Overview
ISO 6154:1989 - Chromium ores - Preparation of samples describes standardized methods for preparing samples of chromium ores for chemical composition and moisture determination. Applicable to natural and processed ores, the standard covers how to combine increments, divide samples, crush/grind, mix, and pre‑dry material so test samples are representative of a consignment. Annex A is an integral part of the standard.
Key topics and requirements
- Scope and objectives: Defines terms (lot, consignment, increment, sub‑sample, gross sample, test sample) and specifies sample preparation aimed at reliable determination of chromium content and moisture.
- Precision requirement: Sample preparation precision shall be within ±0.5% in chromium or moisture content with 95% probability.
- Division methods: Describes approved methods for reducing sample mass:
- Manual increment division
- Manual riffle division (riffle divider)
- Coning and quartering
- Mechanical division
- Fixed‑rate and constant‑mass division approaches
- Combining increments: Procedures differ for mass‑basis vs time‑basis sampling. Rules determine when increments or sub‑samples may be combined into sub‑samples or a gross sample.
- Apparatus and handling:
- Crushers and grinders suitable for ore size/hardness (to be purged with material from the same source)
- Screens and sieves in accordance with ISO 565
- Riffle dividers sized to particle dimensions
- Drying ovens controllable to ≤ 105 °C for pre‑drying
- Shovels and mixers for increment division and homogenization
- Wet samples and pre‑drying: Pre‑drying by air or oven (below 105 °C) is permitted to facilitate preparation; moisture samples must be stored in airtight, non‑absorbent containers to prevent changes.
- Mixing and homogeneity: Mechanical or manual mixing to achieve homogeneity and reduce division errors.
- Practical limits: For increment and riffle methods the standard indicates applicability for samples with whole‑through sieve sizes below 22.4 mm; minimum numbers of increments are specified (e.g., gross sample 20, sub‑sample 12).
Applications and users
ISO 6154:1989 is used by:
- Mining operations and processing plants for quality control of chromium ores
- Assay and metallurgical laboratories preparing samples for chemical analysis and moisture testing
- Commodity traders, inspectors and customs laboratories verifying consignment specifications
- Standardization and compliance teams implementing consistent sampling workflows
Practical benefits include improved representativeness of test samples, reduced analytical bias, and reproducible results for chromium content and moisture.
Related standards
- ISO 6153:1989 - Chromium ores - Increment sampling (directly referenced)
- ISO 565:1983 - Test sieves (referenced for sieving requirements)
Keywords: ISO 6154:1989, chromium ores sample preparation, sample division methods, riffle divider, increment sampling, moisture determination, chemical analysis.
