2010-12-17_REVISION - C1981019 (130)

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In addition, all but 4 of the re- analyzed ASG values were higher than the original values. This increase is probably a result of moisture loss in the original samples. It should also be noted that the ASG data originally provided by SGS was rounded to the nearest one - hundredth of an ASG point. Therefore, using strict rounding protocol ASG values reported at 1.33 could have more calculated values ranging from 1.325 to 1.334. Furthermore, it is likely that lower ash points trended to the 1.325 values and higher ash values trended to the 1.334 values. However, the precision of the test does not warrant reporting of ASG values beyond the nearest one - hundredth. The re- analyzed ASG values shown on Figure 1 have not been rounded to the nearest one - hundredth. Therefore, these data show little stratification of the data on the scatter - graph. Additionally, the Australian Standard AS1038 for Relative Density uses 0.08 as a valid repeatability value. If this same limit is applied to the original ASG values at 1.33, then the range of acceptable repeated values would be 1.29 to 1.37. When applied to the retested ASG values 8 data points reside outside the acceptable range and 40 reside within the acceptable range. The conclusions inferred from the re- analyzed ASG values are: The ASG test does not provide good repeatability. Although most retested values did reside within repeatability limits. • ASG is apparently affected by moisture loss in coal samples. • The decimal reporting precision of the test stratifies the data when presented on scatter - graphs. Proposed ASG Sampling Program Due to the inconclusive results of the re- analyzed ASG values, it is proposed that a more detailed sampling and analytical testing be performed by Colowyo. The additional testing will hopefully lead to more consistent ASG values and increase general knowledge in the density of Colowyo coal.