Note: Descriptions are shown in the official language in which they were submitted.
BACKGROUND OF THE PRESENT INVEN~ION
The present invention relates generally to hydraulic
mining tool apparatus and more particularly to an improved
hydraulic mining tool apparatus wherein the drill strlng,
which extends from ground surface into the mineral forma~
tion, is adapted ~o be maintained stationary durin~ the
mining operation while the mining tool, mounted to the
lower end of the drill string, is adapted to ro~ate within
the mineral formation.
In recent years, hydraulic mining tool apparatus has
been developed which permits the recovery of subterranean
mineral deposits by use of a hydraulic mining fluid.
Basically, the prior art hydraulic mining tool apparatus
is characterized by the use of a high velocity liquid
fluid being discharged directly into the subterranean
mineral deposit to dislodge minerals therefrom and form
a resultant aqueous slurry which may be pumped upward
through the mining tool to ground surface. Examples of
20 such hydraulic mining tools are disclosed in my United
States Patents 4,275,926 issued June 30, 1981 and
4,296,970 issued October 27, 1981.
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Although the prio-r art mining tool apparatus have proven
useEul in their general applications, there exists sub-
stantial deficiencies associated in their use when
utilized for the recovery of unconsolidated mineral forma-
tions in deep mining applications.
J In contrast to consolidated rnineral formations,
unconsolidated mineral formations, such as tar sands, are
stabilized primarily by the compressive forces generated
by the weight of the overburden action upon the formation,
10 with the cementation forces existing between individual
sand grains being extrememly small in magnitude. As the
subjacent portions of such tar sand mineral formations
are removed during the hydraulic mining process, the over-
burden compressive force balance within the mineral forma-
15 tion is disturbed, and due to only minimal cementation
forces existing between the individual sand grains, a
` compaction or cave-in situation may occur whereby the sur-
rounding mineral formationcatastrophically falls in and
around the drill strlng and mlning tool.
When mining in deep unconsolidated mineral formations
(i.e., greater than 300 feet below ground surface), the
possibility of such a compaction situation occuring is
increased by the frictional drag forces exerted by the
rotating mining tool and drill string within the formation.
Through prolonged duration~ these frictional drag forces
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i
disturb the fragile cementation Eorces existing between
the individual sand grains and hence, increase the com-
pressive force imbalance within the the formation. The
occurence of a compaction situation in deep mining opera-
tions causes substantial pressure to be exerted along theentire length of the drill string which simu~taneously
generates substantial torque on the mining tool during
rotation. These high tortional forces may require the
intermittent shut-down of the drilling operation o-r in
extreme instances cause a complete structural failure
or twist-off of the mining tool within the formation.
As will be recogni~ed, intermittent shut-down reduces
operating efficiency while a twist-off condition could
result in the mining tool being irretrievabley lost within
the mineral formation.
In addition to the compaction and frictional drag
force deficiencies associated in the prior art, the use
of the hydraulic mining tool apparatus in deep mining
applications additionally creates substantial problems
in the transpor~ of the mined slurry from the mineral
formation upward to ground surface. These transport prob-
lems are caused primarily due to the use of jet pump
eductor transport mechanisms within the hydraulic mining
tools, which are characteri~ed by use of a high velocity
liquid stream being discharged upward through a venturi
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oriEice. During the liquid discharge flow through the
venturi, suction is developed which serves to pull the
minecl slurry from the mineral. bed through the venturi and
upward to ground surface. With specific reference to deep
mining applications, the pressure volume and velocity
requirements necessary to raise ~he mined slurry upward
to ground surface through such jet pump eductor mechanisms,
has necessarily rendered the venturi orifice of the device
- extremely small, which has severely limited the amount
of mined material capable of being transported to ground
: surface. As is evident, the reduction of the amount of
material being transported to ground surface decreases
the overall efficiency of the mining operation. Although
- positive displacement pumps (such as a Moyno pump) have
been utilized in an attempt to remedy this situation, the
use of such positive displacement pumps has proven unsuc-
cessful due to rock particles and other debris within the
slurry becoming lodged within and obstructin~ the pump
within a short period of time.
