A Method and Apparatus for Treating the Air in Mines in Order to Control Noxious Gases.
Year: 1897

page_text: Date of Application, 26th Apr., 1397-Accepted, 29th May, 1807
COMPLETE SPECIFICATION.
A Method and Apparatus for Treating the Air in Mines in Order to
Control Noxious Gases.
We, JOHN DAVY WILLIAMS, of Albert Street, Creswick, in the Colony of
Victoria, Engineer, and LOUIS DENHAME GIBSON, of Albert Street, Creswick,
in the Colony of Victoria aforesaid, Bank Manager, do hereby declare the nature
of this invention, and in what manner the same is to be performed, to be particularly
described and ascertained in and by the following statement :-
In mines in which the ground emits foul gases it is frequently found absolutely
necessary to use special means to render the air in the mine workings pure enough
to he breathed by the miners.
The means universally adopted so far as we know, consist in putting the air in
the mine into circulation so that a large proportion of the unwholesome air is
driven out of the mine and replaced by wholesome; in some cases this is effected
by forcing into the workings large volumes of pure air, and allowing the same to
mix with the foul gases, facilities being provided for the free escape from the mine
of the said mixture. In spite of this artificial ventilation, however, a noxious
mixture is breathed, and this mixture varies in the amount of noxious gas and other
impurities it contains, according to such causes as:-(1) changes of barometic
pressure; (2) the amount and localization of the air forced in; (3) the arrange-
ments for the egress of the mixed air; and (4) the variations in exudation of gases
and the pollution of the air by dust or fine mineral particles from the workings.
It has been found that in a deep alluvial gold mine, where the necessity for coping
with foul gases generally exceeds greatly that in a quartz mine of similar size and
depth, our invention is entirely applicable, and we believe it to be applicable in
the great majority of mines wherein at present ventilation is carried on imperfectly
and with difficulty.
The difficulties in the way of securing sufficiently pure air in many deep mines
are in practice often very great. They cause undue expense, yet are not
satisfactorily overcome. By our method we (to a great extent) prevent the afore-
said mixture (within those parts of the mine in which men have to work) of noxious
gases emitted from the ground with the air of the mine; we also prevent the free
escape aforesaid of the air forced in; our method involving (1) doing away with
the usual facilities for such escape, and interposing barriers or air-locks instead-
and (2) regulating the pressure of the so locked in air within the workings till it
is high enough for the purpose desired. The principle we follow up is, that if
a sufficiently high pressure of air be artifically maintained in the workings, foul
gases and mineral dust will be very largely restrained from issuing from the earth
or strata, and so the mine air will be kept wholesome.
Where bodies of foul gas, pent up under specially high pressure at some particular
point (or otherwise insufficiently retained in the earth) are suddenly and
unexpectedly liberated, they will mix with the miue air notwithstanding our
invention, but as such mixed air will form but a small portion of the air in the
whole workings, and as we provide for effective ventilation, this will not deprive
our method of applicability in any ordinary mine, although occasionally and
temporarily it may produce inconvenience.
To explain our method further, let (for the purpose of illustration) the case be
considered in which our invention was tested, viz.; an alluvial gold mine

page_text: (considerably elevated above sea level) in which, by a Root's blower acting as an
air compressing or air propelling machine, large volumes of air are without cessation
delivered throughout the innermost mine workings, and yet, in spite of the cooling
and purifying effect thereof, the air in the said workings is found at certain times
not to be breathable, or capable of keeping a candle alight. Such a condition of 5
things was found to exist, with the barometer standing at or under 28-7 inches,
owing to the quantity of foul gases exuding from the ground. In such a mine it
has been found that the heat and the emission of foul gases increased as the
barometer fell, though they sometimes increase whilst the barometer is stationary.
In such a mine it has been found that when, by the application of our invention,
the barometer rose within the workings treated from 28.7 inches as aforesaid
to 29-2 inches, candles would keep alight and men could' resume work. For more
comfortable working a higher barometer, say 29.5 inches, was found to be producible
by our method, irrespective of external atmospheric conditions.
