LIMS Study of Variables Affecting Sphalerite Flotation

"A series of flotation tests was carried out on Brunswick Mining ore with various pH modifiers (soda ash, lime, KOH) and added ions (ferric, nitrate, sulphate) in the copper lead rougher circuit. The main objective was to identify downstream effects on sphalerite activation and subsequent zinc rougher flotation. Some significant differences in zinc flotation were obtained. Most notably, soda ash and nitrate ions had a positive impact and ferric ions a pronounced negative effect on selectivity.Selected products from the flotation tests were deslimed at 400 mesh, washed with methanol, air dried, placed in teflon vials purged with nitrogen and stored at -15 degrees C. Numerous liberated sphalerite and pyrite particles were selected under a stereoscope and placed in rows on indium foil. The surface compositions of the particles were analyzed with an innovative laser probe (LIMS). The very small analysis area of the LIMS enables the surfaces of individual grains to be characterized. In addition, the rapid analysis time allows a statistically significant number of grains to be analyzed quickly.Surface lead appears to play a major role in zinc activation/flotation. Possible mechanisms are proposed to explain the variations in metallurgical performance at the different test conditions.IntroductionAlthough the bulk composition of mineral grains is an important consideration for the mineral processor it is ultimately surface composition and topography (edges and dislocations preferred sites for reactions) that control reactivity in flotation and cyanidation (passivation, encapsulation and preg-robbing). Determination of the surface properties of particles from process streams poses a particular challenge for the surface chemist for a variety of reasons, including:"