ISO 12739:2006

Overview

ISO 12739:2006 specifies an analytical procedure - the ion‑exchange / EDTA titrimetric method - for the determination of the mass fraction of zinc in zinc sulfide concentrates. The method is applicable to concentrates containing 11 % to 62 % zinc and covers reagents, apparatus, sample preparation, the ion‑exchange separation, EDTA titration and reporting. The standard includes precision statements, blank tests and normative annexes for resins, sample drying and related procedures.

Key topics and technical requirements

• Scope and applicability: Designed specifically for zinc in zinc sulfide concentrates (11–62 % Zn).
• Principle: Dissolve a representative test portion in acids, adjust acidity, selectively adsorb zinc onto a strongly basic anion‑exchange resin, remove interferences, elute zinc with an ammonia/ammonium chloride solution and determine zinc by EDTA titration at about pH 5.5–5.7.
• Reagents and indicators: Analytical‑grade acids, ammonia/ammonium chloride eluent, EDTA standard solution (0.1 mol/L), xylenol‑orange and para‑nitrophenol used for end‑point/pH adjustment.
• Apparatus: Class A volumetric glassware, precision balance, ion‑exchange columns and resin (details and typical column dimensions in Annex A).
• Sample preparation: Air‑equilibrated test samples per ISO 9599; procedures for dissolving, dealing with acid‑insoluble residues and preparing predried test portions (Annex B).
• Quality control and precision: Requires duplicate determinations where possible, reagent blanks, titration factor determination for EDTA, and procedures for precision, trueness checks and interlaboratory performance (precision annexes).
• Safety: The standard warns about hazardous chemicals and advises following appropriate laboratory safety and regulatory limits.

Applications and who uses it

• Mining companies and concentrator labs performing zinc analysis for product quality control and metallurgical accounting.
• Analytical laboratories providing assay services for zinc sulfide concentrates.
• Metallurgists and process control engineers who need reliable, standardized zinc assays for process optimization and material valuation.
• Regulatory bodies and auditors requiring traceable, repeatable zinc mass‑fraction determinations.

Practical benefits include a reproducible, standardized workflow for selective zinc separation (via ion‑exchange) and robust quantification (EDTA titration), making comparisons between laboratories and batches consistent.

Related standards

Normative references cited in ISO 12739:2006 include:

• ISO 9599 - hygroscopic moisture in sulfide concentrates (sample prep)
• ISO 3696 - laboratory water quality
• ISO 385, ISO 648, ISO 1042, ISO 4787 - laboratory volumetric glassware and use/testing guidance

Keywords: ISO 12739, zinc sulfide concentrates, determination of zinc, ion‑exchange EDTA titration, zinc analysis, ion‑exchange resin, EDTA titrimetric method, concentrate assay.