To carry out our method, we form a lock or locks, and thereby divide the
workings, or the mine interior, into one or more closed chambers, and we pump or
force air into said chamber or chambers continuously. The air thus introduced
into the workings is not allowed to escape from the usual mine openings, except
under special circumstances, and then only through the avenue or avenues here-
after indicated. Under the circumstances hereafter stated these avenues allow
portion of the air to escape. Thus, during the ingress and egress of workmen,
material, and the like, the lock doors are opened, and a portion of the air under
pressure will escape. These doors are not the only escape avenues provided.
When air is introduced continuously into the enclosed part of the mine, as above
described, it gradually brings the pressure of the air within said part artificially
above that pressure at which it is found that the air is (owing to the presence of
noxious gases) unwholesome, and as much above as will enable said pressure to
actually keep back the foul gases in the ground sufficiently to maintain the desired
purity of air. It might naturally be supposed that a difficulty would arise by
reason of the pressure increasing at the same rate until it eventually became
detrimentally high, and rendered sustained working difficult or unpleasant; but
this is not so, and, in ordinary cases, the pressure will not rise to any such point.
No difficulty will be experienced, we find, so long as attention is given that the
When a certain
compressed air supply is not allowed to be wastefully excessive.
pressure is reached (the amount of which cannot be stated, as it varies with the
mine and the weather), but long before reaching the point when. discomfort to
workmen would be caused, the ground or strata will be found to be absorbing so
much air as to balance the influence of the air entering, any occasional excess being
carried off by a pipe, having an automatic valve, which can be regulated to open
at any desired pressure. Our invention is thus distinctly not one under which the
air to be breathed by the miners is brought to a pressure of many atmospheres ;
nor are the walls of the chamber non-porous; hence men may work therein for
indefinitely long periods without injury. The pressure employed is not so high as
to prevent water exuding from the ground into the mine.
To carry out our method of effecting the objects stated, we shall describe the
appliances we employ, although it is not essential that apparatus be used precisely
the same, so long as the same purpose is effected by substantially similar means.
In the arrangements of parts illustrated in the accompanying drawings, Figure 1
shows a longitudinal section of a mine drive on the line 9-9, in Figure 3;
Figure 2 shows a plan from above in section on the line 10-10, in Figure 3;
Figure 3 shows a transverse section on the line 11-11, in Figure 1; Figure 4
sbows a detail of an exit air tube; Figures 5 and 6 represent a longitudinal
section and an end view, respectively, of the valve of a drainage tube; and
Figures 7 and 8 represent a longitudinal section and an end view, respectively, of
the automatic valve of an air escape tube.
An air lock is made in the drive, tunnel, or mine passage leading to the various
workings (which may terminate a considerable distance away, 1,000 yards no

page_text: being too great) by inserting partitions 12, of some suitable material, as steel
boiler plate (which is strong, and, being thin, is not generally materially affected
by the crushing action which the earth often exerts on timbering) across the said:
drive A. The said partitions have their edges 13 driven into (or let into
channels made in) the ground 14, any cracks or vents being thoroughly stopped_
with clay or the like.
Two locks 15, 16 in succession, are preferably used, usually near the foot of the
down shaft of the mine, each luck having necessary valves 28, 27, 26, and sliding,
or other suitable air-tight doors 17, 18, 19 (for ingress and egress of men and
material). There are openings in the partitions, fitted by pipes 20, 21, 22, which
pass through the said locks, and by any other usual or necessary pipes, rods, wires,
or the like desired. The said pipes are illustrated in the drawing by one (a portion
of which is shown marked 20) for the ingress of the main supply of air, which is
brought from an air compressor or blower at the surface; another pipe marked 21,
which is fitted with automatic valve 35, and acts as the special avenue aforesaid for
the egress of air; and pipe 22 (fitted with a valve as 36, or a suitable trap) for the
drainage of water from the workings; a quantity of heavy mine gas is in some cases
absorbed by the water and passes off with it. By valves 26, 27, 28, the pressure in
the locks is raised or lowered as required by traffic. The valves 26, 27, 28, are
opened or closed by connecting rods 23, 24, 25, respectively, which are actuated by
levers 37, 38, 39, respectively, secured for convenience within the lock next to the
open drive leading to the mine entrance. In the open drive the pressure may be
that of the external atmosphere, or nearly so. In the same lock are also, for
convenience of handling, arranged the levers 29, 30, 31 (and connecting rods, 32,
33, 34, respectively therefrom), for operating the doors 19, 18, and 17, respectively,
of the locks.
