Reduction Leaching of Manganese Nodules with Sodium Sulfite in Ammonium Chloride Solution

摘要

The leaching characteristics of manganese nodules were investigated in ammonium chloride solution by using sodium sulfile as a reductant.rnExperiments were conducted in leaching of manganese, cobalt nickel, copper and iron using sodium sulfite in the ammonium chloride solution. It was found that the leaching behaviour of manganese, copper, cobalt and nickel depended on the amount of added sodium sulfite. The ratio of liquid to solid is impotant factor on the extraction of metals during leaching. The. dissolution of manganese, cobalt, nickel, copper, and iron increased with the increase in ammonium solution and that in temperature of leachant. When the leachant pH was decreased, the leachability increased for each of the metals.rnThe sodium sulfite has been found to be an effective reductant for extracting more than 95.8% of Mn, 93.5% of Ni, 98.5% of Cu, 89.1% of Co, 3.1% of Fe when leached in 5N NH_4Cl at 80℃ for 2.5hr. The dissolution rates of Mn, Ni and Cu are controlled by pore diffusion, while that of Fe is controlled by surface chemical reactons and that of Co is controlled by both the surface chemical reaction and pore diffusion process.