| Popis: |
The −0.5 inch (−1.27 cm) and −28 mesh (−600 μm) fractions of the run-of-mine coals from seven western Kentucky preparation plants were crushed to 90 percent passing 200 mesh (75 μm) and processed through high-gradient magnetic separation (HGMS). Petrographic analysis of the clean and refuse fractions indicated that the refuse contained nearly the same amount of vitrinite as the associated clean coal. This contrasts with the findings for other fine coals from the same plants where fine refuse had consistently less vitrinite and more fusinite and semifusinite than fine clean coals. Pyrite remaining in HGMS clean coals was significantly finer than pyrite in the refuse. Most of the pyrite in the clean was less than 5 μm in diameter, and, in all but one case, greater than 98 percent of the “clean” pyrite was less than 10 μm. |
