1989-11-22_REVISION - M1988112 - Laserfiche WebLink

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- 14 - 3 RESULTS ANO DISCUSSION 3.1 Acid/Base Accounting A potential acid generating material is defined as any rock or earth material having a negative net neutralization potential of 5.0 tonnes of calcium carbonate equivalent or more per 1000 tonnes of material (17). According to this criteria, 15 of the 22 samples tested exhibited a poten- tial to generate acid mine drainage (Table 3). Five samples would not be expected to produce acidic drainage, while the results of two tests were inconclusive since the net potential was between zero gad the 5 tonnes CaC03/lODO tonnes criteria. The author or staff have conducted site inspections at all of the sampled mines in British Columbia and Yukon. Acid mine drainage has been ^ found at a number of these sites. The formation of acid mine drainage was i correctly predicted by the acid/base accounting method in all but three I cases - the two inconclusive results referred to previously and one incor- rect prediction. The incorrect prediction was made for the C2 - Scottie waste rock sample. Previous acid/base accounting tests by other C researchers (26) have also indicated that the Scottie rock has a potential to generate acid mine drainage. However, no acidic drainage has been found ~ at that mine site after about 4 years of operation. 3.2 Humidity Cell ~. No criteria have been developed to define the poten- tial for acid mine drainage using the humidity tell method. The leachate pH results from most of the humidity cell experiments fall into 3 categories: 1) samples which produced acidic leachates or leachates with falling pH throughout the test; 2) samples which produced alkaline leach- leachates or; 3) samples which produced leachates with rising pH throughout ' the test. The first category is considered evidence of a potential acid mine drainage producer and the last two Categories, non-acid producers.