THE EFFECT OF SELECTED ADDITIVES AND TREATMENTS ON GIESELER FLUIDITY IN COALS

The modification of Gieseler fluidity development in coals by various pretreatments is examined and clarified, These pretreatments include the addition of solvent extracts, preheating and quenching, addition of radical stabilizers and blending. The effect of each treatment is found to be dependent on the degree to which it satisfies the requirements of the hydrogen donor theory of fluidity development. This includes changes in behaviour which would otherwise be difficult to explain, such as the very different effect preheating has on the fluid properties of fresh and oxidized samples of the same coal. From a chemical viewpoint the components in blends are found to behave predictably. That this does not always translate into predictable fluidity development can be attributed to chemical differences between the components and the consequences these have for the fluidity development process as described by the hydrogen donor theory.