Note: Descriptions are shown in the official language in which they were submitted.
B~R~OUND OF ~HE ~ ION
Fi~ld of the Invention
This invention i8 in ~he field of conveying solids
in a batch type process wherein said solids are delivered
through ~ slide ~al~e, and t:hen dr~pped through an opening
in a blow tank, whereupon ~ley are vibrated and diacharged
into a pressurized airstream.
Descxiption of the Prior Art
In the mining of ooal or metals, there are sub-
sta~tial environmental and saety hazards which relate to
the disposa~ of the waste material produ~ed during under
ground mining. ~he problem is particularly severe where
the was~e material is a hard rock ~uch as the high densi~y
quartæ which is a by,product of gold mining. Lifting the
rock to the ~urface for disposal involves great expense,
particularly since some gold mine6 are many thousands of
~eet below the surface of ~he earth. Even if ~he rock is
lifted to the sur~ace, ik must then be stored somewhere
and thiR o~ten creates an e~vironmental pxoblem. ~urther-
more, deep mines become ~uite hot, and the areas where
~he roGk has been removed must be ventilated and cooled,
considerably increasing *he cos~ of ~he mining operation.
Orle o:~ the most serious hazards in mining is known
a~ "rock burst"O As the depth of the mine increases, the
pressure increaees and the stresses on the rock at the sides
and in the roof of ~:he mined out areas al~o increase. When
the ~tre~s reaches the limit whit::h the roc}c can s~and, it
,. ~
: '
~imply explode~ e~r bur~ts.
A8 ~oon as ~rl area is min~d, compxession of the
~ide walls and a ~agging of the roof begin, creating a
condition known as n closure " . As t.he amount o:E ~losure
increases 7 rock ~re~s increases . Blowing was te rock in
at very high ~relc cities and pac:king in this material up to
the roof before c:losure becclmes appreciable causes the packed
material ~o compre~s with su}: s~quent closure and gradually
carry the load of the unsupported material. Filling the
mined out areas pneum~tically will pack the fill material
to densities approaching 80~ of the original rock density,
thereby reducing c:losure to about 20~ With other types of
supports, such as timber pac:ks and the like, closure is as
high as 75~
The most desirable solution is thus to extract
the ore and move the waste rock around underground to
areas which have been previous ly mined . This e l; m; n~tes
the expense and ~he problems associa~ed with bringing the
rock to the suxface. It also reduces the volume o~ the mine
which has to be ventilated and cooled/ and further has the
additional }:enefi~ of decreasing the length of mine cavities
which have to be shored up wi th timbers ~o prevent collapse,
a time consuming and expensive procedure.
Co~nercial . -chinery for moving rock around in
a mine normally utilize& a rotary fe~3ding arld metering
apparatus which operates continlaously. The was~e rock is
metered in o a pipe and is blown to a remo~e lucation where
it is piled into ~o~called "~topes n which are exca~ations
resulting from the removal of ore.
1l
The difficulty with rotary feeders in ~his
environment is that they havle a very short service life
and are impractical. ~igh density quartz rock, for example,
is very abrasive. Since the vanes on rotary feeders are
continuously rotating, the rate of wear is greatly accele-
rated. In order to reduce wear, rotary feeders are often
operated with air pressures in the conveying pipes of
ahout 5 to 6 psig. This pressurized air is introduced
on the upstream side of the rotary feeders to carry the
rock alona the pipe for conveyance to a remote location
for backfilling a stope. Lower air pressures are used to
minimize damace to rotary air locks and lower pressures
require larger diameter pipes, which are more costly and
difficult to handle to convey the same amount of material
The followinc U.S. paten~s are of general interest
in connection with the handling of solid residues by means
of fluid 6treams.
Adams et al U.S. Patent No. 1,347,358 describes a
lifting apparatus for solids makinc use of a closed receiver
and a plurality of air pipes which act on the material to
loosen and break up the mass to such an extent that it will
enter into the lower open end of a discharge pipe.
Bucky U.SO Patent No. 2,536,869 involves first
breaking the ground by a modified shrinkage method of stoping,
and then introducing waste fill at the top of the stope as
the fragmented ore is withdrawn from the bottom and as its
upper surfaLce subsides within the stope.
In U.5. Patent No. 3,~S3,B65 to Kanics there i5
a~¢ribed ~ pneumatic: conveyor pipe line or ~onveying bulk
material utilizing passageway~ whi ::h corlnect the ~as duct
to the bulk material duct ~I.oughout the length of ~,the
conveyor pipe line.
V. S . Patent No. 3, 268, 264 to Squires also deals
with a pneumatic c:onveyor in which the ~olid flows through
the conveyor in a dense state reseI~ling a liquid-lilce
i~ low .
