Wired interface

Abstract

A blasting system (10) at a blast site (12) wherein each detonator assembly (20), in a borehole (16), is responsive to a through-the-earth fire signal from a blast controller (34), and can engage in bidirectional communication via at least one interface device (26) with an interrogating device (44), such as a tagger, at the blast site.

Description

WIRED INTERFACEBACKGROUND OF THE INVENTION

[0001] This invention relates generally to a detonator assembly of the type which is responsive to a through-the-earth (TTE) signal sent for example from a blast controller.

[0002] A detonator assembly of the aforementioned kind is preferentially used in certain applications, for example at a blast site where detonator assemblies deployed in respect of boreholes are not connected to one another by means of a wired harness on the surface. Under these conditions the detonator assemblies are designed to be responsive to a TTE signal which is transmitted from a blast controller at a remote and relatively safe site. This type of communication is normally unidirectional i.e. from the blast controller to the detonator assemblies for, in order to transmit a signal in the reverse direction i.e. from a detonator assembly to the blast controller, the detonator assembly must have a relatively strong transmitter which is connected to a suitably designed antenna - requirements which can not economically or technically be met for each detonator assembly.

[0003] The unidirectional characteristic of a blast site established in the aforementioned manner means that although a detonator assembly might receive a signal from the blast controller it is not able to report this to the blast controller. Allied to this is that a detonator assembly is not capable of transmitting a signal on its status, or in response to a test routine, to the blast controller or to some other remotely positioned device. A practical effect of this shortcoming is that a detonator assembly which can be tested to be fully functional beforedeployment is incapable of transmitting information on an operative failure which arises after deployment. The possibility that the detonator assembly might misfire cannot therefore be communicated to a remotely positioned controller.

[0004] An object of the present invention is to address, at least to some extent, this aspect.SUMMARY OF THE INVENTION

[0005] The invention provides a blasting system which comprises a blast site, a plurality of boreholes at the blast site, a blast controller, a plurality of detonator assemblies which are deployed in respective boreholes, each detonator assembly respectively including a communication module, a detonator firing arrangement and a receiver which, responsive to a through-the-earth (TTE) fire signal from the blast controller, causes initiation of the detonator firing arrangement, and a plurality of interface devices at the blast site, each interface device being associated with at least one respective detonator assembly and being configured to engage in bidirectional communication with the communication module of the associated at least one detonator assembly.

[0006] The interface device may be configured to communicate, preferably bidirectionally, with an interrogating or controlling apparatus at the blast site which may be mobile, such as a tagger or an equivalent mechanism.

[0007] The interface device may communicate with the communication module in an associated detonator assembly in any appropriate manner. Such communication may be effected in a wireless way and in that event it is preferable for the interface device to bepositioned at or close to a mouth of the borehole in which the detonator assembly is deployed so that the passage of the borehole provides a path of low attenuation for signal transmission between the interface device and the communication module.

[0008] If the borehole is charged with explosive, e.g. an emulsion, then generally a signal transmitted through the emulsion will be attenuated to a lesser degree than when transmitted through rock.

[0009] A wired interface in the form of a physical communication link can however be established between the interface device and the respective communication module of each associated detonator assembly. The link may comprise one or more electrical conductors, fibre optic cables or the like.

[0010] In one preferred embodiment of the invention at least one detonator assembly includes monitoring structure comprising suitable sensors, to detect and provide information on one or more environmental or other parameters pertaining for example to parameters in or adjacent a borehole in which the detonator assembly is located, for example the temperature in the borehole, the presence of water in the borehole, the humidity level in the borehole or the humidity level in an explosive in the borehole, the presence and nature of an explosive in the borehole, the depth of the detonator assembly in the borehole taken from a mouth of the borehole, and the functional status of the detonator assembly.

[0011] It may be possible for the monitoring structure to check if a TTE signal from the blast controller, sent for example for test purposes, has been received by the communication moduleand to make data in respect thereof available to the interface device.

[0012] It is possible for the interface device, for example in response to a data or command signal sent from an interrogating or controlling apparatus, to initiate the implementation of a test routine at the at least one detonator assembly thereby to determine the operative status of the detonator assembly. Programming and time delay data may be transferred from the interrogating or controlling apparatus to the detonator assembly. One or more signals, responsive to the aforegoing and conveying confirmatory information from or status information on the detonator assembly may be sent from the communication module to the interface device. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] The invention is further described by way of example with reference to the accompanying drawings in which :Figure 1 illustrates a blasting system according to the invention,Figure 2 schematically depicts a detonator assembly which is used in the blasting system of Figure 1 , andFigure 3 represents an interface device suitable for use in the blasting system.DESCRIPTION OF PREFERRED EMBODIMENT

[0014] Figure 1 of the accompanying drawings illustrates, schematically, a blasting system 10 according to the invention.

