Direct acid Leaching of zinc from Marmatite ores 2 Kinetics of Autoclave Leaching of Synthetic ${\beta}$-ZnS

The influence of impurities contained in Marmatite ores on leaching of zinc was investigated. The zinc sulfide having the same crystal structure of natural Sphalerite was prepared by heating the zinc sulfide chemically precipitated, at in nitrogen atmosphere. The activation energy of the sample was 25.8 kcal per mole in the leach test when oxygen partial pressure was 5 atm. and the value was exceedingly high compared to that obtained in Marmatite ores. Synthetic zinc sulfides added with small amount of each impurities were treated in same procedure. As a result, it was found that the leaching velocity was accelerated sharply when about 1 percent of was blended to the sample. Larger amount of iron has also same effect but the effect was minor compared to the copper. The other impurities indicated no appreciable catalytic action.