ISO 21587-2:2007

Overview

ISO 21587-2:2007 defines wet chemical analysis methods for the chemical determination of aluminosilicate refractory products and raw materials. Published by ISO as Part 2 of the ISO 21587 series, this standard provides classical (non‑XRF) laboratory procedures as alternatives to the X‑ray fluorescence (XRF) fused‑bead method (ISO 12677). It covers determination of major and minor oxides commonly measured during refractory quality control and materials development.

Key analytes included:

• Silicon(IV) oxide (SiO2)
• Aluminium oxide (Al2O3)
• Iron(III) oxide (as Fe2O3)
• Titanium(IV) oxide (TiO2)
• Manganese(II) oxide (MnO)
• Calcium oxide (CaO)
• Magnesium oxide (MgO)
• Sodium oxide (Na2O)
• Potassium oxide (K2O)
• Chromium(III) oxide (Cr2O3)
• Zirconium oxide (ZrO2)
• Phosphorus(V) oxide (P2O5)

Key topics and requirements

• Sample dissolution and stock/blank solutions - Procedures reference Part 1 (apparatus, reagents, dissolution and gravimetric silica).
• Spectrophotometric methods - e.g., molybdenum blue for residual SiO2 (absorbance measured at 650 nm), 1,10‑phenanthroline for iron, permanganate absorption for manganese.
• Volumetric and titration methods - e.g., CyDTA (cyclic diethylenetriaminepentaacetic acid)–zinc back titrations for aluminium, cupferron solvent extraction for interfering metals, diphenylcarbazide for chromium.
• Flame photometry - specified for sodium oxide and potassium oxide determinations.
• Colourimetric/complexometric reagents - use of xylenol orange for zirconium, molybdenum blue for phosphorus, and other indicated indicators and buffers.
• Calibration, blank tests and calculations - the standard prescribes calibration graphs, blank controls and formulas for reporting mass fractions.
• Test reporting - requirements for the content of the analytical test report.

Applications and users

ISO 21587-2:2007 is practical for:

• Laboratory analysts performing quality control of refractory bricks, castables and raw materials.
• R&D and materials development teams in refractories, ceramics, foundry and metallurgy industries.
• Independent testing labs and academic researchers needing validated wet chemistry alternatives to XRF.
• Situations where XRF is unavailable, where complementary wet‑chemical confirmation is required, or for trace‑level determinations not suited to XRF.

Related standards

• ISO 21587-1:2007 - Apparatus, reagents, dissolution and gravimetric silica
• ISO 21587-3:2007 - ICP and AAS methods for refractory analysis
• ISO 12677:2003 - Chemical analysis by XRF (fused bead method)
• ISO 26845 - General requirements for wet chemical analysis and instrumental methods

Keywords: ISO 21587-2, wet chemical analysis, aluminosilicate refractory, XRF alternative, SiO2 Al2O3 Fe2O3, refractory quality control.