Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
CA 02782443 2012-07-05
VACUUM TRUCK WITH PNEUMATIC TRANSFER SYSTEM
SCOPE OF THE INVENTION
The present invention relates to a collection and discharge assembly for use
with
a vacuum-type collector, and more particularly a vacuum truck pneumatic
transfer
system for the collection, transportation and subsequent discharge of a
particulate
material, and preferably spillage and/or waste material from steel making,
mining
and/or ore processing operations.
BACKGROUND OF THE INVENTION
Vacuum trucks for the collection and transport of solid waste materials are
known. Such trucks are typically provided with a material collection or waste
storage
tank which is mounted on a truck frame or chassis. A vacuum source is provided
to
draw air into the storage tank from a suction or vacuum inlet placed in
proximity to the
material to be collected. Following collection, the truck is thereafter used
to move the
collected material to either a disposal or waste recycling site, where the
collected
material is discharged.
To discharge the collected material from the storage tank, various systems
have
been proposed. In a most simplified design, the storage tank is provided with
a cleanout
door which provides access to the storage tank interior, and which may be
opened to
allow the collected material to be manually removed. In addition, various
mechanical
systems for emptying waste storage tanks have also been proposed. Such
mechanical
cleanout systems include hydraulic lift systems which are operable to tilt or
incline one
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end of the storage tank, to facilitate the gravity discharge of collected
material. In other
designs, storage tanks are provided with screw discharge augers which
mechanically
convey collected solid materials from within the storage tank interior.
While conventional vacuum truck designs have proven suitable for use in the
collection of municipal waste, litter and the like, heretofore such apparatus
have
presented various difficulties in the collection, transportation and recycling
or reuse of
spillage and/or waste mining or ore processing revert material. In particular,
revert
material produced in the mining, ore processing, steel making and other
similar
processes frequently contains a significant portion, and typically 10 to 50%,
of
particulates dust and fine powders less than 0.5 cm in diameter. The use of
conventional vacuum trucks in the collection of such revert materials
frequently results
in the loss of significant volumes of revert fines by air entrainment and
dissipation.
In particular, with conventional vacuum truck designs, fine powders and dust
becomes entrained within the air when the storage tank is emptied as a result
of the
storage tank design. In particular, as the storage tank is opened to the
atmosphere and
emptied, significant portion of such materials may become entrained and
subsequently
become air borne, escaping via the storage tank access doors, discharge auger
outlets
and the like. In addition to a loss of commercially valuable material from
recycling
process streams, the escape of entrained revert materials from conventional
vacuum
trucks may present environmental concerns, particularly where such trucks are
used in
enclosed or confined spaces, such as within underground mine operations, or
inside
steel processing or industrial facilities.
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SUMMARY OF THE INVENTION
The present invention provides for a vacuum truck for the collection,
transport
and discharge of waste and/or particulate materials, and which is provided
with a
vacuum-based collection assembly. To overcome at least some of the
difficulties
associated with conventional vacuum truck designs, preferably, the collection
assembly
is provided for suction collection and pneumatic discharge of particulate
waste or revert
material produced in steel making, mining or ore processing operations. The
truck
includes a storage or collection tank for the storage and transport of
collected waste
material and a pneumatic based discharge assembly which is configured to
assist in the
discharge and/or emptying of collected material from the storage tank, for
disposal,
reuse or recycling.
Although not essential, more preferably the discharge assembly is provided
with
a discharge conduit having an outlet which is adapted for direct coupling to
an infeed
pipe, hopper or storage silo of a recycling facility. More preferably, the
discharge
assembly is provided for the discharge and/or conveyance of collected revert
material
from the storage tank to a further processing or reprocessing facility in a
discharge flow
or stream which is substantially sealed from the atmosphere.
In another aspect, an object of the invention is to provide a vacuum truck
assembly which is adapted for the collection and transport of revert materials
produced
in mining, ore processing or metal making operations, and which is suitable
for use in
confined indoor and/or underground mine environments.
