Studied on the Non-Oxidative Leaching of Zinc Sulfide Ore in Sulfuric Acid Solutions (1st Report)

Various factors affecting the leaching rates of sphalerite in aqueous sulfuric acid solutions were examined. These factors were the iron content of the sphalerite, temperature, the after effect of various flotation agents, and the particle size of sphale- rite. Experiments were also made to compare the leaching rate of sphalerite in a hydrochloric acid solution with that in a sulfuric acid solution.The leaching rate of sphalerite linearly increased with an increase in iron content. The overall reaction of sphalerite appears to be controlled by a chemical reaction, exhibiting an activation energy of 13.7kcal/mol. The effect of potassium ethyl xanthate and pine oil on leaching rates were found to be negligibly small. On the other hand, leaching of sphalerite activated by cupric sulfate appeared to be greatly retarded. However, this decreased leaching rate of Cu-activated sphalerite was readily recovered by de-activating the sphalerite with sodium cyanide.Another important factor which affect the leaching rate was particle size. Based upon these experimental results, excess fine grinding is not effective for the leaching of sphalerite evolving hydrogen sulfide gas. The leaching rate of sphalerite in a hydrochloric acid solution without the addition of soluble chlorides was found to be slower than that in a sulfuric acid solution.