Patent Application
20230203946
The present invention relates to a cave mining method for mining deposits and the use thereof. The present invention also relates to a cave mining infrastructure, a machinery, a control system of a cave mining infrastructure, and a data medium.
Cave mining methods are applied for underground extraction of mineral deposits. Prior art cave mining methods (also referred to as caving methods) include block caving, panel caving, sublevel caving, inclined caving and variations of these methods. The concept of cave mining relies on that during the mining operation a part of the rock mass caves such as the ore body itself, the rock formations near the ore body, the overlying hangingwall, or a combination thereof. Caving is an engineered, natural failure process of rock mass. Particularly, cave mining methods are associated with low extraction cost. Therefore, cave mining methods are suitable for mining low-grade mineral deposits, which are massive and have a large volumetric extent.
In prior art cave mining methods relying on caving of the ore body, the following main method steps can be distinguished: undercutting, production, and pre-conditioning. In caving methods where the ore body is engineered to cave, such as block caving, inclined caving, or panel caving, caving of the ore body is typically achieved by undercutting the ore body. When undercutting, a void is created by drilling and blasting such that the void obtains a dimension, which is large enough to initiate caving.
After the ore body has been undercut and caving has been initiated, broken ore is drawn through drawbells accessed through drawpoints located at a single production level. As ore is drawn, a void is formed and maintained above the broken, caved rock mass and caving can progress upwards subsequently, whereby a caving stope is formed. The void has to be large enough to absorb the swell of caved rock.
If the ore body rock mass is too strong for enabling cave progression under prevailing stress conditions at an acceptable caving rate, or if no caving occurs at all or pre-conditioning methods may be implemented to decrease rock mass strength.
Each of the main method steps undercutting, production and pre-conditioning require typically different types of infrastructure and work processes.
Undercutting is commonly conducted from undercut drifts on a so-called undercut level where the undercut is created by means of drilling and blasting of pillars between neighboring undercut drifts on retreat. The production is normally conducted from production level drifts on a so-called production level. Drifts, drawpoints, and drawbells have to be developed by means of drilling and blasting, whereby drawpoints and drawbells connect the production level to the undercut area. Furthermore, pre-conditioning measures are typically applied from drifts at so-called pre-conditioning levels by for example hydraulic fracturing and/or confined blasting.
The requirements on the infrastructure and work processes are different for each of the main method steps. Thus, in prior art caving methods the main method steps undercutting, production, and pre-conditioning must be implemented in a stepwise and subsequent manner.
Furthermore, in prior art cave mining methods such as block caving, the undercut and production levels must be proximal due to ore flow considerations. The spacing between drawpoints is dependent on the actual spacing of production and undercut level. The drawpoint spacing must not exceed certain distances to realize an acceptable ore flow in caving stopes. Therefore prior art caving methods such as block caving require numerous, small drawbells to implement an appropriate drawpoint spacing, implying that at the production level there are numerous, small drawbells and drawpoints which are separated by small pillars. Moreover, drawbell development is intense and difficult but it is crucial for ore flow and operational performance. However, the small size of drawbells hinders proper stimulation of the ore flow and limits access. Frequent hang-up occurrences resulting from the small drawbell sizes negatively affect production, productivity, and ore flow. Hang-up clearance is difficult. Furthermore, the spacing varies between the drawpoints, and draw zones are not evenly distributed. Thereby, a non-uniform ore flow may result causing early dilution, poor ore recovery, and even rock mechanical problems at the production level. The close distance between the production level and undercut level also causes major rock mechanical problems. Significant stress changes in the rock mass from undercutting result in extreme stresses at the boundaries of the undercut area, referred to as abutment areas.
In block caving the undercut level and the production level are situated in and affected by the abutment area. Infrastructure at the undercut level and/or the production level may be damaged because of the high stresses necessitating repair before production. Undercut drilling and blasting is complicated and hazardous as the undercut is in the abutment zone, prone to high stresses. At the production level, the small pillars separating drawpoints and drawbells are prone to stress damage. This rock mass damage is immanent and may cause ongoing, long-term, persistent stability problems during lifetime of the operation.
Furthermore, the ramp-up time of prior art cave mining methods is very long and may exceed 10-15 years with considerably high associated cost. Rock mechanics and logistics issues hinder faster ramp-up time. Additionally, financial returns are only generated after production has commenced. Furthermore, design decisions need to usually be locked in an early stage, when access to actual information related to deposit shape, rock mass properties etc. is still very limited. This circumstance may result in incorrect decisions bearing considerable risks during the later run of operation.
Moreover, there is limited or no access to the ore body above the undercut. Thus, the possibility to control the direction of cave progression is very limited. Furthermore, active control through specific and/or on demand rock breaking methods is very difficult and costly to implement in prior art cave mining methods. Hence, prior art cave mining methods require extensive monitoring programs to follow the cave progress. In case of cave stall or unwanted cave progression direction, access points are not readily available for instant remedies.
However, the application of cave mining methods remains attractive, mainly due to the provided high productivity in combination with low extraction costs. Thus, there is a current trend to apply cave mining methods to deeper and more competent ore bodies and to ore bodies with less favorable geometries for caving. These conditions intensify the above-mentioned rock mechanics and logistics issues.
In conclusion, prior art cave mining methods are associated with long development times, complex preparation plans, complex schedules, high development cost, very little flexibility, very little possibilities for adaptations, and high risks. In addition, thereto, the trend to mine deeper, more competent, and lower grade ore bodies aggravates the risks significantly.
In view of prior art cave mining methods it is desirable to achieve a cave mining method for mining ore from a deposit in rock mass which solves or at least alleviates some of the drawbacks of the prior art.
There is one object to provide a cave mining method for mining deposits which improves the safety when cave mining.
There is one object to provide a cave mining method for mining deposits which reduces the risks associated with cave mining.
There is one object to provide a cave mining method which reduces the ramp-up time for developing a cave mine.
There is one object to provide a cave mining method which reduces costs for developing the cave mine.
There is one object to provide a cave mining method which reduces the requirement for pre-development of infrastructure prior to production.
There is one object to provide a cave mining method which increases the profitability and enhances the applicability of cave mining.
There is one object to provide a cave mining method which provides improved stability of the infrastructure.
There is one object to provide a cave mining method which improves interactive draw over larger areas.
There is one object to provide a cave mining method which provides reduced risk of early dilution.
There is one object to provide a cave mining method which provides reduced probability of hang-ups.
There is one object to provide a cave mining method which reduces the infrastructure amount for undercutting.
There is one object to provide a cave mining method which provides that drilling and blasting work for drawbell development and undercutting can be remote controlled or automated.
These or at least one of said objects are achieved by an integrated raise caving mining method as claimed in claim 1, wherein further embodiments are incorporated in the dependent claims.
Hence, according to one aspect the present invention relates to an integrated raise caving mining method for mining deposits in rock mass comprising:
The integrated raise caving mining method advantageously combines and therefore integrates the method steps drawbell development, undercutting, initiating of caving, caving and optionally pre-conditioning and optionally pre-breaking in that all these method steps may be implemented from the same raise in parallel or within a short time frame.
The integrated raise cavinge mining method comprises that the at least one raise is developed in rock mass. A raise refers to a longitudinally extended vertical or inclined mine infrastructure opening. The raise is typically configured with a circular cross-section. The at least one raise may for example be developed from a tunnel, drift, level or other accessible infrastructure in the rock mass. The raise may for example be developed between two levels arranged on different elevations in the rock mass. The at least one raise may be developed in upwards direction by for example raise boring techniques, or alternatively the at least one raise may be developed in downwards or upwards direction by other conventional methods.
Preferably, the raise is developed within an area in the rock mass where the drawbell is intended to be developed.
The orientation and/ or position of the raise may be adapted to local requirements in terms of ore body geometry and/ or stress situation and/ or rock mass properties.
In one embodiment of the invention, the method comprises that the raise is vertical. Alternatively, the raise may be inclined.
In one embodiment of the invention, the method comprises that the at least one raise is developed to extend over the full stope height. In such case the raise may be developed to extend from the bottom of the drawbell to a level located at the top of the stope.
In one embodiment of the invention, the method comprises that the at least one raise is developed to extend over only a part of the stope height above the drawbell. In such case the at least one raise is developed to extend from the bottom of the drawbell to an additional level arranged between the drawbell and the ultimate top of the stope. However, the raise may also be developed between two levels, which are located above the drawbell, thereby the drawbell extends only over a part of the stope height.
In one embodiment of the invention, the method comprises that the at least one raise is located in rock mass within the perimeter of the drawbell roof.
The at least one raise may be located in the center of the drawbell roof. Alternatively the at least one raise may be located offset from the center of the drawbell roof. Thus, the raise is positioned outside the center of the drawbell roof. In one embodiment of the invention, the method comprises that the at least one raise is located in rock mass outside the perimeter of the drawbell roof. In one embodiment of the invention, the method comprises that the drawbell is excavated at least partially from a raise which is located in rock mass outside the perimeter of the drawbell roof. In one embodiment of the invention, the method comprises that the drawbell is excavated from more than one raise. Several raises may be developed in the rock mass within the region where the drawbell is intended to be constructed such that the drawbell is constructed by excavation from several raises.
Evidently, the integrated raise caving mining method may comprise that multiple drawbells are excavated in a mining area.