[0015] The blasting system includes a blast site 12 at which a number of boreholes 16 are drilled at predetermined locations.

[0016] The system includes a plurality of detonator assemblies 20 and at least one respective detonator assembly 20 is deployed in each borehole. At or close to a mouth 22 of each borehole a respective interface device 26 is positioned. A wired interface in the form of a physical link 28 comprising one or more conductors, or fibre optic cables, connects the interface device 26 to the detonator assembly 20. Each borehole 16 is charged with explosive material 30 e.g. an emulsion explosive.

[0017] Figure 1 illustrates an interface device 26 associated with a single borehole 16. That type of arrangement is exemplary, and non-limiting, for one interface device 26 may be linked to several detonator assemblies which are in different boreholes, which are relatively close together. The interface device and each detonator assembly can communicate directly and uniquely with one another, without the possibility that a signal to or from one detonator assembly could go to a different detonator assembly or could be treated as coming from a different detonator assembly - this capability is readily achieved by using a unique identifier, for each detonator assembly, which is included in each signal to or from the detonator assembly in question.

[0018] A blast controller 34 is positioned at a remote location. The blast controller includes a transmitter 36 which is connected to a custom-designed antenna 38. The arrangement is one in which the blast controller, via the transmitter and antenna, is configured to transmit a through-the-earth (TTE) signal 40 to the various detonator assemblies.

[0019] To enable the signal 40 to be reliably received by each detonator assembly 20 the transmitter 36 operates at a suitable power level and frequency, typically of the order of 3 kHz. If appropriate specification requirements are met, a TTE signal can be reliably transmitted from the blast controller 34 to each detonator assembly 20. However, because of power and antenna requirements, which are needed for through-the-earth transmission it is not normally technically and financially feasible for a detonator assembly 20 to be used which is capable of transmitting a return TTE signal to the blast controller. Thus, in the blasting system 10, communications are unidirectional, from the blast controller to the detonator assemblies and not bidirectional.

[0020] Deployment of a detonator assembly 20 into a borehole 16 is accompanied by a test to ensure that, at the time of placement, the detonator assembly is fully functional. Nonetheless, due to various factors which can arise after placement of a detonator assembly, it is possible for a failure or shortcoming of a component to manifest itself as a defect which is such that the detonator assembly 20 would not fire even though a fire command TTE signal from the blast controller 34 is received. Information on this type of misfire situation cannot then be communicated to the blast controller because of the restriction of unidirectional communication.

[0021] To address that situation each detonator assembly 20 is placed in a bidirectional communication mode with a respective interface device 26 which is connected by means of a respective link 28 to the detonator assembly so that bidirectional communication between the detonator assembly 20 and the device 26 can take place. As noted, more than one detonator assembly 20 can be linked to a single interface device.

[0022] At the blast site 12 an operator makes use of an interrogating or control apparatus 44, such as a mobile tagger, to communicate with each interface device 26.

[0023] Figure 2 illustrates in block diagram form the construction of a detonator assembly 20. The assembly includes a housing 48 which contains a transmitter / receiver unit 50 used for local communications, a receiver 52 which is responsive to a through-the-earth signal 40 sent from the transmitter 36, a power supply 54, a monitoring structure 56, a primary explosive 58 and a detonating arrangement 60 which includes a processor 62 and a detonator 64. A unique identifier, for the particular detonator assembly, i8s stored in memory which is linked to the processor. The monitoring structure 56, according to requirement, is adapted to monitor a range of environmental and other parameters such as the detonator assembly status (66), the temperature in a borehole in which the detonator assembly is located (68), the presence and the nature of an explosive placed in a borehole (70), the humidity level in the explosive or the presence of water in the explosive or the borehole (72) and the depth (74) of the detonator assembly, once it is positioned in a borehole, taken from a mouth 22 of the borehole.

[0024] Figure 3 illustrates in block diagram form an interface device 26. This device includes a processor 80, a transmitter / receiver unit 82, a power supply 84 and a memory module 86.

[0025] The detonator assemblies 20 are placed into the respective boreholes using conventional techniques. Each detonator assembly is tied or tethered to a respective interface device 26 by means of the physical link 28. Where appropriate multiple detonator assemblies are tied to a single interface device using separate links 28. Explosive material 30 is then charged into each borehole. The interface device is close to a mouth 22 of the or each boreholeto minimise the length of the link 28 and to reduce the amount of wire or fibreoptic cable (as the case may be) on the surface at the blast site.