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Another object of the invention is to provide a particulate material
collection
and discharge assembly for use with a vehicle based collector tank, and which
incorporates a pneumatic-based transfer system to facilitate the removal
and/or
discharge of collected particulate material from the interior of the collector
tank.
In one aspect, the present invention provides a vacuum truck which is adapted
for the collection, transportation and subsequent discharge of waste materials
having a
substantial particulate fine powder and/or dust portion, and which is adapted
to
minimize the re-entrainment or escape of such fine waste particles into the
atmosphere
during collection and/or discharge.
Accordingly, in one aspect, the present invention resides in a vacuum truck
for
the collection, transport and discharge of a waste particulate material to be
collected, the
vacuum truck including: a materials storage tank mounted on a truck frame, a
waste
collection assembly, a waste discharge assembly, and an air pump assembly
selectively
operable to induce either a negative or positive pressure within an interior
of said
materials storage tank, the storage tank having a materials inlet and a
materials outlet,
the waste collection assembly including a vacuum inlet disposed for the vacuum
fluid
flow between the vacuum inlet and the storage tank inlet during operation of
the air
pump assembly to induce said negative pressure, whereby the vacuum conduit
communicates said vacuum fluid flow from said vacuum inlet to carry an
entrained
portion of said particulate material with said vacuum fluid flow into an
interior of said
storage tank as stored material, the waste discharge assembly including a
discharge
conduit assembly for conveying a pressurized fluid flow moving from the
storage tank
materials outlet to an assembly outlet end while the air pump assembly is
operated to
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induce said positive pressure, the discharge conduit assembly including a
discharge
conduit for receiving the pressurized fluid flow to carry said stored material
entrained
therein to said outlet.
In another aspect, the present invention resides in a particulate material
collection and discharge assembly for use with a vehicle based vacuum
collector tank
having a materials inlet and a materials outlet, the collection and discharge
assembly
including: an air pump assembly, a vacuum inlet, a vacuum conduit, a discharge
conduit
assembly including a discharge conduit extending from an inlet end to an
outlet end, the
air pump assembly being selectively operable to induce a positive pressure in
said
collector tank, the vacuum inlet being positionable for the vacuum collection
of
particulate material along the ground, the vacuum conduit providing a fluid
flow
between the vacuum inlet and the collector tank inlet while a vacuum is
applied to
induce said negative pressure in said collector tank, whereby the vacuum
conduit
communicates vacuum air flow from said vacuum inlet to carry an entrained
portion of
said particulate material therewith into the collector tank interior as stored
material, the
discharge conduit for conveying pressurized air flow moving from the materials
outlet
to the outlet end while or after the air pump assembly is operated to induce
said positive
pressure in said collector tank, the communication of said pressurized air
flow from
said materials outlet operating to carry a portion of said stored material
therewith
outwardly from said collector tank interior via the outlet end.
In a further aspect, the present invention resides in a mine revert collector
truck
assembly for the collection, transport and discharge of a mining reverts, the
assembly
including: a materials collector tank mounted on a truck frame, a reverts
collection
assembly, a reverts discharge assembly, and an air pump assembly selectively
operable
to induce negative and positive pressures within an interior of said materials
collector
tank, the collector tank having a materials inlet and a materials outlet, the
waste
collection assembly including a vacuum inlet disposed for the vacuum fluid
flow
between the vacuum inlet and the storage tank inlet during operation of the
air pump
assembly to induce said negative pressure, whereby the vacuum conduit
communicates
said vacuum fluid flow from said vacuum inlet to carry an entrained portion of
said
particulate material with said vacuum fluid flow into an interior of said
storage tank as
stored material, the waste discharge assembly including a discharge conduit
having a
discharge outlet end for providing pressurized fluid flow between the storage
tank
materials outlet and the discharge outlet end during operation of the air pump
assembly
to induce said positive pressure, whereby the discharge conduit communicates
the
pressurized fluid flow from said materials outlet to carry at least part of
said stored
material entrained with said pressurized fluid flow outwardly from said
storage tank
interior via said discharge outlet end.
