Molybdenum is primarily obtained as a by-product of porphyry copper ores processing by flotation. The process produce a bulk Cu/Mo concentrate followed by the separation of molybdenite. Plant results have consistently shown, for bulk Cu/Mo concentrates, significantly lower Mo recoveries. Several factors have been proposed to explain this different metallurgical response: particle morphology, as molybdenite anisotropy results in platelet shaped fragments that exposes hydrophobic inert faces and hydrophilic reactive edges (ratio of exposed areas of faces and edges defines particle hydrophobicity); cell hydrodynamics, as thin particles align along liquid streamlines facing rising bubbles with the minimum hydrodynamic diameter (normally edges), reducing bubble-particle collisions and contact frequency with particle hydrophobic surfaces; reduction of hydrophobicity, by adsorption of positive ions at edges, and slimes coating after these ions bridge fine gangue particles; and low froth recovery, as flat and elongated molybdenite particles on the surface of bubbles are effective breakers of films between bubbles of approaching bubble-particle aggregates. These factors suggest that for a given feed and chemistry, the Cu/Mo recovery will depend primarily on the hydrodynamic conditions created by the flotation machine in use. Generation of small bubbles by contacting air and mineral pulp under highly turbulent conditions, features of the co-current air-pulp flow in the downcomer of Jameson cells, is the most promising option for flotation of molybdenite particles. This communication documents a case study run in a copper concentrator to demonstrate that a Jameson cell can produce bulk Cu/Mo concentrates with high recovery for both species. The results showed that target Cu grade was reached with higher Cu recoveries in the Jameson cell than in columns, and that the same Cu and Mo recovery were obtained in the Jameson cell. The significant improvements in Mo metallurgical performance were attributed to the unique hydrodynamic conditions generated in a Jameson cell.
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