SE2130072A1 - Mining method for mining ore from an ore body P - Google Patents
Mining method for mining ore from an ore body PInfo
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- SE2130072A1 SE2130072A1 SE2130072A SE2130072A SE2130072A1 SE 2130072 A1 SE2130072 A1 SE 2130072A1 SE 2130072 A SE2130072 A SE 2130072A SE 2130072 A SE2130072 A SE 2130072A SE 2130072 A1 SE2130072 A1 SE 2130072A1
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- slot
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- raise
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- 238000005065 mining Methods 0.000 title claims abstract description 210
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Classifications
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- E—FIXED CONSTRUCTIONS
- E21—EARTH OR ROCK DRILLING; MINING
- E21C—MINING OR QUARRYING
- E21C41/00—Methods of underground or surface mining; Layouts therefor
- E21C41/16—Methods of underground mining; Layouts therefor
- E21C41/22—Methods of underground mining; Layouts therefor for ores, e.g. mining placers
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- Engineering & Computer Science (AREA)
- Life Sciences & Earth Sciences (AREA)
- Geochemistry & Mineralogy (AREA)
- Geology (AREA)
- Mining & Mineral Resources (AREA)
- Environmental & Geological Engineering (AREA)
- Remote Sensing (AREA)
- General Life Sciences & Earth Sciences (AREA)
- Drilling And Exploitation, And Mining Machines And Methods (AREA)
- Excavating Of Shafts Or Tunnels (AREA)
- Manufacture And Refinement Of Metals (AREA)
Abstract
The present invention relates to a Raise Caving mining method for mining ore from an ore body comprising developing at least two slots (3a, 3b) in a rock mass and leaving a pillar (9a) of rock mass to separate adjacent slots (3a, 3b) in order to create a favourable stress environment in the rock mass to provide protection for mining infrastructure, developing at least one production raise (6a) within the rock mass providing the favourable stress environment, mining by progressing upwards at least one production stope (13a) from the at least one production raise (6a), and drawing ore from the production stope (13a).
Description
TITLE Mining method for mining ore from an ore body TECHNICAL FIELD The present invention relates to a method for mining ore from an ore body according to claim 1.BACKGROUND ln a massive deposit, caving methods rely on naturally or induced rock mass failure either by means ofgravity, prevailing stresses, or a combination of both. Caving causes overlying material to fall into a stope. ln prior art caving methods, such as block caving and variations thereof, the ore body is undercutthereby initiating caving of ore body, whereas in sublevel caving ore bodies too competent for caving have to be mined by means of drilling and blasting. ln all caving methods hangingwall rock mass is allowed to cave as mining advances with cave initiationand continuous propagation being easier to achieve in weak rock masses and/or low primary stressconditions. ln addition, in cave mines, which are operated at relatively shallow depths, the stress magnitudes around active infrastructure can be handled.
Nevertheless, starting in late 1990s cave mining progressed to greater depths and more competentrock masses. As the stress magnitudes increase, caving is more difficult to realize and more rockpressure related issues are faced. Problems experienced comprise amongst other difficulties in caveinitiation, ensuring continuous cave propagation, production level instability during undercutting,production or mining induced seismicity and associated rock burst damage. ln a worst-case scenario, these issues could result in major economic losses or unplanned termination of the operation.
Furthermore, rock mechanical models and mining experience show that extreme abutment stressesdevelop around an undercut in block caving and variants thereof before and after initiation ofcontinuous caving, and around active sublevels in sublevel caving. The high abutment stressmagnitudes are critical and could damage undercut and production infrastructure, adversely affectrock mass properties in the future production level, or trigger damaging seismic events. Prior artapproaches against abutment stresses are for example certain undercutting strategies minimizing pre-developed infrastructure in abutments or pre-conditioning methods for reducing abutment stress magnitudes. However, the trend to caving of more competent rock masses calls for larger undercut 2areas, but this again results in higher abutment stress magnitudes and higher seismic energy release.The issues mentioned above jeopardize the application of prior art caving methods at greater depths.ln prior art caving methods, the high stresses and mining induced seismicity at great depths are a constant safety, production, and economic risk.
SUMMARY OF THE INVENTIONln view of prior art mining methods, it would be desirable to achieve a mining method for mining ore from an ore body, which so|ves or a||eviates some of the drawbacks of the prior art.
Therefore, one object of the invention is to provide a method for mining ore from an ore body whichaddresses critical rock mechanical issues and provides safety and protection for mining infrastructure when cave mining in deep, massive ore bodies.
Another object of the invention is to provide a method for mining ore from an ore body which enables large scale, low cost cave mining in deep, massive ore bodies.
The objects are achieved by a Raise Caving mining method for mining of ore from an ore bodyaccording to the independent claim, wherein further embodiments are incorporated in the dependent claims.
According the present invention, a Raise Caving mining method for mining ore from an ore body is provided which comprises the steps: Developing at least two slots in a rock mass and leaving a pillar of rock mass to separate adjacent slotsin order to create a favourable stress environment in the rock mass to provide protection for mining infrastructure, developing at least one production raise within the rock mass providing the favourable stress environment, progressing upwards by mining at least one production stope from the at least one production raise, and drawing ore from the production stope.
The mining method according to the present invention, herein also referred to as Raise Caving miningmethod, enables large scale, efficient cave mining in massive ore bodies at great depths due toprovision of favourable stress environment, where the problems related to rock mechanics arereduced, such that the overall rock pressure situation can be managed. Consequently, less extensive and expensive support is required, rock burst and associated safety risk is reduced significantly, and 3overall economic risk is lower. Moreover, the Raise Caving mining method may also be implemented at shallow depths. ln order to address critical rock mechanical issues in prior art caving methods, the present inventionrelies on de-stressing of rock mass with minimum amount of infrastructure by application of de-stressing slots and pillars, placing of production infrastructure in the rock mass that provides afavourable stress environment, and extracting of ore from the ore body located in that rock mass.Furthermore, by means of applying an advantageous mining sequence the favourable stress environment can be provided in the active mining area.
The inventors of the present invention conducted a study aiming to investigate the applicationpotential of Raise Caving from a rock mechanics point of view and to outline effects on safety,productivity and potential for automation. Study results yield that the present invention, the RaiseCaving mining method, is applicable from a rock mechanics point of view and that Raise Caving miningmethod seems to offer considerable advantages compared to existing caving methods. The followinggeneral improvements offered by the novel Raise Caving mining method are outlined. The outline isvalid for all prior art caving methods. However, specific emphasis is put on sublevel caving, which hasbeen the main mining method used in the mining company throughout the years. However, there arealso inherent problems in sublevel caving, which will be addressed by the novel Raise Caving mining method.
Each slot generates a stress-shadow at certain locations adjacent to the slot. Said stress-shadow de-stresses the rock mass thereby creating the favourable stress environment in the vicinity of the slot.The stress-shadow also extends in the vicinity of the slots, both in the vertical and the horizontaldirection, but the size and distribution of the stress-shadow may vary. Depending on prevailing orebody shapes, stress situation etc. the stress-shadow may have a varying size and shape, and may alsovary over time, depending on mining layout and sequence. ln this specification, the slots are also referred to as a de-stressing slots, emphasizing their purpose.
Therefore, it is advantageous to arrange and develop the production infrastructure in the de-stressedrock mass near the slots to ensure that the production infrastructure is protected. Thus, saidproduction raise is preferably developed in the favourable stress environment created at certain locations adjacent said slots.
According to the method at least two slots are developed in the rock mass, a pillar which is part of therock mass is left to separate the slots. Leaving a pillar between the slots generates a favourable stress environment for the further development of the said two slots in vertical direction and for the further 4development of the following slots located at a distance in the horizontal direction. The pillar controlsstress magnitude in the rock mass at the position in the rock mass where the next slot will subsequentlybe developed, thereby creating a favourable stress environment to enable development of the next following slot. ln one form of the invention, the method comprises a step of implementing a mining sequence forproviding the favourable stress environment in an active mining area. The mining sequence is a means for controlling mining induced seismicity in the active mining area. ln another form of the invention, the method comprises a step of implementing a mining layout forproviding the favourable stress environment in an active mining area. The mining layout is a means for controlling mining induced seismicity in the active mining area. ln one form of the invention the method comprises a step of developing at least one slot raise from adrift arranged on a slot access level upwards to a drift arranged above the slot access level in the rockmass. Preferably the slot raise is developed at a distance from previous developed slot or slots or at adistance from previous developed slot raise or slot raises. The distance is determined by circumstancessuch as ore body shape, rock mass conditions, stress magnitudes and mining directions. Preferably the slot raise is developed by well-known processes and equipment. ln one form of the invention, the method comprises that at least one of said slots is developed fromsaid at least one slot raise by blasting upwards from the drift arranged on the slot access level to the drift arranged above the slot access level. ln one form of the invention, the method comprises that at least one of said slots is arranged in acontact area between the ore body and the surrounding rock mass formations. However, in anotherform of the invention, the method comprises that at least one of said slots is arranged inside the orebody. Thus, a part of the ore body is located between the slot and the surrounding rock massformation. ln yet another form of the invention, the method comprises that at least one of said slotsis arranged outside the ore body. Thus, the positioning of the slots depends on ore body shape, rock mass conditions, stress magnitudes, and mining directions. ln one form of the invention, the method comprises that at least one of said slots is oriented in verticaldirection. ln another form of the invention at least one of said slots is oriented in inclined direction.However, the slot does not have to be oriented in the dip direction of the ore body. Thus, thelongitudinal axis of the slot may be oriented in vertical or inclined direction. By inclined is meant that the slot is directed at least 40 degrees from the horizontal plane. The orientation of the slots depends 5for example on the geometry of the ore body. Thus, in one form of the invention, the method comprises that adjacent slots are oriented in different directions. ln one form ofthe invention, the method comprises a de-stressing phase for generating and expandingthe favourable stress environment in the rock mass, to protect mining infrastructure, in particular theproduction infrastructure in the production area, and a production phase for extraction of ore fromthe ore body, and wherein the de-stressing phase and the production phase are integrated such that in a certain mining area the production phase benefits from the de-stressing phase.
Although both phases have different purposes, they cannot be individual, independent phases. Ratherboth phases must be designed together to form a functionally integrated and applicable Raise Cavingmining method. The two phases require different type of infrastructure. Infrastructure required forthe de-stressing phase is herein referred to as de-stressing infrastructure. Infrastructure required forstoping is herein referred to as production infrastructure. The amount of infrastructure fordevelopment of slots in the de-stressing phase can be kept to a minimum, which is advantageous inthat costs can be reduced. Moreover, this implies also that less de-stressing infrastructure is exposedto high stresses and associated costs for rock support and possible rehabilitation. The mining infrastructure comprises both de-stressing infrastructure and production infrastructure. ln one form of the invention the method comprises a step of developing at least one start-slot fromthe slot access level to a predetermined vertical extent to generate a stress-shadow to provideprotection for production infrastructure located above the slot access level and adjacent to the start- slot. ln one form of the invention the method comprises that the start-slot is developed from at least oneslot raise by blasting upwards along the slot raise from the drift arranged on the slot access level tothe predetermined vertical extent. lt is advantageous to develop the start-slot from a slot raise, sincethe machinery and equipment for developing the start-slot can be located in the slot raise and operated from there. ln one form of the invention the method comprises a step of developing a continuous start-slot fromat least two start-slots in order to generate a stress-shadow S to provide protection for productioninfrastructure located above the slot access level and adjacent to the start-slot. The continuous start-slot is formed by joining at least two adjacently arranged start-slots to a continuous start-slot. This isadvantageous in that the continuous start-slot generates a stress-shadow which provides protectionfor production infrastructure such as drawpoints, arranged adjacent the start-slots. Furthermore, the infrastructure on a draw level may be protected from exposure to high stress by the continuous start- 6slot. The vertical extent of the start-slot depends on for example rock mechanics and rock massconditions, but the vertical extent is adapted such that the area of infrastructure on the draw level is appropriately and sufficiently de-stressed. ln one form of the invention the method comprises a step of developing at least one of the slots fromthe roof of at least one start-slot to the raise level arranged above the slot access level, wherein theroof area of the slot is smaller than the roof area of the start-slot. Thus, the slot is developed as acontinuation of the start-slot. ln particular, the cross-sectional area perpendicular to the longitudinalaxis of the slot is smaller than the cross-sectional area of the start-slot perpendicular to its longitudinal axis. Preferably, the start-slot and the slot are configured to have similar thickness. ln one form of the invention, the method comprises a step of developing a slot access level in the rockmass. The slot access level, arranged below the draw level, is the level where the slots/ start-slotsbegin. The slot access level may also be provided with slot drawpoints and drifts for drawing swellduring start-slot and slot development. A drawpoint is the excavated structure, through which the caved or broken ore is loaded and removed from the start-slot, slot or stope. ln one form of the invention, the method comprises a step of developing the draw level located in afavourable stress environment. Typically, the draw level is developed in the rock mass above the slotaccess level. Preferably production infrastructure is developed at the draw level and in a stress-shadow provided by at least one of said slots and / or at least one of said start-slots. ln one form of the invention, the method comprises developing at least one further draw level locatedin a favourable stress environment. Several draw levels may be provided to enable efficient drawingof ore from the stopes. ln one form of the invention, the method comprises that the draw level comprises draw infrastructure such as slot drawpoints, stope drawpoints, drifts. ln one form of the invention the drawpoints may be long-term and stationary. This is advantageous in that automation in mining is facilitated. ln one form of the invention, the method comprises a step of developing slot drawpoints into the slotsand/or start-slots at the draw level. The draw of broken rock mass in slots and start-slots can either bedone from the slot access level, the draw level or for example raise levels arranged above the slot access level.
