Page 182 - Advances In Productive, Safe, and Responsible Coal Mining

162 Advances in Productive, Safe, and Responsible Coal Mining

When the Clean Air Mercury Rule (CAMR) passed, allowances were expected to
trade for approximately $2000 per ounce ($32,000 per pound) [13]. This value was
used to determine cost impacts due to increased levels of trace elements from mining
OSD. Finally, in assessing quality impacts, average transportation costs of $7 per
clean ton and a selling price of $1.50 per million British thermal units (MMBTU) were
used for Illinois coal based upon one of the previously referenced studies [11].

9.2.7.4 Waste disposal costs
Since most of the mined OSD material is rejected during processing, disposal must be
considered in assessing cost impacts. In the United States, coal mine waste material is
typically disposed of in “gob” piles and slurry impoundments, although serious con-
sideration is being given to backfilling, which is more common practice internation-
ally. Previously developed disposal cost estimates for coarse and fine refuse [14] are
used in this case. They consider only operational costs of waste disposal and ignore
indirect disposal costs associated with land acquisition, permitting, and reclamation,
all of which have risen dramatically since the turn of the century [15].

9.3 Modeling results

9.3.1 Product quality impacts of OSD

To show the depth of analysis on product quality developed in Patwardhan’s study,
results obtained for one channel sample collected at one mine are presented. Then,
summary results for all samples are provided.

9.3.1.1 Detail of quality analysis for mine 1 #2 sample
As described earlier, the #2 channel sample collected at mine 1 included separate roof
rock, coal seam, and floor clay fractions. Measured thicknesses of these fractions were
10.2, 58.9, and 5.0in., respectively. Specific gravities were 2.1, 1.4, and 2.6, respec-
tively. Based on these data, percentages of each fraction in the ROM coal were cal-
culated at 18.0%, 71.2%, and 10.8%, respectively. By simulating a density cut point of
1.9, product quantity and quality were estimated as shown in Table 9.1.
The model predicts that mining and processing (at a 1.9 specific gravity cut point)
the entire 74.1 in channel profile results in a yield of 66.72% achieved at ash, sulfur,
and mercury contents of 7.69%, 0.87%, and 0.092ppm, respectively. If only the coal
seam material is mined, the model predicts a yield of 66.0% at ash, sulfur, and mer-
cury contents of 7.14%, 0.87%, and 0.087ppm, respectively. Thus, extracting
15.2in. of OSD gains just 0.72% in mass yield but increases clean coal ash content
by 7.6%, clean coal sulfur content by 0.95%, and clean coal mercury content by
6.0%. Contents of trace elements As, Pb, and Se also increase by 7.5%, 1.5%,
and 64.3%, respectively.