The integrated raise cavinge mining method comprises that a drawbell is developed in the rock mass. The drawbell is configured to receive fragmented rock material from a caving stope located above the drawbell. The drawbell comprises a drawbell bottom and a drawbell roof, which are joined by sidewalls. Preferably, the drawbell is configured with a drawbell roof area being larger than a bottom area of the drawbell. In such case the drawbell widens in a direction upwards. The area of the horizontal cross-section of the drawbell may vary in upwards direction. Typically the area of the horizontal cross-section of the drawbell gradually increases in upwards direction. The drawbell may for example be configured as an inverted pyramid, a trough or an inverted cone. Alternatively, the area of the horizontal cross-section may be constant, or nearly constant along a section of the drawbell. The drawbell may for example be configured as an inverted cone further provided with a cylindrical section adjacent the drawbell roof.
The integrated raise cavinge mining method comprises that at least a portion of the drawbell is excavated from the at least one raise. For example the lowermost portion of the drawbell may first be excavated by drilling, charging and blasting operations conducted by conventional means from the production level or a drift located in the rock mass. Thereafter the remaining portion of the drawbell is developed by excavation from the at least one raise from inside the raise. Alternatively the complete drawbell is developed by excavation from the at least one raise.
In one embodiment of the invention, the portion of the drawbell is excavated by drilling blast holes into the rock mass around the raise by operating a machinery arranged inside the raise, and blasting the rock mass by charging and detonating explosives in those blast holes such that the portion of the drawbell is blasted.
The drawbell development from the at least one raise provides an advantageous synergizing potential. However, in order to benefit from this potential the drawbell must exceed a certain critical size. The drawbell must be of a sufficient size in order minimize the number of raises. In such way the economy of the mining operation is acceptable from a cost perspective.
The combined application of using at least one raise for drawbell development and the provision of a drawbell of considerable size drastically reduces the ramp-up time of a cave mining operation, allowing using and sharing of the same infrastructure and similar work processes enabling parallel implementation of the method steps drawbell development, undercutting, initiating of caving, and, optionally, pre-conditioning and pre-breaking in the stope.
Accordingly, the drawbell is developed to obtain a considerable size which exceeds a critical size, otherwise the advantages regarding ramp-up time, parallelization, and synergizing effects do not materialize.
The development of the drawbell from the raise allows establishing a much larger drawbell. Moreover, the drawbell can be utilized for undercutting as well. This is a major advantage over prior art cave mining methods where the undercut level usually is located close to the production level and the production level layout is configured with numerous small drawbells to implement an appropriate drawpoint spacing, necessary to achieve an acceptable ore flow in a caving stope of prior art cave mining methods. Thus, the small sized drawbells of prior art production level layouts would not provide the same advantage.
For the purpose of constructing the drawbell by excavation, suitable machinery is arranged inside the raise. Moreover, said machinery may also be used for stope excavation, such as for example pre-breaking.
The machinery comprises a drilling and/or charging machinery configured for drilling and/or charging the rock mass from inside the raise, which machinery comprises a drilling bore and/or charging equipment configured for initiating said caving. The machinery may also comprise hydraulic fracturing equipment. The machinery is arranged on a platform which is movable within the raise such that it can be hoisted down through the raise to a location of operation.
Preferably the machinery is configured to be operated by remote control. Alternatively, the machinery is configured for semiautomation or full automation. Thereby it is avoided that machine operators have to be present inside the raise. Since the raise is preferably configured with a circular cross-section remote control or automation of the machinery is facilitated
The platform must be designed such that it can still be moved inside the raise, even in the case of rock mass deformations occurring in the raise.
The shaft hoist system is located in a specifically excavated infrastructure excavation, which size and shape is adapted to the requirements of the hoist system and/ or rock mechanics considerations. In order to keep the infrastructure excavation of the hoist system 104 small, a modular design of the platform and/ or machinery mounted on the platform is advantageous. A small infrastructure excavation provides an improved stability. The modular design allows changing of utilized machinery quickly.
The machinery mounted onto the platform is adapted to operational requirements. Possible types of machinery comprise amongst others machinery for drilling, machinery for charging, machinery for support installation or machinery for hydraulic fracturing.
In one form of the invention, the platform may also be stored by moving it aside from the top of the raise. Thus the platform is configured to be moved to the side at the top of the raise to be stored in a storage position.
The blast initiation can be carried out with different options, which comprise amongst others non-electric detonators, detonators initiated through an electric signal transferred via cable or detonators initiated wirelessly by means of communication through rock mass.
In another form of the invention, more than one slice could be blasted in a single blast. Thereby an appropriate time delay between individual slices is required.
In one embodiment of the invention, the mining method comprises that excavation of the portion of the drawbell is performed by blasting slices of rock mass. The shape of the slices depends on the inclination of the boreholes. Preferably, the portion of the drawbell is excavated by drilling blast holes into the rock mass around the raise by operating the machinery arranged inside the raise, and blasting the rock mass by charging and detonating explosive charges in those blast holes such that slices of rock mass are blasted.
The excavation and development of the drawbell commences at the bottom of the drawbell. Preferably, the blasting progresses in upwards direction by drilling and blasting slices of rock mass with the machinery arranged inside the raise.
Typically, blast holes are drilled to be straight by conventional techniques, which provide a limited control of drill precision and accordingly limit the maximum possible blast hole length. However, it may be advantageous to apply directional drilling. Directional drilling may be applied for better control of drill precision and/or to accomplish very large drill- and blast design by drilling curved boreholes.
In one embodiment of the invention, the method comprises that blasting takes place in an unconfined environment by drawing previously blasted rock from the drawbell to create a void.
Blasting of the drawbell takes place in an unconfined environment by gradually drawing rock mass from the drawbell thereby creating a void. Sufficient voids must exist to absorb the swell of fragmented rock resulting from blasting. Before the next blast holes can be fired, enough broken rock mass must be drawn from the drawbell. Due to unconfined blasting, rock breakage problems leading to remnant pillars are not expected. However, in case a remnant pillar is formed, it can be detected and measures against the remnant pillar may be implemented. Moreover, the availability of the raise improves the access and facilitates the applicability of measures against remnant pillars. Furthermore, the blasted rock is thrown predominately in the direction of gravity, assisting the blasting process further.
Drilling, charging and blasting continues upwards along the raise. In one embodiment of the invention, the method comprises that excavation of the portion of the drawbell is performed by blasting slices of rock mass. In one embodiment of the invention, the method comprises that the shape of individual blast slices are adapted to form a drawbell of a specific predetermined shape.ln one embodiment of the invention, the method comprises that the drawbell is configured as an inverted pyramid. Alternatively, the drawbell may be configured as an inverted cone or a trough.
In one embodiment of the invention, the method comprises that the shape of the at least one drawbell is configured to be adaptable according to the ore body geometry and/ or rock mass properties and/ or ore flow considerations and/ or stress situation.
In one embodiment of the invention, the method comprises that the dimension of the at least one drawbell is adapted to local requirements in terms of ore body geometry and/ or stress situation and/ or rock mass properties and/ or ore flow considerations.
In one embodiment of the invention, the method comprises that the drawbell is configured to be oriented in a predetermined direction.
In one embodiment of the invention, the method comprises that the drawbell is configured to be oriented such that the production level infrastructure is positioned favorably related to the prevailing stresses.
In one embodiment of the invention, the method comprises that the drawbell is configured to be oriented such that cave initiation is facilitated by the prevailing stresses.
A free surface for blasting is obtained and/ or maintained which coincides with the drawbell roof and provides a favorable condition for later cave initiation. Basically, blasting transforms into caving of the rock mass when the drawbell is excavated in upwards direction.
The integrated raise cavinge mining method comprises thatcaving is initiated through undercutting wherein at least a part of an undercut is created by gradually expanding the drawbell in upwards direction by excavation.
In such a way the area of the drawbell roof is increased, such that at least a part of the undercut is created by the drawbell. This is particularly advantageous in that a separate undercut level, which would otherwise have to be developed, is not required.Thus by gradually expanding the drawbell in upwards direction the drawbell roof becomes larger than the bottom of the drawbell. However, the drawbell may also be gradually expanded in the upwards direction without increasing the length of the perimeter of the drawbell roof. In such a way, a section of the drawbell may be provided with a horizontal cross-section having constant or nearly constant area in upwards direction.
In one embodiment of the invention, the method comprises that at least a part of the undercut is created by gradually expanding the drawbell in the upwards direction without increasing the length perimeter of the drawbell roof.
Alternatively, at least a part of the undercut is created by gradually expanding the drawbell upwards in vertical direction by excavation.
Preferably the rock mass located above the drawbell caves, thereby forming a stope. Caving is initiated subsequently to creating the undercut. Thereby, caving is initiated when the area of the undercut exceeds a critical area, which is a function of rock mass properties, stress situation, and the shape of the undercut. The critical area for caving of different types of rock mass and different location is well researched in the field, and may be estimated by the skilled person.
In one embodiment of the invention, the method comprises performing drawbell development and undercutting simultaneously. The gradual expansion of the drawbell, whereby the drawbell roof area is gradually increased, is part of the undercutting process. In such a way, the ramp-up time can be shortened in comparison with prior art methods. Also, the drawbell serves as an initial source of ore due to its size. Therefore, some ore can already be produced in the ramp-up stage of the operation.
In one embodiment of the invention, the method comprises that drawbell development and undercutting transitions seamlessly into caving of the rock mass located above the undercut.
The free surface obtained by blasting slices of rock mass promotes efficient blasting and seamless transition to subsequent caving. Moreover, blasting of slices of rock mass in the drawbell is performed in a preferred direction which corresponds to the later caving direction. In such way a more stable initial production phase with a high caving rate is expected. Overall, the integrated development of drawbell and undercut can be regarded as simple and controllable.
Alternatively blasting takes place in a semi-confined environment by drawing previously blasted rock from the drawbell without creating a void.
In such casethere is not a void between the fragmented rock mass and the drawbell roof. Thereby, the fragmented rock mass provides support to the drawbell roof and enhances its stability. Indeed, there is not a free surface for blasting of subsequent slices anymore. Blasting takes now place against fragmented rock mass and the blast environment is therefore referred to as semi-confined. Such semi-confined blast conditions may be particularly advantageous at the time shortly before the drawbell roof area exceeds the critical area for initiation of caving. In this state, the additional support provided by the fragmented rock mass still provides a stable drawbell roof and enables blasting subsequent slices required for cave initiation.
In one embodiment of the invention, the method comprises that the shape of individual blast slices is adapted to form a drawbell of a specific predetermined shape. By drilling the boreholes in different angles, charging and blasting the boreholes, different parts of the rock mass are blasted such that a specific shape of the drawbell may be obtained.
In one embodiment of the invention, the method comprises blasting several slices in one blast shortly before cave initiation may be advantageous in this transformation stage. Blasting several slices in one blast requires appropriate timing between individual slices to achieve a satisfying blast result.
When the area of the undercut exceeds a critical area required for cave initiation, the caving process is initiated and progresses upwards.
When caving progresses further upwards a stope is formed above the drawbell. Typically, a zone of fractured rock mass forms at the cave back. A part of rock mass detaches from the in-situ rock mass and piles up in the caving stope. It is important to keep a void between the cave back and the broken mass inside the caving stope. This void is required for cave progression. Continuous draw of ore enables continuous cave progression.
To accomplish a sufficient void, a proper draw strategy must be implemented. However, the formation of excessive void leads to the risk of an air blast and must be avoided.
In one embodiment of the invention, the method comprises scheduled switching from caving to drilling and blasting in specific areas in a part of the stope for a limited time period by operating the machinery arranged inside the raise located in the rock mass. Production by caving is preferred from a cost perspective. However, intermittent drilling and blasting may be performed depending on the rock mass and the cave progression.
In one embodiment of the invention, the method comprises switching from caving to drilling and blasting on demand. In case the rock mass cannot be reliably and safely caved, or in case the ore body geometry demands it, switching to drilling and blasting may be required during a period before continuation of caving.
In one embodiment of the invention, the method comprises re-initiating caving of the stope is done by pre-breaking by drilling, charging and blasting in a part of the stope in specific areas from inside the raise by operating the machinery arranged inside the raise in case caving has stalled.
In one embodiment of the invention the method comprises joining at least two drawbells and forming a coherent stope above the drawbells and caving the coherent stope. Thereby, the undercut of the at least two drawbells are joined such that a larger unsupported area is formed. By connecting at least two drawbells, a significantly larger stope can be formed which increases production.
In one embodiment of the invention, the method comprises enlarging a caving stope in lateral direction by means of development of an additional drawbell located next to the caving stope. Preferably, the roof of the additional drawbell is connected to a caving stope, which has progressed further than said drawbell roof.
The integrated raise cavinge mining method comprises developing at least two drawpoints into the drawbell, wherein the drawpoints are arranged on different levels.
In particular, the levels are located on different elevations in relation to the drawbell. In such way the drawbell may be configured with large dimensions. The at least two drawpoints are particulary important for achieving a good ore flow in such a large scale drawbell.
The drawpoints may be arranged in a predetermined pattern for example staggered such that the material flow is stimulated to achieve an appropriate interactive draw zone. The levels may be productions levels, herein also referred to as draw levels.
Preferably, the drawpoints are developed from drifts arranged on different levels.
Preferably, at least one drawpoint is developed from a drift located on a first production level located at the bottom of the drawbell and at least one drawpoint is developed on a different production level, elevated above the first production level. Alternatively at least one drawpoint is developed from a drift arranged on a first production level located between the bottom of the drawbell and the roof of the drawbell and at least one drawpoint is developed on a different production level, elevated above the first production level. Preferably, the drifts are developed adjacent to the drawbell however the location and configuration of the drifts may be adapted to the rock mass and/ or stress situation and/ or mining layout.
Due to the shape of the drawbell, only a few drawpoints are required at the drawbell prior to initiation of caving. The blasted rock mass from drawbell development is drawn at these drawpoints. For this reason, the required infrastructure development at the production level(s) is limited in the ramp-up phase. After caving has been initiated, the remaining parts of the production level(s) are developed such as further production levels adjacent the drawbell and/or the caving stope. Thus, the requirement of infrastructure pre-development is reduced in comparison with prior art cave mining methods.
The integrated raise cavinge mining method comprises progressively drawing fragmented rock mass from the at least one drawbell through the drawpoints.
During production, caved fragmented rock mass falls into the drawbell and moves down to the drawpoints where it is drawn by suitable machinery such as loaders or continuous draw machinery with conveyors.
In one form of the invention, the method comprises developing at least one additional drawpoint into the drawbell and developing said at least one additional draw point on the same level as pre-existing drawpoints or on a different level than pre-existing drawpoints to stimulate material flow in the drawbell.
The additional drawpoint(s) may be developed after completion of the drawbell development or after caving has been initiated. Such late development protects the additional drawpoint(s) from high stresses during drawbell development and corresponding undercutting as well.
Furthermore, the position of the drawpoints may be adapted to local rock mass conditions and/ or ore flow considerations.
In one embodiment of the invention, the method comprises developing at least one additional drawpoint into the stope arranged above the drawbell. To improve the ore flow, further drawpoints may be developed into the stope above the drawbell.
In one embodiment of the invention, the method comprises adapting the position of the drawpoint(s) relative to the drawbell and/ or stope. Preferably the drawpoint(s) is (are) positioned such that ore flow is improved.
In one embodiment of the invention, the method comprises providing the drawbell with at least one additional production level having at least one drift. The additional production level may be provided with one or more additional drawpoints with drifts providing access to the drawpoints. Thus, further production levels and drawpoints may be developed and added during the mining operation, thereby reducing requirement for infrastructure pre-development and increasing flexibility.
In one embodiment of the invention, the method comprises developing at least one rock pass between at least two production levels. The rock pass is used for the transport of broken rock mass between the production levels. In deep underground mines it is common practice to transport the broken rock mass by means of gravity to the deepest level in the mine from where it is hoisted to surface.
In one embodiment of the invention, the method comprises developing said additional drawpoints from one direction into the drawbell and /or stope. Thus, since the drifts provide access to drawpoints, the drifts of the production level may be developed and oriented in required direction. The additional drawpoint may also be arranged on the same production level as an earlier developed drawpoint to improve the ore flow.
Alternatively, in one embodiment of the invention, the method comprises developing said additional drawpoints from different directions into the drawbell and /or stope, for example in opposite directions. The drifts providing access to said drawpoints should thus be oriented in different directions. The additional drawpoints may be arranged on the different production levels located on different sides of the drawbell to improve the ore flow.
To achieve favorable interactive draw improving the ore flow, drawpoints may be developed into the drawbell from different directions. Thus, the added drawpoints are then arranged on different sides of the drawbell.
In one embodiment of the invention, the mining method comprises that the location and/ or shape of at least one drawpoint is adapted to local requirements during drawing fragmented rock from the stope. Thus, the drawpoints may be moved or re-established to adapt to the situation when for examples problems with draw occur.
The application of a large sized drawbell is advantageous as it reduces the risk of hang-ups. Moreover, since at least two drawpoints which are arranged on different levels are developed into the drawbell, the drawbell is accessible which facilitates removal of hang-ups.
The large size of the drawbell and the arrangement of drawpoints on different levels enable an optimized drawpoint positioning from an ore flow perspective. Thereby, the spacing of several neighboring drawpoints can be kept constant.
Drawing broken rock mass from a drawpoint maintains a specific flow of broken rock mass inside the drawbell towards said drawpoint. However, every drawpoint maintains the flow of broken rock mass only in a certain area. This area is commonly referred to as isolated draw zone. Correspondingly, a zone of relatively stationary material characterized by insignificant flow of rock mass remains between neighboring isolated draw zones.
In one embodiment of the invention, the method comprises developing the drawpoints at selected positions into the drawbell such that isolated draw zones corresponding to the drawpoints overlap at least in some areas. Thus, there is a smaller zone of relatively stationary material between neighboring isolated draw zones. In one embodiment of the invention, the method comprises performing interactive drawing from drawpoints within an individual drawbell. The interactive draw is realized by drawing broken rock mass concurrently from neighboring or adjacent drawpoints at the same time or within a short time interval. Interactive draw has the benefit that width of the draw zone is increased. Thus, a more efficient production is achieved and dilution is delayed.
In one embodiment of the invention, the mining method comprises providing the at least one drawbell with multiple drawpoints distributed over at least two levels and distributing said drawpoints evenly such that a favorable drawpoint spacing is achieved and drawing said drawpoints interactively such that interaction between isolated draw zones is achieved.As drawpoints are drawn interactively, isolated draw zones of individual drawpoints start to interact. Consequently, broken rock mass between neighboring isolated draw zones starts to move. Therefore, an interactive draw zone develops near isolated draw zones. Preferably a uniform draw both temporarily and spatially from drawpoints is pursued to enlarge the interaction in the interactive draw zone.