In carrying out our process with an apparatus as shown in the drawings, we
force in the main air supply through pipe 20 to the shut-in workings or chamber B.
When the incoming air produces sufficient pressure to keep the foul gases back
the ground will be found to be absorbing a large quantity of incoming air, the
supply of which may be reduced so as to keep the absorption at a minimum. The
valve 35 is regulated so that should an undesirable increase of pressure within B
occur, the said valve will open, and allow air to escape through pipe 21, and so
lower the pressure. In practice, some excess of pressure is generally required, to
compensate for the losses of air when the lock doors are opened, and consequently,
when the air supply is well regulated, the valve 35 will only be essential in some
cases. The inner end of pipe 21, is carried to any part of the workings desired,
and said pipe bas any desired branches (as that marked 40, Figure 4), both pipe
and branches having at intervals apertures which can be closed, as by lids 41.
Bad or heated air at the roof of any part of the workings may thus be drawn off.
Upon a signal being given from chamber B, that men therein are approaching
door 19, the operator in charge of the levers in lock 15, actuates lever 37, thereby
opening valve 26 (allowing the air pressure in luck 16 to become equal that in B),
and also operates lever 29, so opening door 19 (ailowing the men to enter lock 16).
Upon another signal being given from lock 16, valve 26, and door 19, are closed,
the lever 38 is operated, opening valve 27, and lever 30 is operated, opening door 18,
thus allowing the men to enter lock 15. Next, valve 27 and door 18 are closed,
and (by lever 39) valve 28, and (by lever 31) door 17 are opened, the men thus
reaching the uninclosed part A of the mine. To reach part B from A, similar
operations to those aforesaid are performed in reverse order. It may be pointed
out, as an example, that in an alluvial gold mine, in which this invention was tested,
an increase of half a pound in the pressure of the air in chamber B sufficed to
restrain the foul gases as and for the purposes herein before explained.
Amongst the obvious variations of detail practicable whilst still employing our
invention, are the number, form, and arrangement of the parts; thus, there may be
one lock instead of two, but the latter are obviously preferable in many cases,
especially when the tram-line 42 is double.

page_text: Having now particularly described and ascertained the nature of our said inven-
tion, and in what manner the same is to be performed, we declare that what we
claim is :-
1. In the treatment of mine air, in order to control noxious gases, the method
which consists in forcing air into an enclosed chamber or chambers formed in such
mine, so as to artificially maintain therein an increased atmospheric pressure,
whereby the aforesaid exudation of foul gases from the ground will be restrained
substantially as set forth.
2. In the treatment of mine air, in order to control noxious gases, the method
which consists in forcing air into an enclosed chamber or chambers formed in such
mine, so as to maintain therein an increased atmospheric pressure, whereby the
aforesaid exudation of foul gases from the ground will be restrained, and in
allowing portions of the air within such chamber or chambers to escape
automatically when the pressure exceeds a predetermined amount, substantially as
set forth.
3. In apparatus for treatment of mine air, in order to control noxious gases, an
air lock or locks (having doors and valves operated by suitable levers) whereby the
open part A of the mine is separated from the enclosed chamber B, in combination
with piping for the compressed air supply to chamber B, and for the escape of
compressed air therefrom through a valve as 35, which adapted to open at a
predetermined pressure, substantially as set forth.
4. The general combination and arrangement of the apparatus as a whole for
treating mine air in order to control noxious gases, substantially as and for the
purposes set forth.
Dated this 26th day of April 1897.
WHEATLEY & MACKENZIE,
40 Chancery Lane, London, W.C., Agents.