Overview
ISO 4298:2022 specifies a potentiometric titration method for the determination of manganese content in manganese ores and concentrates with a manganese mass fraction ≥ 15 %. The procedure combines acid decomposition, separation of insoluble residues (with ignition and fusion where needed), and potentiometric titration of Mn(II) with potassium permanganate in a neutral sodium pyrophosphate medium. The standard is intended to deliver traceable, reproducible manganese assays for quality control, trade and laboratory reporting.
Key topics and technical requirements
- Scope: Applicable to manganese ores and concentrates containing ≥ 15 % Mn.
- Analytical principle: Oxidation of Mn(II) by permanganate in pyrophosphate solution with potentiometric endpoint detection (stoichiometry considered).
- Sample size: Test portion updated to 0.50 g (reduced from earlier editions).
- Sample preparation:
- Acid decomposition using hydrochloric, nitric, perchloric and hydrofluoric acids.
- Separation of residue; ignition and fusion with sodium carbonate; leaching and combination with main filtrate.
- Titration conditions:
- Aliquot mixed with saturated sodium pyrophosphate; pH adjusted to 7.0.
- Potentiometric titration with standard potassium permanganate solution (c ≈ 0.1 mol/L) until maximum voltage deflection.
- Standardization:
- Two standardization routes described: using a manganese standard reference solution (electrolytic Mn) or by gravimetric preparation from purified KMnO4.
- Blank determinations required.
- Results and reporting:
- Calculation formulas account for hygroscopic moisture (ISO 310 referenced).
- Clauses on precision, between-laboratories testing, trueness checks, and final-result calculation.
- Test report requirements and annexes: Annex A (interlaboratory information) and Annex B (acceptance flow chart).
- Reagents and apparatus: Lists required acids, sodium pyrophosphate, reagents (high-purity KMnO4), potentiometric titration apparatus and pH electrode; water quality per ISO 3696 and laboratory glassware standards.
Applications and users
ISO 4298:2022 is practical for:
- Analytical laboratories performing manganese assays for ores and concentrates.
- Mining companies and metallurgical plants conducting incoming material QC and product certification.
- Ferroalloy producers, commodity traders and inspection bodies that require standardized, comparable manganese content results.
- Laboratories participating in interlaboratory studies or seeking conformity with international sampling and testing workflows.
Related standards (normative references)
- ISO 310 - Hygroscopic moisture in analytical samples (gravimetric)
- ISO 4296-1 / -2 - Sampling and sample preparation for manganese ores
- ISO 3696 - Water for analytical laboratory use
- ISO 1042 / ISO 648 - Laboratory glassware specifications
Keywords: ISO 4298:2022, manganese ores, manganese concentrates, potentiometric method, permanganate titration, sodium pyrophosphate, manganese determination, laboratory standard, manganese assay.