After slot development has de-stressed the region of the rock mass where the draw level is arranged,slot drawpoints may be installed at the main draw level. Thereafter the slot access level is no longer required and may be abandoned. 7ln one form of the invention, the method comprises that the production stope generates a favourablestress environment which protects production infrastructure in the vicinity of the production stope.This is advantageous in that further production infrastructure such as drifts, raises, drawpoints, or rock passes can be safely installed next to the production stope in a favourable stress environment.
During the production process of the mining operation several production stopes may be developednext to each other. ln one form of the invention, the method comprises that the interaction of two ormore production stopes generates a regional favourable stress environment for protection of mininginfrastructure. Preferably, the progressing production process results in an increasing extent of theregional favourable stress environment in the rock mass such that the mining infrastructure can bestepwise developed according to production progress and the mining infrastructure can benefit from the regional favourable stress environment. ln one form of the invention, the method comprises a step of developing an intermediate draw levelwhere required, to improve extraction of ore from the stope. lf the ore flow to the draw level cannotbe ensured due to ore body shape or ore body inclination, the development of one or moreintermediate draw levels may become necessary. The intermediate draw levels may be developed on the raise levels. ln one form of the invention, the method comprises a step of developing stope drawpoints into theproduction stopes from one or more intermediate draw levels after a production stope roof hasadvanced beyond the intermediate draw level. This is advantageous in that ore from the production stope may be drawn on several levels. ln one form of the invention, the method comprises a step of delayed development of at least onerock pass where required, in between an intermediate draw level and another level below the saidintermediate draw level. Preferably the rock pass is developed in favourable stress environmentcreated by at least one production stope. By delayed development is meant that the rock pass is developed after a production stope roof has advanced beyond the said intermediate draw level. ln one form of the invention, the method comprises a step of delayed development of at least onehorizontal or inclined haulage tunnel where required. The inclined haulage tunnel extends between anintermediate draw level and another level below or above the intermediate draw level. The inclinedhaulage tunnel may be located in favourable stress environment created by at least one production stope. 8ln one form of the invention, the method comprises a step of mining the production stope by drillingand blasting. ln another form of the invention the method comprises a step of mining the production stope by caving. ln one form of the invention, the method comprises a step of developing at least one slot from a driftarranged on a first sublevel by means of drilling and blasting rounds in a retreat manner upwards to a drift arranged on a second sublevel arranged above the first sublevel in the rock mass. ln one form of the invention, the method comprises a step of extracting a pillar. Preferably said pillaris extracted by weakening the pillar actively by drilling and blasting from at least one production raise.Alternatively, said pillar is extracted by degrading the pillar strength by decreasing the pillar width-to-height ratio due to nearby stope mining and facilitating pillar yielding and self-destruction. Moreover, the pillar may de-stress because of pillar yielding and self-destruction. ln one form of the invention, the method comprises a step of extracting a de-stressed pillar by arranging a production raise in or near the de-stressed pillar. ln one form of the invention, the method comprises a step of extracting a pillar by means of caving. ln one form of the invention, the method comprises a step of extracting a pillar by means of drilling and blasting. ln one form of the invention, the method comprises a step of preventing premature caving ofhangingwall due to presence of broken rock mass in the slots and stopes, pillars and implementing draw strategies. ln one form of the invention, the method comprises a step of connecting at least one production stope to previously caved masses thereby allowing previously caved masses to fill up the production stope. ln one form of the invention, the method comprises a step of caving parts of the hangingwall, to fill up at least a part of at least one mined out production stope. ln one form of the invention, the method comprises a step of caving the hangingwall facilitated by extraction of pillars thereby removing the hangingwall support provided by the pillars. ln one form of the invention, the method comprises a step of caving of the ore body between the overhand side of the slot wall and the hangingwall, wherein caving is caused by extraction of the pillars. ln one form of the invention, the method comprises a step of developing a slot from a raise, where the raise is not located inside the slot. This is advantageous for example in case a slot is blocked, whereby 9a raise located outside the blocked slot can be used for drilling and blasting inside the slot in order to clear the said blockage. ln one form of the invention, the method comprises a step of implementing at least one slot for de- stressing rock mass and protecting critical infrastructure in another mining method. ln one form of the invention, the method comprises that the mining geometry is adapted to and determined by production and/or ore body geometry. ln one form of the invention, the method comprises that the mining sequence is adapted to anddetermined by production and/or ore body geometry and/or rock mechanics consideration thereby controlling mining induced seismicity and high stresses. ln one form of the invention, the method comprises that the mine layout, infrastructure position and mining sequence can be adapted on short notice. ln one form ofthe invention, the method comprises that the mining sequence comprises developmentof the slot ahead of development of the respective production stope where the roof of the slot is apredetermined vertical distance ahead of the roof of the production stope, to ensure that the production stope is mined in rock mass located within favourable stress environment.
Preferably the stoping commences when the favourable stress environment has been generated. Thus, the development of a part of the slot should be made prior to developing the corresponding stope. ln one form of the invention the method comprises a step of monitoring the production stope via theproduction raise. Such monitoring may be performed by monitoring means arranged inside the production raise. ln one form of the invention the method comprises a step of monitoring the slot and/ or start-slot via the slot raise. Such monitoring may be performed by monitoring means arranged inside the slot raise. ln one form of the invention the method comprises a step of controlling risk of air blast and cave stallin the production stope via the production raise. Such controlling may be performed by controlling means arranged inside the production raise. ln one form of the invention, the method comprises repeating the steps of the method to a larger area in the rock mass, to exploit the ore body in a safe manner. ln one form of the invention the method comprises a step of backfilling parts of the production stope. ln one form of the invention the method comprises the production of backfill material by miningdesignated excavations in waste rock. This could be achieved either by increasing a stope in verticalextent or producing separate stopes with the only purpose to produce waste for backfill to e.g. reduce surface deformations. ln one form of the invention, the method comprises a step of continuation of development of at leastone of the previously developed slot raises upwards in the rock mass from the current level to a further level located higher up in the rock mass. ln one form of the invention, the method comprises a step of continuation of development of at leastone of the previously developed slots by blasting upwards from the slot raise towards a further level located higher up in the rock mass. ln one form of the invention, the method comprises a step of continuation of developing at least one of said production raises upwards towards a further level in the de-stressed rock mass. ln one form of the invention, the method comprises a step of continuation of mining at least one ofthe production stopes upwards from the production raise towards a further level and drawing ore from the production stope via the draw level and/or an intermediate level. ln one form of the invention, the method comprises a step of leaving a temporary pillar arranged in between the production stope and the slot that is located adjacent the production stope. ln another form of the invention, the method comprises a step of leaving a temporary pillar in between adjacent production stopes.
Furthermore, certain elements of Raise Caving mining method could be applied in other ways. Forexample, de-stressing slots developed by raises could be applied as a de-stressing element in existingmining methods or for de-stressing and protection of critical long-term infrastructure. Moreover,neighboring stopes mined by raises could also replace a traditional undercut in block and panel caving.ln this case, the size of the stope roof would be increased, until caving is initiated. Thus, raises equippedwith appropriate machinery above an active cave would provide possibilities for pre-conditioning, cave advance monitoring, facilitating cave advance and steering of caving front. ln summary, the Raise Caving mining method according to the invention may preferably be realized in a rock mass with an ore body which is massive and located at shallow depth or great depth. lt should be noted that great depths refer to depths where the ratio of primary rock stress to uniaxial compressive strength (UCS) exceeds 0.4. Massive ore bodies are large in all directions and may be of 11any shape or size, also thick tabular shaped ore bodies are considered massive. As the ore body shapemay vary, the main draw level, the raise levels, the slot access level and the intermediate draw level may be situated on different depths. ln prior art caving methods, seismicity occurs often near active infrastructure causing considerabledamage. ln contrast to prior art caving methods, only a very small amount of active infrastructure isrequired in seismically active areas when using the Raise Caving mining method according to theinvention. The method is thus advantageous in that seismic energy may be released distant from mostof the active infrastructure, i.e. drifts, drawpoints, raises, ore and rock passes, shafts etc. of varioussize and geometry, which are necessary to gain access to the ore body and to prepare the ore body for extraction. ln particular, prior art sublevel caving is known for long lead times of developments of sublevels. Suchdevelopment is associated with high upfront capital cost. ln addition, the built infrastructure is alsovulnerable to stress and rock burst damage prior to its actual use. Moreover, there is limitedknowledge regarding prevailing and rock mass conditions at the time of development. ln contrastthereto, the Raise Caving mining method according to the invention requires only a very small amountof infrastructure being developed upfront. Thus, most of the infrastructure is created just-in-timereducing upfront capital cost drastically and decreasing exposure time to high stress conditions.Additionally, short-term changes in the mine layout to react on encountered conditions are easilyimplementable. For example, placing infrastructure in difficult ground conditions can be avoided,designing of specific mine layouts and mining sequences in critical areas is possible or blasting work can be adapted to local conditions easily.
Thus, the Raise Caving mining method according to the invention is particularly advantageous in thatit allows for adaptions in mine layout and/or mining sequence. Thereby, it is possible to improve thecontrol of seismicity and/or high stresses and/or to improve infrastructure stability. ln addition, such adaptions may further be implemented on short notice as well. ln prior art sublevel caving, conditions and excavation geometries of workplaces are very variable.Workplaces and activities are spread over numerous sublevels. For this reason, only a limited degreeof automation could be realized so far in key processes related to development, rock breaking and mucking. ln contrast, the Raise Caving mining method requires significantly less development on a few levelsonly. Moreover, geometries of raises are very well defined and repetitively used throughout.
Accordingly, currently faced issues in automation, such as positioning of machinery or drill hole 12detection, can be overcome. Additionally, drawpoints in Raise Caving are long-term and stationary.
Subsequently, a Raise Caving operation is comparable to an "underground rock factory”.
The Raise caving mining method according to the present invention is advantageous in that it offers significant automation potential in the actual stoping process.
Furthermore, in prior art sublevel caving numerous closely spaced drawpoints are required on everysublevel. Comparatively, only a small amount of ore can be recovered from each drawpoint, beforethe drawpoint must be closed and the next one must be opened. The lifetime of a drawpoint is typicallyin the range of days. Production blasting takes place at the position of drawpoints as well, possiblycausing drawpoint damage. Moreover, these drawpoints and associated infrastructure are always situated below the mined-out area in a stressed and seismically active zone. ln contrast to sublevel caving, in the Raise Caving mining method according to the invention developeddrawpoints are used over many month or years. Furthermore, blasting and/ or cave initiation isrealized using production raises. Every production raise and associated de-stressing infrastructureutilize large deposit volumes. As a result, the required infrastructure amount may be reduced by 50%or even more compared to prior art sublevel caving. Accordingly, the required number of machineryand the required amount of consumables, such as explosives, rock support or energy, are reducedsignificantly. Subsequently inherent nitrogen losses from drift development blasting are reducedsubstantially. Additionally, drawpoints and production infrastructure are arranged in de-stressed rock maSS.
Consequently, the Raise Caving mining method according to the present invention decreasesinfrastructure development efforts considerably and enables the majority of infrastructure to be situated in de-stressed areas.
