Method and system for adjusting a drill plan

Abstract

The disclosure relates to a method (300) performed by a control arrangement for adjusting a drill plan, the drill plan defining a plurality of holes to be drilled by a drill rig (100), the holes of the drill plan being defined by positions of and / or distances between the holes. The method comprises: drilling at least one hole (401; 501) defined by the drill plan; measuring and storing drilling parameter data for at least one drilling parameter during drilling of the at least one hole of the drill plan; adjusting a spacing between holes of the drill plan that remain to be drilled based on the measured and stored drilling parameter data; and drilling at least one hole of the drill plan that remain to be drilled using the adjusted spacing between the holes of the drill plan. The disclosure also relates to a system and a drill rig.

Description

[0001] METHOD AND SYSTEM FOR ADJUSTING A DRILL PLAN

[0002] Technical Field

[0003] The disclosure relates to drilling of a rock surface according to a drill plan, and more specifically to a method for adjusting a drill plan. The disclosure also relates to a system for adjusting a drill plan, and a drilling rig comprising a system. Furthermore, the disclosure also relates to a corresponding computer program and computer- readable medium causing a computer to carry out the method.

[0004] Background

[0005] In the field of mining and construction, there is a constant ongoing process of improving efficiency, productivity, and safety. Full or partial automation, and / or remote control of various processes occurring in mining or construction may be carried out to achieve this. It is hence often desirable that at least part of the machines that are used in mining or construction can be driven more or less autonomously, i.e. without an operator being required to influence more or less of the control / operation. It may also be desired to remotely control the mining or construction machines, e.g. by utilization of so-called tele-remote drilling control. In this way the operator may largely stay away from high-risk zones, where, e.g., drilling and blasting may take place.

[0006] Rock / ore excavation often involves drilling of a set of holes comprised in the mining or construction site, which may then be filled with explosive material that is detonated following the drilling of the holes. After the explosion, the broken material is transported away and processed, e.g., for mineral extraction.

[0007] The drilling may be carried out according to a drill plan, also called drill pattern, which is generated prior to commencing the drilling. The drill plan is a scheme, which comprises parameters such as, for example, a number of holes to be drilled, a spacing between the holes, and the positions of the holes. The drill plan is sent to the one or more drill rigs that are assigned for executing the drilling according to the drill plan, possibly by autonomous or remotely controlled drilling.

[0008] Summary It is an object of the disclosure to provide a method for adjusting a drill plan that may take into account differences in actual rock properties of the rock being drilled in relation to expected rock properties.

[0009] According to an aspect of the disclosure it is provided a method performed by a control arrangement for adjusting a drill plan, the drill plan defining a plurality of holes to be drilled by a drill rig, the holes of the drill plan being defined by positions of and / or distances between the holes, the method comprising: drilling at least one hole defined by the drill plan; measuring and storing drilling parameter data for at least one drilling parameter during drilling of the at least one hole of the drill plan; adjusting a spacing between holes of the drill plan that remain to be drilled based on the measured and stored drilling parameter data; and drilling at least one hole of the drill plan that remain to be drilled using the adjusted spacing between the holes of the drill plan.

[0010] As was mentioned, in general, when a rock surface is to be drilled for subsequent blasting a drill plan is generated prior to commencing drilling. The drill plan defines the holes to be drilled for a particular surface that subsequently is to be blasted, where the holes may be defined by their location on the surface to be drilled, and direction, e.g., inclination in relation to a reference. In particular, a drill plan may define the diameter of the holes to be drilled and, especially, the spacing between the holes to be drilled.

[0011] The drill plan is, in general, generated with an aim to obtain a desired fragmentation of the rock being drilled following blasting. That is, there may exist requirements regarding the resulting rock fragmentation of the broken rock. In case drill hole spacing is too low in relation to the prevailing hardness of the rock, and / or the amount of explosives being charged in the drill holes is excessive, the resulting blasting may result in a rock fragmentation where smaller fragments than expected is obtained. Hence, in this case an excess of explosives is used, with associated costs both for the excess explosives and improper rock fragmentation as a result.

[0012] Conversely, in case drill hole spacing is too large, and / or the use of explosives when charging the drilled holes is insufficient, the resulting blasting may give rise to oversized rock fragments that, in turn, may require additional blasting or other means for further breaking the rock. Such additional handling of the rock fragments may be both dangerous and associated with undesired consumption of time and cost for the further fragmentation.

