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Claims  |
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I claim:
1. An apparatus for generating at least one particulate containing fluid
jet stream comprising:
a pressurized fluid supply means connected to at least one pressurized
fluid supply conduit;
a particulate supply means connected to at least one particulate supply
conduit;
a nozzle assembly fluid-tightly joined to said pressurized fluid supply
conduit and said particulate supply conduit, said nozzle assembly
comprising at least one fluid jet nozzle means having at least one orifice
means in communication with said pressurized fluid supply means; at least
one mixing chamber wherein particulates are mixed with and entrained in at
least one fluid stream aligned with said orifice means and in
communication with said particulate supply means; and a particulate valve
body housing a particulate valve means capable of closing and opening a
flexible portion of said particulate supply conduit, said particulate
valve means is adjacent said flexible portion of said particulate supply
conduit and comprises a valve piston having a side recess facing said
conduit, a valve ball retainable in said side recess opening said flexible
portion of said particulate supply conduit and closing said conduit when
said piston is moved to a position said ball is not retained in said
recess moving said ball through a valve ball passage provided in said
particulate valve body housing to close said flexible portion of said
particulate tube, a valve piston spring providing a force against a first
end of said valve piston, and a valve stem means fixedly attached to said
first end of said valve piston, said valve stem means extending external
to said valve means providing opening and closing of said particulate
valve means external to said nozzle assembly.
2. In an apparatus of the type comprising a pressurized fluid supply means
connected to at least one fluid supply conduit, a particulate supply means
connected to at least one particulate supply conduit, a nozzle assembly
joined to said pressurized fluid supply conduit and separately joined to
said particulate supply conduit and capable of generating at least one
particulate containing fluid jet stream, the improvement comprising: a
particulate valve means within said nozzle assembly which automatically
closes a flexible wall particulate supply conduit when said pressurized
fluid supply means is inactivated and automatically opens said flexible
wall particulate supply conduit when said pressurized fluid supply means
is activated, said particulate valve means comprising a valve piston
movable within a cylinder substantially parallel to said flexible wall
particulate supply conduit within said nozzle assembly and having a side
recess facing said flexible wall particulate supply conduit; a valve ball
sized to fit adjacent said piston away from said side recess forcing said
flexible particulate supply conduit closed when said valve piston is moved
to a first position by force of a bias spring force against a first end of
said piston, and sized to fit within said piston side recess when said
valve piston is moved to a second position by force against an opposite
second end of said piston caused by said pressurized fluid thereby opening
said flexible particulate supply conduit for supply of particulates to
said particulate containing fluid jet stream, said pressurized fluid force
caused by passage of said pressurized fluid from said fluid supply conduit
through fluid passage means within said nozzle assembly.
3. In an apparatus according to claim 2, wherein said valve piston is moved
to said second position when said force of said pressurized fluid exceeds
said force of said force of said bias spring.
4. In an apparatus according to claim 3, wherein a valve plunger extends
from said second end of said piston slidably through a valve plunger
cavity, said pressurized fluid providing a force against the end of said
valve plunger thereby applying force against said second end of said
piston.
5. In an apparatus according to claim 2, wherein a valve plunger extends
from said second end of said piston slidably through a valve plunger
cavity, said pressurized fluid providing a force against the end of said
valve plunger thereby applying force against said second end of said
piston.
6. In an apparatus according to claim 2, wherein said recess has smooth
diverging peripheral portions to facilitate movement of said valve ball
into and out from said recess.
7. In an apparatus according to claim 2, wherein a valve stem extends from
said first end of said valve piston to the exterior of said nozzle
assembly providing manual operation of said particulate valve means.
8. In an apparatus according to claim 2 additionally comprising at least
one flow shaping cone aligned with said at least one orifice means, each
said flow shaping cone having a central passage for issuing a particulate
containing fluid jet stream.
9. In an apparatus according to claim 2 comprising of two said fluid jet
nozzle means, each said fluid jet nozzle means having a centrally arranged
orifice means, wherein said nozzle means are oriented substantially
opposite one another and said orifice means are oriented to generate
diverging fluid streams at an angle of about 30.degree. to about
90.degree. from a central axis of said nozzle assembly.
10. An apparatus according to claim 9 wherein said nozzle means are
oriented in different planes offset slightly from one another.
