Balancing collecting and foaming capacity of flotation collector to improve the enrichment efficiency of nickel sulfide ore

The effective flotation separation of pentlandite from serpentine is of critical importance to the beneficiation of pentlandite, a challenging task in the realm of sulfide mineral processing. Conventionally employed dithiophosphate (DTP) collector suffered from entrainment from its strong foaming capacity and weak collecting selectivity. In this study, we aim to address this issue by employing a new phosphonodithioate scaffold and leveraging its intramolecular electronic effect. A series of phosphonodithioates with variable alkyl chain length were synthesized and their flotation results demonstrated superior collecting capacity and selectivity. A foaming test on the best performing O-propyl S-hydrogen (4-methoxyphenyl) phosphonodithioate (PHMP) collector indicated that the entrained rate (eg) of serpentine was only 0.2 and the foaming amount was only one-tenth of that of traditional dithiophosphate collector. The adsorption data indicated that PHMP had a stronger adsorption affinity for pentlandite than DTP. The FTIR and XPS results suggested that the interaction of PHMP with pentlandite may be dominated by chemisorption, and DFT calculations confirm that electron-donating substituents improve the flotation capture capacity of PHMP for pentlandite. The combined experimental and theoretical investigations revealed the role of intramolecular electron effects in the enhanced flotation performance of phosphonodithioates.