Brown ~3.S. Patent NoO 3,268,266 is also directed
to a pneumatic conveyor system utilizing a rotary feeder.
The vane~ s~f the eeder are provided with wipers at their
extremities. The hu~ o~ the rotor is provided with caps
which have fingers entering into the ~paces between the
vanes and which carry annular ribs which are radially spaced
to provide a se2~1 between the rotor arld a lining o synthetic
resin which faces the end w~116 of the chamber.
Andy U~ S, Patent No. 3, 478, 520 addreeses itself
to a method of filling mine cavities by means of a filler
materlal ~uch as an expandable plastic. The expandable
material is placed in the abandoned mine cavity, and suffi-
s::ient he~t i5 applied to cause the material to expand and
completely fill the cavities to thereby reinforce the
gxourld above it.
Freeman, Jr. et al U.Sc Patent No. 3~480~331
descrlbes a fluidizing conveyor apparatus including a gate
valve fox metering the ~low of fluidi~ed material aïong
the conv~yor. The gate valve ha~ a blade whi~h moves
vextically to ad~ust ~he size of the passage through which
tha ~luidized ~aterial fl~wso
Velegol U.S. Patent Mo. 3,~02,551 deal6 with an
un~erground fluid ~or,veyor t:ran~portation sy~tem particularly
designed for removing fines ,~nd the like from coal mining
installations.
Schumacher et al U.S. Patent No. 3,656,661
describ~s a mea~uring device for a penumatically operated
system in~luding a compar~mentali2ed dosage disk which has
a discharge side leading to an air duc~ wi~h an ejector
unit mounted therein. This side is sealed by a flexible
lip seal and the reverse side is sealed by a ga~ket. The
di~charge side of the dosage disk is an area of low pressure
so that the granular material is drawn into the conveyor
ct.
Rusterholz.U.S. PatQnt No. 3~871,711 describes
a method for pneumatically conveying solid materials by
means of gas jets located along a conveying pipeline.
Valves are provided for synchxonizing the ga~ jets with the
clo~ing of each pipeline section to cause an ~ntermittent
movement of the ~iscret~ solid material along the pipeline.
In Korn et al UOS. Patent No. 3,937,522 there
i~ described an appaxatus for continuously feeding gra~ular
material to a conveyor pipeline which includes a vertical
cylindrical ch~mber with mean~ in the chamber at different
levels which act to alternately lift and release successiv~
portions o:E the material, thereby preventing grains from
interlocking and forming lumpsO
3L~$~,~
~ n Ru~ter~lz IJ~Sa P3~ten~ No. 3,955,853 there is
dLisclosed a ~y~tem or the pneumatic con~yance of ~olid
ma~t~3rial~ by pneumatic pul~e waves without ~he nec:e6sity
of presæurizing the container.
Finally, in Waymerlt l~.S, Patant NoO 4~059~963
there is described a method of backfilling a mir~e by
dewatering a ~lurry ~o that it ean be u~ed more conveniently
as a baeJcfill either alone or in combination with cement
to provide a mortar~
~UM~RY 0~ T~F. lNV ~:N'l'ION
The present invention provides an apparatus ~or
conveying abrasive solids to a backfilling locatioll utilizing
a blow-pot type loadex, and means for deli srering solids ~o
the loader. A vibratory ~eeder receives the ~ischaxge from
the loader and delivers the same to a pressurized conduit at
a very accurately controllable xate e~f delivery. The present
invention employs a reciprocahle slide valve which is disposed
between the delivery means ar~d the loader I ~he slide valve
when closed prc~vidiIIg a substantially air-tight closure for
the loader. The loader as well as the conduit may be
pre3surized c
In a pr~erred ~orm of the inventior~, the loader
has a generally conical disch~rge end and a vi}: ratory
f~eder is located in ~::lose proximity to ~he discharge end.
The ~ibratory feeder is preîerably loca~ed in a pre~;surized
housing of its own.
The pre.~ent ir~vention also provides a method for
s~onveying abrasive 601ids wherein 5UC~ ;olids are delivered
through a slide valve and into a blo~ kank, the solids are
vibrated while they are being discharged from the blow tank
into a conduit, and then conveyed by means of pressurized
air to the backfill location. In a preferred form of the
invention, the air is in~roduced into the conduit in suffi-
cient amounts to form a suspension containing about 3% to 10
bv volume solids. One of the features of the invention is
that higher pressures can be used in conveying, the pressures
in the conduit being at least 10 psig.
BRIEF DESCRIPTION OF THE DP~WINGS
A further description of the present invention will
be made in conjunction with the attached sheets of drawings,
in which.
