U.S. patent number 3,799,614 [Application Number 05/283,309] was granted by the patent office on 1974-03-26 for method and apparatus for excavating settled body of solids.
This patent grant is currently assigned to Marcona Corporation. Invention is credited to John J. Gilbert, John A. Miscovich.
United States Patent |
3,799,614 |
Miscovich , et al. |
March 26, 1974 |
METHOD AND APPARATUS FOR EXCAVATING SETTLED BODY OF SOLIDS
Abstract
Method and apparatus for excavating and removing a settled body
of discrete mineral solids (e.g., a tailings pond from a mining
operation) by procedures which progress downwardly from the surface
of the body. High pressure streams of liquid are traversed along a
path in a pulping zone lowermost in first region of the body. The
liquid forms a pumpable slurry with the mineral solids in the zone,
and the slurry is then pumped from the zone leaving an undercut
cavity sufficient to cause collapse of the overburden of solids.
The collapsed overburden is then formed into additional pumpable
slurry which is removed by pumping. Successive stages of excavation
are carried out by moving the streams of liquid downwardly to a
second region where the foregoing steps are repeated. In the
apparatus a caisson is disposed vertically in the body and
stabilized by means of a plurality of circumferentially positioned
pilings. A plurality of high velocity nozzles are mounted in the
caisson to direct liquid streams into a pulping zone surrounding
the caisson. The slurry which is formed in the pulping zone flows
through portals in the caisson into a slurry sump in the lower end
of the caisson where a pump removes the slurry through a discharge
line leading from the caisson. In one embodiment the caisson is
fixedly secured to the caisson and jets are provided to direct
liquid streams into regions below the lower ends of the caisson and
pilings to sink the apparatus downwardly to the next lower region
for additional stages of excavation. In another embodiment, the
caisson is mounted for relative vertical movement with respect to
stationary pilings.
Inventors: |
Miscovich; John A. (Orange,
CA), Gilbert; John J. (San Francisco, CA) |
Assignee: |
Marcona Corporation (San
Francisco, CA)
|
Family
ID: |
23085428 |
Appl.
No.: |
05/283,309 |
Filed: |
August 24, 1972 |
Current U.S.
Class: |
299/17; 37/195;
299/18 |
Current CPC
Class: |
E02F
3/8808 (20130101); E21C 25/60 (20130101); B65G
53/30 (20130101); E21F 13/042 (20130101); E21C
47/00 (20130101); E21C 41/00 (20130101) |
Current International
Class: |
E02F
3/88 (20060101); E21C 47/00 (20060101); E21F
13/04 (20060101); E21C 41/00 (20060101); E21F
13/00 (20060101); E21C 25/00 (20060101); E21C
25/60 (20060101); B65G 53/00 (20060101); B65G
53/30 (20060101); E21c 045/00 () |
Field of
Search: |
;299/17,18 ;302/14-16
;37/57-63,193 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Purser; Ernest R.
Claims
We claim:
1. A method for removing a settled body of discrete mineral solids
including the steps of directing a stream of liquid through at
least one nozzle substantially laterally into a first pulping zone,
the nozzle being located at a first predetermined elevation below
the upper surface of said body whereby the liquid forms a pumpable
slurry with the mineral solids in said zone, pumping the slurry
from the zone, traversing the liquid stream through a predetermined
path in said zone to form an undercut cavity in said body
sufficient to collapse the overburden of mineral solids overlying
said cavity, causing the collapsed overburden of mineral solids to
be formed into additional pumpable slurry with said liquid, pumping
the additional slurry from said zone, directing additional liquid
to a region below said nozzle to cause the same to sink downwardly
through said solids to a second predetermined elevation below said
first elevation, directing said stream of liquid into a second
pulping zone located at said second elevation, and repeating said
steps of pumping the slurry from said second zone, traversing the
liquid stream through a predetermined path in said second zone to
form an additional undercut cavity sufficient to collapse the
overburden of mineral solids thereabove, causing the collapsed
overburden to be formed into additional pumpable slurry with said
liquid, and pumping the additional slurry away from said second
zone.
2. A method as in claim 1 in which the stream of liquid is moved
successively to a plurality of regions each located at successive
elevations below said first elevation, and the mineral solids
within each region are removed by repeating in each region the
steps of directing streams of liquid into pulping zones to form a
pumpable slurry, pumping the slurry from the zones, traversing the
streams through predetermined paths in the zones to cause collapse
of overburden in the regions, causing the collapsed overburden to
be formed into additional pumpable slurry, and pumping the
additional slurry from the respective zones.
3. A method of removing a settled body of discrete mineral solids
capable of being formed into a pumpable slurry by nozzle means and
slurry pump means, including the steps of establishing the nozzle
means and slurry pump means in the body with the nozzle means
located at a first predetermined elevation below the upper surface
of said body, directing at least one stream of liquid from said
nozzle means into a path extending substantially laterally
therefrom to define a pulping zone whereby the liquid forms a
pumpable slurry with the solids within said zone, pumping the
slurry from the zone with said slurry pump means until the solids
within the region adjacent said nozzle means are substantially
removed, directing additional liquid into a region underlying said
structure to form additional pumpable slurry with the mineral
solids and pumping the additional slurry away from said underlying
region to sink the nozzle means and slurry pump means downwardly to
a second region with said nozzle means located at a second
predetermined elevation below said first elevation, and repeating
the steps of directing at least one liquid stream from said nozzle
means into a path to define an additional pulping zone and pumping
slurry from said additional zone until the solids within said
second region are substantially removed.
4. A method as in claim 3 in which the settled body comprises a
tailings pond associated with an ore mining operation, and said
steps are repeated in a plurality of regions of the pond to remove
the mineral solids therefrom.
5. A method as in claim 3 in which said structure includes a
caisson, and said caisson is stabilized by a plurality of pilings
positioned circumferentially around said caisson and extending
vertically into the body of mineral solids adjacent thereto, and
the step of moving the nozzle means and slurry pump means includes
directing liquid into regions adjacent to and underlying said
pilings whereby the liquid forms a slurry with the mineral solids
therein sufficient to allow the pilings to sink by gravitational
action with the caisson through the slurry thus formed.
