Note: Descriptions are shown in the official language in which they were submitted.
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This invention relates to a dust collection system, and
primarily to a system for collecting dust which is generated in
rock drilling.
During mining and large construction projects, it is fre-
quently necessary to drill into hard rock. Such drilling creates a
considerable amount of dust. This is particularly so when the
drilling is done in a quarry or in a large excavation. A large
number of drills are used, and the dust which is generated creates
a serious health hazard for the workers on the project.
A number of solutions hav0 been proposed in an effort to
contain this dust. Generally, the means by which this is done is
that a hood is placed around the drill rod to collect the dust
generated at the drill. A venturi operating with compressed air
is used to suck air in and around the hood to pick up the dust and
rock particles and convey them to a cyclone separator. Apparatus
which is now in use employs a cyclone separator to separate out the
heavy cuttings from the dust, and the dust rises to the top of the
separator where it is collected in cloth screens or bags.
Equipment which is now available has proven to be not
too successful in the field. The main problem is that in drilling,
water is frequently encountered at the drill rod and when this
water finds its way into the cyclone separator, the dust which
rises within the separator is moist, and this can immediately clog
up the cloth screens. Thus, although the dust collectors which
are now available work extremely well under favourable conditions,
on the job they can clog up within a matter of a few minutes.
Once the cloth screens are wet, the unit must be completely dis-
mantled and the cloth screens replaced with dry clean screens.
Thus, during a normal shift, the separator may only work for one
or two hours. The balance of the time, the equipment is shut down
for repairs and cleaning.
The separator of the present invention overcomes this
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problem and is able to operate even when there is a considerable
amount of water and moisture in the cuttings.
The primary object of the present invention is to provide
a dust collecting system for use in connection with hard rock dril-
ling in which rock cuttings and dust are separated and delivered to
containers and in which only a small percentage of dust is permit-
ted to escape to atmosphere.
A further object of the invention is to provide for the
application of clean air at various stages in the separation of
rock cuttings and dust in order that the wire and cloth screens,
used in the system are kept clear of cuttings and dust for more
effective separation of the cuttings and dust,
A further object of the invention is to provide means
whereby an effective flow of air at a sufficiently high pressure
is maintained throughout the various stages of the system to ensure
progressive separation and extraction of: first, heavy rock cut-
tings, second, light rock cuttings and dust, and third, dust only.
These and other objects of the invention will be apparent
from the following detailed specification and the accompanying
drawings in which:
Figure 1 is a schematic illustration of the apparatus em-
ployed in carrying out the invention,
Figure 2 is an enlarged partial sectional view of the
final stage of the apparatus shown in Figure 1.
Figure 3 is a section through the first air supply pipe
delivering pressure air for cleaning dust from the separator screens,
showing the air supply openings above screen level.
Figure 4 is an enlarged detail of the openings in the dust
collector conduit.
Figure 5 is a horizontal section taken on the line 5-5 of
Figure 4,
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Referring to the drawings, Figure 1 is a schematic illus-
tration of the invention which includes the drill rod 10 project-
ing into the rock 11 and operated by percussion from a drilling
machine, not shown, and surrounded by a hood 12. The hood 12 has
a head 13 to which one end of a flexible pipe 14 is connected, the
other end of the pipe being connected to the inlet end 15 of a
first stage separator 16. Inserted in the pipe 14 is a venturi 17
to which an air inlet connection 18 is inserted, the air inlet 18
being so positioned in the venturi 17 as to direct a stream of air
downstream through the restricted portion 17a of the venturi to-
wards the first stage separator 16.
The first stage separator 16 is preferably a cylindrical
vessel disposed horizontally and has a heavy rock cuttings dis-
charge outlet 19 and a light rock cuttings and dust discharge out-
let 20 in the lower portion of the vessel. A dust only outlet 21
is located at the end of the vessel opposite from the inlet end 15.
A partial wire screen 22 located within the lower portion
of the separator 16 immediately downstream of the rock cuttings
discharge outlet 19 permits the passage through the separator of
light rock cuttings and dust, while diverting heavy rock cuttings
downwards through the discharge outlet 19.
A partial wire screen 23 located in the upper portion of
the separator 16 immediately upstream of the light rock cuttings
discharge outlet 20 diverts the light rock cuttings downwards into
the discharge outlet 20 and additional wire screens 24, located
downstream of the discharge outlet 20, permit the passage of a
large proportion of dust towards the dust only outlet 21.
Between the screens 24 and the dust outlet 21 an air in-
let valve 25, located in the wall of the separator 16, is so posi-
tioned as to direct a stream of air under pressure onto the screens24 to clean the screens of accumulated wet dust.
