Pre-treatment for the extraction of manganese from mangano-argentiferous refractory tailings

A novel process was used to extract manganese from minerals that are refractory to cyanidation and ammonium thiosulphate. These minerals, known as mangano-argentiferous compounds, are principally composed of manganese, silver, and iron and exhibit low recovery. The mineral of interest was obtained from the leaching tails procured in Monte del Favor, Hostotipaquillo, Jalisco, Mexico. The tailings were characterised by X-ray powder diffraction (XRD), atomic absorption, and energy dispersive X-ray spectroscopy (EDS) microanalysis. After mineralogical characterisation, the tailings were screened through a mesh (mesh number 100, 0.147 mm); later, they were subjected to a reductive leaching process, where the solid–liquid ratio was varied from 2:1 to 10:1. A 5:1 ratio yielded the highest manganese content. With sulphuric acid and sodium sulphite as the reducing agents, 96.05% of Mn could be extracted during the first 3 h, with a head grade of 3.58% and an acid consumption of 49.31 kg/t. The sulphite consumption was found to be 9.81 kg/t.