摘要
Multi-scale analyses reveal SG’s selective adsorption on mineral surfaces. • The SG–Na 2 CO 3 system enables selective cassiterite separation from calcite. • SG coordinates with Ca 2+ sites, greatly increasing calcite surface hydrophilicity. • MD shows SG strongly increases calcite hydrophilicity, but cassiterite changes little. Cassiterite and calcite commonly occur in close association and exhibit similar flotation behavior, making their selective separation particularly challenging. Therefore, developing a highly selective calcite depressant is critical for improving tin recovery. In this study, a composite depressant system consisting of sodium gluconate (SG)–Na 2 CO 3 was developed for the selective flotation separation of cassiterite from calcite. Flotation tests on artificial mineral mixtures showed that, using SG alone, the concentrate Sn grade and recovery were 48.25% and 75.72%, respectively. With Na 2 CO 3 addition, these values increased to 67.78% and 89.90%, respectively, while the CaO grade and recovery decreased by 10.8 and 28.89 percentage points. To clarify the mechanism, contact angle, Zeta potential, XPS, reaction heat, ToF–SIMS, and MD simulations were conducted. The results indicated that SG selectively coordinated with surface Ca active sites on calcite via carboxylate groups, thereby increasing surface hydrophilicity and inhibiting OHA adsorption. Na 2 CO 3 mainly complexed dissolved Ca 2+ released by calcite dissolution, reducing the nonproductive consumption of SG and promoting its interaction with calcite surface sites. MD simulations further confirmed that SG markedly increased the hydrophilicity of calcite, while having limited effect on cassiterite. Overall, this study provides an effective strategy for the selective flotation separation of cassiterite from calcite. Download: Download high-res image (208KB) Download: Download full-size image
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