High voltage electric pulse rock drilling

Abstract

A drilling apparatus 100 for high voltage electrical pulse rock drilling, the drilling apparatus 100 comprising: a pulsed power generator 110 for generating a high voltage electrical pulse; a drill (120) for forming a borehole (195) by delivering the generated high voltage electrical pulse through the mineral matrix (190) via an electrode (180) in the drill (120); at least one switch 300 arranged between the pulsed power generator 110 and the electrode 180, the switch 300, when closed, allowing a high voltage electrical pulse from the pulsed power generator 110 to reach the electrode 180; and a switch control device 160. The switch 300 is preferably a controllable switch comprising a switch closing device 350 which is controlled to close the switch 300 by receiving a switch trigger signal emitted from a switch control means 160. The switch control device 160 is preferably arranged to synchronize the switch trigger signal with the high voltage electrical pulse from the pulsed power generator 110.

Description

TECHNICAL FIELD

[0001] The present disclosure generally relates to apparatuses and methods for high-voltage electric pulse rock drilling, which is achieved by passing a pulsed electric current through a mineral matrix. The disclosed apparatuses and methods can be applied, for example, in rock drilling, concrete processing, mineral processing, and continuous mining. BACKGROUND

[0002] In the field of rock drilling, new technologies have emerged in recent years, such as electric pulse boring (EPB), plasma channel drilling, pulse plasma drilling, etc. The technology relies on mechanical electrodes coming into contact with rock material and the application of high voltage between the electrodes. The resulting discharge, if successful, penetrates the rock material and loosens small pieces.

[0003] When a pulse generator connected to electrodes in a conductive medium, such as water, is charged, parasitic discharges through the medium between the electrodes must be limited.

[0004] Therefore, there is a need for improved apparatuses and methods for high-voltage electric pulse rock drilling. SUMMARY

[0005] The above problems are solved by the claimed drilling apparatus and method for high-voltage electric pulse rock drilling.

[0006] The drilling apparatus preferably comprises: a pulse power generator for generating high-voltage electric pulses; a drill tool for forming a borehole by delivering the generated high-voltage electric pulses through a mineral matrix, such as a rock material, via electrodes in the drill tool; a switch arranged between the pulse power generator and the electrodes, wherein the switch, when closed, allows the high-voltage electric pulses from the pulse power generator to reach the electrodes; and a switch control device. The switch is preferably a controllable switch comprising a switch closing device that is controlled to close the switch by receiving a switch trigger signal emitted from the switch control device.

[0007] The method for high-voltage electric pulse rock drilling can be performed using a drilling apparatus comprising: a pulse power generator, a drill tool comprising electrodes, and a controllable switch arranged between the pulse power generator and the electrodes, wherein the switch, when closed, allows high-voltage electric pulses from the pulse power generator to reach the electrodes. The method can comprise: generating high-voltage electric pulses using the pulse power generator; forming a borehole by delivering the generated high-voltage electric pulses through a mineral matrix, such as a rock material, via the electrodes; and controlling a switch closing device to close the controllable switch. The switch closing device is preferably controlled by: receiving a switch trigger signal emitted from a switch control device; and closing the controllable switch based on the switch trigger signal.

[0008] The claimed apparatus and method enable limitation of parasitic discharge of the pulse power generator by allowing the pulse power generator not to be connected to the electrodes all the time.

[0009] In an embodiment, the pulse power generator comprises a pulse transformer in the form of a set of capacitors and is arranged to generate a high voltage electrical pulse each time the switch is closed. This is an effective way of limiting parasitic discharge of the pulse power generator by allowing the pulse power generator not to be connected to the electrodes during charging of the set of capacitors.

[0010] In an embodiment, the pulse power generator is arranged to generate a high voltage electrical pulse continuously and the switch control device is arranged to synchronize the switch trigger signal with the high voltage electrical pulse from the pulse power generator. This ensures that the high voltage electrical pulse generated by the pulse power generator is delivered to the electrodes with an optimal pulse shape.

