Pelletization of fine coals

The present research project attempts to provide a basis to determine the pelletizability of fine coals, to ascertain the role of additives and binders and to establish a basis for binder selection. Currently, there are no established techniques for determining the quality of coal pellets. Our research is intended to develop a series of tests on coal pellets to measure their storage characteristics, transportability, ease of gasification and rate of combustion. Information developed from this research should be valuable for making knowledgeable decisions for on-time plant design, occasional binder selection and frequent process control during the pelletization of coal fines. During the last quarter, we continued the batch pelletization studies on Upper Freeport coal. The results as presented in that last quarterly report (April 1991) indicated that the surface conditions on the coal particle influenced the pelletizing growth rates. For example, a fresh (run of mine) sample of coal will display different pelletizing growth kinetics than a weathered sample of the same coal. Since coal is a heterogeneous material, the oxidized product of coal is equally variable. We found it to be logistically difficult to consistently produce large quantities of artificially oxidized coal for experimental purposes and as such we have used a naturally weathered coal. We have plans to oxidize coals under controlled oxidizing conditions and be able to establish their pelletizing behavior. The next phase of experiments were directed to study the effect of surface modification, introduced during the coal cleaning steps, on pelletizing kinetics. Accordingly, we initiated studies with two additives commonly used during the flotation of coal: dextrin (coal depressant) and dodecane (coal collector)