Pulsed power drilling tool and method for breaking a mineral matrix

Abstract

A pulsed power drilling tool configured for passing a pulsed electric current through a mineral matrix (400) to break up the mineral matrix, the drilling tool comprising: a pulsed power generator for generating high voltage current pulses; a drill head comprising at least a first electrode (200) and a second electrode (200”), the first electrode comprising a first solid electrode portion (201) and the second electrode comprising a second solid electrode portion (201”), the first and second solid electrode portions being electrically connectable to the pulsed power generator, and at least one ionization device configured for generating at least one ionized fluid volume (210) extending from the first solid electrode portion to a surface of the mineral matrix, so as to allow the high voltage current pulses (150) to pass between the first and second solid electrode portions via the at least one ionized fluid volume and the mineral matrix.

Description

Technical Field

[0001] This disclosure relates to a pulsed power drilling tool for breaking mineral matrices and a method for breaking mineral matrices by passing a pulsed current through them. The disclosed tool and method can be applied, for example, to rock drilling, concrete processing, mineral processing, and continuous mining. Background Technology

[0002] In the field of rock drilling, new technologies have emerged in recent years, such as electrical pulse drilling (EPB), plasma channel drilling, and pulsed plasma drilling. This technology relies on mechanical electrodes that come into contact with the rock material and the application of a high voltage between the electrodes. If the discharge is successful, it penetrates the rock material and breaks up loose fragments. In some applications, insulating fluids are proposed to prevent direct discharge between the electrodes. However, for most applications, water must be used for practical reasons, and in some cases even brine. This makes achieving good contact between the electrodes and the rock material crucial, as the discharge path through water would otherwise become more attractive than the desired discharge path through the rock material.

[0003] Drill bits typically consist of multiple electrode pairs. Since rock surfaces are never perfectly flat, one or more electrodes of the drill bit may not be in direct contact with the rock surface. Therefore, some discharges may occur directly between the electrodes without penetrating the rock material. When discharges fail to penetrate the rock material, efficiency loss occurs. Ultimately, this failed rock penetration results in no rock breaking achieved.

[0004] Early designs proposed individual suspended spring-loaded electrodes, each in contact with the rock. However, these electrodes are fragile and prone to wear. Summary of the Invention

[0005] The primary objective of this disclosure is to provide improved drilling tools and methods for pulsed power drilling in at least one respect. In particular, the aim of achieving such drilling tools and methods is to reduce at least some of the disadvantages associated with prior art pulsed power drilling tools, such as non-penetrating discharge between electrodes, low efficiency, and excessive electrode wear.

[0006] According to a first aspect of this disclosure, at least the primary objective is achieved by a pulsed power drilling tool (hereinafter also referred to as a drilling tool). The drilling tool is configured to pass a pulsed current through a mineral matrix to break the mineral matrix. The drilling tool includes:

[0007] - Pulse power generator, used to generate high-voltage current pulses.

[0008] - A drill bit, comprising at least one pair of first electrodes and second electrodes, the first electrode comprising a first solid electrode portion, the second electrode comprising a second solid electrode portion, the first solid electrode portion and the second solid electrode portion being electrically connectable to a pulse power generator, and

[0009] - At least one ionization device is configured to generate at least one ionized fluid volume extending at least from the surface of the first solid electrode portion to the mineral matrix, so as to allow a high-voltage current pulse to pass between the first solid electrode portion and the second solid electrode portion via the at least one ionized fluid volume and the mineral matrix.

[0010] By providing an ionization device for creating an ionized fluid volume between at least one solid electrode portion and the mineral matrix, a region with high electrical conductivity can be achieved between the solid electrode portion and the mineral matrix. The ionized fluid volume will have significantly higher conductivity than the non-ionized fluid surrounding it, meaning that a high-voltage current pulse will travel from the solid electrode portion through the ionized fluid volume to the mineral matrix. By providing a volume with high conductivity between the solid electrode portion and the mineral matrix, an electrical contact can be achieved between the solid electrode portion and the mineral matrix sufficient to guide current into the mineral matrix without "leaking" into the surrounding environment of the ionized fluid volume. The electrical contact provided in this way does not depend on any mechanical contact between the solid electrode portion and the mineral matrix. Therefore, good electrical contact can be achieved even on uneven matrix surfaces. This reduces the risk of electrode wear and non-penetrating discharge between electrodes, while improving drilling process efficiency.

