Leaching mechanism of sulfide ores in slurry electrolysis

Anodic polarization curves of sulfide mineral particle oxidation on graphite anode in slurry electrolysis have been examined to make certain of the leaching mechanism of sulfide ores in:slurry electrolysis and to build up the relationship between the anodic current density, solid content in slurry and:stirring speed. The results show that the leaching mechanism of sulfide minerals depends on the operating renditions. The anodic oxidation of mineral particles is the main reaction when no iron and copper ions exists in the slurry and at a low current density. In existence of iron or copper ions in slurry, the main anodic reaction is the oxidation of ferrous and cuprous:ions at a low current density. At high current density, Cl- ion oxidation on anode occurs and Cl-2 and HClO are produced. Sulfide leaching depends mainly on oxidation by HClO. Based on the consideration of the double layer structure and particle motion, the relationship between the anodic current density (i), solid content in slurry (c(s))and stirring speed (N-R) is determined as i = Qc(s)N(R)(2), where Q = 4 pi(2)r(2) nFk lambda, and r is the distance between stirring axis and anode surface, n is the particle number contacting with unit anodic area (1 cm(2)) in unit time, k the rate constant, lambda the proportional constant. Particle size does not affect the current density; The equation shows good agreement with the experimental results.