Abstract:The releasing behavior of heavy metals contained in primary lead slag was assessed by batch leaching and dynamic leaching methods. Effects of type of leachate and pH value on releasing behavior of heavy metals. The results show that the primary lead slag met the criterion of Category I General Industrial Solid Waste, and the equilibrium concentrations of heavy metals leached from lead slag are all below 0.1 mg/L for batch leaching tests using water and simulation acid rain as leachate. Antimony and arsenic in lead slag present high releasing character, after 12 hours, cumulative release rate of antimony and lead is 8.3 mg/m2 and 22 mg/m2 respectively. Both equilibrium leaching concentration data and dynamic release rate of heavy metals in lead smelting slag should be paid attention to evaluate its potential environmental impact.