In yet a further aspect, the present invention resides in a vacuum truck for
the
collection, transport and discharge of a waste particulate material to be
collected, the
vacuum truck including: a materials storage tank mounted on a truck frame, the
storage
tank extending from a forward end to a rearward end, a waste collection
assembly
having a vacuum conduit with a vacuum inlet, a waste discharge assembly, and
an air
pump assembly selectively operable to induce either a negative or positive
pressure
within an interior of said materials storage tank, the storage tank having a
materials inlet
and a materials outlet, the vacuum inlet disposed for a vacuum fluid flow
between the
vacuum inlet and the materials storage tank inlet during operation of the air
pump
assembly to induce said negative pressure, whereby the vacuum conduit
communicates
said vacuum fluid flow from said vacuum inlet to carry an entrained portion of
said
particulate material with said vacuum fluid flow into an interior of said
storage tank as
stored material, the waste discharge assembly including a discharge conduit
assembly
for conveying a pressurized fluid flow moving from the storage tank materials
outlet to
an assembly outlet end while the air pump assembly is operated to induce said
positive
pressure, the discharge conduit assembly including a discharge conduit
fluidically
communicating with said outlet end and for receiving the pressurized fluid
flow to carry
said stored material entrained therein to said outlet end, the discharge
conduit extends
from an inlet end to said outlet end, the inlet end being in fluid
communication with the
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air pump assembly, the air pump assembly being operable to effect an air flow
along
said discharge conduit from the inlet end and outwardly therefrom via the
outlet end,
the discharge conduit assembly including a discharge chute fluidically
communicating
the materials outlet and part of the discharge conduit intermediate said inlet
end and
outlet end, whereby stored material carried with said pressurized fluid flow
entering
said discharge conduit is further carried with said air flow downstream
towards said
outlet end, and wherein the storage tank further includes a cover door for
selectively
opening or closing an access opening formed in said rearward end, the
discharge chute
being mounted to said cover door for movement therewith.
BRIEF DESCRIPTION OF THE DRAWINGS
Reference may now be had to the following detailed description taken together
with accompanying drawings, in which:
Figure 1 shows a schematic side view of a vacuum truck in accordance with a
first preferred embodiment of the invention;
Figure 2 shows an enlarged partial perspective view of the rear-end of the
vacuum truck of Figure 1;
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Figures 3 and 4 show a schematic view of a float ball valve used in the
sealing
of the storage tank vacuum inlet during the pressurization and
depressurization of the
truck debris collection and storage tank in discharge and vacuum operations:
Figure 5 shows an enlarged partial perspective side view of the collection
tank
rearward end, illustrating the sealing assembly used in the securement of the
collection
tank access door;
Figure 6 shows a partial cross-sectional view of the collection tank shown in
Figure 5. taken along lines 6-6', illustrating a sealing clamp used in the
cover sealing
assembly of Figure 5;
Figure 7 shows an enlarged partial perspective rear-end view of the vacuum
truck of Figure 1, with a discharge outlet end of the truck waste discharge
assembly
fluidically coupled to a revert storage silo infeed pipe during material
discharging
operation;
Figure 8 shows a perspective view of the vacuum truck collection tank access
door and waste discharge assembly shown in Figure 1; and
Figure 9 shows a schematic side view of a vacuum truck in accordance with a
further embodiment of the invention.
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DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
Reference is made to Figure 1 which illustrates a vacuum truck 10 for use in
the
collection, transport, and subsequent discharge of particulate waste revert
material 12
produced in underground mining operations in accordance with a preferred
embodiment. As will be described, in operation the truck 10 is operable to
collect
particulate revert material 12 off of the ground 6 and store it for transport
and
subsequent discharge into a remote storage silo 8 (Figure 7) located at a
recycling or
processing facility.
