Abstract: To solve the problem of continuous decrease of beneficiation indexes with the transfer from open-pit mining to underground mining of residual ores in Changba Lead-Zinc Mine, and in view of the characteristics of its sulfide-oxide mixed lead-zinc ore, research was made on a new flotation reagent regime adopting sodium sulfide for activating lead oxide, an efficient collector D421 for enhancing lead flotation, and sodium silicate and MP for depressing silica in zinc cleaning.Both its lab and industrial tests gained satisfactory results.Since its use in the production, the beneficiation indexes of this mine have been fully improved, which can bring an over 37 million yuan additional economic benefit per annum.

Key words: Sulfide-oxide mixed lead-zinc ore, Flotation reagent regime, Efficient collector D421, MP depressor for silica