11. In an apparatus according to claim 2 wherein said pressurized fluid
conduit and said particulate supply conduit are flexible hoses and said
apparatus additionally comprises a tube/hose adapter attached to said
pressurized fluid conduit and said particulate supply conduit, at least
one particulate tube and at least one rigid high pressure fluid tube
fluid-tightly attached at one end to said tube/hose adapter and at the
other end to said nozzle assembly for conveying particulates and fluid
streams, respectively, from said supply means to said nozzle assembly.
12. An apparatus according to claim 11 wherein said at least one
particulate tube and said at least one rigid high pressure fluid tube are
enclosed by a rigid cover tube attached at one end to said tube/hose
adapter and at the other end to said nozzle assembly.
13. An apparatus according to claim 11 wherein said tube/hose adapter
comprises a high pressure fluid manifold diverting high pressure fluid
from said pressurized fluid conduit into at least two said high pressure
fluid tubes.
14. In an apparatus according to claim 2 wherein said particulate supply
means comprises a flow controller to regulate the flow of particulates
therefrom and said flow controller is in communication with said
pressurized fluid supply means and releases particulates only when said
pressurized fluid supply means is activated.
15. In an apparatus according to claim 2 wherein said nozzle assembly is
provided with a plurality of particulate passages diverging from said
particulate supply means and each said particulate passage terminates in a
mixing chamber aligned with at least one fluid jet nozzle means.
16. In an apparatus according to claim 2 comprising a plurality of fluid
jet nozzle means.
17. In an apparatus according to claim 2 additionally comprising a
discontinuity generator means provided in proximity to each said fluid jet
nozzle means.
18. In a process of the type comprising supplying a pressurized fluid
through at least one fluid supply conduit and particulates through at
least one particulate supply conduit to a nozzle assembly joined to said
pressurized fluid supply conduit and separately joined to said particulate
supply conduit and capable of generating at least one particulate
containing fluid jet stream, the improvement comprising: passing said
particulates through a particulate valve means within said nozzle assembly
which automatically closes a flexible wall particulate supply conduit when
said pressurized fluid supply means is in activated and automatically
opens said flexible wall particulate supply conduit when said pressurized
fluid supply means is activated, said particulate valve means comprising a
valve piston movable within a cylinder substantially parallel to said
flexible wall particulate supply conduit within said nozzle assembly and
having a side recess facing said flexible wall particulate supply conduit;
a valve ball sized to fit adjacent said piston away from said side recess
forcing said flexible particulate supply conduit closed when said valve
piston is moved to a first position by force of a bias spring force
against a first end of said piston, and sized to fit within said piston
side recess when said valve piston is moved to a second position by force
against an opposite second end of said piston caused by said pressurized
fluid thereby opening said flexible particulate supply conduit for supply
of particulates to said particulate containing fluid jet stream, said
pressurized fluid force caused by passage of said pressurized fluid from
said fluid supply conduit through fluid passage means within said nozzle
assembly. |
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Claims |
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Description |
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BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to a process and apparatus for generating high
velocity particulate containing fluid jets which are suitable for making
notches in blast holes to control fracture formation during the detonation
of explosives.
2. Description of the Prior Art
Blasting with explosives is utilized in mining, tunneling, excavation,
demolishing operations, and the like, to remove hard, generally
impenetrable materials such as ice, rock, minerals, concrete, and the
like. In blasting operations, blast holes are drilled into the hard
material, generally with a percussive tool or a drill, and the holes are
filled with explosives. If a large volume of material is to be removed, a
series of blast holes must be drilled in a prescribed pattern to control
the pattern of explosion and material removal. Proper spacing and
arrangement of blast holes depends upon the properties of the hard
material being removed and the amount and type of explosives used.
It is highly desirable to control fracture formation during detonation of
explosives so as to control the explosion and removal pattern by linking
the blast holes. One common method of controlling fracture formation is to
make wedge-shaped notches along a blast hole in the direction of the
desired fracture formation. Notching blast holes in hard materials, such
as rock, minerals and concrete is, however, very difficult. Carbide or
diamond studded cutting wheel tools, saws, and drills have been devised
for notching blast holes, but these tools have recognized limitations,
such as rapid wear of cutting edges, expense to manufacture and operate,
slow, noisy, dusty and fatiguing operation, and excessive fragility for
use in most blasting environments.