The truck 10 includes a truck frame 14 mounted on front and rear sets of
ground
wheels 16a,16b, and although not essential, is most preferably powered in both
movement and vacuum operation by way of a diesel motor 18. The vacuum truck 10
is
provided with material storage or collection tank 20, a pneumatic waste
collection
assembly 22 and a pneumatic waste discharge assembly 24 mounted on the frame
14.
Figure 1 shows best the collection tank 20 as having a generally cylindrical
construction extending from a closed forward end 30 to a rearward end 32.
Although
not essential, most preferably the entire collection tank 20 is pivotally
mounted to the
frame 14 by way of rear hinge mounts 34, and at its forward end 30 by a
hydraulic lift
cylinder 36. The hydraulic lift cylinder 36 is selectively operable to raise
the forward
end 30 relative to the rearward end 32 to facilitate the discharge and
emptying of
collected revert material 12a from the tank interior 20a.
An access opening 38 is formed in the lower half of the rearward end 32 of the
collection tank 20. As shown best in Figures 2 and 5 a hinged cover 42, which
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functions as a tailgate, is pivotally movable about hinges 44a,44b,44c to
selectively
allow access to the tank interior 20a for periodic maintenance or even
emptying,
depending on the waste material 12 collected. As shown best in Figure 2, the
hinged
cover 42 is selectively movable between open and closed positions by the
operation of a
pair of hydraulic lift arms 46a,46b. The activation of the lift aims 46a,46b
allows the
cover 42 to pivot about the hinges 44a,44b,44c moving from the closed position
shown
to a raised position, to allow access into the tank interior 20a via opening
38.
Figure 2 shows best a lower discharge cut-out or outlet 50 being formed
through
a lower extent of the hinged cover 42. The hinged cover 42 is preferably
provided with
the lower cut-out or outlet 50 which is provided to allow for the discharge of
collected
revert particles 12a (Figure 7) from the tank interior 20a through the cover
42 and into
the discharge assembly 24, without requiring activation of the lift arms
46a,46b.
Optionally the hinged cover 42 may be provided with suitable reinforcing ribs,
struts, or
tubes to provide enhanced structural integrity about the cut-out 50.
Figure 1 shows best the waste collection assembly 22 and including a vacuum
air pump 60, a suction inlet hose 62, suction nozzle 64 and bag collection
housing 65.
The vacuum air pump 60 is mounted on the truck frame 14 immediately forward of
the
collection tank 20. The air pump 60 is provided in fluid communication with an
upper
region of the collection tank 20 via a vacuum hose 66. The vacuum air pump 60
is of a
conventional design and type selected such that when operated, the vacuum air
pump 60
generates a desired high negative vacuum pressure within the tank interior
20a.
Although not essential, preferably the vacuum hose 66 is provided in fluid
communication with suction nozzle formed in an upper region of the dust bag
collection
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housing 65 which in turn is provided in fluid communication with the tank
interior 20a,
via a flow passage located adjacent the forward end 30. The dust bag
collection
housing 65 is provided with one or more filter bags 70 selected to prevent the
collected
dust or fine revert particles 12a from being drawn therepast into the air pump
60.
The suction inlet hose 62 as provided in fluid communication at its
forwardmost
end with the suction nozzle 64, and at its rearward end with an inlet opening
74 formed
through the top wall of the collection tank 20. As shown best in Figure 1, the
suction
nozzle 64 is most preferably positionable adjacent to the ground 6. In one
construction,
the nozzle 64 is fixed in position ahead of the front set of ground wheels 16a
with
vacuuming performed with the truck 10 in motion. More preferably, however, the
nozzle 64 is provided at the end of a movable inlet hose 62 which permits the
physical
manipulation and/or extension of the nozzle 64 upto 50' or more away from the
truck
during vacuuming operations. In an alternate construction the inlet hose 62
may
include one or more detachable hose extensions which allow for the suction
nozzle 64
to be used and/or manually moved over a variety of distances from the storage
tank 20,
to reach remote locations.
