The effects of coal particle size and the percentage of coal present in the slurry on the leaching of organic compounds from wyodak coal

The effects of coal particle size and the percentage of coal present in the slurry on the leaching of organic compounds from Wyodak coal was determined using analysis of variance.

The initial nonvolatile (NVTOC) ranged from 40 to 387 ppm and the extraction NVTOC ranged from 26 to 362 ppm. Coal particle size had no affect on these nonvolatile TOC concentrations while the percentage of coal present in the slurry did. As the percentage of coal present in the slurry increased, the NVTOC levels also increased.

Three peaks representing organic compounds extracted from the coal leachate were analyzed and separated using high performance liquid chromatography. Peaks 1, 2, and 3 eluted from a C18 HPLC column at 1.5, 3.5, and 15 minutes, respectively. The normalized peak responses were; Peak 1: 0.08 to 12.0, Peak 2: 0.0 to 12.0, and Peak 3: 0.0 to 1.13. ANOVA results indicate that coal particle size significantly affected the normalized responses of Peaks 1 and 3, but this affect was not clear.

The percentage of coal present in the slurry was found to affect the normalized responses of all three peaks and the Total Peak response. Generally as the percentage of coal present in the slurry increased, the peak responses also increased.

Molecular weight analysis indicates that most of the organic com-pounds present in the coal leachate are of relatively low molecular weight (≈100).

Based on HPLC analyses, molecular weight analyses, and the structure of coal itself, most of the organic compounds present in the leachate are probably heteroatom (oxygen, nitrogen, and sulfur) containing aromatic compounds of relatively low molecular weight (≈100).