Overview
ISO 556:2020 specifies a standardized laboratory method for the determination of the mechanical strength of coke with particle sizes greater than 20 mm. The document defines two complementary tests - Micum (100 drum revolutions) and Irsid (500 revolutions) - that quantify coke breakage under controlled mechanical stress in a rotating drum. Results are reported as size distributions after sieving and used to calculate Micum and Irsid indices that indicate coke cohesion and resistance to degradation.
Key topics and technical requirements
- Test scope: Coke samples with bottom sizes >20 mm (40 mm or 60 mm may be used if stated in the report).
- Sample preparation: Gross sample per ISO 18283 or ISO 13909-6; size analysis per ISO 728. Test portion: 50 ± 0.5 kg for full Micum/Irsid, 25 ± 0.25 kg for half tests.
- Moisture: Sample moisture must be < 3 %; oven-dry if higher.
- Apparatus:
- Cylindrical steel drum with internal diameter and length 1 000 ± 5 mm for full tests (half-drum 500 ± 5 mm length), wall thickness ~6 mm, four internal lifters.
- Drum rotation: 25 ± 1 r/min with revolution counter.
- Mandatory sieves: 40 mm, 20 mm, 10 mm (additional sieve sizes optional; reference ISO 3310-2).
- Weighing, trays and containers sized for 50 kg (or 25 kg) portions.
- Procedure: Charge test portion, run specified revolutions (Micum 100, Irsid 500), allow dust to settle, empty and sieve. Report results as percent fractions (e.g., >40 mm, >20 mm, <10 mm) and compute Micum/Irsid indices.
- Equipment maintenance: Measure drum wall and lifter wear every 500 tests; replace if below specified dimensions.
- Reporting: Must state test type (Micum/Irsid/half), whether single or duplicate determinations were made, starting bottom size, and test results. Precision and repeatability guidance provided in Clause 9.
Applications and users
- Primary users: Coke producers, metallurgical plants (blast furnace and foundry coke), quality-control laboratories and research institutions.
- Practical uses:
- Quality control of coke strength for smelting and metallurgical processes.
- Comparing coke batches or carbonization conditions.
- Ensuring compliance with contractual specifications and process feedstock requirements.
- Supporting product development and process optimization in coke manufacture.
Related standards
- ISO 728 - Size analysis by sieving (coke)
- ISO 18283 - Manual sampling (hard coal and coke)
- ISO 13909-6 - Mechanical sampling - Coke - Preparation of test samples
- ISO 3310-2 - Test sieves - Perforated plate
Keywords: ISO 556:2020, coke mechanical strength, Micum test, Irsid test, coke testing, coke (>20 mm), coke cohesion, coke quality control.