ISO 6830:1986

Overview

ISO 6830:1986 specifies an EDTA titrimetric method for the determination of aluminium content in iron ores, concentrates and agglomerates (including sinter). The method is applicable to aluminium concentrations from 0.25 to 5.0 % (m/m). The standard covers principle, reagents, apparatus, sampling and sample preparation, detailed procedure, expression of results and test reporting, and includes three annexes (flowsheet and supplementary guidance).

Key topics and technical requirements

• Analytical principle: fusion of a predried test portion with a mixed flux (sodium carbonate + sodium peroxide), dissolution, removal of interfering elements (cupferron/chloroform extraction and hydroxide precipitation), complexation with disodium EDTA and back-titration of excess EDTA with a zinc standard volumetric solution using xylenol orange indicator. Ammonium fluoride is used to liberate EDTA bound to aluminium for final titration.
• Reagents and apparatus: lists of required reagents (EDTA, cupferron, chloroform, perchloric/nitric/hydrochloric acids, ammonium chloride, sodium hydroxide, acetate buffer, etc.) and common laboratory equipment including vitreous carbon or zirconium crucibles and burettes conforming to ISO specifications.
• Sampling and sample prep: laboratory sample of particle size minus 100 µm (minus 160 µm for ores with significant combined water or oxidizable compounds); predrying at 105 ± 2 °C per ISO 7764.
• Quality control: each analytical run must include a blank test and a certified reference material of the same ore type. The standard provides statistical controls for repeatability and between-laboratory reproducibility, including regression equations for permissible tolerances (e.g., repeatability and reproducibility expressed as functions of aluminium content).
• Calculation and reporting: formula for converting titration volume to % aluminium, rounding rules, and an oxide factor for converting Al to Al2O3 (factor: 1.8895). Test report content is specified.

Applications and users

• Use in mineral analysis laboratories, metallurgical and mining quality control, iron-ore concentrators and sinter plants to quantify aluminium contamination or beneficial alumina content.
• Applicable for product specification, process control, metallurgical balancing, and regulatory or contractual testing where ISO-conformant results are required.
• Beneficial to laboratory managers, analytical chemists, quality assurance personnel and standards compliance officers.

Related standards

• ISO 3081 / ISO 3082 / ISO 3083 (sampling and sample preparation for iron ores)
• ISO 7764 (preparation of predried test samples)
• ISO 3851 (laboratory burette requirements)
• Annexes A–C in ISO 6830 provide a flowsheet and additional guidance for result acceptance and statistical treatment.

Keywords: ISO 6830, aluminium content, iron ores, EDTA titrimetric method, titrimetric analysis, aluminium determination, sampling, repeatability, certified reference material.