494

THE COLLIERY GUARDIAN

March 8, 1918.

HEATING OF COAL IN PILES.*

By C. M. Young.

Bituminous coal piled in heaps or bins frequently
undergoes a process of spontaneous heating as the
result of the absorption of oxygen. It seems probable
that the first absorption of oxygen by coal which has
not previously been exposed to the air may occur as
a condensation or a combination of oxygen in some
form which does not result in the production of carbon
dioxide, but slow combustion soon begins. The
absorption of oxygen is accompanied by an increase
of temperature, and this by an increased rapidity of
absorption; hence the dangerous condition proceeds
from bad to worse, until the kindling point is reached,
unless the process is interrupted.

A dangerous rise of temperature can be prevented
by excluding oxygen, by increasing the bulk of coal in
proportion to its surface exposed, or by circulating
enough air to dissipate the heat produced. The
storage of coal, in practice, varies from almost com-
plete exclusion of oxygen, by storing under water, to
such freedom of access as exists when the coal is stored
in open piles.

Oxygen available for absorption by coal is supplied
by the air in the interstices between lumps and by
additional air which may enter the pile through circu-
lation. The size of the coal largely affects both of
these supplies; for if the fragments are small, the
spaces between them constitute a small percentage of
the total volume, and little oxygen will be available
unless the circulation of air brings in a fresh supply,
while with large fragments the percentage is relatively
large; circulation also is much easier through a pile of
coarse lumps. In the case of lump coal, although a
large amount of air may be present, the exposed sur-
face is comparatively small, and there is little oppor-
tunity for the absorption of oxygen to be so rapid as
to cause dangerous heating. Attempts have been
made to prevent heating by allowing a sufficient circu-
lation of air to carry off the heat generated; obviously
this method cannot be applied to fine sizes nor mixed
sizes.

When storing coal at the University of Illinois, an
attempt has been made to use so much fine coal and
to pack it so thoroughly as to prevent circulation of
air, while also reducing the original air in the pile so
as to prevent heating. This method has been fairly
successful, but in some cases the piles have heated. An
investigation made when a pile was opened for the
removal of portions which had begun to heat indicated
that heating had occurred only in those parts of the
pile which contained comparatively small proportions
of fine coal.

To confirm the impression given by the appearance
of the pile, samples of coal were taken from the spots
where heating was evident, and from neighbouring
regions in which there was no evidence of heating.
These samples were then sized on screens ranging from
2 in. to | in. round hole, giving the following results:

Heated region. « Unheated region.

Size. (------------A--------r <---------A-------

In.	Per cent.	Cum. per cent.	Per cent.	Cum. per cent.
Over 2		0'0	.	—	<•0	—
1-2		....	32*6	’.	32'6	6'3	6-3
i-1		....	36*4	690	..	22'9	...	29'2
				12'2	81'2	...	24'8	...	54'0
	7*4	..	..	88'6	...	18'5	...	73'5
Below |		....	11*4	.. 100'0	...	27'5	... 100'0
				 ■					—	—
	100 0	—	100'0	—

It appears from this examination that the portions
of the pile in which fine sizes were present in largest
proportion did not contain sufficient oxygen to heat
the coal to any noticeable extent. The close packing
had also so obstructed circulation that little fresh
oxygen could have been brought in even if the temper-
ature had been raised to such an extent as to favour
circulation of air. This indicates that one compara-
tively safe way to store coal is to use enough of the
fine sizes to occupy the space as completely as possible,
and to pack the coal tightly in order that the air space
may be reduced and the circulation of air restricted.
Apparently the most dangerous condition exists when
the coal is of such sizes as to present a large aggre-
gate surface for absorption, and, at the same time,
leave sufficient air space to provide the oxygen required
for heating; this condition is found in a loosely packed
pile of mixed sizes.

* Paper read before the American Institute of Mining
Engineers.

LETTERS TO THE EDITORS.

The Editors are not responsible either for the statements
made, or the opinions expressed by correspondents.