[0011] Another advantage of this disclosure is that the volume of the ionizing fluid can be readily adapted to the dielectric properties of the mineral matrix, for example, by adjusting the degree of ionization and / or by adjusting the flow rate of the ionizing fluid, such as by changing the diameter of the ionizing fluid volume. The degree of ionization multiplied by the flow rate will result in a certain conductivity of the ionizing fluid, which can be used to reduce the power reflectivity of the mineral matrix surface. This thus increases the possibility of impedance matching.

[0012] A high-voltage current pulse will generate a plasma channel in the mineral matrix, through which the current pulse is transmitted to another electrode. For current to flow between the electrodes, a potential difference must exist between them. Therefore, at least one pair of first and second electrodes may include a positive electrode and a negative electrode, but it is also possible to provide, for example, a positive or negative electrode and a zero-potential electrode.

[0013] The term "ionizing fluid" is understood herein to encompass plasmas containing both positively and negatively charged particles. The term "ionizing fluid" should be further understood to encompass ionized gases and ionized liquids, as well as fluids containing charged particles of solid matter, such as nanoparticles or microparticles.

[0014] Optionally, at least one ionization device can be configured to generate a first ionized fluid volume extending at least from a first solid electrode portion to the surface of the mineral matrix and a second ionized fluid volume extending at least from a second solid electrode portion to the surface of the mineral matrix, the first ionized fluid volume being isolated from the second ionized fluid volume to allow a high-voltage current pulse to pass through the first ionized fluid volume, the mineral matrix, and the second ionized fluid volume. In this case, mechanical contact between either of the solid electrode portions and the mineral matrix is ​​not required, thus further reducing electrode wear. Consequently, the electrode becomes more robust and less expensive. The isolation between the first and second ionized fluid volumes can be achieved, for example, by supplying a shielding fluid (such as a liquid) with a relatively poor conductivity compared to the ionized fluid volume and the solid electrode portion. The shielding fluid can be, for example, a flushing fluid, such as water or even brine.

[0015] Alternatively, the second solid electrode portion can be configured to mechanically press against the mineral matrix, wherein at least one ionizing fluid volume is isolated from the second solid electrode portion. Mechanically pressing the second solid electrode portion against the mineral matrix facilitates the proper positioning of the first solid electrode portion relative to the mineral matrix, i.e., positioning it at a distance that will provide optimal conditions for generating the ionizing fluid volume. As explained above, isolation between the ionizing fluid volume and the second solid electrode portion can be achieved.

[0016] Optionally, at least one ionization device includes at least one plasma generator, and the drilling tool further includes:

[0017] - Compressed gas supply system for supplying compressed gas to at least one plasma generator.

[0018] At least one plasma generator is configured to ionize compressed gas to produce plasma, and at least one ionized fluid volume is formed by the plasma. Therefore, in this context, the term "ionized fluid" refers to plasma. The plasma generator, for example, can be of the type sometimes called a plasma torch or plasma tube, producing a stable volume of ionized fluid from a compressed gas supply source. In particular, plasma tubes / plasma torches efficiently produce a stable and continuous plasma flow in any gas. The compressed gas can be compressed air or a compressed inert gas, such as argon (Ar). Inert gases generally provide a more stable plasma, which is useful for relatively large distances between the solid electrode section and the mineral matrix. On the other hand, compressed air can be easily and continuously formed using a compressor, which does not require collection and recirculation after use, and works well for relatively short distances between the solid electrode section and the mineral matrix.

[0019] Plasma generators allow the ionization level of the generated plasma to be controlled at orders of magnitude and within nanoseconds. Therefore, the plasma's properties, including conductivity and inductance, can be readily tuned to meet the needs of optimized current pulse transmission to the mineral matrix. This is particularly important for fast and ultrafast pulses, in which most of the pulse energy is attributed to electromagnetic waves traveling along the electrodes. For any given ionization level of the plasma, by applying an external magnetic field that forces the plasma's electrons into a helical trajectory, the plasma's inductive behavior can be controlled at least an order of magnitude. Therefore, the plasma itself can be used as a means of impedance matching high-voltage current pulses, ensuring that most of the pulse energy is delivered to the mineral matrix without being lost elsewhere.

[0020] As an alternative to providing a plasma generator for generating an ionized fluid volume, an ultraviolet (UV) pulse source or a gamma source, such as an X-ray source, can be provided to generate ionizing radiation pulses. Further, a thermo-ionization device for the thermal generation of ions can be provided, or a pre-discharge from a pulsed power generator can be used to generate the ionized fluid volume.

