超声波场作用下Na_3PO_4分解白钨矿的动力学

Kinetics of scheelite concentrate leached by sodium phosphate under ultrasound

研究有无超声波作用下Na_3PO_4分解白钨矿的动力学。考察浸出温度、Na_3PO_4浓度、NaOH浓度和矿物粒径对白钨矿浸出速率的影响。结果表明:超声波场的引入加快了白钨矿浸出过程中的反应速率;超声波场的作用使得浸出过程由扩散控制转变为化学反应控制,浸出反应的表观活化能也从78 kJ/mol降低至50 kJ/mol;在超声波作用下反应级数减小,NaOH的反应级数由0.34降为0.07:而当Na_3PO_4浓度高于02 mol/kg后,其反应级数从0.39减为0。

The leaching kinetics of scheelite concentrates by sodium phosphate in the absence or presence of ultrasound was approached. The influences of leaching temperature, Na3PO4 concentration, NaOH concentration and particle size of mineral on the leaching rate of scheelite concentrate were investigated. The results show that ultrasound accelerates the leaching rate of the scheelite concentrate. The diffusion through the solid film is the rate limiting step in the decomposition process of scheelite concentrate in the absence of ultrasound. In the presence of ultrasound, the rate limiting step changes from the diffusion through solid film to the chemical reaction, and the apparent activation energy changes from 78 to 50 kJ/mol. Compared with the results in the absence or presence of ultrasound, the apparent reaction order of NaOH decreases from 0.34 to 0.07, and the apparent reaction order of Na3PO4 decreases from 0.39 to 0 when the concentration of Na3PO4 is up to 0.2 mol/kg.