Abstract: To address the difficulty in separating zinc minerals from calcite in a high-calcium,low-grade zinc oxide ore from Yunnan,flotation tests were conducted based on process mineralogy studies,using sodium carbonate as a dispersant,sodi um sulfide as a sulfidizing agent,sodium hexametaphosphate as a depressant,and a cationic-anionic combined collector com posed of modified oxygen-containing amine KOX-3 and phosphonic acid-containing anion KX-2.The ore contains Zn of 5.56% with an oxidation rate of about 91%;The main valuable minerals are smithsonite and hemimorphite,while the gangue is predominantly calcite (51.65%).Condition tests determined the optimal reagent regime as:Na2 CO3 of 3 000 g/t,Na2 S of 10 kg/t,sodium hexametaphosphate of 1 000 g/t,KOX-3 of 500 g/t,and KX-2 of 100 g/t.Under a grinding fineness of 80% passing 0.074 mm,a closed-circuit flowsheet was adopted,in which the rougher 1 concentrate was cleaned twice (with the cleaner 1 middlings returned to rougher 2),and the rougher 1 tailings were subjected to one roughing,two scavenging,and three cleaning stages;The two concentrate streams were combined to yield a final zinc concentrate with a grade of 22.87% Zn and a recovery of 80.35%.The results indicate that this flotation scheme with the cationic-anionic combined collector features a simple reagent regime and a well-structured flowsheet,effectively achieving separation of zinc minerals from calcite. It can provide a technical reference for the efficient recovery of similar high-calcium zinc oxide ores,and is of practical significance for unlocking the potential of complex refractory zinc oxide resources in China and reducing external dependence on zinc.

Key words: zinc oxide ore,smithsonite,calcite,cationic-anionic combined collector,flotation,sulfidization-amine method