460

THE COLLIERY GUARDIAN

March 10, 1916

CURRENT SCIENCE

Automatic Starting Device for Hydraulic Ram.

At the North Nuggety Ajax Mine, Victoria, a 7 in.
hydraulic ram has been installed to replace a steam
pump. The principal feature of this ram is the auto-
matic starting device, in which, to ensure the pulse (or
dash) valve closing when the supply pond runs short,
■stopping the ram, and thus allowing pond to re-fill,
advantage is taken of the fact that air in the drive pipe
causes it to close at any time. A jin. pipe, leading
from the low level of the water in the pond, is carried
alongside the drive pipe to a point mid-way in its length,

f<p'



Di

AIR
CHAMBER

A. En/cnded-Spirted J
of Pulse Vafve

JB . p Pipe prom fag/i-
idc/ter level of
Supply poor!

C,	Ci, Balance lankc

D,	DI, Counfcrvre/jjhls

E,	Deflecting Buf/ic

F Ft . Fulcrums

G.G/ Levers

and connected, thus supplying air when water in the
pond gets too low for useful work, i.e., a variable
summer flow.

When the supply pond fills again, water flows through
pipe B into C, overbalancing D, when G strikes A, thus
opening pulse valve, which should start the ram work-
ing. . When C has emptied over H, filling C1? and over-
balancing DT, it causes baffle E to deflect water from
going into C. C\ remains down so long as the ram is
working, and splashing water into it, and over H, but,
being provided with holes in bottom, will empty if the
ram stops, and be overbalanced by Dn thus, allowing
water from B to again flow into C (which has returned
to its normal position), when the action is repeated,

This automatic device worked well during last dry
summer. One hour’s work of the ram cut out the pond
supply, which took three hours to fill again, and so on.
The lever arrangements were worked out by Mr. A. J.
Gloster, the battery manager.—Mining and Engineering
Review.

Spontaneous Combustion in Queensland Mines.

In a paper read before the Ipswich and District Mining
Institute, W. E. Lawrie, inspector of mines, deals with
the subject of spontaneous combustion in mines, with
special reference to the Bundamba district. The author
gives a resume of the results of investigations in other
parts of the world, and thereafter deals with the question
from a local standpoint. Gob fires are common in the
Ipswich and Bundamba districts, and, although not
exclusively, they have been mostly confined to the.
Aberdare seam, wThich is the highest workable seam in
the district, and in every case those fires have been
attributed to spontaneous combustion.

When the temperature of a place is noticed to rise
gradually, it will be evident that the heat is being
generated more quickly than the surrounding material
can absorb it, and as the temperature increases more air
will penetrate to the seat of oxidation or combustion, until
a stage ■ is frequently reached when the quantity of
oxygen becomes insufficient for the complete combustion
of the carbonaceous material. Mr. Lawrie does not agree
with the theory that heat acting on iron pyrites causes
sulphuretted hydrogen (H2S), or “stink damp,’’ to be
given off, having no doubt whatever that the gas which
gives this smell is really SO2 or sulphur dioxide, and
that it is this which gives that peculiar paraffin smell
which is so common to gob fires.

The general method of working the Aberdare seam,
and indeed any seam in -this district, is to cut up the
whole workable area into pillars, and extract a large
percentage of coal in the first operation, sometimes as
much as 75 per cent, being extracted in bonds, although
it is the average practice to take out between 50 per cent,
and 60 per cent. The Aberdare seam varies in thickness
from 6 ft. to as much as 64 ft. in the collieries working-
it. Three collieries work a 6 ft. sectionj two work a
15 ft. ■ section, one works a 15 ft. section and a 6 ft.
section, while still another works a 15 ft. section and
two 6 ft. sections. The thickness of cover varies from
50 ft. to 666 ft. In all of these collieries a considerable
thickness of coal and bands is left on the roof. In every
instance the method of working is extremely favourable
to spontaneous heating. A great amount of coal is

AND TECHNOLOGY.

thrown into the gob, adhering to the stone and shale
bands which the miner takes out. In some instances
there is sufficient of these bands to build packwalls .to
the roof and to stow a good bit of the gob, and in every
instance that the author has been able to investigate the
fire has always broken out in these gob heaps, the heaps
being generally in contact with a pillar, and always in
badly ventilated places. Many instances can be given
of the heating taking place in the discarded portion of
the seam, notably in Old Aberdare, Coolgardie, Boxflat,
Aberdare, and Fairbank collieries. Very soon the fire
attacks the pillars, and unless very great care is taken
in properly sealing it off, the pillar is very soon burnt
through.