All communications must be authenticated by the name
and address of the sender, whether for publication
or not. No notice can be taken of anonymous
communications.

As replies to questions are only given by way of published
answers to correspondents, and not by letter, stamped
addressed envelopes are not required to be sent.

Improvement in the head-dress of

BREATHING APPARATUS.

Sirs,—I shall be glad if you will publish the following
notes in your paper for the benefit of everybody
concerned.

At Newdigate Colliery,' on October 8, 1916, an
accident occurred to a man wearing a self-contained
breathing apparatus (oxygen type). It was suggested
at the time that the mouthpiece used with the apparatus
was not satisfactory, inasmuch as, when wearing a
mouthpiece, it would be quite easy for a man, by
dropping the lower jaw, to break the joint between his
mouth and the mouthpiece, Further, that these mouth-
pieces might be used satisfactorily for a million times
or more, and then a wearer might forget himself

through becoming interested in exploration work, etc.’
and indulging in too much “ rescue conversation.” He
would thus be liable to breathe the outside atmosphere,
and if this was poisonous the ultimate result would be
collapse. It has also been stated that, in the event of a
man being unconscious whilst wearing a self-contained
breathing apparatus, there would be a tendency to drop
the lower jaw, and outside atmosphere would be
inhaled.

To get over this difficulty, a suggestion was made to
add to the mouthpiece a chin strap to prevent the lower
jaw from dropping.

The next accident was the recent one at the Minnie
Pit, North Staffs., and in this case it was brought in
evidence that the nose clip was continually knocked off
the wearer’s nose, thus at once allowing the outside
atmosphere to be breathed. It was further said that
several members of the brigade were overcome, and no
doubt this was due to the nose clips being knocked off,
and also to too much “ rescue conversation.”

The goggles worn by men wearing self-contained
breathing'apparatus have not been a success. There is
always the ”isk of irritant gases getting between the
goggles and the face, owing to the difficulty of fitting
to faces of different shapes.

I wish to suggest a way to overcome the liability of
accidents of this kind occurring. Many persons will
have seen and inspected the latest gas masks as used by
the Army. Have you ever tried fitting the face mask
part, which contains goggles and nose clip, on to the
mouthpiece of self-contained breathing apparatus of the
liquid air and oxygen types ? I have tried one, and am
of the opinion that the face is effectively sealed
against the outside atmosphere. The wearer'holds the
mouthpiece exactly as on the apparatus used at presents
The mask is so made that the goggles attached to it can
be wiped in the event of any steam getting on them.
The nose clip attached to the inside of the mask is used
exactly as at present, and, as far as my experiments go,
even if the nose clip or the mouthpiece came [off, no
outside atmosphere would be breathed. I suggest this
as a means of getting over the difficulties mentioned
above.

I am writing this information with the idea of drawing
the attention of all rescue station officials, and I shall
be glad to hear from any of them as to their opinions on
this matter.

Frederick P. Mills, F.S.I., M.I.M.E.

Durham and Northumberland Collieries

Fire and Rescue Brigade,

The Rescue Station,

854, Scotswood-road, Newcastle-upon-Tyne,

March 6, 1918.

CAS ANALYSES ON BOILER PLANTS.

A writer in Cheap Steam, mentions as a source of
error in making analyses with the Orsat apparatus,
that the pyrogallic acid solution, when old, loses
its absorbing power had been reduced, chiefly in
the time limit, so that the residue (supposed to
contain only CO and N), passes into the Cu2012
and further absorption takes place, this being put
down as CO. Now it is well known that Cu2Cl2
solution will absorb oxygen almost as readily as pyro-
gallic acid, hence any oxygen not completely absorbed
by the pyrogallic acid will be absorbed in the Cu2Cl2
and it is likely that in many cases the CO found is
really oxygen. Under certain conditions too, an
alkaline solution of pyrogallic acid may give off
small amounts of CO, which are afterwards absorbed
in the Cu2 and Cl2, and then taken as having been
present in the original flue gas.

