US3760727A

US3760727A - Blast-hole liner

Info

Publication number: US3760727A
Application number: US00149565A
Authority: US
Inventors: R Callister; R Langer
Original assignee: Masabi Jobbers Inc
Current assignee: FREDRIKSON BYRON COLBORN BISBEE & HANSEN PA A MINNESOTA PROFESSIOAL ASSOCIATION; Viking Explosives and Supply Inc
Priority date: 1971-06-03
Filing date: 1971-06-03
Publication date: 1973-09-25
Anticipated expiration: 1990-09-25
Also published as: CA949388A; AU4275872A

Abstract

Blast-hole liner which includes a flexible, water-proof tube member closed at one end and a pouch member depending from the closed end of the tube member. The pouch member is provided with an opening spaced from the distal end thereof to permit weighting material to be inserted into the pouch distally of the opening.

Description

[ Sept. 25, W73

United States Patent 1 1 Callister et al.

[ 4] BLAST-HOLE LINER FOREIGN PATENTS OR APPLICATIONS Inventors: Richard Callister; Robert 667,051 7/1963 102/24 Langer, both of Virginia City, Minn.

[73] Assignee: Masabi Jobbers Inc Virg inia City, Primary Examiner-Verlin R. Pendegrass Attorney-James R. Haller Minn.

22 Filed: June3',"i"9'7i"" 21 Appl.No.: 149,565

[57] ABSTRACT Blast-hole liner which includes a flexible, water-proof tube member closed at one end and a pouch member depending from the closed end of the tube member. The pouch member is provided with an opening spaced from the distal end thereof to permit weighting material .C n r "8 e mus s xm UIF

Refere Cit d to be inserted into the pouch distally of the opening. UNITED STATES PATENTS 10 Claims, 5 Drawing Figures 3,106,159 Abramson............................. 102/30 BLAST-HOLE LINER The present invention relates to the preparation of a blast-hole to receive an explosive charge, and more particularly relates to a flexible blast-hole liner.

In the mining industry, particularly in open pit or surface mining wherein the desired mineral lies at or slightly below ground level,explosive charges are employed to break up the mineral into small pieces so that it may be easily gathered up. In this process, a plurality of blast holes ranging in diameter from several inches to over a foot are formed in the earth by known means, and explosive charges are inserted therein, together with primers to detonate the charges. Of the many explosive materials which may be utilized, ammonium nitrate, (preferably containing a small amount of fuel oil and popularly referred to as ANFO) has enjoyed wide usage. Ammonium nitrate, however, is soluble in water, and accordingly great care must be used when this explosive is used in blast holes wherein water seepage into the hole may occur. Although wet ammonium nitrate will explode, the explosive quality of such material is far from satisfactory.

Efforts to protect the explosive charge in a blast hole from moisture have involved the use of various liner materials, as represented by US. Pat. Nos. 2,745,346; 3,188,906 and 3,064,572. In general, plastic tubing having a weighted lower end is lowered into a blast hole and then filled for at least a portion of its length with explosive. Compressed gas may be used to first expand the tubing into contact'with the hole walls, if desired. To avoid transporting weighting material to the blast hole site a blast hole liner is used which is normally sealed shut a short distance from its lower end to leave an open-ended lower section of tubing which may be filled with rocks or other weighting material at the blast site and then tied shut to keep the weighting material from escaping when the tubing is lowered into the blast-hole. Blast-hole liners of this general type are de picted in US. Pat. Nos. 2,745,346 and 3,064,572. The necessities of manually up-ending the open lower end of such tubing for the insertion of rocks and then tying shut the end of the tubing are bothersome and timeconsuming chores, particularly in view of the fact that many hundreds of blast-holes may often be prepared for simultaneous detonation. Avoidance of these steps, particularly the tying step, is accordingly to be desired. Further, it is desired that a blast-hole liner be capable of flat storage, as in roll form, and that undue twisting of the liner be avoided as the liner is drawn from a reel into the blast hole by its weighted end.

It is an object of the present invention to provide a blast-hole liner which may be easily weighted with weighting material without up-ending or tying operatrons.

It is another object of the invention to provide a blast-hole liner which may be easily weighted and which is capable of flat storage on a reel.

It is yet a further object of the invention to provide a flat-storable blast-hole liner which may be easily weighted and which further avoids undue twisting when lowered into a blast-hole.