Furthermore, in prior art sublevel caving every blast ring acts independently. The fragmentation andgravity flow are heavily influenced by the initial blast conditions (blast confinement, chargeability, drilldeviation etc.). Hence, there are also great variations in the performance expressed in extraction figures, such as dilution, recovery and the occurrence of hang-ups. ln contrast to sublevel caving, in the Raise Caving mining method a free-face blasting situation prevails.Accordingly, a lower specific charge concentration can be used. Substantial secondary fragmentationeffects can be expected, as the material falls into the stope and draw columns are high. Based upon the improved fragmentation, the probability of hang-ups is also reduced greatly. 13Therefore, the Raise Caving mining method according to the invention may furthermore enable improved fragmentation and reduce hang-up occurrence.
Moreover, in prior art sublevel caving, draw of ore takes place at many drawpoints, which are inoperation over a rather short period and thus only a comparably small tonnage of ore is drawn fromeach drawpoint. The actual dilution mechanisms depend on various factors, such as compaction of cave masses, fragmentation, and porosity of the blasted sublevel caving ring.
However, in contrast to sublevel caving, in the present Raise Caving mining method, the high ore column protects against dilution, if good draw control practice is followed.
Thus, the Raise Caving mining method according to the present invention is advantageous in that improved controlling of dilution may be achieved.
Furthermore, in sublevel caving, hangingwall caving and associated surface subsidence areas (thelowering of the ground surface following underground mining) increase gradually with every minedsublevel, but the situation is different when using the Raise Caving mining method. When the miningmethod according to the present invention is applied mining commences from bottom to top andhangingwall caving is delayed due to presence of broken rock mass in the slots and stopes, pillars andapplied draw strategies. Consequently, surface subsidence may occur at a later stage and the footprint may be smaller. Thus, the impact on environment may be reduced.
Therefore, another advantage with the Raise Caving mining method according to the present invention is that the footprint of surface deformations may be reduced.
Above outlined technical advantages achieved by the Raise Caving mining method according to thepresent invention may result in some or all of the following overall improvements compared to prior art caving methods. 0 Improving safety:~/ fewer workplaces, which need to be secured~/ high degree of automation~/ less infrastructure in highly stressed and seismically active rock mass~/ reduced exposure of mine workers to high rock stresses and thus less exposure to hazardous areas \ standardized workplaces and procedures (underground rock factory) \ accessibility of stope (reduced risk for air blast, cave stall etc.) 14 0 reducing mining costs significantly: ~/ high degree of automationprovides better fragmentation and less hang-upsrequires markedly lower infrastructure development by about 50%does not need large upfront infrastructure developmentallows for faster ramp-up timeallows to place majority of infrastructure in de-stressed rock masslower support and rehabilitation demanddelays and reduces needs for surface infrastructure relocation (if necessary) allows to increase production capacity due to less dilution \\\\\\\\\ more predictable and stable production 0 providing better sustainability of the mining operation: ~/ enables resource utilization at great depthscauses reduced consumable consumption and nitrogen lossesenables use of stationary, power line supported equipmentenables use of electrified equipment requires smaller waste dumps due to less dilution \\\\\ smaller surface subsidence footprint ln 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 minedat 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. ln this specification the term "deposit" is used synonymously for ore body.
"Hangingwall" is the term which describes the upper or overhanging wall of a deposit, ore body,excavation, stope, an inclined vein, fault, or other structure. The term "hangingwall stability" is usedprimarily to describe the rock conditions of the upper and overhanging walls of excavations from astability point of view. ln open stopes stable hangingwalls are required. ln caving stopes the hangingwalls should fail. The critical parameters which determine hangingwall conditions are the strength and structure of the hangingwall rock mass and the dimensions and shape of the excavation.
The expression "hangingwall caving" refers to progressive failure or caving of hangingwall rocks.
The term "underhand" refers to a part of the rock mass facing the footwall, and the term "overhand" refers to the part of the rock mass facing the hangingwall.
The term ”slot” refers to a long tabular excavation with length and width which are several timesgreater than its height. The extension of the slot along its length is referred to as long axis and can behorizontal, vertical or inclined. The slot is a discontinuity in the rock mass which cannot transmitstresses acting normal on the slot surfaces. As a result, the volume of rock in the vicinity of the slot isde-stressed in the direction normal to the slot surface. The de-stressing effect in the rock massdiminishes with distance from the slot. De-stressing is greatest in the volume of rock behind the slot area defined by the length and width of the slot.
Furthermore, a ”pillar” is that part of the rock mass left unmined to prevent rock displacementbetween opposing rock walls in an excavation. Horizontal pillars are known as sill pillars. Other pillarsare named after their function, which could be either to support the excavations (support pillars) or toprotect other mine infrastructure (protection pillars). Depending on the characteristics one candistinguish between a barrier pillar, a yielding pillar or a crush pillar. Thus, a "barrier pillar" refers to alarge, massive pillar being able to withstand considerable loads", a "yielding pillar" refers to a pillarwhich is designed to deform constantly under a certain load, and a ”crush pillar" refers to a pillar which is designed to fail stable and reliably at a certain load.
The expression "favourable stress environment” refers to a stress state, which is controllable, andwhich does not require extensive and expensive support measures for subsequent operation in therespective mining area. A favourable stress environment could be either a de-stressed area in a rockmass, or an abutment area where abutment stresses are limited or restricted to a controllablemagnitude. The favourable stress environment serves the purpose to create a favourable environmentfor the subsequently establishment of slot raises and slots in the mining area. lt further facilitates theestablishment of the production raise and the subsequent operation in the production stopes. Thecombination of the de-stressing slots and the production stopes create a favourable environment for the infrastructure in the vicinity of the production area.
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. 16The term "stress-shadow" refers to a part of the rock mass where the stress is reduced in at least onedirection 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 vertical or inc|ined mine infrastructure opening.
The term ”rock pass” refers to steeply inc|ined passage-ways used for the transfer of material inunderground mine workings. Rock passes are designed to utilize the gravitation potential betweenlevels in order to minimize haulage distances and facilitate a more convenient material handlingsystem. The term "ore pass" refers to rock passes that are solely used for the transport of ore. ln deepmines it is common practice to gravitate the ore to the deepest level in the mine from where it ishoisted to surface. The terms ”tunnel” and ”drift” are herein used as synonyms and refer to same type of infrastructure.
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 and/or caving, and extracting rock or mineral in stopes, subsequent to development.
”Active mining areas” are areas of significant and ongoing stress changes resulting from miningactivities. These are predominately but not exclusively the extraction (stoping) areas. The heading oftunnels under development are also active areas but on a localized scale. Active mining areas requireongoing supervision, monitoring of ground conditions and attention to excavation support. As miningadvances active areas change to passive areas which require reduced levels of supervision and monitoring with the exception of main transport and regularly used infrastructure excavations.
The expression "mining sequence" refers to the sequence of mining activities which should be followedin order to achieve the overall goals of extraction of the ore body as complete as possible, the safetyand economy of the mining operation, considering I factors, rock mechanical constraints and other factors.
The expression "drawpoint" refers to the excavated structure, through which the caved or broken ore is loaded and removed from the slot or stope.
The term "de-stressing infrastructure” refers to the infrastructure required in the de-stressing phase.
The de-stressing infrastructure comprises amongst other tunnels, inclines and/ or declines to slots 17 and/or start-slots, slot raises or slot drawpoints. The de-stressing infrastructure is situated on several levels, for example on raise levels or main draw level.
The term ”production infrastructure” refers to the infrastructure required for the extraction of the orebody during the production phase. The production infrastructure comprises amongst others drawlevels, stope drawpoints, tunnels, cross-cuts, production raises, ore passes and/or rock passes. Theproduction infrastructure may be situated on several levels, for example draw level or intermediate draw levels.
The term "mining infrastructure” comprises both de-stressing infrastructure and productioninfrastructure. The term ”main infrastructure” refers to the long-term infrastructure, which is requiredthroughout the life of mine for the purpose of gaining access to the ore body. The main infrastructurecomprises amongst others main shafts, main ramps, service excavations, main transportation tunnels from extraction area to main shafts or main ramps or ventilation raises.
III ln this specification the term ”slot access leve should be understood as a level in the rock mass whichis suitable to function as a starting level for developing start-slots and/or slots in the Raise Caving mining method.
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 which is required to cave.
Furthermore, in specification the expressions ”develop” and ”developing” should be considered asbroad terms and the term ”develop” should have the same meaning as the words provide/arrange, and the word ”developing” should have the same meaning as the words providing/arranging.
Additional objects, advantages and novel features of the present invention will become apparent toone skilled in the art from the following details and through exercising the invention. Whereasexamples of the invention are described below, it should be noted that the invention may not be restricted to the specific details described.BRIEF DESCRIPTION OF DRAWINGS ln order to fully understand the present invention and further objects and advantages of it, the detaileddescription set out below should be read together with the accompanying drawings, in which the same references denote similar in the various figures, and in which: 18 Figure 1(a)-(c) schematically illustrates the basic principle of stope development according to the invention.
Figure 1(a) illustrates a platform lowered into a raise for drilling and charging activities, Figure 1(b) illustrates the platform stored at top in hoist frame for blasting, Figure 1(c) illustrates excavation after blasting with void filled due to swell.
Figure 2 schematically illustrates one form of the Raise Caving method according to the inventionshowing a view of a horizontal cross-section of slots and associated stress environment developed in rock mass.
Figure 3 schematically illustrates one form of the Raise Caving method according to the inventionshowing a view of a horizontal cross-section of slots, pillars and production stopes and associated stress environment developed in rock mass.
Figure 4a schematically illustrates an isometric view of one example of a tabular slot and a corresponding slot raise according to the invention.
Figure 4b schematically illustrates an isometric view of one example two tabular slots, corresponding slot raises and a pillar separating the slots according to the invention.
Figure 4c schematically illustrates an isometric view of one example of a de-stressing layout according to the invention wherein the tabular slots are vertical and oriented in the same direction.
Figure 4d schematically illustrates an isometric view of one example according to the invention wherein the de-stressing layout is such that tabular slots are inclined.
Figure 4e schematically illustrates an isometric view of one example according to the invention wherein the slots 401,402,403 are vertical and oriented in a different direction.
Figure 4f schematically illustrates an isometric view of one example according to the invention wherein each of the slots is inclined and oriented in a different direction.
Figure 4g schematically illustrates an isometric view of one example of a slot according to the invention wherein the slot is gradually changed in upwards direction.
Figure 4h schematically illustrates a horizontal cross-section of one example of slots according to the invention wherein the slots are located inside the ore body. 19Figure 4i schematically illustrates a horizontal cross-section of one example of slots according to the invention wherein the slots are located outside the ore body but inside the hangingwall.
Figure 4j schematically illustrates a view of a horizontal cross-section of one example of slots accordingto the invention wherein the slots are located partially inside the ore body and partially inside the hangingwall.
Figure 4k schematically illustrates a view of a vertical cross-section of one form of the Raise Caving method according to the invention.
Figure 4l schematically illustrates a horizontal cross-section of one form of the Raise Caving mining method according to the invention.
Figures 5a schematically illustrate one example of de-stressing slots according to the invention.
Figures 5b schematically illustrate another example of de-stressing slots according to the invention.
Figures 5c schematically illustrate one example of de-stressing slots according to the invention.
Figure 6a schematically illustrates a view of one form of the method according to invention.
Figure 6b schematically illustrates a line drawing of a further development of the form of the method as shown in Figure 6a; Figure 7a schematically illustrates a vertical cross-section of a lower part of the slot 3a and start-slot 4a illustrated in Figure 6a; Figure 7b schematically illustrates a side view of the form of the method shown in Figure 6b; Figure 8a schematically illustrates a view of another one form of the method according to inventionshowing further progress of de-stressing of the rock mass and initial preparation of the production phase.
Figure 8b schematically illustrates a line drawing of the form of the method as shown in Figure 8a.
Figure 9a schematically illustrates vertical cross-section a lower part of the slot 3a and the start-slot 4a illustrated in Figure 8b; Figure 9b schematically illustrates a vertical cross-section of slot 3a shown in Figure 9a.
Figure 10a schematically illustrates a view of steps of one form of the Raise Caving mining method according to the invention.
Figure l0b schematically illustrates a line drawing of a further development of the form of the Raise Caving mining method according to the invention as shown in Figure l0a.
Figure lla schematically illustrates a lower part of a vertical side view through stope l3a of the form of the Raise Caving mining method illustrated in Figure l0a.
Figure llb schematically illustrates a lower part of a side view of stope l3a of the view as illustrated in Figure l0b.
