Thermodynamic studies are of interest for any chemically reacting system. Thermodynamics constitute the limiting cases for kinetically reacting systems. In many systems, as a result of the exponential nature of most chemical reactions (reaction rate = k Ae/sub -..delta..H/RT/), reactions of interest occur over a fairly narrow temperature region. At lower temperatures, reaction rates are negligible, while at higher temperatures the reaction can be so rapid as to be controlled either by thermodynamics or mass transfer. Thus, thermodynamic equilibrium at a characteristic temperature can often be a close approximation to a kinetic system. Previous work by Stephens in the coal-water-oxygen thermodynamic system is extended. Results with 20 percent combustion and amorphous carbon are shown to be a good approximation to kinetic data. Experimental Lurgi coal gasification data are closely approximated by a calculated thermodynamic temperature of 1060 K. This temperature is used to show that for underground coal gasification with a constant oxygen/coal ratio, optimum steam/oxygen ratios should be as low as possible. Probably the steam/oxygen ratio should exceed 3.6 to avoid slagging of the ash. At this ratio, about twice as much methane can be obtained in comparison to the Lurgi ratio of 7.7. (auth)

A preliminary set of experiments was conducted in order to determine the sorptive characteristics of rock with respect to ionic species under conditions of dynamic flow of an aqueous solution through a rock core. The results of the dynamic experiments have been compared to the results of static or batch experiments which were conducted under corresponding physical and chemical conditions. It was found that, gram for gram, sorption of the ion of interest was always greater in the dynamic experiments. These results are contrary to early predictions and indicate that the effect of rock surface area on adsorption was overshadowed by another parameter. It has been suggested as a working hypothesis that the competitive effect of ions that were dissolved and/or leached from the rock in batch experiments has resulted in reduced sorption of the ion of interest. If the hypothesis is confirmed by further experimental work, a ramification of the study is that calculations concerning transport of radioactivity in groundwater which utilize input parameters derived from static tests will tend to be conservative with respect to what occurs in nature. (auth)