INVESTIGATION INTO THE LEACHING KINETICS AND MECHANISM OF NICKEL EXTRACTION FROM ASBESTOS TAILINGS VIA NITRIC ACID TREATMENT

Abstract

This study presents the results of an investigation into the kinetics of nitric acid leaching of nickel from the magnetic fraction of chrysotile asbestos beneficiation waste. The relevance of this work stems from the necessity to involve large-tonnage technogenic formations into processing circuits. It was established that the application of magnetic separation enables preliminary concentration of nickel, thereby enhancing the efficiency of subsequent hydrometallurgical processing. The experimental study examined the influence of temperature (25–85 °C) and process duration on the extraction degree of the valuable component. To identify the reaction mechanism, kinetic modeling was performed using the Jander, Drozdov-Rotinyan, Prout-Tompkins, and Johnson-Mehl-Avrami-Kolmogorov (JMAK) equations. The calculated apparent activation energy (E_а = 18.4 kJ mol^-1) indicates that the process proceeds under diffusion-controlled conditions. The obtained results establish a scientific and practical foundation for developing a low-waste technology for processing asbestos tailings with the concurrent production of marketable nickel compounds.