Flotation separation of pyrrhotite from magnetite using sodium fluosilicate (Na<sub>2</sub>SiF<sub>6</sub><sub></sub>) as a selective activator

Pyrrhotite and magnetite exhibit similar magnetic properties and oxidation susceptibility, posing significant challenges to their effective separation. This study investigated the flotation separation of pyrrhotite and magnetite using sodium fluorosilicate (SF) as an activator and xanthate as a collector. Single-mineral flotation tests demonstrated that SF effectively activated pyrrhotite flotation, enhancing its recovery rate. For artificially mixed ores with an initial sulfur grade of 19.79%, flotation achieved a concentrate with 39.32% sulfur content and 46.64% recovery, realizing efficient separation. Under the conditions of sulfur and iron grades of 2.60% and 61.34% respectively in the real ore feed, a sulfur concentrate with a yield of 25.80%, sulfur grade of 9.15%, and sulfur recovery rate of 90.86% was obtained, as well as an iron concentrate with a yield of 74.20%, iron grade of 63.08%, and iron recovery rate of 76.30%. This successfully achieved the objective of "increasing iron content and reducing sulfur content." Solution chemistry analysis, contact angle measurements, FTIR, and XPS investigations revealed the adsorption mechanisms of SF and xanthate on mineral surfaces. Results indicated that both SF and xanthate selectively adsorbed only on pyrrhotite surfaces. Furthermore, SF facilitated exposure of additional active sites on pyrrhotite, thereby promoting xanthate adsorption. These findings provide critical insights into the surface activation mechanism enabling effective pyrrhotite-magnetite separation.