[0013] In general, when generating a drill plan of this kind, there exist a general overall knowledge of the rock properties of the rock to be drilled. This knowledge, however, is inherently relatively coarse, and may be based on prospective drilling, where a larger geographical area may have been analyzed through drill holes that may have been drilled hundreds of meters, or more, apart. The rock properties may then be estimated from such drilling data, e.g., through extrapolation, where properties may vary from one drilled hole to another.

[0014] The rock properties for a rock surface to be drilled may, at least for a specific drill plan, be assumed to be essentially constant, and this will as a consequence have the result that a constant drill hole spacing will also be utilized in the generation of the drill plan. In case the rock that is being drilled in reality differs from the assumed rock properties, drawbacks such as those described above may result.

[0015] One method for alleviating problems of this kind may be to perform measurements while drilling the holes of the drill plan in order to log such measurements, denoted measurements while drilling data (MWD), for subsequent processing and use. For example, following drilling and blasting of a drill plan, the measurements while drilling data (MWD) may be utilized to adjust the expected rock properties of a subsequent surface to be drilled and hence be used in the generation of the drill plan for the subsequent surface to be drilled and blasted.

[0016] Measurements while drilling data (MWD) of this kind may also be used to compensate for differences in actual rock properties in relation to the expected rock properties prior to blasting by individually adapting the amount of explosives being charged in each hole. Such adaption of explosives may compensate for differences in rock properties and reduce the risk of insufficient, or excessive, fragmentation, but at the expense of a considerably more complicated and, as a consequence, timeconsuming step of charging the explosives. According to the disclosure it is provided in an alternative method for enhancing the result following blasting by adapting the drill plan as the drilling of the drill plan is ongoing.

[0017] Initially, the drill plan that has been generated prior to drilling is commenced is sent to the one or more drill rigs that are tasked with the drilling of the holes of the drill plan, such that they can commence executing of the drill plan, e.g. autonomously. The drill plan may also be sent to an operator station in case the one or more drill rigs are remotely controlled in the execution of the drill plan. The method according to the disclosure comprises to drill at least one hole as defined by the drill plan, and drilling parameter data for at least one drilling parameter is measured and stored during the drilling of the at least one hole of the drill plan. The measured and stored drilling parameter data is then used to adjusting a spacing between holes of the drill plan that remain to be drilled following the drilling of the at least one hole. The adjustment is based on the measured and stored drilling parameter data. In this way adjustments can be made to a drill plan as drilling of the drill plan is in progress to account for variations in rock properties in relation to expected rock properties. Following the adjustment of the spacing at least one hole of the drill plan that remain to be drilled is drilled using the adjusted spacing between the holes of the drill plan.

[0018] In this way, drill hole spacing of a drill plan can be adjusted when drilling has commenced in situations where the rock properties deviate from the expected rock properties. Thereby the resulting fragmentation of the rock following charging and blasting with a predetermined amount of explosives may more likely correspond to the expected fragmentation than would be the case if the complete drill plan was drilled according to the predetermined hole spacing. The disclosure may thereby make excavation more cost and time efficient.

[0019] According to aspects of the disclosure, the drill plan comprises drilling and blasting of a drill bench having a free face exhibiting a height and a crest, where the distance between holes parallel to the crest oftentimes is denoted spacing, and the distance between holes in a direction away from the crest, along the depth of the drill bench from the crest oftentimes is denoted burden. It is to be understood that the term spacing is used in the present disclosure to denote any spacing between holes of a drill plan, including burden. According to aspects of the disclosure, the method further comprises to drill a plurality of the holes of the drill plan, and measure and store drilling parameter data during the drilling of the plurality of holes of the drill plan. The spacing between holes of the drill plan that remain to be drilled may then be adjusted based on drilling parameter data measured and stored during the drilling of the plurality of drilled holes.

[0020] This may be used to obtain a more reliable estimation of the properties of the rock being drilled, e.g., in case the drilling of the first hole of the drill plan indicates a large deviation in relation to the expected rock properties.

[0021] According to aspects of the disclosure, the method comprises to drill at least one additional hole of the drill plan that remain to be drilled when the spacing between remaining holes to be drilled of the drill plan has been adjusted. The spacing of the holes of the drill plan that remain to be drilled may then be further adjusted based on drilling parameter data measured and stored during the drilling of the at least one additional hole of the drill plan. In this way the drill plan may be continuously updated as drilling of the holes of the drill plan progress.

