Abstract: The influence of the environmental factors on the release of Cu²⁺，Zn²⁺，Pb²⁺，Cr³⁺ out of the tailings of a copper sulfide mine was investigated by static soaking experimental method through altering the temperature of the soaking system, upper layer solution and ore sample layer height and ore layer cross-section and blowing air into the solution surface and adding flotation agent to the system. It is deduced from the test results that, in terms of heavy metal ion release, the environmental danger from the sulfide ore tailing reservoirs in North China could be more serious than that in South China, and that in summer more serious than in winter. The larger the accumulated water depth or area covering the tailings in the reservoir, the easier the heavy metal ions will be released; the thicker the tailing deposited in the reservoir, the easier Zn²⁺ will be released while the more difficult Pb²⁺, Cu²⁺ and Cr³⁺ will be released. The great disturbance to the water surface of the tailing reservoir may enhance the release of heavy metal ions and the flotation reagent will also affect their release but the conditions are rather complex.

Key words: Sulfide mine tailings, Heavy metals, Ion release, Environmental factors, Static soaking