These and other objects are provided by the blasthole liner of the invention which, briefly described, comprises a. a section of flexible, waterproof tubing having an open end for admission of an explosive charge and a watertight closed end, and

b. a pouch member having proximal and distal ends and which is joined at its proximal end to the closed end of said tubing, said pouch member having an opening therein spaced from said distal end to permit insertion of weighting material into the pouch member distally of said opening.

Referring to the drawing,

FIG. l is a side view of an end section of a flattened blast-hole liner of the invention;

FlIG. 2 is an enlarged edge view, in cross-section of the blast-hole liner depicted in FIG. l, with lowered pouch member;

FIG. 3 is a perspective view of the blast-hole liner depicted in FIG. 2 wherein the pouch member contains weighting material;

FIG. 4 is a side view of an end section of a flattened blast-hole liner of the invention including a protective sheath;

FIG. 5 is an enlarged edge view, in cross-section, of the blast-hole liner depicted in F IG. 4i.

Referring to the drawing, a flattened section of water-proof, flexible tubing lit) having an open upper end (not shown) for admission of an explosive charge is provided with a water-tight, closed lower end 12 by means of transverse, water-proof seal M. Flattened, flexible pouch member 16, having proximal and distal ends W and 20 is joined at its proximal end 11% to the sealed end Il2 of the tubing lit) by seal 22. Pouch member 16 is preferably tapered along at least a portion of its length (distal end 26% being narrower than proximal end 18) to permit easy insertion of the pouch member into a blast-hole, as will be discussed more fully below. The pouch member is provided with a transverse opening 24 which is spaced from the distal end 24) of the pouch so that rocks 26 or other weighting material may be inserted through the opening into the pouch distally of (i.e., below) the opening 24. As such, the rocks are held by gravity into that portion of the pouch which is below (i.e., distal of) opening 2d so that the rocks do not fall out when the weighted pouch draws the blasthole liner into a blast-hole. Preferably, opening 2d is a transverse cut or slit in the wall of pouch 116 so that the opening tends to close when the weight of the weighting material is removed (as when the pouch reaches the bottom of the blast hole), thus providing secure retention of the weighting material in the pouch.

The proximal end 18 of the flattened, flexible pouch member is preferably joined transversely across at least a portion of its width to the sealed end 12 of the flattened tubing to permit the pouch member to facingly engage the tubing during storage in roll or coil form on a reel. The pouch member is thus permitted to assume a plane which is parallel with the plane defined by the flattened tubing.

As will be evident from FIGS. 11 and 2, the blast-hole liner there depicted may readily be manufactured from a single length of flattened, flexible, tubular, heatsealable material by (l) doubling the lower end portion of the tubing baclc upon itself, to form crease or bend 3t), (2) sealing the doubled-back section slightly above crease 3th to the main, decending portion of the tubing by means of a transverse heat seal shown as M and 22 (which also provides a water-proof seal across the lower end of the decending tubing), (3) tapering (as by knife trimming) that portion of the doubled-back section which extends beyond heat seal M and 22 so that the width of the terminal end of the doubled-back section is less than the width of this section at heat-seal l4 and 22, (4) heat-sealing the open end of the doubledback section by means of

heat seals

32, 34 and 36 to form the doubled-back section into a closed pouch, and (5) transversely slitting one wall of the thus-formed pouch along a portion of its width to provide an opening 24 therein spaced from terminal (distal) end 20 of the pouch. This method of manufacture lends itself readily to the use of common heat-sealing equipment adapted for sealing the edges of heat-scalable material.

Referring now to FIGS. 4 and 5, the blast-hole liner of the invention is preferably provided with a flattened, flexible, protective sheath member 40 which sheaths the tubing for a portion of its length adjacent its end 12. Sheath member 40 is joined to the sealed end 12 of the tubing by seal 42 in FIGS. 4 and 5, and extends for a short distance beyond this seal. Seal 42 also seals the end 12 with a water-tight transverse seal. F lattened pouch member 16', having proximal and distal ends 18' and 20, is joined by seal 22' at its proximal end 18 to that portion of the sheath member which extends beyond seal 42. The separately-formed pouch member 16 is tapered as described above along at least a portion of its length for easy insertion into a blast-hole. The sheath member 40 serves to protect the lower portion of the blast-hole liner from abrasions which might otherwise be inflicted by the rough, inner walls of a blast-hole during insertion of the liner therein.