[0022] According to aspects of the disclosure, the method further comprises to utilize the measured and stored drilling parameter data to estimate a measure of the hardness of the rock of the at least one drilled hole; and adjust the spacing between holes of the drill plan that remaining to be drilled based on the estimated hardness of the rock.

[0023] The estimation of the hardness of the rock may provide a good representation of the rock properties being drilled.

[0024] According to aspects of the disclosure, the drill plan is generated prior to commencing drilling, and may be based on a pre-estimated hardness of the rock to be drilled. The spacing between holes of the drill plan that remain to be drilled may be adjusted based on a difference between the pre-estimated hardness of the rock and the estimated the hardness of the rock. This may provide for an efficient way of adjusting the drill plan based on the difference between expected and actual conditions. The actual estimated rock hardness may hence be compared with a preestimated hardness to determine whether the drill plan is to be recalculated. According to aspects of the disclosure, the at least one drilling parameter that is measured and stored during drilling comprises one or more from: feed force, percussion pressure, torque on drill bit, accelerometer and / or gyro data measuring drill bit motion of a drill bit being used to carry out the drilling, consumed drilling energy. Hence various different alternatives regarding parameters that may be measured and stored and utilized in the adjusting of the drill plan.

[0025] According to aspects of the disclosure, a rock hardness is estimated based on the measured and stored drilling parameter data, and it is further determined whether the estimated rock hardness differs from a pre-estimated rock hardness by more than a predetermined difference. When this is the case the method may comprise to drill at least one additional hole prior to adjusting the spacing between remaining drill holes of the drill plan to be drilled. In this way it may be ascertained that the rock hardness actually differs by the predetermined extent, which may be the case if more than one hole indicates this. If, on the other hand, the hardness of the next drilled hole does not differ to the predetermined extent, the drill plan may be adjusted based on the second drilled hole, or alternatively one or more further holes may be drilled to form basis for the adjusting of the drill plan.

[0026] According to aspects of the disclosure, the method further comprises, following drilling of a hole of the drill plan, determining whether the spacing of the drill plan is to be recalculated based on the measured and stored drilling parameter data, and recalculating the spacing of the holes of the drill plan remaining to be drilled when it is determined that the drill plan is to be recalculated. For example, it can be determined that the drill plan is only to be recalculated when a rock property deviates from an expected rock property to a predetermined extent.

[0027] According to aspects of the disclosure, the holes of the drill plan are configured to be charged with explosives for blasting following drilling, which is in general the case. The method may comprise to recalculate the spacing between the holes of the drill plan that remain to be drilled in dependence of a predetermined volume of explosives to be charged, and the drill hole spacing may determined for the same amount of explosives to be charged in each drill hole. Hence, the recalculation of the drill plan can be carried out such that a same amount of explosives can always be used, which facilitates the charging process. According to aspects of the disclosure, the adjusting of the spacing between holes of the drill plan that remain to be drilled can be recalculated a plurality of times during drilling of the holes according to the drill plan based on the measured and stored drilling parameter data. Hence the drill plan can be continuously adapted to prevailing conditions.

[0028] According to aspects of the disclosure, the adjusting the spacing between holes that remain to be drilled comprises to increase the spacing between drill holes of the drill plan that remain to be drilled when the measured drilling parameter data indicates a hardness of the rock being softer than a pre-estimated hardness of the rock. Hence the number of holes of the drill plan can be reduced when the rock is softer than expected. Similarly, the spacing between drill holes of the drill plan remaining to be drilled can be reduced when the measured drilling parameter data indicates a hardness of the rock being harder than the pre-estimated hardness of the rock. Hence, the of holes of the drill plan can be increased when the rock is harder than expected.

[0029] According to aspects of the disclosure, the method comprises to, adjust, in addition, the inclination of holes of the drill plan that remain to be drilled, so as to adjust, in addition, hole spacing along the depth of the holes. In this way the drill plan can account for differences in rock properties along the depth of the holes.

[0030] According to a further aspect of the disclosure, the above mentioned and other objectives are achieved with a system for adjusting the spacing between remaining holes to be drilled, the system being configured to perform the described method.

[0031] The system according to this aspect can be extended into aspects corresponding to the aspects of the method according to the first aspect. Hence, an aspect of the system comprises the feature(s) of the corresponding aspect of the method.

