Method for operating an open-pit mine

Abstract

Method of operating an open-pit mining site. Method of operating a mining site comprising a layer (3) of a material to be extracted, the method comprising the following operations: - digging a gallery (5) having one end opening to the outside; - arranging a transport conveyor (19) in the gallery, the conveyor extending at least to the end; - digging a shaft (21), opening into the gallery, through the layer (3), the layer (3) of material comprising several superimposed sub-layers (23), each step of extraction of a sub-layer (23) comprising the following operations: - cutting the material from the sub-layer (23); - rolling the material to at least one shaft (21) and dumping it into at least one shaft (21); - Transport of the material using the conveyor (19) along the gallery (5) at least to the end (7). Figure for the abbreviation: Figure 3

Description

Title of the invention: Method for operating an open-pit mining site

[0001] The invention generally relates to the operation of an open-pit mining site, such as an open-pit mine or an open-pit quarry.

[0002] Such a site comprises a layer of a material to be extracted.

[0003] The layer is typically extracted sub-layer by sub-layer, the sub-layers being extracted one after the other starting from the top.

[0004] The exploitation of the site thus leads to the creation of a pit or the leveling of a mountain, as the sub-layers are removed.

[0005] This pit can reach a great depth, since the layer of material to be extracted can have a thickness of more than 150 m.

[0006] The material is typically lifted out of the pit by a series of dump trucks. These dump trucks, once loaded, weigh several dozen tons. The trucks lift the material from the bottom of the pit to a storage and / or material removal station. At this station, the material is temporarily stored, then transferred onto another means of transport: train, conveyor belt, etc.

[0007] Such an exploitation method requires the use of a large number of trucks, and results in the consumption of a large quantity of fuel. Indeed, the trucks are very heavy, and must lift the material to a significant height, the consumption of fossil energy being therefore high.

[0008] In this context, the invention aims to propose an exploitation method which is less greedy in fossil energy while allowing efficient exploitation of the extraction site.

[0009] To this end, the invention relates to a method for operating an open-pit extraction site such as an open-pit mine or an open-pit quarry, the site comprising a layer of a material to be extracted, the method comprising a phase of developing the extraction site, followed by a phase of operating the extraction site, the development phase comprising the following operations: - digging a gallery under said layer, the gallery having one end opening to the outside; - arranging a transport conveyor in the gallery, the transport conveyor extending at least to the end; - digging at least one shaft through the layer, the shaft opening into the gallery;the layer of material to be extracted comprising several sub-layers superimposed on one another, the exploitation phase comprising successive steps of extraction of one of the sub-layers, the sub-layers being extracted one after the other starting from the top; each step of extracting a sub-layer comprising the following operations: - cutting down the material from the sub-layer; - rolling the material to at least one shaft and dumping it into the at least one shaft; - transporting the material using the transport conveyor along the gallery at least to the end. Thus, the materials are evacuated to the evacuation station by a transport conveyor, circulating in a gallery arranged under the layer of material to be extracted. It is therefore no longer necessary to use a stream of trucks to bring the material up out of the pit which is created due to the operation of the extraction site.

[0010] The trucks are at most used for the operation of rolling the material, from the cutting face of the material to the at least one shaft. The at least one shaft crosses all the sub-layers. To go from the cutting face to the shaft, the difference in height to be crossed by the trucks is extremely small.

[0011] Because the journey is short, and the difference in height is reduced, the travel time from the working face to the at least one shaft is short, so that the number of trucks to be used for transferring the material is much lower than in a conventional mining method.

[0012] Overall, the consumption of fossil energy for the transfer of the material to the storage and / or disposal station is reduced in very large proportions.

[0013] The use of a transport conveyor allows the material to be transported at a high rate to the evacuation station. The process of operating the extraction site is therefore extremely efficient.

[0014] The operating method may further have one or more of the following characteristics, considered individually or in all technically possible combinations:

[0015] - a crusher is arranged above the at least one well, the material being crushed before being poured into the at least one well; - several shafts are dug through the layer during the digging operation, each shaft opening into the gallery, the shafts being distributed along the gallery; - the crusher is mobile, and is moved successively over several wells during the extraction stage of a sub-layer; - during the extraction stage of a given sub-layer, the crusher is moved into a trench made in the sub-layer immediately below; - during the extraction step of a given sub-layer the crusher remains at the same level, the crusher having descended to a lower level at the end of the extraction step of said given sub-layer; - the rolling operation is carried out by trucks, the trucks remaining sen possibly at the same level during the extraction step of a given sub-layer; - - a transfer conveyor is arranged under a lower end of the or each well, the transfer conveyor being arranged to transfer the material onto the transport conveyor; - a hopper is arranged between the lower end of the shaft and the transfer conveyor; and - the transport conveyor is a belt conveyor.

