THE FLOTATION OF FINE PYRITE USING COLLOIDAL GAS APHRONS

Fine mineral flotation is known to be problematic, however there is ev idence that flotation performance is improved by the use of fine bubbl es. In this work, a comparison is made between the flotation performan ce of two flotation systems; a conventional batch flotation cell and f lotation using a spinning disc impeller as is used to generate very sm all bubble suspensions called colloidal gas aphrons (CGA's). The compa rison of the CGA and the standard impeller was made using an artificia l ore consisting of gravity concentrated pyrite from Durban Roodepoort Deep (South Africa) and quartz from Delmas (South Africa) finer than 38 microns. The collector was sodium n-propyl xanthate, the frother Do w 400. The comparison of the flotation performance was made at the fol lowing conditions; pH 4 and 8 and copper sulphate addition nil and 50 g/ton. The froths found in the two systems had significantly different structures. The CGA impeller yielded a froths surface with considerab ly larger bubbles and a wider distribution of bubble sizes than the co nventional batch cell. The CGA float yielded higher grades (50% sulphu r) than the conventional float (35%), although the flotation rate was somewhat lower. The results obtained indicate that this flotation syst em may have application for the selective recovery of finely ground mi nerals.