GB2336863A

GB2336863A - A method of blasting

Info

Publication number: GB2336863A
Application number: GB9809301A
Authority: GB
Inventors: Alan Hetherington; Leslie Wheatcroft
Original assignee: Individual
Current assignee: Individual
Priority date: 1998-05-01
Filing date: 1998-05-01
Publication date: 1999-11-03
Anticipated expiration: 2018-05-01
Also published as: GB2336863B; GB9809301D0

Abstract

A method of blasting comprises introducing a gelling agent into a blast hole 4 containing water 5 to create a solid plug 6, and then introducing an explosive onto the plug.

Description

2336863 An Aid to Charging Wet Blast figles

Field of Iny_gntion

This Invention (henceforth referred to as product) relates to the solidification of water In quarry or opencast blast holes.

Background to Inventiol]

A common problem in quarrying Is the presence of water in blast holes. The majority of blast holes in Britain today are drilled to a depth of 10 to 30 metres.. with a diameter between 100 and 160 mm (Fig 1). The main explosve type is Ammonium Nitrate Prills mixed with fuel oil (A.N.F.O.). This type of explosive is destroyed on contact with water.

Summa This product is a means of creating a 'dry blast hole'. A chemical powder As sealed in a special bag, which when introduced to water,, dissolves,, releasing the powder which reacts with the water to create a gel. The gel may form a dry,. waterproof cap. or alternatively,, with a greater powder to water ratio, may solidify the full amount of water. Either of these situations is suitable for charging with A.N.F.O. explosive with no ill effects.

Page 2 Brief ftscription of Drawing Figure 1 shows a typical blast hole In a hard rock quarry. The main features shown are the quarry top, floor, rock face and the drifted blast hole. It is not drawn to scale.

Detailg.d Description of illustrated Embodiment

Figure 1 shows the quarry top 1. quarry floor 2 and the rock face 3. Also shown As the position and length of the drilled blast hole 4,r In relation to these three features. The rock face may be 20 metres In heightr so the drilled blast hole would be required to reach a depth of 21 metres. For our example., there Is 2 metres of water 5 In the bottom of the hole. The product is dropped freefall down the hole 4 where It meets the water 5 and creates a solid plug 6 as explained earlier In the summary. The bottom of the hole is now dry and can be charged with A.N.F. O. to the desired distance from the quarry top 1. The remainder of the hole is felled with stemming 7 which consists of stone chippings and is a standard practice In the extractive Industries,, to control and contain the explosive charge on detonation.

Page 3

Claims

ClaiMg

1. A product which will turn a liquid (i.e. water) into a solid (gel) within the confines of a blast hole.

2. A product as In claim 1 whereby the gelling agent is a superabsorbent chemical compound.

3. A product as In claims 1 and 2 whereby the gelling agent is delivered to the water present in a blast hole by means of a dissolvable bag.

4. A product as In claim 3 which enables the gelling agent to negotiate the full length of a blast hole before being introduced to the water present.

5. A product as In claim 3 which negates the possibility of introducing the gelling agent to moisture elsewhere An the blast hole (i.e. sidewalls).

6. A product whose constituents separate,, or together,, are environmentally safe,, hazard free and toxin free.

1..: zi Ll- Amendments to the claims have been filed as follows CLAIM A method of blasting comprising introducing a gelling agent into a blast hole containing water to convert the water to a gel, and then introducing an explosive onto the gelled water in the blast hole.