Anodic process of stibnite in slurry electrolysis: The direct collision oxidation

Mineral oxidation leaching in the anode area is the key step in slurry electrolysis. By adopting the slow linear potential scanning method during slurry electrolysis, this study investigated the steady-state polarization curve of a pure stibnite mineral on a graphite anode. In addition, the influence of the mineral particle size, liquid-solid ratio, stirring speed, and temperature on the collision oxidation of the mineral with the anode was studied. Based on the different oxidation reactions, the potential range can be divided into three intervals: the low-potential interval with a potential lower than 0.75 V, an intermediate-potential interval with a potential within 0.75-1.2 V, and a high-potential interval with a potential higher than 1.2 V. The collision oxidation of the mineral with the anode occurred in all three intervals. The oxidation of Sb(III) also appeared in the intermediate- and high-potential intervals, and chlorine evolution occurred in the high-potential interval. Therefore, the low-potential interval was determined to be a suitable potential interval for the slurry electrolysis process. In the low-potential interval, the particle size, liquid-solid ratio, and stirring speed had little effect on the oxidation rate of the minerals. As the temperature increased, the stibnite oxidation rate and exchange current density increased. Overall, the direct collision oxidation rate of stibnite was relatively low and the current densities under all the investigated conditions were lower than 0.4 mA-cm(-2). This indicates that it is difficult to realize industrial production while relying solely on this process. (C) 2021 The Chemical Industry and Engineering Society of China, and Chemical Industry Press Co., Ltd. All rights reserved.