磷酸盐浓度(0.68～1.69 mol/L)对WO_3浸出率的影响。结果表明,WO_3浸出率与搅拌速度无关,但随着反应温度、氢氧化钠浓度和磷酸盐浓度的增加而升高。实验结果遵循收缩核模型,即浸出速率由原料和产物的表面化学反应控制。浸出反应的表观活化能为49.56kJ/mol,氢氧化钠浓度和磷酸盐浓度的反应级数分别为0.27和0.67。该浸出过程动力学方程可以根据相关结果和数据建立。

The reaction kinetics for the leaching of low-grade scheelite concentrate was investigated in an autoclave with sodium hydroxide in the presence of phosphate. The effects of stirring speed (300-600 r/min), reaction temperature (353-383 K), sodium hydroxide concentration (1.69-6.76 mol/L) and phosphate concentration (0.68-1.69 mol/L) on the WO3 dissolution ratio were studied. The results showed that the WO3 dissolution ratio was practically independent of stirring speed, while it increased with increasing the reaction temperature, and the concentrations of sodium hydroxide and phosphate. The experimental data were consistent with the shrinking core model, with a surface chemical reaction as the leaching rate-determining step. The apparent activation energy was calculated as 49.56 kJ/mol, and the reaction orders with respect to the concentrations of sodium hydroxide and phosphate were determined as 0.27 and 0.67, respectively. The kinetics equation of the leaching process was established.