In one embodiment of the invention, the method comprises performing drawing of broken rock mass interactively from at least two neighboring drawbells and forming an interactive draw zone across drawbells. Thereby, the interactive draw in each drawbell results in larger drawbell interactive zones which interact across the drawbells.
The development of drawpoints on more than one draw level provides the possibility to improve the drawpoint arrangement from an ore flow point of view.
In one embodiment of the invention, the mining method comprises developing the drawpoints in a staggered, square or rectangular layout.
The layout refers to the position of isolated draw zone centers in the horizontal plane. A staggered layout improves the volumetric coverage of the isolated draw zones.The actual arrangement of drawpoints depends on local circumstances, such as the fragmentation of rock mass, the size and shape of drawpoints, the size and shape of drawbells, or the applied draw strategy.
The large size of the drawbell furthermore enables reduction of the number of neighboring drawpoints, in particular where the drawpoint spacing is not ideal, i.e. too large, or too small. Due to the latter drawpoint positioning improvements, interactive draw is promoted and significantly improved. Accordingly, the risk of early dilution is reduced. Overall, the large sized drawbell provides improvements from an ore flow perspective, which enable a higher productivity in comparison with prior art cave mining methods.
In one embodiment of the invention, the method further comprises pre-conditioning of rock mass located above the drawbell roof by operating the machinery arranged inside the at least one raise.
In one embodiment of the invention, the method further comprises performing pre-conditioning of rock mass located where the stope is intended to be positioned by operating the machinery arranged inside the at least one raise located in the rock mass. Pre-conditioning is advantageous in that it improves caveability and fragmentation of the rock mass. Typical pre-conditioning methods include hydraulic fracturing and/or confined blasting. Pre-conditioning may be performed in a part of the rock mass located above the drawbell.
In one embodiment of the invention, the method further comprises performing pre-conditioning measures in specific areas above the drawbell roof and on-demand. The rock mass may contain particularly competent rock formations, which have to be pre-conditioned. By performing pre-conditioning from the raise, access to critical rock mass formations is improved. In particular, where the position of the competent rock mass formation is such that it is foreseen to be a part of the stope under development as caving progresses. Preferably the at least one raise intersects the ore body to be caved. Thus, the preconditioning measures may be conducted in regions where the ore body is more competent than in other regions intended to be mined. The competent rock mass formation does not cave readily and easily due to its strength and caving may stall. The pre-conditioning measures creates a pre-conditioned zone which is characterized by artificial fractures inside the rock mass and/ or by a decreased strength of natural discontinuities inside the rock mass. Accordingly, the strength of the rock mass in the pre-conditioned zone is reduced compared to its strength prior pre-conditioning.
Alternatively, pre-conditioning may be carried out by machinery arranged in a raise or a drift located outside the region intended to be mined. In one embodiment of the invention the mining method comprises performing pre-conditioning in at least some parts of the region intended to be mined.
In one embodiment of the invention, the method comprises operating the machinery arranged inside the raise for improving caveability and fragmentation of the rock mass foreseen to be a part of the stope.
In one embodiment of the invention, the method comprises performing pre-conditioning of rock mass from the raise in parallel with drawbell excavation. This means that these method steps may be performed at the same time. Alternatively, pre-conditioning may be conducted from the raise prior to drawbell development.
In one embodiment of the invention, the method comprises performing pre-conditioning of rock mass from the raise in parallel with undercutting. This is particularly advantageous in that the ramp-up time for development and production and can be shortened.
In one embodiment of the invention, the method comprises performing pre-conditioning in order to reduce the magnitude of mining-induced seismicity. This is very advantageous.
Preferably pre-conditioning and undercutting are then performed from the same raise and utilize same work processes namely machinery for drilling blast holes, charging and detonating explosive charges in those blast holes. Whilst undercutting is performed in a specific stope, pre-conditioning is conducted for the same stope at the same time. In another alternative pre-conditioning and undercutting may be alternated and performed at two different locations in a short period of time.
In one embodiment of the invention, the method comprises performing pre-conditioning of rock mass from inside the raise in parallel with caving of the caving stope below the raise. Then pre-conditioning and caving may be performed at two different locations in the stope at the same time. Alternatively, the method steps may be alternated and performed at two different locations in a short period of time. Due to pre-conditioning can the caving stope progress through the competent rock mass formation without stalling. As a result of the pre-conditioning measures applied from machinery operating inside the at least one raise, the caving progression rate and the possible production rate from the stope may be improved.
At least one monitoring system is installed in the integrated raise caving mining infrastructure. The monitoring system comprises amongst others a plurality of monitoring means, central monitoring unit, data collection units, communication devices and data analysis tools. A control system may also be installed. This control system utilizes the data and information generated by the monitoring system to control for example the machinery or production.
The at least on raise provides access into the drawbell and at later stage depending on the length of the raise the caving stope, the cave back and the rock mass above the cave back.
In one embodiment of the invention, the mining method comprises monitoring of caved rock mass by using a remote controlled monitoring device arranged inside the raise.
Monitoring means can be arranged inside the raise to monitor the mining operation, and the monitoring means can also be lowered through the raise into the cave which enables improved monitoring of for example cave back, fragmentation, fracturing zone etc. Monitoring means are for example seismic monitoring system, time domain reflectometry technology, open bore holes, cavity scanners, sensors, marker or geophones.
In one embodiment of the invention, the mining method comprises drilling boreholes into the rock mass from the raise and placing sensors in the boreholes . In addition, monitoring means can be installed in the rock mass such as markers or geophones by use of machinery operating inside the raise. This is advantageous as the raises provide improved accessibility to the rock mass of caving stopes being subsequently mined.
In one embodiment of the invention, the mining method comprises monitoring cave progression and/ or direction of cave progression.
In one embodiment of the invention, the method comprises monitoring of the caving stope and/ or the cave back and/ or the caved rock masses by remote controlled monitoring means which is lowered through the raise and into the caving stope.
In one embodiment of the invention, the mining method comprises monitoring of an advancing fracture and loosening zone located above the cave back, and registering monitoring data thereof.
In one embodiment of the invention, the method comprises using monitoring data from cave monitoring for draw management of the rock mass material.
In one embodiment of the invention, the mining method comprises adjusting a draw strategy and/ or draw control and/ or caved rock masses at the production levels based on monitoring of the caving stope, the caved masses, and/ or cave back.
The registered monitoring data may be used for controlling and adjusting a draw strategy at the production level(s) on demand and/ or flexibly. A draw strategy is advantageous in that a formation of a large void can be avoided and/ or in that extracted grades can be controlled and/ or in that the dilution can be delayed.
Additionally, the raise(s) provide a better knowledge regarding the prevailing geology and rock mass conditions. Specifically, the position and extent of certain geological formations or zones of certain and/ or similar rock mechanics behavior can be outlined.
Furthermore, monitoring and registered monitoring data allows improved understanding of the caving behavior and caveability of individual formations or zones.
In one embodiment of the invention, the method comprises controlling cave progression by performing controlling measuresfrom inside the raise. In such a way the rate of cave progression can be controlled and influenced.
In one embodiment of the invention, the method comprises controlling the direction of cave progression by performing controlling measures from inside the raise. In such a way the direction of cave progression can be controlled and influenced.
In one embodiment of the invention, the method comprises controlling cave progression by operating machinery arranged inside the raise and/ or by draw strategy and/ or draw control.
In one embodiment of the invention, the method comprises controlling the direction of cave progression by operating machinery arranged inside the raise and/ or by draw strategy and/ or draw control.
In one embodiment of the invention, the method comprises controlling the direction of cave progression by pre-conditioning specifically selected volumes of rock mass.
Preferably cave progression may be controlled by performing pre-conditioning measures specifically in critical parts of the rock mass by operation of machinery located inside the raise and/ or the applied draw strategy. Preferably, pre-conditioning measures are applied on demand.
In one embodiment of the invention, the mining method comprises determining of precondition measures based on monitoring of spatial distribution and/ or behavior of individual formations and zones.
Based on the registered monitoring data, information regarding spatial distribution, behavior of formations, and behavior of zones, pre-conditioning measures can be applied from raises at a safe distance above the actual position of the cave back.
In one embodiment of the invention, the mining method comprises performing pre-conditioning measures during ongoing undercutting and/ or ongoing caving. In such a way , there is no need to conduct the pre-conditioning before undercutting commences.
In case caving stalls, raises provide the possibility to observe the stalled area with remote controlled monitoring means. Thereby, the identification of the reasons of cave stall is facilitated. Additionally, where caving stalled, the raise provides an access for remote controlled or automated machinery into the cave back in the zone. In such a way cave stalling can be resolved by performing pre-breaking of the rock mass.
In one embodiment of the invention, the method comprises mitigating risk of air blast and/ or cave stall in the stope by using monitoring means arranged inside the raise. Preferably a remote-controlled monitoring device is lowered through the raise into the cave to directly monitor a potential cave stall and/ or air blast risk.
In one embodiment of the invention, the method comprises mitigating risk of air blast and/ or cave stall in the stope by operating machinery arranged inside the raise and /or by draw strategy and/ or by draw control.
In one embodiment of the invention, the mining method comprises that the at least one raise may also be used for performing pre-breaking measures. Thus, based upon the information from the monitoring means specific pre-breaking measures can be applied which aim for re-initiation of caving.
