Overview
ISO 4295:1988 specifies laboratory methods for the determination of aluminium content in manganese ores and concentrates. It provides two validated procedures: a photometric method (Method A) for low-to-moderate aluminium levels and an oxine gravimetric method (Method B) for higher aluminium contents. The standard is a technical revision of the original edition and is intended to be read alongside ISO 4297 (general chemical analysis instructions) and the ISO 4296 sampling standards.
Key topics and requirements
- Scope
- Method A (photometric): applicable to aluminium contents 0.1 to 1.5% (m/m).
- Method B (oxine gravimetric): applicable to aluminium contents > 1.5% (m/m).
- Principles
- Method A: formation of a coloured complex between aluminium and chromazurol‑S (molecular ratio 1:3) in acetate buffer (pH 6–7) with polyvinyl alcohol and ascorbic acid to suppress interferences; measurement by spectrophotometer/photocolorimeter at ~610–620 nm.
- Method B: separation of silica and other matrix components, precipitation of aluminium as an oxinate (quinolin‑8‑ol chemistry), followed by ignition/fusion and gravimetric determination.
- Reagents and apparatus
- Analytical‑grade reagents and distilled water required. Key reagents include chromazurol‑S, polyvinyl alcohol, hydroxylammonium chloride, zinc chloride, boric acid, oxine (quinolin‑8‑ol), sodium thiosulfate, and fusion salts.
- Ordinary laboratory glassware plus a spectrophotometer or photocolorimeter for Method A.
- Procedure essentials
- Detailed sample decomposition (acid digestion, evaporation, fusion of residues), separation of interfering iron, blank tests, calibration graphs (Method A) and duplicate determinations are mandated.
- Quality control
- Carry out analyses in duplicate, perform blank determinations, and follow the permissible tolerances for parallel results specified in the standard.
Applications and users
- Routine aluminium assay of manganese ores and concentrates in:
- Mining and mineral processing laboratories
- Metal and alloy feedstock quality control
- Commercial assay and certification labs
- Research and geochemical laboratories assessing ore grade and impurities
- Practical uses: compliance with supply specifications, process control, product grading, and material characterization before metallurgical processing.
Related standards
- ISO 4297 - Manganese ores and concentrates: Methods of chemical analysis - General instructions
- ISO 4296-1 and ISO 4296-2 - Manganese ores: Sampling and sample preparation
Keywords: ISO 4295:1988, manganese ores, aluminium determination, photometric method, chromazurol‑S, oxine gravimetric method, quinolin‑8‑ol, analytical methods, laboratory procedure, chemical analysis.
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