Chemical, morphological, and kinetic study of lead extraction from the Koni Mansur polymetallic deposit

Abstract

Located in the north of Tajikistan, the Koni Mansur is a rich polymetallic deposit that besides other metals has high concentration of lead-containing mineral galena. The hydro metallurgical extraction of lead from the Koni Mansur lead sulfide (galena) mineral in acidic media, its chemical composition and morphological properties in comparison to the Balya deposit in Turkey are reported for the first time. Energy dispersive X-ray fluorescence spectrometry was applied for chemical analysis of galena, while mineralogical characterization before and after lead acidic extraction was performed by XRD. The nitric acid concentration, temperature, duration of the extraction process, and the particle size distribution before and after extraction have been evaluated. The amount of lead in solution after extraction and solid-liquid phase separation was determined by the flame atomic absorption spectroscopy (FAAS). The particle size distribution before and after lead extraction revealed no significant changes. Assuming spherical shape of the particles, the Shrinking Core Model (SCM) used for kinetic study of the lead extraction allowed to define the activation energies and changes in the corresponding reaction mechanisms. Specifically, the activation energy at 293-318 K (12.4 kJ/mol) was significantly lower than at higher temperatures (318-338 K) reaching similar to 46.778 kJ/mol which indicates the corresponding change in the extraction mechanism.