Effects of Flotation Reagents on the Morphology of Magnesium Hydroxide: Experimental and Simulation Study

Abstract

The flotation process to extract potassium salt from carnallite ores could produce the MgCl 2 mother liquor with flotation reagents�octadecyl amine hydrochloride (ODA) and dodecyl morpholine (DMP). The organic impurities would further affect MgCl 2 resource-integrated utilization for preparing magnesium hydroxide (MH). In this study, the effects of flotation reagents with different concentrations on the morphology of MH were investigated at a hydrothermal temperature of 200 °C for 6 h with the hydrothermal medium of a 4 mol/L NaOH solution. It was observed that the average thickness of MH crystal plates increased and the morphology of crystals changed from regular hexagonal plates to irregular polygonal plates with the increase of ODA and DMP concentrations. Molecular dynamics (MD) simulation was applied to further explain the effect mechanism. The results indicated that ODA and DMP molecules were more likely to be adsorbed on the (1 1 0) plane in contrast to the (0 0 1) plane due to the larger absolute values of adsorption energy on the (1 1 0) plane. The long carbon chains far away from the (1 1 0) plane would form steric hindrance to affect the growth rate of MH crystals in the [1 1 0] direction.

Metastable Zone Width and Primary Nucleation Kinetics for Crystallization of KCl from a KCl-MgCl2-H2O System

“…Based on the optimized structure, MD simulation was conducted in the Forcite module. During structure optimization in the Dmol3 module, the details with simulation parameters were the same as those listed in the literature . To investigate the effect of DMP on diffusion of K + and Cl – , two solution boxes were constructed by the Amorphous Cell module to simulate KCl-MgCl 2 -H 2 O mixed solutions with and without the flotation reagent, respectively.…”