Kinetics and technology of galenite-containing Koni Mansur concentrate processing

Abstract

This study presents the characteristics of the Koni Mansur (Tajikistan) galena concentrate along with the kinetic study results for its leaching in the nitric acid solution. The main minerals (phases) of this concentrate are galena (PbS), sphalerite (ZnS), pyrite (FeS₂), chalcopyrite (CuFeS₂), anglesite (PbSO₄) and quartz (SiO₂). The study uses a sample of the concentrate with the following chemical composition, wt.%: Pb – 46.56, Zn – 4.01, Fe – 20.55, Cu – 2.03, S – 21.78, Si – 3.78 and Al – 1.29. The concentrate particle size varies between 0.84 and 148.26 μm. Optimal conditions for the concentrate nitric acid leaching are found to be: temperature t = 55÷65 °C, acid concentration 1.5–2.0 M and the time of concentrate and acid mixture processing 70–90 min. The leaching of concentrate minerals in the acid solution follows the shrinking core mechanism, at 45–65 °C within the kinetic region and with activation energy E = 46.78 kJ/mol. At temperatures below 45 °C, the concentrate nitric acid leaching reaction is inhibited by acid diffusion transfer to the surface of particles with activation energy E = 12.4 kJ/mol. The concentrate processing flow chart is proposed based on the kinetic study results obtained for the mineral leaching process with its main stages described as zero-emission and zero-waste, environmentally friendly, and implemented in a closed cyclic mode with nitric acid regeneration. This results in a significantly cost-effective route for the concentrate leaching process. The resulting associated chemicals are valuable for use in a wide range of industries.