ISO 10258:2018

Overview

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

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:

• ISO 385, ISO 648, ISO 1042, ISO 4787 (volumetric glassware and testing)
• ISO 9599 (hygroscopic moisture determination for analysis samples)

ISO 10258:2018 provides a practical, reproducible titrimetric approach for copper assay in concentrates, useful for routine laboratory analysis, shipment certification, and process control.