High-temperature NMR (Proton magnetic resonance thermal analysis) was applied to study the fluidity of slightly-caking coals and coking coals. A pseudo component lumping analysis was made analyzing the free induction decays of these coals into three components, i.e., a rigid component, an intermediate compo-nent and a mobile component. The amount of the mobile component correlates the maximum fluidity (MF) obtained by the Gieseler plastmeter between MF=100-3000ddpm. It was found that the characterization using the amount of the mobile component is more useful than that using the maximum fluidity for several coals having small MF(MF<-20). It was also suggested that the intermediate component corresponds to a new component caused by the interaction of the mobile component with the rigid component in coal.
Research on the control of fluoride emissions from coal combustion is necessary to solve a serious fluoride pollution problem. In this work, CaCO3 and Ca (OH) 2 were used as defluorination agents to decrease fluoride emissions during coal combustion. When the molar equivalency of Ca to F2+S equaled 1.8, the resulting defluorination efficiency of Ca (OH) 2 was 50% and deSO2 efficiency was 63% at 900°C. Experimental results showed that defluorination efficiency increased with increasing fuel ratio of coals or decreasing temperature. White-coal, made by coating the surface of a coal briquette with a thin layer of Ca (OH) 2, was tested as a new solid fuel. The result shows that the white-coal emits less fluorides and SO2 in both volatile content combustion and char combustion.