ISO 4689-2:2017 PDF

Overview

ISO 4689-2:2017 specifies a validated combustion/titration method for the determination of sulfur content in iron ores. The procedure applies to natural iron ores, iron ore concentrates and agglomerates (including sinter products) with sulfur contents from 0.002 % to 0.25 % (mass fraction). Results are not affected by fluoride. The standard defines sample preparation, reagents, apparatus, test procedure, calculation, precision and reporting requirements for reliable sulfur analysis.

Key topics and technical requirements

• Principle: Sample is mixed with tungsten(VI) oxide (WO3) and combusted at 1 200 °C ± 25 °C in a resistance furnace using nitrogen as carrier gas. Evolved SO2 is absorbed in dilute hydrochloric acid containing starch and potassium iodide (KI) and titrated continuously with a standard potassium iodate (KIO3) solution.
• Applicable range: 0.002 % – 0.25 % S (mass fraction).
• Test portion mass:
  • 0.002–0.100 % S → 1.0 g test portion
  • 0.100–0.25 % S → 0.5 g test portion
• Reagents & solutions: analytical-grade reagents; KIO3 standard (0.001042 mol/L) where 1 mL = 0.10 mg S. Use tungsten oxide, tin(II) chloride (if chlorides present), Mg(ClO4)2 and NaOH-coated silica in drying train.
• Apparatus essentials: resistance furnace, refractory combustion tube/boat or cartridge, drying tower, flowmeter, multi-hole bubbler and burette (or micro-syringe/piston burette for very low S