THE USE OF MINI-HYDROCYCLONES FOR DIFFERENTIAL SEPARATIONS WITHIN MINERAL SLURRIES SUBJECTED TO BIOLEACHING

Mini-hydrocyclones were used to effect differential separation of a le ached slurry of sulphidic ore from a continuous bioleaching process. S eparations of the sulphidic ore, other non-biological solids as well a s free and attached bacteria were studied. The volumetric flow split w as found to be a power law function of the ratio of the spigot to vort ex finder diameters. The mass recovery was shown to be a function of t he outlet diameters individually, when treating a feed of the same siz e distribution. The recovery of bacterial activity was directly relate d to the mass recovery, except at high solids concentrations in the un derflow stream. Following passage through a two-stage circuit of mini- hydrocyclones, it was shown that a significant upgrading of the solids concentration could be attained, enhancing downstream processing such as cyanidation. In addition, the preferential upgrading of one stream with respect to bacterial activity (measured in terms of oxygen utili sation rate) was demonstrated. This holds potential in the recycling o f bacteria to the continuous bioleaching tanks to retain a higher biom ass concentration and improve process robustness. By recycle of a low volume stream with reduced solids concentration, plant capacity may be improved. (C) 1997 Published by Elsevier Science Ltd.