Overview - ISO 602:2015: Coal - Determination of mineral matter
ISO 602:2015 specifies a standardized laboratory method for determining the amount of mineral matter in all types of coal, including brown coals and lignites. The method uses controlled partial demineralization with hydrochloric and hydrofluoric acids, measurement of mass loss and residual ash, and correction for pyrite (iron) and acid uptake to report mineral matter as a percentage on a dry basis.
Key topics and technical requirements
- Principle: Partial demineralization with HCl and HF so that coal substance remains unaffected; measure mass loss; ash the undissolved residue; determine iron (to account for pyrites) and HCl absorbed by coal.
- Reagents: Analytical-grade hydrochloric acid (concentrated and 5 mol/L solution) and hydrofluoric acid (HF).
Warning: HF is highly toxic and corrosive - strict safety controls required.
- Apparatus: Acid-resistant equipment (PVC recommended), 200 ml beaker with cover, thermometer pocket, stirrer, quantitative filter paper (≈1 µm) with sintered alumina filter plate, suction flask, balance (0.1 mg accuracy).
- Sample preparation: Analysis sample ground to pass 200 µm sieve; mix thoroughly; moisture equilibrium per ISO 11722 or dry at 105–110 °C if required.
- Procedure highlights: Typical test portion ≈6 g; HCl extraction, then HF extraction, followed by additional HCl and extensive hot-water washing. Controlled heating at 55–60 °C (e.g., 45 min), settling and vacuum drying (≈50 °C, 3.5 kPa, ~1.5 h) before weighing.
- Calculations & reporting: Mineral matter percentage is calculated from masses before and after extraction, mass of pyrite (from Fe in ash), mass of HCl absorbed, and residual ash (with a 1.1 factor to allow for hydration of Al/Si compounds). Results reported on a dry basis, preferably mean of two determinations, to 0.1% resolution.
- Precision: Repeatability (same lab, same operator) maximum acceptable difference ≈ 0.4% absolute.
Practical applications and users
ISO 602:2015 is used by:
- Coal testing laboratories and quality control teams
- Power plants and utilities for fuel characterization and combustion planning
- Coal producers, traders and metallurgical coke manufacturers for product specification
- Environmental and regulatory agencies assessing mineral-related emissions and ash behavior
- Research institutions studying coal petrology, beneficiation or combustion chemistry
Benefits include consistent measurement of mineral matter, improved comparability of coal quality data, and support for decisions on handling, blending, and emissions controls.
Related standards
- ISO 11722 - moisture determination in analysis sample
- ISO 1171 - determination of ash in solid mineral fuels
- ISO 157 - determination of forms of sulfur (for Fe/pyrite analysis)
- ISO 587 - determination of chlorine
- ISO 1170 - calculation of analyses to different bases
Keywords: ISO 602:2015, mineral matter in coal, coal analysis, hydrofluoric acid, hydrochloric acid, coal ash, mineral matter factor, coal quality testing.