A fire does not always take place in gob material.
When pillars are small they soon become crushed, dust
lodges in the creases made by the crushing, or the coal
falling from the pillars as they are crushed accumulates
at the bottom of the pillars, and in such cases sufficient-
heat may be generated spontaneously to start a fire if
other conditions are suitable, but so far it has never come
to the knowledge of the author that any of the fires in
this district have started in this way.

A number attribute the occurrence of gob fires to the,
large amount of timber left in and built round with the
coaly gob material. On a fire section being recently opened
in a local colliery, the exposed portion of most of the
props was found to have been completely burned,
although on removing some dirt from around them
the buried portion was quite intact. These, of course,
were burned by the flame from the fire further in, but
nothing was noticed to justify a belief that the fire had
originated as the result of the timber; the top of the
gob was also burned, but beneath the burned portion
the material was quite cool; nevertheless, on the follow-
ing day this very place was in flames, and had to be
again sealed off. It, therefore, cannot be looked upon
as satisfactory that in collieries working the Aberdare
eeam, which is so liable to spontaneous fires, so much
timber should be left as tinder to assist in starting the
fire. Much of this timber is 15 ft. long, and if extracted
could certainly be used in other sections of the colliery.

In the incipient stage, if at all possible, the heated
material should be dug out and sent to the surface. This
has,- however, been seldom possible here. As the fire
usually occurs after a fall has taken place, it seems too
big a task to dig it out, and it is let go till the time
arrives when it is imperative that if the mine is to work
the fire must be sealed off. In almost every case this
has been done with dirt stoppings, which are far from
satisfactory, with the result that frequently the fire has
developed and eaten its way through a pillar or round a
stopping. In one instance, where a combination of dirt
and brick stoppings was used, the fire very soon camo
through a solid pillar into an engine house at a con-
siderable distance from the seat of the fire. In this case,
on account of the very thin cover, subsidences to the
surface had occurred, and thus means were provided for
feeding the fire with air. Recently, however, most of
the stoppings used for sealing off fire areas have been of
brick, with dirt backing, although in some instances a
9 in. brick wall is all that is used, but sooner or later
new stoppings have to be built, although, as the workings
got deeper, the fire is more easily confined, as there is
less air inlet from the surface through fissures.

After recent experiments at a local colliery, Mr.
Lawrie is convinced that it is not advisable immediately
to completely seal off a fire in shallow workings. In
every case where this has been done great trouble has
afterwards been caused through the fire coming through
pillars or round stoppings. At the 'Swanbank Colliery,
which was recently opened out after being sealed down
for two years, another method, was successully tried.
The main fire was known to bo near the No. 2 air shaft,
and the flames came up here. This caused the tunnel
to downcast, and the workmen were able to get down
and seal up the No. 2 dip. The No. 2 air shaft was
kept'open till the old dirt stoppings were strengthened
by brick walls, when it was gradually closed, leaving
only a small funnel open. The complete closure of the
funnel on top of the air shaft had the effect of sending
the fumes through very small fissures' between the Nos.
1 and 2 seams, .and which were only a few feet apart.
As these are being noticed, they are being built off;- the
air shaft funnel opening is being gradually closed, and
very soon the management hope to be able to completely
close it. Had the fire area been completely sealed off,
there is no doubt that the stoppings and strata between
the seams would have failed to retain the smoke and
gases.

It is the intention at one of the largest collieries not
to touch the pillars till the whole of the bord work is
worked out, when the water will be allowed to rise as the
pillars are extracted. . This is to obviate trouble with
fires, and this method of flooding will, no doubt, be
effective so long as falls can be prevented in the large
area of pillars which will be standing. Another firm has
been making enquiries with a view to obtaining a plant
for punTping inert gases into fire areas, the idea being to
flood the built-off area with such gases as CO2, S02, or
even flue gases.

A good deal could be done to prevent spontaneous
fires in this district, and no doubt much greater care will
be taken in the future than has been taken in the past.
It is frequently said that, on account of the Ipswich
district being much troubled by faults, it is impossible
to lay out the workings on a regular system in anticipa-
tion of gob fires. But Mr. Lawrie is of opinion that
much more can be done in laying out the workings in
anticipation of these fires. Although the mines are
mostly small and some very much affected by faults, a
few’ are not sufficiently cut up to preclude an attempt
at least to divide the workings into manageable districts.
Much larger pillars also could be left than has been the

former practice; indeed, this is imperative as the work-
ings get deeper. The practice of leaving the present
small pillars is simply giving every chance for the pro-
pagation of gob fires without considering the losses
sustained. If larger pillars were left there would be
less falls and consequently less fires, and if mines were
divided into districts, no matter how irregular, a fire
could be isolated so quickly and so effectively that loss
of time and coal could be reduced to a minimum.

