Note: Descriptions are shown in the official language in which they were submitted.
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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
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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
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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"',
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- 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
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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),
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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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