In one embodiment of the invention, the method comprises re-initiation of the caving by operating the machinery arranged inside the raise in case caving stalled. Preferably, re-initiation is performed by drilling and blasting of the cave back.
In one embodiment of the invention, the mining method comprises that the cave progression direction is non-vertical. The cave progression direction depends on several parameters which are, amongst others, the prevailing rock mass properties, their spatial distribution, the prevailing stress situation, the presence of large faults or shear zones, the presence of previously mined stopes, and the implemented draw strategy.
Different methods may be applied to control the direction of cave progression such as pre-conditioning, pre-breaking, and/ or draw strategies can be used to control the direction of cave progression.
In one embodiment of the invention, the mining method comprises controlling the direction of cave progression.
In one embodiment, the draw strategy may be adapted in order to direct the cave progression in a preferred direction.
In one embodiment of the invention, the mining method comprises controlling the direction of cave progression by pre-conditioning specifically selected volumes of rock mass. In particular, pre-conditioning measures may be applied to control the direction of cave progression near a weak rock mass formation and/ or large faults and/ or shear zones.
Overall, the application of raises provides a better controllability and thereby improves the operation. Moreover, the integrated raise caving mining method may thus be applied to more difficult mining environments for caving operations. Such mining environments comprise for example deep ore bodies, competent rock masses, or geometrically constrained ore bodies.
In one embodiment of the invention, the method comprises that a mining sequence is adapted to and determined by production and/ or ore body geometry and/ or rock mechanics consideration and/ or ore flow considerations. The mining sequence determines the order of mining activities which should be followed to achieve the overall goals of mineral extraction of the ore body. The goals are an as complete extraction as possible, the safety and economy of the mining operation considering rock mechanical constraints, and other factors.
In one embodiment of the invention, the method comprises that the mine layout and infrastructure position are adapted to and determined by production and/ or ore body geometry and/ or rock mechanics consideration and/ or ore flow considerations.
In one embodiment of the invention, the method comprises that the mine layout and/or infrastructure position and/or mining sequence are adjusted on short notice. In such case unforeseen circumstances can be taken into account.
In one embodiment of the invention, the method comprises performing parallel infrastructure development and production ramp-up. This is advantageous in that mining layout and sequence of the integrated mining method allow that production can be ramped-up simultaneously with the infrastructure development. This is cost efficient and shortens the time until production.
In one embodiment of the invention, the method comprises that after caving reached the ore body boundaries, waste rock mass from the surrounding and/ or overlying rock mass formations caves into the stope.
In one embodiment of the invention, the method comprises that in the process of drawing remaining ore from the stope, the stope is subsequently filled with waste rock mass.
In one embodiment of the invention, the method comprises connecting the caving stope to a formerly mined out area. Alternatively, the caving stope may be connected to the surface which causes subsidence.
From a rock mechanics point of view, the development of a drawbell from at least one raise and the associated undercutting is particularly advantageous. The required infrastructure for drawbell development and undercutting is limited. Moreover, infrastructure required for undercutting may be situated in a more favorable stress environment. Accordingly, possible damage to infrastructure can be limited. Moreover, personnel does not need to work in high stress zones. As the drilling, charging and blasting work in the raise can easily be remote controlled, or automated, workforce may be removed from hazardous areas completely.
Another rock mechanics advantage is the improved strength of production level(s). The presence of the large drawbell and the arrangement of drawpoints on several levels enable the creation of large pillars with considerable strength between neighboring drifts and drawpoints. Moreover, due to the development of most of the production level infrastructure after drawbell construction and undercutting, production level infrastructure is developed delayed and corresponding pillars are not exposed to high stresses during undercutting. Therefore, rock mass damage can be reduced, and stability be increased.
Overall, the integrated raise caving mining method offers significant advantages from a rock mechanics point of view. These advantages manifest themselves in an improved safety, a reduced risk and an improved stability.
In one embodiment of the invention, the method comprises that the stope generates a stress-shadow at certain locations adjacent to the stope, wherein said stress-shadow de-stresses the rock mass thereby creating a favorable stress environment.
In one embodiment of the invention, the method comprises that the interaction between at least two adjacent stopes generate a regional favorable stress environment for mining infrastructure.
In one embodiment of the invention, the method comprises that raises, drifts, drawpoints and other infrastructure are developed in a favorable stress environment at locations adjacent to drawbells and/ or stopes.
In one embodiment of the invention, the method comprises repeating the steps of the method to a larger area.
These or at least one of said objects are achieved by use of the integrated raise caving mining method for mining of ore from a deposit where cave mining methods such as block caving, panel caving, inclined caving, or raise caving are applied as claimed in claim 57.
Certain elements of the integrated raise caving mining method according to the invention could be applied in prior art caving methods. For example, neighboring stopes mined by raises could replace a traditional flat undercut in block and panel caving. In such way, the size of the stope roof would be increased, until caving is initiated. Moreover, raises equipped with appropriate machinery above an active cave would provide possibilities for pre-conditioning, cave advance monitoring, facilitation of cave advance and control of caving front.
These or at least one of said objects are achieved by an integrated raise caving mining infrastructure configured for mining deposits in a rock mass as claimed in claim 58 wherein further embodiments are incorporated in the dependent claim.
Hence, according to one aspect the present invention relates to an integrated raise caving mining infrastructure that comprises: at least one raise developed in the rock mass; a drawbell developed in the rock mass, wherein at least a portion of the drawbell is joined to the at least one raise; an undercut being configured to initiate caving of rock mass located above the undercut, wherein at least a portion of the undercut is formed as a part of the drawbell; wherein said portion has been created by gradually expanding the drawbell in upward direction by excavation; at least two drawpoints joined to the drawbell, wherein the drawpoints are joined to drifts arranged on different levels; and a transport device configured to progressively draw fragmented rock from the drawbell.
Alternatively, the integrated cave mining infrastructure comprises a caving stope located above the drawbell.
It should be noted that more than one integrated raise caving mining infrastructures may be present in the same active mining area.
These or at least one of said objects are achieved by a monitoring system as claimed in claim 60, wherein further embodiments are incorporated in the dependent claims.
Hence, according to one aspect the present invention relates to a monitoring system configured for monitoring an integrated raise caving mining infrastructure configured for mining deposits in rock mass, which monitoring system comprises monitoring means configured for monitoring development of at least one raise developed in the rock mass ; and/ or monitoring means configured for monitoring development of a drawbell developed in the rock mass , wherein at least a portion of the drawbell is joined to the at least one raise; monitoring means configured for monitoring development of an undercut being configured to initiate caving of rock mass located above the undercut, wherein at least a portion of the undercut is formed as a part of the drawbell; wherein said portion has been created by gradually expanding the drawbell in upwards direction by excavation; and/ or monitoring means configured for monitoring development of at least two drawpoints joined to the drawbell, wherein the drawpoints are joined to drifts arranged on different levels; and/ or monitoring means configured for monitoring the initiation of caving of the rock mass; and/or monitoring means configured for monitoring of a transport device configured to progressively draw fragmented rock from the drawbell; and/ or monitoring means configured for monitoring the rock mass in the active area; and/ or monitoring means configured for monitoring the caving stope
Alternatively, the monitoring system is configured for monitoring cave progression and/ or direction of cave progression. Alternatively, the monitoring system is configured for monitoring of caved rock mass by using a remote controlled monitoring device arranged inside the raise. Alternatively, the monitoring system is configured for remotely monitoring of the caving stope and/ or the cave back and/ or the caved rock masses.Alternatively, the monitoring system is configured for monitoring an advancing fracture and loosening zone located above the cave back. Alternatively, the monitoring system is configured for monitoring seismicity and/ or stress and/ or deformations in the rock mass wherein the integrated raise caving mining infrastructure is located. Alternatively, the monitoring system is configured for collecting monitoring data, analysing monitoring data, storing monitoring data and/or transmitting monitoring data via wireless and/or wired communication means to an automatic or semi-automatic control system of an integrated raise caving mining infrastructure.
The monitoring system comprises amongst others a plurality of monitoring means, a central monitoring unit, data collection units, data storage means, communication devices for wireless communication of signals and monitoring data and/or data analysis tools. The monitoring system is configured to communicate with the automatic or semi-automatic control system and transmits data and information generated by the monitoring system to the automatic or semi-automatic control system. The monitoring means comprises for example seismic monitoring system, time domain reflectometry technology, open bore holes, cavity scanners, sensors, marker or geophones.
These or at least one of said objects are achieved by a machinery as claimed in claim 64, wherein further embodiments are incorporated in the dependent claims.
Hence, according to one aspect the present invention relates to a machinery comprising a drilling and/or charging device configured for; developing at least one raise in the rock mass; and/or developing a drawbell in the rock mass, wherein at least a portion of the drawbell is excavated from the raise by drilling and/or charging by means of the machinery, thereby initiating caving through undercutting; developing the drawbell by gradually expanding the drawbell in upwards direction by excavation; and/ or developing at least two drawpoints into the drawbell, wherein the drawpoints are developed from drifts arranged on different levels; and/or transporting fragmented rock from the drawbell through the drawpoints.
Alternatively, the machinery is configured for drilling and/or charging the rock mass from inside the raise. Alternatively, the drilling and/or charging device comprises a drilling bore and/or charging equipment configured for initiating said caving. Alternatively, the machinery comprises pre-conditioning equipment. Alternatively, the machinery comprises that the drilling and/or charging device is arranged on a movable platform, which is movable within the raise for reaching a position for operation of the drilling and/or charging device.
