THE COLLIERY GUARDIAN

AND JOURNAL OF THE COAL AND IRON TRADES.

Vol. CV.

FRIDAY, FEBRUARY 7, 1913

No. 2719.

THE DETERMINATION OF WATER IN COAL.

At the Eighth International Congress of Applied
Chemistry, held in New York September 4 to 13,1912,
Dr. R. Lessing, Ph.D., presented a report on “The
Determination of Water in Coal.” This report, of
which the full text is given in this and succeeding
issues of the Colliery Guardian, represents the result of
the labours of a sub-committee appointed by the
International Committee on Analyses to consider the
“Standardisation of Methods of Determining Water in
Coals and other Fuels, and in Minerals.” It is necessary
fib observe that the report was prepared by Messrs. G. T.
Holloway and J. H. Ooste, respectively president and
vice-president of the sub-committee, after consultation,
where possible, with other members of the sub-com-
mittee. Messrs. G. N. Huntly and J. H. Coste Have
dealt with the main conclusions of the sub-committee
in a paper read before the London section of the Society
of Chemical Industry on Monday, January 6, 1913, an
abstract of which has already appeared in the Colliery
Guardian.

The purview of the committee, as defined in a circular,
letter issued by the president in March 1911, includes
the consideration of:—

1.	The determination of moisture and of combined water,
including water of hydration and of crystallisation.

2.	The limits of accuracy possible or desirable in general
or special cases.

3.	The errors which would be introduced into other
portions of an analysis by the use of a defective method of
water determination—as, for instance, in the case of fuels,
where combined water, other than that actually determined,
would frequently be calculated out as hydrogen.

4.	Methods of general application or suitable only to
special cases or types of fuel or mineral, such as the effect of
the use, and limitations of the use, of so-called inert gases,
absorbents, vacuum drying, &c.

Indirect methods, such as the liberation of hydrogen by
the action of the water on calcium carbide, &c., may be
^considered under this heading.

5.	Methods of sampling, storing, and of generally dealing
with the material to be examined, so that errors other than
those due to the method of analysis shall be minimised.
This is important in all cases, but especially in connection
with coal and coke.

The following extract from the same letter usefully
ssupplements the above summary:—

“ It must be remembered that the term * water ’ includes
water in any form, free or combined, and not moisture only,
and that, although the methods of determining water in
mineral substances and in fuel are in many cases similar,
the conditions and requirements often differ considerably.

“ It may therefore prove advisable to consider the com-
mittee as being divided roughly into two sections—one for
fuel and one for minerals—although they will work in
conjunction and will furnish a joint report, possibly divided
into sections. Such members as are specially interested in
either branch may therefore, should they think best, devote
their attention mainly to such branch, although their
opinions are solicited also in connection with the other
^branch.

“ The determination of water is much more difficult, and
its technical and scientific importance is far greater than
appears at first glance. In fuel, its bearing on the
determination of hydrogen is extremely important, as the
combustion method, in which the water produced is
•calculated out as hydrogen, is commonly employed and is
often used in calculating out calorific values, <fcc.

“It would probably be correct to state that no really
accurate determination of hydrogen in coal has yet been
made, on account of the presence of combined water in the
mineral constituents, which ultimately, after being de-
hydrated, constitute the ash.

“ In the case of minerals, instances frequently occur where
generally accepted and apparently correct methods of
determining water prove to be inapplicable or to require
substantial modification.

" It is proposed that the report of the committee shall
include, not merely suggestions as to standard or special
methods, but general recommendations as to difficulties

which are still unsurmounted, and, so far as possible,
suggestions as to researches still remaining to be carried
out.”

It has not been found possible to cover the whole
ground of the reference to the committee, since, owing
to the fact that members have many other onerous duties
to perform, the amount of active experimental work done
has been limited. Nevertheless, a great deal of useful
work has been done on one most important branch of
the subject—the determination of water in coal—and
many useful suggestions on other matters have been
received. It is felt that the hope expressed in the
President’s circular that “ the committee’s report should
thus possess a value beyond that belonging to a mere
statement of the results obtained by its members, as, in
addition to suggesting standard methods of conducting
determinations of water and reporting results, it should
provide members of the profession with the keynote for
further research,” has, to a not inconsiderable extent,
been fulfilled.

Owing to the great preponderance of the work on
coal, it has been found necessary to confine the report
to the consideration of fuel, although much is directly
applicable to minerals ; and it is hoped that the members
and others will not only continue their work on fuel, but
will carry out researches in connection with minerals on
the above and other lines. The suggestions which have
been received regarding minerals have been too few and
too scattered for inclusion in this report, but show the
desirability of continuing the work and of the issue of
another report relating especially to minerals or the
publication of individual papers dealing with that most
important subject.

The work done has convinced those who have drawn
up the report that the recommendations embodied in it
can only be considered as of a tentative character and
by no means as indicating anything like finality.

The distinction, by analytical methods, between water
present as “ moisture,” “ water of combination,” and
“ water of crystallisation ” offers great difficulty, in
view of the varying conditions under which different
substances part with water present in the two latter
forms, and of the fact that the amount of water present
in the somewhat indefinite form of moisture appears to
be fairly sharply defined by the nature of the sub-
stance with which it is associated and the atmospheric
conditions prevailing at the time.

