Overview
ISO 4691:2009 - "Iron ores - Determination of titanium - Diantipyrylmethane spectrophotometric method" specifies a validated laboratory procedure for measuring the mass fraction of titanium in iron ores. The method uses diantipyrylmethane as the colour-developing reagent and spectrophotometric measurement at approximately 385 nm. It is applicable to natural iron ores, iron ore concentrates and agglomerates (including sinter) in the range 0.02 % to 4.0 % Ti.
Key topics and technical requirements
- Scope and applicability: Measurement range 0.02–4.0 % Ti for ores, concentrates and sinter products.
- Analytical principle: Decomposition of a predried test portion (acid attack, alkali sintering or alkali fusion), reduction of iron with ascorbic acid, colour development with diantipyrylmethane, and absorbance measurement at ~385 nm.
- Sample preparation: Use laboratory samples of specified particle sizes (typically minus 100 µm; minus 160 µm for materials with significant combined water or oxidizable compounds) and predrying at 105 ± 2 °C as per ISO 7764.
- Reagents and standards: Lists required high-purity reagents (HF, HCl, HNO3, H2SO4, potassium disulfate, sodium peroxide, fusion mixes) and preparation of titanium standard solutions (0.1 mg Ti/ml and 20 mg Ti/l).
- Apparatus: Ordinary laboratory glassware complying with ISO 648 and ISO 1042, plus a spectrophotometer with 10 mm cells suitable for 385 nm.
- Quality control: Duplicate determinations, blank tests and certified reference material analyses run in parallel; procedures for calibration graphs, repeatability, between-laboratory precision and checks for trueness are defined.
- Safety note: The standard warns of hazardous reagents/operations and recommends appropriate health and safety practices.
Applications and who uses it
- Plants and laboratories performing chemical analysis of iron ore quality for beneficiation, grading and trade.
- Metallurgical laboratories monitoring titanium levels that affect smelting, steelmaking and impurity control.
- Quality assurance teams, mineral assay labs and research organizations needing standardized, reproducible Ti determinations.
- Useful for regulatory compliance, material specifications, trade certification and process control where accurate titanium quantification in ores/concentrates is required.
Related standards
- ISO 3082 (sampling and sample preparation for iron ores)
- ISO 7764 (preparation of predried test samples for chemical analysis)
- ISO 648 and ISO 1042 (laboratory glassware specifications)
Keywords: ISO 4691:2009, diantipyrylmethane, spectrophotometric method, titanium determination, iron ores, ore concentrates, sinter, analytical procedure, titanium in iron ores.