[0032] It will be appreciated that all the embodiments described for the method aspects of the disclosure are applicable also to system aspects of the disclosure. Thus, all the aspects described for methods according to the disclosure may be performed by the system. The system and its embodiments have advantages corresponding to the advantages discussed above with regard to the various aspects of methods according to the disclosure. This also applies to the drill rig aspect of the disclosure, since the drill rig comprises a system according to the disclosure.

[0033] Further characteristics of aspects of the disclosure and advantages thereof are indicated in the detailed description of exemplary embodiments set out below and the attached drawings.

[0034] Brief Description of the Drawings

[0035] Fig. 1 schematically illustrates an exemplary drill rig which may be utilized to drill holes of to a drill plan determined according to aspects of the disclosure;

[0036] Fig. 2 schematically illustrates an exemplary drill bench;

[0037] Fig. 3 schematically illustrates an exemplary method according to aspects of the invention;

[0038] Fig. 4 schematically illustrates an exemplary adjusted drill pattern according to aspects of the disclosure;

[0039] Fig. 5 schematically illustrates another exemplary adjusted drill pattern according to aspects of the disclosure.

[0040] Detailed Description

[0041] Aspects of the present disclosure will be exemplified in the following in view of a particular example of a drill rig. The disclosure is, however, applicable for all kinds of drill rigs that are utilized in drilling of holes according to a drill plan.

[0042] Drilling of holes according to the examples discussed in the following may be arranged to be carried out by a single drill rig, or a fleet of, i.e. a plurality of, drill rigs that may be arranged to operate autonomously and concurrently within a shared area of, e.g., an open-pit mine. Rock / ore excavation in mines of this kind often involves drilling of a set of drill holes at predetermined positions in a work area, oftentimes denoted drill bench. The blast holes are then filled with explosive material that is detonated after all targets have been drilled. After the explosion, the broken material is taken away and processed, where the processing may depend on the reason for excavation. For example, the broken material may be processed for mineral extraction.

[0043] An example of a drill bench 200 is shown in Fig. 2, and will be described further below following a description of Fig. 1 , which schematically illustrates an exemplary side view of a drill rig 100 operating on a surface 130 which may be utilized in a solution according to embodiments of the invention for drilling holes of a bench according to Fig. 2. The drill rig 100 is only exemplary, and there exist various kinds of drill rigs of various designs that may alternatively be used according to the invention. The drill rig 100 constitutes a surface drill rig being used to drill vertical or inclined, substantially vertical holes using a drill tool attached to a drilling machine via a drill string. The drilling machine is slidably arranged along a feed beam. These elements are very common and therefore not explicitly disclosed. Instead, these elements are represented by a drill tower 101 and a schematically indicated drill string 110 indicating ongoing drilling of a hole 103. A drill bit 111 is attached to the end of the drill string. The general technology used when drilling using a drill rig according to Fig. 1 is well known per se. Drill rigs may also comprise a dust guard 104 to reduce dust from unnecessary spreading to ambient air and surrounding ground during drilling.

[0044] The drill rig 100 further comprises crawlers, or wheels as the case may be, 105 to allow the drill rig 100 to be moved from one position to another, such as from a hole that has been drilled to a hole that is about to be drilled.

[0045] The drill rig 100 also comprises a control system comprising at least one control unit 120, which controls various of the functions of the drill rig 100 and in particular drilling using the drill rig and possibly adjustment of drill plans according to embodiments of the invention. The control unit 120 can be arranged to control crawlers, drilling machine etc. by suitable control of various actuators such as cylinders / motors / pumps, valves etc. These are exemplified by actuators 107, 108. It is to be noted that there may be a number of actuators at various different locations on the drill rig. Drill rigs of the disclosed kind may also comprise more than one control unit, where each control unit, respectively, may be arranged to be responsible for various different functions of the drill rig. The control system of the drill rig 100, according to the present example, may also comprise transceiver means 109 for communication, e.g., with a remote location. For example, the drill rig 100 may be configured to receive control commands relating to crawlers, drill tower 101 , drilling machine etc. to carry out the received instructions, and also, e.g., a drill plan comprising holes to be drilled. The drill rig may also be configured to communicate various data to the remote location, such as measurement while drilling data (MWD) during ongoing drilling. The calculations performed when adjusting the drill plan according to the disclosure may be configured to be carried out, e.g., by the control unit 120 or any other suitable control unit onboard the drill rig. Alternatively the calculations may be configured to be carried out by computing means such as a computer at the remote location based on real time drilling parameter data being received from the drill rig 100.