The liner depicted in FIGS. 4 and 5 may be manufactured by a method similar to that previously described with reference to the liner of FIGS. 1 and 2. Tubing l0 and sheath member 40 are first joined by transverse heat-seal 42. Pouch member 16, duly tapered and sealed as described above, is heat-sealed at 22 to the sheath member.

In use, the blast-hole liner of the invention is conveniently provided at the blast-hole site in flat, roll form, preferably on a reel. The diameter of the liner is preferably selected to be slightly larger than the diameter of the blast-hole so that the liner will expand to engage the walls of irregularly drilled or pierced holes as explosive is poured into the liner.

The liners of the invention may be provided in any convenient size. A typical liner made of 7.0 mil polyethylene may have a diameter of 12 inches and may be 50 feet in length.

A short length of the liner is unreeled to expose the pouch member which is then filled with a convenient weighting material such as rocks at the blast site. After preferably emptying the blast-hole of any water, the weighted pouch is permitted to draw the liner into the hole. When filled with rocks, the flexible pouch member tends to bulge as shown in FIG. 3, and assumes a rounded cross-section which tends to center the leading end of the liner in the hole. It is noteworthy that the blast-hole liners of the invention exhibit very little if any twisting when inserted in a blast-hole, and it is believed that this feature is due primarily to the tapered, rounded, weighted pouch members which are employed.

When the liner has been fully inserted into the blast hole, explosive (e.g., prills of ANFO) are poured into the liner, a suitable detonator is incorporated in the explosive and is fused with common fusing (e.g., Prima cord), the remaining liner is twisted to reduce its diameter, and the remainder of the hole not occupied by explosive (usually the top few feet) is filled with 4 crushed rock or other material, as is well known to those skilled in the art. A few feet of liner (with the enclosed fusing) ususally protrudes from the blast-hole.

The liners of the invention may be made from any flexible, water-proof material such as plastics, coated cloth, etc. Blown thermoplastic tubingsuch as polyethylene and polypropylene are preferred. Polyethylene tubing of about 7 mils in thickness has given excellent results and is especially preferred. If heat seals are desired, heat-sealable material must be used; however, other flexible materials may also yield acceptable results. In this respect, it will be understood that the seals and manufacturing methods referred to above with reference to the drawing need not be heat seals but may instead be adhesive or other seals. Heat seals and heatsealable materials are preferred. The pouch members, of course, need not be waterproof and hence may be of any strong, flexible sheet material.

We claim:

1. A flat-storable blast-hole liner which comprises:

a. a flattened section of flexible, water-proof tubing having an open end to admit an explosive charge and a water-tight, transversely sealed closed end, and a flexible, flattened pouch member which has proximal and distal ends and which is sealed at its proximal end transversely across its width and there joined to the closed end of said tubing by a waterproof seal to permit said pouch member to assume a plane which is parallel to the plane defined by said flattened section of tubing, said pouch member having an opening therein spaced from said distal end to permit the insertion of weighting material into the pouch member distally of said opening, at least two plies separating the explosive from the weighting material when the tubing and pouch member are respectively charged with explosive and weighting material.

. A flat-storable blast-hole liner comprising a section of flattened, flexible water-proof tubing, one end of said tubing being open to admit an explosive charge, and the other end of said tubing being closed by a water-proof seal extending transversely of said tubing, and

b. a flattened, flexible pouch member having proximal and distal ends, the proximal end of which is sealed along its width by a transverse, water-proof seal and there sealed to the sealed end of said tubing to permit said flattened pouch member to facingly engage said flattened tubing during storage in roll form, said pouch member having an opening therein spaced from said distal end to permit the insertion of weighting material into said pouch member distally of said opening, at least two plies separating the explosive from the weighting material when the tubing and pouch member are respectively charged with explosive and weighting material.

3. The blast-hole liner according to claim 2 which includes a second flattened, flexible, protective sheath member which sheaths said tubing for a portion of its length adjacent the sealed end thereof, said sheath member being joined by a transverse, water-proof seal, to the sealed end of said tubing; said pouch member being transversely sealed at its proximal end to the sealed end of said sheath member.

4. The blast-hole liner according to claim 2 wherein the distal end of said pouch member is narrower in width than the proximal end thereof.

