1989-11-22_REVISION - M1988112 - Laserfiche WebLink

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~~ - 3 0 - and negative net neutralization potentials produced acidity. Results support the use of the acidJbase accounting procedure for pre dieting acid mine drainage formation but, suggest there is only a poor rela- tionship between the magnitude of the acid/base accounting result (net neutralization potential) and the amount of acidity produced during the initial stages of the AMD process. 5) Thiobacillus ferrooxidans did not appear to play a significant role in initiating the acid generation process in these limited duration tests. Further more detailed work on a wide range of samples, with acclimated bacteria over a longer test period, are required to substantiate this j finding. 6) Decreasing sample particle size increased the pyrite oxidation rate in an exponential relationship. Acidity production was significantly greater for the smaller size particles and was linear with respect to exposed surface area. Differences in particle size, therefore„ must be considered in acid mine drainage predictions. 7) The pyrite oxidation rate of blended samples could be calculated from the weighted sum of the rates for the components of the blend. The net neutralization potential of the blends agreed with the alkaline leachate produced from the humidity cell experiments. Blending on at least a small scale, therefore, may be an effective method for '+nhibi- ting acid mine drainage by controlling the initial acidificatioro step. However, the effect of different particle sizes of acid producing and consuming materials, uneven blending, and channelization of groundwater flow through dumps should be examined in any field applications. Further experiments of longer duration on large scale test dumps are ~ also required to confirm this finding. 8) Both the acid/base accounting and humidity cell techniques are useful for predicting the potential for acid mine drainage. in many cases,