[0011] In an embodiment, the switch control device is controlled to emit the switch trigger signal for each high voltage electrical pulse generated by the pulse power generator.

[0012] In an embodiment, the switch control device is controlled to emit the switch trigger signal with a fixed timing in relation to the high voltage electrical pulse generated by the pulse power generator.

[0013] In an embodiment, the switch control device is arranged to synchronize the switch trigger signal with the high voltage electrical pulse from the pulse power generator by also using the switch trigger signal for triggering the pulse from the pulse power generator. This is a simple way of synchronizing the switch trigger signal with the high voltage electrical pulse from the pulse power generator, which can for example be implemented using a common control unit.

[0014] In an embodiment, the switch comprises a spark gap between the switch electrodes filled with a switch gas and the switch closing device causes ionization of the switch gas and thereby closure of the switch. This is a reliable way of arranging the switch compared to mechanical solutions which can be unreliable at high voltages.

[0015] In an embodiment, the switch closing device comprises a light emitting device which causes ionization of the switch gas by emitting light into the switch gas. This is a simple switch closing device which still allows for precise control of the closure of the switch, since the light emitting device can be electrically isolated from the switch electrodes.

[0016] In an embodiment, the switch closing device comprises a radiation source which causes ionization of the switch gas by emitting radioactive radiation into the switch gas. This embodiment of the switch closing device allows for precise control of the closure of the switch, since the radiation source can be electrically isolated from the switch electrodes.

[0017] In an embodiment, the switch closing device comprises a pilot electrode arranged such that there is a pilot spark gap between the pilot electrode and one of the switch electrodes, wherein the pilot spark gap is much smaller than the spark gap between the switch electrodes, and ionization of the switch gas is caused by a voltage applied to the pilot electrode causing the pilot spark gap to break down. This causes the electrons and ions generated in the pilot spark gap to migrate into the main spark gap, where the electrons and ions will be accelerated due to the large electric field in the main spark gap, causing avalanche ionization of the switch gas in the pressurized cavity, and thereby causing the main spark gap between the first and second switch electrodes to break down. This allows very precise control of the closing of the switch, since the voltage required for the pilot is low enough that it can be handled by common solid state components such as thyristors.

[0018] In an embodiment, the drilling apparatus comprises more than one switch, such as in the example of two switches. This enables both electrodes to be disconnected from the pulse power generator.

[0019] The above problems are further solved by using the above drilling apparatus for the claimed use of breaking up a mineral matrix such as in any one of rock drilling, concrete processing, mineral processing, and continuous mining.

[0020] The above problems are also solved by the claimed rock drill comprising the above drilling apparatus.

[0021] The scope of the application is defined by the claims, which are incorporated herein by reference in this section. A more complete understanding of embodiments of the application will be obtained by considering the following detailed description in conjunction with the accompanying drawings, in which: BRIEF DESCRIPTION OF DRAWINGS

[0022] Figure 1 schematically illustrates an embodiment of a drilling apparatus for high voltage electric pulse rock drilling according to one or more embodiments described herein.

[0023] Figure 2 schematically illustrates a rock drill according to one or more embodiments described herein.

[0024] Figure 3a and Figure 3b schematically illustrates an embodiment of a controllable switch in a drilling apparatus for high voltage electric pulse rock drilling according to one or more embodiments described herein.

[0025] Figure 4 schematically illustrates a method for high voltage electric pulse rock drilling according to one or more embodiments described herein.

[0026] The embodiments of the present disclosure, together with their advantages, can be best understood from the following detailed description taken in conjunction with the accompanying drawings. It is to be noted that the same reference numerals are adopted to denote the same elements across one or more drawings. DETAILED DESCRIPTION

[0027] The present disclosure generally relates to an apparatus and a method for high-voltage electric pulse rock drilling, which is achieved by passing a pulsed electric current through a mineral matrix. Embodiments of the disclosed solution are presented in more detail in connection with the accompanying drawings.