DETAILED DESCRIPTION OF FORMS AND EXAMPLES OF THE INVENTION The Raise Caving mining method, the mine layout and the mining sequence will be described in the following with references to the figures.
Raises are the central element in the Raise Caving mining method according to the invention. The raisesare used for development of production stopes and for extraction of ore in stopes in de-stressed rockmass. The raises are developed by means of conventional techniques. Preferably, raises are also usedfor development of the slots. However, the slots may also be developed by conventional techniques, such as drilling and blasting a slot from horizontal tunnels.
Figure la, lb and lc illustrate in a vertical cross-section the basic principle of stope development andstope blasting from a raise with mining equipment located in the raise. Figure la illustratesschematically the development of a stope 100 by drilling and blasting carried out from the miningequipment positioned on a platform 102, which is moved with a shaft hoist system 104 inside a raise 106.The same method may also be used when developing a slot.
As shown in Figure la, a raise 106 has already been developed by conventional techniques. Theplatform 102 and hoist system 104 are installed after development of the raise 106 is finished. Thestope l00 is blasted in subsequent slices in upwards direction. However, in another form of theinvention, the stope may also be run in a caving mode. Thereby, the rock mass above the roof of thestope fractures due to prevailing stresses and forces and thus rock mass detaches from the stope roof and falls into the stope.
Figures la and lb illustrate schematically blast holes 107 drilled at a distance to the existing stope roof.The blast holes 107 could be either horizontal as shown in Figure la and lb or inclined to achieve abetter toe breakage. After blast holes 107 are drilled and charged with explosives, the hoist platform102 is retracted to the top and stored in a safe position so that damage to the platform 102 resulting from blasting is avoided. 21Figure lc illustrates schematically that blasted rock mass 108 falls into the stope 100, and that theremust be enough free space to absorb the swell of fragmented rock resulting from blasting. Before thenext blast ho|es can be fired, enough blasted rock mass must be drawn from the stope accordingly.
However, only the swell is drawn out of the stope so that the formation of an air gap is avoided.
However, if the stope is run in caving mode, the caving rate determines the draw rate. Namely, thedraw rate must not exceed the rate of caving. However, even in caving mode the stope can be accessedvia the raise 106, so that the cave back and the muck can be monitored. Moreover, the raise 106 andinstalled machinery on the platform 102 can be used for conducting pre-conditioning and pre-breaking techniques.
Routine work on the platform 102 inside the raise 106 can be carried out remote controlled orautomated. Repair and maintenance of machinery can be carried out at the top of the raise, when theplatform 102 is retracted. Hence, presence of mining personnel in raises can be kept to a minimumfor, e.g. routine raise inspections or special, irregularly occurring work, which cannot be done byinstalled machinery on the platform or which cannot be done by other separate machinery on theplatform run remote controlled or automated. As presence of mining personnel might be required inraise 106 and as machinery in raise must be protected from potential rock falls, the raise must be keptstable. lf rock mechanical conditions require raise support, support can be installed from the platform102. The platform construction itself provides additional protection for miners and machinery. Theraise 106 has preferably a circular cross-section, which is a smooth and simple excavation shape. Theplatform 102 can be positioned in vertical direction via the hoist system 104. The preferably circularcross-section and the vertical positioning via the hoist system enable easier drill hole detection andidentification compared to irregular drift shapes in conventional mining situations. This drill holedetection is critical for automation. Moreover, the platform 102 could have several platform levelsabove each other, where different types of machinery can be installed. These platforms shall bemodular, stackable and interchangeable for the purpose of quick insertion and changes of machinery or repair of machinery. This configuration also provides the possibility to parallelize work in the raise.
The Raise Caving mining method according to the invention relies on de-stressing of rock mass byapplication of de-stressing slots. De-stressing slots are developed with minimum amount of infrastructure, which is built in advance.
Infrastructure, in particular production infrastructure, is developed in the rock mass de-stressed by the slots such that ore body inside that rock mass can be extracted. Furthermore, by means of applying an 22advantageous mining sequence the favourable stress environment can be provided in the active mining area.
Figure 2 schematically i||ustrates a horizontal cross-section of one form of the Raise Caving miningmethod according to the invention wherein the slots 201,202 are developed progressively upwards invertical direction in rock mass 60 according to the invention and in particular the de-stressing of rockmass. The first slot 201 and the second slot 202 are separated by pillar 211, which has been left between the slots 201,202 to separate them. Slot 201 and 202 are filled with broken rock mass.
Each slot 201,202 generates a stress-shadow S at certain locations adjacent to the slot, which isillustrated with dashed lines on each side of the slot. The stress-shadow S de-stresses the rock mass, which creates a favourable stress environment.
Thus, the stress-shadow S provides a reduced stress in the rock mass in comparison with the stress,which would be prevailing without the de-stressing slot. However, the rock mass also exhibits anincreased stress T located at each end of the slot 201,202. Furthermore, the pillar 211 provides controlof the stress magnitude in the rock mass at the position where the next following slot (on the left orright side of the slots 201, 202 is developed and near slot roofs of slots 201 and 202 thereby creatinga favourable stress environment to enable development of the next slot (on the left or right side of the slots 201,202 and further development of slots 201 and 202.
The actual distribution of the stress-shadow S and the favourable stress environment depend also onthe prevailing rock mass conditions, primary stress magnitudes, directions, the mine layout and miningsequence. The stress-shadow S creates a favourable stress environment in the rock mass that providesprotection for the mining infrastructure. Infrastructure, in particular production infrastructure, isdeveloped in the rock mass, which is de-stressed by the slots such that extraction of the ore body in de-stressed rock mass is enabled.
Figure 3 schematically i||ustrates a view of a horizontal cross-section of slots 301,302,303,304, stopes351,352,353 developed progressively upwards in vertical direction in ore body 61 according to oneform of the invention and in particular the de-stressing of rock mass at a later stage, where stopes351,352,353 have already been mined. Slots 301,302,303,304 and stopes 351,352,353 are filled withbroken rock mass. Slots 301,302,303,304 and stopes 351,352,353 were developed from slot raises andproduction raises, respectively. Figure 3 shows the extent of the stress shadow S and the favourablestress environment in the rock mass created by the slots 301,302,303,304 and stopes 351,352,353 schematically. The actual distribution of the stress-shadow S and the favourable stress environment 23depend also on the prevailing rock mass conditions, primary stress magnitudes, directions, the mine layout, and mining sequence.
Figure 3 i||ustrates that as stoping progresses and the extraction of production stopes 351,352,353continues where most of the pillars 311,312 between the slots 301,302,303 are weakened andsubsequently removed. Pillar 311 has been extracted as a step ofthe Raise Caving mining method sincethe stopes 351,353 have been mined. Between the slots 302,303 are located the remains of separatingpillar 312. Pillar 312 is partly extracted on the left side 312a and partly fractured and broken on theright side 312b. Thus, the right side 312b of pillar 312 is de-stressed. Pillar 313 separates the slots 303and 304 in the ore body 61. Accordingly, pillar 313 provides control of stress magnitude near slot roofsof slots 303 and 304 thereby creating a favourable stress environment. Furthermore, pillar 313 enablesthe development of the next slot at the right side of slot 304 from slot raise 321 by controlling the stress magnitude at position of slot raise 321.
The extent of stress shadow S may vary throughout the mining process. To illustrate, the stress-shadowS is indicated as an area delimited by dashed line around the slots, pillars, and stopes. Extracting thestopes 351,352,353, extracting the pillar 311 and extracting (left side 312a) and weakening (right side312b) of pillar 312 increase the size of stress shadow S near slots 301,302,303. ln comparison, thestress shadow S near slot 304 is still significantly smaller. Accordingly, the stress shadow S iscontinuously extended throughout the mining process thereby generating a regional favourable stressenvironment. Based upon that, the production stopes also provide protection for further mininginfrastructure situated in said stress shadow S. The stress-shadow S creates a favourable stressenvironment in the rock mass, which protects mining infrastructure such as for example the slot raises,production raises, ore passes, rock passes or stope drawpoints, from high stress and mining inducedseismicity. The stepwise progression of the stoping progression and extraction of production stopesand development of further slots in Fig. 3 i||ustrates implementation of an example of a mining sequence providing the advantageous, favourable stress environment in the active mining area.
Figures 4a to 4l schematically illustrate various examples of arrangements of de-stressing slots thatmay be developed and used in the method according to the invention to achieve a favourable stressenvironment for the mining infrastructure. Figure 4a to 4l outline the flexibility and adaptability of thede-stressing slots according to rock mass environment, rock stress situation, ore body shape anddimensions and the mining sequence. Furthermore, also combinations of these examples may be used in the method according to the invention. 24Figure 4a schematically illustrates an isometric view of one example of a tabular slot 401 and acorresponding slot raise 421 according to the invention. The slot has a main, central longitudinal axisA1, and a transverse axis A2 perpendicular to the longitudinal axis. The cross-section of the slot hastwo perpendicular axis A2and A3, wherein A2 is longer than the A3, see Figure 4a. The slot may havean essentially rectangular cross-section or an elliptical cross-section. As an example, the dimensions ofthe slots shown in figure 4a is approx. 50 x 10 m in direction of their axis A2 and A3. The referencesA1, A2, A3 for the axis are used in the further description of slots. The slots may have a tabular shape or other shapes.
Figure 4b schematically illustrates an isometric view of one example of two tabular slots 401,402,corresponding slot raises 421,422 and a pillar 411 separating the slots 401,402 according to theinvention. The pillar has a main, central longitudinal axis P1, and a transverse axis P2 perpendicular tothe longitudinal axis. The cross-section of the pillar has two perpendicular axis P2 and P3, see Figure4b. As an example, the dimensions of the pillar shown in figure 4b are approx. 50 x 10 m in directionof their axis P2 and P3. The references P1, P2, P3 for the axis of a pillar are used in the furtherdescription of pillars. The extension of the pillar in direction of axis P1 is referred to as the length ofthe pillar. The extension of the pillar in direction of transverse axis P2 is referred to as width of the pillar and the extension of the pillar in direction of axis P3 is referred to as height of the pillar.
Figure 4c schematically illustrates an isometric view of one example of a de-stressing layout accordingto the invention comprising three tabular slots 401,402,403 developed from three slot raises421,422,423. The central longitudinal axis A1 of each of the slots 401,402,403 is oriented in verticaldirection and the slot raises 421,422,423 are vertical. Moreover, the axis A2 of each of the slots401,402,403 are oriented in the same direction and the longitudinal axis A1 of each of the slots 401,402,403 is in the same plane. Pillars 411,412 separate neighboring slots.
Figure 4d schematically illustrates an isometric view of another example according to the inventionwherein the de-stressing layout is such that tabular slots 401,402,403 are inclined. Thus, thelongitudinal axis A1 of slots is directed at least 40 degrees from the horizontal plane. Slots 401,402,403are developed from inclined slot raises 421,422,423 and pillars 411,412 separate neighboring slots.The axis A2 of the slots 401,402,403 is oriented in the same direction and the longitudinal axis A1 of each of the slots 401,402,403 is in the same plane.
Figure 4e schematically illustrates an isometric view of another example according to the inventionwherein the de-stressing layout comprises three tabular slots 401,402,403 oriented in vertical direction developed from vertical slot raises 421,422,423, whereby in this case the axis A2 of each of the slots 401,402,403 is oriented in a different direction. Pillars 411,412 separate neighboring slots.
Moreover, the longitudinal axis A1 of each of the slots 401,402,403 is not in the same plane.
Figure 4f schematically illustrates an isometric view of another example according to the inventionwherein the de-stressing layout comprises three tabular slots 401,402,403 oriented in inclineddirection developed from inclined slot raises 421,422,423, whereby in this case the axis A2 of each ofthe slots 401,402,403 is oriented in a different direction. Pillars 411,412 separate neighboring slots.
Moreover, the longitudinal axis A1 of each of the slots 401,402,403 is not in the same plane.
Figure 4g schematically illustrates an isometric view of another example according to the inventionwherein a slot 409 is developed from a slot raise 429. ln this example, the orientation of the axis A2 ofthe slot is gradually changed as the slot is developed in upwards direction. Thus, the slot has a "helix- type shape”.
Figure 4h schematically illustrates a horizontal cross-section of one example according to the inventionwherein slots 401,402,403 are developed progressively upwards in vertical direction. The slots401,402,403 are located inside the ore body 61. Stress shadows S and high stress zones T are alsoindicated. The figure indicates that the slots 401,402,403 are filled with broken rock mass, as described above.
