ACTIVATION OF SPHALERITE FLOTATION IN THE PRESENCE OF LEAD IONS

During the differential flotation of polymetallic sulphide ores, some selectivity problems may appear. it is sometimes difficult to prevent the collection of the sphalerite in the lead and/or copper concentrates. Laboratory batch flotation tests performed respectively on pure minerals and on natural ores have shown that the main factors affecting sphalerite collection may be related to sulphide oxidation. This suggests that sphalerite collection is the consequence of its activation by metallic cations released by the sulphides present. These tests show that: (1) activation is fast, and even almost instantaneous when the sulphides are oxidized. Otherwise, it depends on the time of aeration of the pulp. (2) Large amounts of cations are involved: they vary with the degree of oxidation of the sulphides, pH and the presence of pyrite. With the use of ESCA, it has been shown that the lead activating the sphalerite may occupy up to 30% of the cationic sites of the first ten atomic layers.