[0021] Optionally, at least one plasma generator includes a low-voltage power supply arranged separately from the pulse power generator.

[0022] Optionally, at least the first electrode includes a first plasma generator, and more optionally, the second electrode includes a second plasma generator. Therefore, for an electrode pair in which an ionized fluid volume is generated between the first and second solid electrode portions and the mineral matrix, respectively, the first and second electrodes may include their own plasma generators. For an electrode pair in which the second solid electrode portion is configured to be mechanically applied to the mineral matrix, a single plasma generator may be provided within the first electrode. In drilling tools comprising multiple electrode pairs, plasma generators may be included in one or both electrodes of each electrode pair.

[0023] Optionally, each plasma generator includes a housing electrically connected to a pulsed power generator and further electrically connected to a solid electrode portion of an electrode in which the plasma generator is disposed. This allows a high-voltage current pulse to be transmitted from the pulsed power generator through the housing and the solid electrode portion to the plasma.

[0024] Alternatively, as an alternative, at least one plasma generator is arranged upstream of the electrode, configured to supply plasma to at least the first electrode and optionally to the second electrode. A high-voltage current pulse is coupled to the plasma at a solid electrode portion of the electrode, which is not electrically connected to the plasma generator. Thus, the electrode is positioned between the plasma generator and the mineral matrix, allowing plasma to flow from the plasma generator, through the electrode, and to the mineral matrix. In this configuration, a single plasma generator can be used to supply plasma to multiple electrodes.

[0025] Optionally, the pulsed power drilling tool further includes at least one shielding member configured to prevent high-voltage current pulses generated by the pulsed power generator from passing through the generated plasma to at least one plasma generator. One or more such shielding members may be provided, for example, within an insulating housing of the plasma generator, in which conduits are provided for allowing plasma to flow from the plasma generator to one or more electrodes. The one or more shielding members may, for example, include a series of corrugations or other surface structures provided in the inner wall of the insulating housing defining the conduits, which prevent the high-voltage current pulses from traveling "backward" through the plasma.

[0026] Optionally, the pulsed power drilling tool further includes a fluid supply system for supplying a shielding fluid to the area between the drill bit and the mineral matrix. The shielding fluid can be any fluid that can be used to shield one or more ionized fluid volumes from each other and / or from one or more solid electrode portions of one or more other electrodes. The shielding fluid can preferably be a fluid different from the ionized fluid volumes. The shielding fluid can be, for example, a flushing liquid, such as water, which is typically supplied during drilling operations.

[0027] Optionally, the drill bit includes at least one contact member projecting in the axial direction of the drilling tool relative to at least the first solid electrode portion. The contact member may be arranged to provide a suitable distance between at least the first solid electrode portion and the mineral matrix. It may be, for example, the solid electrode portion, a scraper, or another device.

[0028] Optionally, the drilling tool includes a positioning device for controlling the distance between at least the first solid electrode portion and the surface of the mineral matrix. The positioning device may, for example, include a sensor for measuring the distance between the solid electrode portion and the mineral matrix, and a device for automatically adjusting the distance to a target value by adjusting the position of the drill bit. Typically, the target value can be set to a distance of at least 1 mm, or at least 2 mm, or at least 3 mm, and not exceeding 5 cm, or not exceeding 2 cm, or not exceeding 1 cm. Preferably, the target value can be in the range of 1-5 mm, such as 2-5 mm. The target value can be set according to the borehole size, the surface roughness of the mineral matrix, the ionizing fluid flow rate and characteristics, the electrode diameter, etc. Ideally, the distance from the surface should be set such that a stable ionizing fluid volume is achieved at least during the pulse duration of the high-voltage current pulse.

[0029] The positioning device may include, for example, means for performing impedance analysis, wherein the positioning device is configured to automatically position the drill bit to meet impedance criteria, such as to achieve an impedance below a predetermined threshold.

[0030] Optionally, the drill bit includes multiple scrapers arranged between the electrodes. In this case, the drilling tool should be rotatable about its longitudinal axis. In other embodiments without scrapers, the drilling tool does not need to rotate about its longitudinal axis.

[0031] According to a second aspect of this disclosure, at least the primary objective is achieved by a method for breaking up a mineral matrix. This method is performed by passing a pulsed current through the mineral matrix using a pulsed power drilling tool according to the first aspect. The method includes:

[0032] - Position the drill bit so that the solid electrode portion is at least near the surface of the mineral matrix.

[0033] - Generate at least one ionized fluid volume.

