Overview
ISO 2950:2025 - Brown coals and lignites - Classification by types on the basis of total moisture mass fraction and tar yield establishes a standardized system to classify brown coals and lignites by two measured properties: total moisture mass fraction (ash‑free basis) and tar yield (dry, ash‑free basis). The document defines classes and groups, prescribes a two‑digit coding system for types, and references the test methods required to determine the classification indices.
Key topics
- Classification principle: Types are defined by the combination of total moisture (ash‑free) and tar yield (dry, ash‑free).
- Class division (moisture): Six classes based on total moisture mass fraction on the ash‑free basis:
- Class 1: ≤ 20 %
- Class 2: > 20 to 30 %
- Class 3: > 30 to 40 %
- Class 4: > 40 to 50 %
- Class 5: > 50 to 60 %
- Class 6: > 60 to 70 %
- Group division (tar yield): Five groups based on tar yield on the dry, ash‑free basis:
- Group 0: ≤ 10 %
- Group 1: > 10 to 15 %
- Group 2: > 15 to 20 %
- Group 3: > 20 to 25 %
- Group 4: > 25 %
- Coding system: A two‑digit code identifies type - first digit = class (moisture), second digit = group (tar). Example: code 34 indicates class 3, group 4.
- Testing methods (normative references):
- ISO 5068-1 for total moisture (run‑of‑mine coal)
- ISO 647 for tar yield (low temperature distillation)
- ISO 1171 for ash determination
- ISO 5068-2 for moisture in analysis samples
Applications
ISO 2950:2025 is practical for organizations that need a consistent, internationally recognized way to describe brown coal and lignite types. Typical users include:
- Coal producers and mine operators for product characterization and marketing
- Analytical laboratories performing coal quality testing and reporting
- Power plants, fuel preparers and industrial users assessing feedstock properties
- Regulators and commodity traders requiring standardized coal type descriptors
- Researchers and technical consultants working on coal utilization and combustion studies
The standard supports comparability of coal quality data, specification of supply contracts, and informed decisions on handling, drying, and utilization based on moisture and tar characteristics.
Related standards
- ISO 5068-1 - Brown coals and lignites - Determination of total moisture (indirect gravimetric)
- ISO 5068-2 - Determination of moisture in the analysis sample
- ISO 647 - Determination of tar, water, gas and coke residue by low temperature distillation
- ISO 1171 - Coal and coke - Determination of ash
Keywords: ISO 2950:2025, brown coals, lignites, classification, total moisture mass fraction, tar yield, dry ash‑free, coal testing, ISO 5068, ISO 647, ISO 1171.
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