Thus, there exist a substantial need in the art for
an improved hydraulic mining tool apparatus which minimizes
the possibility of encountering a cave in sit-lation within
the mineral bed, reduces frictional dra8 forces exerted
upon the mineral bed, and further provides a reliable
method of transporting large quantities of mined slurry
upward to ground surface from deep mineral bed formations.
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SUMMARY OF THE PRESE~lT INVEl~TION
The present invention specifically addresses and
alleviates the above referenced deficiencies associated
in the prior art by providing an improved hydraulic mining
tool which is specifically adapted for deep mining appli-
cations in unconsolidated mineral formations, such as tar
sands. More particularly,the present invention comprises
an improved hydraulic mining tool apparatus wherein the
drill string, extending from ~round surface into the
mineral deposit, is adapted to be maintainecl stationary
during the mining operaton while the mining tool~ main~
tained on the lower end of the drill string, is adapted
to be rotated within the mineral formation. In the pre-
ferred emhodiment, this result is made possible by useofa hydraulic powered rotating mechanism positioned adJa-
cent the interface oE the mining tool and drill string
which effectuates an independe-nt rotation of the mining
tool relative the drill string. The speed of rotation
rnay be controlled by hydraulic pressure applied to the
rotating mechanism and ~urther may be varied throughout
the mining operation.
By maintaining the drill string stationary within
the formation while rotating only the mining toolg the
frictional drag and tortional forces exerted on the mining
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tool are minimized thereby reducing the disturbance of
the fragile cementation forces existing within the uncon-
solidated formation and reducing the possibility of
encountering a cave-in sitatution or twist-off condition.
Further, due ~o only the mining tool rotating durin~ the
mining operation, the input power requirements during the
mining operaton are reduced thereby rendering the mining
process more economical.
To augment the beneficial results made possible by
the use of a nonrotating drill string, the present inven-
tion additionally incorporates a modified tri-cone cutting
; bit attachment which is positioned upon the lowermost end
of the mining tool. In contrast to the existin~ tri-cone
bits, the modified bit of the present invention is adapted
to mine the mineral formation and direct the formation
cuttlngs axially upward into the mining tool rather than
radially outward about the annulus of the mining tool.
By this procedure, rocks and other formation debris which
accumulate at the lower elevation of the mining cavity
are effectively crushed or pulverized by the bit prior
to entry into the jet pump eductor venturi. In addi~ion,
due to the tri-cone bit of the present invention feeding
mined material axially upward within the tool, a force-
feeding effect is provided which serves to increase the
mining recovery rate, i.e. the efficiency of the minin~
operation.
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To improve the transport efficiency of mined material
upward through the jet pump eductor mechanism, the present
; invention additionally dlscloses the use of a multiple
stage slurry transport system which comprises two or more
jet pump mechanisms arranged in a serial manner along the
length of the eductor conduit. By this serial arrangement,
the mineral slurry being transported up to ground surface
. is buffered by forces generated a~ each of the plural jet
pump mechanism whereby the velocity head within the eductor
conduit is maximized to permit the maximum amount of mined
slurry recovery during operation. As such, by use of the
present invention, recovery rate heretofore associated
during the mining to a relatively deep unconsolidated
mineral formation has been substantially reduced.