6. A method as in claim 3 in which said structure includes means
defining a sump positioned at the lower end of the structure and
means forming a portal opening in the structure to direct slurry
into said sump, including the steps of directing said stream of
liquid through said openings to establish said pulping zone
laterally adjacent the openings, causing said pumpable slurry to
flow by gravitational action from the pulping zone through the
portal openings and into said sump, and causing the slurry in the
sump to be pumped to a zone remote from the structure.
7. A method as in claim 3 in which said structure includes a
capsule, and said capsule is mounted for vertical movement with
respect to a plurality of stabilizing pilings positioned
circumferentially around said capsule and extending vertically into
the body of mineral solids adjacent thereto, and the step of moving
the nozzle means and slurry pump means includes directing liquid
into regions adjacent to and underlying said capsule whereby the
liquid forms a slurry with the mineral solids therein sufficient to
allow the capsule to sink downwardly by gravitational action
relative to the pilings.
8. Apparatus for removing discrete mineral solids from a settled
body of the same comprising a structure having a side wall, a lower
end adapted to extend below the upper surface of the body when the
structure is positioned therein, means forming a portal opening
through the sidewall providing fluid communication from a region of
the body surrounding said portal opening means into said lower end,
nozzle means forming a stream of liquid extending substantially
laterally outwardly through the portal opening means into said
region whereby the liquid forms a pumpable slurry with the solids
within a portion of said region defining a pulping zone, and means
to pump said slurry to a zone remote from the structure.
9. Apparatus as in claim 8 which includes means to stabilize said
structure within said body with said structure lower end positioned
at a first predetermined elevation below the upper surface of said
body, and means to move said structure downwardly to a second
elevation below said first elevation whereby operation of the
nozzle means and slurry pump means removes mineral solids from a
second region of said body below said first region.
10. Apparatus as in claim 9 in which said structure includes a
caisson carrying said nozzle means and slurry pump means, and said
stabilizer means comprises a plurality of pilings secured to said
caisson and circumferentially positioned therearound to extend
vertically into said body of solids whereby said caisson and
pilings move downwardly together.
11. Apparatus as in claim 9 in which said structure includes a
capsule carrying said nozzle means and slurry pump means, and said
stabilizer means comprises a plurality of pilings circumferentially
arranged around said capsule and extending vertically into said
body of solids, together with means mounting said capsule for
vertical movement with respect to said pilings.
12. Apparatus as in claim 11 which includes means forming a
platform at the upper ends of said pilings, together with hoist
means on the platform to raise and lower said capsule.
13. Apparatus as in claim 12 which includes means forming a service
bridge extending from said platform to the perimeter of said
body.
14. Apparatus as in claim 9 in which said means mounting said
capsule for movement with respect to said pilings includes guide
means comprising a plurality of guide shoes mounted for movement
with said capsule, each guide shoe extending radially outwardly
from the capsule into sliding contact with the outer surface of
respective ones of said pilings.
15. Apparatus as in claim 9 in which the means to move the
structure downwardly comprises means to direct at least one stream
of liquid into a region adjacent to and underlying said structure
lower end whereby said liquid forms a pumpable slurry with the
solids in said underlying region and the pump means pumps said last
mentioned slurry so that the structure sinks by gravitational
action into the volume of the underlying region from which said
slurry is removed.
16. Apparatus as in claim 15 in which said structure includes a
caisson, and said stabilizer means comprises a plurality of
circumferentially positioned pilings mounted for movement with the
caisson in vertical alignment therewith and having respective lower
ends extending below said body upper surface, and the means to move
the caisson downwardly includes means to direct a stream of liquid
in respective regions adjacent to and underlying said piling lower
ends whereby said liquid forms a slurry with the solids in said
underlying piling regions whereby said caisson and pilings sink
together by gravitational action.
17. Apparatus as in claim 8 in which said sidewall comprises an
elongate hollow shell having its longitudinal axis adapted to be
disposed vertically in said body of solids, and said means forming
the portal opening includes at least one opening in said shell
adjacent the caisson lower end.
18. Apparatus as in claim 17 in which the nozzle means comprises at
least one nozzle mounted within said shell to direct a liquid
stream outwardly through said portal opening means along a path
extending substantially laterally from the caisson to define said
pulping zone.
19. Apparatus as in claim 8 in which said portal opening means
includes an uppermost opening through which said liquid streams
extend, together with means forming a grating positioned below said
opening and through which said slurry flows to the pump means, said
grating comprising a plurality of vertically extending, laterally
spaced apart bars.
20. Apparatus as in claim 8 in which the means to pump the slurry
includes a sump formed in said structure lower end substantially
below said portal opening means whereby slurry flows by
gravitational action through said portal opening means into said
sump and said means to pump said slurry includes an inlet
communicating with said sump and an outlet adapted to discharge
pumped slurry upwardly through said structure.
21. Apparatus as in claim 20 wherein said structure forms a
substantially water-tight chamber position above said portal
opening means, together with pump operating means mounted within
said chamber connected to power said slurry pump means.
22. Apparatus for removing discrete mineral solids from a settled
body of the same comprising means forming a slurry receiving sump,
portal means for directing slurry into said sump, pump means for
pumping slurry from said sump to a zone remote therefrom, nozzle
means mounted above said sump for directing liquid streams
laterally into the mineral solids to form a slurry therewith, said
nozzle means being positioned within a diameter of the path of
travel defined by the movement of said sump through said settled
body, means for directing liquid under pressure to said nozzle
means, means for supporting said sump and nozzle means at
predetermined elevations within said settled body, and means for
injecting additional liquid into the mineral solids below said sump
to form additional slurry through which said sump and nozzle means
are caused to sink.
23. Apparatus as in claim 22 in which the support means includes
means for progressively lowering said sump and nozzle means while
said additional liquid is being injected below said sump for
controlling the elevation to which said sump and nozzle means are
lowered through the settled body.
24. Apparatus as in claim 23 in which said portal means is
positioned at an elevation below said nozzle means for receiving
slurry which is formed by the liquid from the nozzle means.
Description
CROSS-REFERENCES TO RELATED PATENTS AND APPLICATIONS
Reference is made to the following patents issued Sept. 20, 1971:
U.S. Pat. No. 3,606,036 entitled "Method and Apparatus for Shipping
Mineral Solids and Other Particulate Matter," U.S. Pat. No.