[0016] Other characteristics and advantages of the invention will emerge from the detailed description given below, for information purposes only and in no way limiting, with reference to the appended figures, among which:

[0017] [Fig-1] [Fig.l] is a top view of an opencast mining site;

[0018] [Fig.2] [Fig.2] is a longitudinal sectional view of the operating site of the [Fig.l], showing the gallery dug under the layer to be extracted and various shafts opening into the gallery;

[0019] [Fig.3] [Fig.3] is an enlarged view of a shaft, showing a crusher positioned above- above the well;

[0020] [Fig.4] [Fig.4] is an enlarged view of the crusher; and

[0021] [Fig.5] [Fig.5] is an enlarged view of the transfer conveyor placed below the well of [Fig.3], allowing the crushed material to be transferred onto the transport conveyor running through the gallery.

[0022] The method which will now be described is a method of operating an opencast mining site of the type shown schematically in [Fig.l].

[0023] This extraction site 1 is an open-pit mine or an open-pit quarry.

[0024] The site comprises a layer of a material to be extracted 3. This layer 3 has ty stinging a significant length, width and depth.

[0025] For example, layer 3 has a longitudinal length of several kilometers, a transverse width of several kilometers, and a depth of several tens or even several hundreds of meters.

[0026] The longitudinal direction here corresponds to the direction in which layer 3 has its largest dimension. The transverse direction is the direction perpendicular to the longitudinal direction.

[0027] For example, layer 3 has a length of 8 kilometers, a width of 2 kilometers and a depth of 170 meters.

[0028] The mass of material to be extracted is several million tons, for example 90 million tonnes.

[0029] The material to be extracted is of any type: ore containing a metal such as iron, aluminum or nickel, coal, etc.

[0030] The method first comprises a phase of development of the extraction site 1, followed by a phase of exploitation of the extraction site 1.

[0031] The development phase includes an operation of digging a gallery 5 under layer 3.

[0032] Gallery 5 is an underground gallery.

[0033] Advantageously, the gallery 5 is arranged so as to run through the layer 3 over its greatest length, that is to say longitudinally.

[0034] It extends over the entire longitudinal length of layer 3.

[0035] Gallery 5 has an end 7 opening to the outside at a distance from layer 3.

[0036] End 7 opens onto the surface.

[0037] It is typically located near a material storage and / or removal station 9, as illustrated in [Fig.2].

[0038] Thus, gallery 5 comprises a main section 11 located at the right of layer 3, that is to say vertically under layer 3.

[0039] This main section is typically substantially horizontal. It is located at a shallow depth below layer 3.

[0040] The gallery 5 also includes an inclined section 13 connecting the main section 11 to the end 7. The inclined section 13 rises from the level of the main section 11 to the ground level, at which the end 7 is located.

[0041] Opposite the end 7, the gallery 11 is closed, or, as illustrated in [Fig.2], has another end 15 opening outwards. The other end 15 opens out at ground level, longitudinally on the other side of the layer 3 relative to the end 7. The other end 15 is connected to the main section 11 by another inclined section 17.

[0042] Station 9 is provided for temporary storage and / or removal of material.

[0043] At station 9, the material is for example stored in piles, or in blocks, as illustrated in [Fig.2]. At station 9, the material is loaded into a means of transport (not shown) allowing this material to be removed far from the site, to a point of final use.

[0044] This means of transport is of any type suitable: train, conveyor belt, truck, etc.

[0045] Alternatively, the station 9 comprises means for transforming the material 9, for example for extracting a component of interest from the evacuated material.

[0046] The fitting-out phase also includes an operation of fitting out a transport conveyor 19 in gallery 5.

[0047] The conveyor is visible in Figures 3 and 5.

[0048] The transport conveyor 19 extends at least to the end 7 of the gallery 5.

[0049] Typically, it extends to the material storage and / or evacuation station 9.

[0050] It extends over at least part of the length of gallery 5.

[0051] Typically, it extends along the entire length of gallery 5.

[0052] The transport conveyor 19 is of any suitable type. Typically, it is a belt conveyor.

[0053] The development phase also includes the digging of at least one shaft 21 through layer 3. The at least one shaft 21 opens into gallery 5.

[0054] The at least one well 21 passes through the entire thickness of the layer 3, from the upper surface 8 of the layer 3 to the gallery 5.

[0055] Typically, the at least one well 21 is vertical.

[0056] Its upper end is open at the level of the upper surface 8 of the ground. Its lower end communicates with the gallery 5.

[0057] Preferably, several wells 21 are dug through the layer 3 during the digging operation, each well 21 opening into the gallery 5.

[0058] The wells 21 are distributed along the gallery 5. Preferably, the wells 21 are regularly distributed along the gallery 5. In [Fig.2], certain wells are not shown.

[0059] The transport conveyor 19 is preferably arranged so as to pass at the level of each well 21.

[0060] The layer 3 of material to be extracted comprises several sub-layers 23, superimposed on top of each other.

[0061] The exploitation phase comprises successive steps of extracting one of the sub-layers 23, the sub-layers 23 being extracted one after the other starting from the top.

[0062] In other words, the site is exploited sub-layer by sub-layer, the material from one sub-layer being extracted before starting to extract the sub-layer immediately below.

[0063] Each sub-layer 23 has a height typically between 5 and 15 meters. It can also be designated by the term “step”.

[0064] The sub-layers 23 are not physically distinct from each other. Each sub-layer simply corresponds to the thickness of material removed during a stage of operation of the site.

[0065] Typically, during an extraction step, only one area of ​​the sub-layer 23 is extracted. In the next extraction step, the area of ​​the lower sub-layer located exactly below the area of ​​the upper layer already extracted is extracted. In other words, the site is exploited area by area, which makes it possible to reach the depths where products of interest are found more quickly.

[0066] Alternatively, the entire sub-layer 23 is removed before attacking the in- sub-layer lower.

[0067] Each step of extracting a sub-layer 23 comprises the following operations:

[0068] - cutting down the material of the sub-layer 23;

[0069] - rolling the material cut to the at least one well 21 and dumping into the at least one well 21 minus one well 21;

[0070] - transport of the material using the transport conveyor 19 along the gallery 5 to the outside, typically to the material storage and / or disposal station.

[0071] The felling operation is carried out by any suitable means: explosives, mechanical shovels 25, scrapers, etc. ([Fig.3]).

[0072] The sub-layer is removed, for example, from one longitudinal end of the area to be extracted, progressing longitudinally towards the other end.

[0073] The cutting face 26 thus moves substantially longitudinally from one end of the sub-layer to the other.

[0074] The material rolling operation is carried out by large capacity dump trucks 27, as shown in [Fig.3].

[0075] The trucks 27 are used to transport the material from the working face 26 to the at least one shaft 21. At the working face 26, they are loaded for example by the shovels 25 or by loaders not shown.

[0076] They transport the material to the shaft 21 closest to the working face 26.

[0077] Advantageously, and as illustrated in Figures 3 and 4, a crusher 29 is arranged above the well 21, the material being crushed before being poured into the well.

[0078] The crusher 29 is of any suitable type. The crusher 29 is for example a primary gyratory crusher.

[0079] The crusher 29 crushes the material brought by the trucks 27 and transforms it into blocks of sizes suitable for being transported on the transport conveyor 19.

[0080] As visible in Figures 3 and 5, a transfer conveyor 31 is arranged under a lower end of the or each well 21.

[0081] The transfer conveyor 31 is arranged to transfer the material onto the transport conveyor 19.

[0082] The transfer conveyor 31 is for example a plate conveyor.

[0083] The plates 33 are metallic, and are hinged to each other so as to form a continuous track. This track is closed in a loop and is mounted around two turning drums 35, located at the two ends of the transfer conveyor.

[0084] The track thus comprises an upper strand 37 receiving the material arriving from the well 21, supported by a large number of support rollers 39. It also comprises a lower return strand, circulating under the upper strand.

[0085] A hopper 41 is arranged between the lower end of the well 21 and the transfer conveyor 31. The hopper 41 directs the material exiting the well 21 onto the transfer conveyor 31.

[0086] A downstream end of the transfer conveyor 31 is located immediately above the transport conveyor 19. A further hopper 43 is placed below said downstream end. It is arranged to receive the material coming from the transfer conveyor 31, and to guide it so that it falls onto the transport conveyor 19.

[0087] It should be noted that a deck 45 is placed around the upper strand 37 and around the downstream end of the transfer conveyor. This deck 45 rises to the lower orifice of the hopper 41. The deck 45 makes it possible to hold the material arriving via the hopper 41 on the upper strand 37 of the transfer conveyor, and, at the downstream end of the transfer conveyor, guides the material to the hopper 43.

[0088] The transfer conveyor 31 is mounted on a rigid frame 47, capable of taking up a significant weight.

[0089] Similarly, the transfer conveyor 31 is also capable of supporting a significant mass of material.

