Magnesium Chloride Crystals with Studying Mechanism and Leaching Kinetics of Serpentinite Ore by Hydrochloric Acid

Abstract

Abstract Magnesium chloride hexahydrate crystal (MgCl 2 .6H 2 O) is an intermediate product used to obtain Mg metal from its ores. This work aims to produce purified MgCl 2 .6H 2 O crystals from natural Egyptian serpentine. Serpentine samples were collected from the Eastern Desert in Egypt and prepared for leaching with HCl solutions. Reaction temperature (°C), leaching time (h), solid/liquid ratio (g/mL), and acid concentration (M) were studied. The optimum leaching conditions achieved 97.6% MgO recovery optimized at particle size less than 75 µm (100%), 95 °C of the reaction temperature for three hours with solid-to-liquid ratio 1:5, and 5 M of HCl concentration. The serpentine dissolution kinetics were studied depending on the solid–liquid reaction and activation energy model. The resultant liquor was purified and crystallized. The kinetic studies indicated that product layer diffusion is the most likely rate-controlling step for serpentinite dissolution in the HCl solution.