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IS0
I NT ERN AT1 ON AL ORGAN IZATl ON FOR STAN DA RD IZATION
IS0 RECOMMENDATION
R 625
DETERMINATION OF CARBON AND HYDROGEN
IN COAL AND COKE
BY THE LIEBIG METHOD
1st EDITION
October 1967
COPYRIGHT RESERVED
The copyright of IS0 Recommendations and IS0 Standards
belongs to IS0 Member Bodies. Reproduction of these
documents, in any country, may be authorized therefore only
by the national standards organization of that country, being
a member of ISO.
For each individual country the only valid standard is the national standard of that country.
Printed in Switzerland
Also issued in French and Russian. Copies to be obtained through the national standards organizations.
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BRIEF HISTORY
The IS0 Recommendation R 625, Determination of Carbon and Hydrogen in Coal and Coke
by the Liebig Method, was drawn up by Technical Committee ISO/TC 27, Solid Mineral Fuels,
the Secretariat of which is held by the British Standards Institution (BSI).
Work on this question by the Technical Committee began in 1952 and led, in 1958, to the
adoption of a Draft IS0 Recommendation.
This first Draft IS0 Recommendation (No. 236) was circulated in May 1958 to all the IS0
Member Bodies for enquiry. As the results of this consultation were not considered satisfactory
the Technical Committee presented a Second Draft IS0 Recommendation, which was circulated
to all the Member Bodies in October 1963 and which was approved, subject to a few modifications
of an editorial nature, by the following Member Bodies:
Argentina Germany Republic of South Africa
Australia Greece Romania
Austria India Spain
Belgium Italy Switzerland
Bulgaria Korea, Rep. of
Turkey
Canada Netherlands United Kingdom
Chile New Zealand U.S.A.
Czechoslovakia Poland U.S.S.R.
Denmark Portugal
Yugoslavia
One Member Body opposed the approval of the Draft:
France
This Second Draft IS0 Recommendation was then submitted by correspondence to the
IS0 Council which decided, in October 1967, to accept it as an IS0 RECOMMENDATION.
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UDC 662.6/.7 : 620.1 Ref. No. : ISO/R 625-1967/Al-1971 (E)
Amendment 1 - November 1971 - to IS0 Recommendation R 625-1967
Amendment 1
to IS0 Recommendation R 625 -1 967
DETERMINATION OF CARBON AND HYDROGEN
IN COAL AND COKE
BY THE LIEBIG METHOD
Section 3, REAGENTS
Delete the 3rd line of clause 3.1.
Delete clause 3.2.
Delete the 1st sentence of the Note.
Delete the 2nd line of clause 3.3.
Delete clause 3.4.
Accordingly renumber clauses 3.3 to 3.10.
Section 4, APPARATUS
Clause 4.1
Delete “or calcium chloride (3.2)”, “or potassium hydroxide (3.4)” and “or calcium chloride (3.2)” in the 3rd, 5th
and 6th lines.
Replace “3.3” by “3.2” in the 5th line.
Clause 4.3
Delete “or calcium chloride (3.2)” in the 3rd, 6th and 9th lines, and “or potassium hydroxide (3.4)” in the 8th line.
Replace “3.5” by “3.3” and “3.3” by “3.2” in the 5th and 8th lines respectively.
Section 5, PREPARATION OF THE APPARATUS AND BLANK DETERMINATION
Replace all the reference numbers 3.6 to 3.9 by 3.4 to 3.7 respectively.
BRIEF HISTORY
Amendment 1 to IS0 Recommendation R 625-1967, Determination of carbon and hydrogen in coal and coke b-, the
Liebig method, was drawn up by Technical Committee lSO/ï’C 27, Solid mineral fuels, the Secretariat of which is held
by the British Standards Institution (BSI).
hL
Draft IS0 Recommendation No. 1937 was drawn up on this subject, and was circulated to all the IS0 Member Bodies
for enquiry in April 1970. It was approved by the following Member Bodies :
Australia India Sweden
Belgium Iran Switzerland
Canada Italy Turkey
Chile Korea, Rep. of U.A.R.
Czechoslovakia Netherlands United Kingdom
Denmark New Zealand U.S.A.
France
Poland U.S.S.R.
Germany Portugal
Yugoslavia
Greece South Africa, Rep. of
No Member Body opposed the approval of the Draft.
This Draft IS0 Recommendation was then submitted by correspondence to the IS0 Council, which decided to
accept it as AMENDMENT 1 to IS0 Recommendation R 625 -1 967.
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ISO/R 825 - lM7 (E)
IS0 Recommendation R 625 Octo ber 1967
DETERMINATION OF CARBON AND HYDROGEN
IN COAL AND COKE
BY THE LIEBIG METHOD
1. SCOPE
This IS0 Recommendation describes the Liebig method of determining the total carbon and the
total hydrogen in hard coal, brown coal and lignite, and coke; the results include the carbon in
the carbonates and the hydrogen combined in the moisture and in the water of hydration of
silicates. A determination of moisture is carried out at the same time and the appropriate correc-
tion is applied to the hydrogen value obtained by combustion. A determination of carbon
dioxide may also be made and the total carbon value corrected for the presence of mineral
carbonates.
