Journal of the Southern African Institute of Mining and Metallurgy
On-line version ISSN 2411-9717
TANG, M.; WEN, S. and TONG, X.. Effects on entrainment of serpentines by hydrophobic flocs of ultra-fine copper-nickel sulphides during flotation. J. S. Afr. Inst. Min. Metall. [online]. 2015, vol.115, n.8, pp. 687-690. ISSN 2411-9717. http://dx.doi.org/10.17159/2411-9717/2015/V115N8A4.
Slime coating is one of the most common ways for serpentines to contaminate metallic mineral concentrates during traditional flotation of coarse sulphide particles. This could pose quite a complicated and challenging problem in the case of some types of low-grade and finely disseminated Cu-Ni ores bearing high serpentine contents. This is the case for the copper and nickel sulphides from the Yunnan Mine, China. Previous batch flotation tests of this ore resulted in satisfactory recoveries of 86.92% Cu, 54.92% Ni, and 74.73% Pt+Pd, and concentrate grades of 4.02% Cu, 3.24% Ni, and 76.61 g/t Pt+Pd. However, the MgO content in these concentrates was more than 19%. In the current study, microflotation tests and settling rate tests were introduced to investigate the effects of a combination of strong collectors (a 2:1 weight ratio of butyl xanthate and butyl ammonium dithophosphate) on entrainment of serpentines in metallic mineral concentrate, as well as visual observations of the concentrates in suspension using still photography. All test results indicated the presence of serpentines entrapped in the hydrophobic flocs that resulted from these collectors, even with the use of effective gangue depressants. These strong collectors are used to flocculate the ultra-fine sulphides by forming loose and 'fluffy' hydrophobic flocs. However, these hydrophobic flocs may also be able to load or entrap some serpentine slimes into the concentrate, and this entrained serpentine could be harder to remove by using depressants or intensified conditioning than serpentine slime coating on the particle surfaces.
Keywords : sulphide flotation; serpentine; hydrophobicity; ultra-fine; entrainment.