Carnallite synthesis from magnesium and potassium chloride solutions

The influence of the main parameters on the process of obtaining artificial carnallite and its quality has been established. It is shown that to obtain a product with a high content of the carnallite phase and a low content of bischofite and KCl, it is necessary to use magnesium chloride solution with the concentration of 27-30 % and preheated ground potassium chloride. The process should be carried out at the temperature of 80 °C. The formation of synthetic carnallite, close in composition to the enriched one, occurs when the ratio of potassium chloride to magnesium chloride in the initial mixture is equal or close to their stoichiometric ratio in carnallite. With an excess of potassium chloride in the reaction mixture, an increased content of potassium and sodium chlorides in the product is observed, and with its deficiency, the product contains an increased amount of bischofite phase. To reduce the hydrolysis of magnesium chloride during dehydration, a slight excess of potassium chloride should be maintained in the mixture entering the synthesis. It is shown that the most advantageous scheme for producing artificial carnallite provides for incomplete evaporation of desulfurized liquor in the presence of potassium chloride with the return of circulating carnallite liquor to the desulfurization stage.

1. Pozin M. E. Technology of mineral salts. Part 1. Leningrad, Khimiya Publ., 1970. 792 p. (in Russian).

2. Burdin I. V., Poylov V. Z. Kinetics of polythermal crystallization of carnallite. Vestnik Kazanskogo tekhnologicheskogo universiteta = Bulletin of Kazan Technological University, 2006, no. 3, pp. 13-19 (in Russian).

3. Shirev M. Yu., Lebedev V. А. New process of synthetic carnallite production. Izvestiya vuzov. Tsvetnaya metallurgiya = Universities' Proceedings. Nonferrous Metallurgy, 2011, no. 6, pp. 25-30 (in Russian).