• Calcium hypochlorite selectively depresses bismuthinite and pyrite while improving flotation indicators for molybdenum and bismuth concentrates compared to sodium sulfide.
• Using calcium hypochlorite as a depressant significantly reduces flotation reagent dosage and lowers the chemical oxygen demand (COD) of tailings wastewater.
• Mechanistic analysis reveals that calcium hypochlorite forms BiOCl precipitation on bismuthinite surfaces, hindering collector attachment and enabling selective separation.
• The substitution of sodium sulfide with calcium hypochlorite offers a cleaner and more sustainable route for processing low-grade molybdenum-bismuth ore in industrial applications.