To overcome these difficulties phosphorus may be
used for the absorption of the oxygen, the sticks being
melted under water, re-cast into sticks about | in.
diameter, and cut the correct length to fill up the
absorption burette of the Orsat, and covered with
water. The buretter should be enclosed in a blackened
box, so as to exclude light when not in use, a door
at the front enabling the water level to be seen
when making the test. Phosphorus is a most efficient
absorbent of oxygen, when the temperature is kept
correct. Below 60 degrees F. the absorption slows
down, and at 75 degrees F. the phosphorus softens, so
it is necessary, in order to obtain the quickest results,
to work at from 60 degrees to 65 degrees F. During a
long experience, it was always found possible to obtain
these conditions without trouble.

OBITUARY.

The death is announced of Mr. Thomas Barton, aged 72,
of Osborne Vale, Orrell, Wigan, a well-known colliery
official in the Wigan coal field. Mr. Barton held important
positions in connection with the Pemberton Collieries for
nearly 40 years.

Coal for Coking.—The importance of chemically investi-
gating the coking and manufacturing qualities of South
Yorkshire coals was suggested by Prof. W. G. Fearnsides,
of the University of Sheffield, in a lecture before the Shef-
field Society of Metallurgists and Metallurgical Chemists,
Dr. W. H. Hatfield presiding over a good attendance. Prof.
Fearnsides discussed the available resources of coal, and
more particularly of coking coal, within a radius of 25 miles
of Sheffield. He pointed out that the change in the char-
acter of the Barnsley seam as it passed from the north,
about Wakefield, to the south, about Mansfield. In the
north it made good coke, and would also carry a mixture of
other coals which were less good as coking coals. About
Sheffield it would make good coke, but it was “ touch and
go ” as to whether it made good coke or not. The boun-
dary line bet ween the coking and non-coking qualities came
just about the Great Central Railway, between Sheffield and
Worksop. South of that line it did not coke. A discus-
sion took place on the points raised.

Notes from the Coal Fields.

[Local Correspondence.]

South Wales and Monmouthshire.

Patent Fuel Makers and the Controller—The Shipping
Facilities at Newport — Increased Cost of Output—
Colliery Owners as High Sheriffs—War Effect on Rail-
way Traffic—Protest by Exporters—Miners' Candi-
dates for Parliament—Extensions at Blaenavon.

Patent fuel manufacturers of this district sent a deputa-
tion to the Coal Controller, and discussed with him certain
difficulties as to labour and the price of material, the pur-
pose being to increase production, and so utilise larger
quantities of the small coal, for which, at the present time,
there is no market.

The Controller has arranged that neutral vessels working
under time-charter to France and Italy under limitation of
freight rate shall be supplied with bunker coals or. the same
terms as vessels of the Allies, namely—at the schedule
prices.

The Brecon and Merthyr Railway serves the section of
coal field on the border of Monmouthshire and Glamorgan
which is in process of rapid development. It was stated
at the shareholders’ meeting that special capital outlay had
been entailed at Bedwas in order to provide facilities for
dealing with the traffic at the colliery there; and, with
regard to the new Gelli pits, it was mentioned that the
output was increasing satisfactorily — one pit furnishing-
600,000 tons per annum and the other 400,000 tons. It is
noteworthy, as showing how the Rhymney Valley has
become populated owing to colliery developments, that
the statement showed an increase of 40,000 passengers
carried during 1917, as compared with 1913, notwithstand-
ing the 50 per cent, increase in fares.

The new chairman of the South Wales and Monmouth-
shire Wholesale Coal Factors’ Association is Mr. F.
Hathway (of Messrs. Cory Brothers and Company), in
succession to Mr. Horatio Kendrickand Mr. Hathway
will also serve on the Central Advisory Committee which
assists the Coal Controller.

There is a general movement to utilise more fully the
canals of South Wales, one evidence being the taking over
of certain of these by the Government.

