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whole Rock Analysis. The subsplits of each <br />sample designated for whole rock analysis <br />were further pulverized to pass 125 microns <br />and were analyzed for total sulfur content <br />(a measure of the pyrite present in the <br />sample) and neutralization potential (re- <br />flecting the amount of carbonate material). <br />Total sulfur contents were analyzed in a <br />LECO induction furnace and automatic sul- <br />fur titrator. Values are expressed as per- <br />centages on a weight by weight basis. <br />The neutralization potential (NP) is a <br />measure of the amount of a standard hydro- <br />chloric acid solution that is necessary to <br />neutralize a given amount of pulverized <br />cock sample. The value is converted to an <br />equivalent amount of calcium carbonate which <br />will generate the same amount of neutrali- <br />zation. The NP is therefore the theoretical <br />amount of alkalinity that the rock will <br />ultimately be expected to prod uce.S The NP <br />value is expressed as milligrams of calcium <br />carbonate equivalent per gram of sample. <br />The NP will usually overestimate the <br />capacity of a rock to produce alkalinity <br />because it fails to take into account the <br />kinetics of the natural reactions. Rocks <br />in the field are not so finely ground, nor <br />are they heated as the samples are in the <br />lab. <br />Results and Discussion <br />The 11 samples used in the study had <br />a different sulfur and neutralization po- <br />tential value and produced a spectrum of <br />leachate qualities varying from alkaline <br />acid. To facilitate the discussion, only <br />RUYSER 1 <br />O <br />u <br />U <br />P <br />O <br />E <br />a <br />0 <br />U <br />W <br />r <br /><_ <br />U <br />J <br />four of the 11 samples, which were deter- <br />mined to be representative of the trends <br />produced by the remaining samples, will be <br />presented. <br />The plots for the four samples are <br />shown in Figures 2 through 5. There was a <br />strong correlation between the specific con- <br />ductance values and the sulfate content, <br />and both trends mimicked each other; as did <br />the pH and the leachate acidity. For these <br />reasons the pH and specific conductance <br />values are not shown. <br />Sample No. 1 had a sulfur content of <br />2.1 percent and an NP of 31. As Figure 2 <br />shows, this sample did not produce acidity, <br />there was no increase in sulfate and all <br />leacha tes were nonacid. In fact this sam- <br />ple, because of the high NP, neutralized <br />the acidity of both the acid rain and the <br />acid mine drainage. The dashed line in <br />Figures 2 through 5 represents the acidity <br />of the synthetic acid mine drainage. <br />Clearly, the leacha to from the sample <br />leached with acid mine drainage was non- <br />acid, indicating neutralize talon had taken <br />place. Thus, although the pLtential of <br />this sample to produce acid was high (2.1 <br />percent sulfur) the presence of calcareous <br />material not only neutralized the acidity <br />introduced, but as shown by the lack of <br />increase in sulfate, inhibited the oxidation <br />of the pyrite. <br />Sample No. 3 had a lower potential to <br />produce acidity (0.2 percent sulfur) and a <br />lower NP (19). The acidities of the <br />to leachates produced were all lower than the <br />acid concentrations introduced into the <br />SAMPLE RUYBER S <br />O <br />v <br />u <br />• <br />P <br />0 <br />0 <br />P <br />E. <br />- Yne I <br /> P <br />~.1 %s o <br />31 NP ~ <br /> <br /> E <br />TIME (wwk~~ <br />Figure 2. Plot of leachate acidity and <br />sulfate concentrations versus time for <br />sample 1. <br />W <br />H <br />~_ <br />U <br />J <br />ua, <br />• ~,rM4 4 <br />•~wb.1,LMYY~>rT <br />aw.u P: <br />we.~.. 1.."'+w.' <br />biO~M., L.aNlw <br />~ 4W1 <br />I[Y,• OI: <br />~vl Lr Y,. <br />L..e <br />0.4 X S <br />es wv <br />i <br />.. , <br />f <br />e , • a • • • , • • ,e n 9 n w u ~. n <br />TIME (w Hk~~ <br />441 <br />Figure 3. Plot of leachate acidity and <br />sulfate eoneen[ratio ns versus time for <br />sample 3. <br />