[0046] As was mentioned, Fig. 2 illustrates a drill bench 200, where a plurality of holes 230, indicated by circles, are to be drilled for subsequent blasting. The geographical area making up the bench 200 is schematically outlined by an outer boundary indicated by solid lines, which may indicate a sub-portion of a larger bench that is to be drilled and blasted, and where the drilling and blasting may be carried out in rounds, where each round comprises its own drill plan for drilling a part of the overall area to be drilled. The drill bench is elevated in relation to an excavation floor 204, e.g. due to previous portions of the drill bench being drilled and blasted away. The drill plan is located along a crest 205 that has been formed, e.g., following previous blasting, and the subsequent blasting following drilling of the drill plan 100 will result in a new crest being formed in the back of the drill plan, indicated by dotted line 206. The reference numeral 207 indicates the free rock face, i.e. the inclined surface between the excavation floor 204 and the crest 205. Depending on the rock face angle (inclination) the so-called toe 208 may be larger or smaller, which may be taken into account when planning the drill plan, and in particular when positioning the holes closest to the crest 205, and thereby distance to the crest 205.

[0047] Fig. 2 also shows a drill rig 100 being used to drill the bench 200, where the drill rig 100 currently is drilling a first hole 201 of a drill plan. The drill plan is indicated by dashed lines 202 comprising the holes 203 and start hole 201 . The drill plan 202 may comprise, among other parameters, the number of holes to be drilled, the spacing 210, 211 between these holes, possibly in multiple directions, as is illustrated in the figure, and the positions of each one of the holes 201 , 203 to be drilled, where hole 201 hence represents the hole currently being drilled. Fig. 2 illustrates a single drill rig 100, but two or more drill rigs may be utilized to drill the holes of the drill plan 202. In the figure, hole spacing 210 represents the distance between holes of the drill plan in a direction essentially parallel with the crest. The drill hole spacing in this direction may also be denoted drill spacing. Furthermore, hole spacing 211 represents the distance between the holes in the direction away from the crest where the hole spacing in this direction may also be denoted drilled burden. However, as was mentioned, spacing is used herein to denote any spacing between holes.

[0048] As was mentioned above, there exist a general desire in mining and excavation to reduce the cost and energy being used to blast rock into a desired size of smaller rocks in order to facilitate extraction of ore from the rock. The right degree of fragmentation (i.e. resulting size of the broken rocks) is critical to allow for efficiently removing the ore from the rocks. In case the resulting fragments are too big more energy is required to process the broken rock, and this also slows down the overall processing efficiency. Conversely, in case the fragmentation results in too fine particles this can also slow the processing of the ore. Incorrect fragmentation may affect the throughput of a processing facility substantially, e.g., in the order up to 50%.

[0049] The object of the drill plan, and hence selection of hole diameter and hole spacing, is to as much as possible achieve such fragmentation. In general the drill plan is designed with a fixed hole diameter, drill burden and drill spacing based on a predrilled understanding of rock hardness and fracturability. The combination of hole diameter, hole length, burden and spacing defines the total volume of explosive that is to be used to blast the rock.

[0050] The pre-drilled understanding of rock hardness and fracturability in general comes from exploration data. As was mentioned above, such exploration information, however, is not very granular. For example, it is common to drill exploration holes at distances, e.g., in the order of 500 meter intervals. In contrast, most drill benches are much smaller, for example spanning over 100-200 meters. This means that the actual hardness of a drill bench may not be well known until the actual production drilling is finished.

[0051] Once drilling of a drill plan is finished, Measure While Drilling data (MWD) can be created, and this data can be used to determine the actual hardness of the rock that has been drilled. In general, harder rock needs more power to fragmentise, softer rock needs less power. Once the drilling of a drill plan has finished, the only way to adjust blasting energy per hole for an already drilled hole is to adjust the explosive density when loading the drilled holes with explosives prior to blasting. Although this may be carried out in some mining operations, it is not general practice, and it also requires computerized explosive charging equipment that interfaces with the MWD data to deliver the optimum amount of energy per hole and possibly even change the explosive density in the hole length. Even though such a procedure may reduce the total amount of explosives used in the blasting of the drill bench, and the fragmentation of the rock may be improved, this is not only complicated but also time consuming. In addition an excess number of holes may still be drilled.