High velocity water jets generated at pressures of up to 60,000 psi are
used industrially to cut various materials, such as paper products,
leather, polymers, plastics, textiles and asbestos products. Utilization
of high velocity water jets for cutting operations is gaining popularity
because of its many inherent advantages, including absence of tool contact
and wear, heat and dust generation, and high speed and quality of cuts.
U.S. Pat. No. 4,478,368, which is incorporated herein by reference in its
entirety, describes high pressure water jet apparatus, applications and
technology. Since high velocity water jets can be generated utilizing
relatively small nozzles, the water jet apparatus can be inserted directly
into a blast hole for notching the rock. In general, however, the
application of high velocity water jets to cut hard materials such as rock
and concrete has been unsatisfactory, since the water jets tend to cause
spalling and fracturing of hard materials, rather than cutting the
material cleanly.
Abrasive particles propelled by compressed air have been used to cut many
hard materials. This method can be quite effective when the abrasive
particles are accelerated to high velocity and ejected through a suitable
nozzle. However, the difficulty in containing the particles and dust
during cutting operations prohibits its use in large scale material
cutting. Currently, air-propelled abrasive powders are used for deburring
metals and for surface preparation of materials where a hood or an
enclosure can be employed to contain the dust. A wide variety of abrasive
powders, such as silicon carbide, aluminum oxide, garnet, glass beads and
silica sand are used for such applications.
The combination of solid particulates with a high pressure fluid jet has
been utilized for several purposes. For example, U.S. Pat. No. 2,810,396
teaches solid particles in an air or steam injector as an attrition impact
pulverizer; U.S. Pat. No. 3,424,386 teaches mixing of granular solids with
a liquid for use in sandblasting; U.S. Pat. Nos. 3,972,150 and 3,994,097
teach water jets having particulate abrasives for cleaning with water
pressures under 5000 psi; U.S. Pat. No. 4,080,762 teaches a fluid and
abrasive jet for paint removal with fluid pressures up to 30,000 psi; and
U.S. Pat. No. 4,125,969 teaches a wet abrasion blast cleaning apparatus
and method utilizing soluble abrasive materials. U.S. Pat. No. 4,449,332
teaches a nozzle holder for dispensing a water jet containing particulate
abrasive material which may be used for cutting or cleaning applications.
The nozzle assembly is capable of withstanding high liquid pressures of
between about 10,000 to about 50,000 psi.
U.S. Pat. No. 4,478,368 teaches a high velocity particulate containing
fluid jet apparatus and process providing improved fluid jet quality by
utilizing multiple fluid jets and flow shaping construction. This patent
also teaches the supply of solid particulates in a foam for mixture with
the fluid jet stream to minimize energy loss of the fluid jet stream and
provide better control of the introduction of solid particulates into the
fluid stream. Very hard materials, such as concrete, rock, glass and
metals, may be cut using fluid jets containing abrasive particulates which
have been generated at moderate fluid pressures and at high fluid
pressures of up to 60,000 psi. Gene G. Yie, "Cutting Hard Rock with
Abrasive-Entrained Waterjet at Moderate Pressures", paper presented at 2d
U.S. WaterJet Symposium, Rolla, Mo., May 26, 1983, for example, described
that glass can be cut into complicated shapes with abrasive fluid jets
when very hard abrasives, such as garnets, are used. Fluid jets containing
abrasive particulates may be utilized to make many different types of
cuts. The kerf produced by a suitable abrasive water jet nozzle may be as
narrow as less than 0.05 inch or as wide as more than 1.0 inch.
In these types of particulate containing fluid jet generators, the factor
which determines the cutting capabilities of the abrasive fluid jet is the
efficiency of the nozzle assembly in accelerating the particulates in the
fluid jet for cutting applications. It is desirable that the velocity of
the abrasive fluid jet as it exits the nozzle is as high as possible, and
that all particulates introduced be accelerated to a very high speed. It
is preferred, in these types of abrasive fluid jet generators, that all
fluid and particulate chamber walls have smooth surfaces to minimize fluid
turbulence. Mixing of abrasive particulates into a highly pressurized,
coherent fluid jet is very difficult to achieve.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide a process and apparatus
for generating high velocity particulate containing fluid jet streams
capable of cutting very hard materials such as ice, concrete, rock and
minerals.
It is another object of the present invention to provide a high velocity
particulate containing fluid jet apparatus which may be inserted into a
blast hole and activated to generate one or more particulate containing
fluid jet streams for making notches in a blast hole.
