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Ref. NO.: ISOlR 589 - 1967 (E)
IS0
i N T E R N AT1 O N AL ORGAN I ZATl O N FOR S TAN DAR DI ZAT I O N
IS0 RECOMMENDATION
R 589
DETERMINATION OF TOTAL MOISTURE IN HARD COAL
1st EDITION
July 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 589, Determination of Total Moisture in Hard Coal, 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 1950 and led, in 1961, to the
adoption of a Draft IS0 Recommendation.
In October 1962, this Draft IS0 Recommendation (No. 553) was circulated to all the IS0
Member Bodies for enquiry. It was approved, subject to a few modifications of an editorial nature,
by the following Member Bodies:
Australia Republic of South Africa
Greece
Austria India Romania
Belgium Iran Spain
Brazil Italy Sweden (for Method A)
Chile Japan Switzerland
Czechoslovakia Netherlands Turkey
Denmark New Zealand United Kingdom
France Poland U.S.S.R.
Germany Portugal Yugoslavia
Two Member Bodies opposed the approval of the Draft:
Sweden (for Methods B and C)
U.S.A.
The Draft IS0 Recommendation was then submitted by correspondence to the IS0
Council, which decided, in July 1967, to accept it as an IS0 RECOMMENDATION.
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ISOlR 589 - 1967 (E)
IS0 Recommendation R 589 July 1967
DETERMINATION OF TOTAL MOISTURE IN HARD COAL
1. SCOPE
This IS0 Recommendation describes three methods of determining the total moisture content
of hard coal. Two of the methods are applicable in all cases, but the third should be used only
for coals which are not susceptible to oxidation.
The moisture content of coal is not an absolute value and conditions for its determination have
to be standardized. Results given by the different methods recommended should be comparable
within the limits of tolerance quoted.
2. PRINCIPLE
2.1 Method A (for all hard coals)
The coal is heated in a flask under reflux conditions with toluene or xylene (see Note 1 , page 10).
The moisture from the coal is entrained by the toluene or xylene vapour and carried to a
condenser fitted with a graduated receiver. The water then separates in the receiver, to form
the lower layer, whilst the excess toluene or xylene is returned to the distillation flask by
means of an overflow. The moisture in the coal is calculated from the mass of the sample
and the volume of water collected.
2.2 Method B (for all hard coals)
The sample is dried in an oven at a temperature of 105 to 110 OC in a current of nitrogen and
the moisture calculated from the loss in mass.
2.3 Method C (only for hard coals not susceptible to oxidation, see Note 2, page 10)
The sample is dried at a temperature of 105 to 110 OC in air and the moisture calculated from
the loss in mass.
3. SAMPLE
3.1 Samples for the determination of moisture will be received in sealed air-tight containers.
3.2 The sample mass will not be less than 300 g; for methods A and B the maximum particle size
will not exceed 3 mm; for method C, which is normally applicable to samples with a maximum
particle size of about 20 mm, the sample mass in kilogrammes will not be less than 0.06 times
the maximum particle size in millimetres.
3.3 During the course of its preparation the sample may have been air-dried, in which case a
formula is used to calculate the total moisture content (see Note 3, page 10).
3.4 Before commencing a determination, either by method A or method By or in accordance with
Note 8, page 10, of method C, mix the sample thoroughly in a closed container for at least one
minute, preferably by mechanical means.
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ISOlR 589 - 1967 (E)
4. METHOD A
4.1 Reagents
All reagents should be of analytical reagent quality and distilled water should be used
throughout.
4.1.1 Toluene (see Note 5, page 10). Boiling point 110 OC.
4.1.2 Xylene (see Note 5, page 10). Boiling range 135 to 140 OC.
4.2 Apparatus
All graduated apparatus should be of the best analytical quality available, and the balance
used should be sensitive to 100 mg.
4.2.1 Distillation flask, of minimum capacity 500 ml.
4.2.2 Condenser, of 200 mm minimum length, fitted with an extended lip to direct the distillate
into the receiver without touching the sides (see Note 4, page IO).
4.2.3 Receiver, for the condensed water, graduated in tenths of a millilitre (see Note 4, page 10).
An overflow tube connected to the receiver or to the lower portion of the condenser
permits the return of condensed toluene or xylene to the distillation flask. The condenser
may be fitted to condense either an upward flowing or downward flowing vapour stream.