3,606,038 entitled "Ore Carrier with Slurry Repulping and Unloading
System," U.S. Pat. No. 3,606,479 entitled "Method and Apparatus for
the Storage and Pulping of Mineral Ores and Comparable Particulate
Matter;" and to application Ser. No. 213,363 filed Dec. 29, 1971
entitled "Liquid Jet Nozzle;" all of said patents and applications
are assigned to the present assignee.
BACKGROUND OF THE INVENTION
This invention relates in general to material excavation method and
apparatus, and in particular relates to method and apparatus for
the excavation and removal of a settled body of discrete mineral
solids such as a tailings pond from an ore mining operation or any
other settled body of material which may be constrained by any
means such as a large container or vessel and the like.
The mineral or ore solids which are normally discharged as waste
products from mining operations and the like must be disposed of in
a suitable manner. It is present practice in a mining operation to
deposit the tailings or waste mineral solids from operations such
as ore dressing into a tailings pond which may be a dammed up area
near the mining operation. The tailings pond contains the tailings
in a substantially homogeneous mass of water and mineral solids.
After a period of time this mass settles into a semi-rigid body of
discrete mineral solids as a certain percentage of the water is
expelled.
For various reasons including the fact that tailings ponds of the
above nature contain minerals of sufficient value to justify
economic recovery, or exist above unmined ore bodies that cannot be
mined with the tailings pond in place, or are so located as to
endanger entire communities should the associated retaining dam
break loose and the tailings ponds begin to flow, it is desirable
to excavate, remove, and transport away the mineral solids from the
pond. Present techniques such as clam shelling or dredging are
limited in their ability to do this work. In the above-identified
patents, in particular U.S. Pat. No. 3,606,479, there are disclosed
methods and apparatus for the handling of particulate material in
which a settled body of the material is removed by the action of
fluid jets mounted for operation in the lower-most region of the
containing vessel, such as a ship's hold. However, these methods
and apparatus are not applicable to excavation operations which can
be carried out from the surface of the settled body and progress
downwardly in stages to the required depth. Accordingly, the need
has been recognized for improved method and apparatus which is
effective in excavating and removing a settled body of mineral
solids of the above nature.
OBJECTS AND SUMMARY OF THE INVENTION
It is a general object of the invention to provide improved method
and apparatus which is applicable to removing a portion or all of a
settled body of material such as discrete mineral solids which may
be confined in the form of a pond or within a large container or
vessel and the like.
Another object of the invention is to provide method and apparatus
of the above character in which overlying regions of a body of
material such as mineral solids are removed in sequential stages
proceeding downwardly from the surface by pulping a lowermost zone
of each region with liquid into a slurry which is pumped away to
form an undercut cavity sufficient to cause collapse of the
overburden and with the overburden in turn pulped into a slurry and
pumped away.
Another object of the invention is to provide method and apparatus
of the above character which is applicable to excavating and
removing a settled body of material such as the mineral solids in a
tailings pond by means of a caisson apparatus which is partially
sumberged into the body and which carries nozzles adapted to direct
high velocity liquid streams into a pulping zone of an upper region
to be excavated, in which the liquid forms a pumpable slurry with
the solids with the slurry flowing through portals in the caisson
for removal by pumping, and in which the caisson apparatus is moved
downwardly for additional stages of excavation in the lower regions
of the body.
The foregoing and additional objects and features of the invention
are provided in the method wherein superposed regions of a settled
body of material, such as the ore solids in the tailings pond of a
mining operation, are excavated, removed and transported away for
subsequent disposition. The regions of the body are excavated in
step-by-step stages progressing downwardly from the surface to the
bottom of the pond or other container. The steps are then repeated,
as necessary, at another location in the pond until the desired
amount of material is removed.
In each region streams of high velocity liquid are directed along
paths in a lowermost pulping zone so that the liquid forms a
pumpable slurry with the solids within the zone. The slurry is
pumped away and the pulping action continues until an undercut
cavity is formed sufficient to cause collapse of the overburden.
The liquid streams form additional slurry with the collapsed
overburden which is also pumped away. Following this the streams of
liquid are moved downwardly to the next underlying region where the
foregoing steps are repeated until the mineral solids within the
latter region are excavated and removed.
In the apparatus an elongate caisson is partially submerged in the
body of solids with its longitudinal axis disposed vertically and
with its lower end extending below the upper surface of the body to
a depth which corresponds to the depth of the region to be
excavated. A plurality of nozzles are mounted within the caisson to
direct high velocity liquid streams through paths which extend
outwardly into the pulping zone. Portal means are formed in the
caisson to direct the flow of slurry into a sump. Pump means in the
caisson pumps the slurry from the sump through discharge conduits
leading to an installation or storage area remote from the pond. A
plurality of circumferentially positioned pilings are provided to
stabilize and position the caisson. In one embodiment both the
caisson and pilings sink downwardly as a unit through the pond,
while in another embodiment the pilings are stationary and the
caisson is raised and lowered relative to the piling. Jet means are
provided to sink the caisson by directing streams of liquid into
regions underlying the lower ends of the caisson and pilings in the
first mentioned embodiment, or into the region underlying only the
caisson in the second embodiment.
These and other objects and features of the invention will become
apparent from the following description and claims in which the
preferred embodiment is set forth in detail when taken in
conjunction with the accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a flow diagram illustrating the procedure for carrying
out the present invention;
FIG. 2 is a perspective view of a mineral ore tailings pond
undergoing excavation by caisson excavator apparatus constructed
according to one embodiment of the present invention;
FIGS. 3A and 3B comrpise an enlarged elevational view, partially in
longitudinal section and partially broken away, of the caisson
excavator apparatus of FIG. 2;
FIGS. 4A and 4B comprise a view similar to FIG. 3 of caisson
excavator apparatus constructed according to another embodiment of
the invention; and
FIG. 5 is a fragmentary cross-sectional view taken along the line
5--5 of FIG. 4.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
In the drawings FIG. 1 shows a flow sheet illustrating the method
of the present invention applied in the excavation and removal of a
settled body of material such as discrete mineral solids, e.g.,
iron, copper or molybdenum ore filtrates, muds or waste residue and
the like. While the method of the invention will be described as
carried out by apparatus specially adapted for excavating a
tailings pond associated with a mining operation, it is understood
that the invention has broad application in the excavation and
removal of other settled bodies of solids of this nature, such as a
body of material solids confined by other means which could
comprise a large container or vessel of any type, and in which the
solids are adapted to be formed into a pumpable slurry. The above
identified issued patents contain details of the types, size and
characteristics of mineral solids of this nature which are capable
of being excavated and removed by the method and apparatus of the
present invention. The term mineral solids as used herein includes
ores, dressed ores and all other particulate matter and ore
products capable of being pulped into a pumpable slurry.
In the method a region of the solids body is selected for the first
stage of excavation. High velocity streams of liquids, which
preferably would be water although other suitable non-aqueous
liquids could be used, are directed in step 10 into a pulping zone
at the bottom of the first region which is established at a
predetermined elevation below the upper surface of the body. The
water streams or jets impact with the solids which are caused to
break up and disperse for suspension in the water as a slurry in
step 12. This slurry is pumped away from the pulping zone at step
14 for transport to a subsequent processing operation remote from
the settled body. The streams are transversed along predetermined
paths in step 16, such as back and forth traversing through
individual arcs extending across the pulping zone, and the action
of the water progressively breaks up and disperses the solids
within the area of influence of the streams. Simultaneous pumping
and removal of the slurry thus formed progressively extends the
area of influence of the streams so that an undercut cavity is
gradually formed in the first region. The foregoing steps continue
at step 18 until the overburden of solids above this cavity is
caused to collapse by its own weight and fall into the pulping
zone. The water streams are continually traversed along their paths
at step 20 so as to form additional slurry with the solids of the
overburden which has collapsed into the pulping zone. This
additional slurry is then pumped away at step 22. The action of the
water streams and slurry pumping is continued until the desired
volume of solids is removed from the first region.
Following the first stage of excavation, the second stage is
initiated, as required, for excavating and removing the solids in a
second region at 24 underlying the first region. In the second
stage high velocity water streams or jets are established in step
26 and directed into a pulping zone located at the bottom of the
second region. Following this the remaining steps described for the
first stage are repeated. Thus, a pumpable slurry is formed in step
28, and this slurry is pumped away in step 30. In step 32 the
streams are traversed to form an undercut cavity in the second
region, and in step 34 the overburden is collapsed. The collapsed
overburden is formed into additional slurry in step 36, and this
latter slurry is simultaneously pumped away in step 38, with these
steps continuing until the desired volume of solids is removed from
the second region.
It will be seen that the number of stages of operation of the
described steps required to excavate a given portion of the solids
body will be determined by various factors including the depth at
which the water streams are established in each region, and the
overall depth of the solids body. Following excavation of the
overlying regions to the bottom of the body, e.g., the floor of a
tailings pond, the operation would be repeated in other locations
of the pond depending upon the area size of the body and the amount
of solids desired to be removed from the body.
In FIGS. 2, 3A and 3B, there is shown as one embodiment suitable
apparatus for carrying out the invention in the excavation of a
settled body of mineral solids comprising a tailings pond 40
associated with a mining operation. The tailings pond would
typically comprise a dammed up area of land which contains, for
example, the tailings or waste ore discharged from an ore dressing
operation. The tailings body generally is an homogeneous mixture of
ore particulate matter and water and is characterized in having low
compression and shear strength and very high viscosity.
In the embodiment of FIGS. 2, 3A and 3B, the excavator apparatus 42
includes a large elongate caisson structure 44 adapted to partially
extend into the tailings pond with its longitudinal axis vertically
aligned. Caisson 44 comprises an outer shell 46, preferably of a
cylindrical configuration, strenghtened by means of a plurality of
axially spaced ribs 48. The caisson is divided by means of
watertight bulkhead 50 into a water jet and pump compartment 52 at
the caisson lower end and a watertight upper chamber 54. Caisson
shell 46 is mounted to and extends downwardly from a deck structure
56 forming an operator and equipment platform. The lower end 58 of
the caisson is conical in shape to facilitate the sinking action of
the apparatus in a manner to be described hereafter.
Portal means comprising a plurality, preferably four, of openings
60, 62 are formed in the sidewalls of the caisson shell at the mid
portion of the jet and pump compartment 52. Four high pressure
water jet nozzles 64, 66 are mounted at 90.degree. orientation
within the caisson compartment 52 in a manner to direct streams of
high velocity water outwardly through the upper portions of
respective ones of the portal openings 60, 62. The nozzles are
aimed to direct the jets approximately horizontally, although they
could be canted upwardly somewhat. Details of the construction and
operation of the nozzles 64, 66 are described in the above
mentioned application Ser. No. 213,363.
The high pressure nozzles are adapted to convert a high pressure
source of water into a high force water stream or jet with low
energy losses for a highly efficient cutting action against the
body of mineral solids which surround the caisson. Suitable sensor
and water pressure controls as described in said issued U.S. pat.
No. 3,606,479 may be provided for controlling the solid to fluid
ratio of the slurry, and to compensate for an increase in
peripheral traversing speed of the streams as the working range
increases. While nozzles and control arrangements of the type
described in said issued patent would be preferred in the present
invention, it is understood that other suitable fluid nozzles and
controls could be utilized.
The nozzles 64, 66 are supplied by the high pressure water through
respective water conduits 68, 70 which are mounted within the
caisson shell and extend downwardly from respective swivel joint
connections 72, 74. The swivel connections in turn are connected
through suitable manifold piping 76 with water inlet connection 78
and inlet supply piping 80 (FIG. 2), which may comprise a series of
flexible interconnected pipes affixed to suitable pontoon type
supports resting on the surface of the tailings pond. A shore
installation, not shown, provides suitable pumping apparatus and
the source of supply water for directing water under a pressure of,
for example, 300 psi into supply piping 80.
Means are provided to control the direction of the water streams
jetting from each of the nozzles, and this means includes a
plurality of reciprocating hydraulic actuating cylinders 82, 84
mounted within the caisson and connected through operating arms 86,
88 to swivel the conduits 68, 70, and thereby the individual
nozzles back and forth through an arc of rotation. The actuating
cylinders are operated under influence of suitable automatic and
manually operated hydraulic valves incorporated into a control
stand 90 on deck 56 with pressurized hydraulic fluid supplied from
suitable pump means contained in power unit 91. Relative rotational
movement at the upper ends of piping 68, 70 is accommodated through
the swivel joints 72, 74, and at the lower end thereof through
suitable ring seals 92, 94 mounted around openings provided in
bulkhead 50.
The portal openings 60, 62 are covered at the portion thereof below
the arc of travel of the liquid streams by means of suitable grates
96, 98 preferably formed in a grizzly-type construction having a
plurality of vertically extending, laterally spaced-apart bars
adapted to permit the gravital flow of slurry from around the
caisson through the portal openings and down into a sump or pump
penstock 100 at the bottom of compartment 52. A plurality of slide
gates 102, 104 are mounted within the caisson for vertically
sliding movement to selectively cover and uncover the portal
openings. The gates are moved up and down by suitable means
comprising respective hydraulic cylinders 106, 108 mounted above
bulkhead 50 within the sealed chamber 54 and having actuating arms
extending through the bulkhead for connection with the gates. The
cylinders 106, 108 are actuated by hydraulic pressure under
influence of suitable manually operated control valves contained in
the control stand 90. Each of the four gates are raised to the
position illustrated by gate 102 to permit operation of the main
excavating nozzles, and these gates are lowered to the position
illustrated by gate 104 where it is desired to close off the flow
of slurry into the sump, and at such time operation of the main
nozzles 64, 66 would be shut down. In the invention the geometry
and relationship of nozzles, portal openings, grates and slide
gates facilitate the excavation operation which progressively moves
from the surface of the settled body downwardly in stages.
Means is provided for pumping the slurry flowing into sump 100 away
from the caisson, and this means comprises a suitable vertical
drive slurry pump 110. The pump 110 includes a downwardly and
outwardly flaring inlet 112 through which the slurry is raised from
the sump. Slurry discharge from the pump is directed upwardly
through a discharge conduit 114 extending through an opening in
bulkhead 50 into upper chamber 54 where it connects into discharge
piping 116. The flow of discharge slurry continues through a
one-way valve 118 and piping 120 mounted within the caisson shell
and leading into slurry discharge fitting 122 which in turn is
connected with suitable flexible discharging piping 124. The
discharge piping 124 may comprise a series of flexible
interconnected pipes mounted on pontoon-type supports to rest on
the surface of the tailings pond. The discharge piping in turn
leads to the shore installation for the desired subsequent
processing operations.
Slurry pump 110 is powered by suitable means comprising an electric
motor 126 mounted within sealed chamber 54 and connected with the
pump through drive shaft 128. This electric motor is operated
through suitable automatic and manual controls and switching
contained within motor control cabinet 130 on deck 56.
Stabilizer means is provided to stabilize the caisson vertically
within the structurally weak settled body and this stabilizer means
comprises a plurality, preferably four, of elongate pilings 132,
134 mounted below deck 56 to extend partially into the body. The
four pilings are arranged in circumferentially spaced-apart,
parallel relationship around the caisson located along radii
extending from the caisson between the nozzle positions so that the
pilings do not obstruct the path of travel of the liquid streams.
Each of the pilings comprise hollow members which may be tubular
piping formed at their lower ends with conical caps 136, 138 to
facilitate the sinking action of the pilings in a manner to be
described hereafter. Suitable means is provided to brace the
pilings with the caisson, and this bracing comprises four cross
members 140 each extending between an adjacent pair of the pilings,
together with a plurality of cables 142, 144.
Four guy lines 146, 148, 150, 152 are provided to afford additional
stability for the caisson, and a vertical alignment capability. The
guy lines extend from respective ones of four hydraulically
operated winches 154, 156 mounted on the four corners of the
caisson deck. Each of the guy lines extend across the excavation
cavity where they are anchored by suitable means along the edge of
the excavation, as best illustrated in FIG. 2. Operation of the
winches 154, 156 as the caisson and pilings are submerged and sink
into the tailings pond permits an adjustment or correction of the
vertical angle of the caisson. With the caisson stabilized at the
desired depth the guy lines are maintained under tension to provide
lateral tability.
Means is provided to sink excavator apparatus 42 downwardly in
step-by-step increments for successive excavation of the superposed
regions in the solids body. This sinking means comprises a
plurality of nozzles 158, 160 mounted in caisson lower end 58, and
a plurality of nozzles 160 mounted in respective ones of the four
piling end caps 136, 138. The caisson mounted nozzles 158, 160 are
arranged to direct water jets or streams downwardly into a region
of the solids material adjacent to and underlying the caisson lower
end, and these nozzles are arrayed in a pattern providing maximum
distribution of the water jets to form a pumpable slurry with the
solids underlying the caisson. Thus, it is preferred to provide
four nozzles 158 arranged at 90.degree. radii about the
longitudinal axis of the caisson and with a single nozzle 160
concentrically arranged at the apex of the conical end. Water under
high pressure is provided through inlet manifold piping 164 to
nozzles 158 and through branch conduit 165 to nozzle 160. The
manifold piping 164 is fed by water supply conduit 166 extending
down through the caisson shell and connected at its upper end
through suitable flow control valve means, not shown, with the
piping leading from high pressure water inlet 78.
The piling sink nozzles 162 are arranged to direct high pressure
water jets or streams downwardly into regions of the solids
material underlying the piling ends. Water is supplied to each of
the piling sink nozzles through conduits 168, 170 extending
downwardly within the interior of respective pilings and connected
at their upper ends through suitable supply conduits 172, 174 and
flow control valves, not shown, leading from high pressure water
inlet 78. The flow control valves for both the caisson sink nozzles
and piling sink nozzles are operated by means of suitable manual
controls accessible from deck 56.
A pump flushing nozzle 176 is mounted within the lower end of the
caisson to direct a high pressure water jet or stream vertically
upwardly through the approximate center of slurry sump or penstock
100 and into the throat of pump inlet 112. Water is supplied to the
flushing nozzle 176 through a supply conduit 178 extending
downwardly through the caisson shell and connected at its upper end
through a suitable flow control valve, not shown, leading from high
pressure water inlet 78. The flushing nozzle control valve is
selectively actuated for jetting high pressure water into the sump
where it is desired to agitate the pulp therein for starting an
excavation operation after a period of shut down, and to clear out
the sump.
