Tiered-discharge electric grinder for rocky material

Abstract

The invention relates to a grinder (1) comprising a grinding chamber, at least one first positioning element (21) made of an electrically insulating material, at least one second positioning element (22) made of an electrically insulating material and having dimensions smaller than the dimensions of the first positioning element (21), in order to form a second filtering space, and at least one pair of electrodes comprising a first electrode (10) and a second electrode (31) arranged facing one another on either side of the second filtering space.

Description

Electric step-discharge crusher for rock material

[0001] The present invention relates to the field of rock crushing and more particularly concerns a rock material crusher and a method of crushing rock material by electric discharge.

[0002] It is known to crush rock to extract metals such as copper. Such extraction can be carried out purely mechanically or, more efficiently, by high-voltage electrical discharges.

[0003] In mechanical solutions, it is necessary to completely crush the rock material to transform it into rock powder and be able to extract the metal, which can be particularly long and require a very large amount of energy.

[0004] In electrical solutions, discharges break the rock into smaller and smaller pieces until the metal can be extracted.

[0005] For example, patent application EP3261768A1 describes a device comprising electrodes arranged above a belt. However, such a solution does not allow the rocks to be sorted according to their dimensions and it is then necessary to pass the pieces over the belt several times to obtain sufficient granularity, which can be time-consuming and costly, particularly in terms of energy.

[0006] Patent application WO99 / 03588 describes a gravity-guided grinding process which can, however, still require significant energy and time.

[0007] Other solutions exist, for example described in documents JP11033430, EP2691180A1, DE102014008989, WO20200120437, but they do not allow the rock to be crushed efficiently.

[0008] The solution described in patent application GB2421203 describes an interesting solution for crushing increasingly smaller rocks, but has several drawbacks. Due to the oblique configuration of the electrodes, approximately at 45°, pieces of rock that cannot pass through the space between the electrodes of a pair of electrodes become stuck on the electrodes but may not reach the space between the electrodes. Also, during an electrical discharge, the current will pass through the shortest path in the void under a piece of rock, which will not allow it to be fragmented and will block the device, then requiring the intervention of an operator to clean the crusher.

[0009] US patent application US 2021 / 069724 A1 describes a rock crusher comprising a crushing chamber, a pair of electrodes, and a generator. The crusher filters the material according to size but does not allow for the fragmentation of all rock elements, which can again block the device, requiring an operator to clean the crusher.

[0010] There is therefore a need for a simple and effective solution to at least partially overcome these drawbacks.

[0011] For this purpose, the invention firstly relates to a rock material crusher by electric discharge, said crusher comprising:

[0012] - a crushing chamber comprising at least one side wall defining an internal space, an upper face through which the rock material is introduced and a lower face through which the crushed rock material is collected,

[0013] - at least one first positioning element, made of an electrically insulating material, mounted in the internal space at the lower face of the chamber and positioned so as to form a first filtering space for discharging crushed rock material through the lower face of the chamber, said at least one first positioning element comprising on its upper surface, along the first filtering space, a support portion configured to support rock material,

[0014] - at least one second positioning element, made of an electrically insulating material and whose dimensions are smaller than the dimensions of a first positioning element, each second positioning element having a free edge and being mounted in the internal space above a first positioning element so that said free edge delimits a second filtering space extending above the support portion of the first positioning element located below and as far as the first filtering space, the free edge of the second positioning element and the support portion of the first positioning element located below thus making it possible to position rock material in said second filtering space,

[0015] - at least one pair of electrodes comprising a first electrode and a second electrode, arranged face to face on either side of the second filtering space,

[0016] - at least one generator configured to apply a voltage between the first electrode and the at least one second electrode so as to cause an electrical discharge to grind the rock material elements positioned in the second filtering space and thus allow at least a portion of the crushed rock material to pass into the first filtering space to be collected.

