Electrochemical Oxidation Leaching of Gold-Arsenic Concentrates and Sulfide Concentrates 1

In recent years, due to the material composition of complex sulphide concentrates and strengthen environmental protection work, prompting the hydrometallurgical treatment of sulphide concentrates growing up. After extensive research, many new process options have emerged. For gold - leaching pyrite and arsenopyrite and arsenic concentrate fines umbrella is associated, wherein the electrochemical oxidation is a method of.

Arsenic pyrite and pyrite are minerals that are relatively chemically stable and are not suitable for direct leaching with acid solutions and alkaline solutions. They can only decompose in the presence of oxidants (because they can change their potential in the positive direction). The electrochemical conditions for the oxidation of arsenic pyrite and pyrite in acidic and alkaline solutions were investigated. The results demonstrate that the chemical stability of arsenopyrite and pyrite depends to a large extent on the nature of the solvent used. The most advantageous conditions for oxidizing these two minerals can be caused in an alkaline solution. When oxidation is carried out in this solution, the change in electrode potential is minimized and the required power consumption is the lowest. In this case, due to the different electrochemical conditions for the oxidation of arsenopyrite and pyrite, it is possible to preferentially leach the most difficult arsenopyrite when processing the sulfide concentrate.

When electrochemically leaching gold - arsenic concentrate, it is most desirable to use a caustic soda solution. Caustic soda is the cheapest of all alkalis, and the caustic soda solution is highly conductive. The secondary process of transferring gold into the liquid phase does not occur with the caustic soda solution, which is produced when the ammonia solution and the chloride solution are used. Gold dissolution can cause redistribution of metal between the liquid phase, and the precipitate was leached cathode, with the result that the lower - gold recovery step process is more complex;

Kinetic studies on the electrochemical leaching of arsenopyrite and pyrite with caustic soda solution indicate that the temperature exceeds 50 °C The leaching process is carried out within the kinetic range. At 50~ 80 °C Within the range, depending on the oxidation conditions, the calculated activation energy of the mineral oxidation is 6.1 to 14.4 kcal / gram for arsenic pyrite and 8.1 to 16.3 for pyrite. Thousands of calories per gram. At lower temperatures, due to oxidation products formed on the mineral surface. As the density increases, the leaching process takes place in the internal diffusion zone. The oxidation kinetics on the single crystal was studied by artificial polarization method, and the equation is as follows;

Temperature is 70 °C The reaction rate constant calculated at the time is: