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GB2099117A - Stemming shot holes - Google Patents

Stemming shot holes Download PDF

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Publication number
GB2099117A
GB2099117A GB8213273A GB8213273A GB2099117A GB 2099117 A GB2099117 A GB 2099117A GB 8213273 A GB8213273 A GB 8213273A GB 8213273 A GB8213273 A GB 8213273A GB 2099117 A GB2099117 A GB 2099117A
Authority
GB
United Kingdom
Prior art keywords
stemming
ampoule
water
composition
paste
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Granted
Application number
GB8213273A
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GB2099117B (en
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Unilever PLC
Original Assignee
Unilever PLC
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Unilever PLC filed Critical Unilever PLC
Publication of GB2099117A publication Critical patent/GB2099117A/en
Application granted granted Critical
Publication of GB2099117B publication Critical patent/GB2099117B/en
Expired legal-status Critical Current

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Classifications

    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F42AMMUNITION; BLASTING
    • F42DBLASTING
    • F42D1/00Blasting methods or apparatus, e.g. loading or tamping
    • F42D1/08Tamping methods; Methods for loading boreholes with explosives; Apparatus therefor
    • F42D1/24Tamping methods; Methods for loading boreholes with explosives; Apparatus therefor characterised by the tamping material
    • F42D1/28Tamping with gelling agents
    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F42AMMUNITION; BLASTING
    • F42DBLASTING
    • F42D1/00Blasting methods or apparatus, e.g. loading or tamping
    • F42D1/08Tamping methods; Methods for loading boreholes with explosives; Apparatus therefor
    • F42D1/20Tamping cartridges, i.e. cartridges containing tamping material

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  • Life Sciences & Earth Sciences (AREA)
  • General Life Sciences & Earth Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • General Engineering & Computer Science (AREA)
  • Chemical & Material Sciences (AREA)
  • Dispersion Chemistry (AREA)
  • Medical Preparation Storing Or Oral Administration Devices (AREA)

Abstract

A method of stemming shot holes, in which the transport of water is largely eliminated whilst preserving effective standards of tamping, involves the use of a stemming ampoule containing a gel-forming stemming composition and having a sealable filling aperture (5), the ampoule being filled with water outside the shot hole, the final paste stemming material being produced before the ampoule is introduced into the shot hole. The composition may be present as tablets, granules or flakes, and may be present as a reservoir attached to the inside wall of the ampoule. A tear-off strip may be provided and removed to permit the paste to exude.

Description

SPECIFICATION Method and ampoule for tamping shot holes with paste stemming This invention relates to a method of stemming shot holes in which an explosive charge in a shot hole is stemmed by inserting in the shot hole one or more stemming ampoules containing a watercontaining paste or gel and a stemming ampoule for carrying out the method.
The invention relates particularly to shot stemming as applicable in underground blasting and more particularly in coal mining where conditions require special precautions to suppress respirable dusts and to prevent firedamp and coal dust explosions. Unlike clay stemming, water stemming has the advantage that the material itself obviates the aforesaid hazards. However, water can escape from water stemming cartridges if these are even slightly damaged.
Because the empty cartridge has no stemming action, serious difficulties can arise. These difficulties can be avoided by using a paste or gelatinous stemming because the paste properties, notably the viscid nature of the material, cause it to adhere around the stemming cartridge so that the explosive charge cannot become exposed.
Suitable pastes however contain a substantial amount of water to ensure effective stemming, as well as gelling agents which should be without harmful effect particularly on health. Suitable materials are for example carboxymethylcellulose optionally used with certain activators or bentonite and alkalis.
It is known to fill shot holes underground by means of a pump with paste prepared above ground. However this procedure is disadvantageous for a number of reasons. Flrstly, it is unreliable because it is difficult to verify that the paste has reached the charge and that the charge has been properly stemmed in accordance with regulations. Secondly, a relatively large quantity of paste is required which is undesirable for economic reasons. Furthermore, the need to transport the water component of the paste underground is a particularly negative aspect.
In a further known alternative method paste, in an amount required for one shot hole, is filled into one or more stemming ampoules and the ampouies which are made of polyvinyl chloride or polyethylene, are introduced into the hole after they have been cut at their tips or perforated by some other means. The ampoules are in particular tubular ampoules formed of a flexible plastics film.
The aforesaid ampoules can be relied upon to produce the desired stemming effect because the paste, or at least that portion of the paste expressed from the ampoule, is released into the shot hole where it comes into intimate contact with surface irregularities and/or penetrates any cracks in the shot hole.
The aforesaid paste stemming cartridges have to be made above ground mainly because for economic reasons the mixing and filling of the tamping materials normally requires plant and equipment which is only justified by a high volume of production not normally required at individual mining sites. This necessitates the distribution of filled ampoules from a manufacturing centre to the individual mining sites thus incurring high transport and storage costs because of the weight and volume of the ampoules. Because the paste can contain up to 90% water, considerable amounts of stemming have to be transported over long distances, making this procedure economically unattractive, because of the water transportation aspect.
Moreover, water of suitable quality is generally available in sufficient quantity directly underground.
In the case of water stemming it is already known (from German Patent Specification No 1 066 929) to use preformed water stemming ampoules having sealed smooth tips and to fill these with pressurised water underground and outside the shot hole, the seal the ampoules and to use said ampoules to tamp shot holes. In the case of paste that is suitable for use as stemming, its properties and the difficult conditions underground however mean that the paste cannot be filled underground into empty cartridges or ampoules.
It is the aim of the invention to obtain economic shot stemming with paste which largely eliminates transportation of water whilst preserving effective standards of tamping.
According to the present invention there is provided a method of stemming shot holes comprising tamping the explosive charge in a shot hole with a water-containing paste stemming material by placing in the shot hole at least one stemming ampoule containing the water-admixed paste, characterised in that the stemming ampoule containing a stemming composition and having a sealable filling aperture is filled with water and outside the shot hole, the final stemming material being produced from the water and the stemming composition inside the sealed ampoule before the ampoule is introduced into the shot hole.
The cartridge or ampoules can be filled with water above ground at the mining site or be delivered underground ready filled with the stemming composition which means that proper filling therewith above ground can be assured.
Underground, only water remains to be added, this presenting no problems because conventional methods can be used. The work involved in producing the stemming ampoule is therefore reduced to mixing or dissolving the stemming composition in water. This can take place automatically inside the sealed ampoule or can be assisted in various ways for example by simply shaking the water-filled ampoule.
To minimise the transportation of water the stemming composition can comprise a substantially water-free dry material which forms a homogeneous gel or paste within the ampoule after filling with water.
The stemming composition can be loosely contained within the ampoule but particularly when the water filling aperture is of the type which is closed by a stopper it can be advantageous for the stemming composition to be located in a reservoir within the ampoule. This minimises the risk of any stemming composition being lost before the ampoule is filled with water.
The reservoir may be such that it can be opened to release the stemming composition or the reservoir can be formed from a material which is soluble in water and is automatically dissolved by the water filling.
According to another aspect of the invention there is provided a stemming ampoule comprising a tube of plastics material having a sealable filling aperture or a self-sealing valve through which the tube can be filled with water, the tube containing a quantity of a stemming composition sufficient to form a gel with the water filling.
The stemming composition can comprise one or more tablets which will dissolve in the water filling to produce a homogeneous paste filling having sufficient strength. Alternatively the stemming composition can be in granular or flake form.
Preferably the stemming composition combines with water to form a homogeneous stemming material with only a minimum of mixing being necessary eg by simply shaking the filled ampoule for a short time. To minimise the time between filling the ampoule with water and the ampoule being ready for use the stemming composition should preferably form a paste-like stemming material and be ready for use within a few minutes of the addition of the water filling.
A suitable stemming composition is a mixture of polyvinyl alcohol and sodium tetraborate.
