Table 3 Abundance of six forms of Se in sequential extraction fractions of the bulk sample (in μg/g) and fraction of each form of Se in three coals (in %)
| Â | Bituminous coal | Anthracite | Cokeite | |||
|---|---|---|---|---|---|---|
|  | Content (μg/g) | Fraction (%) | Content (μg/g) | Fraction (%) | Content (μg/g) | Fraction (%) |
Water-leachable | ND | 0.00 | 0.063 | 3.23 | 0.057 | 3.45 |
Ion-exchangeable | 0.128 | 4.66 | 0.138 | 7.14 | 0.186 | 11.3 |
Organic matter-bound | 1.08 | 39.1 | 0.219 | 11.3 | ND | 0.00 |
Carbonate-bound | 0.093 | 3.36 | 0.224 | 11.6 | 0.245 | 14.9 |
Sulfide-bound | 0.581 | 21.1 | 0.975 | 50.4 | 0.895 | 54.5 |
Silicate-bound | 0.875 | 31.8 | 0.316 | 16.4 | 0.259 | 15.8 |
Total | 2.76 | 100 | 1.93 | 100 | 1.64 | 100 |
Bulk coal (μg/g) | 4.00 | 2.43 | 2.00 | |||
Recovery (%) | 68.9 | 79.5 | 82.1 | |||