Upgrading of talc-bearing copper-nickel sulfide ore by froth flotation using sodium phytate as depressant

Copper-nickel sulfide ores, as important sources of copper and nickel metals, always have large amount of claytype gangue minerals like talc. In this work, selective flotation of copper-nickel sulfide ore was achieved by using a selective depressant of sodium phytate. Microscale flotation results show that sodium phytate can selectively and effectively depress talc flotation, but has a minor effect on the floatability of chalcopyrite and pentlandite. In batch-scale flotation tests of feed ore, containing 0.35% Cu, 0.68% Ni and 24.57% MgO, potassium butyl xanthate was employed as the collector in rougher (200 g/t), scavenger-1 (100 g/t), scavenger-2 (50 g/t) and scavenger-3 (25 g/t), and sodium phytate depressant was used in rougher (300 g/t) and cleaner-1 (100 g/t) stages of closed-circuit flotation to obtain a concentrate containing 2.66% Cu (79.7% recovery), 5.38% Ni (83.01% recovery), and only 6.39% MgO. The contact angle analysis showed that sodium phytate significantly improved the hydrophilicity of talc, but it only slightly increased the hydrophilicity of chalcopyrite and nickelpyrite. The FTIR and XPS tests showed that chemisorption of sodium phytate occurred on talc surface by the interaction between P-O/P--O and Mg active sites. This work indicates that sodium phytate has strong potential as an inhibitor for the selective separation of talc from copper-nickel sulfide ores.