Investigation of the solid oxidizer effect on the metal geotechnology efficiency

Abstract

Purpose. The research is aimed at increasing the useful component content in a pregnant solution during in-situ leaching (ISL) using a solid oxidizer and increasing the ferric iron concentration in the leaching solution based on laboratory research. Methods. Laboratory research is performed on a specially developed model electrolyzer for obtaining comparative data on divalent iron oxidation to trivalent iron and the change in the useful component content in a pregnant solution. Firstly, tests are conducted with a basic leaching solution, then on the oxidation of the leaching solution with a solid oxidizer in the form of a lead dioxide plate. Tests are conducted by changing sulphuric acid concentration within 5-50 g/l, amount of divalent iron ions in the solution from 0.5 up to 4.0 g, lead dioxide plate surface area from 19 to 76 cm2. The leaching time is up to 10 hours. Findings. The results of laboratory research on determining the oxidation degree of divalent iron ions and change in the oxidation-reduction potential (ORP) depending on the sulphuric acid concentration and on the initial concentration of divalent iron ions in the initial solution are presented. With a change in the sulphuric acid concentration from 5 to 50 g/l, the oxidation value of divalent iron ions increases from 26.5 to 96.5%, and with an increase in the initial solution concentration of divalent iron, the oxidation degree of divalent iron naturally decreases from 95.2 to 58.8%. In the initial leaching solution, the divalent solution concentration is 312 mg/l, and that of the trivalent solution is 288 mg/l. After oxidation with a solid oxidizer, the divalent and trivalent iron concentrations are 56 and 392 mg/l, respectively. In the course of further laboratory research using core materials from a uranium deposit, it has been revealed that when leaching with a basic solution, the uranium content in the pregnant solution is 19.36 mg/l, and when leaching with a solution after oxidation with a solid oxidizer, it is 27.9 mg/l, which is by 8.54 mg/l more. Originality. New dependences have been determined of the oxidation degree of divalent iron ions to trivalent one on the sulphuric acid concentration and on the initial concentration of divalent iron ions, as well as the useful component content in the pregnant solution on the leaching time when using a solid oxidizer. Practical implications. Using of a solid oxidizer, it is possible to increase the trivalent iron concentration in the leaching solution and the useful component content in the pregnant solution compared with the basic technology, thereby reducing the time of mining uranium reserves. Proposed technology is environmentally friendly, with low capital costs.