Novel Depressant Based on Hybridization Theory for the Separation of Galena and Realgar: Experimental Study and Adsorption Mechanism

In lead concentrate cleaning, achieving efficient separation of galena from realgar—both significant naturally floatable minerals-relies critically on selective galena depression. This study introduces dimercaptosuccinic acid (DMSA) as a novel organic depressant by leveraging its distinct carbon-sulfur hybridization compared to diethyldithiocarbamate (DDTC). Quantum chemical analyses reveal that the sp3-hybridized sulfur in DMSA exhibits enhanced p-orbital reactivity, enabling stronger chemical adsorption on galena via Pb-S bonding. At pH 6.5, DMSA (4 mg/L) achieved optimal separation with a separation index of 11.88, outperforming DDTC (10 mg/L). FTIR/XPS confirmed DMSA’s chemisorption on galena, while theoretical calculations highlighted its superior Pb-S bond strength compared to DDTC. Notably, DMSA’s lower dosage and reduced environmental impact position it as a sustainable alternative to inorganic depressants. This work provides fundamental insights into sulfur orbital-driven adsorption mechanisms, advancing the rational design of eco-friendly flotation reagents.