756

THE COLLIERY GUARDIAN

October 11, 1918.

AUXILIARY VENTILATION OF COAL
MINES.

By J. Fox.

For trial headings and general exploration work, there
is not much doubt about the efficiency of auxiliary
ventilation, provided the method adopted is the one
that will best suit the particular seam or district that
is about to be worked. The employment of the mo>t
suitable system of auxiliary ventilation often saves a
considerable amount of time and trouble (and time in
mining operations always means expense) in such
headings, from the fact that considerably longer
distances can be driven without so many spouts or
thirlings as have to be driven by the ordinary methods
of ventilation. It matters not whether they are trial
headings or actual workings, ventilation with safety
and economy is always the first consideration. Trial
headings, more often than not, are driven in the rock,
especially if the measures are dipping or rising, so as to
cut any coal seams that are supposed to exist in the
vicinity. Much of this depends, as mentioned pre-
viously, on the inclination of the strata through which
the headings are being driven.

Auxiliary ventilation is resorted to with much success
when opening out new districts in old colleries, especially
when such new extensions are far removed from the
downcast shaft, and more so if the seams to be opened
out lie at a high elevation from the main intakes of the
older parts of the mine; and practice proves that the
satisfactory ventilation of such workings constitutes a
very difficult problem. In many instances new explora-
tion districts are driven in what is practically a maiden
mine, and if such be the case their situation is often
favourable for deleterious gases to be given off and
accumulate, whilst at the same time they are most
unfavourably situated for the supply of adequate quan-
tities of fresh air to render the above conditions harm-
less, and to comply with the Coal Mines Regulation
Act.

downs and falls occur somewhere in the workings
between the intake and return, especially if the break-
down occurs at some distance from the latter, because
the air current has a compressive action up to the point
of the fall or breakdown. Again, when extending the
headings in seams that are likely to give off gases of
some kind, one always gets better results with a blowing
current striking the back of the headings than with an
exhaust, for the practical reasons that one cannot get
the air pipes or brattices close enough up to the cuttings
for the current to strike against the back of the
workings, which being new are always giving off some
kind of either fiery or deleterious substances. With an
electric exhaust auxiliary ventilation one has many
proved doubtful points, and a very few practical and
economical ones.

MINING INSTITUTE OF SCOTLAND.

A general meeting of the Mining Institute of Scot-
land was held on Saturday, October 5, in the Heriot-
Watt College, Edinburgh. Mr. D. M. Mowat, Coat-
bridge, the president of the institute, occupied the
chair, and the attendance was quite representative
when regard is paid to the travelling restrictions in
these times. The following gentlemen were at the
outset admitted to the membership: Messrs. W.
Armour, mine manager, Prestwick; F. McGinty,
mining contractor, Shettleston; and A. Mack, mining
engineer, Coatbridge (student member).

The Occurrence of Coking Coal.

Discussion was resumed on the paper read at a
previous meeting by Mr. R. W. Dron, Glasgow, on
“ The Occurrence of Coking Coal in Scotland.”

and boxes, under the circumstances in which they
were used, were likely to give less trouble than any
other material. The author was to be commended
for his perseverance, because the undertaking looked
such a serious one that he (Mr. Kirkby) would pro-
bably have felt disposed to give it up as a bad job.

Further discussion of the paper was adourned till
the meeting of the institute to be held in Glasgow.

The Economy of Briquetting Small Coal.

Mr. John A. Yeadon (Leeds) thereafter read a
paper on “The Economy of Briquetting Small Coal”
(see p. 767).

Discussion.

The President enquired if the author had made
briquettes from coke breeze without any mixture of
coal at all.

Mr. Yeadon exhibited several samples of briquettes,
including one containing no coal whatever, being made
up of coke breeze and pitch. He explained that the
sample in question contained 8 per cent, of pitch.

Mr. Peter Milligan (Arniston Collieries) said this
was a subject to which he had personally given a good
deal of consideration, but the difficulty he had
experienced lay in the moisture to be found in the
usual duff coal taken from the washers. If there was
any practical method of drying the duff sufficiently, or
anything of that kind, his firm might see its way to
go on the lines of briquetting. It was well known
that briquetting was quite a sound commercial propo-
sition if they were able to manufacture briquettes
from this washer material he had alluded to at a
price that would pay all round.

Mr. Yeadon explained that the Manor Powis Coal
Company in Stirlingshire were intending to make

K

litre

+ = position of exhaust fan. x — position of blower.

Fig. 1.—Unsatisfactory Ventilation by Exhaust, Remedied
by Blowing.





x = position of fans.

Fig. 2.—^Long-distance Auxiliary Ventilation.



For such cases as mentioned above, auxiliary ventila-
tion will, if adopted on sound principles, give results
that will certainly prove satisfactory, both as regards
safety and economy. All the practical and theoretical
experience that can possibly be obtained should always
be taken into consideration before deciding on any
particular method; and the points in question should
be—Shall the method of ventilation be exhaust or
blowing? Shall the ventilator be fixed on the intake,
or on the return of the district, so that the best and
safest results can be obtained ? Will it be possible to
keep the auxiliary fan constantly running ?—if not,
what provisions will have to be adopted for week-ends
and stoppages through any breakdowns of machinery or
other causes ? What will be the motive power to drive
such fan ?

Either compressed air or electricity would have to be
used. The former, if already installed at the mine, is
safer than electricity, especially if an exhaust system of
ventilation be adopted, as, in that case, the ventilator
would have to be placed on the return side of the
workings, and, under the above-mentioned conditions,
there would be no risks or responsibilities from sparking,
fusing or fire in case the ventilation failed.