[0017] The electric step-discharge crusher according to the invention makes it possible to crush rock efficiently thanks to the positioning elements which make it possible to position the rock material in the filter spaces according to their size between the first electrode and the second electrode of a pair of electrodes. The use of several filter spaces of increasing finer size makes it possible to obtain crushed material of increasing finer size from top to bottom, until the desired size is obtained at the outlet through the first filter space.

[0018] According to one aspect of the invention, the first electrode and the second electrode of a pair of electrodes are configured to generate an electric arc in the filtering space around which they are placed when a voltage is applied between said first electrode and said second electrode.

[0019] In one embodiment, the at least one first electrode is an anode and the at least one second electrode is a cathode.

[0020] In another embodiment, the at least one first electrode is a cathode and the at least one second electrode is an anode.

[0021] Advantageously, the crusher comprises more than two positioning elements each made of an electrically insulating material and stacked one above the other, the dimensions of an upper positioning element being smaller than the dimensions of the immediately lower positioning element so as to form a filtering space of width greater than the width of the at least one filtering space formed by the immediately lower positioning element and opening onto said filtering space formed by the immediately lower positioning element.

[0022] In one embodiment, the electrodes, in particular the second electrode(s), are mounted between two positioning elements in a so-called “inter-element” space, extending radially in the internal space.

[0023] In another embodiment, at least a portion of the electrodes, including the second electrode(s), is mounted in a positioning member extending radially into the internal space.

[0024] Advantageously, the at least one second electrode may be a single entirely metallic electrode, for example in the form of a disc, or may comprise an electrical insulator comprising one or more metallic electrodes.

[0025] Alternatively or additionally, the at least one second electrode may comprise several electrodes each having an elongated shape and extending radially while being equally distributed around the longitudinal axis of the stack.

[0026] In one embodiment, the at least one first electrode and the at least one second electrode are linear, for example in the form of a rod.

[0027] In one embodiment, the grinder comprises a single first electrode of cylindrical shape, preferably of circular or polygonal (e.g., square or hexagonal) section.

[0028] In one embodiment, the positioning elements are mounted around the first electrode and the filter spaces are formed against the outer wall of said first electrode.

[0029] Advantageously, in this embodiment, the positioning elements are cylindrical in shape and arranged coaxially with the first electrode.

[0030] Advantageously, still in this embodiment, the crusher comprises a truncated cone-shaped element pierced in its center, mounted in the upper part of the chamber in order to direct the rock material introduced into the chamber towards the filtering spaces.

[0031] In another embodiment, the positioning elements are mounted within the first electrode and the filter spaces are formed against the inner wall of said first electrode.

[0032] Advantageously, in this embodiment, the positioning elements are cylindrical in shape and arranged coaxially with the first electrode.

[0033] Advantageously, still in this embodiment, the crusher comprises a conical element mounted on the highest positioning element in order to direct the rock material introduced into the chamber towards the filtering spaces.

[0034] Advantageously, still in this embodiment, the side wall of the chamber comprises the first electrode or constitutes the first electrode.

[0035] In another embodiment, the at least one first electrode and the at least one second electrode are linear, for example in the form of a metal rod.

[0036] Advantageously, in this embodiment, the positioning elements are rectangular in shape.

[0037] Advantageously, the crusher comprises in its upper part at least one fluid inlet configured to deliver a flow of fluid in order to convey the pieces of rock material through the successive filtering spaces according to their size to crush them and then evacuate them.

[0038] Preferably, the width of each filtering space is adapted to the size of the rocks to be crushed so as to ensure the positioning of the rocks between the electrodes before crushing and the evacuation of the rocks after crushing according to the desired final size.

[0039] Preferably, the width of the first filtering space is less than 5 mm, more preferably less than 3 mm, more preferably less than 2 mm, for example to recover fine rock powder which may for example contain a large proportion of ore.

[0040] Advantageously, the portions of material delimiting a filtering space can extend radially or axially or form an elbow or a slope, for example at 45°, to filter the pieces of rock.

[0041] In one embodiment, the filtering space(s) of a stage are formed in the positioning element of said stage or in an electrically insulating support inserted in a dedicated space.

