CA1084340A

CA1084340A - Plant for blasting of objects such as rock, concrete, and the like

Info

Publication number: CA1084340A
Application number: CA275,583A
Authority: CA
Inventors: Per H.G. Lithner
Original assignee: Nitro Nobel AB
Current assignee: Nitro Nobel AB
Priority date: 1976-04-06
Filing date: 1977-04-05
Publication date: 1980-08-26
Also published as: NO144783C; FR2347651B1; NL7703699A; FR2347651A1; DE2714279C3; DE2714279A1; BR7702102A; DD131198A5; ZM3077A1; HU176586B; BE853247A; AT359412B; NO771172L; ATA232277A; PT66401B; DK151477A; GB1566071A; NO144783B; FI770958A; RO74263A

Abstract

ABSTRACT OF THE DISCLOSURE
The invention relates to a plant for blasting of ob-jects such as rock, concrete, and the like, where the objects are provided with a number of bore holes containing fuses with blasting caps and explosives such as dynamite, water-gelatine explosives, and the like. The fuse is a low-energy fuse suit-ably consisting of a tube which is coated inside by an explosive or another reactive substance, and the fuse works together with coupling blocks and start-blasting caps. According to the in-vention, each bore hole is provided with a fuse, which in one end is fitted with a blasting cap and in the other end is free, Outside of the bore holes, a number of coupling fuses are ar-ranged, and are fitted either in one end or in both ends with a start-blasting cap with or without time-delay arranged in a coupling unit, for example, in the form of a coupling block made e.g. of plastic. The unit can take one or more fuses in order to transfer to these the initiation when the start-blast-ing cap is initiated. The coupling units are coupled together in the free ends of the fuses in the bore holes and with the free ends to coupling fuses, and a coupling fuse with a free end has this connected to an initiator. This produces an initiating wave through the connected fuse.

Description

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The pre~ent invention refers to a system for blasting of objects such as rock, concrete and the like.
It may concern blasting of pits and foundations, production blasting of ore and dead rock, tunnelling etc in a certain ; material such as rock.
Earlier, in preparinq the blasting boreholes were made in which a detonator with an attach~d fuse or ignit0r was inserted. Then the hole was filled with an explosive such as for instance dynamite or a water-gel explosive, The end or the ends of the fuse or the igniter protruding from within the borehole wera then connected with an initiator, e.g. a blasting machine, when the igniter consisted of an electric igniter.
However, in certain environments and at certain blasting operations electric igniters have been abandoned, because of the fact that these might unintentionally be initiated, for instance, by vagabond currents or induction.
Recently, another type of fuse has been suggested, a so-called lowenergy ; ' .
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fuse, such as ~escribed in the Swedish Patent No. 333,321 for the initiation o~ detonators.
Such fuses are connectecl with a detonator and a flashover element to ~orm units, which can then be connected together to form an initiation system, as described in Canadian Patent No. 985,956.
~- From each borehole charged with said unit a certain length of low-energy fuse protrudes, which is connected with a flashover element consisting of a transmitter cap and a con-necting block. If work takes place round boreholes charged in such a way, the connecting blocks with transmitter caps form an - obvious fact of risk before blasting is carried out, as powerful mechanical impact, such as being violently run over by heavy vehicles or hit by falling objects may affect the transmitter capl so that an unintentional initiation of the detonator unit occurs. The connecting block certainly implies very satis-factory protection, but very unfavourable circumstances may unfortunately cause an undesired initiation with devastating effect.
The purpose of the present invention is to create a system of fuses for blasting, so that the risk of unintentional initiation is considerably reduced. According to the invention ~ this is accomplished by using 3 fuse elements containing low~
-~ energy fuses. One of the fuse elements (borehole unit) is provided with a detonator in one end, and in the other end the ~ , fuse is free. This fuse element is placed in a borehole, which - is then filled with explosives~ All the boreholes are put in order and are provided with fuses in accordance with the above-mentioned and explosives. In order to effect connection a number of fuse elements are then used, which have one end free and the other end fitted with a connecting block containin~ a

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transmitter cap with or without a delay element. Alternatively or in addition~ for connecting up fuse elements with a connect-ing block in each end are used, the connecting block containing a transmitter cap with or without delay.
All of the connecting blocks can take one or more free fuse erds or double-folded fuses, which can receive the shock wave from the initiating transmitter cap~ Thus, the ends of the fuses protruding from the boreholes can be connected with fuse ele~ents containing connecting blocks, and these fuse elements on their part with each other, so that a connection pattern is obtained, according to which the fuses in the boreholes are in-itiated, and then certain transmitter caps can be delay caps.
The established network of fuses has then a fuse with a connect-ing block, which fuse has a free end connected to an initiator, which in this case can for instance be an acorn pistol. Thus, the advantage of the present invention is that all of the holes can be bored and filled with fuses and explosives without any transmitter cap whatsoever existing on the surface of the sur-rounding rock. The transmitter caps will not appear until all of the boring and charging operations have been made. The present invention has been given the designation System NOMEL (R) GT.
In accordance with a specific embodiment, a system for blasting of objects such as rock, concrete and the like, where the objects are provided with a number of boreholes con-taining fuses with detonators and explosives such as dynamite, water-gel explosive and the like, where the fuse is a low-ener~y fuse suitably consisting of a flexible tube which is coated inside with an explosive or another reactive substance, and where the fuse is cooperating with connecting-blocks and transmitter caps, is characterized by the fact, that it is composed of a number of, preferably three, types of fuse ~ 3 ~

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elements, namely a first type (type A), where the fuse in one end is fitted with a delay or instantaneous detonator and in the other end is free, said first type of fuse elements introduced into boreholes with their free ends protruding outside the surface of the ground or the rock, and two further types (type B and type C) provided in one end (type B) or in both ends (type C) with connecting blocks made of e.g. plastic material, which contain transmitter caps which can be instan-taneous transmitter caps or delay transmitter caps, and which - 10 blocks can receive one or more fuses to transmit initiation to these fuses, that the free ends of the fuses in the boreholes are connected with connecting blocks, to which blocks the free end of fuse elements (type B) and/or double-folded fuse (type C) are connected, and that one end of a fuse element (type B) is connected to an initiator, which ~rings about initiation of ~ the system.
- The present invention will be described in more detail ~ ;
with reference to the accompanying drawings, in which:
Fig. 1 shows a fuse element, where one end of the fuse is free, whereas the other end is fitted with a detonator with or without a delay element for the initiation of the surrounding explosive, Fig. 2 shows a fuse element, which is free in one - end and which is fitted in the other end with a connecting ~ block containing a transmitter cap with or without a delay ; element, Fig. 3 shows a fuse element, which in both ends is fitted with a connecting block containing a transmitter cap which can ~e an instantaneous or delay transmitter cap, Fig. 4 shows the way a fuse elqment, which is fitted in one end with a detonator according to Fig. 1, in lOB~3~0 ..
its other end is connected with a connecting block with a transmitter cap, Fig. 5 shows in more detail an example of a connect-ing block containing a transmitter cap and a cavity for receiving a fuse ?
Fig. 6 shows in a simplified way the system in the `- charging phase with a number of boreholes, into each of which a fuse element according to Fig. 1 is introduced, Fig. 7 shows in a simple case the way one of the various fuse elements can be used in the connecting phase, Fig. 8 shows a connected round, for instance for blasting of trenches, where each fuse element can initiate i 3 borehole units and another fuse element according to Fig. 2.
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Figs. 9-10 show further examples o~ connecting æ' system3, for instance for bench blasting, Fig~ 11 shows doublimg of the capacity by using fuse elements according to Fig. 3, Figs. 12-14 show various connecting alternatives, where fuse elements containing a transmitter cap with delay - are combined, so that desired blasting geometry is obtained~
- In more detail, Figs. 1-3 illustrate in principle the fuse elements of which the system in question is built up.
The elements are in sequence marked A, B and C. The element A in Fig. 1 has one end of the fuse 1 connected with the ~-detonator 2, The element B in Fig. 2 has one end of the fuse 1' connected with a connecting block 4 containing a transmitter cap 3. In Fig. 3, which shows the element C, one end of the fuse 1~ is connected with a connecting block

4' containing a transmitter cap 3' and the other end to d connecting block 4" with a tran mitter cap 3n, Fig. 4 illus-trates the way a fuse element A consisting of the fuse 1"' and the detonator 2' has its free end connected with a connecting block 4"'containing a transmitter cap 3"', . . ~ :~ ..
- In Fig. 5 a) stands for a connecting ~lock, ;
- b) for a partial cross-section of a transmitter cap and c) for an introduced fuse for initiation.
- In Fig. 6 5, 5', 5`' etc denote boreholes, in o - which fuse elements A according to Fig. 1 are introduced with their free ends protruding outside the surface of the rock.
In Fig. 7 the fuse elements A are connected up . . :
by employing fuse elements B according to FigO 2, fitted ;