The condenser, receiver and flask are fitted together by means of ground joints.
4.2.4 Glass tubing. Pieces of glass tubing 5 mm in diameter and 5 mm long, with sharp edges
(or other suitable means of preventing violent ebullition).
4.2.5 Spray tube. A glass tube through which toluene or xylene can be supplied to wash down
the inner surface of the condenser (only required when an upward flow condenser is
employed).
4.3 Procedure
4.3.1 Test. Weigh to the nearest 0.1 g about 100 g of the sample (see Note 6, page IO) and
transfer to the dry distillation flask. Add 200 ml of the toluene (4.1.1) or of the xylene
(4.1.2) in such a way that any coal adhering to the neck or sides of the distillation flask
is washed down by the reagent. Place two or three pieces of glass tubing (4.2.4) in the
distillation flask to prevent violent ebullition, fill the receiver with the toluene (4.1. I)
or the xylene (4.1.2) and assemble the apparatus. Heat the distillation flask and keep
the contents boiling briskly.
Continue the distillation until no further water collects in the graduated receiver. If
an upward condenser is used, wash down any drops of water adhering to the inner surface
of the condenser or to the upper walls of the receiver with the reagent employed, using
the spray tube. Continue the distillation for a sufficient time to ensure that any water
washed back into the distillation flask has been carried over into the receiver. Read the
volume of the distillate after any cloudiness has dispersed.
4.3.2 Calibration. Standardize the apparatus by distilling a series of known volumes of water,
accurately measured, e.g. by a microburette, covering the range of moisture contents in
the fuels likely to be encountered. Plot a graph, showing the millilitres of water added
against the scale reading of the water in the receiver, and use it to correct the volume
of water obtained in each test.
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ISOlR 589 - 1967 (E)
4.4 Calculation and reporting of result
If nz = mass of coal taken, expressed in grammes,
= corrected volume of water, read from graph, expressed in millilitres,
VC
M = moisture in the coal analysed, per cent,
then
vc x 100
M= (assuming that 1 ml of water has the mass of 1 g).
m
The result obtained represents:
(1) the percentage of total moisture in the sample, if the latter has not previously
either
been air-dried ;
or (2) the percentage of residual moisture if the sample has previously been air-dried
(see Note 3, page 10).
The final result should be expressed to the nearest 0.1 %, stating that the determination has
been carried out by method A and whether toluene or xylene has been used.
5. METHOD B
5.1 Reagents
5.1.1 Nitrogen. Dry and containing less than 30 parts per million of oxygen (see Annex A,
page 11).
5.1.2 Desiccant. Either fresh or freshly regenerated silica gel or other desiccant, for use in the
desiccator.
5.2 Apparatus
The balance used should be sensitive to 1 mg.
5.2.1 Nitrogen oven. An oven capable of being maintained at a temperature within the range
105 to 110 OC and with provision for passing a current of dry oxygen-free nitrogen
through it at a rate sufficient to change the atmosphere 15 times per hour. A suitable oven
is illustrated in Figure, page 11.
5.2.2 Weighing vessels. Shallow vessels, of silica or glass, with ground edges and fitted with
ground-on covers, or of non-corrodible and heat resistant material with well-fitting lids.
The diameter of each vessel should be such that the weight of the coal layer does not exceed
0.3 g/cm2 for a 10 g sample.
5.3 Procedure
Weigh to the nearest 0.01 g a clean dry empty vessel and its cover and spread uniformly
into it not less than 10 g of sample. Weigh the covered vessel and its contents to determine
the mass of coal taken.
Place the cover in a desiccator and heat the uncovered vessel in the oven at a temperature
OC until constant in mass (see Note 7, page 10). Replace the cover, cool rapidly
of 105 to 110
on a metal plate for 10 minutes, transfer to a desiccator and weigh after a further 10 minutes.
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ISOIR 589 - 1967 (E)
5.4 Calculation and reporting of result
If m1 = mass of empty vessel plus cover, expressed in grammes,
= mass of vessel plus cover plus sample before heating, expressed in grammes,
m2
= mass of vessel plus cover plus sample after heating, expressed in grammes,
m3
M = moisture in the coal analysed, per cent,
then
m2 - m3
M= x 100
m2 - ml
The result obtained represents:
either (1) the percentage of total moisture in the sample, if the latter has not previously
been a
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