[0042] Preferably, the grinder comprises a collector fixed under the bottom of the grinder so that the first filter space opens into said collector.

[0043] In one embodiment, the crusher further comprises at least one presence sensor configured to detect the presence of rock material between the first electrode and the at least one second electrode.

[0044] In one embodiment, the grinder is configured to automatically control a series of electrical discharges between at least one pair of electrodes.

[0045] Advantageously, the crusher being configured to automatically control a series of electrical discharges between at least one pair of electrodes at a frequency of between one and a few hundred Hertz, up to 1000 Hertz.

[0046] The invention also relates to a method for crushing rock material by electric discharge, said method, implemented by a crusher as presented previously arranged vertically in the position of use, comprising the steps of:

[0047] - introduction of rock material through the upper face of the chamber,

[0048] - positioning rock material at least in the filtering space defined by the uppermost positioning element between the electrodes of at least one pair of electrodes, said rock material being supported by the support portion of the positioning element located immediately below the uppermost positioning element,

[0049] - triggering at least one electrical discharge at each stage, preferably a succession of discharges, from a voltage supplied by the at least one generator in order to crush the rock material positioned between said electrodes of each stage,

[0050] - conveying of increasingly fine rock material through successive filtering spaces from top to bottom,

[0051] - evacuation of the crushed material through the first filtering space, preferably towards a collector fixed under the lower face of the chamber.

[0052] Advantageously, the method comprises introducing a fluid, for example water, through the upper face of the chamber during crushing in order to circulate the pieces of rock material easily through the filter spaces.

[0053] Advantageously, the method also comprises a step of detecting rock material by a detection sensor in at least one of the filtering spaces between the first electrode and a second electrode and applying a voltage to the terminals of the first electrode and said second electrode in order to trigger at least one crushing discharge.

[0054] Other characteristics and advantages of the invention will become apparent from reading the description which follows. This description is purely illustrative and must be read in conjunction with the appended drawings in which:

[0055] Diagrammatically illustrates in perspective an embodiment of the crusher according to the invention.

[0056] This is a partial top perspective view of the grinder without a cover.

[0057] This is a partial perspective view of the mill without cover, side wall and first electrode.

[0058] This is a longitudinal sectional view of the crusher.

[0059] This is a schematic view in longitudinal section of a first example of a first type of arrangement, with central filtering, of the grinder 1 according to the invention.

[0060] This is a schematic cross-sectional view of a circular shape of the crusher.

[0061] This is a schematic cross-sectional view of a square-shaped crusher.

[0062] This is a schematic view in longitudinal section of a second example of the first type of arrangement, with central filtering, of the grinder 1 according to the invention.

[0063] This is a schematic view in longitudinal section of a third example of the first type of arrangement, with central filtering, of the grinder 1 according to the invention.

[0064] This is a schematic view in longitudinal section of a first example of a second type of arrangement, with peripheral filtering, of the grinder 1 according to the invention.

[0065] This is a schematic view in longitudinal section of a second example of the second type of arrangement, with peripheral filtering, of the grinder 1 according to the invention.

[0066] This is a schematic view in longitudinal section of a third example of the second type of arrangement, with peripheral filtering, of the grinder 1 according to the invention.

[0067] This is a schematic view in longitudinal section of an example of a third type of arrangement, with linear filtering, of the mill 1 according to the invention.

[0068] This is an enlarged schematic longitudinal sectional view of an angled filter space shape.

[0069] This is an enlarged schematic longitudinal sectional view of an inclined filter space shape.

[0070] This is a schematic perspective view of a positioning element having orifices at its support portion, said orifices forming a plurality of filtering spaces.

[0071] Diagrammatically illustrates an embodiment of the method according to the invention.

[0072] Figures 1 to 4 show an example of a grinder 1 according to the invention and Figures 5 to 13 show different examples of the internal arrangement of the grinder 1 according to the invention.

[0073] Example of figures 1 to 4

[0074] With reference to the, the crusher 1 comprises a crushing chamber 2 provided with a side wall 3, a cover 4, a bottom 5.

