钾光卤石溶解和氯化钾结晶动力学与机理研究

Study on the Dissolution Kinetics and Mechanium of Carnallite and KCl

本文研究了易溶性复盐钾光卤石(KCl·MgCl_2·6H_2O)的溶解机理及动力学。利用相图控制在固相光卤石饱和区的情况下研究改变温度、浓度、搅拌速度及成块压力对光卤石溶解过程的影响,发现MgCl_2、KCl首先以近相等的速度且出现KCl:MgCl_2的摩尔比值>1进入溶液,随后KCl从溶液中结晶出来。KCl在整个溶解过程中明显分为两个阶段,即以溶解为主导的过程和以结晶为主导的过程;在溶解时,MgCl_2受扩散控制,KCl属化学溶解过程,KCl结晶受扩散控制,获得了动力学的方程计算出MgCl_2的溶解活化能和KCl的溶解和结晶活化能。

In this paper the kinetics of dissolution and mechanium of very soluble double salt carnallite (KCl·MgCl_2·6H_2O) in solution have been studied. The system point must be in saturated area of carnallite at the dissolution equlibriurn according to the phase diagram of KCl—MgCl_2—H_2O system. The influences of temperature, concentration, stirring rate and pressure on the dissolution of carnallite have been investigated. The results show that MgCl_2 and KCl enter into the solution at approximately equal speed with the mole ratio KCl:MgCl_2>1 at the some time and KCl crystallized from solution consequently. KCl was clearly divided into two stages, dissolution and crystallization, which played a leading role during the process of decomposition. The dissolution rate of MgCl_2 is controlled by diffusion while KCl belongs to chemical dissolution; and KCl crystallization is controlled by diffusion, from which kinetic equation was obtanied and the activation energy of MgCl_2 dissolution was calculated and the cystallization activation energy of KCl was estimated.