It is to be appreciated that the suction nozzle 64 and inlet hose 62 are
configured
so that on operation of the vacuum air pump 60 to impart a negative pressure
within the
tank interior 20a, air is drawn inwardly through the suction nozzle 64 with a
sufficient
velocity to effect the entrainment and lifting of the particulate material 12.
In this
manner, the suction nozzle 64 may be manually moved over the particulate
materials in
the manner of a workshop vacuum. The collected revert material 12 is carried
along the
suction hose 62 and through the inlet opening 74 into the storage tank 20. On
entering
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the tank interior 20a, the airflow velocity decreases allowing the collected
particulate
material 12a to collect along the tank bottom. It is to be appreciated that if
desired, the
collection tank 20 could also be provided with internal baffling and/or
cyclone
structures (not shown) to facilitate the settling of collected fine particles
12a within the
tank interior 20a.
Figures 3 and 4 show best a float ball assembly 76 as being secured along the
top wall of the collection tank 20 over the inlet opening 74. The float ball
assembly 76
includes as a valve seat, a steel ring plate 78 which extends
circumferentially about an
air passage leading through opening 74, a float ball 82 and a retention cage
84. The
ring plate 78 is used to mount a resiliently compressible rubber gasket 80.
The float
ball 82 is secured for selective movement within the ball cage 84 between a
lowered
position shown in Figure 4 and a raised position shown in Figure 3by a chain
86 or
other connecting cord. The chain 86 is used to manually raise and connect the
float ball
82 to the tank sidewall. The chain 86 has a length selected to allow the ball
82 to be
manually drawn upwardly and secured in position against the gasket 80 during
tank
pressurization. In the normal course, the chain 86 is used to suspend the ball
82 in the
position shown in Figure 4 when the vacuum air pump 60 is activated to place
the tank
interior 20a under a negative pressure. In such a lowered position, the ball
82 is spaced
from the rubber gasket 80 to permit air and particle flow to move from the
suction inlet
hose 62 through the inlet opening 74 and into the collection tank interior
20a.
Once the vacuum air pump 60 is turned off, the chain 86 may be used to
manually raise the ball 82 to the raised position, until the float ball 82 is
moved
upwardly into sealing contact with the rubber gasket 80, preventing the return
flow of
11
air from the tank interior 20a outwardly via the tank inlet opening 74.
Optionally, a
spring (not shown) may be used to ensure the float ball 82 to assist in its
guiding
movement between raised and lowered positions.
It is to be appreciated the float ball assembly 76 advantageously also
operates in
conjunction with the pneumatic discharge assembly 24, to assist in the
pressurization of
the tank interior 20a to a positive pressure, facilitating the discharge of
collected reverts
12a therefrom.
Although not essential, most preferably a fluid sealing assembly is provided
to
maintain a substantially fluid impervious seal between the cover 42 when
closed, and
the adjacent rearward end 32 of the storage tank 20. Figures 5 and 6 show best
the
sealing assembly as including compressible gasket seal 92 and number of
cooperating
releasable hooks 94 spaced along the lower edges of the cover 42. The gasket
seal 92
(Figure 6) is formed as a compressible elastomeric strip which extends about
the entire
peripheral edge of the end cover 42. Each of the hooks 94 act in conjunction
with the
cross head of 98 of a mechanical fastening dowel or rod 96 which engages a
respective
hook 94. In the normal operation of the vacuum truck 10, fasteners 96 are
provided in a
position engaging adjacent pairs of hooks 94 to mechanically secure the cover
42 in a
closed position over the access opening 38.