~ IG. 1 is a view partly in elevation and partly
in cross section illustrating a conveyor assembly according
to the present invention;
FIG. 2 is a cross-sectional view taken substantially
along the line II-II;
FIG. 3 is a plan view of the slide valve; and
FIG. 4 is a fragmentary cross-sectional view of
the slide valve assembly used in accordance with the present
invention.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
In FIG. 1, reference numeral 10 indica~es generally
a support structure including a plurality of legs 11 and 12
for positioning a dispensing device relative to a pressurized
conduit 13. A rock material in the form of granules or the
--8--
like is delivered by means of a conveyor (not shown) to a
hopper 14 whieh is securely mounted to a pair of opposed
channel beams 15 and 16. The bottom for the hopper is
provided by a reciprocable slide valve 17. As best seen
in FIGS. 2 and 4, the slide valve 17 is arranged to slide
between opposite sets of plates 18 and 19~ A hydraulic
cylinder 2~ has a piston 21 mounted for reciprocation
therein, the piston 21 carrying an actuating rod 22 which
is connected to the slide valve 17 by means of a connector 23
as shown in ~IG. 3. The other end of the cylinder 20 i5
fixedly secured to the frame by means of a connection 24.
The actuator or the slide valve 17, including the hydxaulic
cylinder 20 and its operative parts are supported by means
of supexstructure 25.
The slide valve 17 also forms an air-tight closure
for a blow-pot feeder generally indicated at reference
numeral 26. The blow-pot feeder 26 has a flange 27 which
is also arranged to be secured to the superstructure 25.
The blow~pot feeder 26 has a generally conical
bottom 28 which discharges into a vibrating tray Z9 of a
vibrating type feeder such as the commercially available
"Syntron" feeders. The feeder is actuated by a motor 30
which is enclosed in its own pressurized housing 32.
A spring 31 serves to isolate ~he motor 30 from the housing 32.
shaft 33 transmits high requency, low amplitude pulsations
from the mol:or 30 to the vibrating tray 29. The tray 29
is likewise isolated mechanically from i~s support by
means o a spring 34 extending between the tray 29 and the
conduit 13. It will also be noted that the forward edge 29a
of the tray 29 extends beyond the intersection of the tray
wi~h ~he angle of repose identified at reference numeral 35.
The ma~erial falling through the feeder will not be entrained
in the airstream in the conduit 13 until the vibrating feeder
is started.
Pressuri~ed air is applied into the conduit by
means of a blower 36. The same blower may supply air under
pressure to the blow-pot feeder 26 by means of an inlet
line 37.
~ he blower 36 provides air in sufficient volume
to form a suspension containing about 3% to 10% by volume
solids. The suspension is conveyed through the conduit 13
at a pressure of at least 10 psig, and typically about 11
to 12 psig. This permits a smaller diameter conduit 13 to
be used, the typical conduit being about 8 inches in
diameter. At an air velocity in the conduit of about 120
to 150 ft/sec, the equipment can convey about 30 to 50 tons
per hour. The conduit is shown discharging into a heap 38
which is backfilling a mined out axea.
The sequence of operation of the assembly is as
follows~ The blower 36 is started with no air passing
through conduit 13 and the slide valve 17 is opened. rrhe
blow-pot 26 is filled, and the slide valve 17 is closed.
The filling of ~he blow~pot is controlled either by weighing
the flow on the conveyor belt or by running the belt for a
specific time. After slide valve 17 closes, suitable valves
(not shown) are opened so that the airflow passes into the
conveying conduit 13. The vibrating pan feeder motor 30
i5 started zmd i8 run until the blow-pot 26 is empty. The
-10
~p~
vibrati~y feeder i~ then ~hu~ off an~ the system is ready
~or anoth~r ~y~le.
In a~cordance wi~h Wle present invention, thP
expensive rotary air lock previously used in such ~ystems
ha~ been eliminated and replaced with a simple and inexpensive
slida valve. Such valYes operate only once per cycle which
usually means ~bout once every 3 or 4 minutes. Such slide
Valvas, ~herefore, do not ex]p2rience the wear of rotary air
locks whi~h are operating con~inuously.
The slide valve operates only when the air has
been cuk off fxom the 3ys~eml and ~his also reduces wear.
In contrast, rotary air locks operate continuously at full
s~stem operating pressure. Furthermore, the wearing
surfaces on the slide valve are flat plates or strips which
are inexp~nsive and are easy to replace. Air leakage
through he slide va~ve of this system i5 also substantially
l~ss than leakage through a rotary feeder. Power require-
ments for the feeder are quite small.
I~ should be evidant that various modifications
can be made t~ the described embodiments without daparting
from the scope of the present invention.
