Mechanistic insights into in-situ detoxification during co-extraction of lithium and beryllium from Lepidolite via potassium bisulfate roasting

Conventional lithium extraction from lepidolite often faces contamination challenges from associated toxic elements, notably Beryllium. To address this issue, this study innovatively proposes a roasting-water leaching process using potassium bisulfate as an additive. Through systematic optimization of process parameters under ideal conditions (roasting temperature: 950 °C, duration: 120 min, lepidolite concentrate-to-potassium hydrogen sulfate mass ratio: 1:0.7; leaching liquid-to-solid ratio: 2:1, temperature: 20 °C, time: 30 min), leaching efficiencies of lithium, beryllium, and manganese reached 90.7 %, 98.9 %, and 92.7 %, respectively, while Aluminum and Iron leaching rates were suppressed to below 1.5 %. Subsequent neutralization and precipitation of the leachate with Potassium carbonate (final pH=8) enriched beryllium in the neutralization residue with a 34-fold enrichment factor (Beryllium oxide content: 1.27 %) and minimal lithium loss (3 %). Toxicity characteristic leaching procedure tests confirmed that leached concentrations of hazardous elements (for example, Beryllium) in the lithium residue complied with the Chinese National Standard for Hazardous Waste Identification (GB 5085.3–2007), supporting its safe resource utilization. This integrated approach simultaneously resolves the dual challenges of high-efficiency lithium recovery and beryllium pollution mitigation, offering a sustainable pathway for green comprehensive extraction from lepidolite resources.