3 15
DESCRIPTION OF THE DRAWINGS
These as well as other features of the present inven-
tion will become more apparent upon reference to the
drawings wherein;
Figure 1 is a perspective view of the hydraulic mining
tool apparatus of the present invention depicted in an
actual mining process of a deep mineral formation, being
disposed within a bore hole extending from ground surface
through the overburden and into the mineral bed;
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Figure 2 is an enlarged cross sectional view of the
mining tool apparatus of the present invention depicting
the mechanism utilized for rotating the mining tool inde-
pendent of the drill string;
Figure 3 is an enlarged cross sectional view taken
about lines 3-3 of Figure 2 illustrating the annular flow
channels formed at the interface between the drill strinK
and the mining tool of the present invention;
Figure 4 is an enlarged cross sectional view of the
mining tool of the present invention illustrating the
modified tri-cone bit attachment positioned on the lower
end of the mining tool; and
Figure 5 is a perspective view of the multiple stage
slurry transport system of the present invention utilized
to aid the recovery rate of minerals from deep subterranean
deposits.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
Figure 1 depic~s a mineral deposit 10 composed of
an overburden 12 and a relatively deep mineral bed 14
(i.e., disposed at a distance greater than three or four
hundred Eeet below ground surface) being mined by the
improved hydraulic mining tool apparatus 2() of the present
invention. As is well known in the art, the mining tool
_g_
apparatus 20 is typically composed of a hydraulic mining
tool 22 and a plurality of drill sections 24 which are
connected in an axial aligned end-~o-end orientation ex-
tending from the mineral bed 14 upward to ground surface
16. A jet pump supply conduit 30j jet pump eductor conduit
32, and cutting jet supply conduit 34 extend axially within
the interior of the drill sections 24 initiating from a
heighth above ground surface 16 and terminating at the
interface 36 between the lowermost drill section 24L and
the mining tool 22.
The uppermost end of the jet pump supply conduit 30
and cutting jet supply conduit 34 are connested to suitable
piping means (not shown) which are utilized to supply a
high volume, high pressure fluid flow from ground surface
16 downward through the plural drill sections 24 and into
the mining tool 22. The high pressure fluid from the
cutting jet supply conduit 34 is discharged radially out-
ward from the mining tool to dislodge minerals from the
mlneral bed 14 and form an aqueous slurry; while the dis-
charge from the jet pump supply conduit ~0 is directedupward through a venturi orifice positioned within the
eductor conduit 32. As the liquid Ls discharged upward
through the venturi orifice, suction is developed in the
vicinity of the venturi orifice which serves to pull the
mined slurry into the eductor conduit for transport upward
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to ground surface 16. Upon transport to groun~ surface
16, the mineral slu-rry may be directed to a settling pond
(not shown) for subsequent processing by conventional
separation systems.
In contrast to the existing prior art hydraulic mining
tool apparatus, the apparatus 20 of the present invention
is specifically adapted to maintain the plural drill sec-
tions 24 stationary during the mining process while per-
mitting the mining tool 22 to rotate independantly within
the mineral formation 14. The exemplary structure utilized
for this result is illustrated in Figures 2 and 3 which
depict the interface 36 between the lowermost drill section
24L and mini.ng tool 22. As shown, the lower distal end
of the lowermost drill section 24L includes a plate-like
mounting flange 40 whicn is rigidly attached to the outer
casing 42 to seal or close the end of the drill section
24L. The jet pump supply conduit 30, eductor conduit 32, and
cutting jet supply conduit 34 extend into and termi.nate
within the interior of the mounting flange 40. The conduits
30, 32 and 34 are preferably spaced at varying radial
distances from the central a~is of the drill string 24L;
with the eductor conduit 32 being positioned co-axially,
the jet pump supply conduit 30 being spaced a short dis-
tance radially outward therefrom, and the cutting jet
supply conduit 34 being positioned at a greater radial
distance therefrom.
. -11-
37~
The uppersmot end of the mining tool 22 inclucles a
similar plate-like mounting flange 50 which is rigidly con-
nected to the outer casing 52 of the mining tool 22.