The particle size of the gel-forming constituents, eg polyvinyl alcohol, affects speed of gel formation: coarser grains gel more slowly. For rapid gel formation a particle size of less than about 200 microns is preferred. In conjunction witfrthis material the preferred borate is sodium tetraborate having a particle size of 400 to 700 microns.
The amount of stemming composition contained within the ampoule is preferably such that afterfilling with water the polyvinyl alcohol concentration is in the range 2.5 to 20.5% by weight and the sodium tetraborate in the range of 1 to 8.5% by weight, ie about 25% to 50% of the amount of polyvinyl alcohol. The particles can be coated with polyethylene glycol to an amount of 6% and possibly 10% to 20% of the weight of polyvinyl alcohol to minimise lump formation.
Other suitable compositions to be contained within the ampoule are mixtures of a borate salt and a borate sensitive galactomannan gum such as guar gum.
The ampoule can be provided with a tear-off strip which has been removed after the stemming material has been formed in the ampoule to form a slit through which the stemming material exudes when the ampoule is subjected to external pressure.
The paste should be of sufficient strength so that when the tear-off strip is removed the paste remains in the ampoule but is caused to exude when subjected to the pressure by a stemming rod after the ampoule has been inserted in a shot hole. After being exuded in this wav the paste should remain in position for a sufficient period of time, about 1 hour is normally sufficient, in order to be effective at the time of blasting.
To minimise the formation of lumps in the stemming material it is conveniently arranged that the stemming composition combines with the added water as rapidly as possible after filling.
This can be assisted by arranging the stemming composition along the length of the ampoule and one method of achieving this is to enclose the stemming composition in a reservoir of water soluble material. The reservoir can extend lengthwise of the ampoule and be secured to the inside wall of the ampoule. Alternatively when the stemming composition is in particulate or flake form the composition may be secured in a distributed manner lengthwise of the ampoule. A means for securing the stemming composition in such a manner is a liquid surfactant coating applied to the inside of the ampoule and to which the composition adheres.
The formation of lumps can also be minimised when the stemming composition is particulate by providing the particles with a water dispersible/water-soluble coating. This enables the particles to be evenly dispersed within the water filling before they hydrate.
The invention will now be described with reference to the accompanying drawings in which Figure 1 is a first embodiment of an ampoule shown in partial longitudinal section; Figure 2 is a view similar to Figure 1 showing a second embodiment of a paste stemming ampoule; Figure 3 is a section on line Ill-Ill of Figure 2; and Figures 4 and 5 are elevation and plan views of a reservoir for containing stemming composition in an ampoule.
All the embodiments of the invention use a conventional water stemming cartridge or ampoule 1 performed to the dimensions of the shot hole. In the examples shown in the drawings, a blown plastics film with a rounded or conical tip 2 is used. This ampoule body is formed of for example polyethylene or PVC. At the end opposite the tip 2 the ampoule has shoulder 3 and a short neck 4 enclosing a filling aperture 5 for water. The filling aperture 5 is closable by means of a stopper 6 provided with a radial bead 7 which co-operates with a radial groove 8 in the neck 4 to form a pressure-tight closure.
The invention is also applicable to other known types of ampoule not illustrated herein, particularly ampoules formed from flat film sealed at one end and provided at the opposite end with a self-sealing lipped valve through which water may be introduced but through which it cannot escape.
In Figure 1 the ampoule 1 contains two tablets 9 and 10 incorporating the substantially waterfree dry stemming composition. The ampoule, which with the exception of the two tablets 9 and 10 is empty, is delivered above ground. Figure 1 shows the ampoule after it has been filled with water to the lever 13. The paste is produced inside the ampoule from the water filling and the stemming composition incorporated in tablets 9 and 10.
The paste can be produced by allowing the tablet to degrade in the water and form a gel.
In the embodiment of the invention as shown in Figure 2, a film tube 15 sealed at the top 12 and bottom 14 is attached to the inside wall 11 for example by welding it to the wall of the ampoule 1. Film tube 15 forms a reservoir containing the dry stemming composition in the form of a powder 16 which has the property of forming a paste stemming material with water.
The reservoir is formed of a material which is easily soluble in water for example a gelatin, so that when water is introduced, the reservoir 15 releases the stemming composition and gelling takes place.
As shown in Figures 4 and 5 the particulate stemming composition can be contained in a film tube 1 7 which is sealed at both ends 18 and 19 to give the appearance of a cushion. Sealing produces a higher internal pressure which facilitates the release of powder and filling with water.
Instead of tablets 9 and 10 dry stemming composition can also be used in the form of flakes or rods or any similar shapes whose passage through the filling aperture 5 when stopper 6 is not in place is relatively difficult.
A paste having the properties required for a stemming material can be produced inside the ampoule from the stemming composition and the water filling. The strength of the paste stemming material can be established in advance eg by measuring with an "instron" penetrometer and the strength can be adjusted by varying the amount of stemming composition contained within the ampoule.
To prevent lumping, the paste stemming material is produced in the ampoule as rapidly as possible. This can be achieved by arranging the stemming composition along the length of the ampoule. Particularly useful in this respect are those of the illustrated embodiments in which the stemming composition is contained in a dissoluble reservoir. However, when the stemming compozition is in granulate form the particles of for example polyvinyl alcohol and sodium tetraborate can be coated in a watersoluble or water-dispersible material for example polyethylene glycol. The particulate envelope material allows the stemming composition to be evenly dispersed in the water before the stemming composition hydrates.
Depending on the ampoule construction, water can be introduced by means of filling nozzle connected to a water line.
In an example 11.5 g of polyvinyl alcohol powder ( < 200 flz particle size, MW 179,000, degree of hydrolysis 88%) was intimately mixed with 4.75 g of sodium tetraborate decahydrate powder and then poured into 1.2 g of molten polyethylene glycol (MW 1,500) which has been melted in a mixing vessel jacketed at 800C with hot water. Mixing was carried out for 1 5 minutes before lowering the jacket temperature to 40 500 C, maintaining the stirring for 5 minutes. The 1 7.45 g of free flowing powder thus produced was placed in a standard size ampoule having a self sealing lip valve and a length of approximately 42 cm and a final diameter of approximately 3 cm. The ampoule was filled with 270 ml of hard tap water and within 3 minutes a firm homogeneous gel was formed within the ampoule.