Hydraulic stowage is not suited to this district on
account of the system of working, lack of building
material, and the "thickness of the seams mostly liable
to fires. However, if the expense could be overcome, it
may be adaptable to the longwall workings being, or
to be, tried should a tendency to fires develop. In those
collieries near the sea, or where beds of sand are
available, the cost attached to this method would be
reduced. But the scheme would be wholly impractic-
able in any of the Darling Downs collieries, where the
water would make the roads impassable in a few days.
There at present the floor .rises so quickly that the pave-
ment has to be lifted every two or three weeks, and in
some cases where there is a little water, even oftener
than this.

So far, it has not been made compulsory to report
gob fires, but Mr. Lawrie thinks the recommendation
of the recent Royal Commission in Great Britain should
be adopted in Queensland, in view of the fact that the
deeper workings likely to be undertaken will no doubt
Lead to greater dangers from gob fires which may occur;
i.e., all cases of heating should be reported to the
inspector.

THE GERMAN AND AUSTRIAN COAL
AND IRON TRADES.

We give below further extracts from German
periodicals that have reached us, showing the course of
the coal and iron trades in Germany and Austria :—

Coal Market in South Germany.

Rhine traffic has been delayed for some time, owing
to the sinking of a barge in the Bingerloch fairway, and
the consequent diversion of all craft through the Neue
Fahrwasser. This delay has affected the supply of coals
to the Upper Rhine harbours, local stocks being
exhausted, and consumers dependent on oncoming
cargoes. The scarcity of craft of light draught has
caused additional delay, and sent up freights and towage
rates to an unusual extent. In the upper reaches,
vessels are able to get as far as Strassburg, but the
section thence to Basle has been closed since the war.
Deliveries up the Main have been retarded by the Rhine
congestion and the building of a new bridge. The
shortage has had to- be made good, as far as possible, by
supplies forwarded by rail to districts where the freight
difference is not so great. Small nuts have been particu-
larly scarce, and the needs of consumers of large indus-
trial nuts could not be fully met, the deficiency being
made up with large, through-and-through, screened
slack, and briquettes from local works. The house coal
trade has not been much affected, the mild weather
having lessened the demand; and there is an abundant
supply of anthracite nuts and ovoid briquettes. Coke
supplies, however, are in arrear, and in many cases
sellers have had to refuse orders. Gas coke, on the
other hand, is plentiful, but the high price checks busi-
ness. There is an active demand for brown coal
briquettes, but supplies are not coming -flong on the
same scale. The extension of contracts for Ruhr coals
beyond March 1 has not yet been settled, owing to the
delay in deciding on the renewal of the Kohlenkontor;
and the continuance of the Saar contracts beyond
March 31 is still in abeyance. It is not anticipated that
any large quantities of Belgian coal will be thrown
upon this market, the home consumption being good,
and the surplus disposed of chiefly in Holland and
Switzerland.

Increase in German Iron Ore Prices.

The Siegerland Ironstone Association has raised the
price of ironstone for delivery up to end of June by
70 pf. per ion for raw, and 1 mk. for roasted, the basis
prices being consequently 16’30 mk. for raw and
25’50 mk. for roasted ore.

Steel Union Output for January.

The total deliveries, in weight of raw steel, during
January amounted to 285,784 tons, as compared with
264,970 tons in December and 255,016 tons the previous
January.. Of this total, 75,045 .tons were semi-manu-
factured products, 157,345 tons railway super-structural
material, and 53,394 tons sections.

Rhenish Westphalian Iron Market.

The firmness of the market is, if anything, increasing,
the requirements of neutrals- having increased owing to
their inability to obtain adequate supplies elsewhere.
Consequently, sellers could get almost any price they like
to ask, for certain goods. The home demand is also
great, especially for war material and material to replace
copper and other commandeered metals.

In the ore market, the scarcity of Siegerland orcs
continues unabated, the mines being unable to obtain
sufficient labour to-increase their output. For these
mines unskilled labour is useless for underground work,
and the lack in this respect is showing itself in the
reduced output. The situation is curious, inasmuch as
■the slag heaps at local iron works are being transported
long distances by rail, for the recovery of the contained
manganese, whereas the production of the more highly
manganiferous Siegerland ore, which would not require
so many railway wagons, cannot be raised in sufficient
quantity owing to a shortage of hands.. Prices are firm,
and the same applies to Nassau red ironstone, for which
21 to,2,3mk. are being quoted. Minette is more plenti-
ful, at,about 3 to 3’20 mk. for 30 per cent, orc,, and
3’50 mk. for 32 per cent. ore.