[0052] According to the disclosure, it is provided a solution that may both improve fragmentation of the rock, as well as reduce amount of explosives being used to prevent over-fragmentation, and that may also reduce the number of holes being drilled when rock is softer than expected.

[0053] An exemplary method according to the disclosure is illustrated in Fig. 3. The method 300 starts in step 310, where a first hole of a drill plan is drilled. Hence, a drill plan may be generated, e.g., according to any method that has been used in the prior art and, for example, be generated based on geological survey data as exemplified above. The thus generated drill plan may be downloaded to the drill rig and drilling be commenced by drilling a first hole of the drill plan, such as, for example, hole 201 in Fig. 2.

[0054] In step 320, while drilling of hole 201 is ongoing, drilling parameter data is collected and stored. Various types of drilling parameter data may be measured during the drilling of the hole 201 . For example, the drilling parameter data may comprise one or more from: feed force; percussion pressure; torque on drill bit; accelerometer data and / or gyro data measuring drill bit motion of a drill bit being used to carry out the drilling; consumed drilling energy; where one or more of these measured parameters may be utilized to estimate, e.g., a hardness of the rock.

[0055] Following drilling of hole 201 , or even during drilling of the hole 201 , the measured and stored drilling parameter data is used to analyze the rock that is currently being drilled, and if the data discloses that rock properties deviates from the rock properties that have been estimated using the survey data, the drill plan that is currently being drilled is recalculated to adjust the spacing between the holes of the drill plan, step 330.

[0056] With regard to the rock properties, for example, the measured and stored drilling parameter data may be utilized to estimate a measure of the hardness of the rock of the at least one drilled hole that has been drilled or is being drilled. This estimate may be used in the determination whether the spacing between the holes of the drill plan is to be adjusted.

[0057] For example, the spacing between drill holes of the drill plan that remain to be drilled may be increased when the measured drilling parameter data indicates a hardness of the rock being softer than a pre-estimated hardness of the rock. Alternatively, or in addition, the spacing between drill holes of the drill plan remaining to be drilled may be decreased when the measured drilling parameter data indicates a hardness of the rock being harder than the pre-estimated hardness of the rock.

[0058] A subsequent hole of the drill plan may then be drilled, step 340, where the spacing between the holes have been adjusted, when required, in relation to the original drill plan. This is exemplified in Fig. 4, which shows a figure similar to Fig. 2, but where it has been determined, in step 330, during and / or following drilling of a first hole 401 of the drill plan, that the properties of the rock deviates from the expected properties in such a way that the original drill plan hole spacing is determined to be too tight and that, in fact, the holes should be drilled more spaced apart in order to obtain a desired fragmentation of the rock following blasting. This is illustrated by newly calculated drill plan illustrated by dotted holes 403, where the hole spacing 410, 411 hole spacing has been increased in relation to the hole spacing 210, 211 of the original drill plan, which is also indicated in the figure.

[0059] A further example is illustrated in figure 5, where, following drilling a first hole 501 of the drill plan it is determined that the properties of the rock deviates from the expected rock properties in such a way that the original drill plan hole spacing instead is determined to be too sparse, and that the drilled holes of the drill plan should be more closely located to each other. This is illustrated by drill hole spacing 510, 511 for the dotted holes 503 of the newly calculated drill plan, where the drill hole spacing 510, 511 is smaller than drill hole spacing 210, 211.

[0060] The disclosure hence provides for a solution where the hole spacing can be adapted to the actually prevailing rock conditions, where the rock conditions may be determined when the drilling of the drill plan has commenced, e.g., during or following drilling of the first hole of the drill plan so that the complete the drill bench need not be drilled prior to carrying out adjustments to account for actual conditions. This will facilitate subsequent blasting, e.g., since the adjusted hole spacing during the drilling of the drill plan may allow the same predetermined amount of the explosives to be charged in each drilled hole while still providing that the desired fragmentation is obtained. It is furthermore to be noted that the recalculation of the drill plan may take into account an intended amount of explosives to be used, so that the spacing of the drill holes can be adapted accordingly. For example, in case a specific amount of explosives is to be used a drill plan comprising more sparsely located holes may be calculated, and vice versa.