Figure 4i schematically illustrates a horizontal cross-section of another example according to theinvention wherein slots 401,402,403 are developed progressively upwards in vertical direction. ln thisexample the slots 401,402,403 are located outside the ore body 61 but inside the hangingwall 62.
Stress shadows S and high stress zones T are also indicated.
Figure 4j schematically illustrates a view of a horizontal cross-section of another example according tothe invention wherein slots 401,402,403 are developed progressively upwards in vertical direction. lnthis example the slots 401,402,403 are located partially inside the ore body 61 and partially inside the hangingwall 62. Stress shadows S and high stress zones T are also indicated.
Figure 4k schematically illustrates a view of a vertical cross-section of one form of the Raise Cavingmining method according to the invention provided with raise levels 441,442,443, slot raise 421 andslots 401,402. The slot 401 is developed between raise level 441 and raise level 442. Slot 402 is underdevelopment by means of drilling and blasting in upwards direction from slot raise 421 between raiselevel 442 and raise level 443. Slots 401, 402 are adapted to local hangingwall 62 boundaries. Thereforeslot 401 and 402 are offset in horizontal direction. Moreover, slot 401 and 402 have different inclinations. Additionally, it is shown that the vertical distance between raise levels 441 and 442 and 26raise levels 442 and 443 is different. Figure 4k outlines the adaptability and flexibility of the Raise Caving mine layout to local conditions.
Figure 4l schematically illustrates a horizontal cross-section of one form of the Raise Caving miningmethod according to the invention. The figure provides an overview of Raise Caving at one point intime after the slots 401,402,403,404 have been developed and the stopes 451,452,453 have beenmined. The figure shows that the slots 401,402,403,404 and stopes 451,452,453 are filled with brokenrock mass as described above. The figure shows the Raise Caving mining method in the productionphase. ln this example the slots 401,402,403,404 are developed at the contact of ore body 61 andhangingwall 62. The slots are located in the ore body 61 and/ or in the hangingwall 62. Pillars411,412,413 separate neighboring slots. Slot 401 provides a stress shadow S1 for the production raise431. Compared with the stress shadow S2 adjacent to slots 402, 403, 404 and stopes 451,452,453 thestress shadow S1 adjacent slot 401 is relatively small. Thus, the production raise 431 must be close to the slot 401.
The figure shows that the stope 453 has been mined adjacent to slot 404, which provided a stressshadow and thus a favourable stress environment for the extraction of stope 453. Stope 451 has beenmined adjacent to slot 403, which provided a stress shadow and thus a favourable stress environmentfor the extraction of stope 451. Furthermore, stope 452 was mined after extraction of stope 451 andadjacent to stope 451, which provided a stress shadow and thus a favourable stress environment forthe extraction of stope 452. The shape of the stopes 451,452,453 is variable and can be adapted tolocal conditions and needs. For example, the stope shape is adapted such that stopes end at thecontact of ore body 61 and footwall 63. Thus, the shape of the stopes are adapted to the shape of the ore body.
Moreover, one or several production raises may be used for developing one stope. Because ofextraction of stopes 451, 453 the pillars 412,413 between the slots 402,403,404 are fractured and de-stressed. Accordingly, a stress shadow of regional extent has been created near slots 402,403,404 andnear stopes 451,452,453. This regional stress shadow also extends significantly into the hangingwall62 and footwall 63. The production raises 432,433 were developed inside the said regional stress shadow.
The production raise 431 is located in the center of the production stope. However, production raisesmay alternatively be located offset from the center of the production stope, as illustrated byproduction raises 432, 433. The position of the production raise can be freely selected provided that the raise is located in a de-stressed rock mass located in a favourable stress environment generated 27by at least one of de-stressing slots 401,402,403,404 and/or neighboring stopes 451,452,453.Furthermore, the production raise 431,432,433 may be inclined in relation to a horizontal plane, however the production raise may alternatively be vertically arranged.
Extraction of stopes is performed from production raises 432 and 433, but as shown in the figures, the stopes have not been extracted up to the horizontal cross-section as shown in Figure 4l.
Overall, the form of the method as illustrated in Figure 4l outlines the flexibility and adaptability of theRaise Caving mining method according to the invention. The skilled person realizes that the methodenables that position, orientation, shape and size of the elements of the method, the slot raises, slots,pillars, production raises, stopes, as well as the mining sequence can be flexibly adapted to ore bodygeometry, stress situation and rock mass conditions provided that the advantageous effect that afavourable stress environment is achieved such that problems related to rock mechanics are reduced,and the overall rock pressure situation can be managed. Furthermore, the adaptations of these elements may be carried out on short notice.
Figures 5a to 5c illustrate schematically different arrangements of development of de-stressing slots according to the invention.
Figure 5a provides a schematic isometric view of a slot 501 developed from a slot raise 521 in upwardsdirection by means of drilling and blasting. The slot raise 521 is positioned in the center of slot 501.
First, a slot raise 521 has been developed between raise levels 541,542,543.
The development of slot 501 starts at raise level 541. The raise level 541 comprises drifts 571 arrangedin different directions and slot drawpoints 561. Drifts 571 provide access to slot drawpoints 561, whichare used for drawing broken rock out of slot 501. The slot 501 is developed above another raise level542, which comprises drifts 571 and slot drawpoints. The slot 501 will be further developed until raiselevel 543 and drifts 571 arranged at raise level 543 provide access to the slot raise 521, the platform 102 and the shaft hoist system 104 (not shown in figure). ln Figure 5a it is illustrated that the slot is developed from a raise 521 which is located along the centrallongitudinal axis A1 of the slot 501. However, the slot may alternatively be developed from a raise which is offset from the central longitudinal axis of the slot depending on the circumstances.
Figure 5b provides a schematic isometric view of another arrangement of development of a slotwherein a slot 501 is developed by means of drilling and blasting rounds in a retreat manner between sublevels 5s1,5sz,5s3,5s4,5s5. 28Slot development 501 started between sublevels 581 and 582 and proceeded upwards subsequently.Sublevels comprise drifts 571 in different directions. After slot development passed by a sublevel, slotdrawpoints 561 are developed for drawing broken rock mass from the slot. Moreover, sublevelscomprise a drift 572 before blasting of slot 501. This drift 572 is oriented along axis A2 of slot 501 and is used for drilling and blasting of slot 501.
Figure 5c schematically illustrates one example of a de-stressing slot according to the inventionshowing development of a slot 501. First, a slot raise 521 was developed between raise levels541,542,543. The development of slot 501 started at raise level 541 subsequently. Raise level 541comprises drifts 571 arranged in different directions and slot drawpoints 561. Drifts 571 provide accessto slot drawpoints 561, which are used for drawing broken rock out of slot 501. The slot 501 has been developed above another raise level 542, which comprises drifts 571 and slot drawpoints.
Figure 5c shows that slot 501 could not be further developed from slot raise 521 in upwards directionsfor various reasons. Thus, as slot development cannot proceed, the slot roof 501R is stopped at acertain position. ln order to commence the further slot development, another slot raise 522 isdeveloped between raise levels 542 and 543. From said slot raise 522 drill holes 591 are drilled andcharged with explosives above the slot roof 501R. Drill holes are subsequently fired in order to proceedwith slot development. After the problem is resolved, further development of slot 501 may be conducted from slot raise 521 or slot raise 522. ln another form of the invention the slot raise 522 is used for drilling blast holes into the slot, whichare subsequently blasted. This is particularly advantageous when there is a hang-up in the slot 501 dueto broken rock or ore that is stuck. ln such case drilling and blasting can be carried out from a slot raise 522 outside the slot.
Figures 6a to llb illustrate schematically the overall concept of Raise Caving mining method accordingto the invention and show therefore the application of the Raise Caving mining method in a schematic ore body.
The Raise Caving mining method comprises different types of infrastructure, elements and levels forthe de-stressing and production phase. lt should be noted that for the purpose of illustration thefigures show de-stressing and production infrastructure such as raises, slots, tunnels, drawpoints, rockpasses or ore passes, stopes and levels arranged in the rock mass. However, for the purpose ofillustration, some elements, such as the rock mass, ore body or pillars are indicated only by numbers in some of the figures such as 4c-4g, 4k,6a-b, 7a-b, 8a-b,9a-b,10a-b, 11a-b. 29The Raise Caving mining method can be divided into two phases, namely a de-stressing phase and aproduction phase. Preferably the mining method comprises a de-stressing phase for generating andexpanding the favourable stress environment in the rock mass, in order to protect mininginfrastructure and in particular the infrastructure in the production area, and a production phase forextraction of ore from the ore body, and wherein de-stressing phase and the production phase areintegrated such that in a certain mining area the production phase benefits from the de-stressing phase. The de-stressing phase and production phase may be run in parallel.
Figure 6a schematically i||ustrates a view of one form of the method according to invention showinginitial steps of the method. Figure 6b schematically i||ustrates a line drawing of a further developmentof the form of the method as shown in Figure 6a. Figure 7a schematically i||ustrates a vertical cross-section of a lower part of the view illustrated in Figure 6a and Figure 7b schematically i||ustrates a side view of the form of the method shown in Figure 6b.
Figure 6b shows a slot access level 2, slot raises la,lb,lc, slot 3a, start-slots 4a, 4b and raise levels 5.1,5.2. Figure 6b shows that a slot access level 2 is developed in a rock mass. This slot access level 2comprises drifts 28 giving access to the ore body 61 and especially preparing the development of start-slots 4a,4b and slot 3a. ln this form of the invention, the slot access level 2 is the lowermost level. Afirst slot raise la is developed for example by a conventional raise boring method from a drift Dlarranged on the slot access level 2 and upwards to a drift D2 arranged on a first raise level 5.1 arrangedabove the slot access level 2 in the rock mass. The first slot raise la is thereafter further developed toa drift D3 arranged on the second raise level 5.2 which is located above the first raise level 5.l in therock mass. The slot raise la, and further slot raises lb,lc, are developed in the same way, and mayextend up to several hundred meters upwards. As shown in the figure, the development takes place in a stepwise manner. ln one form of the invention the method comprises that a start-slot 4a and a slot 3a are developed bydrilling and blasting carried out from platform l02 (see Fig. l) operating inside the slot raise la. Blastingof the start-slot 4a and slot 3a is done from the bottom of the start-slot 4a in upwards direction. Astart-slot 4a is developed from the slot raise la in upwards direction by drilling and blasting from thedrift Dl at the slot access level 2 to a predetermined vertical extent above the access level 2. The start-slot 4a generates a stress shadow S in the vicinity of the start-slot 4a which creates a favourable stressenvironment in the rock mass to provide protection for production infrastructure located above the slot access level 2 and adjacent to the start-slot 4a.
The vertical extent of the start-slot 4a is adapted such that the rock mass above the slot access level 2,where production infrastructure will be later developed, will be appropriately and sufficiently de-stressed. The production infrastructure will be developed in the vicinity of the start-slot 4a on a furtherlevel located in the rock mass above the slot access level 2, preferably on a draw level developed inrock mass located in a favourable stress environment generated by start-slots and/or de-stressing slots. ln one form of the invention the draw level coincides with a main haulage level, where the maintransportation system is installed. ln such case the slot access level may also be referred to as main haulage level-1 since the slot access level is arranged below the main haulage level.
As illustrated in Figure 6b, the slot raise la extends further upwards from the start-slot 4a. The slot 3ais developed upwards from the slot raise la by drilling and blasting. The slot 3a starts at the roof 4R ofthe start-slot 4a and extends to the drift on the first raise level 5.1 arranged above the slot access level2. The slot 3a has a slot roof 3R. The cross-sectional area of the slot 3a perpendicular to the longitudinalaxis A1 of the slot is smaller than the cross-sectional area of the start-slot 4a perpendicular to thelongitudinal axis A1 of the start-slot. ln particular, the width of the slot 3a is smaller than the width ofthe start-slot 4a. The width of the slot 3a or start-slot 4a is the extension of the slot 3a or start-slot 4ain direction of axis A2, respectively. As an example, the start-slots as described in the present methodare approx. 100 m wide, and the slots are approx. 50 m wide. However, the slot and start-slotdimensions respectively depend on several parameters, such as the circumstances, the ore body shapeor the stress situation at the location. Furthermore, slot drawpoints 21 are arranged on the slot accesslevel 2 and developed into the start-slot 4a to draw broken rock mass from the start-slot 4a and slot 3a.
