Overview
ISO 7215:2015 - Iron ores for blast furnace feedstocks - Determination of the reducibility by the final degree of reduction index - specifies a laboratory test method to provide a relative measure of how readily oxygen can be removed from iron ores under conditions resembling the reduction zone of a blast furnace. The method yields the final degree of reduction (R180) after isothermal reduction at 900 °C for 180 minutes and is applicable to lump ore, sinters, and hot‑bonded pellets. Results are intended for quality control, contract specification and research.
Key topics and technical requirements
- Test principle: Isothermal fixed‑bed reduction at 900 °C (±10 °C) using a CO/N2 reducing gas; final degree of reduction (R180) is calculated from oxygen mass loss after 180 min.
- Reducing gas: Composition CO 30.0% ±1.0% and N2 70.0% ±1.0%; strict impurity limits (e.g., O2 ≤ 0.1%); flow rate 15 L/min ± 0.5 L/min.
- Heating/cooling gas: Nitrogen with impurity limits and flow control (e.g., 5 L/min while heating/cooling; 15 L/min for equilibration).
- Sample preparation: Follow ISO 3082 sampling; oven‑dry to constant mass at 105 °C ±5 °C; sized material ranges - pellets: −12.5/+10.0 mm; sinters/lumps: −20.0/+18.0 mm.
- Test portions: Minimum five portions ≈ 500 g each (four for testing, one for chemical analysis). Weighing accuracy and tare procedures required.
- Apparatus: Reduction tube (internal diameter ~75 mm ±1 mm), furnace with balance (mass resolution 0.5 g), gas‑supply system and thermocouple positioned at bed centre.
- Chemical analysis: Determine Fe2+ (ISO 9035) and total Fe (ISO 2597‑1 / ISO 2597‑2) for calculation inputs.
- Safety: CO is toxic - tests must be performed with proper ventilation and safety controls.
Applications and who uses it
- Steel plants and blast furnaces - evaluate feedstock reducibility for blast furnace performance modeling and blend optimization.
- Quality control laboratories - monitor production consistency of pellets, sinters and lump ores.
- Trading and contracts - provide a standardized, comparable metric (R180) for specification and contractual acceptance.
- Research & development - study ore behaviour, validate process simulations, and compare alternative raw materials.
Related standards
Keywords: ISO 7215:2015, reducibility, final degree of reduction, R180, iron ores, blast furnace feedstock, reducing gas, pellets, sinters, lump ore, quality control.