Materials for the production of primary aluminium — Dense refractory bricks — Determination of cryolite resistance

ISO 20292:2009 covers materials for the production of primary aluminium. ISO 20292:2009 specifies a method for the determination of the resistance of dense refractory bricks to cryolite melt with excess sodium fluoride.

Matériaux pour la production de l'aluminium de première fusion — Briques réfractaires denses — Détermination de la résistance de la cryolite

General Information

Status
Published
Publication Date
28-Apr-2009
Current Stage
9093 - International Standard confirmed
Start Date
26-Sep-2015
Completion Date
31-Dec-2020
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ISO 20292:2009 - Materials for the production of primary aluminium -- Dense refractory bricks -- Determination of cryolite resistance
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INTERNATIONAL ISO
STANDARD 20292
First edition
2009-05-15
Materials for the production of primary
aluminium — Dense refractory bricks —
Determination of cryolite resistance
Matériaux pour la production de l'aluminium de première fusion —
Briques réfractaires denses — Détermination de la résistance de la
cryolite
Reference number
ISO 20292:2009(E)
ISO 2009
---------------------- Page: 1 ----------------------
ISO 20292:2009(E)
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© ISO 2009

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ii © ISO 2009 – All rights reserved
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ISO 20292:2009(E)
Contents Page

Foreword ............................................................................................................................................................iv

1 Scope ......................................................................................................................................................1

2 Principle..................................................................................................................................................1

3 Sampling.................................................................................................................................................1

4 Reagents.................................................................................................................................................1

5 Apparatus...............................................................................................................................................1

6 Procedure...............................................................................................................................................3

7 Precision statement ..............................................................................................................................5

8 Test report..............................................................................................................................................6

Bibliography........................................................................................................................................................7

© ISO 2009 – All rights reserved iii
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ISO 20292:2009(E)
Foreword

ISO (the International Organization for Standardization) is a worldwide federation of national standards bodies

(ISO member bodies). The work of preparing International Standards is normally carried out through ISO

technical committees. Each member body interested in a subject for which a technical committee has been

established has the right to be represented on that committee. International organizations, governmental and

non-governmental, in liaison with ISO, also take part in the work. ISO collaborates closely with the

International Electrotechnical Commission (IEC) on all matters of electrotechnical standardization.

International Standards are drafted in accordance with the rules given in the ISO/IEC Directives, Part 2.

The main task of technical committees is to prepare International Standards. Draft International Standards

adopted by the technical committees are circulated to the member bodies for voting. Publication as an

International Standard requires approval by at least 75 % of the member bodies casting a vote.

Attention is drawn to the possibility that some of the elements of this document may be the subject of patent

rights. ISO shall not be held responsible for identifying any or all such patent rights.

ISO 20292 was prepared by Technical Committee ISO/TC 226, Materials for the production of primary

aluminium.
iv © ISO 2009 – All rights reserved
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INTERNATIONAL STANDARD ISO 20292:2009(E)
Materials for the production of primary aluminium — Dense
refractory bricks — Determination of cryolite resistance
1 Scope

This International Standard covers materials for the production of primary aluminium.

This International Standard specifies a method for the determination of the resistance of dense refractory

bricks to cryolite melt with excess sodium fluoride.
2 Principle

A mixture of fine powders (< 100 µm) of cryolite and sodium fluoride are allowed to react at 950 °C in a

furnace for 24 h in air, on a crucible-shaped test piece made of the dense refractory brick material to be

tested.

Reacted and/or infiltrated areas of brick material are calculated. Together with the calculation, a visual

description of the reaction extent is recommended and photographs should also be used to illustrate the

attack.
3 Sampling

Take a number of different bricks from within the batch to be tested. Take a minimum of two sample bricks to

prepare test pieces. The test pieces are taken from different bricks.
4 Reagents

4.1 Cryolite (Na AlF ) powder, with a minimum purity of 97 % mass fraction and a particle size < 100 µm.

3 6

4.2 Sodium fluoride (NaF) powder, with a minimum purity of 99 % mass fraction and a particle size

< 100 µm.

IMPORTANT — The electrolyte used in aluminium electrolysis will penetrate through the carbon block

materials and then into the refractory. It is essential that this electrolyte penetration be stopped by

reaction with the refractory. It is hence important to test the different refractory materials for

resistance towards penetration. This test correlates well with penetration in industrial cells.

5 Apparatus
5.1 Diamond saw, with water cooling.
5.2 Core drilling apparatus, standard drilling machine with water cooling.
© ISO 2009 – All rights reserved 1
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ISO 20292:2009(E)
5.3 Three drill pieces, to be mounted on the drilling machine:
a) a 50 mm diamond core drill that gives a (57 ± 1) mm hole;
b) a 30 mm core drill;

c) a 48 mm to 50 mm steel disk mounted on a stem, where pieces from a diamond core drill, that are 3 mm

high with the same radius of curvature as the disk, are glued on underneath (see Figure 1).

5.4 Furnace, capable of heating the test crucibles as required to (950 ± 5) °C.
5.5 Thermocouples, at least three, capable of measuring temperatures of 950 °C.

5.6 Drying cabinets, capable of drying the test crucibles as required at (110 ± 5) °C.

5.7 Photocopy machine.
5.8 Photocopy paper.
5.9 Balance, accurate to 0,01 g.

SAFETY PRECAUTIONS — During exposure, fluoride gas will be generated. The corrosive gasses will

react and accumulate in
...

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