Typically, the start-slot is located below the slot, however in another form of the invention a first de-stressing slot having a certain width is first developed from the slot raise by drilling and blasting inupwards direction from the drift arranged on the slot access level to a first predetermined verticalextent thereafter the width of the slot is increased such that a start-slot is developed from the slotraise by drilling and blasting in upwards direction from the roof of the slot (not shown in figures) to asecond predetermined vertical extent. Thereafter, above the start-slot, a second de-stressing slot isdeveloped from the slot raise by drilling and blasting in upwards direction from the roof of the start- slot towards the drift on a raise level. 31ln yet another form of the invention the start-slot begins from a draw level arranged above the slotaccess level and extend upwards to a predetermined vertical extent. Thereafter, a slot is developed upwards from the roof of the start-slot 4R towards a raise level (not shown in figures).
Figure 6b further shows that a second slot raise lb is developed from a drift arranged on the slot accesslevel 2 and upwards to a drift D2 arranged on the raise level 5.1. The second slot raise lb is developedat a distance from the first slot raise la. The distance is determined by circumstances such as ore bodyshape, rock mass conditions, stress situation and mining directions. Moreover, a second start-slot 4bis under development from the second slot raise lb by drilling and blasting in upwards directiontowards the drift D2 on the raise level 5.1. Slot drawpoints 21 are continued to be developed at the slot access level 2.
Figure 6b shows further that a continuous start-slot 20 is created by joining the two adjacent start-slots 4a and 4b. Thus, the start-slots 4a and 4b form the continuous start-slot 20 in order to generatea stress shadow S to provide protection by creating a favourable stress environment in the rock massfor the production infrastructure that will be developed above the slot access level 2 and in the vicinityof the continuous start-slot 20. As an example, the continuous start-slot 20 has a vertical extent of approximatively 100 m. ln another form of the invention, adjacent start-slots may be separated by an appropriately sized crushpillar. This crush pillar crushes due to prevailing stresses. Due to this crushing, the crush pillar de-stresses. As a consequence, the stress shadow is also present in the vicinity of de-stressed crush pillar.
Thereby a persistent stress shadow is created in the vicinity of start-slots.
Figure 6b shows that the Raise Caving mining method comprises developing one or more raise levels5.1, 5.2 arranged in the rock mass above the slot access level. The second raise level 5.2 is arrangedabove the first raise level 5.1 as illustrated in the figures. The vertical distance between the first raiselevel 5.1 and second raise level 5.2 is adapted to local needs and technical possibilities and may be up to 200 m to 300 m. lt should be noted that the references ”first raise level" and ”second raise level" only indicates theorder of the raise levels that the slots and slot raises are developed to, and the position of each raiselevel relative to the slot access level. These raise levels do not preclude that additional drifts and/or levels are arranged in between the slot access level and the raise levels.
Figure 6b further shows that the slots 3a and start-slots 4a,4b are inclined. By inclined is meant that the longitudinal axis A1 of slots and start-slots are directed at least 40 degrees from the horizontal 32plane. lt should be noted that the axis A2 of slot and start-slots does not have to be oriented in strikedirection of the ore body. Thus, the axis A2 of slot and start-slots may also be oriented out of strike direction of the ore body The slots 3a and start-slots 4a,4b generate a stress-shadow S at certain locations in the rock massadjacent to the slot and start-slots in order to create a favourable stress environment to provideprotection for mining infrastructure. Production infrastructure that is later developed in the favourablestress environment provided by the slot and start-slots is thereby protected from high stresses andseismic energy release. Thus, the de-stressing slot 3a and start-slots 4a,4b substantially decrease oreven prevent high stress and/or consequences of seismic energy releases in the part of the rock mass where the stress-shadow S is generated (not shown in this figure)..
Figure 8a schematically illustrates a view of one form of the method according to invention showingfurther progress of de-stressing of the rock mass and initial preparation of the production phase. Figure8b schematically illustrates a line drawing of the form of the method as shown in Figure 8a. Figure 9aschematically illustrates a vertical cross-section of a lower part of the view of the slot 3a and the start-slot 4a illustrated in Figure 8a and Figure 9b schematically illustrates a vertical cross-section of slot 3ashown in Figure 9a. Figure 6b illustrates the de-stressing phase at an early stage of the Raise Cavingmethod according to the invention, whereas Figure 8b illustrates a more advanced stage of the de- stressing phase, in which also some parts of production infrastructure have been developed.
The Raise Caving mining method for mining ore from an ore body 61 comprises at least two slots 3aand 3b developed in a rock mass. The slots 3a, 3b are placed next to the hangingwall 62 in Figure 8b.Figure 8b shows that the slots 3a-3b are developed from slot raises la-lb. Pillar 9a separatesneighbouring slots 3a,3b. Each slot raise is developed stepwise, in a first step the raise is developedfrom the slot access level 2 to a raise level 5.1, and then further to a raise level 5.2. Also, the slots 3a,3bare developed stepwise. The slot 3a is developed from the first slot raise la in upwards direction bydrilling and blasting from the roof of the start-slot 4R to the raise level 5.1 and then further upwardstowards the raise level 5.2 to ensure that the rock mass is de-stressed adjacent the slot 3a and toprovide a favourable stress environment for the subsequent development of production infrastructure adjacent to the slot 3a.
The pillar 9a is left between slots 3a and 3b. The pillar 9a provides control of the stress magnitude inthe rock mass at the position of slot raise lc, which is used for subsequent development of the nextslot. Moreover, the pillar 9a provides control of the stress magnitude near slot roofs of slots 3a and 3b. Thereby the pillar 9a creates a favourable stress environment to enable further development of 33 slots 3a and 3b and to enable development of the next slot from slot raise lc as well as the vertical extension of slot raise lc.
Figure 8b further illustrates that after the roof 3R of the de-stressing slot 3a has advanced beyond alevel, for example beyond raise level 5.1, this raise level 5.1 may be used for creation of additional slot drawpoints 21 into the slot 3a thereby stimulating and facilitating rock flow in the slot.
Figure 9b shows a vertical cross-section of the slot 3a and the start-slot 4a and a draw level 8 withproduction infrastructure located in the ore body 61. The figure shows that the slot 3a is developed in the contact area between the ore body 61 and the hangingwall 62.
As illustrated in Figure 8b, the start-slots 4a-4c are developed from the slot access level 2 to extend to a predetermined vertical extent above a draw level 8, which is located above the slot access level 2.
Figures 8b shows that a draw level 8 is developed and located in the favourable stress environment inthe rock mass which is de-stressed by the start-slots and slots. The draw level 8 is developed in the de-stressed rock mass above the slot access level 2, this is advantageous in that the majority of long-termproduction infrastructure is situated at the draw level 8. The distance between the slot access level 2and the draw level 8 depends on several factors, such as prevailing ore body shapes, stress situation and rock mass conditions.
As shown in Figures 8b and 9b the mining infrastructure at the slot access level 2 comprises drifts 28and slot drawpoints 21 for drawing swell during development of start-slots and slots. The drawpoint21,22 refers to the excavated structure, through which the caved or broken rock mass is loaded andremoved from the slot or stope. After slot development has progressed upwards from the slot accesslevel 2 and after the draw level 8 has been developed, slot drawpoints 21 may also be developed atthe draw level 8. Thereafter the slot access level 2 is no longer required and may therefore be abandoned.
The slot drawpoints 21 are developed into the start-slots 4a,4b,4c at the draw level 8. Furthermore,slot drawpoints 21 are also developed from the drifts 28 on the raise levels 5.1 into the slots 3a,3b todraw rock mass from the slots. However, in another form of the method according to the invention the slot drawpoints are not developed into the slots or start-slots.
The draw level 8 is developed and located in direct connection with the area where the productionstope subsequently will be mined. The draw level 8 is used for extracting ore from the productionstopes. The draw level 8 comprises draw infrastructure such as slot drawpoints 21, stope drawpoints 22 and drifts 28, wherein the stope drawpoints 22 may be long-term and stationary. The draw level 34layout is comparable to a draw level layout used in prior art block caving method, however the drawlevel 8 developed for the present method offers much more flexibility to configure draw bell shape and drawpoint arrangement (not shown in the figures).
The stopes mined by raises could also replace a traditional undercut in block and panel caving. ln thiscase, the size of the stope roof would be increased, until caving is initiated. Thus, raises equipped withappropriate machinery above an active cave furthermore provide possibilities for pre-conditioning, cave advance monitoring, facilitating cave advance and steering of caving front.
The Figure 8b illustrates that the Raise Caving mining method further comprises a step of developinga production raise 6a in the ore body 61 in the favourable stress environment created adjacent theslot 3a and start-slot 4a. The production raise is developed between a drift located on the draw level8 and a drift on the raise level 5.1 by conventional methods, such as for example raise boring. The raiselevel 5.1 and the raise level 5.2 are then functioning as top levels of slot raises 1a,1b,1c and productionraise 6a, respectively. The hoist system 104 (see fig. 1) is installed at the top level of slot and production raises. Stope drawpoints 22 are developed on the draw level 8 adjacent the continuous start-slot 20.
Figure 10a schematically illustrates a view of one form of steps of the Raise Caving mining methodaccording to the invention showing further de-stressing in order to create a favourable stressenvironment and advanced extraction of ore in the production phase and figure 10b schematicallyillustrates a line drawing of a further development of the form shown in Figure 10a. Figure 11aschematically illustrates a lower part of a vertical side view through stope 13a of the form of the RaiseCaving mining method illustrated in Figure 10a and Figure llb schematically illustrates a lower part of a side view of stope 13a of the view as illustrated in Figure 10b.
As illustrated in Figure 10b the Raise Caving mining method comprises that pillars 9a,9b,9c are leftbetween the adjacent slots 3a,3b,3c,3d to separate adjacent slots. Each pillar is a piece of rock mass,which controls surrounding rock mass during the de-stressing phase and production phase. ln thefigures, for the purpose of illustration, the pillars are indicated as gaps between the slots 3a,3b,3c,3dand 3a,3b,3c,3d respectively. Each pillar 9a,9b,9c controls stress magnitudes and seismicity around thede-stressing slots and provides control of stress magnitude in the rock mass at the position of thefollowing slot thereby creating a favourable stress environment to enable development of thefollowing slots. Thus, the pillar establishes a favourable stress environment for raise and slotdevelopment for the next de-stressing slot according to the mining sequence. As an example thedistance between the center of two adjacently arranged slot raises 1a,1b,1c,1d may be approx. 100 m, thus leaving pillars 9a,9b,9c which are approx. 50 m wide and 10 m high between adjacent slots, thereby separating the slots and providing a favourable stress environment for development of thenext de-stressing slot. The width of the pillar is its extension in direction of axis P2 and the height of the pillar is its extension in direction of the axis P3.
The Raise Caving mining method is advantageous in that the amount of infrastructure required for the de-stressing phase is limited and rather small in comparison to the production phase.
Figure 10b shows that the Raise Caving mining method comprises a step of mining by progressingupwards the production stope 13a from the production raise 6a and a step of drawing ore from theproduction stope 13a through stope drawpoints 22. The mining is carried out by drilling and blastingfrom the production raise. Also, production stopes 13b and 13c are mined in upwards direction bydrilling and blasting in production raises 6b,6c. Moreover, figure 10b shows that mining progressesupwards stepwise in the parts of the ore body that are de-stressed by the slots 3a,3b,3c,3d therebyprovided with a favourable stress environment for protection of the production infrastructure. Eachproduction raise 6a,6b,6c is developed between a drift arranged on the draw level 8 stepwise to the raise levels 5.1,5.2 arranged above the draw level 8.
The actual mining of the production stope 13a, 13b, 13c is typically carried out by drilling and blasting,where the drilling of drill holes and blasting the drill holes is carried out from the respective productionraise 6a,6b,6c. This is very advantageous in that safe and efficient stoping can be achieved, and thestoping can be carried out remotely controlled or automated. The blast holes 107 could be either horizontal as shown in Figure lb or inclined to achieve a better breakage in blasting. ln another form of the method, the step of mining of the production stope 13a-13c is carried out bycaving. The stope is typically run in drilling and blasting mode. However, a stope can also be excavated by means of caving.
Figure 10b shows that the slots 3a,3b,3c have been developed above the stope roof of respectiveproduction stopes 13a,13b,13c. Specifically, the slot roof 3R of slot 3a has been developed above thestope roof 13R. Thereby slots 3a,3b,3c provide a favourable stress environment for at least the production raises 6a,6b,6c and production stopes 13a,13b,13c.