Figures 7 and 8 show best the pneumatic discharge assembly 24 used in the
discharge of collected revert particles 12a from the tank interior 20a. The
discharge
assembly 24 includes an enclosed reverts discharge chute 110, and a
pressurizing
manifold assembly 130 which are primarily carried by the end cover 42. The
discharge
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chute 110 is secured to the end cover 42 in a substantially sealing position
over the cut-
out aperture 50. The chute 110 includes a rearwardly sloped hopper box 112
which is
fluidically coupled at an outermost end to outlet pipe 114. The outlet pipe
114 is
preferably formed as a 4 to 6 inch diameter round pipe which, when the end
cover 42 is
closed, slopes marginally in a downward orientation away from the hopper box
112.
The manifold assembly 130 is used both in the pressurization of the storage
tank
interior 20a as well as the pneumatic conveyance of collected revert particles
12a as
they are discharged therefrom. The manifold assembly 130 is shown best in
Figure 8 as
including a generally horizontally arranged pressurizing discharge pipe 132, a
pressure
diverter pipe 134 and a shut-off valve 136. The pressurizing discharge pipe
132 extends
as a 4 to 6 inch diameter pipe from an air flow inlet end 140 to a discharge
outlet end
142. Most preferably an outlet valve 148 is provided adjacent to the outlet
end 142, and
which is actuable between open and closed positions to selectively permit or
prevent air
and/or particulate flow therepast and outwardly from the outlet end 142.
Preferably, the
discharge pipe 132 is mounted in a generally horizontal orientation or is
inclined in a
slightly downward inclined orientation, so as to slope at an inclined angle of
upto 100
towards the outlet end 142. Although not essential, preferably each end
140,142 is
provided with associated quick release camlock coupling 144a,144b. As will be
described, the coupling 144a is provided for rapid fluidieally connecting the
inlet end
140 to a pressurizing air source or pump 150 (Figure 7). The pressurizing air
pump 150
may be mounted on the truck frame 14, with the vacuum truck 10 operating a
single
integral unit. In an alternate construction, the pressurizing air source 150
may be
provided as a stand alone pump or pressurizing air source located at a revert
storage
and/or discharge facility. Coupling 144b is most preferably configured to
enable the
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rapid fluidic coupling of the outlet end 142 of the discharge pipe 132
directly of a
tubular feed connector or hopper fitting (shown in phantom as 152) of the
storage silo 8
during discharge of the collected revert particles 12a from the storage tank
20.
Figure 8 shows best both the outlet pipe 114 and pressure diverter pipe 134 as
being fluidically coupled to the pressurizing discharge pipe 132 between the
inlet and
outlet ends 140,142. The pressure diverter pipe 134 includes a rigid diameter
lower
section 160 and a flexible section 162 which are provided in selective fluid
communication and separated by the shut-off valve 136. The flexible upper
section 162
is connected at its upper end with an air inlet opening 164 (Figure 7) formed
at a top
portion of the storage tank 20. It is to be appreciated that the use of a
flexible upper
section 162 advantageously enables end cover 42 to be pivoted freely about the
hinges
44a,44b,44c when access to the tank interior 20a is required. The fixed
section 160 of
the diverter pipe 134 is mounted to and extends vertically upwardly from the
discharge
pipe 132 at a position spaced towards the inlet end 140 a distance of between
about 4 to
16 inches upstream from the pipe 114. Fixed section 160 preferably has a
vertical
height selected not to substantially interfere with the pivotal movement of
the end cover
42 to a fully open orientation.
Optionally, as shown in Figure 8 the fixed section 160 may further include
pressure release pipe 166, and regulator pressure relief valve 168. The
release pipe 166
and valve 168 allow for depression of the tank interior 20a, with pressure
relief valve
preventing overpressure conditions which could result in possible damage to
the truck
and/or operator injury. In a most preferred mode of operation, the pressure
relief
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valve automatically allows for the release of pressure should internal tank
pressure
exceed 15 psi.