2. PRINCIPLE
The sample is burned in a current of oxygen, the products of the incomplete combustion being
burned over copper oxide; all the hydrogen is converted to water and all the carbon to carbon
dioxide. These products are absorbed by suitable reagents and determined gravimetrically.
Oxides of sulphur are retained by lead chromate, chlorine by silver gauze and oxides of nitrogen
by granular manganese dioxide.
NOTE. - Oxides of nitrogen formed in the combustion would in the absence of precautions, be absorbed by the
soda asbestos and considered as carbon dioxide. The error in the carbon determination thus caused, of the order
of 0.2 % of carbon, is substantially avoided by the use of a guard-tube (see Fig. 1, page 9) in which the gases
pass through an annular space to allow oxidation of nitric oxide to nitrogen peroxide, which is absorbed by the
manganese dioxide.
If water is condensed in the first absorber, some nitrogen peroxide may dissolve in it and be considered as water.
Because of the conversion factor from water to hydrogen, the error in the hydrogen determination thus caused is
small, of the order of 0.05 % of hydrogen. This can be avoided only by heating the absorption tube to a
sufficient temperature to prevent condensation of water.
3. REAGENTS
All reagents should be of analytical reagent quality. Distilled water should be used throughout.
3.1 Magnesium perchlorate, anhydrous (anhydrone). Free from dust and within the size range
2.4 to 0.4 mm; preferably within the size range 1.2 to 0.7 mm (see Note below)
or, if magnesium perchlorate is not readily available,
3.2 Calcium chloride, anhydrous. Freshly prepared and of size range 1.2 to 0.7 mm.
NOTE. - Calcium chloride should be saturated with carbon dioxide before use; many varieties of anhydrone do
not need this conditioning treatment, but a new source should be checked in this respect before use. Regeneration
of magnesium perchlorate should not be attempted, owing to the risk of explosion. When exhausted the magne-
sium perchlorate should be washed down the sink with a current of water.
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ISO/R 625 - 1967 (E)
3.3 Soda asbestos. Size range 1.2 to 0.7 mm;
or, if soda asbestos is not readily available:
3.4 Potassium hydroxide. Pellet or stick form.
3.5 Manganese dioxide, granular. Dissolve manganese sulphate in water and boil the solution.
Make alkaline with dilute ammonia and add solid ammonium persulphate, in small portions,
to the boiling solution until precipitation is complete. Filter through a fast, hardened paper,
wash with water by decantation, then with dilute sulphuric acid and finally with water until
acid-free. Transfer the moist precipitate to a mortar and place in an oven until most of
the water has evaporated, but the powder is still damp. Press the mass into a cake with a
pestle, using firm pressure. Complete the drying, break up the cake cautiously and sieve to
separate the 1.2 to 0.7 mm size.
3.6 Copper gauze.
3.7 Copper oxide. Wire form.
3.8 Lead chromate. Fused, size range 2.4 to 1.2 mm.
Pure silver gauze. Approximately 10 meshes per centimetre, made of wire approximately
3.9
0.3 mm in diameter.
3.10 Oxygen, hydrogen-free. The oxygen should preferably be prepared from liquid air and not
by electrolysis. Electrolytically prepared oxygen should be passed over red hot copper
oxide before use to remove any trace of hydrogen.
4. APPARATUS
4.1 A purification train, for absorbing water vapour and carbon dioxide present in the oxygen.
Assemble the train using the following reagents in the order stated:
(I) Magnesium perchlorate (3.1) or calcium chloride (3.2) for absorbing water (see Note
below).
(2) Soda asbestos (3.3) or potassium hydroxide (3.4) for absorbing carbon dioxide.
(3) Magnesium perchlorate (3.1) or calcium chloride (3.2) for absorbing the water evolved
in the reaction between carbon dioxide and soda asbestos (see Note below).
The purification train should be large enough to render frequent recharging unnecessary
even with continuous use.
4.2 Combustion device
Furnaces. The combustion tube is heated by three furnaces, the lengths of which should
4.2.1
be specified by the standardizing authority in each country. For the 127 cm combustion
tube described in section 5, the following lengths are appropriate :
Furnace No. 1 to heat the boat and its contents to 925 "C - 24 cm.
Furnace No. 2 to keep the copper oxide section of the tube heated throughout to
800 "C - 47 cm.
Furnace No. 3 to cover the lead chromate and the roll of pure silver gauze and to heat
the former to about 500 "C - 21.5 cm.
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ISO/R 625 - 1967 (E)
A combustion tube of fused silica or suitable hard glass. The diameter of the tube and
4.2.2
the lengths of the various packings can be varied and should be specified by the stan-
dardizing authority in each country (see section 5).
4.2.3 A combustion bout of platinum, porcelain or fused silica, approximately 7 cm long.
An absorption train, for absorbing the water and carbon dioxide evolved by the combustion
4.3
of the sample. Assemble the train using the following reagents in the order stated:
(1) Magnesium perchlorate (3.1) or calcium chloride (3.2) for absorbing the water evolved
during the combustion (see Note below).
(2) Granular manganese dioxide (3.5) for absorbing oxides of nitrogen.
(3) Magnesium perchlorate (3.1) or calcium chloride (3.2) for absorbing the water evolved
from the manganese dioxide.
(4) Soda asbestos (3.3) or potassium hydroxide (3.4) for absorbing carbon dioxide.
(5) Magnesium perc
...