[0075] With reference to the, the side wall 3 of the chamber 2 is cylindrical with a circular section and defines an internal space 2A in which a first cylindrical electrode 10, also with a circular section, is placed.

[0076] Chamber 2 comprises an upper face 2B and a lower face 2C ().

[0077] Referring again to the, the side wall 3 has at its upper edge a circular rim 3A allowing the cover 4 to be fixed using screws.

[0078] The cover 4 has a vertical inlet conduit 4A allowing pieces of rock material to be inserted into the chamber 2.

[0079] With reference to figures 2 and 3, the crusher 1 comprises a conical element 6.

[0080] With reference to Figures 3 and 4, the crusher 1 comprises a first positioning element 21, a second positioning element 22, a second electrode 31, a generator (not visible in the example of Figures 1 to 4 but represented in the arrangement examples given below with the reference 40), and a rock powder collector 50.

[0081] The first positioning element 21 is circular in shape, is mounted on the bottom 5 and is made of an electrically insulating material.

[0082] With reference to the, the first positioning element 21 has radial dimensions smaller than the diameter of the first electrode so as to form a first circular filtering space EP1.

[0083] The first filtering space EP1 allows the crushed material to be evacuated through the bottom 5 of the crusher 1 towards the collector 50.

[0084] The second positioning element 22 is made of an electrically insulating material and also has a cylindrical shape with a circular section and a radius smaller than that of the first positioning element 21 so that a portion of the upper surface of the first positioning element 21, designated “support portion” PP1, remains visible and accessible to the pieces of rock which are inserted into the crusher 1.

[0085] The second electrode 31 has the shape of a metal disc with a radius substantially equal to the radius of the second positioning element 22 and is mounted coaxially and integrated into the second positioning element 22 so as to be protected from the rock falling into the second filtering space EP2.

[0086] The free edge 31A of the second electrode 31 thus projects opposite the first electrode 10. The space formed between the first electrode 10 and the second electrode 31, above the support portion PP1, is designated the second filtering space EP2. The second filtering space EP2 is in fluid communication with the first filtering space EP1 to allow the passage of the crushed rock material, depending on its size.

[0087] The generator makes it possible to apply a voltage between the first electrode 10 and the second electrode 31 in order to break and crush the pieces of rock material positioned on the support portion PP1 between the first electrode 10 and the second electrode 31. Once crushed sufficiently finely, the rock is evacuated through the first space EP1.

[0088] Examples of arrangement of figures 5 to 13

[0089] In the examples of Figures 5 to 13, the crusher 1 comprises four positioning elements 21, 22, 23, 24 but could, in other embodiments, comprise two, three or more than four.

[0090] Similarly, the crusher 1 comprises three second electrodes 31, 32, 33 but this number could be different in another embodiment, with at least one second electrode 31. According to one aspect of the invention, there is at least one second electrode 31, 32, 33 per stage from the second positioning element 21 in order to crush rocks of different sizes at each stage, more and more finely.

[0091] Each positioning element 21, 22, 23, 24 is made of an electrically insulating material and has a cylindrical shape with a circular section.

[0092] In the arrangement examples of figures 5 to 13, each pair of consecutive positioning elements 21, 22, 23, 24 is separated by a space called “inter-element” in which a second electrode 31, 32, 33 is mounted. In other words, the second electrodes are mounted between the positioning elements 21, 22, 23, 24.

[0093] In the examples of figures 5 to 13, each second electrode 31, 32, 33 has a shape identical to that of the section of the cylindrical chamber 2 (circular, square, polygonal, etc.) and can thus for example be in the form of a disc, a square or a polygon pierced in its center and arranged coaxially in the chamber 2.

[0094] The first electrode 10 and each second electrode 31, 32, 33 form three pairs of electrodes, each powered by the same generator 40 or by a dedicated generator 40, preferably mounted inside the chamber 2.

[0095] The generator 40 is configured to deliver a voltage between the electrodes of each pair of electrodes so as to cause an electrical discharge between said electrodes in the corresponding filtering space EP1, EP2, EP3, EP4.

