Rosebud Coal Breaks

The lab prepared coal samples for Rosebud Coal identified as KDBH weekly Truck samples. The daily samples are subdivided into four splits. One of these daily split samples is combined with the other daily split samples (in this case, five days) to create a weekly composite. A split of the composite sample (here designated as “split A”) are forwarded by the lab to Coaltech for petrographic analysis. Split B is pulverized to 60M and analyzed by the lab. The fourth split (designated here a split D) is discarded.

The petrographic analysis on the KDBH weekly Truck composite split collected between 9/21 and 9/27 indicated the sample contained low volatile coal material, which the client believes was contaminated at the lab. The client requested corrective action.

The Coal Supervisor took remaining material from splits A and C from the week and had the lab analyze them for volatile matter. The results showed the 09/26/17 sample had a noticeably lower result compared with the other daily splits, This lower value (27.85%) was also lower compared with the result for the same day on “split B” (29.64)

The CS remade a weekly composite for the weekly composite using the remaining 8M material from the “C splits” but omitted the sample collected on 09/26/17. The composite of four days was sent
The original volatile result from Split B is in good agreement to the results from the other days, which may suggest the sample riffle contained same low volatile coal in a riffle pan (and not cleaned) before splitting. The precision for volatile analysis however, is not as good as other analysis such as ash, sulfur and Btus, making it unclear if this is where contamination took place. The short prox results are in good agreement to all other split results that a determination of contamination cannot be