Prediction of acidic drainage and accompanying metal releases from unsegregated pyritic uranium mill tailings based on effluent chemistry and post leaching sample mineralogy

摘要

Unsgregated pyritic uranium mill tailings from Elliot Lake, Ontario, with and witout limestone amendment, were usjbect to column leaching experiments for the puroses of predicting the onset of acidic drainage and the magnitude of metal and radionuclide release under various treatment and control strategies. The unamended tailings produced acidic drainage after approximately on and a half year. The tailings mixed with various grain-sized limestione did not produce acidic drainage during the study period. The tailings fine limestone displayed the least amounts of pyrite loss whereas those without limestone amendment had the greatest pyrite losses. Predicted onset of acid generation varied from 16 to 75 years for the top section and in most case greater than 100 years for bottom sections of the unsegregated tailings with limestone amendments. Unsegregated tailings mixed with fine- and very fine-graind limestone proved to be the most effective in controlling or delaying the onset of acidic drainage under unsaturated conditions.