[0096] The voltage delivered by the generator 40 is adapted to provide a discharge making it possible to crush the elements of rock material positioned between each first electrode 10 and second electrode 31, 32, 33 of each pair of electrodes. For example, the voltage can be several hundred kilovolts or several gigavolts.

[0097] First type of arrangement (figures 5 to 9): central filtering

[0098] In this type of arrangement, the first electrode 10 is central and is preferably an anode. The first electrode 10 is cylindrical and may be a solid cylinder (Figures 5 to 8) or a hollow cylinder () in which at least one generator 40 is mounted.

[0099] The positioning elements 21, 22, 23, 24 are stacked coaxially around the first cylindrical electrode 10 along the longitudinal axis of said first electrode 10 on a base 2. The diameter of the positioning elements 21, 22, 23, 24 decreases from bottom to top.

[0100] The cross-section of each positioning element 21, 22, 23, 24 has a shape identical to the shape of the cross-section of the first cylindrical electrode 10 while being of larger dimensions so as to be able to place said positioning element 21, 22, 23, 24 around the first electrode 10 while radially forming a filtering space EP1, EP2, EP3, EP4 between said positioning element 21, 22, 23, 24 and the first electrode 10. Each filtering space EP1, EP2, EP3, EP4 thus formed makes it possible to receive rock material of dimensions smaller than its width.

[0101] So, in the example of the:

[0102] - the first positioning element 21 is arranged around the first electrode 10 of the first electrode 10 forming a first filtering space EP1 with the first electrode 10,

[0103] - the second positioning element 22 is arranged above the first positioning element 21 around the first electrode 10, radially forming a second filtering space EP2 with the first electrode 10, the width of said second filtering space EP2 being greater than the width of the first filtering space EP1 and the first support portion PP1 of the first positioning element 21 being configured to support the rock material elements located in said second filtering space EP2,

[0104] - the third positioning element 23 is arranged above the second positioning element 22 around the first electrode 10, radially forming a third filtering space EP3 with the first electrode 10, the width of said third filtering space EP3 being greater than the width of the second filtering space EP2 and the second support portion PP2 of the second positioning element 22 being configured to support the rock material elements located in said third filtering space EP3,

[0105] - the fourth positioning element 24 is arranged above the third positioning element 23 around the first electrode 10, radially forming a fourth filtering space EP4 with the first electrode 10, the width of said fourth filtering space EP4 being greater than the width of the third filtering space EP1 and the third support portion PP3 of the third positioning element 23 being configured to support the rock material elements located in said fourth filtering space EP4.

[0106] A truncated cone-shaped directional element (not shown) may be positioned coaxially above the stack of positioning elements 21, 22, 23, 24 with the smaller diameter downwards flush with the fourth filtering space EP4 in order to guide the pieces of rock introduced into the crusher 1 directly towards the fourth filtering space EP4.

[0107] Figures 6 and 7 show two examples of the shape of the grinder 1 (cross-sectional views). In example 1a, the positioning elements 21, 22, 23, 24, the filter spaces EP1, EP2, EP3, EP4, the first electrode 10 and the second electrodes 31, 32, 33 are circular in shape. In example 1a, the positioning elements 21, 22, 23, 24, the filter spaces EP1, EP2, EP3, EP4, the first electrode 10 and the second electrodes 31, 32, 33 are square in shape.

[0108] In the example of 1a, a generator 40 is housed in one part of the internal space of the chamber 2 and the stack of positioning elements 21, 22, 23, 24 and the second electrodes 31, 32, 33 is housed in the other part.

[0109] Second type of arrangement (figures 10 to 12): peripheral filtering

[0110] In this type of arrangement, the first electrode 10 is peripheral and is preferably a cathode. The first electrode 10 is a hollow cylinder () in which the stack of positioning elements 21, 22, 23, 24 and the second electrodes 31, 32, 33 are mounted.

