ISO 20292:2009 PDF

Overview

ISO 20292:2009 specifies a standardized laboratory method to assess the cryolite resistance of dense refractory bricks used in the production of primary aluminium. The test evaluates how refractory brick materials resist attack and infiltration by a molten cryolite mixture (cryolite with excess sodium fluoride) under controlled high-temperature conditions that simulate electrolyte exposure in aluminium electrolysis cells.

Keywords: ISO 20292:2009, cryolite resistance, dense refractory bricks, primary aluminium, refractory testing

Key topics and technical requirements

• Scope and principle
  • Measures resistance of dense refractory bricks to a molten cryolite/NaF mixture at 950 °C for 24 h in air.
  • Reaction and infiltration areas are quantified and described visually (photocopies/photographs).
• Sample preparation
  • Minimum two bricks from the batch; test pieces taken from different bricks.
  • Test crucible: bore of (57 ± 1) mm diameter and (40 ± 1) mm depth in a ~110 × 110 × 65 mm brick piece; lids ~10 mm thick.
• Test mixture and loading
  • Powder mix: 60% cryolite (Na3AlF6, ≥97% purity) and 40% sodium fluoride (NaF, ≥99% purity), particle size