AU614388B2 - Method of loading a borehole with explosives - Google Patents

Description

1 S F Ref: 99696 FORM COMMONWEALTH OF AUSTRALIA PATENTS ACT 1952 COMPLETE SPECIFICAiN 48

(ORIGINAL)

FOR OFFICE USE: Class Int Class Complete Specification Lodged: Accepted: Published: Priority: Related Art: Name and Address of Applicant: rt 0 4 0 Mining Services International Corporation Cedar Park 5284 S 320 W Salt Lake City Utah UNITED STATES OF AMERICA Spruson Ferguson, Patent Attorneys Level 33 St Martins Tower, 31 Market Street Sydney, New South Wales, 2000, Australia Address for Service: Complete Specification for the invention entitled: 1 4 Method of Loading a Borehole with Explosivas The following statement is a full description of this invention, including the best method of performing it known to me/us 5845/3 a 0 0 000 2- 00 0 0 0 0 0 00ooo00 oo0000 BACKGROUND OF THE INVENTION 0 0 00o .000 This invention relates to the loading of uulk explosives and blasting 0 o 0 a 0 agents into boreholes. In particular, the invention relates to loading water-filled boreholes with a flowable explosive.

0000 Soo0 5 Various methods' of loading boreholes in mining are well known in the 0o0 art. Granular, dry-blasting agents such as ANFO are commonly augered 0 into the borehole from the top and allowed to fall so as to fill the oo° hole from the bottom. Flowable explosives such as certain Heavy ANFO's can be loaded into dry boreholes in this manner, and can even 10 be augered into the water and allowed to fall through the water to 00 Soo0 fill the hole from the bottom. o0 00 a o n The best and most common way of loading water-proof, flowable explosives from the bottom of the borehole is by the use of a hose.

The end of the hose is initially placed at or nea- the bottom of the hole. When the explosive is pumped through and out of the hose it fills the borehole from the bottom, displacing the water upwards.

The hose is usually withdrawn at a rate which ensures that the end of the hose remains just below the surface of the explosive as the borehole fills.

-3- Under certain circumstances this method of pumping explosives into a borehole, starting at the bottom, has a serious disadvantage. After drilling a hole in rock containing water, the hole often contains some mud at the bottom which is not flushed out by the drill. Depending on the various rocks penetrated by the drill in making the borehole, the mud can have a wide range of consistency and density. Some muds are easily stirred up by action of explosives flowing out of the end of the loading hose. Such muds may be of such density and consistency that they are not easily displaced upwards by the explosive. As a result, explosives pumped to the bottom of boreholes can entrain mud in the lower part of the borehole.

Sometimes, with an adverse combination of exit velocity of explosiva, position of hose in the borehole and viscosity of explosive, even :00 relatively clean water in the bottom of the borehole can become entrained 15 in the explosive.

o t 0000 SUMMARY OF THE INVENTION 0oo o According to the present invention, a method of loading a borehole containing water with a flowable explosive includes the steps of: (a) loading a flexible tubular sock which is substantially non-extendable in an axial direction over the delivery end of a delivery pipe; locating 000:oo the sock in the borehole; delivering the explosive through the pipe 0°0:00 and into the sock; and withdrawing the delivery end of the pipe from the sock as the sock fills with explosive.

0 0 0 DETAILED DESCRIPTION OF THE INVENTION 00' 25 The sock will be filled in situ at the bottom of the hole. In so doing any water or mud in the borehole will be displaced upwards. The sock isolates the explosive from the water or mud.

1404y -4- The sock may be of the same or slightly larger diameter than that of the borehole so that, when filled, it will lock firmly in place in the hole. In this form of the invention, the explosive will generally be delivered under pressure through a flexible hose into the sock.

The sock may also be placed over the end of a rigid or semi-rigid open-ended pipe which is located in the hole, the pipe having a number of openings formed in the wall thereof.

.oo In this form of i-he invention, the explosive may be delivered by gravity into the pipe from where it will flow into the sock, partly through the open bottom and partly through the side :openings.

The sock may be made of any suitable flexible, water-impervious material. It will typically be made of a suitable plastics material such as polyethylene, polypropylene or polyvinyl chloride.

The explosive will be flowable and may be of the fluid Heavy oo ANFO type, the slurry type or the emulsion type.

0 00°° An embodiment of the invention will now be described with reference to the accompanying drawing which illustrates 00 schematically the four stages of loading a borehole with a 0 flowable explosive. Referring to this drawing, a flexible 00 0 S o loading hose 10 has a loose-fitting sleeve 12 made of polyethylene placed over its delivery end 14. The sleeve 12 is closed at its lower end 16 with a strong closure 18 such as a clip to form a sock. The sleeve is held on to the loading hose by means of a weak attachment 20 such as an elastic band close to its other end 22. The loading hose with the sleeve located thereon is then lowered into the borehole 24 so that it is embedded in the mud 26 at the bottom of the hole and in the water 28 above the mud. Explosive 30 is then delivered into the sock through the flexible hose as illustrated by stage 2.

This is continued until stage 3 is reached. It will be noted that as the sock is filled with explosive so the hose is withdrawn. The final stage reached is that illustrated in the fourth stage when the pressure created by the flowable explosive in the sock ruptures the weak attachment and.

continues to fill the hole above the sock. Throughout the 09 .9 loading operation the explosive is isolated from the water and 0 0 mud by means of the sock. The hose is then finally withdrawn 6 0 0 e o q from the hole and the loaded hole is ready for detonation.

0o 0 0 oa 00 0 o o 0 0 00 0 0 0 0 0 0

Claims (10)

1. A method of loading a borehole containing water with a flowable explosive includes the steps of: loading a flexible tubular sock which is substantially non-extendable in an axial direction over the delivery end of a delivery pipe; locating the sock in the borehole; delivering the explosive through the pipe and into the sock; and (d) withdrawing the delivery end of the pipe from the sock as the sock fills with explosive.

2. A method according to claim 1 wherein the delivery pipe is a flexible hose.

3. A method according to claim I wherein the delivery pipe is a rigid or semi-rigid open-ended pipe having a number of openings formed in the wall thereof.

4. A method according to any one of the preceding claims wherein 15 the sock has a diameter the same or slightly larger than that of the borehole.

A method according to any one of the preceding claims wherein the sock is made of a flexible, water-impervious material.

6. A method according to claim 5 wherein the material is a 20 plastics material. S0o o ooo a o 0 00 a 0 o 000 00 00 0 0 o ,ooooo 0 o o o 0 00 a 0 0 10 0 C V c C c e^ c c LMM/1404y i II~~ -7-

7. A method according to claim 6 wherein the plastics material is polyethylene, polypropylene or polyvinyl chloride.

8. A method according to any one of the preceding claims wherein the sock is formed by placing a loose-fitting sleeve over the delivery end of the delivery pipe and closing one end of the t 0 6 z sleeve.

9. S A method according to any one of the preceding claims wherein the sock is held on the delivery end of the delivery hose by means of a weak attachment adapted to rupture and release the sock from the hose when a predetermined amount of explosive has been delivered into the sock.

010. SA method according to claim 1 substantially as hereinbefore 0D 0 t described with reference to the accompanying drawing. 4 a 0 DATED this TWENTY-SIXTH day of JUNE 1989 Mining Services International Corporation a Patent Attorneys for the Applicant S c SPRUSON FERGUSON I