Abstract

The floatability of sulphide minerals is dependent of the potential difference of a mineral-solution interface, which is referred as pulp potential (Gotepke, F., 2002; Moslemi, H., Shams, P., Habashi., 2011; Woods, R., Gardner, J., 1979). It is well known that mineral floatability can be manipulated just by changing the oxidizing and reducing pulp conditions in such a way that the measured potentials determine whether or not the mineral will float. In a mineral interface in equilibrium with a pulp solution a mixed-potential condition should prevail, which mean that the sum of all partial oxidation currents must equal the counterpart sum of all reduction currents. Thus, the mixed potential (Ahmad, Z., 2006) of the partial electrochemical reactions in a mineral-solution interface is a unique value that indicates the predominance of a particular situation (Labonté, G., 1999), which for flotation is associated to a hydrophobicity/hydrophilicity balance on a mineral surface. Thus, the electrochemical potential is an important parameter in controlling the recovery and selectivity of sulphide minerals during flotation (Moslemi, H., Shamsi, P., Alimohammady, M., 2012). A noble metal electrode is usually used as a working electrode to measure pulp potential (Woods R., 2003). This in flotation systems seems inadequate since different electrode materials can yield different potential values in the same solution (Rand, D., Woods, R., 1984), and from the basic principles of flotation, the desired potential to be monitored would be the mineral potential, not the solution. This suggests that an electrode constructed from the mineral being concentrated should be the most appropriate for potential measurements rather than noble metal electrodes (Gotepke, F., 2002). Unfortunately, not always is possible to find the mineral massive to make the work electrode. When a mineral massive sample is not available for electrochemical studies, the preparation of an electrode using an adequate support for solid particles is an essential preliminary step (Hu, Y., Wei, W., and Wang D, 2009). This material support must be both a good electrical conductor and an effective adhesive for particles. In this work, a novel flow cell suitable for electrochemical flotation studies is presented. Electrochemical measurements of mineral in seawater were made using two mineral samples as found in mineral deposits in Northern Chile. Each sample was subdivided in a powder a cylindrical massive subsamples to prepare two different types of working electrodes.