Roasting-leaching experiments on glauconitic rocks of Bakchar ironstone deposit (Western Siberia) for evaluation their fertilizer potential

This study examines factors favouring optimal release of potassium from a glauconitic rock by moderate roasting-leaching. Sieving and electromagnetic separation of oolitic iron ore deposit increases the concentration of glauconite grains substantially. Roasting and chemical leaching of this concentrate enhances the release of potassium as interlayer structures of glauconite collapses. This study records the percentage of potassium recovered from glauconite under different experimental conditions, viz., temperature, reaction time, concentration as well as volume of HCl and stages involved in the leaching treatment. Leaching of glauconite without roasting results a low recovery (<15%) of K at room temperature. The recovery of K content from the sample increases markedly with increase in concentration of HCl, leaching time, and the ratio by mass of sample to HCl, and marginally with increased stages of leaching. Roasting at 900 °C recovers maximum K up to 62–63% for one-stage leaching treatment at 100 °C for 120 min with a 4 mol∙l⁻¹ HCl solution for a sample: HCl ratio of 1:5. The roasting-leaching method, therefore, holds promise for converting glauconite to potash salts for agronomic applications.