The mounting flange 50 is formed having a maximum outside
diameter less than the outside diameter of the mounting
flange 40 and is adapted to abutt the mounting flange ~0
along the annular interface 36. As best shown in ~igure
3, the upper planer surface 62 of the flange 50 which forms
the interface 36 betwen the flanges 40 and 50, includes
a pair of annular recesses or flow channels 6~ and 66 which
are radially aligned with the jet pump supplyconduit 30
and cutting jet supply conduit 34 to provide a pair of
discrete fluid flow paths across the interface 36. In
addition, a central-aperture 70 positioned co-a~ially with
the eductor conduit 32 is provided in the mo~mting ~late
50 to permit fluid flow within the eductor conduit 32 to
extend across the interface 36.
A pair of cutting jet conduit extensions or segments
72 initiate within the mounting flange 50 and are in flow
communication at their uppermost end with the recess 66
and at their lowermost end with a pair of manifolds 76~
rigidly connected to the interior cylindrical surface of
the outer casing 52 of the mining tool 22. A plurality
of apertures 78 extend from the manifolds 76 through the
outer casing 52 of the mining tool ~2, each of which are
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adapted to receive either a nozzle insert (not shown) or
- plug (not shown) to permit one or more discharge fluid
outlets from the cutting jet supply conduit 34 in the for-
mation 14. A jet pump supply conduit segment 80 is addi-
tionally mounted to the mounting flange 50 and is in flow
communication at its uppermost end with the annular recess
; 64 and vertically aligned with the lowermost end of an
eductor conduit extension 84 which extends from the central
aperture 70 downward into the interior of the mining tool
- 10 22. As shown, the lowermost end of the eductor conduit
extension 84 includes a venturi insert 86 through which
high pressure liquid from the jet pump supply conduit 30
and conduit segment 80 is discharged. The vertical posi-
tioning of the venturi 86 relative to the lowermost end
of the jet pump conduit segment 80 may be adjusted as by
way of plural annular shims 88 positioned between the
eductor conduit extension 84 and venturi insert 86.
The upper mounting flange 40 and lower mounting flange
50 are maintained in an abutted orientation along their
20 interface 36 by an annular mounting ring 100 which is
.` rigidly affixed to the mounting flange 40 as by way of
plural bolts 102. A suitable annular bearing 104 is posi-
tioned between the mounting ring 100 and flange 40 to
: maintain the lower flange 50 in axial registration with
the flange 40 wh:ile permitting rotational movement of the
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17~i~
mo~mting flange 50 relative the mounting flange 40. The
uppermost surface 62 of the mounting flange 50 is further
provided with an annular gear rack 90 which e~tends upward
into an annular recess 108 formed on the mounting flange
40. A bevel gear 110 meshes with the annular gear rack
~0 and is driven by a suitable hydraulic motor 112 rigidly
affixed to the mounting flange 40. The hydraulic motor
112 may be powered by various means, but by way oE pre-
ferred embodiment utilizes fluid flow tapped off from the
cutting jet supply conduit 34. A valve 114 is provided
upstream from the motor 112 to meter the flow and hence~
vary rotational speed of the hydraulic motor 112. By such
an arrangemen~, it will be recognized that upon rotation
of the bevel gear llO, the mounting flange 50 of the mining
tool 22 is rotated about is axis independant of the lower-
most drill section 24L.
With the structure defined, the operaLion of the
improved hydraulic mining tool apparatus 20 of the present
lnvention may be described. Re~erring to Figure 1, the
mining tool 22 and plural drill sections 24 are lowered
into a pre-existing bore hole Eormed within the mineral
formation lO such that the mining tool 22 is disposed
within the mineral bed 14 of the formation 10. ~uring
initiation of the hydraulic mining process, the plural
drill sections
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37~
24 are maintained stationary within the formation and high
presure, high volume fluid flow is simultaneously directed
from ground surface 16 downward through the jet pump supply
conduit 30 and cutting jet supply conduit 32. As the
pressure within the cutting jet supply conduit 34 rises
to a sufficiently high value, the output shaft of the
hydraulic motor 112 rotates and due to the interaction
of the bevel gear 110 with the gear rack 90, causes a cor-
responding rotation of the mounting flange 50 of the
hydraulic mining tool 22.