But if the system decided upon were electrically driven
the trouble would be very great, especially if the
district became fouled through the breakdown of the
machinery. Neither would one get such efficient venti-
lation as with a blowing system in any auxiliary system
of ventilation.

In exhaust auxiliary ventilation, the probabilities are
that the loss in leakages from long lines of air troughs
or brattices through doors and stoppings will be much
greater than with a blowing system, whereas with an
electric-driven exhaust ventilation, one can enumerate
the advantages on one hand, and on the other hand the
disadvantages are numerous.

From practical experience, it is far safer and more
economical to instal a blowing system of ventilation,
which would mean fixing the fan, etc., on the intake
side of the district, so that in case of any breakdowns
or electrical mishaps, such as electric machinery is
sometimes subject to, there will be no danger of the
return current coming in contact with the faulty
machinery, as would be the case if the electric power
was placed on the return side of the workings. By
fixing the ventilator on the intake side, one is far more
certain of a good current of air in the headings and in
all places difficult to ventilate, than with the exhaust
system, and one is more favourably placed when break -

Mr. James Hamilton (Glasgow) said that the author
suggested the possibility of coking coal being pro-
duced from the action of an igneous rock on a coal
seam. If this be the origin, it suggested the possi-
bility of coking any seam of coal. The only effect of
an igneous rock in a seam lying below it at least
must be a change by heat. There was no possibility
of gases affecting the constitution of the coal seam as
might happen if the igneous rock lay below the seam.
Therefore what could be done by nature in this way
lent encouragement to the hope that the same result
might be attained by the manufacturing process. No
doubt nature took longer to do its work. There was
no real comparison between the two processes, but
the same intensity of heat through similar gradations
over a shorter period of time might artificially produce
what nature did by the slower process, and thus allow
of coke from any coql seam. The discussion was
closed and the author thanked.

The Repair of a Circular Shaft of Small Diameter.

The meeting thereafter took up the discussion of
the paper by Mr. Stewart Chambers on “The Repair
of a Circular Shaft of Small Diameter.”

The President observed that this was a most prac-
tical paper dealing with a small shaft which had a
big difficulty. To his mind, it was a type of paper
which was of great value to the members of the insti-
tute. While the .shaft itself was, as he had said, a
small one, the difficulties connected with the repairing
of it were both very real and serious. The shaft, which
was only 6| ft. in diameter, collapsed, and the small
hole widened out to a large one, some 20 ft. or 25 ft.
in diameter. The effect of the collapse was to disclose
a dangerous and ugly hole, and the problem was to
get. the shaft relined without incurring any great
risk to the workmen from falling debris. They were
greatly indebted to the author for the full and clear
explanation of the somewhat unique manner in which
he had surmounted the difficulties.

Mr. Richard Kirkby (Wemyss) said it seemed to
him that the author had done the job so thoroughly
and successfully that there was little room for criti-
cism at all. Mr. Chambers was indeed to be congratu-
lated on his success. His efforts showed great persis-
tence and thoroughly good engineering. Personally, he
had wondered when he read the paper if some other
material could not have been used to take the place
of the barrels and boxes referred to in the paper. In
the end • he came to the conclusion that the barrels

their briquettes entirely from this washed coal, and
his firm were installing, in addition to the usual
briquetting plant, a proper furnace for drying this
particular coal. He might add that so long as the
washed coal, the ‘‘slimes,” or whatever it might be,
did not contain more than 10 per cent, of moisture it
could be made into very satisfactory briquettes.

The President remarked that more than one-half
of the output of coal in Scotland contained 10 per
cent of moisture—that was to say, the coal in its
natural state. Most of the coal measures coal con-
tained about 10 per cent, of moisture.

Mr. Yeadon said this point in regard to moisture
was rather interesting. Coal had been sent to his firm
from Leicestershire, and they had been somewhat
astounded to observe that the analysis revealed the
presence of 13 per cent, of moisture in the coal itself.
As they were asked to quote a price for a plant cap-
able of dealing with that coal, they did so. The col-
liery owners, however, did not accept the estimate,
for the reason—and they were not to be blamed for
that—that they doubtless thought they were going to
get a better plant for 25 per cent, less in cost. They
got their plant, but he had since been informed by the
manager that the briquettes could not be sent into
the market at all owing to the abnormal moisture in
the coal and the fact that far too much pitch was
required to make them. It might, he thought, be of
interest to the members of the institute to know that
within the past two years his firm had installed four
briquetting plants in France, and at the moment they
had enquiries for two more plants. Two plants had
been erected in Italy and another had gone to Norway.
Then, only five weeks ago, two plants had gone out
to Japan. These facts showed that the people outside
of Britain, and even outside Europe, were alive to the
importance in these times of briquetting small coal.
In South Wales, as was well known, there were large
accumulations of anthracite duff. He did not sup-
pose there was much of that in Scotland. It was
somewhat interesting, then, to note that the anthra-
cite duff from South Wales was at the present time
being sent out to France, where it was being manufac-
tured into ovoid briquettes at Bordeaux. Further,
within the past two or three weeks ovoid briquettes
made from anthracite duff had been sent into Leeds
from South Wales, the intention being to see if the
householders there would care to use them. He had
tried some of these ovoid briquettes in his own home,
and found they made quite a hot fire. Indeed, so