[0034] - Generate a high-voltage current pulse and make the high-voltage current pulse travel from the first electrode through at least one ionized fluid volume and mineral matrix to the second electrode.

[0035] Depending on the configuration of the drilling tool, the first solid electrode portion can be positioned near the surface of the mineral matrix, and the second solid electrode portion can be positioned near the surface of the mineral matrix or in contact with the surface of the mineral matrix.

[0036] Optionally, generating at least one ionized fluid volume includes ionizing compressed gas to generate plasma, the at least one ionized fluid volume being formed by plasma.

[0037] Optionally, the method further includes:

[0038] - At least during the operation of transmitting a high-voltage current pulse from the first electrode to the second electrode, shielding fluid is supplied to the area between the electrodes. 9 o'clock

[0039] The method according to the second aspect can, of course, be performed using a pulse power drilling tool according to any of the embodiments described above according to the second aspect. Therefore, further advantages and advantageous features of the method become apparent from the above description of the drilling tool.

[0040] This disclosure also relates to the use of the pulse power drilling tool according to the first aspect for breaking mineral matrix, such as in rock drilling, concrete processing, mineral processing and continuous mining.

[0041] Other advantages and advantageous features of this disclosure are disclosed in the following description. Attached Figure Description

[0042] Referring to the accompanying drawings, a more detailed description of embodiments of this disclosure, cited by way of example, follows.

[0043] In the attached diagram:

[0044] Figure 1 A pulse power drilling tool according to an embodiment of the present disclosure is illustrated schematically.

[0045] Figure 2a yes Figure 1 A cross-sectional view of the electrode of the drilling tool in the image.

[0046] Figure 2b This is a cross-sectional view of an electrode pair for a drilling tool according to an embodiment of the present disclosure.

[0047] Figure 3 This is a cross-sectional view of an electrode pair for a drilling tool according to another embodiment of the present disclosure.

[0048] Figure 4 A flowchart illustrating the steps of the method according to this disclosure, and

[0049] Figure 5 It includes Figure 1 The rock drill shown is a drilling tool.

[0050] The accompanying drawings illustrate illustrative and exemplary embodiments of the present disclosure and are therefore not necessarily drawn to scale. It should be understood that the illustrated and described embodiments are exemplary and that the present disclosure is not limited to these embodiments. It should also be noted that some details in the drawings may be exaggerated for better description and illustration of the present disclosure. The same reference numerals refer to the same elements throughout the description unless otherwise stated. Detailed Implementation

[0051] Figure 1A pulsed power drilling tool 100 is schematically illustrated, which is configured to pass a pulsed current through a mineral matrix 400 to break it. The drilling tool 100 has a pulsed power generator 110 for generating high-voltage current pulses, and a drill bit 120 extending in the axial direction of the drilling tool 100 between a front end 121 and a rear end 122, the front end 121 being configured to be located near or at the surface of the mineral matrix 400.

[0052] The pulse power generator 110 includes a pulse transformer 112 in the form of a capacitor bank connected to an alternating current (AC) power supply 113 via a transformer 111. Electrodes 200 and 200' are selected and connected using switches 114 and 114'. Short, high-voltage pulses are generated using switches 114 and 114'. The pulse power generator is configured to generate pulses, such as nanosecond (ns) pulses, for breaking up the mineral matrix 400 at electrodes 200 and 200'.

[0053] A pair of first electrodes 200 and second electrodes 200' are arranged at the front end 121 of the drill bit 120, protruding slightly from the front end 121. See also... Figure 2a This shows a schematic cross-sectional view of the first electrode 200 arranged near the mineral matrix 400. Figure 1 In the embodiment shown, the second electrode is the same as the first electrode 200, so only the first electrode 200 will be described in detail.

[0054] The first electrode 200 includes a hollow first solid electrode portion 201 disposed at the front end of the electrode 200. The solid electrode portion 201 is shown here as threaded, thus allowing for replacement. It is at least partially made of a conductive material and can be metal or ceramic. At least a portion must be heat-resistant and capable of carrying plasma return current. For example, the solid electrode portion 201 can be made of tungsten, stainless steel, aluminum, copper, or zirconium oxide ceramic. An insulating protective sheath 202 is provided on the outer surface of the solid electrode portion 201 to protect it from direct contact with the environment surrounding the electrode 200.