During this independant rotational movement of ttle
mining tool 22 relative the drill sections 24, fluid trav-
eling downward through the cutting jet cond-uit 34 enters
into the annular recess 66 formed in the mounting flange
50 and subsequently travels through the cutting jet conduit
segmen~s 72 into the plural manifolds 76 positioned on
the interior of the mining tool 22; whereby a continuous
liquid discharge is directed radially outward through the
plural apertures 78 into the mineral formation 14. Through
prolonged duration, the high velocity liquid discharge
dislodges minerals from the bed 14 and forms a resultant
aqueous slurry.
Simultaneously, the liquid flow through the jet pump
supply conduit 30 travels through the annular recess 64
2S formed in the mounting flatlge 50 and into the jet pump
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7~1~
conduit segment ~0 wherein it is directed upward through
the venturi 86 positioned on the lowermost end of the
` eductor conduit extension ~4. As the liquid is discharged
through the venturi orifice 8~, suction is developed in
the vicinity below the venturi 86 which serves to draw
the mined aqueous mineral slurry through the plural inlet
ports 120 formed through the outer casin~ S2 of the mining
tool 22 and upward into the eductor conduit extension 84.
Due to the supplemental eductor conduit 84 being maintained
in vertical registry with the eductor conduit 32 during
rotation of the mining tool 22, the aqueous mineral slurry
is free to travel upward across the interface 36 formed
between the mining tool 22 and lowermost drill sections
; 24L and through the interior of the eductor conduit 32
to ~round surface 16.
Due to the inclusion of the valve 114 at the upstream
inlet to the hydraulic motor 112, the pressure applied
to the hydraulic motor 112, may be controlled or metered
to vary the rotational speed of the mining tool 22 during
the mining operation. Whereby, after a sufficient period
. of time, a radially extending mining cavity 130 (shown
in Figure 1) is formed within the mineral bed 14. As will
be recognized, with the plural drill sections 24L remaining
stationary within the mineral formati.on 14 and o~erburden
12, frict:ional drag forces heretofore exertd by the
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formation 14 along the length of the drill sections 2~
are eliminated which substantially reduces the tendancies
of the mineral formation 14 being disturbed and falling
in and about the mining tool 22. Further, due to only
the mining tool 22 being rotated during the mining process,
the input power requirements necessary for rotating the
mining tool 22 during operation are substantially reduced.
Thus, the present invention discloses a substantial im-
provement in the art which is of particular value when
mining in deep unconsolidated subterranean formations.
To augment the beneficial results made possible by
use of the non-rotating drill string, the present invention
additionally incorporates a modified tri-cone cutting bit
attachment which is positioned upon the lowermost end of
the mining tool and adapted to provide a rock-crushing
and force-feeding function of mined slurry into the mining
tool 22. The detailed construction and operation of this
modiEied tri-cone cutting bit attachment is indicated in
~igure 4 wherein ~or purposes of illustration~ the tri-
cone cutting bit attachment 150 has been illustratedschematically. As is well known, conventional dual or
tri-cone cutting bits utiliæe either two o-r three rnembers
or cones which rotate in opposition to one another to pro-
vide a grinding or CUttiTlg effect withln the formation.
Typically, the conventional cone bits are driven by a
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il7~1~
hydraulic fluid flow and are adapted to direct the forma-
tion cuttings outward from the cutting bit and upward about
the annulus o the drill string. In contrast to the con-
ventional cutting bits, the present invention utilizes
a tri-cone cutting bit which, in effect, operates in
reverse to the conventional units, whereby the cuttings
of the formation are directed axially inward through the
interior of the cutting tool for entry into the mining
tool 22.