An example of the construction and operation of an application of
the first embodiment of the invention as used for excavating a
tailings pond associated with a mining operation is as follows: A
caisson excavator apparatus is constructed in accordance with the
disclosure herein so that the tip of caisson lower end 58
penetrates approximately 36 feet below the orginal pond surface
180. The depth of the lower edges of portal openings 60, 62 below
this surface is 30 feet, and this defines the working depth of the
first region to be excavated. The four pilings 132, 134 project
downwardly alongside the caisson to a depth of approximately 43
feet below surface 180, thereby providing a penetration for the
pilings of approximately 13 feet below the portal openings so that
sufficient stability is afforded for the caisson apparatus as the
solids are excavated from around the caisson to the level of the
portals.
The first region of the trailings pond to be excavated is initially
prepared for receiving the caisson apparatus by forming a hole, as
by clam shelling, with a diameter sufficient to accept the caisson
shell. Four smaller peripheral holes for receiving the pilings are
formed around the caisson hole by suitable means such as drilling.
The caisson apparatus is then lifted, as by an overhead crane,
centered over the holes, and dropped therein to the depth for the
initial stage of excavation in the first region of the pond. The
four guy lines 146-152 are payed out from the winches and anchored
at suitable radial distances which would lie outside the perimeter
of the pond or cavity area to be excavated. The inlet piping 80 and
discharge piping 124 is next installed on the pontoon type supports
and connected with the inlet and outlet fittings on the caisson
deck. Water under a pressure on the order of 300 psig is directed
from the shore installation through the inlet piping and the
various supply lines are filled and pressurized.
The first stage of operation is commenced by raising the slide
gates 102, 104 and opening the flow valves leading to nozzles 64,
66. High velocity water streams are directed from the four nozzles
through the spaces in the portals above grizzlies 96, 98 to
penetrate into the solids material surrounding the portals. The
water forms a pumpable slurry with the solids and this slurry flows
by gravity through the grizzlies and downwardly into sump 100. Pump
motor 126 is energized to operate pump 110 which removes this
slurry and discharges it through the discharge conduits and piping
to the shore installation. The four water streams are traversed
back and forth through arcs of travel which extend transversely
from the caisson and which together define a pulping zone lowermost
of the first region. These streams are traversed by operation of
hydraulic actuating cylinders 82, 84 which swivel the associated
piping conduit 68, 70 and nozzles. The desired cutting action and
penetration into the material, together with the desired ratio of
solids to liquid for optimum slurry pumping characteristics, is
maintained through control of the traversing speed and pattern of
the water streams, and control of the water pressure. The
traversing speed is controlled within the range of one-fourth rpm
and up to 6 rpm, and the traversing pattern may be controlled so
that the streams remain stationary for deeper penetration for a
given time followed by a relatively constant rotational speed
across to and back from the extreme limit of their arc of travel.
This pattern of water stream traversal, forming of the slurry
within the pulping zone, and removal of the slurry by pumping
progresses so that an undercut cavity is gradually formed which
extends outwardly around the periphery of the caisson portals.
Eventually this cavity enlarges so that the overburden of material
above the cavity collapses and falls by gravity into the pulping
zone. Operation of the water streams through their traversing
patterns continues so that this collapsed overburden is formed into
additional slurry which flows through the portals and into the sump
where it is pumped away. These operating steps are continued until
the outer limits of the area of influence of the water streams is
reached. At this point the caisson apparatus is prepared for
sinking to the next lower region for a second stage of excavation
by shut down of the valves feeding main nozzle 64, 66.
Caisson apparatus 42 is sunk downwardly into the solids material to
the next lower region by opening the flow control valves supplying
water into the caisson sink nozzles 158, 160 and piling sink
nozzles 162. Water issuing from the caisson sink nozzles forms a
pumpable slurry with the material underlying the caisson lower end,
and the weight of the caisson is effective to displace this slurry
upwardly around the outer surface of the caisson shell where it can
flow through the grating of the portal and into sump 100 where it
is pumped away. The slurry which is formed below the ends of the
four pilings is sufficiently fluid so that the relatively small
frontal area of the pilings displaces the slurry material aside as
the pilings drop by gravity. Operation of the caisson and piling
sink nozzles and sump pumping action continues so that the caisson
gradually sinks into the tailings pond, with vertical stability and
angular correction being provided through operation of the four guy
line winches 146-152. This sinking step continues until the portal
openings drop to an elevation or depth on the order of 30 feet from
their original position. This dimension thus defines the depth of
the second region of the pond to be excavated. Second stage
operation is initiated by opening the flow control valves to the
main nozzles 64, 66 which are traversed in the manner explained
above through their respective arcs of travel into a pulping zone
in this second region. The steps of forming and pumping away the
slurry in the pulping zone to form an undercut cavity, collapsing
the overburden, and forming and pumping away the slurry formed with
the overburden are repeated in the manner previously explained
until the limits of the area of influence of the water streams are
reached in the second region.
When the second region is completely excavated the caisson
apparatus is sunk downwardly to successively lower regions which
are excavated in further stages of operation until the floor of the
tailings pond is reached. Following this the caisson apparatus is
moved to another area of the pond which is excavated in the
foregoing manner.
FIGS. 4-5 illustrate an embodiment of the invention characterized
in providing a capsule 184 adapted to be raised and lowered with
respect to fixed pilings 186, 188 whereby the excavation operation
may be easily controlled, maintenance of the equipment within the
capsule is facilitated, and problems associated with the flooding
or sedimentation of the capsule are obviated.
A plurality of the pilings, shown as four, comprising steel piping
are driven into the body of material, such as a tailings pond, at
circumferentially spaced positions about the center of the desired
excavation location. These pilings extend into the floor or bedrock
formation of the pond and project upwardly above the initial pond
surface 190. A service platform 192 is mounted on the uwpardly
projecting ends of the four piles. A plurality of guy wires and
associated guy tensioning winches 193 are mounted on the platform
with the ends of the wires anchored around the pond perimeter. The
platform also supports a control and hydraulic power unit enclosure
195.
