ISO 12743:2021

Overview

ISO 12743:2021 - Copper, lead, zinc and nickel concentrates - Sampling procedures for determination of metal and moisture content - establishes standardized sampling procedures for concentrates to provide reliable samples for chemical analysis, physical testing and moisture determination. The fourth edition (2021) defines preferred and reference sampling methods for concentrates from moving streams and stationary lots, excludes slurry sampling, and requires preparation steps (e.g., crushing large agglomerates >10 mm). Where concentrates oxidize or decompose, a common representative sample for both moisture and chemical analysis is required (see ISO 10251).

Key topics and technical requirements

• Sampling theory and variance: total variance, sampling-stage estimation, simplified and interleaved-sample methods for assessing precision and bias.
• Sampling schemes: establishing intervals, number and mass of increments, and lot/subsample constitution to meet representativity targets.
• Preferred vs reference methods:
  • Moving-stream sampling is preferred (falling-stream and cross-belt samplers described).
  • Stopped-belt sampling is the reference method against which mechanical and manual procedures are compared.
• Mechanical and manual sampling:
  • Design and placement of sample cutters, cutter speed, safety and bias-minimization measures.
  • Mass-basis and time-basis systematic sampling, stratified random sampling, and procedures for manual full- and partial-stream cuts.
• Sample handling:
  • Crushing of large agglomerates (>10 mm) before further processing, procedures for division, comminution, mixing and subsampling.
• Special situations: sampling from grabs, trucks, railway wagons, hoppers, bags/drums, stockpiles; limitations (slurry excluded).
• Quality control: routine checking, interleaved sampling provisions, and steps to minimize and detect systematic errors.

Applications and who uses it

ISO 12743:2021 is essential for practical workflows that require accurate metal assays and moisture content in concentrates:

• Mine operators and concentrator plants performing QA/QC on copper concentrates, lead concentrates, zinc concentrates and nickel concentrates.
• Metallurgists, assay laboratories and laboratory managers establishing sampling protocols and sample preparation.
• Sampling equipment manufacturers and conveyor/system designers implementing compliant mechanical sampling systems (falling-stream, cross-belt, stopped-belt).
• Traders, inspectors and regulators needing defensible, unbiased sampling reports for transactions, compliance and dispute resolution.

Related standards

• ISO 10251 - referenced for combined moisture and chemical analysis sampling when oxidation/decomposition is a concern.
• ISO 12743:2021 should be used alongside other relevant International Standards for laboratory analysis and material handling to ensure end-to-end sampling integrity.

Keywords: ISO 12743:2021, sampling procedures, copper concentrate sampling, moisture determination, stopped-belt sampling, falling-stream sampler, cross-belt sampler, mechanical sampling, manual sampling, sampling variance.