Program of Basic Research on the Preparation and Stability of Coal/Water Slurries. Quarterly Report.

摘要

For the Black Creek coal, aged samples are also more easily wetted than the freshly ground ones, though the change is not so extensive as for the Upper Freeport coal. Black Creek coal also appears to undergo surface oxidation of carbonaceous portions of the surface over time, independent of the grinding or aging atmosphere, as was the case to a much greater extent for the heavily oxidized Lower Kittanning sample. Slurries of freshly ground Black Creek coal have relatively high ionic strength due to the dissolution of soluble inorganic material from the coal surface, but aged samples yield a lower concentration of dissolved ions. The reason for this change is unknown. For the freshly ground samples, sedimentation rate and settled volume indicate extensive flocculation of the suspended coal as a result of the high ionic strength. The aged samples show much less sign of flocculation. The Pittsburgh Seam No. 8 ROM coal is the highest ash coal examined in this study. Its silicon and aluminum content are similar to that of Upper Freeport, but the Pittsburgh Seam No. 8 coal is also very high in iron. The cleaned coal contains about one-quarter as much aluminum, silicon, titanium and potassium as the ROM coal, and about one-tenth as much iron, calcium, magnesium, sodium and sulfur. The carbonaceous surface shows no sign of oxidation for either the ROM or cleaned coal. Electrophoretic mobility and viscosity data for freshly ground samples of the ROM and cleaned coals indicate the ROM coal appears to be much more extensively aggregated than the cleaned coal. The characterization of both the Pittsburgh Seam No. 8 samples is not yet complete, but the evidence to date suggests that the ROM sample is similar to the Upper Freeport coal, while the cleaned coal provides an example of the effects of beneficiation on a very high ash coal. 45 figs., 41 tabs. (ERA citation 11:031364)