INCREASED EFFICIENCY OF LEACHING OF RADIONUCLIDES, HEAVY AND RARE METALS FROM SOILS AND WASTES OF MOUNTAIN AND TECHNOLOGICAL MANUFACTURES

Abstract

The article considers the methods of multiple and multi-stage leaching, as well as leaching in countercurrents with solutions that allow to transfer to a water-soluble state of the required amount of highly sorbable compounds, such as radionuclides, heavy and rare metals from soils, rocks and wastes of mining industries. The developed methods of calculation are presented, allowing due the choosing of optimal methods and parameters to reduce the consumption of solutions and increase the concentration of extracted elements in them. It has been established that the most promising methods of extraction are multistage leaching and exchange in countercurrents of the leaching solution and the material to be processed.
 The removal of radionuclides from soils and the extraction of rare metals from mining waste can be carried out by leaching, which requires a large consumption of chemical reagents. Therefore, it becomes necessary to identify the optimal leaching parameters by mathematical modeling. With this aim, the article proposed methods to reduce the consumption of leaching solutions, and determined the optimal parameters of leaching under specified conditions. For all the methods considered, analytical solutions are given that allow calculating the degree of purification from the extracted compounds, the consumption of the leaching solution and its concentration. А system of equations for multi-stage leaching has been solved. It was found that with a distribution coefficient of 5, in order to achieve a purification degree of 10 %, 3 times less solution will be consumed with four-fold leaching than with one-time leaching, and with multistage
 leaching, 9 times less.