Electrolysis Oxidation of Chalcopyrite and Molybdenite for Selective Flotation

Abstract

Electrolysis oxidation of chalcopyrite and molybdenite was investigated, via various electrochemical methods, with the aim of realizing selective otation of these minerals. Result of potential polarization indicated that oxidation via electrolysis affected only the chalcopyrite surface, owing mainly to the difference in conductivity of these minerals. Also measurements of contact angle after electrolysis indicated that contact angle of chalcopyrite selectively decreased whereas that of molybdenite did not decrease drastically. XPS analyses after electrolysis indicated that chalcopyrite peak decreased whereas iron oxyhydroxide (goethite) and iron sulfate increased, it suggests that these oxidation products covered on the surface of chalcopyrite. On the other hand, molybdenite peak is similar after electrolysis except for molybdenum oxide/ oxygen with molybdenite can be seen for oxygen peak. From these results and general knowledge that sul de hydrophobicity and sulfate/ oxyhydroxide hydrophilicity, it can be explained that with electrolysis oxidation, hydrophilic oxihydroxide and sulfate covered on the surface of hydrophobic chalcopyrite then chalcopyrite surface became hydrophilic. On the other hand, molybdenite surface keep hydrophobic since its dif culty of oxidation and it is dif cult to stay molybdenum oxide on the surface due to its soluble property. These results revealed that chalcopyrite was selectively oxidized and, hence, selective otation of chalcopyrite and molybdenite was possible. This electrolysis oxidation methods were compared with those governing other oxidation treatments.

Advances in Selective Flotation and Leaching Process in Metallurgy

“…After oxidation treatments, chalcopyrite is aggressively oxidized, resulting in a decrease in CuFeS 2 floatability due to the formation of hydrophilic oxidation products on its surface [13,69,74,75,78].…”

“…MoS 2 was also oxidized, and on its surface, oxidation products (e.g., MoO 3 ) were formed; however, MoO 3 is highly soluble under alkaline conditions, so its effect on MoS 2 floatability becomes negligible under typical Cu-Mo flotation conditions (pH > 9) [13,74,75,78].…”

A Review of Recent Advances in Depression Techniques for Flotation Separation of Cu–Mo Sulfides in Porphyry Copper Deposits

“…The electrical resistivities of chalcopyrite and molybdenite are 234 Ω and 1.2-1.5 MΩ, respectively, which means that chalcopyrite is more electrochemically active than molybdenite is [78]. From the difference in the minerals' electrical resistivity, Miki et al [78] attempted to apply electrolysis, a technique that applies a fixed potential in which mineral undergoes oxidation process(es) to selectively render the chalcopyrite surface hydrophilic. Anodic polarization results at an applied potential of 1.2 V showed that a high current density of chalcopyrite electrodes (around 0.4 mA/m 2 ) was observed, indicating that the oxidation of chalcopyrite was actively progressed, as shown in the following equation:…”

Effect of Sodium Sulfite on Floatability of Chalcopyrite and Molybdenite

“…Afterwards, contact angle measurements were carried out using a goniometer (Dropmaster 300, Kyowa Interface Science Co., Ltd., Saitama, Japan). The contact angle was measured using the bubble captive method following the procedures described in previous work [17,18].…”