It is yet another object of the present invention to provide a process and
apparatus for generating particulate containing fluid jet streams
incorporating a particulate passage valve means which permits the free
flow of particulates during operation of the apparatus, and closes the
particulate passage at the nozzle assembly when the apparatus is not
operating.
It is yet another object of the present invention to provide a particulate
passage valve means at the nozzle assembly which responds to changes in
fluid pressure to open and close the particulate passage in a high
velocity particulate containing fluid jet apparatus and process.
It is yet another object of the present invention to provide a blast hole
drilling and notching means utilizing high velocity particulate containing
fluid jet streams which is portable, durable and lightweight, and is
operable in horizontal, vertical, and inclined positions.
It is yet another object of the present invention to provide a blast hole
notching means utilizing high velocity particulate containing fluid jet
streams to control fracture initiation in blast holes for use in numerous
geotechnical applications, such as mining, tunneling, demolishing,
trenching, excavation, construction, and the like.
According to the process and apparatus of the present invention,
pressurized fluid is delivered to a nozzle assembly separately from
particulates, and particulates are introduced into one or a plurality of
pressurized fluid streams to generate one or more high velocity
particulate containing fluid jet streams. The one or more particulate
containing fluid jet streams may be oriented parallel to one another, or
they may be diverging or converging with respect to the central axis of
the nozzle assembly, as is known to the art. The apparatus of the present
invention may be sized for insertion directly into blast holes for making
notches therein and, in a preferred embodiment, is provided with a
particulate passage valve means which operates to close and seal the
particulate passage when the fluid jet apparatus is not in operation and
open the particulate passage as soon as fluid jets are generated. In
another preferred embodiment, the valve means operates in response to
changes in fluid pressure of the pressurized fluid supplied. According to
yet another preferred embodiment, one or more high velocity particulate
containing fluid streams cooperates with a drill tip provided on the
nozzle assembly to provide an apparatus capable of drilling holes in hard
materials such as rock. Blast holes in very hard rock having a compressive
strength in excess of 20,000 psi can be notched to a considerable depth
utilizing particulate containing fluid jet streams generated by moderate
fluid pressures of about 10,000 psi according to the process and apparatus
of the present invention.
BRIEF DESCRIPTION OF THE DRAWINGS
Specific embodiments of the apparatus of the present invention are shown in
the drawings, wherein:
FIG. 1 shows, schematically, an apparatus of the present invention,
including the particulate and fluid supply means;
FIG. 2 shows a partially cut away, partially sectional view of a preferred
arrangement for enclosing and protecting the apparatus of the present
invention;
FIG. 3 shows an enlarged, partially cross-sectional view of one preferred
embodiment suitable for drilling holes and/or for notching holes;
FIG. 4 shows a perspective view of one embodiment of a discontinuity
generator according to the present invention;
FIG. 5 shows a perspective view of another embodiment of a discontinuity
generator according to the present invention;
FIG. 6 shows an enlarged partially cross-sectional view of a nozzle
assembly suitable for generating a plurality of diverging particulate
containing fluid jet streams;
FIG. 7 shows an enlarged partially cross-sectional view of a nozzle
assembly with a particulate passage valve means in closed condition to
seal the particulate passage when the apparatus is not operating;
FIG. 8 shows the nozzle assembly of FIG. 7 with the particulate passage
valve means in open condition due to high fluid pressure to provide
particulate supply for generating a plurality of high velocity particulate
containing fluid jets;
FIG. 9 shows a nozzle assembly similar to that shown in FIG. 8, in which
the particulate passage valve means is activated manually or mechanically
by a valve stem means;
FIG. 10 shows a schematic view of the nozzle assembly of FIG. 3 as it would
operate in a drilling mode;
FIG. 11 shows a blast hole with two opposing notches for controlling
fracture initiation in the direction of the notches; and
FIG. 12 shows a blast hole with a plurality of notches facilitating
controlled explosion and material removal.
DESCRIPTION OF PREFERRED EMBODIMENTS
As shown in FIG. 1, particulates for generating particulate containing
fluid jet streams are stored in particulate tank 10, metered through flow
controller 11, and conveyed through particulate hose 12 to tube/hose
adapter 15. A wide range of solid particulates may be used in the process
and apparatus of this invention, most suitably those having average
diameters from about 2 microns to about 1200 microns, and preferably from
about 10 microns to about 200 microns. Especially suitable particulates
for use in this invention include abrasives such as silicon carbide,
aluminum oxide, garnet, silica sand, metallic slag, glass beads, and the
like.
