ISO 4280:1977

INTERNATIONAL STANDARD.
INTERNATIONAL ORGANIZATION FOR STANDARDIZATION l MEXAYHAPOflHAR OPl-AHM3AWW l-IO CTAHAAPTM3AUMM *ORGANISATION INTERNATIONALE DE NORMALISATION
Cryolite, natura1 and artificial, and aluminium fluoride for
- Determination of sulphate content - Barium
industrial use
sulphate gravimetric method
Cryolithe, naturelle et artificielle, et fluorure d’aluminium 2 usage industriel - Dosage des sulfates -
AMhode gravimktrique 6 l’e’tat de sulfate de baryum
First edition - 1977-11-15
Ref. No. ISO 4280-1977 (E)
UDC 661.8 : 553.634 + 661.862.362 : 546.226 : 543.21
sufphates, gravimetric analysis.
Descriptors : aluminium ores, aluminium fluorides, cryolite, Chemical analysis, determination of content,
Price based on 3 pages
FOREWORD
ISO (the International Organization for Standardization) is a worldwide federation
of national Standards institutes (ISO member bodies). The work of developing
International Standards is carried out through ISO technical committees. Every
member body interested in a subject for which a technical committee has been set
up has the right to be represented on that committee. International organizations,
governmental and non-governmental, in Iiaison with ISO, also take part in the work.
Draft International Standards adopted by the technical committees are circulated
to the member bodies for approval before their acceptance as International
Standards by the ISO Council.
International Standard ISO 4280 was developed by Technical Committee
ISO/TC 47, Chemistry, and was circulated to the member bodies in March 1975.
lt has been approved by the member bodies of the following countries :
Austria
India Sweden
Belgium
Israel Switzerland
Brazil Thailand
I taly
Bulgaria Mexico Turkey
Egypt, Arab Rep. of Poland United Kingdom
France Romania U.S.A.
Germany South Africa, Rep. of U.S.S. R.
Hungary Spain
No member body expressed disapproval of the document.
@ International Organization for Standardkation, 1977 l
Printed in Switzerland
INTERNATIONAL STANDARD ISO 428001977(E)
Cryolite, natura1 and artificial, and aluminium fluoride for
industrial use - Determination of sulphate content - Barium
sulphate gravimetric method
1 SCOPE 5.7 Silver nitrate, 5 g/l nitric acid Solution.
This International Standard specifies a barium sulphate Dissolve 0,5 g of silver nitrate in a little water, add IO ml
gravimetric method for the determination of the sulphate of nitric acid Solution, p approximately 1,40 g/ml, dilute to
content of cryolite (natura1 and artificial) and aluminium 100 ml with water and mix.
fluoride for industrial use.
6 APPARATUS
2 FIELD OF APPLICATION
Ordinary laboratory apparatus, and
The method is applicable to products having sulphate
contents, expressed as sulphur trioxide (SO,), equal to or
6.1 Platinum dish, flat bottomed, diameter approximately
greater than 0,l % (mlm).
75 mm, height approximately 30 mm, with a platinum lid.
3 REFERENCES 6.2 Platinum crucible, diameter approximately 30 mm,
height approximately 30 mm.
I SO 16 19, Cryolite, natura1 and artificial - Preparation and
s torage 0 f tes t samples.
6.3 Electric oven, capable of being controlled
at 110*2”C.
ISO 2925, Aluminium fluoride for industrial use -
Prepara tion and storage o f test samples.
6.4 Electric furnace, capable of being controlled
at 850 k 20 “C.
4 PRINCIPLE
Alkaline fusion of a test Portion with a mixture of sodium
7 PROCEDURE
carbonate and boric acid. Extraction of the fused mass with
perchloric acid Solution and precipitation of the sulphate
WARNING - Carry out the evaporation of the perchloric
ions with barium chloride in an acidified medium.
acid under a weil ventilated fume hood or in a fume cup-
Filtration of the precipitate, calcination at 850 “C and
board in the absence of ammonia or nitrous vapours.
weighing of the residue.
7.1 Test Portion
5 REAGENTS
Weigh, to the nearest 0,000 1 g, in the platinum dish (6. l),
about 1 g of the dried test Sample (see 3.3 of ISO 1619 or
During the analysis, use only reagents of analytical grade
2.3 of ISO 2925).
and only distilled water or water of equivalent purity.
5.1 Sodium carbonate, anhydrous.
7.2 Determination
5.2 Boric acid.
7.2.1 Fusion of the test Portion
5.3 Perchlorit acid, p approximately 1,67 g/ml, about
Add 3,75 g of the sodium carbonate (5.1) and 1,25 g of the
70 % (mlm) solution.
boric acid (5.2) to the platinum dish (6.1) containing the
test Portion (7.1). Mix carefully and cover the dish with the
5.4 Hydrochlorit acid, approximately 6 N Solution.
lid.
5.5 Sulphuric acid, p approximately 1,84 g/ml, about
Place the covered dish in the electric furnace (6.4),
96 % (mlm) Solution.
controlled at 850 + 20 ‘C, and maintain the dish at this
temperature for about 30 min. Prevent the dish from
touching the furnace shelf by placing it on a suitable
5.6 Barium chloride dihydrate (BaCl,.2H,O), 122 g/l
support.
Solution, approximately 1 N solution.
ISO 4280-1977 (E)
7.3 Blank test
7.2.2 Preparation of the test Solution
Carry out a blank test at the Same time as the
Remove the dish from the furnace and allow it to cool
determination, following the Same procedure and using
in air. Add 25 ml of the perchloric acid Solution (5.3) and
15 ml of water and, having replaced the lid, heat until the same quantities of all the reagents as used for the
determination, but omitting the test Portion.
the contents of the dish are completely dissolved. Remove
the lid and carefully wash any residue into the dish with
hot water. Gently evaporate the contents of the dish to
dryne
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