This study investigates the activation behavior and mechanism of calcium ions on the flotation of spodumene with different colors. Using NaOL as a collector, in descending order of flotation recoveries were purple, pink, and white spodumene, while in the presence of CaCl2, the flotation recoveries were increased and the order was pink, white, and purple spodumene. The zeta potential, adsorption amount, contact angle, and AFM measurements demonstrated that calcium ions adsorbed on the spodumene surface and promoted NaOL adsorption in alkaline conditions. Species distribution analysis showed that Ca2+, Ca(OH)+, and Ca(OH)2 were essential components that play an activation role at pH = 12. The adsorption capacity and XPS results illustrated that CaCl2 activated spodumene flotation in two ways. One possibility involves calcium ions and their hydroxyl compounds being adsorbed on the spodumene surface, where Ca and Al sites favored OL− adsorption. The other possible way involves calcium ions and their hydroxyl compounds forming complexes with NaOL firstly in solution and then co-adsorbing on the spodumene surface. Quantum chemical calculations showed that the adsorption affinity on the spodumene surface in descending order was Ca2+, Ca(OH)2, and Ca(OH)+, and the pink spodumene was most preferably adsorbed, followed by the white spodumene, also consistent the flotation results.