[0090] As explained below, in operation, the well 21 is practically filled over its entire height with the crushed material from the crusher 29. At least a fraction of the weight of the column of material filling the well 21 is supported by the transfer conveyor 31, this weight being taken up by the chassis 47. The chassis 47 and the transfer conveyor 31 are sized to support this weight.

[0091] As can be seen in particular in [Fig.4], the crusher 29 is mobile, and is moved successively above each well 21 of the zone to be extracted during the step of extracting a sub-layer.

[0092] The crusher 29 is mounted on tracks 48, so as to be able to move from one well 21 to another.

[0093] As visible in Figures 3 and 4, during the step of extracting a sub-layer, the crusher 29 moves in a trench 49 which is formed in the sub-layer 23 immediately below.

[0094] Trench 49 is substantially parallel to gallery 5.

[0095] It passes through all the wells 21 of the area to be extracted. It extends over a fraction of the length of gallery 5, and is located vertically to the right of it.

[0096] The trench 49 is partially covered by a floor 51, supported by stacks of blocks 53, typically made of concrete. An opening 55 is provided in the floor 51, at the level of the hopper 57 for feeding the crusher 29.

[0097] The dump trucks 27 unload their load through the opening 55, to feed the crusher 29.

[0098] Thus, during the exploitation phase, each sub-layer 23 is successively excavated, starting with the upper sub-layer.

[0099] Typically, for a given sub-layer, the working face 26 moves longitudinally from one end of the zone to be extracted from the sub-layer 23 towards the other end. Once the working face 26 has passed the first shaft 21, located closest to the starting end, a first section of the trench 49 is created in the lower sub-layer 23, and the crusher 29 is placed above the first shaft 21.

[0100] The materials extracted at the working face 26 are loaded into the trucks 27, which transport them to the first shaft 21. For this, they circulate on the upper surface of the lower sub-layer.

[0101] They pour the material into the opening 55.

[0102] The hopper 57 guides the material discharged into the crusher 29.

[0103] The material is crushed in the crusher 29, and reduced to blocks which fall into the well 21.

[0104] The well 21, as illustrated in [Fig. 3], is constantly filled with a column of crushed material. Thus, the height of fall of the crushed material is relatively limited, so that the shocks suffered by the transfer conveyor 31 at the bottom of the well 21 are very reduced.

[0105] At the bottom of the shaft 21, the crushed material exiting the shaft is directed by the hopper 41 onto the transfer conveyor 31. The upper strand 37 moves the crushed material to the downstream end of the transfer conveyor.

[0106] During its movement, the crushed material is guided by the deck 45.

[0107] At the downstream end, it falls into the hopper 43, which guides the crushed material so that it falls onto the transport conveyor 19.

[0108] The transport conveyor 19 transports the material along the gallery 5, to the outside of the gallery, typically to the storage and / or evacuation station 9.

[0109] The flow rate of material supplied by the trucks 27 is substantially equal to the flow rate of the crusher 29.

[0110] Similarly, the flow rate of the transfer conveyor 31 is adjusted to be equal to the flow rate of the crusher 29. The transport conveyor 19 is adjusted to discharge the material at a flow rate equal to that coming from the transfer conveyor 31.

[0111] This prevents the material from accumulating at the level of the crusher 29, in the well 21, at the level of the transfer conveyor 31 or at the level of the transport conveyor 19.

[0112] Once the working face 26 has passed the second shaft 21, the trench 49 is extended, and the crusher 29 is moved to the second shaft 21.

[0113] The trucks 27 then ensure the transport of the material from the working face 26 to the second shaft, so as to limit the amplitude of the transport of the materials.

[0114] The working face 26 moves progressively to the other end of the zone, all the shafts 21 located in the zone being used in turn to evacuate the material to gallery 5.

[0115] Trench 49 is extended from well to well, as the working face 26 moves.

[0116] Once the exploitation of a given sub-layer 23 is completed, or practically completed, the exploitation of the immediately lower sub-layer 23 begins. The crusher 29 is then moved to the lower level.

[0117] Thus, during the step of extracting a given sub-layer 23, the crusher 29 is moved exclusively in the same level, which corresponds in the example shown to the level of the immediately lower sub-layer 23. The crusher 29 is lowered to the lower level at the end of the step of extracting said given sub-layer.

[0118] Similarly, during the step of extracting a given sub-layer, the rolling operation is carried out by the trucks 27, these trucks remaining substantially at the same level throughout the step of extracting the sub-layer 23.

[0119] The method described above has multiple advantages.

