Selective depression of pyrite by 3-mercapto-1-propanol in Ni-Co sulfide flotation: A mechanistic study based on surface chemisorption

Efficient flotation separation of pentlandite from pyrite is central to improving the utilization efficiency of nickel-cobalt sulfide resources. In this work, 3-mercapto-1-propanol (3-MP) was employed as a selective pyrite depressant in Ni-Co sulfide flotation. The selective depression mechanism was elucidated through single-mineral, artificial mixed-mineral and real ore flotation tests, combined with contact angle measurements, adsorption measurements, Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy characterizations. Single-mineral flotation results demonstrated that 3-MP reduced pyrite recovery to 19% while maintaining pentlandite recovery steadily at 75%. In artificial mixed-mineral flotation, 3-MP significantly upgraded the nickel concentrate grade, with a nickel recovery of 85.42%. Open-circuit flotation (one rougher, one scavenger and two cleaner stages) on a real ore yielded a nickel concentrate assaying 3.40% Ni and 1.73% Co, corresponding to enrichment ratios of 5.7-fold and 5.6-fold, respectively, and the sulfur recovery to the concentrate was merely 10.07%, indicating favorable practical application potential of this reagent. Surface analyses confirmed that 3-MP chemically bonds with Fe sites on the pyrite surface via its thiol group (–SH), while exhibiting negligible interaction with Ni sites on pentlandite, thereby leaving the surface properties and collector adsorption behavior of pentlandite unaffected and ensuring its excellent floatability. This work provides a theoretical basis and technical support for the efficient separation and utilization of nickel-cobalt sulfide resources. Download: Download high-res image (176KB) Download: Download full-size image