Overview
ISO 18894:2018 specifies laboratory methods for measuring the coke reactivity index (CRI) and coke strength after reaction (CSR) of lump coke (nominal top size > 20 mm). The standard defines the equipment, reagents and detailed procedures for exposing a representative coke sample to carbon dioxide at elevated temperature and for assessing post-reaction strength by tumbling. Its primary use is the testing of coke for ironmaking blast furnaces and related quality control in metallurgical operations.
Key topics and technical requirements
- Scope and sample size
- Test applies to lump-coke fraction 19.0 mm to 22.4 mm prepared and dried to <1% moisture.
- Minimum sample mass and division procedures are specified to ensure representativeness.
- Test principle
- Heat sample to 1 100 °C in nitrogen, then switch to CO2 for exactly 2 h; weight loss gives CRI (percentage weight loss).
- Reacted coke is tumbled (cylindrical tumbler) for 600 revolutions / 30 min; sieving (10.0 mm or 9.5 mm) gives CSR (percent retained).
- Equipment and instrumentation
- Electric furnace with a uniform temperature zone, single- or double-wall reaction vessel with perforated plates and a ceramic-ball gas preheater.
- Mass/variable-area flowmeters for N2 and CO2, thermocouple in gas-tight protection tube, tumbler with revolution counter, sieves (22.4, 19.0, 10.0/9.5, 0.5 mm), and a 0.1 g balance.
- Reagents and controls
- Dry nitrogen (>99.9%) and carbon dioxide (>99.5%) with low O2/CO2 impurities; gas flow and temperature control are critical to precision.
- Procedure and reporting
- At least two test runs are required. Results expressed as CRI (%) and CSR (%). The standard includes precision, repeatability and reproducibility guidance and required test-report content.
Applications and users
- Primary users: steelmakers, blast-furnace operators, coke producers, third‑party testing laboratories, and QC teams in metallurgical plants.
- Practical uses:
- Quality acceptance testing of blast-furnace coke.
- Raw-material assessment for ironmaking process optimization.
- Comparative evaluation of foundry coke or research studies (with caveats on precision).
- Benefits: standardized, reproducible assessment of coke reactivity and post-reaction mechanical strength to inform furnace performance and material selection.
Related standards
Normative and related references include:
Keywords: ISO 18894:2018, coke reactivity index, CRI, coke strength after reaction, CSR, blast furnace coke testing, coke testing standard, reaction vessel, tumbler test, sample preparation.
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