[0028] Figure 1 An embodiment of a drilling apparatus 100 for high-voltage electric pulse rock drilling is schematically illustrated. Figure 1 The drilling apparatus 100 schematically illustrated in comprises a pulsed power generator 110 for generating high-voltage electric pulses, and a drill tool 120 extending in an axial direction of the drilling apparatus 100 between a front end 121 and a rear end 122, the front end 121 being configured to be located near or at a surface of a mineral matrix 190. A pair of electrodes 180 is arranged at the front end 121 of the drill tool 120, protruding slightly therefrom. Each of the electrodes 180 can comprise a solid electrode portion having an electrically conductive outer shell, so that the high-voltage electric pulses generated by the pulsed power generator 110 pass through the outer shell and reach the solid electrode portion, where a discharge is formed between the solid electrode portion and the mineral matrix 190. The high-voltage electric pulses can thus conduct between the solid electrode portion of the first electrode and the solid electrode portion of the second electrode via the mineral matrix 190, forming a plasma channel in the mineral matrix 190, as a result of which the mineral matrix 190 is broken. Figure 1 The drilling apparatus 100 schematically illustrated in further comprises a liquid supply system 140, which can be used to supply a shielding liquid to an area between the drill tool 120 and the mineral matrix 190.

[0029] Figure 2 An embodiment of a drilling apparatus 100 for high-voltage electric pulse rock drilling is schematically illustrated. Figure 1 A rock drill rig 200 of the drilling apparatus 100 schematically illustrated in drills a hole 195 in a mineral matrix 190 in the form of rock. As Figure 2The drilling apparatus 100 can be several meters long, as illustrated in the middle. The rock drill 200 can comprise an alternating current (AC) power source 113 for powering the pulsed power generator 110. It can further comprise a liquid supply system 140, and preferably also a compressed gas supply system 130. A hydraulically, pneumatically or electrically actuated arm 210 is preferably provided for at least vertical positioning of the drilling apparatus 100, such as in response to a signal from one or more position sensors (not shown) or similar sensors sensing the distance between the electrode 180 and the surface of the mineral matrix. The rock drill 200 preferably further comprises a ground engaging member 220 for moving the rock drill 200 in a direction parallel to the surface of the rock 190.

[0030] The pulsed power generator 110 is configured to generate pulses, such as nanosecond (ns) pulses, to the electrode 180 for breaking up the mineral matrix 190. The electrode 180 is connectable to the pulsed power generator 110 through one or more controllable switches 300, which allow high voltage electrical pulses from the pulsed power generator 110 to reach the electrode 180 when the controllable switches 300 are closed. Each controllable switch 300 typically comprises a semiconductor switch, such as an IGBT, a MOSFET or a thyristor, and a control terminal for controlling the switch 300. Figures 3a to 3b The switch closing device 350, as illustrated in the middle, controls the closing of the switches 300 by receiving a switch trigger signal emitted from the switch control device 160. The switch control device 160 can be arranged to synchronize the switch trigger signal with the high voltage electrical pulses from the pulsed power generator 110, or to control the timing of the closing of the switches 300 based on other parameters, e.g. parameters related to the properties of the mineral matrix or the drilling operation.

[0031] The controllable switches 300 can thus be controlled using the switch trigger signal to synchronize them with, for example, the high voltage electrical pulses from the pulsed power generator 110. When the controllable switches 300 are closed, the high voltage electrical pulses pass between the electrodes 180, and the mineral matrix 190 is thereby broken up.

[0032] Figure 1The schematically illustrated pulse power generator 110 comprises a pulse transformer 112 in the form of a set of capacitors, which is connected to an alternating current (AC) power source 113 via a transformer 111. Using controllable switches 300, short high voltage pulses can be generated, which are then transmitted to the electrodes 180. However, the use of a set of capacitors is particularly sensitive to parasitic discharges through the electrodes 180 during charging of the capacitors, and therefore some method to limit the parasitic discharges is desirable. The proposed controllable switches 300 are an effective way to achieve limitation of parasitic discharges of the pulse power generator 110 by allowing the pulse power generator 110 to be disconnected from the electrodes 180 during charging of the set of capacitors. Since the purpose of the one or more controllable switches 300 is to limit parasitic discharges through the electrodes 180 during charging of the capacitors in the pulse transformer 112, it is important that the one or more controllable switches are not closed during charging. In this embodiment, it is the closing of the one or more controllable switches 300 that generates the high voltage electrical pulses, and therefore no further synchronization is required. However, in this embodiment, it can be desirable to control the timing of the closing of the one or more controllable switches 300 based on parameters such as the state of charge of the set of capacitors or parameters related to the properties of the e.g. mineral matrix or the drilling operation.

[0033] Of course, other embodiments of the pulse power generator 110 can also be used instead. If the pulse power generator 110 generates pulses independently of the controllable switches 300, the switch control device 160 can be controlled to emit a switch trigger signal for every high voltage electrical pulse generated by the pulse power generator 110, but the switch control device 160 can also be controlled to emit a switch trigger signal only for every second or third or fourth high voltage electrical pulse generated by the pulse power generator 110. Thus, the switches 300 do not have to be closed for every high voltage electrical pulse generated by the pulse power generator 110 - this only affects the frequency of the high voltage electrical pulses reaching the electrodes 180. The synchronization of the switch trigger signal with the high voltage electrical pulses from the pulse power generator 110 ensures that the high voltage electrical pulses generated by the pulse power generator 110 are delivered to the electrodes 180 with optimal pulse shape. The switch control device 160 is preferably controlled to emit the switch trigger signal with a predetermined timing in relation to the high voltage electrical pulses generated by the pulse power generator 110.

[0034] The one or more controllable switches 300 can be any type of switch 300 comprising a switch closing device 350, which can be controlled by the switch trigger signal from the switch control device 160. Figures 3a to 3bTwo different embodiments of such controllable switch 300 are schematically illustrated. In both embodiments schematically illustrated, the switch 300 comprises a pressurized cavity 310 filled with a switch gas, in which a first switch electrode 330 and a second switch electrode 330 are arranged. The switch gas between the first switch electrode 330 and the second switch electrode 330 creates a spark gap 320. In both embodiments schematically illustrated, there is also a switch closing device 350, which causes ionization of the switch gas in the pressurized cavity 310, and thereby causes closing of the switch 300. Both switches 300 schematically illustrated thus comprise a spark gap 320 between switch electrodes 330 filled with a switch gas, wherein a switch closing device 350 causes ionization of the switch gas, and thereby causes closing of the switch 300. This is a reliable way of arranging the switch 300, in contrast to mechanical solutions, which can be unreliable at high voltages. A suitable gas that can be used as switch gas is for example nitrogen or ordinary air. If very short high voltage electrical pulses are desired, SF6 can be used as switch gas.

[0035] Figure 3a A UV triggered switch 300 is schematically illustrated. In this embodiment, the switch closing device 350 can for example comprise a light emitting device 360, such as a laser or a UV led, and a light guide 365, which guides the UV light emitted from the light emitting device 360 to the pressurized cavity 310. When the UV light reaches the switch gas in the pressurized cavity 310, the switch gas is ionized, which causes the spark gap between the first switch electrode 330 and the second switch electrode 330 to close, and thereby causes the switch 300 to close. In this embodiment, the switch trigger signal from the switch control device 160 causes the light emitting device 360 to produce light. This is a simple switch closing device 350 that still allows for precise control of the closing of the switch 300, since the light emitting device 360 can be electrically isolated from the switch electrodes 330.

[0036] Figure 3bA high voltage (HV) trigger switch 300 is schematically illustrated. In this embodiment, the switch closing device 350 can for example comprise a firing electrode 370 arranged at a distance from one of the switch electrodes 330 that is much smaller than the distance between the switch electrodes 330. This creates a small spark gap 375 between the firing electrode 370 and the nearest one of the switch electrodes 330, here referred to as the "firing spark gap". Because the distance between the firing electrode 370 and the nearest one of the switch electrodes 330 is much smaller (orders of magnitude less than 1 mm) than the distance between the switch electrodes 330, the voltage required to ionize the firing spark gap is small (200 V to 5000 V) compared to the breakdown voltage of the spark gap (> 50 kV). This allows very precise control of the switch, because the voltage required for the firing is low enough that it can be handled by common solid state components such as thyristors. Thyristors in turn can be triggered using the logic circuitry of a microcomputer. The voltage can for example be supplied to the circuit using an isolation transformer or wireless power transfer technology. The circuit can for example contain a light controlled thyristor that relays the small voltage to the firing electrode 370. This causes the firing spark gap 375 between the firing electrode 370 and the nearest one of the switch electrodes 330 to break down, as illustrated in Figure 3b , and causes the electrons and ions produced there to migrate into the main spark gap. These migrating charges will be accelerated due to the large electric field in the main spark gap, causing an avalanche ionization of the switch gas in the pressurized cavity 310, and thereby causing the main spark gap between the first switch electrode 330 and the second switch electrode 330 to break down, and thus causing the switch 300 to close.

[0037] Other embodiments of the controllable switch 300 can be used, including other embodiments of the controllable switch 300 comprising a spark gap 320 filled with a switch gas between the switch electrodes 330, wherein the switch closing device 350 causes ionization of the switch gas, and thereby causes the switch 300 to close. Such a controllable switch 300 can for example be a radioactive radiation trigger switch 300. In this embodiment, the switch closing device 350 can for example comprise a radiation source and a radiation guide that guides the radioactive radiation emitted by the radiation source to the pressurized cavity 310. When the radioactive radiation reaches the switch gas in the pressurized cavity 310, the switch gas is ionized, which causes the spark gap between the first switch electrode 330 and the second switch electrode 330 to close, and thereby causes the switch 300 to close. In this present embodiment, the switch trigger signal from the switch control device 160 causes the radiation source to produce the radioactive radiation. This embodiment of the switch closing device 350 allows precise control of the closing of the switch 300, because the radiation source can be electrically isolated from the switch electrodes 330. This embodiment can be set up very similarly to the UV trigger switch 300 of Figure 3a .

[0038] In embodiments where the pulsed power generator 110 generates pulses independently of the controllable switch 300, the switch control device 160 can be arranged to synchronize the switch trigger signal with the high voltage electrical pulses from the pulsed power generator 110 by also using the switch trigger signal for triggering the pulses from the pulsed power generator 110. The switch control device 160 can emit the switch trigger signal in response to a signal received from an external control unit 170, such as a control unit of a rock drill machine 200 in which the drilling apparatus 100 is provided. In this case, the signal from the external control unit 170 can also be used for triggering the pulses from the pulsed power generator 110.

[0039] The switch control device 160 can comprise a microprocessor, a microcontroller, a programmable digital signal processor or another programmable device. Thus, the switch control device 160 can comprise electronic circuitry and connections (not shown) as well as processing circuitry (not shown) for communication with different components of the drilling apparatus 100 as well as the external control unit 170. For example, the switch control device 160 can be configured to communicate with various sensors, devices, systems and control units of the drilling apparatus 100. In the illustrated embodiment, the switch control device 160 controls the transformer 111 as well as the switch 300. Although not shown, the switch control device 160 can also be used for controlling the liquid supply system 140 and / or the compressed gas supply system 130. Alternatively, several separate control units can be provided.

[0040] The switch control device 160 can comprise hardware or software modules, or partly hardware or software modules, and communicate using known transmission buses such as CAN bus and / or wireless communication functionality. The processing circuitry can be a general purpose processor or a special purpose processor. The switch control device 160 can comprise non-transitory memory for storing computer program code and data. Thus, the skilled person realizes that the switch control device 160 can be implemented in many different configurations.

[0041] The drill 120 can be any type of drill suitable for forming a borehole by delivering high voltage electrical pulses through a mineral matrix 190. The drill 120 can use any combination of electrodes 180. The drilling apparatus 100 can comprise a plurality of electrode pairs arranged around the periphery of the front end 121 of the drill 120. At the center of the drill 120, there can be an outlet of a shield liquid conduit extending from the liquid supply system 140, but there can be various different configurations.

[0042] Figure 4A method 400 for high-voltage electric pulse rock drilling using a drilling apparatus 100 comprising a pulse power generator 110, a drill 120 comprising an electrode 180, and a controllable switch 300 arranged between the pulse power generator 110 and the electrode 180, wherein the switch 300 when closed allows high-voltage electric pulses from the pulse power generator 110 to reach the electrode 180, is schematically illustrated. The method 400 can comprise:

[0043] A step 410 of generating a high-voltage electric pulse using the pulse power generator 110.

[0044] A step 420 of forming a borehole 195 by delivering the generated high-voltage electric pulse through the mineral matrix 190, such as a rock material, via the electrode 180.

[0045] A step 450 of controlling the switch closing device 350 to close the controllable switch 300.

[0046] A step 460 of receiving a switch trigger signal emitted from the switch control device 160 in the switch closing device 350.

[0047] A step 470 of closing the controllable switch 300 based on the switch trigger signal.

[0048] This enables limitation of the pulse power generator 110 parasitic discharge to the electrode 180 by allowing the pulse power generator 1110 not to be connected to the electrode 180 all the time.

[0049] The above steps can be implemented in any order that has a technical meaning, and some of the steps can be implemented simultaneously with each other.

[0050] In an embodiment, the pulse power generator 110 comprises a pulse transformer 112 in the form of a set of capacitors, and the generating 410 of a high-voltage electric pulse comprises generating a high-voltage electric pulse each time the switch 300 is closed. This is an effective way of limiting the pulse power generator 110 parasitic discharge by allowing the pulse power generator 110 not to be connected to the electrode 180 during charging of the set of capacitors.

[0051] In an embodiment, the generating 410 of a high-voltage electric pulse comprises continuously generating a high-voltage electric pulse, and the controlling 450 of the switch closing device 350 comprises synchronizing the switch trigger signal with the generated high-voltage electric pulse. This ensures that the high-voltage electric pulse generated by the pulse power generator 110 is delivered to the electrode 180 with an optimal pulse shape.

[0052] In an embodiment, the drilling apparatus 100 comprises more than one switch 300. This enables both electrodes 180 to be disconnected from the pulse power generator 110.

[0053] The method 400 can further comprise one or more of the following:

[0054] Step 430: The switch control device 160 is controlled to emit a switch trigger signal for each high voltage electrical pulse generated by the pulse power generator 110. This enables each high voltage electrical pulse generated by the pulse power generator 110 to be delivered to the electrode 180.

[0055] Step 440: The switch control device 160 is controlled to emit a switch trigger signal with a fixed timing in relation to the high voltage electrical pulses generated by the pulse power generator 110. This ensures that the high voltage electrical pulses generated by the pulse power generator 110 are delivered to the electrode 180 while still enabling a limitation of the pulse power generator parasitic discharges.

[0056] Step 480: The switch trigger signal is also used to trigger the pulses from the pulse power generator 110 in order to synchronize the switch trigger signal with the high voltage electrical pulses from the pulse power generator 110. This is a simple way of synchronizing the switch trigger signal with the high voltage electrical pulses from the pulse power generator, which can be implemented, for example, using a common control unit 170 in embodiments where the pulse power generator 110 generates the pulses independently of the controllable switch 300.

[0057] Step 490: For a switch 300 comprising a spark gap 320 filled with a switch gas between the switch electrodes 330, using the switch closing device 350 causes ionization of the switch gas and thereby causes closing of the switch 300. This is a reliable way of arranging the switch 300 compared to mechanical solutions which can be unreliable at high voltages.

[0058] If the switch closing device 350 comprises a light emitting device 360, the causing 490 of ionization of the switch gas can involve using the light emitting device 360 to emit light into the switch gas. This is a simple switch closing device 350 which still allows for precise control of the closing of the switch 300, as the light emitting device 360 can be electrically isolated from the switch electrodes 330.

[0059] If the switch closing device 350 comprises a radiation source, the causing 490 of ionization of the switch gas can involve using the radiation source to emit radioactive radiation into the switch gas. This embodiment of the switch closing device 350 allows for precise control of the closing of the switch 300, as the radiation source can be electrically isolated from the switch electrodes 330.

[0060] If the switch closing device 350 comprises a pilot electrode 370 arranged such that there is a pilot spark gap 375 between the pilot electrode 370 and one of the switch electrodes 330, where the pilot spark gap 375 is much smaller than the main spark gap 320 between the switch electrodes 330, the causing 490 of ionization of the switch gas can involve applying a voltage to the pilot electrode 370, causing the pilot spark gap 375 to break down. This causes the electrons and ions generated in the pilot spark gap 375 to migrate into the main spark gap 320, where the electrons and ions will be accelerated due to the large electric field in the main spark gap 320, causing an avalanche ionization of the switch gas in the pressurized cavity 310, and thereby causing the main spark gap 330 between the first and second switch electrodes 330 to break down. This allows for very precise control of the closing of the switch 300, since the voltage required for the pilot is low enough that it can be handled by common solid state components such as thyristors.

[0061] The above steps can be implemented in any order that has technical significance, and some of the steps can be implemented simultaneously with each other.

[0062] The foregoing disclosure is not intended to limit the application to the precise forms or specific uses disclosed. It is contemplated that various alternatives to the embodiments of the disclosure described herein, or portions thereof, can be made in light of the disclosure. Accordingly, the scope of the application is defined only by the claims.

Claims

1. A drilling apparatus (100) for high-voltage electric pulse rock drilling, the drilling apparatus (100) comprising: a pulse power generator (110) for generating high-voltage electric pulses; a drill tool (120) for forming a borehole (195) by delivering the generated high-voltage electric pulses through a mineral matrix (190) via an electrode (180) in the drill tool (120); a switch (300) arranged between the pulse power generator (110) and the electrode (180), wherein the switch (300) allows high-voltage electric pulses from the pulse power generator (110) to reach the electrode (180) when closed; and a switch control device (160), wherein the switch (300) is a controllable switch comprising a switch closing device (350) arranged to be controlled to close the switch (300) by receiving a switch trigger signal emitted from the switch control device (160).

2. The drilling apparatus (100) according to claim 1, wherein, The pulse power generator (110) comprises a pulse transformer (112) in the form of a set of capacitors and is arranged to generate a high-voltage electric pulse each time the switch (300) is closed.

3. The drilling apparatus (100) of claim 1, wherein, The pulse power generator (110) is arranged to continuously generate high-voltage electric pulses, and the switch control device (160) is arranged to synchronize the switch trigger signal with the high-voltage electric pulses from the pulse power generator (110).

4. The drilling apparatus (100) according to claim 3, wherein, The switch control device (160) is arranged to synchronize the switch trigger signal with the high-voltage electric pulses from the pulse power generator (110) by also using the switch trigger signal for triggering the pulses from the pulse power generator (110).

5. The drilling apparatus (100) according to any one of claims 1 to 4, wherein, The switch (300) comprises a spark gap (320) filled with a switch gas between switch electrodes (330), and the switch closing device (350) causes ionization of the switch gas, and thereby the closing of the switch (300).

