Ash loss and the 'seeded-tracer' technique for the determination of mass balance in rapid heating coal pyrolysis experiments

Pulverized-coal pyrolysis experiments have been conducted in an inert gas, Ar, under conditions of high heating rate (10 5 –10 6 K/s), and high temperature (2000–2800 K). The dry-ash-free (daf) mass loss was calculated on the basis of a seeded-tracer, tungsten carbide powder, and on the basis of a natural tracer, titanium. The former method gave consistently higher daf mass loss. The data indicate that under these test conditions mineral elements in the coal, including some major and minor species, leave the parent coal and therefore cannot serve as a tracer for the determination of mass loss as is often done conventionally. The loss of some mineral elements is correlated with the daf mass loss. Criteria for the selection of a seeded tracer are discussed.