Diavik waste rock project : characterization of particle size, sulfur content and acid generating potential Smith, Lianna J.D.; Amos, Richard T.; Chi, Xiatong; Blowes, David W.; Stastna, Marek; Smith, Leslie; Sego, David C.
The heterogeneous distribution of physical and geochemical characteristics of waste rock has a major influence on the acid generating potential of the rock. This includes controlling the rate and extent of water, gas and thermal transport processes, which affect the rate of oxidation and leaching of oxidation products. Two experimental waste rock piles at the Diavik Diamond Mine have been characterized in terms of particle size ranging from boulders to fines, sulfur content of the bulk rock and individual size fractions of the rock, and the acid generating potential of the rock. The development of a digital image processing (DIP) technique provides a means of characterizing spatial distribution of the > 10 cm to boulder size fraction of waste rock. Combining the DIP techniques with traditional sieve analysis of the fine fraction provides a full-spectrum grain-size distribution of the waste rock. The average sulfur content of the two waste rock piles was determined to be 0.035 wt. % S (Type I pile) and 0.053 wt. % S (Type III pile), and both rock types are determined to be potentially acid generating using standard acid-base accounting methods. Detailed analysis of the fine fractions for both rock types suggests that the acid generating potential of the waste rock is not evenly distributed among particle sizes. Although both sulfur content and neutralization potential increase with decreasing particle size, overall acid generating potential also increases with decreasing particle size. This research provides a greater understanding of the spatial distribution of rock characteristics that control the generation of acidic leachate in waste rock piles.[All papers were considered for technical and language appropriateness by the organizing committee.]
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