[0111] The positioning elements 21, 22, 23, 24 are stacked coaxially in the internal space 115 of the first electrode 10 along the longitudinal axis of the first cylindrical electrode 10. The diameter of the positioning elements 21, 22, 23, 24 decreases from bottom to top.

[0112] The edge of each positioning element 21, 22, 23, 24 has a shape identical to the shape of the cross-section of the first cylindrical electrode 10 while being of smaller dimensions so as to be able to place said positioning element 21, 22, 23, 24 in the internal space delimited by the first electrode 10 by radially forming a filtering space EP1, EP2, EP3, EP4 between said positioning element 21, 22, 23, 24 and the first electrode 10. Each filtering space EP1, EP2, EP3, EP4 thus formed makes it possible to receive rock material of smaller diameter or smaller width. The filtering spaces EP1, EP2, EP3, EP4 communicate fluidically with each other to circulate increasingly smaller elements of rock material towards the collector 50.

[0113] So, in the example of the:

[0114] - the first positioning element 21 is arranged in the center of the first electrode 10 so as to radially form a first filtering space EP1 between said first positioning element 21 and the first electrode 10,

[0115] - the second positioning element 22 is arranged above the first positioning element 21 in the center of the first electrode 10 so as to radially form a second filtering space EP2 between said second positioning element 22 and the first electrode 10, the width of said second filtering space EP2 being greater than the width of the first filtering space EP1 and the support portion PP1 of the first positioning element 21 being configured to support the rock material elements located in said second filtering space EP2,

[0116] - the third positioning element 23 is arranged above the second positioning element 22 in the center of the first electrode 10 so as to radially form a third filtering space EP3 between said third positioning element 23 and the first electrode 10, the width of said third filtering space EP3 being greater than the width of the second filtering space EP2 and the support portion PP2 of the second positioning element 22 being configured to support the rock material elements located in said third filtering space EP3,

[0117] - the fourth positioning element 24 is arranged above the third positioning element 23 in the center of the first electrode 10 so as to radially form a fourth filtering space EP4 between said fourth positioning element 24 and the first electrode 10, the width of said fourth filtering space EP4 being greater than the width of the third filtering space EP1 and the third support portion PP3 of the third positioning element 23 being configured to support the rock material elements located in said fourth filtering space EP4.

[0118] A cone-shaped directional element (not shown) may be positioned coaxially above the stack of positioning elements 21, 22, 23, 24 with the tip upwards in order to direct the rocks introduced into the center of the crusher 1 from above directly into the fourth filter space EP4.

[0119] In the example of the, the generator 40 is advantageously housed in the center of the first electrode 10 and the positioning elements 21, 22, 23, 24 in order to optimize the size of the grinder 1.

[0120] In the example of the, several generators 40 are advantageously housed in the center of the first electrode 10 and the positioning elements 21, 22, 23, 24 in a superimposed manner in order to optimize the size of the crusher 1, each generator 40 being connected to the first electrode 10 and to one and only one second electrode 31, 32, 33.

[0121] In the example of 1a, a single generator 40 is housed in one part of the internal space of the chamber 2 and the stack of positioning elements 21, 22, 23, 24 and the second electrodes 31, 32, 33 is housed in the other part.

[0122] Third type of arrangement()

[0123] Another example of an arrangement of the mill 1 according to the invention 1 is shown in which positioning elements 21, 22, 23, 24 are rectangular and positioned two by two facing each other. Each stage comprises a first linear electrode 10-1, 10-2, 10-3 in the form of a rod and a second linear electrode 31, 32, 33 also in the form of a rod, arranged opposite the first electrode 10-1, 10-2, 10-3. The filtering spaces EP1, EP2, EP3, EP4 are formed between the edges of the positioning elements being facing each other.

[0124] Additional equipment

[0125] Advantageously, the crusher 1 can further comprise an electronic controller and presence sensors (not shown) arranged in the filtering spaces EP1, EP, EP3, EP4.