As depicted in Figure 4, the lowermost end of the
mining tool 22 is provided with a mounting plate 160 which
is rigidly mounted to the casing 52. A central aperture
154 is provided on the mounting plate 152 znd includes
a threaded interior. The modified tri-cone cutting bit
attachment 150 of the present invention is provided with
a mounting member 156 having a threaded shank 158 adapted
to be matingly received within the threaded aperture 154
and rigidly mount the bit 150 to the mining tool 22. A
central aperture 160 is formed through the mounting member
156 and is preferably axially aligned with the venturi
orifice 86 of the eductor conduit extension 84. The modi-
fied tri-cone bitattachment 150 of the present invention
is preferably powered by hydraulic fluid pressure tapped
off from the manifolds 76 of the cutting jet supply conduit
34 and provided with a valve 162 adapted to meter the
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pressure applied to the modified tri-cone cutting bit 150
and, hence, the rotational speed of the individual cone
cutters.
In operation, pressure applied to the modified tri.-
cone cutting bit attachment 150 causes the individual cones
(illustrated schematically) to rotate in a direction
indicated by the arrows in Figure 4, whereby the rnineral
formation is mined and directed upward through the central
aperture 160 formed in the mounting member 156. By proper
construction, the spacing between the i.ndividual cone
: cutters of the bit may be maintained at a value such that
the mined material passing through the central aperture
160 is smaller than the minimal throat dimensions of the
venturi orifice ~6 oE the eductor conduit extension 84.
As such, particulate matter traveling through the aperture
160 is insured to pass through the venturi orifice 86
without lodging therein. In addition, it will be recognized
that by use of the modified tri-cone cutting bit attachment
150, a force-feeding effect of mined material through the
bottom of the mining tool 22 is provided which in cornbi.na-
tion with the entry of slurry through the side slurry inlets
120 of the mining tool 22, insures that a maximum amount
of mined material is positioned within the interior of
the mining tool 22 for transport to ground surface 1~.
In addition to the nonrotating drill sections and
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modified tri-cone cutting bit features discussed above,
the preent inventi.on additionally incorporates an improved
slurry transport system especially adaptecl for use in deep
subterranean formation mining applications. The particu-
lar improved transport system of the present inventionis depicted in Figures 4 and 5 and comprises a multi-stage
jet pump eductor mechanism wherein the eductor conduit
is provided with plural jet pump venturi orifices 86 and
discharge nozzle 31 positioned axially along its length.
At the location of each of the plural venturi orifices
86, the jet pump supply conduit 30 includes a discharge
nozzle 31 which extends into the eductor conduit 3~ and
: is axially aligned with the respecti.ve venturi orifices 86
During operation, liquid discharge from each of the
separate noz~les 31 is directed through a respective ori-
fice 86 thereby generating suction within the eductor
conduit 32 belowthe orifices 86. 'rhus, as the mined sl.urry
travel. upward through the eductor conduit 32, i.t is con-
secutively acted upon by the plural jet pump suction streams
developed at the respective orifices 86 to buffer the
transport and insure that a sufficient velocity head is
i maintained in the eductor conduit 32 to transport all of
the slurry to ground surface. By this procedure, the
throat dimensions of the venturi orifices 86 may be main-
tained at a maximum value to insure that a maximum amount
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of mined slurry is delivered to ground surface 16 through-
out the deep mining process.
Thus, in summary, the present invention comprises
a significantly improved hydraulic mining tool which uti-
lizes a stationary drill string to reduce the amount offrictional drag and torque generated upon the apparatus
during the mining process, incorporates a m,odified tri-
cone cutting bit to provide a rock-crushing and force-
feeding effect of mined material into the mining tool,
and provides an improved m~llti-stage jet pump transport
system to insure that a maximum amount of mined slurry
is delivered to ground surface during the mi.ning operation.
Although for purposes of illustration, preferred structure
as been relited herein, those skilled in the art will
recognize that various structural modiEications may be
made without departing from the spirit of the present
invention.
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