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i~ <br /> <br /> <br />- 21 - <br />There was a poor correlation between cumulative acidity and <br />percent sulfur for all samples which produced acidity (cumulative acidity <br />results are shown in Table 4 on page 22). Best fit linear, logarithmic, <br />and exponential relationships gave correlation coefficients of only <br />0.24-0.67. Relationships between cumulative acidity and neutralization <br />potential also gave low correlation coefficients of 0.18-0.63. However, <br />qualitatively, only samples with negative net neutralization potentials <br />produced acidity. <br />Heavy metals. The mean heavy metal concentration of the <br />leachates produced over the ten weeks from the humidity cell tests are <br />shown in Table 4. In general, samples which were predicted to be non-acid <br />producers according to the leachate pH, also produced heavy metals at con- <br />centrations less than 1 mg/1. An exception was the Equity-C3 and blends <br />Equity D1 and D2 which produced high concentrations of aluminum. The <br />source of the aluminum is not known, however, as the Equity-C3 was also <br />used in the blends, it is assumed that some aluminum mineral in that sample <br />was responsible. <br />Samples which produced leachates with a low pH were identified as <br />acid producers and also exhibited leachates with at least one heavy metal <br />parameter above 1 mg/1. An exception was Westmin-B, tested in 1983, which <br />produced low heavy metal concentrations. Sample Westmin-E produced a <br />leachate with indefinite pH trend, but released significant concentrations <br />of copper and zinc. As such, the heavy metal results suggest this sample <br />would be a potential acid producer, which is in agreement with actual mine <br />r drainage quality. <br />As expected, in most samples where acidity was produced with <br />resultant low pH, elevated concentrations of dissolved heavy metals were <br />' also noted in the leachate. It is also expected that a greater quantity of <br />heavy metals would be released in Stage 2 and 3 of the acid production <br />process. This view is supported by the higher concentations of heavy <br />metals found at mine sites with acid mine drainage compared to levels found <br />in leachates from our humidity cell experiments. <br />r ~~ <br />