ASTM D2415 Standard Test Method for Ash in Coal Tar and Pitch
9. Procedure
9.1 Ignite a clean dish or crucible for 1 h in the muffle furnace at 900 °C +/- 10 °C. Cool slowly to about 100 °C, then place the dish or crucible in a desiccator. When at room temperature, weigh to the nearest 0.1 mg.
9.2 Transfer a 10 g portion of the representative, dehydrated sample to the tared dish or crucible and weigh to the nearest 0.1 mg. Place the container and the sample in the cold muffle furnace and gradually heat to redness at a rate that avoids mechanical loss from boil-over or spattering, due to too rapid an expulsion of volatile matter. Instead of the muffle furnace, a hot plate or gas flame may be used to remove volatiles, as long as the same precautions against mechanical loss are taken. After the volatile matter has been driven off and a semi-coke remains, complete the ignition in the muffle furnace at 900 °C +/- 10 °C. When all carbon appears to have burned off, cool the dish or crucible to about 100 °C before placing it in a desiccator. When at room temperature weigh to the nearest 0.1 mg. Repeat the ignition at 900 °C +/- 10 °C for 30 min intervals until constant weight is obtained.
10. Calculation
10.1 Calculate the ash content of the sample as follows:
Ash, % = 100A/B
where:
A = weight of ash, and
B = weight of sample.