[0126] Each sensor is each configured to detect the presence of rock material in a volume of a filtering space EP1, EP, EP3, EP4 and to send detection signals to the electronic controller. The electronic controller is configured to control the generator 40 so that said generator 40 applies a voltage to the terminals of the first electrode 10 and at least one second electrode in order to trigger an electrical crushing discharge in said volume following the detection of pieces of rock in the space associated with the sensor. The electronic controller comprises a processor capable of implementing a set of instructions making it possible to carry out these functions.

[0127] The crusher 1 can advantageously be configured to automatically control a series of electrical discharges between the first electrode 10 and at least one second electrode, preferably at a frequency of between 1 and 15 Hz.

[0128] Shape of filter spaces

[0129] In the previous examples, the filter spaces EP1, EP2, EP3, EP4 had a straight vertical shape.

[0130] Another example of a configuration of the first filtering space EP1 having an elbow shape is shown on the figure and another example of a configuration of the first filtering space having a shape inclined at 45° is shown on the figure.

[0131] There is shown an advantageous configuration of a positioning element 21 comprising a multitude of filtering spaces EP1 formed in the support portion.

[0132] Implementation example

[0133] An example of implementation will now be described with reference to the.

[0134] As a prerequisite, the crusher 1 is arranged vertically in the use position.

[0135] The rock material is introduced into the crusher 1 in a step E1 so as to allow the rock material elements MT to descend by gravity from top to bottom in a step E2, depending on their size, into the filtering spaces EP4, EP3, EP2, EP1, and at least into the upper filtering space (EP2 in the example of 1 and EP4 in the examples of figures 5 to 13).

[0136] The positioning elements 21, 22, 23, 24 allow the positioning of the rock material MT at least in part in the successive filtering spaces EP4, EP3, EP2, EP1, from the highest located positioning element, up to the first positioning element 21 depending on the space available and the size of the rock material elements MT.

[0137] A portion of the rock material MT is positioned between the first electrode 10 and at least one of the second electrodes 31, 32, 33 in a step E3 by being supported by the support portion PP1, PP2, PP3 of the positioning element 21, 22, 23 located immediately below.

[0138] A flow of liquid F (see for example), preferably water, is advantageously introduced from the top of the crusher 1 continuously in a step E4 to circulate the pieces of rock material from top to bottom through the filtering spaces EP1, EP2, EP3, EP4 throughout the process.

[0139] Once the rock material is positioned at least in one of the filtering spaces EP1, EP2, EP3, EP4, the voltage supplied by the generator 40 is applied in a step E5 between the first electrode 10 and the second electrodes 31, 32, 33 in order to trigger an electric discharge between the electrodes 10, 31, 32, 33 of each pair of electrodes thus formed and then grind the rock material positioned between said electrodes 10, 31, 32, 33.

[0140] In doing so, the material crushed by the electric discharges descends into the lower filter space to be ground again by electric discharge while being further entrained by the descending water flow, until finally reaching the first filter space EP1 below which it can be discharged from the crusher 1 in a step E6 to the collector 50.

[0141] Results

[0142] A prior art mechanical solution for grinding a mass of rock material, containing copper, to a diameter of less than 200 μm requires a very large amount of energy because it is necessary to grind all the material mechanically.

[0143] By using rock material with a diameter of less than 15 mm at the inlet of the crusher 1 (width of the fourth filtering space) and 1.5 mm at the outlet of the crusher 1 (width of the first filtering space), the crusher 1 according to the invention makes it possible to produce a significant quantity of rock dust during successive discharges, of the order of 25% of the total mass at the inlet, which contains more than 70% copper, compared to 25% for previous conventional methods using mechanical crushing and less than 50% for previous conventional methods using electric crushing.