In use of the truck 10, following each discharge of the collected particulate
material 12a, the regulator valves 168 are selectively actuated to equalize
air pressure
within the storage tank 20. Following equalization, the valves 168 are again
closed and
the float ball 82 lowered to allow the tank 20 to be evacuated.
In use of the truck 10, following collection of the reverts 12 using the waste
collection assembly 22 in a conventional manner, the truck 10 is moved to
transport the
collected waste material 12a to silo 8 at a recycling facility. At the
recycling facility the
float ball 82 is raised into sealing contact with the valve seal 80. The
outlet end 142 of
the pressurizing discharge pipe 132 is coupled to the storage silo feed
connector 152
(shown in phantom in Figure 7) via coupling 144b. Concurrently, the
pressurizing air
pump 150 is fluidically coupled to the inlet end 140 of the pressurizing
discharge pipe
132 via coupling 144a. With the air pump 150 connected, the outlet valve 148
is closed
and the shut-off valve 136 is moved to an open position to allow airflow
between the
fixed section 160 and flexible section 162 of the pressure diverter pipe 134.
The
regulator and pressure release valves 168 are further closed, and the
pressurizing air
source 150 is actuated to induce a positive airflow into an along the
discharge pipe 132
in a downstream direction of arrow 300. Initially as the air pressure pump 150
is
activated, the outlet valve 148 is maintained in a closed position for air
flow into the
tank interior 20a, via diverter pipe 134 for a sufficient time to pressurize
the tank
interior 20a to reach a preselected positive pressure. In particular, with the
outlet valve
148 closed, the airflow initially moves from the inlet end 140 upwardly
through the
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diverter pipe 134 and into the tank interior 20a via the fixed and flexible
hose sections
160,162. Preferably, the storage tank interior 20a is initially pre-
pressurized to a
minimum positive pressure, selected at between about 10 and 14 psi and more
preferably about 13 and 14.5 psi.
Following initial pressurization of the tank interior 20a, the outlet valve
148 is
opened. With the opening of the outlet valve 148, collected revert material
12a stored
within the tank interior 20a moves both under gravity and as entrained
particles together
with a released primary pressurized airflow through the chute 110, discharging
in the
direction of arrow 200. As the revert particles 12a move from the tank
interior 20a they
pass through the discharge chute 110 and into the discharge pipe 132 via the
outlet pipe
114. As the entrained revert particles 12a enter the discharge pipe 132, the
secondary
air flow 300 which moves directly along the discharge pipe 132 from the air
source 150
and outwardly from the outlet end 142 further acts to entrain and move the
collected
revert particles 12a towards and from the outlet end 142, into the silo 8 via
the fitting
152.
Most preferably the pressurizing air source 150 is operated to maintain an air
flow along the pressurizing discharge pipe at a rate of between about 800 and
1000
=
cubic feet per minute, and more preferably about 950 cu-ft/min.
As heavier entrained revert material 12a enters the discharge pipe 132
downstream from the diverter pipe 134, air pressure increases in the discharge
pipe 132
upstream from the outlet pipe 114. The pressure differential created results
in air
continuing to divert via pipe 134 into the tank interior 20a, maintaining its
positive
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pressure and assisting in the forced movement of collected revert particles
12a
outwardly therefrom through the outlet 50. In this manner, as the tank 20 is
pressurized
to a positive pressure, the discharge chute 110 is operable to permit one-way
entrained
particle flow in the direction of arrow 200 (Figure 7) from the tank interior
20a via cut-
out aperture 50, hopper box 112, outlet pipe 114 and into the discharge pipe
132. The
revert particles moving into the discharge pipe 132 then travel in the
direction of arrow
300 towards and outwardly via the discharge outlet end 142, moving via feed
connector
152 (Figure 7) into the storage silo 8.