A service bridge 194 is secured at one end to service platform 192
and extends to the perimeter of the pond where it is supported on
suitable foundation structure such as a dike, not shown, which
would be provided to dam up the tailings pond. Additional support
for the service bridge may be provided by driving groups of pipe
piles, not shown, into the bedrock to form supporting bents at
intermediate locations along the length of the bridge. Service
bridge 194 provides access to the service platform for lowering
subsections of the capsule through platform opening 196 for
assembly between the four piles. Additionally, the bridge provides
support for water supply piping 198 and slurry discharge piping
200, and for maintenance and repair access to the service
platform.
Capsule 184 comprises a housing structure 202 of cylindrical shell
configuration which includes an upper water-tight equipment
compartment 204, separated from a lower water-jet and pump
compartment 206 by means of a sealed bulkhead 208. The lower end of
the capsule is defined by conical shell 210 and the upper end is
defined by sealed cover 212 provided with an access opening closed
by hatch 214 which leads to ladder 215. Flexible lines 216, 217
provide hydraulic and electrical power and control communication
between enclosure 195 and the capsule.
Portal opening means comprising a plurality, preferably four, of
openings 218 are formed at spaced-apart positions around the
perimeter of jet and pump compartment 206. Four high pressure
water-jet nozzles 220, preferably of the construction and operation
as described in the above referenced application, Ser. No. 213,363,
are mounted at 90.degree. orientation within compartment 206 to
direct high velocity water streams outwardly through the upper
margins of respective portal openings. Each of the nozzles depend
from pipe sections 222 which in turn are sealably mounted for
pivotal movement in packing glands 224 extending through bulkhead
208. Rotary actuated means 226 is mounted within equipment
compartment 204 in operating connection with pipe sections 222 for
oscillating the respective nozzles and thereby controlling the
direction of the water streams jetting from each nozzle. High
pressure water is supplied to the nozzles through the inlet piping
198 on the service bridge from a pumping installation at a suitable
location remote from the pond. One or more removable sections of
piping 228 are connected to inlet piping 198 through elbow fittings
230 and to capsule 184 through supply piping 232 mounted within the
equipment compartment. A circular supply manifold 234 is connected
with the lower end of piping 232 and feeds supply water into branch
pipe sections 236 leading to respective nozzles. One or more of the
piping sections 228 leading to the capsule may be installed or
removed, as desired, for purposes of lowering or raising the
capsule with respect to the service platform.
The portions of portal openings 218 below the arc of travel of the
liquid streams are covered by suitable grates 238, preferably of a
grizzly-type construction having a plurality of vertically
extending, laterally spaced-apart bars 240. The grates receive the
gravital flow of slurry from around the capsule through the portal
openings and into the sump or pump penstock 240 defined within
compartment 206. Each portal opening is provided with a slide gate
242, 244 mounted for vertical sliding movement above a respective
opening. The actuating means for each gate comprises four
extensible hydraulic cylinders 246, 248 mounted within equipment
compartment 204 above each gate position with the actuating rods of
the cylinder extending through bulkhead 208 for connection with the
gates. With the rods of the actuating cylinders retracted the gates
are raised to the position illustrated by gate 242 to permit
operation of the associated nozzle. With the rods extended the
gates are lowered to the position illustrated by gate 244 for
closing off the flow of slurry to the penstock.
Slurry which flows into penstock 240 is removed by a submersible
slurry pump 250 having a downwardly facing, outwardly flaring inlet
252 suspended within the penstock and driven by power shaft 254
from electric motor 256 mounted within the sealed equipment
compartment. Two outlets from the pump direct the discharge of
slurry through piping 258, 260 leading through bulkhead 208 and
into outlet manifold 262 which in turn is connected into discharge
piping 264 leading upwardly through the equipment compartment. One
or more removable sections of the piping 266 are connected between
the upper ends of piping 264 and elbow fitting 268 connected to the
slurry discharge piping 200. The piping 200 extends along the
bridge to shore based piping for delivery to a suitable receiving
installation remote from the pond. As the capsule is incrementally
lowered additional sections of piping 266 are installed as in the
case of the water inlet piping 228, and conversely the discharge
sections are removed as the capsule is raised.
Water jet and pump compartment 206 of the capsule is additionally
provided with a pump flushing nozzle 270 mounted within the
lowermost portion of the penstock and positioned to direct a water
jet, under influence of suitable controls provided in enclosure 195
on the service platform, into pump inlet 252 for use during
initiation of an excavation operation after a period of shutdown,
and to clean out the sump. Water under pressure is supplied to the
flushing jet by feed piping 272 and a suitable control valve, not
shown, connected with the high pressure water inlet circuit.
Capsule 184 is mounted for vertical movement with respect to the
four piles 186, 188 by means of four capsule guide assemblies 274,
276 secured to and projecting outwardly from the capsule housing
radially inwardly of respective pilings. Capsule guide assembly 204
of FIG. 5 is typical and comprises a capsule guide weldment 278
having a base plate 288 secured by means such as welding to the
capsule's outer shell structure 202. The weldment is formed with an
outwardly projecting yoke 290 into which the supporting rib 292 of
a guide shoe plate 294 is mounted by means of locating pin 296. The
guide shoe plate is arcuate in shape for sliding contact with the
adjacent piling. The capsule guide weldment is further formed with
an opening 298 for receiving the lower end of an elevating hoist
cable 300 which is secured to the weldment by means of lockpin 302.
Four hoist cables 300 lead upwardly from each guide assembly to
respective hydraulically operated elevating hoists 304, 306 mounted
on the service platform. The elevating hoists are operated under
influence of suitable controls provided within enclosure 195 to
raise and lower the capsule to a selected elevation, with the four
guide shoe plates maintaining vertical alignment of the capsule
with respect to the four pilings.
Means are provided to sink the capsule through the tailings
material for excavation of a next lower region. This means includes
a plurality, preferably four, of sink jets 308, 310 mounted
circumferentially about the capsule's conical shell 210 in an
orientation to direct jets of water downwardly to form a slurry
with the tailings immediately below the capsule. The weight of the
capsule causes this slurry to displace upwardly and flow through
the portal openings as the capsule sinks while at the same time the
elevating hoist cables are payed out. Operation of the sink jets
continues until the capsule reaches the next lower incremental
position, for example 20 feet below the first level, whereupon the
elevating hoists are locked to stabilize the capsule in position.