[0055] The first electrode 200 further includes an ionization device in the form of a plasma generator 220. The plasma generator 220 is configured to generate a first ionizing fluid volume 210 in the form of plasma, which extends from the first electrode 200 to the surface of the mineral matrix 400. A compressed gas supply system 130 is provided to supply compressed gas to the plasma generator 220 of each electrode 200, 200' (although in... Figure 1The diagram only shows the supply to the first electrode 200, such as compressed air. The plasma generator 220 ionizes the compressed gas to generate plasma. This can be done using standard procedures. For example, gas from the compressed gas supply system 130 can initially pass through a pre-ionization stage, where a low-power, high-voltage source (typically 50 kV) generates a series of weak sparks that create some conductive pairs in the gas. Pre-ionization can also be achieved using, for example, ultraviolet (UV) light. The pre-ionized gas then proceeds to the ionization stage.

[0056] In the illustrated embodiment, the plasma generator 220 uses a low-voltage power supply 225 during the ionization phase, which is separately arranged from the pulsed power generator 110. The low-voltage power supply 225 is electrically connected on one hand to the conductive housing 221 of the plasma generator 220, which defines a cavity for ionizing gas, and on the other hand to a conical plasma tube electrode 222 spaced apart from the housing 221 by a gap, typically several millimeters depending on the gas flow rate. Pre-ionized gas enters the gap, where an electric field accelerates conductive particles, resulting in the generation of more than one charged particle upon collision with charged and uncharged particles. This thus forms an avalanche process. The low-voltage power supply 225 can be a direct current (DC) or a slow AC power supply. Typically, a drive voltage of 50-100 V and a current up to several amperes can be used, depending on the gas flow rate and electrode geometry.

[0057] In an alternative embodiment, the plasma generator may use voltage and current pulses from pulsed power generator 110 to generate plasma during the ionization phase. A series of pulses with different pulse lengths and voltages may be used for this purpose. For example, a pilot pulse with a lower voltage and longer duration than the main pulse used to break up the mineral matrix 400 may be used to generate plasma, such as a millisecond pulse preceding the nanosecond pulse used to break up the mineral matrix 400.

[0058] In another alternative embodiment, the plasma generator may utilize a magnetron attached to a microwave resonator during the ionization phase. In this case, pre-ionized gas enters the microwave resonator, which may be, for example, a cavity formed within electrodes, and a set of resonator modes and at least one traveling wave mode are generated within the cavity. The traveling wave mode accelerates charged particles, causing collisions that induce an avalanche process.

[0059] The solid electrode portions of the first electrode 200 and the second electrode 200' can be electrically connected to the pulse power generator 110 via switches 114 and 114'. Figure 2aIn the illustrated embodiment, this is achieved by electrically connecting the conductive housing 221 to the solid electrode portion 201 and then to the switch 114, such that a high-voltage current pulse 150 generated by the pulse power generator 110 passes through the housing 221 and reaches the solid electrode portion 201, where a discharge is formed between the solid electrode portion 201 and the mineral matrix 400 via the first ionizing fluid volume 210. When the switches 114, 114' are closed, the high-voltage current pulse 150 then passes through the first ionizing fluid volume 210, the mineral matrix 400, and the second ionizing fluid volume 210' between the first solid electrode portion 201 of the first electrode 200 and the second solid electrode portion 200' of the second electrode. As a result, a plasma channel is formed in the mineral matrix 400, and the mineral matrix 400 is broken up.

[0060] The drilling tool 100 further includes a fluid supply system 140 for supplying a shielding fluid, such as a flushing fluid (e.g., water), to the area between the drill bit 120 and the mineral matrix 400 via a fluid conduit 141 having an outlet 142 located between a first electrode 200 and a second electrode 200'. The flushing fluid isolates a first ionizing fluid volume 210 from a second ionizing fluid volume 210'. An insulating protective sheath 202 protects the solid electrode portion 201 from direct contact with the environment surrounding the electrode 200. The plasma generator 220 also has an insulating sheath or coating 223 provided on its outer surface to protect the conductive housing 221 from direct contact with the flushing fluid.

[0061] Figure 2b An alternative electrode arrangement is shown, wherein the electrode pairs of the drilling tool 100 include those shown in the reference. Figure 2a The plasma-generating first electrode 200 and solid second electrode 200'' are described, the solid second electrode 200'' including a solid electrode portion 201'' configured to mechanically press against a mineral matrix 400. A first ionizing fluid volume 210 is isolated from the second solid electrode portion 201'', such that a high-voltage current pulse 150 passes between the first ionizing fluid volume 210 and the mineral matrix 400 and the first solid electrode portion 201'' and the solid second electrode 200''.