6. The drilling apparatus (100) of claim 5, wherein, The switch closing device (350) comprises a light emitting device (360) that causes the ionization of the switch gas by emitting light into the switch gas.

7. The drilling apparatus (100) of claim 5, wherein, The switch closing device (350) comprises a radioactive source that causes the ionization of the switch gas by emitting radioactive radiation into the switch gas.

8. The drilling apparatus (100) of claim 5, wherein, The switch closing device (350) comprises an ignition electrode (370) arranged such that there is an ignition spark gap (375) between the ignition electrode (370) and one of the switch electrodes (330), wherein the ignition spark gap (375) is much smaller than the spark gap (320) between the switch electrodes (330), and the ionization of the switch gas is caused by a voltage applied to the ignition electrode (370) that causes the ignition spark gap (375) to break down.

9. The drilling apparatus (100) according to any one of claims 1 to 8, comprising more than one switch (300).

10. A method (400) for high-voltage electric pulse rock drilling using a drilling apparatus (100), the drilling apparatus (100) comprising: a pulse power generator (110), a drill tool (120) comprising an electrode (180), and a controllable switch (300) arranged between the pulse power generator (110) and the electrode (180), wherein the switch (300) when closed allows high voltage electrical pulses from the pulse power generator (110) to reach the electrode (180), the method (100) comprising: generating (410) high voltage electrical pulses using the pulse power generator (110); forming (420) a borehole (195) by delivering the generated high voltage electrical pulses through the electrode (180) through a mineral matrix (190); and controlling (450) a switch closing device (350) to close the controllable switch (300), wherein the switch closing device (350) is controlled by: receiving (460) a switch trigger signal emitted from a switch control device (160); and closing (470) the controllable switch (300) based on the switch trigger signal.

11. The method (400) of claim 10, wherein, the pulse power generator (110) comprises a pulse transformer (112) in the form of a set of capacitors, and the generating (410) of high voltage electrical pulses comprises generating a high voltage electrical pulse each time the switch (300) is closed.

12. The method (400) according to claim 10, wherein the generating (410) of high voltage electrical pulses comprises generating high voltage electrical pulses continuously, and the controlling (450) of the switch closing device (350) comprises synchronizing the switch trigger signal with the generated high voltage electrical pulses.

13. The method (400) of claim 12, further comprising: the switch trigger signal is also used (480) to trigger the pulses from the pulse power generator (110) so as to synchronize the switch trigger signal with the high voltage electrical pulses from the pulse power generator (110).

14. The method (400) of any of claims 10 to 13, wherein, the switch (300) comprises a spark gap (320) filled with a switch gas between switch electrodes (330), the method further comprising: causing (490) ionization of the switch gas using the switch closing device (350), and thereby causing the closing of the switch (300).

15. The method (400) of claim 14, wherein, the switch closing device (350) comprises a light emitting device (360), and the causing (490) of ionization of the switch gas involves emitting light into the switch gas using the light emitting device (360).

16. The method (400) of claim 14, wherein the switch closing device (350) comprises a radiation source, and the causing (490) of ionization of the switch gas involves emitting radioactive radiation into the switch gas using the radiation source.

17. The method (400) of claim 14, wherein, The switch closing device (350) comprises a firing electrode (370) arranged such that a firing spark gap (375) exists between the firing electrode (370) and one of the switch electrodes (330), wherein the firing spark gap (375) is much smaller than the spark gap (320) between the switch electrodes (330) and the causing (490) of the ionization of the switch gas involves applying a voltage to the firing electrode (370) which causes the firing spark gap (375) to close.

18. The method (400) of any of claims 10 to 17, wherein, The drilling device (100) comprises more than one switch (300).

19. Use of a drilling device (100) according to any one of claims 1 to 9 for breaking a mineral matrix (190), such as in any one of rock drilling, concrete processing, mineral processing and continuous mining.

20. A rock drilling rig (200) comprising a drilling device (100) according to any one of claims 1 to 9.

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