5. A flat-storable blast-hole liner comprising a. a section of flattened, flexible, water-proof tubing,

one end of said tubing being open to admit an explosive charge, and the other end of said tubing being closed by a water-proof heat seal extending transversely of said tubing, and

b. a flattened, flexible pouch member having proximal and distal ends, said proximal end being heat sealed transversely along its width and there heat sealed to the sealed end of said tubing to permit said flattened pouch member to facingly engage said flattened tubing contiguous its sealed end during storage in roll form, said pouch member having an opening therein spaced from said distal end to permit the insertion of weighting material into said pouch member distally of said opening, at least two plies separating the explosive from the weighting material when the tubing and pouch member are respectively charged with explosive and weighting material.

6. A flat-storable blast-hole liner comprising a. a section of flattened, flexible, water-proof tubing, one end of which is open to admit an explosive charge, and the other end of which is closed by a water-proof heat-seal extending transversely of said tubing,

b. a flattened, flexible, protective sheath member sheathing said tubing for a portion of its length adjacent the sealed end of said tubing, said sheath member being transversely heat-sealed to the sealed end of said tubing; an

e. a flattened, flexible pouch member having proximal and distal ends and which is heat-sealed at its proximal end and there transversely heat-sealed to said sealed end of said sheath member to permit said pouch member to facingly engage said flattened tubing contiguous the sealed end of said tubing during storage in roll form, said pouch member having an opening therein spaced from said distal end to permit the insertion of weighting material into said pouch member distally of said opening, at least two plies separating the explosive from the weighting material when tubing and pouch member are respectively charged with explosive and weighting material.

7. The blast-hole liner according to claim 5 wherein the distal end of said pouch member is narrower in width than the proximal end thereof.

8. The blast-hole liner according to claim 6 wherein the distal end of said pouch member is narrower in width than the proximal end thereof.

9. Method of making a flat-storable blast-hole liner comprising a. providing a single length of flattened, flexible, tubular, heat-sealable material having upper and lower ends;

b. doubling the lower end portion of said tubing back upon itself to form a transverse crease;

c. sealing said doubled-back section above said crease to the adjacent descending portion of tubing by means of a transverse heat seal which provides a water-proof seal across the lower end of the descending tubing;

d. tapering the open end of said doubled-back portion of tubing so that the width of the terminal end thereof is less than the width of the doubled-back section at said heat seal;

e. heat-sealing said trimmed open end of said doubled-back section to form said section into a closed pouch; and

f. transversely slitting one wall of said pouch along a portion of its width to provide an opening therein spaced from the terminal end of said pouch.

10. Method for making a flat-storable, blast-hole liner which comprises:

a. providing a length of flattened, flexible, heatsealable tubing having upper and lower opened ends;

b. sheathing said tubing for a portion of its length adjacent said lower end with a flattened, flexible, protective sheath member, which member extends for a short distance below the lower end of said tubing;

0. sealing said sheath member to the lower end of said tubing by means of a transverse heat seal which provides a water-proof transverse seal across said lower end of said tubing;

d. providing a flattened, flexible pouch member having a proximal end and a tapered, sealed distal end, said pouch member having a transverse slit in one wall thereof along a portion of its width to provide an opening therein spaced from said distal end;

e. orienting said pouch member to lie flat against the lower portion of said sheath member, the proximal end of said pouch member being adjacent the lower end of said sheath member; and

f. heat sealing said pouch member to said sheath member by means of a transverse heat seal adjacent their adjacent ends.

UNITED STATES I PATENT OFFICE CERTIFICATE OF CORRECTION Pat 3 .760 .727 Dated September 25. 1973 Inventor) Richard M. Callister & Robert J. Langer It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

In the title page:

The address of the inventors and assignee should be-Virginia, Minnesota-;

The name of the assignee should be Mesabi Jobbers, Inc.-.

In column 5, line 34, "an" should be replaced with and--.

Signed and sealed this 29th day of January 197M..-

(SEAL) Attest:

EDWARD M. FLETCHER,JR. RENE D. TEGTMEYER Attesting Officer v Acting Commissioner of Patents -ORM PO-10 0 (10- 6 9I I I v uscoMM-Dc scan-ps9 k I Y GOVERNMENT PRINTING OFFICE; 1969 0-366-33

Claims

1. A flat-storable blast-hole liner which comprises: a. a flattened section of flexible, water-proof tubing having an open end to admit an explosive charge and a water-tight, transversely sealed closed end, and a flexible, flattened pouch member which has proximal and distal ends and which is sealed at its proximal end transversely across its width and there joined to the closed end of said tubing by a waterproof seal to permit said pouch member to assume a plane which is parallel to the plane defined by said flattened section of tubing, said pouch member having an opening therein spaced from said distal end to permit the insertion of weighting material into the pouch member distally of said opening, at least two plies separating the explosive from the weighting material when the tubing and pouch member are respectively charged with explosive and weighting material.