with diayrammatically indicatea connecting blocks 6, 6', 6~' etc.
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In Figs. 8-11 each borehole is marked H and the ~ connecting blocks K. The use of the various fuse elements, A, B and C is evident from the connecting diagrams.
Initiation is effected with an initiator arranged at the free end D of a fuse element B.
In a connecting example according to Fig. 10 the requisite material consists of borehole units in adjusted lengths (fuse ~- element A); short fuse elements B with instantaneous transmitter cap (connecting block Kl).
,~ Fig. 11, which illustrates an established connection with partly double connecting units suitable for underground work and otherapplications with a tight bore geometry, does not require any detailed description. The transmitter cap in the connecting blocks is an instantaneous transmitter cap (connecting block Kl).
Fig. 12 represents a conceivable combination with interval transmitter caps. The requisite material consists of borehole units in adjusted lengths, only -~ one interval, in this example No. 10 = 250 ms (fuse element A), short fuse elements B with interval trans-~ mitter cap, in this example interval - 1 = 25 ms (connecting block K2) between al] holes and between the rows of holes.
Notice: The initiation on the surface will be 10 holes crosswise or 10 rows b2fore the firing sequence. Fine security against tearing off is obtained. me blasting geometry is pronouncedly wedge-shaped. The numbering of '-.,` ~ .

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the boreholes ~10-17) indicates the intervals and constitutes th~ sum of the constant interval (No. 10) in the borehole and a number of delay transmutter caps, which all have an interval 1 (connecting block K2).
Fig. 13 illustrates another possible combination with interval transmitter caps. The requisite material consists in this case of - borehole units in adjusted lengths, only on~ interval, in this example No. 10 = 250 ms (fuse element A);
, short fuse elements B with instan-`~ taneous transmitter cap (connecting : block Kl) between holes in the same row which are to have the sam~
interval: -short fuse elements B with interval transmitter cap, in this example interval 1 = 25 ms (connecting block K2) for connection when delay is wanted, i.e. for edge holes and between the rows.
Notice: In this example th~ initiation on the surface will be 10 rows before the firing sequence, which means fine -` security against tearing off.
Fig. 14 illustrates yet another conceivable com-bination with interval transmitter caps. The material consists of borehole units in adjusted lengths, only one interval, in this example No. 80 = 2000 ms ~fuse element A), 3~

short fuse elements with interval transmutter cap, in this example ' interval 6 = 150 ms with connecting I block K7.
The numhering at the sido of the holes indicates , the initiatlon sequence.
Notice: In this example the initiation on th~ ~urface is completed after 1200 ms, and thus the safety against ' tearing off is perfect.
In addition to its simplicity in practisin~, the present invention offers considerable improvement of safety and economic advantage as far as the field use i9 con~
cerned, as will appear below:
1. The charging operation is often performed at the same time as rock boring is going on and heavy machines are present, and a considerable number of people are required.
No connecting units will have to lie on the surface of the rock at that time: they will come later when the boring and the charging have in principle been finished, The connecting work is then usually performed by one or two men and mostly without the assistance of any machines.
2. In a connected-up round the number of connecting points can be cut down by 2~3 reducing the cost of the initiation system and offering an easier visual checking of th~ system.
3. mrough simplified connecting the risk of faulty connecting i5 reduced and thus even the risk of misfires.

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` 4. Possibility of connecting up systems with in- ~
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creased reliability in operation ~double coupiing or -- 30 two-way initiation).
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5. Liberty to decide afterwards upon the interval3 at boreholes bored and charged beforehand.

6, Considerable reduction of assortment (with a 10-factor) is possible.

7. Simplified and safer m~nufacture, smaller quan~
tities of explosives tc> be handled in the factory.

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Claims

The embodiments of the invention in which an exclu-sive property or privilege is claimed are defined as follows:-

1. A system for blasting of objects such as rock, concrete and the like, where the objects are provided with a number of boreholes containing fuses with detonators and explosives such as dynamite, water-gel explosive and the like, where the fuse is a low-energy fuse suitably consist-ing of a flexible tube which is coated inside with an explosive or another reactive substance, and where the fuse is cooperating with connecting blocks and transmitter caps, characterized by the fact, that it is composed of a number of, preferably three, types of fuse elements, namely a first type (type A), where the fuse in one end is fitted with a delay or instantaneous detonator and in the other end is free, said first type of fuse elements introduced into boreholes with their free ends protruding outside the surface of the ground or the rock, and two further types (type B and type C) provided in one end (type B) or in both ends (type C) with connecting blocks made of e.g. plastic material, which contain transmitter caps which can be instantaneous transmitter caps or delay transmitter caps, and which blocks can receive one or more fuses to transmit initiation to these fuses, that the free ends of the fuses in the bore-holes are connected with connecting blocks, to which blocks the free end of fuse elements (type B) and/or double-folded fuse (type C) are connected, and that one end of a fuse element (type B) is connected to an initiator, which brings about initiation of the system.