Claims (14)

Claims
1. A method of stemming shot holes comprising tamping the explosive charge in the shot hole with a water-paste stemming material by placing in the shot hole at least one stemming ampoule containing the water-admixed paste characterised in that the stemming ampoule containing a stamming composition and having a sealable filling aperture is filled with water and outside the shot hole, the final stemming material being produced from the water and the stemming composition inside the sealed ampoule before the ampoule is introduced into the shot hole.
2. A method according to Claim 1 in which the ampoule is filled with water underground.
3. A method according to Claim 2 characterised in that the stemming composition comprises a substantially water-free dry material which forms a homogenous gel or paste within the ampoule after filling with water.
4. A method according to any one of Claims 1 to 3 characterised in that the dry stemming composition present in the ampoule contained in a reservoir from which it is released into the water filling.
5. A method according to one of Claims 1 and 3 characterised in that the reservoir containing the dry stemming composition is dissolved by the water filled into the ampoule.
6. A stemming ampoule for carrying out the method according to any one of Claims 1 to 5 comprising a tube of plastics material having a sealable filling aperture or a self-sealing valve through which the tube can be filled with water, the tube containing a quantity of a stemming composition sufficient to form a gel with the water filling.
7. A stemming ampoule according to Claim 6 characterised in that the sensing composition comprises one or more tablets.
8. A stemming ampoule according to Claim 6 characterised in that the stemming composition is in the form of granulate or of instantised flakes.
9. A stemming ampoule according to any one of Claims 6 to 8 characterised in that it comprises a reservoir for the stemming composition attached in the inside wall of the stemming ampoule.
10. A stemming ampoule according to one of Claims 6 to 9 characterised in that the stemming composition comprises a mixture of borate and gum or resin.
11. A stemming ampoule according to one of Claims 6 to 9 characterised in that the stemming composition comprises a mixture of polyvinyl alcohol and sodium tetraborate.
12. A stemming ampoule according to any one of Claims 6 to 11 having a tear-off strip which can be removed after the stemming material has been formed in the ampoule to form a slit through which the stemming material exudes when the ampoule is subjected to external pressure.
13. A method of stemming shot holes substantially as hereinbefore described with reference to the accompanying drawings.
14. A stemming ampoule substantially as hereinbefore described with reference to Figure 1, or Figures 2 and 3 or Figure 4 of the accompanying drawings.
GB8213273A 1981-05-07 1982-05-07 Stemming shot holes Expired GB2099117B (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
DE19813118034 DE3118034A1 (en) 1981-05-07 1981-05-07 "METHOD AND TRIM CAMP FOR INSULATING DRILL HOLES WITH PASTE SET"