Alternatively, the machinery comprises that the platform is configured with a modular design. Alternatively the machinery and/or equipment arranged on the platform is configured with a modular design. Alternatively, the machinery comprises that the platform is configured to be moved to the side at the top of the raise to be stored in a storage position.
Alternatively, the machinery is configured for installing rock support from inside the raise, such as rock bolts, mesh, shotcrete or cable bolts. Alternatively, the machinery is configured for hydrofracturing the rock mass from inside the raise.Alternatively, the machinery is configured for performing directional drilling. Alternatively, the machinery is configured for drilling curved boreholes by directional drilling. Alternatively, the machinery is configured for blast initiation of the charged boreholes. Alternatively, the machinery is configured for for blast initiation from inside the raise. Alternatively, the machinery is configured for blast initiation by wired detonators and/ or remote-controlled detonators and/ or non-electric detonators and/ or wireless detonators. Alternatively, the machinery is configured for loading and transporting fragmented rock from the drawpoints by loaders and/ or trucks and/ or continuous draw machinery with conveyours. Alternatively, the machinery is configured to be operated by remote control and/ or by manual control.Alternatively, the machinery is configured for semiautomation or full automation.
Alternatively, the integrated raise caving mining infrastructure comprises the machinery according to any of claims 64 to 81.
Alternatively, the integrated raise caving mining infrastructure comprises the monitoring system according to any of claims 60 to 63.
These or at least one of said objects are achieved by an automatic or semi-automatic control system as claimed in claim 84, wherein further embodiments are incorporated in the dependent claims.
Hence, according to one aspect the present invention relates to an automatic or semi-automatic control system of an integrated raise caving mining infrastructure according to claims 58 or 59, wherein the automatic or semi-automatic control system is electrically coupled to a control circuitry configured to control the method according to any of claims 1 to 56.
Alternatively, the automatic or semi-automatic control system comprises said machinery according to any of claims 64 to 81, wherein the machinery is configured to be operated by the automatic or semi-automatic control system in remote control mode and/or in automatic control mode and/or in semi-automatic control mode and/or manually controlled mode.
Alternatively the automatic or semi-automatic control system comprises the monitoring system (920) according to any of claims 60 to 63, wherein the monitoring system is configured to communicate with and be operated by the automatic or semi-automatic control system in remote control mode and/or in automatic control mode and/or in semi-automatic control mode and/or manually controlled mode.
Alternatively the integrated raise caving mining infrastructure comprises the automatic or semi-automatic control system according to any of claims 84 to 86.
These or at least one of said objects are achieved by a data medium as claimed by claim 88, wherein further embodiments are incorporated in the dependent claims.
Hence, according to one aspect the present invention relates to a data medium, configured for storing a data program, configured for controlling the automatic or semi-automatic control system according to any of claims 84 to 86 and/or configured for controlling the machinery according to any of claims 64 to 81, said data medium comprises a program code readable by the control circuitry for performing the method according to any of claims 1 to 56 when the data medium is run on the control circuitry.
Overall, the integrated raise caving mining method and the raise caving mining infrastructure, the machinery, the monitoring system, the the automatic or semi-automatic control system and the data medium offers significant advantages from a rock mechanics point of view. These advantages manifest themselves in an improved safety, a reduced risk, and an improved stability. The integrated raise caving mining method and the raise caving mining infrastructure, the machinery, the monitoring system, the the automatic or semi-automatic control system and the data medium according to the invention offers considerable flexibility. The amount of infrastructure required for development of a caving stope and ramp-up of production is reduced. The combined use and sharing of infrastructure for the implementation of undercutting, production (caving), and pre-conditioning enables the latter circumstance. The remaining portions of the infrastructure can be developed after drawbell development and undercutting are completed. The limited amount of infrastructure pre-development enables to decide on the position of subsequent drawbells, raises, drawpoints etc. on short notice, which contributes to the flexibility of the integrated raise caving mining method significantly. Moreover, the position, size, shape, and orientation of drawbells, drawpoints, raises, and other infrastructure can be adapted to local conditions and/ or requirements.
Overall, the flexibility of the integrated raise caving mining method and the raise caving mining infrastructure, the machinery, the monitoring system, the the automatic or semi-automatic control system and the data medium offers considerable improvements. The mine layout and mining sequence can be adopted to the prevailing mining environment, which comprises amongst others the prevailing stress situation, the prevailing rock mass formations, and the ore body shape on short notice. Thereby, the integrated raise caving mining method and the raise caving mining infrastructure, the machinery, the monitoring system, the the automatic or semi-automatic control system and the data medium enables the avoidance of critical situations and the relatively easy adaption to unforeseen circumstances. Moreover, possibly available favorable stress environments which are provided by caving stopes may be used for protection of infrastructure. In summary, the available flexibility contributes to the reduction of risks considerably.
Above outlined technical advantages achieved by the integrated raise caving mining method, the raise caving mining infrastructure, the machinery, the monitoring system, the the automatic or semi-automatic control system and the data medium according to the present invention may result in some or all of the following overall improvements compared to prior art caving methods.
In conclusion, these improvements facilitate the goals of mineral extraction, which are a safe, as complete as possible, and profitable extraction. In some instances, this will also enable the extraction of mineral deposits by a caving method, which cannot be mined by a prior art caving method.
In this specification the following terms and expressions are defined as below and are used accordingly.
The term “ore” refers to a mineral aggregate of sufficient value as to quality and quantity to be mined at a profit. The prevailing definition of ore does not only comprise metal ore, but any other mineral aggregates, for example industrial minerals etc.
The term “ore body” refers to a volume of rock mass containing ore. In this specification the term “deposit” is used synonymously for ore body.
The term “stope” refers to the part of the ore body, from which ore is currently being mined or broken by stoping. The term “stoping” includes all operations of breaking rock or mineral for example by drilling and blasting, mechanical excavation and/or caving, and extracting rock or mineral in stopes, after breaking.
The term “caving stope” refers to a stope, which is excavated by means of caving. The term “cave” is used synonymously for the term caving stope.
The term “undercut” refers to a void created in the rock mass with the objective of cave initiation. The term “undercutting” refers to removal of a section or kerf in a rock mass to initiate caving subsequently.
“Active mining areas” are areas of significant and ongoing stress changes resulting from mining activities in the area. These are predominately but not exclusively the extraction (stoping) areas. The heading of tunnels under development are also active areas but on a localized scale. Active mining areas require ongoing supervision, monitoring of ground conditions and attention to excavation support. As mining advances active areas change to passive areas which require reduced levels of supervision and monitoring except for main transport and regularly used infrastructure excavations.
The expression “mining sequence” refers to the sequence of mining activities which should be followed to achieve the overall goals of extraction of the ore body as complete as possible, the safety and economy of the mining operation, considering operational factors, rock mechanical constraints, and other factors.
The expression “favourable stress environment” refers to a stress state which is controllable and which does not require extensive and expensive support measures for subsequent operation in the respective mining area. A favourable stress environment could be either a de-stressed area in a rock mass, or an abutment area where abutment stresses are limited or restricted to a controllable magnitude. The favourable stress environment serves the purpose to create a favourable environment for the subsequently establishment of raises and the subsequent operation in the production stopes and where possible mine infrastructure with a long lifetime. The term “favourable stress situation” is used synonymously. From the above follows that the term “de-stressing” refers to the process of creating a de-stressed environment in the rock mass i.e. a stress-shadow.
The term “stress-shadow” refers to a part of the rock mass where the stress is reduced in at least one direction in comparison with the pre-mining rock stress in corresponding direction in the same part of the rock mass.
The term “raise” refers to a longitudinally extended vertical or inclined mine infrastructure opening.
The term “rock pass” refers to steeply inclined passage-ways used for the transfer of material in underground mine workings. Rock passes are designed to utilize the gravitation potential between levels to minimize haulage distances and facilitate a more convenient material handling system. The term “ore pass” refers to rock passes that are solely used for the transport of ore. In deep mines it is common practice to gravitate the ore to the deepest level in the mine from where it is hoisted to surface.
The terms “tunnel” and “drift” are herein used as synonyms and refer to same type of infrastructure.
The term “pre-conditioning” refers to a technique to increase the in-situ fragmentation of the rock mass so that it will cave or fragment more readily.
The term “pre-break” refers to a technique which may be specifically used in a competent zone to re-initiate caving to progress through this zone with the stope.
The term “dilution” refers to a contamination or mixing of worthless rock mass with ore.
The term “drawpoint” refers to an excavated structure through which the caved or broken rock mass is removed from the stope and/ or drawbell.
The term “drawbell” refers to an excavated structure which channels caved or broken rock mass to at least one drawpoint.
The term “draw zone” refers to the zone of caved or broken rock mass that will eventually report to a particular drawpoint during progressive draw. The “isolated draw zone” refers to the draw zone isolated from other draw zones as a result of drawing from an isolated drawpoint. The “interactive draw zone” refers to the zone in-between isolated draw zones which are drawn concurrently such that the rock mass flows towards drawpoints and leads to an enlargement of isolated draw zones. The advantage with an “interactive draw zone” is that the ore losses are reduced compared to isolated draw zones. The broken ore in adjacent draw zones may migrate from one draw zone to the other.
The term “mass flow” refers to the mechanism by which a volume of broken or caved rock mass moves downwards uniformly during draw. The presence of interactive draw further fosters mass flow. Thereby the risk for dilution is reduced.
