Overview
ISO 19579:2006 specifies an alternative analytical method for determining the total sulfur content of solid mineral fuels (hard coal, brown coal and lignite) using high‑temperature combustion followed by infrared (IR) absorption measurement of combustion gases. The procedure is applicable to coal samples with an ash yield of less than 40% and uses commercially available instruments that integrate a furnace, gas‑purification train and a non‑dispersion IR detector with a microprocessor.
Key topics and technical requirements
- Principle: Sample combusted in oxygen at approx. 1 350 °C; combustion gases pass through glass wool and anhydrous magnesium perchlorate traps; sulfur dioxide (SO2) measured by IR absorption and quantified via instrument calibration.
- Sample preparation: Analysis sample ground to pass a 212 µm sieve; air‑dried to laboratory equilibrium and mixed before weighing.
- Test portion: Typical weighed mass 0.20–0.50 g (accuracy to 0.001 g) placed in ceramic combustion boats.
- Apparatus: Resistance furnace, ceramic combustion tube and boats, gas‑purification train (glass wool, Mg(ClO4)2), IR detector/microprocessor and a balance (1 mg resolution).
- Calibration: Use certified reference materials (CRMs) or reference coals/cokes traceable to an internationally recognized certifying organization. Calibrate across the expected sulfur range; verify calibration by analysing a CRM. Note: coals high in carbonates or certain low‑rank coals may need longer integration times.
- Quality control: Periodic calibration checks recommended (suggested after every five determinations). If calibration check fails, discard preceding results and recalibrate.
- Expression of results: Microprocessor calculates sulfur as mass percent; report mean of duplicate determinations to 0.01%.
- Precision: Repeatability r = 0.02 + 0.03x; reproducibility R = 0.02 + 0.09x (x = mean sulfur concentration).
Applications and users
ISO 19579 is intended for:
