Comprehensive Utilization Beneficiation Process of Lithium Pegmatite Ore: A Pilot-Scale Study

Abstract

Pegmatite ores, the primary and technologically advanced lithium (Li)-bearing minerals, comprise various rare metal-based elements, including niobium (Nb), tantalum (Ta), tin (Sn), and beryllium. With increasing Li demand, global exploitation of pegmatite ores has generated vast tailings, mainly comprising quartz and feldspar. However, the process for comprehensively utilizing valuable minerals from pegmatite ores remains undeveloped, and the persistent gap between laboratory studies and industrial practice hinders the sustainable advancement of the pegmatite mineral processing industry. Herein, a comprehensive utilization beneficiation process was designed and validated at both laboratory- and pilot-scale levels. Locked-circuit flotation tests at the laboratory-scale on spodumene and feldspar yielded (i) an Li concentrate with an Li2O grade of 5.80% and recovery of 88.62%, and (ii) a feldspar concentrate with a (K2O + Na2O) grade of 11.41% and good recoveries of K2O (81.30%) and Na2O (84.81%). In a 72 h continuous pilot-scale test, an Li flotation concentrate with an Li2O grade of 5.72% and recovery of 86.78%, and a final Li concentrate with an Li2O grade of 5.89% and recovery of 86.56% were obtained. Using Li flotation tailings as feed, a feldspar concentrate with a (K2O + Na2O) grade of 11.41% was obtained, achieving K2O and Na2O recoveries of >75%. The proposed process realizes nearly overall mineral recovery from the pegmatite ores, producing qualified concentrates of Li, Nb–Ta, Sn, feldspar, and quartz. In water reuse feasibility tests, ferrous sulfate (FeSO4) was identified as the optimum flocculant at a dosage of 1000 g m−3. In the locked-circuit test with returned water, the consumption of sodium hydroxide (NaOH), sodium carbonate (Na2CO3), and EMT-12 (collector) was reduced by 18.75%, 3.33%, and 3.45%, respectively, while the flotation indices of the Li concentrate (Li2O grade of 5.77% and recovery of 86.47%) were slightly lower than those in freshwater. In addition to increasing economic benefits, the process offers considerable reductions in tailings disposal, full utilization of multiple elements, and a potential decrease in water and reagent consumption. This study provides important guidelines for the mineral processing of Li pegmatite and other associated multimetallic ores.