Caving operations require a “draw strategy” in which the draw is spatially and temporally planned for the given drawpoints. This process needs to be controlled operationally and may be referred to as “draw control” for which the amount and properties of ore drawn from individual drawpoints are registered. The observations from draw control can in turn be used again to adapt the applied draw strategy.
It should be noted that the the expressions “flow of ore”, “material flow”, “flow of fragmented rock” is used synonymously in this specification.
Additional objects, advantages, and novel features of the present invention will become apparent to one skilled in the art from the following details and through exercising the invention. Whereas examples of the invention are described below, it should be noted that the invention may not be restricted to the specific details described.
To fully understand the present invention and further objects and advantages of it, the detailed description set out below should be read together with the accompanying drawings, in which the same references denote similar features in the various figures, and in which:
Examples and embodiments of the integrated raise caving mining method, the mine layout, and the mining sequence according to the present invention, will be described in the following with references to the figures.
For purpose of simplicity the rock mass is not shown in the figures but rather the raises, drawbells and drawpoints developed in the rock mass.
One important feature of the integrated raise caving mining method is the development of at least one drawbell from at least one raise and its successive transition to a caving process above the drawbell.
The shaft hoist system 104 is located in a specifically excavated infrastructure excavation, which size and shape is adapted to the requirements of the hoist system and/ or rock mechanics considerations. In order to keep the infrastructure excavation of the hoist system 104 small, a modular design of the platform 103 and/ or machinery 120 mounted on the platform is advantageous. A small infrastructure excavation provides an improved stability. The modular design allows changing of utilized machinery quickly.
The machinery 120 mounted onto the platform 103 is adapted to operational requirements. Possible types of machinery comprise amongst others machinery for drilling, machinery for charging, machinery for support installation or machinery for hydraulic fracturing.
As shown in
In another form of the invention, the platform 103 may also be stored by moving it aside from the top of the raise 102. Thus the platform is configured to be moved to the side at the top of the raise to be stored in a storage position.
The blast initiation can be carried out with different options, which comprise amongst others non-electric detonators, detonators initiated through an electric signal transferred via cable or detonators initiated wirelessly by means of communication through rock mass.
In another form of the invention, more than one slice could be blasted in a single blast. Thereby an appropriate time delay between individual slices is required.
In the attached figures it should be noted that the shape of the drawbells and caving stopes are only schematic illustrations which are very much idealized for the purpose of simplification.
Furthermore, features like excavations, main infrastructure, hoist shafts, ore handling facility etc. which are required in all mining methods, are not shown.
In
Consequently, a void 109 is created above the broken rock mass 101. This void 109 is required for cave progression. Rock mass from the zone of fractured rock mass 108 detaches and falls into the void. Broken rock mass 101 is finer than the in-situ rock mass and/ or rock mass in the fractured zone 108. Moreover, further comminution processes occur in the broken rock mass 101 which reduces particle size as broken rock mass flows towards the drawpoints 106.
Preferably, the drawbell 100 is configured to be oriented such that the infrastructure is positioned favorably related to the prevailing stress situation. However, in another alternative, the drawbell 100 is configured to be oriented such that cave initiation is facilitated by the prevailing stress situation.
In another embodiment of the invention, a caving stope may also be connected to a formerly mined out area or to the surface, which causes subsidence.
In
In
In
As drawing of rock mass through drawbells continues, caving progresses into the waste rock mass, which starts to fill up the stope. Drawpoints and the corresponding drawbell are put out of operation and abandoned, after an unacceptable content of waste rock mass reports to the drawpoint. Accordingly, the affected drawbell is said to be depleted.
In another embodiment of the invention, adjacent drawbells may be configured such that they are of different shape and/ or size and/ or such that they are situated at different elevations.
The direction of cave progression as shown in
Due to the pre-conditioning of specifically selected volumes of rock mass the rate of cave progression can be maintained and/ or increased in the competent zone, and caving is able to progress through the competent rock mass formation 111 without stalling.
The drawbell 100 and stope 110 illustrated in
Observations during development and operation inside raises in the present cave mining method according to the invention may be used for identification of competent rock mass formation requiring pre-conditioning. Moreover, raises enable to access critical rock mass formations to apply pre-conditioning measures selectively and on-demand. Due to the availability of raises pre-conditioning measures may be applied at the same time to drawbell development from said raise and/ or to caving of corresponding stope.
However, in another embodiment of the invention, pre-conditioning measures applied from machinery operating inside raises may be used to improve caving rate and thus the possible production rate from a stope.
In
However, in another embodiment of the invention other pre-breaking measures than drilling and blasting may be applied.
Thereby, drawbell shapes may be chosen flexibly in order to meet requirements and prevailing mining environment.
However, in other embodiments of the invention, the drawbells may be of other shape.
As caving progresses, the mined-out caving stopes may provide a stress shadow and, in specific parts of the rock mass, a favourable stress environment. Infrastructure for further drawbell and stope development, such as for example raises, drifts, or drawpoints may be positioned in these stress shadows, thereby protected from high stresses.
Stopes 310a,310b,310c,310d have been undercut and caving progresses. The stopes are filled with broken rock mass 301. In parallel, drawbells 300e,300f are developed from raises 302e,302f. The drawbells are shown as hatched lines, as drawbells are not visible in the shown cross-section, but rather located at predefined elevation below the shown cross-section. Thus, the hatched lines indicate the development and position of drawbells 300e,300f. Another raise 302g has also been developed for subsequent development of the corresponding drawbell.
Finally, the
Moreover,
The zone of competent rock mass 411 does not extend in the area above raise level 441. There was no requirement for pre-conditioning in the area above raise level 441. For this reason, raise level 441 is located closer to the draw level 431, which is used for drawbell development, so that costs for infrastructure development can be reduced. Consequently, the position of raise levels and infrastructure in the integrated raise caving mining method can be adapted to local conditions.
Drawpoints 406 are located at the production levels 431,432. Drawpoints situated at production level 432 located above level 431 were developed delayed. This means that drawpoints 406 at the production level 432 were developed into the drawbells 400a,400b after drawbell development was completed and after caving was initiated. This delayed drawpoint development enables to protect drawpoints from high stresses during drawbell development and associated undercutting as well as to position the drawpoints 406 according local rock mass conditions and ore flow considerations. Moreover, drawpoints 406 were developed into drawbells 400a,400b in different directions. Overall, the development of drawpoints 406 on more than one draw levels provides the possibility to improve the drawpoints arrangement from an ore flow point of view.
The example of the invention as shown in
Overall,
However, in another embodiment of the invention drawpoints may be arranged such that their isolated draw zones overlap at least in some areas. Thus, there is smaller zone of relatively stationary material between neighboring isolated draw zones.
However, in another embodiment of the invention, drawbells may be arranged such that the interactive draw zones from drawbells overlap at least in some areas.
However, in another embodiment of the invention, the drawpoints may be arranged in other layouts, for example a staggered or rectangular layout. The actual arrangement of drawpoints depends on local circumstances, for example the fragmentation of rock mass, the size and shape of drawpoints, the size and shape of drawbells, or the applied draw strategy.
Draw strategy is considered important for controlling the cave progression and direction, because it governs the development of the void below the zone of fractured rock mass and the broken rock mass inside the stope. Moreover, information gained from monitoring the cave back and broken rock mass pile from raises may be used to adopt the draw strategy appropriately, flexibly, and on short notice.
Alternatively, a caving stope (not shown) is located above the drawbell 100. The drawbell of the integrated raise caving mining infrastructure 902 may have other shapes than that shown in the figure.
The integrated raise caving mining infrastructure 902 may further comprise a machinery 910 that may comprise a drilling and/or charging device (not shown) configured for developing the raise 102 in the rock mass 10. The machinery 910 is configured for developing the drawbell 100 in the rock mass 10, wherein at least a portion of the drawbell is excavated from the raise by drilling,and/ or charging by means of the machinery 910, thereby initiating caving through undercutting. The machinery 910 is configured for developing the drawbell by gradually expanding the drawbell in upwards direction by excavation and for developing the at least two drawpoints 106 into the drawbell 100, wherein the drawpoints 106 are developed from drifts arranged on different levels. The machinery 910 may comprise the transport device 904 configured for transporting fragmented rock from the drawbell 100 through the drawpoints 106.
The machinery 910 may be configured to be operated by the automatic or semi-automatic control system 901 in remote control mode and/or in automatic control mode and/or in semi-automatic control mode.
The machinery 910 may be configured for drilling and/or charging the rock mass from inside the raise 102. The machinery 910 may comprise a drilling bore and/or charging equipment configured for initiating said caving. The machinery 910 may comprise pre-conditioning equipment. The machinery 910 may comprise that the drilling and/or charging device is arranged on a movable platform, which is movable within the raise 102 for reaching a position for operation of the drilling and/or charging device. The machinery 910 may comprise that the platform is configured with a modular design. The machinery 910 may comprise that the platform is configured to be stored by moving it aside from the top of the raise. The machinery 910 and/or equipment arranged on the platform may be configured with a modular design. The machinery 910 may be configured for installing rock support and/or rock reinforcement from inside the raise 102, such as rock bolts, mesh, shotcrete, cable bolts. The machinery 910 may be configured for hydrofracturing the rock mass from inside the raise 102. The machinery 910 may be configured for performing directional drilling. The machinery 910 may be configured for drilling curved boreholes by directional drilling. The machinery 910 may be configured for blast initiation of the charged boreholes. The machinery 910 may be configured for blast initiation from inside the raise 102. The machinery 910 may be configured for blast initiation by wired detonators and/ or remote-controlled detonators and/ or non-electric detonators and/ or wireless detonators. The machinery 910 may be configured for transporting fragmented rock 101 continuous draw machinery with conveyors and/or trucks and/ or loaders.The machinery 910 may be configured to be operated by remote control. The machinery 910 may be configured for semiautomation or full automation. The machinery 910 may be configured to be operated manually.
