Carnallite decomposition into magnesia,hydrochloric acid and potassium chloride: A thermal analysis study; formation of pure periclase

A thermal analysis study of the one-stage decomposition of small (mg) quantities of carnallite, KCl. MgCl₂, 6H₂O → KCl + MgO + 5H₂O ↑ + 2HCl ↓, showed that dehydration and hydrolysis require temperatures above 300 °C. Decomposition of greater amounts, and analysis of the products, showed that at 450 °C, 88 to 90% of the magnesium occurs as chloride-free high-purity periclase. At higher temperatures increasing amounts of chlorides remain in the periclase and are difficult to separate. Unglazed porcelain is a suitable material for the decomposition vessel.