The role of Mg value and moisture content of decomposed products during the decomposition process of carnallite in aqueous solution: a novel monitoring method

The amount of water is the crucial factor for the decomposition of carnallite in aqueous solution. A novel method for monitoring the decomposition process of carnallite in aqueous solution based on the Mg value and moisture content of the decomposed products was investigated in this study. Based on the principle of mass conservation of MgCl₂ during the decomposition of carnallite in aqueous solution, a functional model of Mg value in decomposed products was established. The functional model of moisture content in decomposed products was obtained by the water equilibrium condition of the reaction system. The experiments were performed by dissolving carnallite in aqueous solution under different water conditions, and the Mg value and moisture content were determined for the decomposed products. The results showed that: (1) the Mg value and moisture content of the decomposed products have a nonlinear variation when the amount of water used to dissolve carnallite is not suitable, and (2) an excess amount of water used to dissolve carnallite would lead to a linear change in the Mg value and moisture content of the decomposed products. It was found that the intersection of these two changes is the appropriate location for the decomposition of carnallite in aqueous solution. The Mg value and moisture content of the decomposed products are thus presented as a novel monitoring method for these applications within the potash processing industry.