ISO 8343:1985

Overview

ISO 8343:1985 specifies a gravimetric method for the determination of silicon content in ferronickel, applicable to concentrations from 0.2 % to 4.0 % (m/m). The method details principle, reagents, apparatus, sampling and sample preparation, step‑by‑step procedure, calculation and test reporting. It is intended for routine laboratory analysis where a reliable gravimetric measurement of silicon is required.

Key topics and technical requirements

• Principle: Dissolve the test portion in nitric and perchloric acids, dehydrate silicon to insoluble silica, filter and calcine the precipitate, volatilize silica with hydrofluoric + sulfuric acids to remove silica interferences, and determine silicon by mass difference using a conversion factor (SiO2 → Si = 0.467).
• Applicable range: 0.2–4.0 % silicon (m/m).
• Sample sizes (typical):

  • 1 % Si: 2.00 g test portion

  • 0.25–1 % Si: 4.00 g test portion
  • < 0.25 % Si: 10.00 g test portion
• Reagents: Analytical grade acids including nitric, perchloric (70 %), hydrofluoric, hydrochloric, sulfuric and diluted solutions; distilled or equivalent water.
• Apparatus: 600 ml high‑form beaker, platinum crucible (~40 ml), muffle furnace capable of 1100 °C, desiccator, appropriate filtration equipment.
• Sampling & preparation: Laboratory samples usually in granules, millings or drillings. If oily, clean with high‑purity acetone; riffle if particle sizes vary.
• Safety warnings: Strong emphasis on hazards - hydrofluoric acid and fuming perchloric acid are highly dangerous; use appropriate fume‑hoods and safety procedures. Thorough washing of filters is required to remove perchloric acid before incineration.
• Precision: A limited interlaboratory study is reported. Typical repeatability and reproducibility values are provided in the standard (repeatability r in the order of 0.013–0.039 %; reproducibility R in the order of 0.014–0.087 % for tested levels).

Applications and users

Who uses ISO 8343:1985:

• Metallurgical laboratories performing chemical analysis of ferronickel for quality control and specification compliance.
• Producers and processors of ferronickel and nickel alloys who need validated silicon measurements.
• Third‑party testing and certification labs requiring standardized gravimetric methods. Practical applications include routine QC of raw ferronickel charges, verification of alloy composition, and support for material acceptance testing.

Related standards

• ISO 5725 - Precision of test methods (referenced for determination of repeatability and reproducibility).
• National or industry sampling standards (for agreed sampling procedures where disputes arise).

Keywords: ISO 8343:1985, ferronickel, determination of silicon, gravimetric method, silicon content, gravimetric analysis, HF, HClO4, quality control, metallurgical laboratory.