Beneficiation of a Nigerian lepidolite ore by sulfuric acid leaching

ABSTRACT The dissolution of a Nigerian lepidolite ore in sulphuric acid solution for its optimal industrial transformation was carried out. The degree of influence of the acid concentration, reaction temperature, particle diameter, and reaction time on the rate of the ore dissolution was investigated. These parameters were observed to enhance the rate of the dissolution as the acid concentration was increased from 0.1 to 1.5 mol/L, reaction temperature from room temperature (27 ± 2°C) to 75°C, particle diameter from 63 to 90 µm and reaction time from 5 to 120 min, respectively. The ore dissolution kinetics was studied using the shrinking core model, based on which the process was found to follow a diffusion-controlled mechanism as the rate-determining step. The activation energy of 18.1 kJ/mol lends support to this assertion. At optimal conditions, the formation of a pure lepidolite crystal (K2Li3Al3Si7O21F3: (96-900-0834)), recommended as a precursor for preparing industrial lithium sulphate was obtained.