In the course of the proceedings at the shareholders’
meeting of Consolidated Cambrian Limited, it was stated
that the increased cost of the output of large coal due to
the war wage was no less than 2s. 3d. per ton; and,
inasmuch as 70 per cent, of the output is large, the effect
upon the company was very great.

Mr. J. A.'Jones, the new High Sheriff for the county
of Glamorgan, is a director of Watts, Watts and Company,
also of the United National Collieries, and of Burnyeat,
Brown and Company. He has occupied the position of
president of the Cardiff Chamber of Commerce, and also
that of chairman of the South Wales and Monmouthshire
Coal Freighters’ Association. Mr. Jones is one of the
referees for dealing with appeals in connection with the
excess profits duty.

Mr. Evan Jones, who is High Sheriff of Cardiganshire
for the coming year, has been connected with the coal
trade in the western area for many years, chiefly in the
neighbourhood of Llanelly. He is the owner of collieries
at Trimsaran and elsewhere, and is also a director of the
Rhos, the Carway, and other collieries.

At Pontypridd County Court, a collier employed by the
Naval Company claimed 8s. Id. in respect of lost time due
to non-supply of timber which was needed for support of
his working place. The evidence on his behalf was that
the stall was unsafe pending the arrival of more timber,
and that he had informed the fireman on the previous
evening that he would be unable to work unless supplied.
For the company, it was contended that the plaintiff’s
working place was not unsafe, and the timber had been
sent in before 11 o’clock; and evidence was given that his
output for the day was up to the average. The judge
awarded 4s. damages.

The case of Davies v. Powell Duffryn Company has been
carried to the House of Lords, and as it deals with the
question of subsidence, it has widespread interest in this
area because of the experience of the large number of
miners who are the owners of the houses they occupy. In
the case referred to, a workmen’s institute in the Aberdare
Valley is concerned, and there are special circumstances
arising out of the ancient character of a lease which will
come under consideration. House owners, however, are
watching it with the greatest of concern, because the ques-
tion comes up time after time in different parts of the dis-
trict. For example, at a meeting of the Trades and Labour
Council in Abertillery, a statement was made showing
what action had been taken by the local District Council,
and it was said that the question of subsidence had become
very serious in that area, for many houses have been
greatly damaged. The speaker urged that those who really
caused the subsidence should be held legally responsible,
but stated that the local Council were not able to do any-
thing until it could be proved that their own property had
been damaged.

The Western Gas Coal Company has taken the minerals
underlying about 1,000 acres in the Llanmorlais district;
and the combination of interests in this new undertaking
includes leaders in the tin-plate and steel industry of the
district—among them Mr. T. J. Williams, M.P. for
Swansea District; Mr. Morgan Thomas, of the Broad Oak
Colliery Company; Mr. H. Folland, of the Grovesend Steel
Company; Mr. George Rowe, Upper Forest; and Mr. D.
Williams and Mr. J. Webborn.

The Neath and Brecon directors informed the share-
holders at their annual meeting of facts which show the
serious effect of short-time working due to lack of shipping.
There had been a loss in coal tonnage of 363,000 tons, as
well as a considerable falling-off ip the number of workmen
travelling to and from the collieries. The coal carried in
1916 was 919,611 tons, but last year only 556,718 tons,
whereas in 1913 the total was as high as 1,322,576 tons.
The number of workmen carried in 1917 was 223,344, as
compared with 364,808 in 1916.

Official intimation has now been made that exporters
will be deprived of the one-third of 5 per cent, brokerage
on freight—this to be paid over by the exporter to the
owners of the collieries, coke ovens, or patent fuel works
from which the fuel is shipped. The Coal Controller
issued his instructions under date March 2, and accom-
panied them with a letter which states that his new Order
does not affect the arrangement in the case of shipment to
France and Italy in neutral vessels (under which the excess
of brokerage charge over the charge based on the limitation
freight for British and Allied vessels is remitted to the
buyer). The outcry raised by exporters against the Order
has been intensified, because it means to them a serious
reduction in earning power, and it follows the restriction