Application and depression mechanism of sodium humate on flotation separation of molybdenite and pyrite

The depression of pyrite in the flotation separation of molybdenum-sulfur (Mo-S) mixed concentrate has become a significant issue. This study aimed to examine the process of separating molybdenite and pyrite in the presence of sodium humate (NaHA). The results of micro-flotation tests indicated that NaHA exhibited significant pyrite depression capabilities and displayed remarkable selectivity toward both pyrite and molybdenite. Real ore flotation experiments have shown that adding 22.5 mg/L of NaHA to the pulp of Mo-S mixed concentrate at a pH of 6.5, the flotation indexes achieved 46.01% Mo grade and 90.11% Mo recovery. It is noteworthy that the dosage of NaHA was significantly lower compared to the 505 utilized in the mineral processing plant. Contact angle measurements revealed that NaHA effectively increased the surface hydrophilicity of pyrite. Adsorption amount measurements, zeta potential measurements, and Fourier infrared spectroscopic (FT-IR) analysis indicated that the adsorption capacity of NaHA on pyrite was higher than on molybdenite. NaHA had a highly selective inhibitory capacity for Mo-S mixed concentrate and is an ideal separation depressant.