ISO 9517:2007

Overview

ISO 9517:2007 - "Iron ores - Determination of water‑soluble chloride - Ion‑selective electrode method" specifies a potentiometric procedure to determine the mass fraction of water‑soluble chloride in iron ores, concentrates and agglomerates (including sinter). The method is applicable to the range 0.007 % to 0.1 % water‑soluble chloride and defines the sampling, sample preparation, reagents, apparatus and calculation rules required for reliable chloride determination.

Key topics and technical requirements

• Analytical principle: Leaching of a predried test portion in water with potassium sulfate, filtration and potentiometric measurement with a chloride ion‑selective electrode (ISE) and a double‑junction reference electrode after addition of phosphate buffer, potassium persulfate (oxidant) and an ionic‑strength adjuster (sodium nitrate).
• Measurement range: Valid for 0.007 % to 0.1 % water‑soluble chloride in natural iron ores and derived products.
• Calibration: Preparation of calibration solutions (examples: 2, 3, 5, 10, 25, 50 µg Cl−/ml) using defined standard solutions; low‑level calibrations (2–10 µg/ml) should be prepared on the day of use.
• Apparatus and consumables: Chloride ISE and separate double‑junction reference electrode (combined electrodes not suitable), high‑impedance meter with 0.1 mV sensitivity, microfilters (cellulose membrane, <1 µm pore size), PTFE‑covered stirring bars and magnetic stirrer/hotplate.
• Sample preparation: Use a laboratory sample milled to minus 100 µm (or <160 µm for ores with combined water/oxidizable compounds) and prepare predried test samples at 105 °C ± 2 °C.
• Quality control: Perform analyses at least in duplicate independently; include a certified reference material in each run; follow check tests for electrode system and contamination.
• Practical notes: Some chloride electrodes are light‑sensitive; maintain outer chamber flow of the reference electrode; clean stirring bars to remove chloride contamination.

Applications and users

ISO 9517:2007 is used by:

• Laboratory analysts in mining and metallurgical QA/QC programs for iron ore quality control.
• Iron ore producers, sinter plants and agglomeration facilities monitoring soluble chloride that can affect downstream processes (corrosion, sinter quality).
• Contract testing labs and instrument manufacturers validating chloride ISE performance for low‑level chloride assays.
• Regulatory and standards bodies requiring traceable chloride determinations in ore characterization.

Related standards

• ISO 3082 - Sampling and sample preparation procedures for iron ores
• ISO 7764 - Preparation of predried test samples for chemical analysis
• ISO 648, ISO 1042 - Specifications for laboratory glassware (pipettes and volumetric flasks)

Keywords: ISO 9517:2007, ion‑selective electrode, water‑soluble chloride, chloride determination, iron ores, potentiometric method, chloride ISE, ore quality control.