Phosphonic acid derivative-driven surface reconstruction: An efficient strategy to overcome lizardite coating contamination in copper sulfide ore flotation

Abstract

Surface properties and interfacial interactions are the core mechanisms for regulating foam flotation. Lizardite, a representative magnesium-bearing silicate, serves as the primary contaminant adhering to copper sulfide ore surfaces due to its distinctive surface characteristics. Conventional dispersants for alleviating hetero-coagulation are constrained by the limitations: high operational costs, suboptimal efficiency, and environmental pollution. In this study, diethylenetriamine pentamethylene phosphonic acid (DTPMP), a novel highly effective scale inhibitor with demonstrated superior performance in recent studies, was innovatively employed to address the challenge of lizardite coating adhesion on chalcopyrite surfaces. Flotation experiments revealed that DTPMP significantly enhanced chalcopyrite-lizardite separation across a broad pH range. A high-quality copper concentrate with a recovery of 93.07 % and copper grade of 30.92 % was obtained in natural pH conditions with a DTPMP concentration of 60 mg/L. Through SEM-EDS morphology, DRIFT spectroscopy, UV–Vis spectroscopy, zeta potential, ICP-OES, and solution chemistry analyses, DTPMP was found to selectively adsorb onto the lizardite surface. Complexation facilitated the dissolution of lizardite surfaces, markedly increasing their negative charge density. This process induced electrostatic repulsion between lizardite and chalcopyrite, eliminating hetero-aggregation, as supported by DLVO theory. As a lizardite depressant, DTPMP also activated PAX adsorption on chalcopyrite surfaces. XPS and DFT analyses confirmed that multiple phosphonic acid groups in DTPMP exhibited strong nucleophilic reactivity. Oxygen anions in these functional groups spontaneously formed stable ionic bonds with exposed Mg ions on lizardite surfaces, enabling chemical adsorption. The high efficiency of DTPMP highlights its enormous potential for purifying chalcopyrite from magnesium-bearing silicate.