Overview
ISO 12744:2025 - "Copper, lead, zinc and nickel concentrates - Experimental methods for checking the precision of sampling" specifies standardized experimental procedures to quantify the precision of primary sampling, sample processing, chemical analysis, physical testing and moisture determination for copper, lead, zinc and nickel concentrates. Precision is expressed in terms of standard deviations and is intended for use with sampling procedures in ISO 12743. This third edition updates the evaluation method to use mean squared differences between duplicates, giving a better unbiased estimate of precision.
Key topics and requirements
- Scope: Precision checks for sampling, sample processing, analysis and moisture content determination of sulfide concentrates.
- Interleaved sampling: Pairs of interleaved samples (A and B) formed by diverting alternate increments are the basis for experimental checks.
- Sample numbers: Recommended sampling from more than 20 lots of the same concentrate type for reliable conclusions; minimum increments typically set at 2n (or n divided into two interleaved samples in routine checks).
- Sample processing methods: Three prescribed methods:
- Method 1: Divide each interleaved sample into two laboratory samples and analyse each in duplicate - allows separate estimation of sampling, processing and analysis precision.
- Method 2: Unequal division (two from A, one from B) with duplicates - provides separate estimates but with lower precision than Method 1.
- Method 3: One lab sample from each interleaved sample analysed in duplicate - yields analysis precision and the combined sampling+processing precision.
- Evaluation: Precision calculated from duplicate results using mean squared differences; results reported as estimated standard deviations (sampling S, processing P, analysis A, total T).
- Frequency and conditions: Regular precision checks are recommended, especially after equipment or procedure changes; all determinations run in randomized order by the same analyst on the same day using the same equipment.
Applications and users
ISO 12744:2025 is used for:
- Quality control and verification in assay laboratories and metallurgical labs
- Sampling validation for mining companies, concentrate producers and traders
- Contractual dispute resolution where precise measurement of metal and moisture content is required
- Audit, accreditation and internal QA programs that require documented precision estimates
Typical users: metallurgists, sampling engineers, laboratory managers, quality assurance personnel, and third‑party auditors.
Related standards
- ISO 12743 - Sampling procedures for metal and moisture content (primary reference)
- ISO 10258 - Copper sulfide concentrates - titrimetric determination of copper
- ISO 11441 - Lead sulfide concentrates - determination of lead
- ISO 12739 - (Referenced for analytical methods)
Keywords: ISO 12744:2025, sampling precision, copper concentrates, lead concentrates, zinc concentrates, nickel concentrates, interleaved samples, sample processing, standard deviation, analytical precision.
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