Water under pressure is supplied to the sink jets by circular
manifold piping 312 through four branch conduits 314 with this
manifold supplied by piping 316 connected with the water inlet
piping through suitable flexible conduits and valving, not shown,
operated under influence of controls provided within enclosure 195
on the service platform.
An example of the use and operation of the embodiment of FIGS. 4-5
in the excavation of a tailings pond is as follows: Four 20 inch
diameter pipe piles 186, 188 are driven through the pond and into
the underlying bedrock, with a 20 foot square service platform 192
constructed across the projecting tops of the piles. An 8 foot wide
bridge 194 is constructed from this platform to the pond perimeter.
Three stabilizing guy wires are secured to suitable foundations at
the perimeter of the pond and tensioned respectively by three
winches 193.
Capsule 184 is assembled in situ between the piles by moving four
capsule subsections across the bridge to the service platform. Each
section is lowered in turn through platform opening 196 for
assembly of the complete capsule. The hydraulic power unit and
control system is installed within enclosure 195 with flexible
hydraulic and electrical lines 216, 217 attached to the capsule.
High pressure water inlet piping 198 of 6 inch diameter is
installed across the bridge to suitable shore-based pumping
equipment capable of supplying water at 1,300 GPM and 400 PSI.
Slurry discharge piping 200 of 12 inches diameter is installed
along the bridge to a suitable shore-based tailings underflow sump
to which the slurry is to be discharged. A flexible inlet line, not
shown, is installed between the high pressure inlet piping 198 and
piping 316 leading to the sink jets.
Capsule 184 is lowered to its first operating position at which a
lower margin of the portals are 20 feet below the pond's initial
surface 190 by first actuating the sink jets 308, 310. The water
issuing from the sink jets impinges upon the tailings material
below the capsule to form a slurry which is displaced upwardly by
the weight of the sinking capsule. As the capsule sinks it is
stabilized and guided downwardly by the four guide shoes 294. This
action continues as the four elevating hoists 304, 306 are payed
out. When the first operating position is reached the sink jets are
shut down and the elevating hoists locked to secure the capsule in
position. Twenty foot sections of pipe 228, 266 for both the inlet
and discharge lines are then installed.
With high pressure water supplied to the inlet piping, excavation
at the first position is initiated by operating the controls to
raise one of the slide gates 242 to open the valve controlling flow
to the associated nozzle 220, and to energize the rotary actuator
226 which will oscillate the nozzle and water stream back and forth
through an arc of travel extending outwardly through the portal.
The high velocity stream impinges upon and forms a slurry with the
surrounding tailings material. This slurry flows by gravity through
portal opening 218 and into penstock 240 from which it is
discharged by pump 250. As excavation progresses the cavity
enlarges across the arc of travel of the water jet to the extent
that the overburden of tailings collapses by gravity to form
additional slurry. When the cavity surrounding the first portal
enlarges to the desired extent, flow through the nozzle is shut
down and the slide gate is closed. Following this the portions of
the tailings extending outwardly from the remaining three portal
openings are excavated in successive order by similar steps so that
a complete circular volume about the capsule is excavated.
Capsule 184 is prepared for lowering to the next lower region by
disconnecting the inlet and discharge piping sections 228, 266. The
sink jets are activated to direct high pressure water jets into the
tailings to sink the capsule as the elevating hoists are operated
to pay out their cables. When the capsule reaches the second
operating position at an elevation of 20 feet below that
illustrated in FIG. 4, the elevating hoists are locked and sink jet
operation is terminated.
Additional 20 foot sections of inlet and discharge piping are then
inserted. Horizontal bracing, not shown, is constructed across the
four pilings 186, 188 at lower elevations for added support as
material is removed from around the piles. At the second operating
position the steps described above are repeated for removal of the
surrounding volume of tailings.
After excavation is completed, the capsule may be raised by
disconnecting and removing one or more sections of both the inlet
and discharge piping and then operating the elevating hoist. For
example, the capsule would be raised where the tailings pond is
again being filled with material. Also, additional excavation
installations within the same pond may be provided by constructing
similar groups of four pilings, erecting additional service
platforms and service bridges, and using one capsule for the
overall operation. Thus, following excavation at one installation
the same capsule would be disassembled and transported for assembly
and operation at a second installation.
While the embodiment of FIGS. 4, 5 illustrate apparatus and method
in which the capsule, when excavating at each vertical operating
position, is fixed with respect to the piles, the invention also
contemplates a construction which accommodates minor changes in
elevation between the capsule and pilings as excavation proceeds.
For example, the inlet and discharge piping sections between elbow
fittings 230, 268 and the capsule could be of telescoping design.
In addition, the inlet and discharge piping sections could be
replaced by a swivel joint X design to permit the capsule to
undergo changes in elevation with respect to the pilings. For ocean
mining the pilings could be replaced in function by a nose cone
stabilizing spud so that the capsule could operate independently at
greater depths with suitable inlet and discharge conduits and power
and control cables extending to a surface vessel.
It is apparent that there has been provided in the invention new
method and apparatus which facilitates the excavation of a settled
body of material such as a tailings pond through operations which
proceed downwardly from the surface. The embodiment of FIGS. 1-3
provide a caisson with attached pilings. In the embodiment of FIGS.
4, 5 a capsule moves relative to fixed pilings, and the excavating
operation may be controlled as the cavity area increases by
progressively lowering the capsule to the desired depth. In
addition, the provision of the fixed service platform and access
bridge facilitates maintenace or repair of the equipment, and in
particular the capsule can be hoisted to the service platform at
any time. Moreover, the capability of hoisting the capsule obviates
problems which could arise due to flooding and compaction of slurry
within the water jet and pump compartment.
While the foregoing embodiments are at present considered to be
preferred for use in the excavation of a tailings pond, it is
understood that numerous variations and modifications may be made
therein by those skilled in the art and that the invention will
find application in removing settled bodies of material of the
foregoing nature confined in any relatively large body, container
or vessel, and it is intended to cover in the appended claims all
such variations, applications and fields of use as fall within the
true spirit and scope of the invention.
* * * * *