Figure 10b shows that the production stope 13a has been mined above the raise level 5.2. ln order tostimulate ore flow in the stope intermediate draw levels 5.1,5.1.1,5.2,5.2.1 may be developed.Moreover, the installation of one or more intermediate draw levels 5.1,5.1.1,5.2,5.2.1 may becomenecessary, if the ore flow to the draw level 8 cannot be guaranteed due to ore body shape or ore body inclination. 36ln the form of the Raise Caving mining method shown in Figure 10b, the former raise levels 5.1 and 5.2have partially been converted to intermediate draw levels 5.1 and 5.2 in areas where the stopes13a,13b have been developed above the draw levels 5.1,5.2. Furthermore, additional intermediatedraw levels 5.1.1 and 5.2.1 have been developed. Each intermediate draw level 5.1,5.1.1,5.2,5.2.1 isprovided with at least one stope drawpoint 22. The production stope 13a generates a stress-shadow Sin the vicinity of the stope. Thus, a favourable stress environment is created which is advantageous inthat it provides protection for further production infrastructure, such as intermediate draw levels5.1,5.1.1,5.2,5.2.1 and ore pass lla. Preferably the intermediate draw levels 5.1,5.1.1,5.2,5.2.1 aredeveloped after the stope roof 13R has advanced above planned position of respective intermediatedraw levels 5.1,5.1.1,5.2,5.2.1 so that abutment stress damage to intermediate draw levels .1,5.1.1,5.2,5.2.1 and stope drawpoints 22 is prevented.
Figure 10b further illustrates rock passes lla and llb. Rock pass lla is developed between the drawlevel 8 and intermediate draw levels 5.1,5.1.1,5.2,5.2.1 in order to transport rock mass drawn fromstope 13a at stope drawpoints 22 arranged on the intermediate draw levels 5.1,5.1.1,5.2,5.2.1 to thedraw level 8 below. The rock pass is a vertical or inclined excavation for transporting ore by means ofgravity. The rock passes lla, llb, may be developed by means of for example raise boring and areused for transporting ore from intermediate draw levels 5.1,5.1.1,5.2,5.2.1 to the draw level 8. Rockpasses lla, llb are developed at a later stage in the production phase in a favourable stressenvironment, which is generated by the adjacent production stopes 13a,13b. Preferably, the rock passes are developed stepwise together with the intermediate draw levels. ln another form of the invention, at least one rock pass lla, llb is developed delayed in between anintermediate draw level 5.1,5.1.1,5.2,5.2.1 and another receiving level arranged below the saidintermediate draw level 5.1,5.1.1,5.2,5.2.1 in favourable stress environment created by at least oneproduction stope 13a,13b. By delayed development is meant that the rock pass is developed subsequent to developing of the production stope.
The pillars provide initial support for the hangingwall. Thus, extraction of at least one of the pillars9a,9b,9c removes the support for the hangingwall 62, which causes the hangingwall 62 to cave. Thus,caved hangingwall masses fill up the stope. ln the process of drawing a fully progressed stope, cavedmasses fill up the stope completely. Figure 10b shows that as the steps of stoping progress, also thepillars 9a,9b,9c are extracted as part of the stoping process removing the temporary support from thehangingwall 62, which is provided by pillar 9a,9b,9c. Preferably, the pillars 9a,9b,9c are extracted byweakening each pillar actively by drilling and blasting from at least one production raise. ln another form of the invention, the pillars 9a,9b,9c are extracted by degrading the pillar strength by decreasing 37the pillar width-to-height ratio due to nearby stope mining and facilitating pillar yielding and self-destruction. The width of a pillar is its extension in the direction of axis P2 and the height of a pillar isits extension in the direction of axis P3. ln one form of the invention, extraction of a pillar is achievedby arranging a production raise in or near the de-stressed pillar. ln another form one form of the invention a pillar 9a,9b,9c can be extracted by means of drilling and blasting or by means of caving. ln one form ofthe invention, only parts of the hangingwall 62 adjacent to the extracted pillar is allowed to cave in order to subsequently fill up the mined-out production stope adjacent to the extracted pillar. ln one form of the invention the method comprises a step of delaying hangingwall caving due topresence of broken rock mass in the at least one slot 3a,3b,3c,3d and/or in the at least one productionstope 13a,13b,13c, and/or presence of at least one pillar 9a,9b,9c and/or implemented drawstrategies. Thus, the broken rock inside the production stopes 13a,13b,13c functions as a temporary hangingwall support and thus slows down caving of hangingwall 62 and dilution. ln another form of the invention, a stope is connected to previously caved masses, which start to flow into the stope as drawing of ore from the stope progresses. lt should be noted that in Figure 10b there are no pillars remaining between the stopes and slots, thusthe stopes 13a,13b,13c are developed adjacent to respective slot 3a,3b,3c. However, in another formofthe invention, the method comprises leaving a temporary pillar arranged in between the production stope and the respective slot that is located adjacent the production stope. ln Figure 10b there is no remaining pillar between the stopes 13a-13b. However, in another form of the invention the method comprises leaving a temporary pillar in between adjacent production stopes. ln another form of the invention, slots may be located inside the ore body such that a portion of theore body is left between the slots and the hangingwall. Thus, extraction of at least one of the pillars causes caving of the ore body between the slot and the hangingwall.
The Raise Caving mining method is flexible and applicable to various ore body shapes and sizes. Maininfrastructure such as hoists, main haulage drifts or workshops, are not shown in the figures forsimplification. Outlined excavation dimensions and geometries are based on preliminary analysis andprovide only a rough estimation of dimensions and geometries in the Raise Caving mining methodaccording to the invention. The dimensions mentioned herein are only given as an example for thepurpose of describing the invention and are not limiting to the invention. lt is foreseen that the RaiseCaving mining method may be applied at much larger scales than the given example. Geometries of slots, start-slots, stopes, drawpoints and draw levels can vary, because they are adapted to prevailing 38mining environment, which comprises amongst others the rock mass conditions, ore body shape and the stress situation.
For example, in the figures it is illustrated that the de-stressing slots 3a,3b,3c,3d the start-slots4a,4b,4c,4d and the productions stopes 13a,13b,13c have a rectangular cross-section. However, inanother form of the invention, the de-stressing slots 3a,3b,3c,3d and start-slots 4a,4b,4c,4d may alsohave elliptical or at least elongated cross-section. ln one form of the invention, at least one of theproduction stopes 13a,13b,13c,13d may have elliptical, circular, or other irregular cross-sections.Furthermore, the inclination of start-slots, slots and stopes could be varied for adaptation purposes as indicated in Figure 4c-g and 4k.
Figure 6a, 6b illustrate the de-stressing phase at an early stage of the Raise Caving mining methodaccording to the invention, and Figure 8a, 8b illustrate a more advanced stage of the de-stressingphase. Figure 10a, 10b mainly illustrate the production phase and extraction of ore from the ore body.The figures are simplified to facilitate the understanding of the method; therefore, the figures only show a small part of a rock mass and Raise Caving mining method.
Figure 10a, 10b illustrate stepwise development of the de-stressing infrastructure, such as slot raises1a,1b,1c,1d, slot access level 2, raise levels 5.1,5.2 and slot drawpoints 21, and the productioninfrastructure, such as draw level 8, stope drawpoints 22, intermediate draw levels 5.1,5.1.1,5.2,5.2.1,rock passes 11a,11b and production raises 6a,6b,6c. Furthermore, Figure 10a,10b illustrate thedevelopment of slots 3a,3b,3c,3d and start-slots 4a,4b,4c,4d and the mining of the stopes 13a,13b,13caccording to the invention. lt is essential that the slot development has progressed sufficiently suchthat a favourable stress environment in the rock mass is created to ensure safe development and expansion of production infrastructure and mining of stopes.
Specifically, the Raise Caving mining method further comprises implementing a mining sequence forproviding the favourable stress environment and for controlling mining induced seismicity in the activemining area. The term "mining sequence" refers to the sequence of mining activities, which should befollowed in order to achieve the overall goals of extraction of the ore body as complete as possible,the safety and economy of the mining operation, considering factors, rock mechanical constraints andother factors. Preferably, the mining sequence is adapted to and determined by production and/or orebody geometry and/or rock mechanics consideration thereby controlling mining induced seismicity and high stresses.
Preferably the mining sequence comprises development of the slot 3a,3b,3c,3d ahead of development of the production stopes 13a,13b,13c respectively where the roof of the slot 3R is a predetermined 39vertical distance ahead of the roof of the production stope 13R, in order to ensure that the productionstopes 13a,13b,13c are mined in de-stressed rock mass. lt should be noted that the slots do not haveto be developed to the full lenght prior to developing the production stope adjacent the respective slot.
Several production stopes 13a,13b,13c may be in production at the same time, however a verticaldistance between the roofs of neighboring production stopes 13a,13b,13c is recommended in orderto avoid negative interrelations. Production stope footprints of more than 1000 m2 appear to be feasible at present.
Figures 3, 4l, and 6-10, 11 show schematically different examples of mining sequences of the de-stressing phase and the production phase according to the Raise Caving mining method for providingthe favourable stress environment. By implementing a mining sequence, mining induced seismicity and high stresses can be controlled in the active mining area.
The Raise Caving mining method, as shown in the figures illustrates only a limited active mining area.However, the mining method may extend further both vertically and horizontally, not shown in thefigures. Preferably, the steps of the method are repeated to a larger area until the desired part of the ore body has been extracted.
The Raise Caving mining method according to the present invention is a flexible method allowing forchanges in mine layout and mining sequence on short notice and according to needs, production, ore body geometry, prevailing rock mass conditions, prevailing stress situation etc.
The mine layout such as position of slots, stopes and raises, inclination of raises, level spacing, shapeof slots, start-slots and stopes, etc. and other infrastructure can be adapted to local ore body shapes,stress situation, rock mass properties etc. Preferably, the mine layout is adapted to and determined by production, ore body geometry, rock mass conditions, stress situation etc.
Preferably, the mine layout and the mining sequence can be adjusted on short notice to account forunforeseen circumstances and can be adapted flexibly. E.g. site-specific drill and blast patterns,adaptable stope and slot cross-section, adaptable slot orientations, adaptable draw strategies etc. maybe implemented. Furthermore, cross-sections of stopes can be adjusted to ore body boundaries with orientation and length of individual drill holes.
Moreover, changes in the mine layout and the mining sequence can be made on a short to mediumterm notice, because Raise Caving mining method requires a minimum amount of infrastructure development in advance. This circumstance is a powerful possibility to adopt mine design to gained experiences dynamically. However, rock mechanical considerations must be considered in such aflexible mine design. For example, production raises must be placed in de-stressed rock mass or rockmass having favourable stress environment. Overall, the flexibility in the Raise Caving mining methodis much improved in comparison to prior art caving methods. Prior art caving methods are very rigidand do not allow changes at all or have very limited or expensive possibilities for adaptions after infrastructure development started or caving was initiated, respectively.
Certain elements of Raise Caving mining method could be applied in other ways as well. Preferably, atleast one de-stressing slot is implemented in another mining method such as block and panel cavingmethod, for generating a stress-shadow and creating a favourable stress environment to provide protection of critical infrastructure in such mining method. ln another form of the invention at least one production stope is connected to a previously caved areathereby allowing previously caved masses to fill up the at least one production stope. For example, thestope roof may be connected by the stoping process to an area located above the stope, wherein said area has caved earlier.
Furthermore, in another form of the invention parts of a stope are backfilled. This backfill providessupport to the surrounding rock mass. Moreover, the stope can be used as a waste storage instead of transporting waste to other locations.
Furthermore, in one form of the invention the method comprises a step of monitoring the productionstopes 13a,13b,13c via the production raises 6a,6b,6c. Efficient and reliable control of the stopingprocess is thereby achieved. Preferably, cave stall and the associated risk of an air blast are also controlled via the production raises 6a,6b,6c using said monitoring methods.
The foregoing description of the preferred embodiments is provided for illustrative and descriptivepurposes. lt 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. Theembodiments have been chosen and described in order to best explain the principles and practicalapplications, and hence make it possible for specialists to understand the invention for various embodiments and with the various modifications that are applicable to its intended use.