Upon emptying of the storage tank 20, the pressurizing air source 150 is
deactivated and uncoupled. The regulator valves 168 are again opened to
depressurize
the tank interior 20a, and the shut-off valve 136 and outlet valve 148 are
closed,
returning the truck 10 to a vacuum collection ready operation.
Although not essential, in another mode of operation to facilitate the
emptying
of the storage tank 20, the hydraulic lift cylinder 36 may be activated to
raise the
forward end 34 of the tank 20 relative to the rearward end 36. It is to be
appreciated
that as the retention chain 86 is used to maintain the float ball 82 within
the ball cage 84
raised against the gasket 80, air is normally prevented from flowing outwardly
along the
vacuum inlet hose 66, allowing the storage tank interior 20a to be readily
pressurized to
a selected positive pressure by the air source 150. The higher gas pressure in
the tank
interior 20a facilitates the flow of collected reverts 12a from the tank
interior outwardly
through the cut-out aperture 50, through the discharge chute 110 and into the
silo 8 via
the discharge pipe 132. As the collected revert particles 12a are thus
discharged from
the discharge pipe 132 directly into the revert silo 8, the truck 10 permits
the movement
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of collected reverts 12a from the tank interior 20a directly into the silo 8,
whilst
minimizing atmospheric entrainment of the collected material.
It is to be appreciated that the manifold assembly 130 may be provided with
suitable shutoff valves 120, as well as optionally pressure relief valves (not
shown) to
allow the storage tank 20 to be safely pressurized. Suitable pressure gauges
are
preferably also provided to allow for the monitoring of the positive pressure
in the
system.
Although Figure 1 illustrates the vacuum truck as including a hydraulic lift
cylinder 36 for use in assisting the emptying of the collector tank 20, the
invention is
not so limited. It is to be appreciated that the storage tank 20 could be
fixed to the
frame 14 against movement. In a further alternate construction, reference may
be had
to Figure 9 which illustrates another embodiment of the invention, in which
like
numerals are used to identify like components. In Figure 9, the vacuum truck
10 is
provided with a mechanical screw auger 180 which is mounted for rotation
within the
collector tank interior 20a. The screw auger 180 is selectively operable to
mechanically
displace any collected reverts 12a towards the cut-out aperture 50, and
therethrough into
the discharge chute 110. The truck 10 may further be provided with one or more
selectively activatable vibrators 182 which operate to impart a vibratory
movement on
the collection tank 20 to facilitate tank emptying.
Although the detailed description describes the use of a diesel motor 18 to
provide power to the truck 10 and vacuum air pump 60, the invention is not
limited. It
is to be appreciated that other truck power plants could also be used
including, without
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restriction, electric or gasoline motors, hydrogen fuel cells, and/or propane
operated
combustion engines. By way of non-limiting example, it is to be appreciated
that an
electric motor or fuel cell could alternately be provided to advantageously
allow the
truck 10 to be operated for larger periods in underground and/or confined
spaces,
without concern of CO or CO2 gas contamination.
Although the detailed description describes the vacuum truck 10 as used in the
collection of mine reverts in underground applications, the vacuum truck 10 is
equally
suitable for use in the collection of a variety of different types of solid
and/or semi-solid
material in both confined and unconfined spaces including, without
restriction, other
types of waste materials such as gravel, sand, litter and the like.
While the foregoing description describes the vacuum truck 10 as including a
separate vacuum air pump 60 and pressurizing air pump 150, the invention is
not so
limited. In an alternate construction, the truck 10 could be provided with a
single air
pump which is either reversible, or provided with appropriate switchable-
valving which
operates to induce both positive and negative pressures within the tank
interior 20a
during waste discharge and collection operations.
While the detailed descriptions describes and illustrates various preferred
embodiments, the invention is not to the specific preferred constructions
which are
shown. Many modifications and variations will now be apparent to persons
skilled in
the art. For definition of the invention, reference may be had to the appended
claims.
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