Overview
ISO 5890:1981 specifies a gravimetric method for the determination of silicon content in manganese ores and concentrates. The procedure is intended for samples with silicon (Si) content greater than 0.5% (m/m) and fluorine not exceeding 0.1% (m/m). The standard defines the analytical principle, required reagents and apparatus, the stepwise procedure and how results are expressed. ISO 5890 is to be read in conjunction with ISO 4297 (general instructions for chemical analysis of manganese ores).
Key topics and technical requirements
- Analytical principle: Acid decomposition (HCl, HNO3, HClO4), filtration of residue, ignition and fusion of residue with sodium carbonate, leaching and recombining solutions, precipitation and isolation of silica; volatilization of silica with HF/H2SO4 and gravimetric calculation by mass difference.
- Scope limits: Applicable when Si > 0.5% (m/m) and F ≤ 0.1% (m/m).
- Reagents (examples cited):
- Hydrofluoric acid (density ≈ 1.14 g/ml)
- Perchloric acid (density ≈ 1.51 g/ml)
- Nitric acid (density ≈ 1.40 g/ml)
- Hydrochloric and sulphuric acids, sodium carbonate, hydrogen peroxide
- Apparatus:
- Muffle furnace controllable between 1 000–1 100 °C (ash/incineration steps)
- Platinum crucibles for ignition, fusion and weighing
- Standard laboratory glassware for evaporation, filtration and heating
- Procedure highlights:
- Selection of test portion mass according to expected Si content
- Controlled acid digestion, repeated washings, ignition and fusion of residues
- Separation and purification of silica precipitate, volatilization with HF + H2SO4
- Gravimetric determination and calculation of Si percentage (option to report as SiO2 using factor 2.139)
- Quality checks: Blank test required; permissible tolerances for parallel determinations are specified by Si range (e.g., for 0.5–1.0% Si, two-parallel tolerance 0.06% m/m).
Applications and who uses it
- Analytical and quality control laboratories in mining, metallurgy and mineral processing for assaying manganese ore and concentrate shipments.
- Process control teams monitoring feedstock composition for smelting or alloy production.
- Contract laboratories providing certified analyses for commercial trading and regulatory compliance.
- Standards bodies and method validators comparing gravimetric results with instrumental techniques.
Related standards
- ISO 4297 - Manganese ores and concentrates: Methods of chemical analysis - General instructions (referenced for sampling and general lab practice).
Keywords: ISO 5890, manganese ores, silicon content, gravimetric method, silica determination, laboratory method, analytical procedure, ISO 4297.
