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Acid Base Accounting(ABA) <br /> ABA is a geochemical analytical procedure that assesses the acid-generating potential (AGP)and acid- <br /> neutralizing potential (ANP)of rock samples,along with the various sulfur species content of the <br /> material being analyzed. Because it provides no information about the rate at which acid generation or <br /> neutralization might proceed,ABA is generally used as a screening tool to assess whether kinetic testing <br /> is needed to further characterize the potential for acid generation. <br /> The following criteria were used to interpret the ABA results: <br /> The potential for acid generation using the ratio of ANP to AGP has a tiered classification: <br /> • If the ratio is greater than 3:1, low risk for acid rock drainage (ARD); <br /> • If the ratio is between 3:1 and 1:1,there is a potential for ARD; or, <br /> • If the ratio is less than 1:1, it is likely acid generation will occur. <br /> The potential for acid generation using the Net Neutralizing Potential (NNP),which is calculated by <br /> subtracting AGP from ANP, has a tiered classification: <br /> • If the NNP is greater than+20 tons of calcium carbonate per 1,000 tons of rock(TCaCO3/KT),the <br /> material is considered non-acid generating; <br /> • If the NNP is between-20 and+20 TCaCO3/KT,the material is considered to be potentially acid <br /> generating; or, <br /> • If the NNP is less than-20 TCaCO3/KT,the material is considered to be acid generating. <br /> Paste pH is also an indicator of readily available acidity and can be used in conjunction with total pyritic <br /> sulfur content and ANP/AGP ratios as another assessment tool. If the paste pH is greater than 5.5 (s.u.) <br /> with a pyritic sulfur content less than 0.3%,there is a low risk for ARD to develop. <br /> According to the data presented in the table below, all samples except the Creede Formation Portal <br /> +1391-ft sample (F1391-051113) have ANP:AGP ratios in excess of 3:1, indicating low risk for acid <br /> generation. All of the samples fall into the low acid generation risk according to paste pH and <br /> corresponding pyritic sulfur content. The NNP classification places all of the samples in the potentially <br /> acid generating category. <br /> ABA Results <br /> ABATC- <br /> F1391- TC- ABATC- TBW 112213 TCSC TBWTC TBWTC TBWTC <br /> 051113 112213 112213 Comp 112213 SC <br /> Sample pH 5.73 11.06 10.05 8.19 10.35 10.09 10.70 10.40 9.23 <br /> Pyritic Sulfur 0.05 <0.01 <0.01 <0.01 0.02 <0.01 <0.01 0.03 0.03 <br /> AGP') 1.6 <0.3 <0.3 <0.3 0.6 <0.3 <0.3 0.9 0.9 <br /> ANP 2.0 13.7 15.8 11.5 11.6 3.7 5.8 10.5 6.3 <br /> NNP 0.4 13.7 15.8 11.5 11.0 3.7 5.8 9.6 5.4 <br /> ANP/AGP Ratio 1.25 45.67 52.67 38.33 19.33 12.33 19.33 11.67 7.00 <br /> 1) AGP based on Pyritic S-content (%S x 31.25). AGP,ANP and NNP in units of tons CaCO,equivalents per 1000 tons of solids. <br /> 4 <br />