[0026] Each detonator assembly, prior to placement into a borehole, is tested to ensure that it is in a fully operative mode. Despite this it is possible that a defect can arise in a detonator assembly during or after the installation process. The nature of the defect may be such that even though the detonator assembly might receive a through-the-earth fire command signal 40 from the blast controller it will be unable to respond and a misfire would then occur.

[0027] An operator using a tagger 44 can traverse the blast site 12 and interrogate each interface device 26 via a signal which is sent to the transmitter / receiver unit 82. The processor 80 in the device 26 has the capability to initiate the transmission of commands and data to the associated detonator assembly or detonator assemblies via the respective physical links 28. This capability enables the device 26 to cause a full functional test to be carried out on the or each detonator assembly, using established routines, and for status signals resulting from those tests to be transmitted by the respective local transmitter / receiver unit 50 to the interface device 26. Data and information from the device 26, and an identifier which is unique to the detonator assembly, can then be collected by the tagger 44 and transferred then or later to the blast controller 34.

[0028] The monitoring structure 56 allows for data on a number of parameters which can influence the blasting process to be collected and for such data to be transmitted, in a way similar to what has been described, to the interface device 26 and then to the tagger 44. As indicated the status (66) of the detonator assembly is monitored or determined by means of atest routine. This includes the functionality of the initiating arrangement 60, the strength of the power supply 54, and the capability to receive the through-the-earth signal 40 in a reliable manner. The temperature (68) and the presence of water or a humidity level (72) can also be measured.

[0029] The depth or the position of the detonator assembly in the borehole can be determined in various ways. For example at the time that the detonator assembly is lowered into the borehole use can be made of a measuring device e.g. a flexible tape measure.

[0030] During operation of the blasting system the site 12 is prepared in the way which has been described in that the boreholes 16 are formed and explosive material 30 is charged into each borehole which contains a detonator assembly 20. A test signal is then sent through-the- earth from the blasting controller 34. Detection of the test signal is assessed by each receiver 52 and data thereon is held in the respective processor 62. Subsequently, upon interrogation by the tagger 44, the relevant data is transmitted via the local communication unit 50 to the associated interface device 26. This data is accompanied by the identifier which uniquely identifies the detonator assembly in question. It can thereby be established that all of the detonator assemblies are operative and, if there is a defect, remedial action can be taken.

[0031] Programming data e.g. timing delays can be transmitted from the tagger 44 to the respective detonator assemblies through the intermediary of the associated interface device26.

[0032] The arrangement, illustrated diagrammatically in Figure 2, also allows for informationwhich may affect a blasting operation to be collected through the use of suitable sensors which are incorporated in the monitoring structure 56. That data is available and is transmitted to the tagger 44 in the manner described. The data can be used in real time or subsequently to determine the effect of a parameter on the blasting process.

[0033] A feature of the arrangement described is that the need for a blasting harness is eliminated i.e. there are no conductive or other wires on the surface of the blast site.

Claims

CLAIMS1. A blasting system (10) which comprises a blast site (12), a plurality of boreholes (16) at the blast site, a blast controller (34), a plurality of detonator assemblies (20) which are deployed in respective boreholes, each detonator assembly (20) respectively including a communication module (50), a detonator firing arrangement (62, 64) and a receiver (52) which, responsive to a through-the-earth (TTE) fire signal (40) from the blast controller (34), causes initiation of the detonator firing arrangement, and which is characterized by a plurality of interface devices (26) at the blast site (12), each interface device (26) being associated with at least one respective detonator assembly (20) and being configured to engage in bidirectional communication with the communication module of the associated at least one detonator assembly.

2. A blasting system according to claim 1 wherein the interface device (26) is configured to communicate, wirelessly or via a physical link, with an interrogating or controlling apparatus (44) at the blast site.

3. A blasting system according to claim 1 wherein at least one detonator assembly (20) includes monitoring structure (56) comprising sensors, to detect and provide information on one or more environmental or other parameters at or adjacent the borehole in which the detonator assembly is located.

4. A blasting system according to claim 1 wherein the interface device (26), for each detonator assembly, in response to a data or control signal sent from an interrogating or controlling apparatus (44), initiates the implementation of a test routine at the at least onedetonator assembly thereby to determine the operative status (66) of the detonator assembly.

5. A detonator assembly (20), for use in the blasting system (10) of claim 1 , which includes a housing (48) which contains a transmitter / receiver unit (50) used for local communications, a receiver (52) which is responsive to a through-the-earth signal (40) sent from a transmitter (36), a power supply (54), a monitoring structure (56), a primary explosive (58) and a detonating arrangement (62, 64) which includes a processor (62) and a detonator (64) wherein the monitoring structure (56) is adapted to monitor the status (66) of the detonator assembly, and environmental parameters at or adjacent a borehole in which the detonator assembly is located (68, 70, 72, 74).

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