Overview
ISO 1170:2020 - "Coal and coke - Calculation of analyses to different bases" provides standardized equations and procedures to convert analytical results for coal and coke between commonly used reporting bases. Typical bases covered include air-dried (ad), as-received (ar), dry (d), dry, ash‑free (daf) and dry, mineral‑matter‑free (dmmf). The standard also explains when and how to apply corrections (especially for mineral matter and water of hydration) before converting results.
Key topics and technical requirements
- Conversion formulas: Provides multiplication factors and formulae (see Table 1 of the standard) for converting mass fractions of constituents between bases.
- Bases and symbols: Uses suffixes like ad, ar, d, daf, dmmf and defines key symbols (C, H, N, S, O, Cl, w, MM, h, etc.).
- Corrections for mineral matter: Requires subtraction or correction of constituents associated with mineral matter (carbonate carbon, water of hydration, inorganic chlorine, pyritic and sulfate sulfur) when converting to a dry, mineral‑matter‑free basis.
- National correction factors: Allows use of national factors (e.g., Fh for water of hydration, FMM for mineral matter, FCl for inorganic chlorine) when direct determination is not available.
- Element-specific procedures:
- Carbon: subtract carbonate carbon before dmmf conversion.
- Hydrogen: deduct hydrogen in moisture and estimate mineral‑bound hydrogen (water of hydration) before dmmf conversion.
- Nitrogen: convert directly as it is not typically in mineral matter.
- Sulfur: subtract pyritic and sulfate sulfur to isolate organic sulfur for dmmf basis.
- Oxygen: usually calculated by difference; exercise caution since it aggregates errors.
- Chlorine: subtract inorganic chlorine before dmmf conversion; inorganic chlorine may be estimated with a factor.
- Volatile matter: apply corrections for mineral losses (CO2, hydration water, pyritic sulfur, chlorine) prior to dmmf conversion.
- Net calorific value: Not directly convertible by simple multiplication because it incorporates a moisture-related vaporization correction (see ISO 1928 for detailed calorific calculations).
- Coke analyses: Similar conversion approach for coke (ad, ar, d, daf), with relevant ISO methods referenced for moisture and ash determination.
Applications and who uses it
ISO 1170:2020 is essential for:
- Laboratories performing coal and coke proximate/ultimate analyses that need consistent reporting.
- Quality control and trade teams who compare results from different sampling/handling bases.
- Coal and coke producers, traders and power plants requiring standardized conversions for contracts, fuel specifications and combustion calculations.
- Researchers and regulatory bodies harmonizing datasets from different countries or historical reports.
Practical uses include converting test results for contract compliance, fuel blend formulation, emission estimates, and calorific assessments.
Related standards
ISO 1170:2020 references and complements other ISO methods for constituent determination:
Keywords: ISO 1170:2020, coal analysis, coke analysis, convert bases, dry mineral‑matter‑free, dry ash‑free, volatile matter, net calorific value, mineral matter corrections.