Claims (52)
1. Raise Caving mining method for mining ore from an ore body (61) comprising the following steps: -developing at least two slots (3a,3b;301,302;402,403) in a rock mass and leaving a pillar(9a;311;412) of rock mass to separate adjacent slots (3a,3b;301,302;402,403) in orderto create a favourable stress environment in the rock mass to provide protection for mining infrastructure, -developing at least one production raise (6a,6b) within the rock mass providing the favourable stress environment, -progressing upwards by mining at least one production stope(13a,13b;351,353;451,453) from the at least one production raise (6a,6b), and drawingore from the production stope (13a,13b;351,353;451,453). The method according to claim 1 wherein each slot (3a,3b;301,302;402,403) generatesa stress-shadow (S) at certain locations adjacent to the slot (3a,3b;301,302;402,403),wherein said stress-shadow (S) de-stresses the rock mass thereby creating said favourable stress environment. The method according to claim 1 or 2 wherein said production raise (6a,6b) isdeveloped in the favourable stress environment at certain locations created adjacent said slots (3a,3b). The method according to any of the previous claims wherein said pillar (9a;311;412)provides control of stress magnitude in the rock mass at the position in the rock masswhere the following slot (3b;353;453) will subsequently be developed therebycreating a favourable stress environment to enable development of the ; following slot (3b;353;453).42The method according to any of the previous c|aims comprising a step of implementinga mining sequence for providing the favourable stress environment in the active mining area. The method according to c|aim 5 wherein the mining sequence is a means for contro||ing of mining induced seismicity in the active mining area. The method according to any of the previous c|aims comprising a step of developing atleast one slot (501) from a drift (571) arranged on a first sublevel (581) by means ofdrilling and blasting rounds in a retreat manner upwards to a drift (572) arranged on a second sublevel (582) arranged above the first sublevel (581) in the rock mass. The method according to any of the previous c|aims comprising a step of developing atleast one slot raise (1a,1b,1c) from a drift arranged on a slot access level (2) upwardsto a drift arranged on a level (5.1) arranged above the slot access level (2) in the rock maSS. The method according to c|aim 8 comprising a step of developing at least one of saidslots (3a,3b,3c) from said at least one slot raise (1a,1b,1c) by blasting upwards fromthe drift arranged on the slot access level (2) to the drift arranged on the level (5.1) arranged above the slot access level (2) in the rock mass. The method according to any of the previous c|aims comprising a step of developing atleast one start-slot (4a,4b,4c) from the slot access level (2) to a predetermined verticalextent in order to generate a stress-shadow S to provide protection for production infrastructure located above the slot access level (2). The method according to c|aim 9 wherein said start-slot (4a,4b,4c) is developed fromat least one slot raise (1a,1b,1c) by blasting upwards along the slot raise from the drift arranged at the slot access level (2) to the predetermined vertical extent.43The method according to claim 10 or 11 comprising a step of developing a continuousstart-slot (20) from at least two start-slots (4a,4b,4c,4d) in order to generate a stress-shadow S to provide protection for production infrastructure located above the slot access level and adjacent to the start-slot. The method according to any of the previous claims comprising a step of developing atleast one of the slots (3a,3b,3c) from the roof (4R) of one of the start-slots (4a,4b,4c),wherein the area of the slot roof (3R) is smaller than the area ofthe start-slot roof (4R). The method according to any of the previous claims wherein at least one of said slots (3a,3b,3c) is vertical or inclined. The method according to any of the previous claims wherein at least one of said slots(3a,3b,3c) is arranged in a contact area between the ore body (61) and the surrounding rock mass formations. The method according to any of the previous claims wherein at least one of said slots (3a,3b,3c) is arranged inside the ore body (61). The method according to any ofthe previous claims wherein at least one of said slots (3a,3b,3c) is arranged outside the ore body (61). The method according to any of the previous claims comprising a step of developing a draw level (8) in rock mass located in a favourable stress environment. The method according to any ofthe previous claims wherein the draw level (8)comprises draw infrastructure such as slot drawpoints (21), stope drawpoints (22) and drifts.44The method according to any of the previous claims wherein the draw level (8) comprises drawpoints (21,22) which are long-term and stationary. The method according to any of the previous claims comprising a step of developing slot drawpoints (21) into the slots and/or start-slots at the draw level (8). The method according to any of the previous claims wherein the production stope(13a, 13b, 13c) generates a favourable stress environment which protects mining infrastructure in the vicinity of the production stope. The method according to any of the previous claims wherein the interaction of morethan one production stope (13a,13b,13c) generates a regional favourable stress environment for mining infrastructure. The method according to claim 23 wherein the ongoing production process increases the extent ofthe regional favourable stress environment. The method according to any of the previous claims comprising a step of developing anintermediate draw level (5.1, 5.1.1, 5.2, 5.2.1) in order to improve extraction of ore from the stope. The method according to any of the previous claims comprising a step of developingslot drawpoints (21) into the slots and/or start-slots at an intermediate draw level (5.1, 5.1.1, 5.2, 5.2.1). The method according to any of the previous claims comprising a step of delayeddevelopment of at least one rock pass (11a, 11b), in between an intermediate drawlevel (5.1, 5.1.1, 5.2, 5.2.1) and another receiving level arranged below saidintermediate draw level (5.1, 5.1.1, 5.2, 5.2.1) in favourable stress environment created by at least one production stope (13a,13b).The method according to any of the previous claims comprising a step of developmentof at least one horizontal or inclined haulage tunnel, in between an intermediate drawlevel (5.1, 5.1.1, 5.2, 5.2.1) and another level below the said intermediate draw level(5.1, 5.1.1, 5.2, 5.2.1) in favourable stress environment created by at least one production stope (13a,13b). The method according to any of the previous claims comprising a step of mining the production stope (13a) by drilling and blasting. The method according to any of the previous claims comprising a step of mining the production stope (13a) by caving. The method according to any of the previous claims comprising a step of extracting a pillar (9a, 9b, 9c). The method according to claim 31 comprising a step of extracting said pillar (9a,9b,9c)by weakening the pillar actively by blasting from at least one production raise (6a,6b,6c). The method according to claims 31 comprising a step of extracting said pillar (9a,9b,9c)by degrading the pillar strength by decreasing the pillar width-to-height ratio due to nearby stope mining and facilitating pillar yielding and self-destruction. The method according to any of the previous claims comprising a step of extracting ade-stressed pillar (9a,9b,9c) by arranging a production raise in or near the de-stressed pillar. The method according to any of the previous claims comprising a step of extracting a pillar (9a,9b,9c) by means of caving.46The method according to any of the previous c|aims comprising a step of extracting a pillar (9a,9b,9c) by means of drilling and blasting. The method according to any of the previous c|aims comprising a step of connecting atleast one production stope (13a,13b,13c) to previously caved area thereby allowing previously caved masses to fill up the at least one production stope. The method according to any of the previous c|aims comprising a step of caving partsofthe hangingwall (62), in order to fill up at least a part of at least one mined out production stope. The method according to any of the previous c|aims comprising a step of caving thehangingwall (62) facilitated by extraction of pillars (9a,9b,9c) thereby removing the hangingwall support provided by the pillars. The method according to any of the previous c|aims comprising a step of caving of theore body (61) between the overhand side ofthe slot wall and the hangingwall (62), wherein the caving is caused by extraction of the pillars (9a,9b,9c). The method according to any of the previous c|aims comprising a step of developing a slot (501) from a raise (522), where the raise (522) is not located inside the slot (501). The method according to any of the previous c|aims comprising preventing prematurecaving of hangingwall by the presence of broken rock mass inside the slots and/or sto pe. The mining method according to any of the previous c|aims comprising a de-stressingphase for generating and expanding the favourable stress environment in the rockmass, to protect mining infrastructure, in particular the infrastructure in the production area, and a production phase for extraction of ore from the ore body (61),47and wherein de-stressing phase and the production phase are integrated such that in a certain mining area the production phase benefits from the de-stressing phase. The method according to any of the previous claims comprising a step of implementingat least one slot (3a,3b,3c) for de-stressing rock mass and protecting critical infrastructure in another mining method. The method according to any of the previous claims wherein the mining geometry is adapted to and determined by production and/or ore body geometry. The method according to any of the previous claims wherein the mining sequence isadapted to and determined by production and/or ore body geometry and/or rockmechanics consideration thereby controlling mining induced seismicity and high StFeSSeS. The method according to any of the previous claims wherein the mine layout,infrastructure position and mining sequence can be adapted on short notice to account for unforeseen circumstances. The mining method according to any of the previous claims wherein the miningsequence comprises development of the slot (3a,3b,3c) ahead of development of therespective production stope (13a,13b,13c) where the roof of the slot is apredetermined vertical distance ahead of the roof of the production stope, such that the production stope is mined in favourable stress environment. The method according to any of the previous claims comprising a step of monitoring the production stope (13a,13b,13c) via the production raise. The method according to any of the previous claims comprising a step of controllingrisk of air blast and cave stall in the production stope (13a,13b,13c) via the production raise.The method according to any of the previous c|aims comprising repeating the steps of the method to a larger area in the rock mass, to exploit the ore body. The method according to any of the previous c|aims comprising a step of backfilling parts ofthe production stope (13a,13b,13c).
Priority Applications (8)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA3183505A CA3183505A1 (en) | 2020-05-20 | 2021-05-20 | Raise caving method for mining an ore from an ore body, and a mining infrastructure, monitoring system, machinery, control system and data medium therefor |
| BR112022023583A BR112022023583A2 (en) | 2020-05-20 | 2021-05-20 | MINING METHOD FOR MINING ORE FROM AN ORE BODY |
| EP21808020.8A EP4153842A4 (en) | 2020-05-20 | 2021-05-20 | Raise caving method for mining an ore from an ore body, and a mining infrastructure, monitoring system, machinery, control system and data medium therefor |
| US17/999,199 US20230228193A1 (en) | 2020-05-20 | 2021-05-20 | Raise caving method for mining an ore from an ore body, and a mining infrastructure, monitoring system, machinery, control system and data medium therefor |
| CN202180049969.6A CN116034210A (en) | 2020-05-20 | 2021-05-20 | Patio breakout method for mining ore from ore bodies, mining infrastructure, monitoring system, machine, control system and data medium |
| PCT/SE2021/050475 WO2021236000A1 (en) | 2020-05-20 | 2021-05-20 | Raise caving method for mining an ore from an ore body, and a mining infrastructure, monitoring system, machinery, control system and data medium therefor |
| AU2021276092A AU2021276092A1 (en) | 2020-05-20 | 2021-05-20 | Raise caving method for mining an ore from an ore body, and a mining infrastructure, monitoring system, machinery, control system and data medium therefor |
| CL2022003273A CL2022003273A1 (en) | 2020-05-20 | 2022-11-21 | Cave excavation method for extracting a mineral from a deposit, and a mining infrastructure, monitoring system, machinery, control system and data medium therefor |
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| SE2050595 | 2020-05-20 |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN100353029C (en) * | 2006-09-30 | 2007-12-05 | 长沙矿山研究院 | Panel Unloading Layered Filling Mining Method |
| WO2011100808A1 (en) * | 2010-02-22 | 2011-08-25 | Technological Resources Pty. Limited | Underground mining |
| CN106640080B (en) * | 2017-02-17 | 2018-06-01 | 中南大学 | Under a kind of deep high stress environment mining methods are arranged from steady gallery shape stope |
| CN106894817B (en) * | 2017-03-03 | 2018-11-23 | 中南大学 | A kind of mechanization Upward slicing wedging mixed filling mining codes |
Family Cites Families (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4581712A (en) * | 1982-11-10 | 1986-04-08 | Perry Huey J | Roof pressure monitoring system |
| SE502693C2 (en) * | 1994-04-29 | 1995-12-11 | Alimak Ab | Methods and apparatus for quarrying |
| AP3323A (en) * | 2009-09-29 | 2015-06-30 | Orica Explosives Tech Pty Ltd | A method of underground rock blasting |
| CA2897640A1 (en) * | 2013-01-11 | 2014-07-17 | Joy Mm Delaware, Inc. | Continuous-extraction mining system |
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- 2021-05-12 SE SE2150606A patent/SE544562C2/en unknown
Patent Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN100353029C (en) * | 2006-09-30 | 2007-12-05 | 长沙矿山研究院 | Panel Unloading Layered Filling Mining Method |
| WO2011100808A1 (en) * | 2010-02-22 | 2011-08-25 | Technological Resources Pty. Limited | Underground mining |
| CN106640080B (en) * | 2017-02-17 | 2018-06-01 | 中南大学 | Under a kind of deep high stress environment mining methods are arranged from steady gallery shape stope |
| CN106894817B (en) * | 2017-03-03 | 2018-11-23 | 中南大学 | A kind of mechanization Upward slicing wedging mixed filling mining codes |
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