Overview
SIST ISO 10258:2018 specifies two validated titrimetric methods for the determination of copper content in copper sulfide concentrates in the range 15% to 50% (m/m). Both methods use sodium thiosulfate titration of iodine liberated from the reaction between iodide and copper(II). Method 1 (Long iodide method) includes a separation step (precipitation of copper sulfide) before titration; Method 2 (Short iodide method) titrates directly without copper separation.
Key topics and technical requirements
- Scope and range: Determination of copper content in copper sulfide concentrates from 15% to 50% (m/m).
- Two titrimetric procedures:
- Method 1 (Long iodide method) - decomposes sample, removes As/Sb/Sn, separates copper by precipitation as CuS, dissolves precipitate and titrates liberated iodine with sodium thiosulfate.
- Method 2 (Short iodide method) - decomposes sample, removes As/Sb/Sn, eliminates iron interference and titrates directly without prior Cu separation.
- Key reagents: sodium thiosulfate (standard volumetric solution), potassium iodide, ammonium hydrogen difluoride, hydrobromic acid, nitric and sulfuric acids, soluble starch indicator.
- Standardization: Sodium thiosulfate solution is standardized against high-purity copper metal; standardization conditions (sample volume, KI mass, temperature) must match analytical runs.
- Apparatus and instrumentation: Class A volumetric glassware, analytical balance (0.1 mg), platinum crucibles; AAS (atomic absorption spectrometer) for optional verification and ICP-AES as optional instrumentation.
- Sampling and test portions: Recommended test portion masses given (e.g., 0.8 g for 15–25% Cu, 0.4 g for 25–50% Cu). Test sample preparation per ISO 9599; predried test portions procedure in Annex A.
- Quality control: Blank tests, duplicate determinations (minimum), precision and trueness checks, and acceptance flowsheet (Annex B). Precision details and formulae are provided (Annex C).
Practical applications and users
SIST ISO 10258:2018 is intended for:
- Analytical and assay laboratories in mining, concentrator and metallurgical operations.
- Quality control and certified testing for copper concentrate trading and shipment.
- Third‑party inspection and regulatory compliance testing.
Primary users: analytical chemists, metallurgists, assay laboratory technicians, and QC managers who require a standardized titrimetric method for accurate copper assay in sulfide concentrates.
Related standards
Normative references cited include:
SIST ISO 10258:2018 provides a practical, reproducible titrimetric approach for copper assay in concentrates, useful for routine laboratory analysis, shipment certification, and process control.