Advanced collector-free flotation of typical sulfide minerals using a novel heterocyclic depressant

Abstract

Molybdenite is the main source of molybdenum which is widely used in industry. Due to its excellent natural floatability, it is urgent to develop selective depressants, which is the key to achieve the flotation separation of molybdenite from other sulfide minerals such as chalcopyrite, galena and pyrite. In this work, a thiazole depressant 2,4-thiazolidinedione (CSD7) is developed based on the selective chelation of heteroatoms to Cu2+, Pb2+ and Fe2+. The flotation tests of single and mixed minerals confirm that CSD7 can achieve an efficient separation of molybdenite from chalcopyrite, galena and pyrite in a collector-free flotation system. Under the concentration of CSD7 with 5 × 10−4 mol/L and pulp pH of 7, the grades of molybdenite concentrate are higher than 50%, and the corresponding recoveries are higher than 80%. The Fourier Transform Infrared Spectroscopy (FT-IR) and electrochemical tests indicate that CSD7 can adsorb onto the surfaces of chalcopyrite, galena and pyrite, but can hardly adsorb onto the surface of molybdenite. CSD7 chelates with Cu2+, Pb2+ and Fe2+ on the surfaces of chalcopyrite, galena and pyrite through the four-membered ring formed by the bonds of −S−M2+ and =O−M2+. Moreover, the contact angle measurements also manifest that CSD7 selectively strengthen the hydrophilicity of the surfaces of chalcopyrite, galena and pyrite rather than molybdenite. The simply synthesized, low-cost and green CSD7 has a great potential in the separation of molybdenum from other sulfide minerals in flotation plant.