Publications (2)

Publication Number Publication Date
GB2099117A true GB2099117A (en) 1982-12-01
GB2099117B GB2099117B (en) 1985-05-01

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ID=6131656

Family Applications (1)

Application Number Title Priority Date Filing Date
GB8213273A Expired GB2099117B (en) 1981-05-07 1982-05-07 Stemming shot holes

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DE (1) DE3118034A1 (en)
GB (1) GB2099117B (en)

Cited By (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB2186954A (en) * 1986-02-19 1987-08-26 Forrester Thomas Dobson Explosives container
ES2046916A1 (en) * 1991-04-10 1994-02-01 Invest Tecnologica De Equipos Blasting tube for cool seams
AU746434B1 (en) * 2000-11-27 2002-05-02 Bis Industries Limited A method of stemming a blast hole and a blast hole stemming material
EP0951634A4 (en) * 1997-01-10 2002-05-02 Boyd J Wathen Method of breaking slabs and blocks of rock from rock formations and explosive shock transmitting and moderating composition for use therein
WO2004044520A1 (en) * 2002-11-12 2004-05-27 Cintec International Limited A blast-absorbing device
RU2350897C1 (en) * 2007-07-18 2009-03-27 Аркадий Владимирович Дугарцыренов Method for tamping of blast down holes in single blasts in opencast mines
US10030959B2 (en) * 2013-06-17 2018-07-24 Allen Park Blasting systems and methods
CN114264207A (en) * 2021-08-16 2022-04-01 北方工业大学 Automatic stemming plugging device for blast hole and blast hole plugging method

Families Citing this family (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE4135777A1 (en) * 1991-10-30 1993-02-04 Wilhelm Leppak PLug for water bottle - has axially projecting tongue which holds it in bottle neck while bottle is being filled
CN109238048B (en) * 2018-09-10 2021-06-08 兖州中材建设有限公司 Surface limestone mine blasting dust-settling method
CN109238059A (en) * 2018-11-02 2019-01-18 玉溪矿业有限公司 A kind of blast hole stemming device
CN115235309B (en) * 2022-06-24 2023-09-01 东北大学 Self-expansion filling body for blast hole blocking and preparation and construction methods thereof

Family Cites Families (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DD30791A (en) *
NL240221A (en) * 1958-06-16

Cited By (10)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB2186954A (en) * 1986-02-19 1987-08-26 Forrester Thomas Dobson Explosives container
GB2186954B (en) * 1986-02-19 1989-11-08 Forrester Thomas Dobson Explosives containers.
ES2046916A1 (en) * 1991-04-10 1994-02-01 Invest Tecnologica De Equipos Blasting tube for cool seams
EP0951634A4 (en) * 1997-01-10 2002-05-02 Boyd J Wathen Method of breaking slabs and blocks of rock from rock formations and explosive shock transmitting and moderating composition for use therein
AU746434B1 (en) * 2000-11-27 2002-05-02 Bis Industries Limited A method of stemming a blast hole and a blast hole stemming material
WO2004044520A1 (en) * 2002-11-12 2004-05-27 Cintec International Limited A blast-absorbing device
RU2350897C1 (en) * 2007-07-18 2009-03-27 Аркадий Владимирович Дугарцыренов Method for tamping of blast down holes in single blasts in opencast mines
US10030959B2 (en) * 2013-06-17 2018-07-24 Allen Park Blasting systems and methods
CN114264207A (en) * 2021-08-16 2022-04-01 北方工业大学 Automatic stemming plugging device for blast hole and blast hole plugging method
CN114264207B (en) * 2021-08-16 2024-01-09 北方工业大学 Automatic stemming blocking device for blasthole and stemming blocking method

Also Published As

Publication number Publication date
DE3118034A1 (en) 1982-11-25
GB2099117B (en) 1985-05-01

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PCNP Patent ceased through non-payment of renewal fee