Insights Into Flotation Separation of Dolomite From Magnesite With SDS Collector: Experiments and DFT Calculation

Dolomite is the predominant calcium-bearing gangue mineral in low-grade magnesite ores. The structural isomorphism and compositional similarity between dolomite and magnesite create significant challenges in their selective flotation separation. This work employed sodium dodecyl sulfate (SDS) as a selective collector for flotation separation of dolomite from magnesite, and the mechanisms were analyzed through advanced interface characterization techniques combined with density functional theory (DFT) simulations. Experimental results demonstrated a marked separation selectivity under optimized conditions (pH 9, 1000-rpm agitation), achieving flotation recoveries of 85.97% for dolomite versus 32.95% for magnesite without depressants. DFT computational analyses revealed distinct adsorption energetics, indicating preferential chemisorption of SDS molecules on dolomite surfaces compared to magnesite. More SDS was adsorbed onto the dolomite surface and greatly increased the hydrophobicity, which was conducive to the flotation separation. SDS interacted with dolomite mainly through the sulfate group chemically bonding with the Ca site. This work proves that SDS was an effective collector of dolomite for the decalcification of magnesite ore.