2. A flat-storable blast-hole liner comprising a. a section of flattened, flexible water-proof tubing, one end of said tubing being open to admit an explosive charge, and the other end of said tubing being closed by a water-proof seal extending transversely of said tubing, and b. a flattened, flexible pouch member having proximal and distal ends, the proximal end of which is sealed along its width by a transverse, water-proof seal and there sealed to the sealed end of said tubing to permit said flattened pouch member to facingly engage said flattened tubing during storage in roll form, said pouch member having an opening therein spaced from said distal end to permit the insertion of weighting material into said pouch member distally of said opening, at least two plies separating the explosive from the weighting material when the tubing and pouch member are respectively charged with explosive and weighting material.

5. A flat-storable blast-hole liner comprising a. a section of flattened, flexible, water-proof tubing, one end of said tubing being open to admit an explosive charge, and the other end of said tubing being closed by a water-proof heat seal extending transversely of said tubing, and b. a flattened, flexible pouch member having proximal and distal ends, said proximal end being heat sealed transversely along its width and there heat sealed to the sealed end of said tubing to permit said flattened pouch member to facingly engage said flattened tubing contiguous its sealed end during storage in roll form, said pouch member having an opening therein spaced from said distal end to permit the insertion of weighting material into said pouch member distally of said opening, at least two plies separating the explosive from the weighting material when the tubing and pouch member are respectively charged with explosive and weighting material.

6. A flat-storable blast-hole liner comprising a. a section of flattened, flexible, water-proof tubing, one end of which is open to admit an explosive charge, and the other end of which is closed by a water-proof heat-seal extending transversely of said tubing, b. a flattened, flexible, protective sheath member sheathing said tubing for a portion of its length adjacent the sealed end of said tubing, said sheath member being transversely heat-sealed to the sealed end of said tubIng; an c. a flattened, flexible pouch member having proximal and distal ends and which is heat-sealed at its proximal end and there transversely heat-sealed to said sealed end of said sheath member to permit said pouch member to facingly engage said flattened tubing contiguous the sealed end of said tubing during storage in roll form, said pouch member having an opening therein spaced from said distal end to permit the insertion of weighting material into said pouch member distally of said opening, at least two plies separating the explosive from the weighting material when tubing and pouch member are respectively charged with explosive and weighting material.

9. Method of making a flat-storable blast-hole liner comprising a. providing a single length of flattened, flexible, tubular, heat-sealable material having upper and lower ends; b. doubling the lower end portion of said tubing back upon itself to form a transverse crease; c. sealing said doubled-back section above said crease to the adjacent descending portion of tubing by means of a transverse heat seal which provides a water-proof seal across the lower end of the descending tubing; d. tapering the open end of said doubled-back portion of tubing so that the width of the terminal end thereof is less than the width of the doubled-back section at said heat seal; e. heat-sealing said trimmed open end of said doubled-back section to form said section into a closed pouch; and f. transversely slitting one wall of said pouch along a portion of its width to provide an opening therein spaced from the terminal end of said pouch.

10. Method for making a flat-storable, blast-hole liner which comprises: a. providing a length of flattened, flexible, heat-sealable tubing having upper and lower opened ends; b. sheathing said tubing for a portion of its length adjacent said lower end with a flattened, flexible, protective sheath member, which member extends for a short distance below the lower end of said tubing; c. sealing said sheath member to the lower end of said tubing by means of a transverse heat seal which provides a water-proof transverse seal across said lower end of said tubing; d. providing a flattened, flexible pouch member having a proximal end and a tapered, sealed distal end, said pouch member having a transverse slit in one wall thereof along a portion of its width to provide an opening therein spaced from said distal end; e. orienting said pouch member to lie flat against the lower portion of said sheath member, the proximal end of said pouch member being adjacent the lower end of said sheath member; and f. heat sealing said pouch member to said sheath member by means of a transverse heat seal adjacent their adjacent ends.