ISO 806:2004

INTERNATIONAL ISO
STANDARD 806
Second edition
2004-10-15
Aluminium oxide primarily used for the
production of aluminium —
Determination of loss of mass at 300 °C
and 1 000 °C
Oxyde d'aluminium principalement utilisé pour la production de
l'aluminium — Détermination de la perte de masse à 300 °C et à
1 000 °C
Reference number
©
ISO 2004
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ii © ISO 2004 – All rights reserved

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
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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 806 was prepared by Technical Committee ISO/TC 226, Materials for the production of primary aluminium.
This second edition cancels and replaces the first edition (ISO 806:1976) together with ISO 803:1976, which
have been technically revised. This International Standard is based on AS 2879.1-2000 prepared by the
Standards Australia Committee MN/9, Alumina and Materials used in Aluminium Production, as a revision of
AS 2879:1986, Alumina — Determination of loss of mass at 300 °C and 1 000 °C.
Introduction
The objective of this revision is to incorporate sample preparation procedures, improve the description of the
method and to provide a method for determination of loss of mass by automatic procedures.

iv © ISO 2004 – All rights reserved

INTERNATIONAL STANDARD ISO 806:2004(E)

Aluminium oxide primarily used for the production of
aluminium — Determination of loss of mass at 300 °C and
1 000 °C
1 Scope
This International Standard specifies a method for the determination of loss of mass on heating of aluminium
oxide at 300 °C and further loss of mass on ignition at 1 000 °C. By industry convention, these mass losses
are often referred to as “moisture (MOI)” and “loss on ignition (LOI)” respectively.
This method is suitable for calcined alumina in the range 0,2 % to 5 % loss of mass at 300 °C and 0,1 % to
2 % loss of mass at 1 000 °C.
This method provides for samples to be treated on an “as-received” basis for determination of actual MOI and
LOI in alumina samples. To improve precision of analysis in cases where “as-received” results are not
required, samples can be “air-equilibrated” prior to analysis. “Air-equilibration” can greatly affect MOI results
and significantly alter LOI results. The “air-equilibration” procedure and its effects are discussed in Annex A.
Instrumental methods are also discussed.
2 Normative references
The following referenced documents are indispensable for the application of this document. For dated
references, only the edition cited applies. For undated references, the latest edition of the referenced
document (including any amendments) applies.
AS 2850, Chemical analysis — Interlaboratory test programs — For determining precision of analytical
method(s) — Guide to the planning and conduct
3 Principle
The test portion of aluminium oxide is dried at 300 °C for 2 h and the loss of mass is determined by mass
difference. The test portion is then ignited at 1 000 °C for 2 h and the further loss of mass is determined.
4 Desiccants
WARNING — Because of the risk of explosion, do not attempt regeneration of magnesium perchlorate
by oven drying. Magnesium perchlorate and phosphorus pentoxide are hazardous and reference
should be made to appropriate material safety information.
One of the following desiccants shall be used:
a) phosphorus pentoxide;
b) activated alumina;
c) magnesium perchlorate.
If alumina is to be used as a desiccant it shall be freshly activated by heating for 12 h at (300 ± 10) °C and
shall then be cooled for at least 4 h in the desiccator before use. The alumina shall be activated daily.
5 Apparatus
5.1 Vacuum desiccator (see Figure 1), containing an aluminium heat sink (5) with positions for four
crucibles and tray of desiccant.
Figure 2 shows a suitable design for a heat sink. A metal tray of approximate dimensions 150 mm diameter
and 30 mm depth and containing approximately 250 g of desiccant is suitable. The desiccator should be of
such dimensions that the free circulation of air is not restricted (see Figure 1 for a suitable configuration). The
desiccator lid inlet should also be fitted with a moisture trap containing a granular desiccant.
5.2 Platinum crucibles with lids, of 25 ml capacity and having approximate dimensions of 35 mm
diameter and 40 mm depth.
5.3 Electric oven, capable of being controlled at (300 ± 2) °C, and fitted with mechanical air circulation.
NOTE Ovens utilizing natural air convection are not likely to achieve the required temperature control.
5.4 Electric furnace, capable of being controlled at (1 000 ± 10) °C.
5.5 Balance, capable of weighing to the nearest 0,000 1 g.
5.6 Thermogravimetric instrument, if required (see Clause 11).
6 Sample handling and preparation
Aluminium oxide used for aluminium production is a mixture of phases, most of which are active and will
rapidly absorb moisture from the atmosphere. Consequently, great care needs to be taken to minimize
exposure to atmosphere.
Seal samples in an airtight container immediately after collection. Leave space in the container to allow tumble
mixing. Unless samples are prepared promptly and with a minimum of exposure to the laboratory atmosphere,
inaccurate values for both moisture content and loss on ignition on an “as-received” basis will result.
Tumble the sample bottle to mix the sample prior to analysis. Remove the test portion and seal immediately
after the test portion has been taken from it. Do not use any sub-sampling or mixing technique that involves
removing all the bottle contents.
7 Procedure
7.1 Preparation of crucible and lid
Prepare the crucible and lid as follows.
a) Heat the crucible and lid in the furnace (5.4) at (1 000 ±10) °C for 15 min.
b) Remove the crucible and lid from the furnace, place in the desiccator (5.1) and allow to cool for 10 min.
c) Weigh the crucible and lid and record the mass to the nearest 0,000 1 g (m ).
2 © ISO 2004 – All rights reserved
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