The integrated raise caving mining infrastructure 902 may further comprise a monitoring system 920 configured for monitoring an integrated raise caving mining infrastructure 902 configured for mining deposits in rock mass.
The monitoring system 920 comprises monitoring means configured for monitoring development of at least one raise 102, 102a-f, 202, 302a-g, 402a-e developed in the rock mass 10. The monitoring system 920 comprises monitoring means configured for monitoring development of a drawbell 100, 100a-c, 200a-g, 300a-f, 400a-e in the rock mass 10, wherein at least a portion of the drawbell is joined to the at least one raise 102, 102a-f, 202, 302a-g, 402a-e. The monitoring system 920 comprises monitoring means configured for monitoring development of an undercut (UC) being configured to initiate caving of rock mass located above the undercut, wherein said portion has been created by gradually expanding the drawbell in upward direction by excavation. The monitoring system 920 comprises monitoring means configured for monitoring initiation of caving. The monitoring system 920 comprises monitoring means configured for monitoring development of at least two drawpoints 106, 206, 406 wherein the drawpoints 106 are joined to drifts 115,207,407 arranged on different levels. The monitoring system 920 may be configured for monitoring of a transport device 904 configured to progressively draw fragmented rock (101) from the drawbell. The monitoring system 920 may be configured for monitoring cave progression and/ or direction of cave progression.The monitoring system 920 may be configured for monitoring of caved rock mass by using a remote controlled monitoring device arranged inside the raise. The monitoring system 920 may be configured for remotely monitoring of the caving stope and/ or the cave back (119) and/ or the caved rock masses (101). The monitoring system 920 may be configured for monitoring an advancing fracture and loosening zone located above the cave back. The monitoring system 920 may be configured for monitoring seismicity and/ or stress in the deposit wherein the integrated raise caving mining infrastructure 902 is located. The monitoring system 920 may be configured for collecting monitoring data, analysing monitoring data, storing of monitoring data, and/or transmitting monitoring data via wireless communication means to an automatic or semi-automatic control system 901 of an integrated cave mining infrastructure 902.
The monitoring system 920 comprises amongst others a plurality of monitoring means, a central monitoring unit, data collection units, data storage means, communication devices and/or data analysis tools. The monitoring system 920 may be configured to communicate with the automatic or semi-automatic control system 901 and to transmit data and information generated by the monitoring system to the automatic or semi-automatic control system 901. The monitoring means comprises for example seismic monitoring system, time domain reflectometry technology, open bore holes, cavity scanners, sensors, marker or geophones.
The method comprises a first step 801 starting the method. A second step 802 comprises developing at least one raise in the rock mass. A third step 803 comprises developing a drawbell in the rock mass, wherein at least a portion of the drawbell is excavated from the at least one raise by drilling and charging by operating a machinery arranged inside the at least one raise and thereafter blasting. A fourth step 804 comprises excavation for developing a roof area of the drawbell being larger than a bottom area of the drawbell. A fifth step 805 comprises initiating caving through undercutting, wherein at least a part of an undercut is created by gradually expanding the drawbell in upwards direction by excavation. A sixth step 806 comprises developing at least two drawpoints into the drawbell, wherein the drawpoints are developed from drifts arranged on different levels. A seventh step 807 comprises progressively drawing fragmented rock from the at least one drawbell through the drawpoints. An eight step 808 comprises initiating caving when the undercut area exceeds a critical area. A ninth step 809 comprises caving the rock mass located above the drawbell, thereby forming a caving stope. A tenth step 810 may comprise pre-conditioning of rock mass located above the drawbell roof by operating a machinery arranged inside the at least one raise. An eleventh step 811 may comprise pre-breaking of rock mass located above the drawbell roof by operating a machinery arranged inside the at least one raise. A twelfth step 812 may comprise a switching from caving to drill and blast for a specific area in the stope. A thirteens step 813 comprises stopping the method.
The control circuitry 900 is electrically coupled to a machinery (not shown) comprising a drilling and/or charging device (not shown). The control circuitry 900 is further configured to communicate with the monitoring system 920 via wired and/ or wireless communication system to transmit and/or receive monitoring data. The control circuitry 900 is configured to provide that the automatic or semi-automatic control system 901 and/or machinery each performs the method of developing at least one raise in the rock mass, developing a drawbell in the rock mass, wherein at least a portion of the drawbell is excavated from the at least one raise by drilling, charging and blasting by operating a machinery arranged inside the at least one raise, initiating caving through undercutting, wherein at least a part of an undercut is created by gradually expanding the drawbell in upwards direction by excavation, developing at least two drawpoints into the drawbell, wherein the drawpoints are developed from drifts arranged on different levels, progressively drawing fragmented rock from the at least one drawbell through the drawpoints.
The control circuitry 900 may thus also be configured for manoeuvring a transport device, such as a remote-controlled loading device, or continuous draw machinery with conveyors in a drift (not shown). The control circuitry 900 comprises a computer and a non-volatile memory NVM 1320, which is a computer memory that can retain stored information even when the computer is not powered.
The control circuitry 900 further comprises a processing unit 1310 and a read/write memory 1350. The NVM 1320 comprises a first memory unit 1330. A computer program (which can be of any type suitable for any operational data) is stored in the first memory unit 1330 for controlling the functionality of the control circuitry 900. Furthermore, the control circuitry 900 comprises a bus controller (not shown), a serial communication unit (not shown) providing a physical interface, through which information transfers separately in two directions.
The control circuitry 900 may comprise any suitable type of I/O module (not shown) providing input/output signal transfer, an A/D converter (not shown) for converting continuously varying signals from a sensor arrangement (not shown) of the control circuitry 900 configured to determine actual status of the machinery and/or the automatic or semi-automatic control system 901. The control circuitry 900 is configured to, from received control signals, determine the positions of the machinery regarding drilling and operation of the explosive material charging into binary code suitable for the computer, and from other operational data.
The control circuitry 900 also comprises an input/output unit (not shown) for adaptation to time and date. The control circuitry 900 comprises an event counter (not shown) for counting the number of event multiples that occur from independent events in operation of the machinery and/or the automatic or semi-automatic control system 901.
Furthermore, the control circuitry 900 includes interrupt units (not shown) associated with the computer for providing a multi-tasking performance and real time computing. The NVM 1320 also includes a second memory unit 1340 for external sensor check of the sensor arrangement.
A data medium for storing a program P may comprise program routines for automatically adapting the operation of the machinery and/or the automatic or semi-automatic control system 901 in accordance with operational data regarding e.g. the actual status of gradually expanding the drawbell in upward direction by excavation.
The data medium for storing the program P comprises a program code stored on a medium, which is readable on the computer, for causing the control circuitry 900 to perform the method and/or method steps described herein.
The program P further may be stored in a separate memory 1360 and/or in the read/write memory 1350. The program P, in this embodiment, is stored in executable or compressed data format.
It is to be understood that when the processing unit 1310 is described to execute a specific function that involves that the processing unit 1310 may execute a certain part of the program stored in the separate memory 1360 or a certain part of the program stored in the read/write memory 1350.
The processing unit 1310 is associated with a data port 1399 adapted for electrical data signal communication via a first data bus 1315 provided to be coupled to the machinery and/or the automatic or semi-automatic control system 901 for performing any of the exemplary method steps herein described.
The non-volatile memory NVM 1320 is adapted for communication with the processing unit 1310 via a second data bus 1312. The separate memory 1360 is adapted for communication with the processing unit 610 via a third data bus 1311. The read/write memory 1350 is adapted to communicate with the processing unit 1310 via a fourth data bus 1314. After that the received data is temporary stored, the processing unit 1310 will be ready to execute the program code, according to the above-mentioned method.
Preferably, signals (received by the data port 1399) comprise information about operational status of the machinery and/or the automatic or semi-automatic control system 901.
Information and data may be manually fed, by an operator, to the control circuitry 900 via a suitable communication device, such as a computer display or a touchscreen. The exemplary methods herein described may also be partially executed by the control circuitry 900 by means of the processing unit 1310, which processing unit 1310 runs the program P being stored in the separate memory 1360 or the read/write memory 1350. When the control circuitry 900 runs the program P, anyone of the exemplary methods disclosed herein will be executed.
The foregoing description of the preferred embodiments is provided for illustrative and descriptive purposes. It is not intended to be exhaustive, or to limit the embodiments to the variants described. Many modifications and variations will obviously be apparent to one skilled in the art. The embodiments have been chosen and described to best explain the principles and practical applications, and hence make it possible for specialists to understand the invention for various embodiments and with various modifications that are applicable to its intended use.
The present invention is of course not in any way restricted to the examples described above, but many possibilities to modifications, or combinations of the described embodiments thereof should be apparent to a person with ordinary skill in the art without departing from the basic idea of the invention as defined in the appended claims.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2050595-4 | May 2020 | SE | national |
| 2150606-8 | May 2021 | SE | national |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/SE2021/050477 | 5/20/2021 | WO |
