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本文研究了一水硬铝石型铝土矿的溶出动力学。 通过对一水硬铝石矿Bayer法溶出过程主要特征的研究,并基于动力学稳态原理,推导了溶出反应速度方程: V=kS[(C_N—C_A)/K_E] 式中,k为表观速度常数;S为反应表面积;C_N,C_A分别为溶液中氢氧根和铝酸根的摩尔浓度;K_E为溶出反应平衡常数。 应用等溶出率方法处理了平果铝土矿溶出动力学数据。结果表明,一水硬铝石表面反应有关离子的反应级数为1的假设是合理的。224—242℃之间,平果矿溶出表观活化能为89.5 kJ/mol,反应为动力学控制区;当温度升至242—268℃,表观活化能降至44.4 kJ/mol,溶出过程处于表面化学反应及传质步骤的影响应予同时考虑的过渡区。

On the basis of steady state principle of kinetics and experimental results, a rate equation was derived: V=kS[(C_N—C_A)/K_E], where V=digestion rate; k=rate constant; S=surface area of diaspore in bauxite; C_N, C_A=concentrations of hydroxide and aluminate ions, mol/L; K_E=equilibrium constant of digestion reaction. An equal-digestion-efficiency method was developed and used to process the digestion kinetics data of Pingguo bauxite. The results show that the chemical reactions on the diaspore surface are of first order to the hydroxide and aluminate ions. At 224—242℃ the apparent activation energy was calculated as 89.5 kJ/mol. It is obvious that in this temperature range the digestion process of Pingguo bauxite is controled by chemical reaction on diaspore surface. At 242—268℃ the Arrhenius plot slope changes rapidly and the apparent activation energy was found to be 44.4 kJ/mol. It is believed that the effect of mass-transfer step on digestion rate should be taken into consideration at 242—268℃.