[0062] Figure 1 The drilling tool 100 of the type shown may include multiple electrode pairs, some of which may include two plasma-generating electrodes 200, and some of which may include a solid electrode 200''.

[0063] Figure 3Another alternative electrode arrangement is shown, in which a pair of first electrodes 300 and second electrodes 300' share a common plasma generator 320 disposed upstream of electrodes 300, 300'. The common plasma generator 320 can be shared by several electrode pairs, although only one pair is illustrated. The common plasma generator 320 can also be used to generate plasma and supply plasma to the first electrodes of multiple electrode pairs, and the common plasma generator can be combined with... Figure 2b The solid second electrode 200'' assembly is illustrated in the figure.

[0064] Plasma generator 320 is positioned downstream of compressed gas supply system 130, such that compressed gas is supplied to plasma generator 320, ionized to form plasma, and supplied to each of the two electrodes 300, 300'. Plasma generator 320 is connected to a reference... Figure 2a The plasma generators described are of the same type, namely, they include a low-voltage power supply 325, a conductive housing 321, and a conical plasma tube electrode 322 spaced apart from the housing 321.

[0065] Electrodes 300 and 300' each include a reference Figure 2a Solid electrode portions 301 and 301' of the same type as the described solid electrode portions are insulated by insulating protective sheaths 305 and 305'. However, solid electrode portions 301 and 301' are here mounted to an insulating housing 303, which encloses the plasma generator 320 and the plasma conduits 304 and 304' leading from the plasma generator to the first solid electrode portion 301 and the second solid electrode portion 301', respectively. The insulating housing 303 thus separates the conductive housing 321 from the solid electrode portions 301 and 301'. The insulating housing 303 also includes shielding members 302 and 302', which are configured to prevent high-voltage current pulses generated by the pulse power generator 110 from traveling backward through the generated plasma into the plasma generator 320 and / or between the solid electrode portions 301 and 301' without penetrating the mineral matrix 400. The shielding members 302 and 302' are here formed by a series of corrugations provided in the inner wall of the insulating housing 303. The plasma generator 320 generates plasma, which forms a first ionized fluid volume 310 extending between the first solid electrode portion 301 and the mineral matrix 400 and a second ionized fluid volume 310' extending between the second solid electrode portion 301' and the mineral matrix 400.

[0066] The solid electrode portions 301, 301' of the first electrode 200 and the second electrode 200' can be electrically connected to the pulse power generator 110 via switches 114, 114'. Therefore, when switches 114, 114' are closed, a high-voltage current pulse 150 passes through the first ionizing fluid volume 310, the mineral matrix 400, and the second ionizing fluid volume 310' between the first solid electrode portion 301 of the first electrode 300 and the second solid electrode portion 301' of the second electrode 300'. As a result, a plasma channel is formed in the mineral matrix 400, and the mineral matrix 400 is broken up.

[0067] As referenced above Figure 1 As described, the shielding fluid can be supplied to the area between electrodes 300 and 300'.

[0068] The same drilling tool 100 can be used as a reference. Figure 2a , Figure 2b and Figure 3 The described combination of electrodes. A drilling tool may include multiple electrode pairs arranged around the periphery of the drill bit 120. As an example, the outlet 142 of the shielded fluid conduit 141 may be located at the center of the drill bit 120, but various different configurations are possible.

[0069] In the illustrated embodiment, the solid electrode portions 201, 301, 301' are protected from the shielding fluid by both the insulating protective sheaths 202, 305, 305' and the ionized fluid volumes 210, 310, 310'. The lack of contact between the solid electrode portions 201, 301, 301' and the flushing fluid results in less volume loss and improved efficiency.

[0070] Although reference Figure 2a , Figure 2b and Figure 3 The solid electrode portions described are hollow, but they can also be non-hollow, similar to... Figure 2b The solid second electrode 200'' is illustrated in the diagram. In that case, the solid electrode portion is immersed in the ionizing fluid. In that case, a hollow insulating shell, such as a tubular shell, is also provided to form the outer shell of the electrode. The solid electrode portion immersed in the ionizing fluid (such as plasma) transmits current pulses to the plasma. Since the solid electrode portion is not intended to mechanically contact the mineral matrix 400 and transmit current via the contact interface, the solid electrode portion including the tip can be designed and optimized for current transmission between the tip and the ionizing fluid, regardless of the mechanical strength of the tip.