Particulates for mixture with a fluid jet stream may be provided in a foam
or a slurry form, or in a gaseous stream, as is known to the art. The
transport of solid particulates in foam is advantageous since the foam
containing particulates can be readily released under pressure or pumped
through tubing over a long distance without settling of the particulates
and with reduced wear and abrasion to the particulate tubing. Supply of
particulates in a foam also permits control of the rate of particulate
introduction into fluid jet streams and provides uniform distribution of
particulates in the particulate supply means. In a preferred embodiment,
flow controller 11 is controlled electronically, pneumatically, or
hydraulically so that flow controller 11 releases particulates only when
the pressurized fluid supply means is operating to provide fluid jet
streams to the apparatus as indicated schematically by dashed lines in
FIG. 1. Simple gravity feed arrangements are also suitable.
Fluid for generating particulate containing fluid jet streams is
pressurized in high pressure pump 13 and conveyed to tube/hose adapter 15
through high pressure hose 14. The process and apparatus of this invention
may be used for mixing particulates with a fluid stream of liquid or gas
for any desired purpose. Water and aqueous solutions are particularly
suitable fluids for use in notching blast holes. Fluid pressures of from
about 100 to about 60,000 psi are desired for use in the present
invention. Suitable pumps for generating pressurized fluid streams and
tube and hose materials capable of withstanding fluid pressures of from
about 100 to about 60,000 psi are known to the art. Particulate hose 12
and high pressure fluid hose 14 are preferably flexible, and may be
provided in any length required for specific applications.
The portion of the particulate containing fluid jet apparatus including and
below tube/hose adapter 15 as shown in FIG. 1, is preferably relatively
rigid and may be provided with braces 18 to facilitate insertion of this
portion of the apparatus into a blast hole or the like, for making notches
in the blast hole. Tube/hose adapter 15 is generally situated outside the
blast hole, and therefore may be larger in diameter than blast holes which
are generally about 2 inches in diameter and less. Tube/hose adapter 15
may be provided with a handle to facilitate manual insertion and removal
of the apparatus from blast holes, or it may be mounted on a track to
provide controlled or mechanized movement, if desired.
In a preferred embodiment shown in FIG. 2, the apparatus is provided with a
rigid cover tube 19, rigidly connected at one end to nozzle assembly 20,
such as by welding or screw engagement, and connected at its other end to
fluid manifold 21 by means of cover tube collar 23. Cover tube 19
preferably comprises high strength steel or stainless steel. Fluid
manifold 21 provides division of a high pressure fluid stream into two or
more high pressure fluid tubes 16. Utilization of cover tube 19, fluid
manifold 21 and cover tube collar 23 provides a sealed environment which
is particularly advantageous when a valve means is provided to regulate
the flow of particulates. Braces 18 may be provided to restrain and align
fluid tubes 16 and particulate hose 17 in cover tube 19. Other types of
adapters providing alignment of and securing cover tube 19 are also
suitable.
Particulates are supplied to nozzle assembly 20 through abrasive tube 17,
while pressurized fluid is supplied through high pressure fluid tubes 16.
In the embodiment illustrated in FIGS. 1 and 2, two high pressure fluid
tubes 16 are provided to generate two discrete particulate containing
fluid jet streams 22, but a single high pressure fluid tube 16 may be
utilized to generate multiple particulate containing fluid jet streams as
shown in FIG. 3. Diversion of high pressure fluid and particulates from a
single supply tube or hose to a plurality of fluid jet nozzles 30 may be
accomplished by the provision of suitable channels in nozzle body 36. The
desired length of high pressure fluid tube 16, abrasive tube 17 and cover
tube 19 depends upon the particular application and, frequently, upon the
depth of the blast holes to be notched.
High pressure fluid streams are provided to nozzle assembly 20 separately
from particulates, and nozzle assembly 20 is capable of dispersing
particulates in high velocity fluid jet streams to provide high velocity
particulate containing fluid jet streams. FIG. 1 illustrates an embodiment
in which two discrete divergent particulate containing fluid jet streams
22 are generated, each stream issuing from nozzle assembly 20 at an angle
of about 45.degree. from central axis C of nozzle assembly 20. In
operation, the rigid portion of the apparatus below tube/hose adapter 15
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