An attempt to recover potassium from mechanochemically activated phlogopite via ultrasound assisted acid leaching and precipitation of impurities

Phlogopite, a potassium-bearing mica obtained as a byproduct of mining activities, represents a potential secondary resource for potassium recovery and valorization. Potassium among its elements is the most readily released, making phlogopite a subject of interest for resource utilization. This study evaluated K extraction from phlogopite using a process involving gypsum-assisted milling, acid leaching, and ultrasound treatment to improve recovery efficiency. The main goal was to assess the practicality of this method for resource recovery and the broader utilization of phlogopite. Results show that adding gypsum during milling increases leaching efficiency when combined with ultrasound and citric acid, resulting in a K extraction yield of approximately 80%. The process enables phlogopite valorization at progressively increasing solid-to-liquid ratios, within a short operation time of 30 min, thereby enhancing efficiency and reducing environmental impact. While the approach effectively released K and provided data on residue characterization, issues such as silica gel formation, residual citric acid in the solution, and further purification requirements were observed. These findings contribute to understanding the leaching behavior of phlogopite and its potential use as an alternative K source under specified conditions.