I. The Determination of Water in Coal.

On the suggestion of several members of the com-
mittee, a series of six samples of coal, marked 1 to 6,
ranging from an anthracite to a coal containing over
12 per cent, of sulphur, were sent to members who were
able to do experimental work for this report. They did
not cover the range which had been desired; but short-
ness of time rendered it necessary to send what was
available.

The samples sent out were prepared as follows :—

A quantity of the coal was ground in a Krupp ball-mill
and sifted through the 100-mesh standard I. M. M. sieve
having ^n- apertures. The coal thus prepared was
left exposed for some days in shallow trays so as to be
thoroughly air-dried under atmospheric conditions. Lots of
about 200 grammes of each sample were tinned off, 30 tins
of each sample being charged and sealed at the same time.
At uniform intervals during such charging, small glass tube
samples were taken and immediately sealed with the blow-
pipe. Twelve such tubes were taken from each of the six
samples, and some of them have been kept as reference
samples; the remainder have been tested as described in
section 5 of this part of the report.

The lever top tins had been previously tested and
found to be practically but not absolutely airtight. The
lids, after being forced into place, were therefore sealed
by means of rubber solution which has been proved
harmless and effective, and safer and better than
soldering. The samples sent out to each member of
the committee may be relied upon as being identical,
and as truly representative of the air-dried coals.

Many different types of grinder, in addition to the
ball-mill, were tried, including the ordinary coffee-mill
type and disc grinders, but the ball-mill was actually
employed, as less loss of water was experienced. Even
though three large disc grinders were used, two cooling
while the other was in use, considerable loss of water
occurred, and no method of grinding, except in a sealed
vessel, appears to overcome this objection. This point
was brought out in the report of the American Chemical
Society Committee.

The following table shows the approximate amounts
of moisture, volatile matter and ash in the samples:—

Sample number.

1.	2.	3.	5.	6?

Per	Per	Per	Per	Per	Per

cent.	cent.	cent.	cent.	cent.	cent.

Moisture............. 3	...	10	...	8	...	6	...	7	...	8

Total volatile matter
ex water............ 5	...	35	...	34	...	23	...	33	...	27

(ex sulphur)

Ash ................ 8	...	3|	...	4|	...	37	...	8|	...	10

These figures are extremely rough, and are merely
given as an indication of the type of coal.

No. 1 is an anthracite from South Wales.

No. 2 is from the Ten-yard or Thick coal seam of South
Staffordshire (England), which, in many respects, resembles
a lignite, and which extends under the whole of South
Staffordshire. It has never yet been coked in practice. As
mined, it contained 10 or 11 per cent, of water, 5 per cent,
of hydrogen, and 13 per cent, of oxygen.

No. 3 is from the Kilburn seam of Leicestershire
(England), and is a coking coal largely used for general
and household purposes.

No. 4 is a coal from South America, and is interesting in
connection with moisture determination on account of its*
high sulphur content (4’2 per cent, volatile and 8 2 per cent
non-volatile). No pyrites is visible or can be washed out, but
the coal rapidly weathers and develops free H2S04 and
FeS04. It contains 35 per cent. C and 3 per cent. H, and
has a calorific value of about 7,000 B.Th.U. Its ash contains
about 47 per cent. FeaOs, 17 per cent. AlaO8, 35 per cent.
SiOa, only 0 72 per cent. S, and less than 0’5 per cent, of
CaO or NgO. As might be expected, it clinkers badly, but
it is used locally owing to the high cost of imported coal.

No. 5 is an ordinary bituminous coal from Leicestershire.

No. 6 is a somewhat less bituminous coal from the south-
east of Scotland.

Members of the sub-committee were asked to
determine the moisture in the coals sent to them :—

1.	By the “ American standard ” method:

(a) Heating for one hour in a toluene or similar
bath.

(5) Heating for two hours in a toluene or similar
bath.

2.	By the method ordinarily employed by them.

3.	By a vacuum method if 2 be not a vacuum method.

(See sections of this report 1—3).

Several members experimented with other methods,
which in this report are included under section 4.

The results obtained by members using the various
methods follow under the sectional headings indicated
above. A list of the members who undertook this work
is appended. The best thanks of the reporters are due to
these gentlemen, who, by their efforts, have assisted in
advancing the important question at issue at least a few
steps nearer a final solution. The Roman numeral
after a name indicates the results in the following
tables for which the member or members may be
responsible:—E. R. Andrews (XII.), C. O. Bannister
(XVI.), H. Baucke (III.), W. T. Burgess (X.), Staff of
Messrs. Schneider and Co., Le Creusot (XIII.), E. J
Constam (XV.), J. H. Coste (XII.), H. F. Hills (IV.),
G. N. Huntly (VII.), M. Huybrechts (XIV.), A.
McArthur Johnston (IX.), L. L. De Koninck (XIV.),*
G. Lacombe (I.), R. Lessing (VIII.), 0. Nicolardot (II.)
W. Pollard (XI.),f W. E. F. Powney (XII.),J Dr. Prager

i (—), W. Rosenhain (V.). C. A. Seyler (VI.).

| * (Two names) worked together.

| f Assisted by Mr. E. G. Radley. Results published by
permission of the Director of H.M. Geological Survey.

I X (Three names) worked together.