[0071] Back Figure 1The drill bit 120 may further include one or more contact members (not shown) that project in the axial direction of the drilling tool 100 relative to at least the first solid electrode portions 201, 301, i.e., from the front end 121 of the drill bit 120. Alternatively, the drilling tool 100 may include a positioning device (not shown) for controlling the distance between at least the first solid electrode portion 201 and the surface of the mineral matrix 400.

[0072] The drilling tool may further include an electronic control unit 160 for controlling the operation of the drilling tool 100 in response to signals received from an external control unit 170, such as a control unit of the machine to which the drilling tool is provided. The electronic control unit 160 may include a microprocessor, microcontroller, programmable digital signal processor, or other programmable device. Therefore, the control unit 160 includes electronic circuitry and connections (not shown) for communicating with different parts of the drilling tool 100 and with the external control unit 170, as well as processing circuitry (not shown). For example, the control unit 160 may be configured to communicate with various sensors, devices, systems, and control units of the drilling tool 100. In the illustrated embodiment, the control unit 160 controls the transformer 111 and switches 114, 114'. Although not shown, the control unit 160 may also be used to control at least one ionization device, fluid supply system 140, and / or compressed gas supply system 130. Alternatively, several independent control units may be provided.

[0073] The electronic control unit 160 may include modules, or partially modules, in hardware or software, and communicate using known transmission buses such as the CAN bus and / or wireless communication capabilities. The processing circuitry may be a general-purpose processor or a dedicated processor. The control unit 160 may include non-transitory memory for storing computer program code and data. Therefore, those skilled in the art will recognize that the electronic control unit 160 can be embodied in many different configurations.

[0074] Figure 4 The example illustrates a method for breaking a mineral matrix 400 by passing a pulsed current through it using the pulsed power drilling tool 100 described above. This method includes the following actions:

[0075] S1: Positioning drill bit 120 such that the solid electrode portion is at least near the surface of mineral matrix 400. When the drilling tool 100 includes a combination of solid electrode 200'' and plasma-generating electrodes 200, 300, 30', the solid electrode can be arranged to contact the surface of mineral matrix 400, with the remaining electrodes positioned near the surface.

[0076] S2: For example, generating plasma by using one or more plasma generators 220, 320 to generate at least one ionized fluid volume 210, 210', 310, 310'.

[0077] S3: Generate a high-voltage current pulse 150 and transfer it from the first electrodes 200, 300 to the second electrodes 200', 200'' via at least one ionized fluid volume 210, 210', 310, 310' and mineral matrix 400.

[0078] The method may also include the optional step of supplying a shielding fluid to the region between electrodes 200, 200', 200'', 300, 300' at least during the operation of transmitting a high-voltage current pulse from the first electrodes 200, 300 to the second electrodes 200', 200'', 300'. Preferably, the shielding fluid is supplied continuously.

[0079] Figure 5 A rock drill 500 is schematically illustrated, which includes a drill for drilling holes 401 in a mineral matrix 400 in the form of rock. Figure 1 The drilling tool 100 is shown. The rock drill 500 includes an alternating current (AC) power supply 113 for powering a pulse power generator 110 and plasma generators 220, 320. It further includes a compressed gas supply system 130 and a fluid supply system 140. A hydraulic, pneumatic, or electric arm 510 is provided for at least vertical positioning of the drilling tool 100, the arm 510 responding to signals from one or more position sensors (not shown) or similar signals sensing the distance between an electrode and the surface of the mineral matrix. The rock drill 500 further includes a ground engagement member 520 for moving the rock drill 500 in a direction parallel to the rock 400.

[0080] It should be understood that this disclosure is not limited to the embodiments described above and illustrated in the accompanying drawings; rather, those skilled in the art will recognize that many changes and modifications can be made within the scope of the appended claims.

Claims

1. A pulsed power drilling tool (100) configured to pass a pulsed current through a mineral matrix (400) to break the mineral matrix (400), the drilling tool (100) comprising: - Pulse power generator (110) is used to generate high-voltage current pulses. - A drill bit (120) includes at least one pair of first electrodes (200, 300) and second electrodes (200', 200'', 300'), the first electrodes (200, 300) including a first solid electrode portion (201, 301), and the second electrode including a second solid electrode portion (201'', 301'), the first solid electrode portion (201, 301) and the second solid electrode portion (201'', 301') being electrically connected to the pulse power generator (110), and - At least one ionization device is configured to generate at least one ionized fluid volume (210, 310, 210', 310') extending at least from the first solid electrode portion (201, 301) to the surface of the mineral matrix (400) so as to allow a high-voltage current pulse (150) to pass between the first solid electrode portion (201, 301) and the second solid electrode portion (201, 301, 201', 301') via the at least one ionized fluid volume (210, 310, 210', 310') and the mineral matrix (400).