[0061] According to aspects of the disclosure, instead of drilling a single hole prior to recalculating the drill plan, two or more holes may be drilled prior to adjusting the spacing between the holes of the drill plan that remain to be drilled. Drilling parameter data may then be measured and stored for these two or more holes, and the calculations for adjusting the spacing between the holes may be carried out based on data from more than one drilled hole prior to actually adjusting the spacing.

[0062] For example, a rock hardness may be estimated based on the measured and stored drilling parameter data, where this estimation may be carried out during or following the drilling of the first hole. It may then be determined whether this estimated rock hardness differs from a pre-estimated rock hardness by more than a predetermined difference. The pre-estimated rock hardness may be a rock hardness estimated using survey data, or using data generated during drilling of a previous bench. In case the rock hardness estimated using data obtained during drilling of the first hole of the drill plan then differs by more than the predetermined difference, according to aspects of the disclosure, at least one second hole may be drilled prior to actually changing the spacing between holes to be drilled. This may be carried out, for example, in order to ensure that the rock hardness actually does deviate to the predetermined extent, and not only locally at the location of the first hole being drilled.

[0063] When the hole spacing has been adjusted for the remaining holes to be drilled of the drill plan, following the drilling of one or more holes according to the above, the drilling may commence by drilling at least one additional hole of the drill plan that remain to be drilled. Similar to the above, the drill hole spacing may again be recalculated based on the new drilling parameter data that has been obtained during the drilling of the subsequent hole, in case this is determined to be necessary.

[0064] Hence, in principle, the drill hole spacing may be recalculated each time a new hole is drilled.

[0065] According to aspects of the disclosure, the hole spacing of the drill plan is calculated such that the holes are configured to be charged with a same amount of explosives for blasting following drilling, and the recalculation of the spacing between the holes of the drill plan that remain to be drilled may also be calculated such that the same predetermined volume of explosives are to be charged in the holes of the drill plan.

[0066] These calculations may utilize, e.g., prestored values for various amounts of explosives to be used for various different rock properties, and also for different hole spacings. Also, the calculations may be configured to depend on the desired degree of fragmentation, where higher amounts of explosives, and / or lower hole spacings may be used when finer fragmentation is desired, and vice versa, where hence the solution according to the disclosure is utilized to adjust the drill plan to maintain the desired fragmentation.

[0067] So far, the adjusting of the drill plan has been discussed in relation to the distances between the holes at the surface, such as the surface of the drill bench, when adjusting the hole spacing of the drill plan. According to aspects of the disclosure, the hole spacing may be adjusted in addition in terms of the inter-hole distance between holes along the depth of the hole. The holes hence need not be drilled in parallel, but may be drilled at different inclinations in relation to each other, and these inclinations may be adjusted, e.g., in case the properties of the rock change along the depth of the holes. In case the drilling indicates an area with harder or softer rock at some depth, the inclinations of the holes remaining to be drilled may also be adjusted such that the holes are comparatively closer or further apart at such locations. Hence hole spacing may also be adjusted along the depth of the holes. It is also possible to add or remove holes from the drill plan in this regard.

[0068] It is to be noted that drill spacing is used to represent the distance between holes of a drill plan in any direction, and hence also e.g. to represent the distances between holes where separate terms are used in the art, such as drill burden and crest burden. Finally, it should be understood that the disclosure is not limited to the aspects described above, but also relates to and incorporates all aspects within the scope of the appended independent claims.

Claims

CLAIMS1 . A method (300) performed by a control arrangement for adjusting a drill plan, the drill plan defining a plurality of holes to be drilled by a drill rig (100), the holes of the drill plan being defined by positions of and / or distances between the holes, the method comprising: drilling at least one hole (401 ; 501 ) defined by the drill plan; measuring and storing drilling parameter data for at least one drilling parameter during drilling of the at least one hole of the drill plan; adjusting a spacing between holes of the drill plan that remain to be drilled based on the measured and stored drilling parameter data; and drilling at least one hole of the drill plan that remain to be drilled using the adjusted spacing between the holes of the drill plan.

2. The method (300) according to claim 1 , further comprising: drilling a plurality of the holes of the drill plan; measuring and storing drilling parameter data during drilling of the plurality of holes of the drill plan; and adjusting the spacing between holes of the drill plan that remain to be drilled based on drilling parameter data measured and stored during the drilling of the plurality of drilled holes.

