Application of EIS technique to investigate the adsorption of different types of depressants on pyrite

Batch scale flotation tests are generally performed for testing effects of flotation reagents on flotation performance. This method becomes costly and time-consuming for testing a number of flotation reagents such as collectors, depressants and activators. Therefore, developing alternative lowcost, fast and sensitive methods have recently been the subject of intense research to obtain a better flotation performance. The electrochemical techniques have been used for the surface characterization of sulfide minerals. Electrochemical Impedance Spectroscopy (EIS) is one of these techniques that can provide significant information related to surface characteristics, reagent adsorption on the sulfide minerals. In this study, EIS was used as an alternative technique to the conventional batch scale flotation tests for pre-screening of various flotation reagents using two pyrite samples containing different contents of Au and As. Sodium cyanide (NaCN), sodium metabisulfite (SMBS), and a polymeric depressant Aero 7261A were tested as depressants for two pyrite samples (Sample A from a Carlintrend ore and Sample B from a Sulfidic ore from South America) having different electrochemical characteristics. EIS results showed that the effects of the sequence of addition of collector (Potassium amyl xanthate - KAX) and depressant were also investigated to evaluate the stability of depressant and collector compounds formed at the surface. The sequence of addition of the collector and depressants was significant for Sample A but not for Sample B. The results show that EIS can be used as an effective tool for testing the performance of various flotation reagents and their mixtures on sulfide minerals.