Method for the separation of non-ferrous metals and ree from the mother liquor of the crystallization process AlCl3·6H2O

Abstract

The paper analyzes the raw material base of the coal deposit in the world and Kazakhstan. It is shown that with the development of the coal industry, the output of ash and slag waste is growing, which occupy large areas for storage and their negative impact on the environment. The paper describes the mechanism of the process of rectification of the mother liquor with ammonium hydroxide with the release of non-ferrous metals and REE into the precipitate (cake) and the production of a circulating solution based on calcium chloride. The results of thermodynamic calculations of the Gibbs free energy of deposition of non-ferrous metals from the mother liquor in the temperature range of 293-323 K (20-50°C), showed the fundamental possibility of separation of non-ferrous metals into the precipitate. The results of thermodynamic calculations are fully confirmed by experimental experiments on the study of the regularities of the separation of non-ferrous metals (CM) and REE into the target commercial product (cake) from the mother liquor obtained after crystallization of aluminum chloride hexahydrate by rectification with NH₄OH. In the process of rectification of the mother liquor, a solution of calcium chloride in the amount of 989.9 ml and 11.91 g of cake (precipitate) containing NFM and REE was obtained. The resulting solution is reversible and is used for chlorinating ash firing. A high (more than 99%) extraction of NFM and REE in the cake was established. According to the phase composition, the cake consists of NFM and calcium hydroxides, with a predominant, up to 50%, content Zn(OH)₂. The cake can be easily processed by known metallurgical methods with maximum extraction of NFM and REE. The process of rectification of the mother liquor is the final stage of the innovative technology of complex processing of ash and slag waste of the TPS of Kazakhstan. The paper shows the technological scheme of the developed technology of complex ash processing and optimal technological parameters. The technology will stimulate the development of the energy industry by completely recycling them to obtain commodity products with high added value and increase the efficiency of thermal power plants operating on coal combustion by involving ash waste in processing as an additional source of raw materials.