Claims

Crusher (1) for rock material (MT) by electric discharge, said crusher (1) comprising: - a crushing chamber (2) comprising at least one side wall (3) defining an internal space (2A), an upper face (2B) through which the rock material (MT) is introduced and a lower face (2C) through which the crushed rock material (MT) is collected, - at least one first positioning element (21), made of an electrically insulating material, mounted in the internal space at the lower face of the chamber and positioned so as to form a first filtering space (EP1) for discharging crushed rock material (MT) through the lower face of the chamber (2), said at least one first positioning element (21) comprising on its upper surface, along the first filtering space, a support portion (PP1) configured to support rock material (MT), - at least one second positioning element (22),made of an electrically insulating material and having dimensions smaller than the dimensions of a first positioning element (21), each second positioning element (22) having a free edge (31A) and being mounted in the internal space (2A) above a first positioning element (21) so that said free edge (31A) delimits a second filtering space (EP2) extending above the support portion (PP1) of the first positioning element (21) located below and up to the first filtering space (EP1), the free edge (31A) of the second positioning element (22) and the support portion (PP1) of the first positioning element (21) located below thus making it possible to position rock material (MT) in said second filtering space (EP2), - at least one pair of electrodes comprising a first electrode (10) and a second electrode (31), arranged face to face on either side of the second filtering space (EP2),- at least one generator (40) configured to apply a voltage between the first electrode (10) and the at least one second electrode (31, 32, 33) so as to cause an electric discharge to grind the rock material elements (MT) positioned in the second filtering space (EP2) and thus allow at least a portion of the crushed rock material (MT) to pass into the first filtering space (EP1) to be collected., Grinder (1) according to claim 1, said grinder (1) comprising more than two positioning elements (21, 22, 23, 24) each made of an electrically insulating material and stacked one above the other, the dimensions of an upper positioning element being smaller than the dimensions of the immediately lower positioning element so as to form a filtering space of width greater than the width of the at least one filtering space formed by the immediately lower positioning element and opening onto said filtering space formed by the immediately lower positioning element. Grinder (1) according to any one of the preceding claims, said grinder (1) comprising a single first electrode (10) of cylindrical shape. Grinder (1) according to the preceding claim, wherein the positioning elements (21, 22, 23, 24) are mounted inside the first electrode (10) and the filtering spaces are formed against the inner wall of said first electrode (10). Grinder (1) according to claim 3, wherein the positioning elements (21, 22, 23, 24) are mounted around the first electrode (10) and the filter spaces are formed against the outer wall of said first electrode (10). Grinder (1) according to any one of claims 1 or 2, wherein the at least one first electrode (10) and the at least one second electrode (31, 32, 33) are linear in shape. Crusher (1) according to any one of the preceding claims, in which the crusher (1) comprises in its upper part at least one fluid inlet configured to deliver a flow of fluid in order to convey the pieces of rock material (MT) through the successive filtering spaces (EP1, EP2, EP3, EP4) according to their size to crush them and then evacuate them. Grinder (1) according to any one of the preceding claims, wherein the width of the first filtering space (EP1) is less than 5 mm, preferably less than 3 mm, more preferably less than 2 mm. Crusher (1) according to any one of the preceding claims, said crusher (1) further comprising at least one presence sensor configured to detect the presence of rock material (MT) between the electrodes of the at least one pair of electrodes and thus cause the triggering of a crushing shot. A method of crushing rock material (MT) by electrical discharge, said method, implemented by a crusher (1) according to any one of the preceding claims arranged vertically in the position of use, comprising the steps of:- introducing rock material (MT) through the upper face of the chamber (2),- positioning rock material (MT) at least in the filtering space (EP2; EP4) defined by the uppermost positioning element (22; 24) between the electrodes (10; 31, 32, 33) of at least one pair of electrodes, said rock material (MT) being supported by the support portion (PP1, PP2, PP3) of the positioning element (21; 23) located immediately below the positioning element (22;24) the highest,- triggering of at least one electrical discharge at each stage, preferably a succession of discharges, from a voltage supplied by the at least one generator (40) in order to grind the rock material (MT) positioned between said electrodes of each stage,- conveying of the increasingly fine rock material (MT) through the successive filtering spaces (EP4, EP3, EP2, EP1) from top to bottom,- evacuation of the crushed rock material (MT) through the first filtering space (EP1), preferably towards a collector (50) fixed under the lower face of the chamber (2).;

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