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The dust outlet 21 of the first stage separator 16 in-
cludes a venturi 26 and an air connection 27 is so positioned as
to direct pressure air downstream through the venturi 26,
A pair of rubber valves 28 and 29 are connected respec-
tively to the discharge outlets 19 and 20 of the first stage sepa-
rator 16, These valves 28 and 29 are of the type whose walls re-
main in close contact with each other until such time as the weight
of material passing through the outlets 19 and 20 forces the walls
apart to permit discharge of material from the separator,
A second stage separator 30 is disposed vertically and
has a tangential inlet 31 on its side wall and has a dust discharge
outlet 32 at the bottom, The dust outlet 21 of the first stage
separator 16 and the tangential inlet 31 of the second stage sepa-
rator 30 are connected together by the hose connection 33,
A series of wire screens 34 extend between the side walls
30a of the second stage separator 30 at an angle to the horizontal
above the tangential inlet 31, with the lower screen 34a being set
at an angle downwards greater than the angle of the screens 34 in
order to divert a large portion of dust entering from the tangential
inlet 31 downwards towards the dust discharge outlet 32 and into a
dust receiving bag 35 attached to the outlet 32, A cloth screen 36
- is located above the uppermost of the wire screens 34,
The upper fine dust and air discharge outlet 37 includes
a venturi 38 and an air inlet connection 39 is so positioned in the
outlet 37 as to divert the flow of fine residual dust out through
the upper end of the discharge outlet 37 to the atmosphere, The
upper end of the discharge outlet 37 is provided with a cap 40,
Referring now to Figures 2 to 6 of the drawings, the
screens 34 and 34a are supported between annular rings 41 and an an-
nular rubber seal 42, also supported by the rings 41, has its outer
- peripheral edge making sealing contact with the inner surface of the
side walls 30a,
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An air supply pipe 43 is inserted through the top coni-
cal portion of the second stage separator 30 adjacent to the side
at which the inlet 31 enters the separator 30 and extends downwards
through the screens 34. This air supply pipe 43 is provided with
two or more air outlet apertures 44 located immediately above each
of the screens 34 and set at an angle in order to project streams
of air over a wide area of the screens 34, The lowermost end of
the air supply pipe 43 is closed.
A particle receiving conduit 45 extends downwards through
the screens 34 at a position diametrically opposite from the air
supply pipe 43 and is provided with a series of particle inlet
openings 46, one immediately above each of the screens 34. The in-
let openings 46 are cut at an angle to the vertical so that the
widest part of the openings are adjacent to the screens 34. The
lowermost end of the conduit 45 is formulated to provide a venturi
47 which is located in the lower conical portion of the second stage
separator 30.
An air supply pipe 48 is connected to the top of the con-
duit 45 and is provided with a valve 49. The air fed down through
the conduit 45 will effect a suction at each of the openings 46 to
draw air and particles from the tops of the screens 34 and down
through the conduit 45 and venturi 47 and through the lower outlet
32 of the separator. The annular seals 42 at the level of each of
the screens 34 ensures maximum suction of particles from each of
the screens through the openings 46,
In the operation of this invention, the rock cuttings,
large and small, together with dust extracted by the drill 10, en-
ter the hood 12 and are discharged through the pipe 14. The air
injected through the connection 18, combined with the venturi 17,
ensures that the drilled products will be carried at a speed suffi-
cient to ensure that none of the products will escape from under
the hood 12 to affect the operator of the drilling machine,
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As the combined heavy and light rock cuttings and dust,
often laden with water, enter the first stage separator through
the inlet 15, a part of these products particularly the heavy cut-
tings are intercepted by the screen 22 and the heavy rock cuttings
fall down through the outlet 19 and rubber valve 28 and are depo-
sited in a suitable container. Products which pass through and
above the screen 22 next pass under the screen 23 and are inter-
cepted by the screens 24. Light rock cuttings and dust clinging to
these cuttings fall down through the outlet 20 and through the rub-
ber valve 29 and are deposited also in a suitable container. Dustwhich passes through the screens 24 is carried at speed through the
venturi 26 and through the tangential inlet 31 into the lower por-
tion of the second stage separator 30 where a large portion of the
dust is intercepted by the various screens 34, which screens are
continuously cleaned by the streams of air delivered through the
apertures 44 in the air supply pipe 45, Theapertures 44 being set
at an angle cause streams of air to sweep over the whole area of
the screens 34 to carry all particle matter and dust ~hrough the
openings 46 in the conduit 45 for discharge from the separator
through the lower outlet 32, The uppermost cloth screen 36 inter-
cepts a proportion of dust which has been able to pass through the
lower screens 34 so that only a slight plume of dust escapes from
the separator 30 through the outlet 37 assisted by air injected in-
to the venturi 38 from the air inlet 39. The plume of dust ejected
at the outlet 37 is of minimum density and has little or no effect
on the environment but gives the operators an indication that the
system is working satisfactorily in extracting a maximum of undesi-
rable materials. The introduction of air at various stages through
the first and second stage separators, combined with the venturis
17 and 26, ensures a high speed flow of air under the hood 12 and
through the system, combined with the direction of air over the
faces of the various screens ensures that the screens will be kept
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free of any accumulation of dust, particularly wet dust, to the
extent that the system can be operated continuously with a minimum
of servicing.