3. The method (300) according to claim 1 or 2, comprising, when the spacing between remaining holes to be drilled of the drill plan has been adjusted: drilling at least one additional hole of the drill plan that remain to be drilled; and further adjusting the spacing of holes of the drill plan that remain to be drilled based on drilling parameter data measured and stored during the drilling of the at least one additional hole of the drill plan.

4. The method (300) according to any one of the claims 1 -3, further comprising: utilizing the measured and stored drilling parameter data to estimate a measure of the hardness of the rock of the at least one drilled hole; and adjusting the spacing between holes of the drill plan that remaining to be drilled based on the estimated hardness of the rock.

5. The method (300) according to claim 4, further comprising: generating the drill plan prior to commencing drilling, the drill plan being generated based on a pre-estimated hardness of the rock to be drilled, and adjusting the spacing between holes of the drill plan that remain to be drilled based on a difference between the pre-estimated hardness of the rock and the estimated the hardness of the rock.

6. The method (300) according to any one of the claims 1 -5, wherein the at least one drilling parameter comprises one or more from: feed force, percussion pressure, torque on drill bit, accelerometer and / or gyro data measuring drill bit motion of a drill bit being used to carry out the drilling, consumed drilling energy.

7. The method (300) according to any one of the claims 1 -6, further comprising: estimating a rock hardness based on the measured and stored drilling parameter data; determining whether the estimated rock hardness differs from a pre-estimated rock hardness by more than a predetermined difference; and drilling at least one additional hole prior to adjusting spacing between remaining drill holes of the drill plan to be drilled when the estimated rock hardness differs from the pre-estimated rock hardness by more than the predetermined difference.

8. The method (300) according to any one of the claims 1 -7, further comprising, following drilling of a hole of the drill plan: determining whether the spacing of the drill plan is to be recalculated based on the measured and stored drilling parameter data, and recalculating the spacing of the holes of the drill plan remaining to be drilled when it is determined that the drill plan is to be recalculated.

9. The method (300) according to any one of the claims 1-8, the holes of the drill plan being configured to be charged with explosives for blasting following drilling, further comprising: recalculating the spacing between the holes of the drill plan that remain to be drilled in dependence of a predetermined volume of explosives to be charged,wherein drill hole spacing is determined for the same amount of explosives to be charged in each drill hole.

10. The method (300) according to any one of claims 1-9, wherein the adjusting of the spacing between holes of the drill plan that remain to be drilled is recalculated a plurality of times during drilling of the holes according to the drill plan based on the measured and stored drilling parameter data.11 . The method (300) according to any one of the claims 1 -10, further comprising, when adjusting the spacing between holes remaining to be drilled: increasing the spacing between drill holes of the drill plan that remain to be drilled when the measured drilling parameter data indicates a hardness of the rock being softer than a pre-estimated hardness of the rock; and / or decreasing the spacing between drill holes of the drill plan remaining to be drilled when the measured drilling parameter data indicates a hardness of the rock being harder than the pre-estimated hardness of the rock.

12. The method (300) according to any one of the claims 1 -11 , further comprising, when adjusting the drill plan: reducing the number of holes of the drill plan when the when the measured drilling parameter data indicates a hardness of the rock being softer than a preestimated hardness of the rock, and / or increasing the number of holes of the drill plan when the measured drilling parameter data indicates a hardness of the rock being harder than the pre-estimated hardness of the rock.

13. The method (300) according to any one of the claims 1 -12, further comprising: when adjusting the hole spacing of the drill plan, adjusting, in addition, the inclination of holes of the drill plan that remain to be drilled, so as to adjust, in addition, hole spacing along the depth of the holes.

14. Computer program comprising instructions which, when the program is executed by a computer, cause the computer to carry out the method according to any one of the claims 1 -13.

15. Computer-readable medium () comprising instructions which, when executed by a computer, cause the computer to carry out the method according to any one of the claims 1 -13.

16. A system for adjusting a drill plan, the drill plan defining a plurality of holes to be drilled by a drill rig (100), the holes of the drill plan being defined by positions of and / or distances between the holes, the system comprising: drilling means for drilling at least one hole defined by the drill plan; measuring means for measuring and storing drilling parameter data for at least one drilling parameter during drilling of the at least one hole of the drill plan; adjusting means for adjusting a spacing between holes of the drill plan that remain to be drilled based on the measured and stored drilling parameter data.

17. A drilling rig (100) comprising the system for adjusting a drill plan according to claim 16.

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