2. The pulsed power drilling tool of claim 1, wherein the at least one ionization device is configured to generate a first ionized fluid volume (210, 310) extending at least from the first solid electrode portion (201, 301) to the surface of the mineral matrix (400) and a second ionized fluid volume (210', 310') extending at least from the second solid electrode portion (301') to the surface of the mineral matrix (400), the first ionized fluid volume (210, 310) being isolated from the second ionized fluid volume (210', 310') to allow the high-voltage current pulse (150) to pass through the first ionized fluid volume (210, 310), the mineral matrix, and the second ionized fluid volume (210', 310').

3. The pulse power drilling tool according to claim 1, wherein the second solid electrode portion (201'') is configured to mechanically press against the mineral matrix (400), and wherein the at least one ionized fluid volume (210) is isolated from the second solid electrode portion (201'').

4. The pulsed power drilling tool according to any one of claims 1-3, wherein the at least one ionization device comprises at least one plasma generator (220, 320), and wherein the drilling tool further comprises: - A compressed gas supply system (130) for supplying compressed gas to the at least one plasma generator (220, 320), The at least one plasma generator (220, 320) is configured to ionize the compressed gas to generate plasma, and the at least one ionized fluid volume (210, 310, 210', 310') is formed by the plasma.

5. The pulsed power drilling tool according to claim 4, wherein the at least one plasma generator (220, 320) includes a low-voltage power supply (225, 325) arranged separately from the pulsed power generator (110).

6. The pulsed power drilling tool according to claim 5, wherein at least the first electrode (200) includes a first plasma generator (220), and optionally, wherein the second electrode (200') includes a second plasma generator.

7. The pulse power drilling tool according to claim 6, wherein each plasma generator (220) includes a housing (221) electrically connected to the pulse power generator (110) and further electrically connected to the solid electrode portion (201) of the electrode (200), the plasma generator (220) being disposed in the electrode (200).

8. The pulsed power drilling tool according to claim 5, wherein the at least one plasma generator (320) is disposed upstream of the electrodes (300, 300'), the at least one plasma generator (320) being configured to supply plasma to at least the first electrode (300) and optionally to the second electrode (300').

9. The pulsed power drilling tool according to claim 8, further comprising at least one shielding member (302, 302') configured to prevent the high-voltage current pulse generated by the pulsed power generator (110) from traveling through the generated plasma to the at least one plasma generator (320).

10. The pulse power drilling tool according to any one of claims 1-3 and 5-9, further comprising a fluid supply system (140) for supplying shielding fluid to the region between the drill bit (120) and the mineral matrix (400).

11. The pulse power drilling tool according to any one of claims 1-3 and 5-9, wherein the drill bit (120) includes at least one contact member protruding in the axial direction of the drilling tool (100) relative to at least the first solid electrode portion (201, 301), and / or wherein the drilling tool (100) includes a positioning device for controlling the distance between at least the first solid electrode portion (201, 301) and the surface of the mineral matrix (400).

12. A method for breaking a mineral matrix (400) by passing a pulsed current through it using a pulsed power drilling tool (100) according to any one of claims 1-11, the method comprising: - Position (S1) the drill bit (120) such that the solid electrode portions (201, 301, 201'', 301') are at least near the surface of the mineral matrix (400). - Generate (S2) at least one ionized fluid volume (210, 310, 210', 310'). - Generate a high-voltage current pulse (150) and transfer the high-voltage current pulse (150) from the first electrode (200, 300) via the at least one ionized fluid volume (210, 310, 210', 310') and the mineral matrix (400) to the second electrode (200', 200'', 300').

13. The method of claim 12, wherein generating the at least one ionized fluid volume (210, 310, 210', 310') comprises ionizing compressed gas to generate plasma, the at least one ionized fluid volume (210, 310, 210', 310') being formed by the plasma.

14. The method according to claim 12 or 13, further comprising: - At least during the operation of transmitting the high-voltage current pulse (150) from the first electrode (200, 300) to the second electrode (200', 200', 300'), shielding fluid is supplied to the region between the electrodes (200, 300, 200', 200'', 300').

15. Use of the pulse power drilling tool (100) according to any one of claims 1-11 for breaking mineral matrix (400) in any one of rock drilling, concrete processing, mineral processing and continuous mining.

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