Overview - ISO 5072:2021 for brown coals and lignites
ISO 5072:2021 specifies laboratory methods to determine the true relative density (TRD) and the apparent relative density of brown coals and lignites. The standard describes sample preparation, required reagents and apparatus, step‑by‑step procedures and calculation formulas for both densities. It is applicable to general analysis test samples prepared to a nominal top size of 212 µm and references related moisture and sampling standards.
Key topics and technical requirements
- Two distinct methods
- True relative density (TRD) - Pycnometric water‑displacement method using a wetting agent to ensure dispersion; degassing under vacuum; thermally controlled water bath at 25 °C ± 0.1 °C.
- Apparent relative density - Determined by weighing the sample suspended in water, allowing drainage, then reweighing in air to assess the apparent volume.
- Essential apparatus and reagents
- TRD: 50 ml pycnometers with capillary‑bored stoppers, analytical balance (0.1 mg), vacuum desiccator and pump, glass syringe, wetting agent (e.g., 5% SDS), thermostatic water bath, thermometer.
- Apparent density: beam balance (sensitive to 10 mg), top‑pan balance, vacuum pump (≈250 Pa), evaporating dishes, paper towels.
- Sampling and sample handling
- Use general analysis test samples prepared (to 212 µm) per ISO 13909‑4 or ISO 18283.
- Moisture equilibrium and concurrent duplicate moisture determinations (ISO 5068‑2) are required for correct expression of results.
- Calculations and reporting
- ISO 5072 provides the formulae for TRD calculations and expression of results.
- Precision for TRD: repeatability r = 0.02% and reproducibility R = 0.04%.
- Test report must identify the sample, reference ISO 5072:2021, date of determination and the results with method of expression.
Applications - who uses ISO 5072:2021
- Coal testing laboratories performing routine characterization of brown coal and lignite samples.
- Power plants, fuel suppliers and quality control groups verifying fuel quality parameters that affect combustion, handling and processing.
- Research institutes and consultants studying physical properties, beneficiation and processing behaviour (e.g., bulk density, combustion modelling).
- Regulatory and procurement teams requiring standardized density data for specifications and trade.
Related standards
Keywords: ISO 5072:2021, brown coals, lignites, true relative density, apparent relative density, pycnometer, water displacement, coal testing, sample preparation, ISO 5068.