Synergistic Surfactant-Collector Effects on Pyrite Desulfurization in Iron Ore Concentrate

Pyrite is the main sulfide mineral responsible for the increased sulfur content in magnetite concentrates at the Golgohar iron ore complex, which negatively affects steel production quality. Reverse flotation using xanthate collectors and methyl isobutyl carbinol (MIBC) as frothers is commonly used for desulfurization. This study investigates the synergistic effects of combining surfactants such as sodium lauryl ether sulfate (SLES) as a filter aid with collectors in flotation. The focus is optimizing reagent dosages to enhance pyrite removal efficiency while minimizing impacts on iron recovery and filtration performance.

Laboratory flotation experiments were conducted on magnetite concentrate samples (64.94% Fe, 24.77% FeO, 0.71% S) using a Central Composite Design (CCD) via Design-Expert software. Key variables included collector (0-164 g/t), frother (0-87 g/t), and surfactant (0-150 g/t) concentrations. Pulp density was 30% solids, with conditioning times of 2 min for collector/surfactant and 1 min for frother. Floated and non-floated fractions were weighed, assayed for Fe, FeO, and S, and evaluated for separation efficiency, recoveries, and concentrate quality. Complementary filtration tests assessed cake moisture.

Adding 75 g/t SLES improved desulfurization, raising sulfur separation efficiency from 52% to 70.1% and recovery from 53% to 72%, while reducing concentrate sulfur from 0.34% to 0.20%. Iron recovery decreased slightly by 0.8%. Optimal dosages: 80 g/t collector, 40 g/t frother, 75 g/t SLES, enabling 40% collector and 62% frother reductions. SLES (HLB=40, MW=496.7 g/mol) showed superior selectivity and power over MIBC, with 2% average moisture reduction in filtration.

The SLES–xanthate synergy enhances pyrite hydrophobicity via co-adsorption, charge screening, and lowered critical micelle concentration, promoting efficient flotation without disruptions. Findings support integrated surfactant use in industrial circuits, with potential for scale-up and alternative surfactants exploration.