ISO 1952:2025

Overview

ISO 1952:2025 - Coal - Determination of extractable metals in dilute hydrochloric acid describes a standardized laboratory method to extract and quantify sodium, potassium, calcium, iron and magnesium that are extractable from coal using dilute hydrochloric acid. The method is intended for coal quality assessment and research into coal-utilization problems (e.g., fouling and slagging). Extraction is followed by instrumental determination primarily by atomic absorption spectrometry (AAS), with ICP‑OES permitted when suitably validated.

Key topics and technical requirements

• Scope: Extraction from coal by dilute HCl and measurement of extractable Na, K, Ca, Fe, Mg.
• Principle: Wet the coal with ethanol, extract with hot dilute HCl, filter, and measure element concentrations in the filtrate by AAS (or validated ICP‑OES).
• Representative sample & test portion: General test sample prepared per ISO 13909‑4 or ISO 18283; typical test portion ~1.5 g (determined to nearest 2 mg).
• Extraction procedure:
  • Add 4 ml ethanol to wet the sample, add 50 ml water and 8 ml dilute HCl (1:1 with water).
  • Heat at just below boiling for 15 min, then continue 45 min (maintain ~50 ml volume).
  • Cool, decant and filter into a 250 ml volumetric flask, rinse with hot HCl solution, add 10 ml lanthanum solution, make to volume.
• Reagents & calibration:
  • Use high‑purity water (ISO 3696), analytical‑grade reagents; lanthanum solution used as ionization suppressant for Ca (other suppressants like cesium may be used).
  • Calibration solutions typically prepared in the 1–5 mg/l range with lanthanum and dilute HCl; include a reagent blank.
• Instrumentation & settings:
  • AAS recommended wavelengths (air‑C2H2 fuel): K 766.5 nm, Na 589.6 nm, Mg 285.2 nm, Ca 422.7 nm, Fe 372.2 / 248.3 nm.
  • Aspirate water between readings; periodically recalibrate.
• Quality & reporting: Clauses cover precision (repeatability/reproducibility), test report contents and required apparatus and glassware.

Applications and users

ISO 1952:2025 is used by:

• Coal testing laboratories and quality control units
• Power utilities and boiler operators evaluating fouling/slagging risk
• Coal producers and traders assessing product quality
• Environmental and combustion researchers monitoring ash chemistry
• Instrumentation labs implementing standardized AAS/ICP‑OES methods

Practical benefits include consistent, comparable data on the acid‑extractable fraction of alkali and alkaline‑earth metals-information more closely linked to fouling/slagging behavior than total metal content.

Related standards

• ISO 1042 - Laboratory glassware (volumetric flasks)
• ISO 3696 - Water for analytical laboratory use
• ISO 5068‑2, ISO 11722 - Moisture determination methods
• ISO 13909‑4, ISO 18283 - Sampling and preparation of coal samples

Keywords: ISO 1952:2025, coal analysis, extractable metals, dilute hydrochloric acid, atomic absorption spectrometry, ICP‑OES, sodium, potassium, calcium, iron, magnesium.