THE EFFECT OF SIZE SEPARATION BY CYCLOSIZING AND SEDIMENTATION DECANTATION ON MINERAL SURFACES/

Particle size dramatically influences the flotation behaviour of galen a, The part that differences in surface chemistry play in this effect is not yet clear, Experiments were designed to examine the surface che mistry of size fractions prepared from lead rougher feed pulp from Abe tfoyle's Hellyer operation, However, the effects of the sizing techniq ue employed on the surface properties of the particles were found to b e significant, Lead rougher feed was sited using two commonly availabl e techniques: cyclosizing and sedimentation/decantation. Similar size fractions prepared by the two methods were examined using bulk assays (XRF) in conjunction with scanning electron microscopy (SEM) and x-ray photoelectron spectroscopy (XPS) to identify differences in aggregati on and surface characteristics. The observations show that the cyclosi zer produced particles free of attached fine particles (i.e.slimes coa tings) due to the high shear environment. The sedimentation/decantatio n process yielded particles covered with attached fine particles us sh ear rates were essentially zero. The high shear present in the cyclosi zer resulted in surfaces that were sulphide rich, whilst the sedimenta tion/decantation procedure, over periods up to 24h, produced surfaces that showed high levels of oxidation. (C) 1997 Elsevier Science Ltd.