[0120] Using a crusher placed above the shaft allows the material to be reduced into blocks that can be easily transported by the transport conveyor 19. This contributes to the efficiency of the transport of the material.

[0121] By digging several shafts, distributed along gallery 5, it is always possible to use a shaft located close to the working face for the evacuation of the material. The distance to be covered by trucks transporting the material from the working face to the shaft is thus shortened, and the quantity of gasoline used is reduced.

[0122] Using a mobile shredder is economical, as the same shredder is used at all stages of site operation. Equipment investment is reduced.

[0123] Moving the crusher into a trench in the sub-layer immediately below the mined sub-layer makes it easy to dump the material into the crusher. This contributes to the efficiency of the mining process.

[0124] The fact that the crusher remains at the same level throughout the extraction stage of a given sub-layer makes it possible to reduce the number of movements and the complexity of moving the crusher, which contributes to the efficiency of the operating process.

[0125] The fact that the trucks, during the extraction stage of a given sub-layer, remain substantially at the same level contributes to reducing the fuel consumption of these trucks.

[0126] The use of a transfer conveyor arranged under the lower end of Each well for transferring the material onto the transport conveyor allows this transfer to be carried out efficiently and economically.

[0127] Using a belt conveyor allows the material to be transported along the gallery efficiently and economically, with low energy consumption.

[0128] The extraction process can have multiple variants.

[0129] It is possible to dig several galleries under the layer. These galleries are then parallel, or on the contrary non-parallel. A transport conveyor is arranged in each gallery. Alternatively, a single transport conveyor is used, this being dismantled and reassembled from one gallery to another.

[0130] The development phase may involve the digging of a single well, or on the contrary several wells.

[0131] The step of extracting a given sub-layer may not be completed when the extraction of the immediately lower sub-layer starts. For example, the step of extracting the immediately lower sub-layer may start when the step of extracting the sub-layer is only 50% complete.

[0132] In this case, several wells are advantageously in service at the same time, one well for the upper sub-layer and another for the lower sub-layer.

[0133] Several grinders are used simultaneously.

[0134] Rolling the material to the well can be done by any suitable vehicle or machine, not necessarily by the trucks shown in the figures.

Claims

Claims

1. A method of operating an open-pit mining site such as an open-pit mine or an open-pit quarry, the site (1) comprising a layer (3) of a material to be extracted, the method comprising a phase of developing the mining site (1), followed by a phase of operating the mining site (1), the development phase comprising the following operations: - digging a gallery (5) under said layer (3), the gallery (5) having one end (7) opening to the outside; - arranging a transport conveyor (19) in the gallery (5), the transport conveyor (19) extending at least to the end (7); - digging at least one shaft (21) through the layer (3), the shaft (21) opening into the gallery (5);the layer (3) of material to be extracted comprising several sub-layers (23) superimposed on one another, the exploitation phase comprising successive steps of extracting one of the sub-layers (23), the sub-layers (23) being extracted one after the other starting from the top, each step of extracting a sub-layer (23) comprising the following operations: - cutting down the material of the sub-layer (23); - rolling the material to the at least one shaft (21) and dumping it into the at least one shaft (21); - transporting the material using the transport conveyor (19) along the gallery (5) at least to the end (7). a crusher (29) is arranged above the at least one shaft (21), the material being crushed before dumping it into the at least one shaft (21).;

2. An operating method according to claim 1, wherein several wells (21) are dug through the layer (3) during the digging operation, each well (21) opening into the gallery (5), the wells (21) being distributed along the gallery (5).

3. An operating method according to claim 2, wherein the crusher (29) is mobile, and is moved successively above several wells (21) during the step of extracting a sub-layer (23).

4. An operating method according to claim 3, wherein during the step of extracting a given sub-layer (23), the crusher (29) is moved into a trench (49) provided in the imme- immediately lower.

5. An operating method according to claim 3 or 4, wherein during the step of extracting a given sub-layer (23) the crusher (29) remains at the same level, the crusher (29) being lowered to a lower level at the end of the step of extracting said given sub-layer (23).

6. An operating method according to any one of the preceding claims, wherein the rolling operation is carried out by trucks (27), the trucks (27) remaining substantially at the same level during the step of extracting a given sub-layer (27).

7. An operating method according to any preceding claim, wherein a transfer conveyor (31) is arranged beneath a lower end of the or each well (21), the transfer conveyor (31) being arranged to transfer the material onto the transport conveyor (19).

8. An operating method according to claim 7, wherein a hopper (41) is arranged between the lower end of the well (21) and the transfer conveyor (31).

9. A method of operation according to any preceding claim, wherein the transport conveyor (19) is a belt conveyor.

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