Drill bit breakout assembly

Abstract

Provided is a drill bit breakout assembly (22) for a mobile drill rig (20), the assembly (22) comprising a deck assembly (24) comprising an upper plate (26) separated from a lower plate (28) via a plurality of spacers (30) of predetermined dimensions. Each plate (26) and (28) defines a drill rod aperture (32) therethrough, the deck assembly (24) configured to be operatively interspaced within a mast (18) of the mobile drill rig (20) so that a drill rod (34) is able to pass unrestricted via these drill rod apertures (32). The deck assembly (24) further defines a receptacle (36). Drill bit breakout assembly (22) also includes a breakout plate (38) defining a drill bit aperture (40) shaped and dimensioned to receive a drill bit therethrough and defining peripheral protrusions (44) configured to engage an irregular profile of the drill bit to arrest rotation thereof. In this manner, the breakout plate (38) is slidably receivable within the receptacle (36) of the deck assembly (24) to facilitate in situ breakout of the drill bit when the drill bit (42) is engaged therein.

Description

DRILL BIT BREAKOUT ASSEMBLYTECHNICAL FIELD

[0001] This invention relates broadly to the field of drilling, and more speci fically to a drill bit breakout assembly for a mobile drill rig, an associated mobile drill rig comprising such a drill bit breakout assembly, and a method for breaking-out a drill bit from a mobile drill rig .BACKGROUND ART

[0002] The following discussion of the background art is intended to facilitate an understanding of the present invention only . The discussion is not an acknowledgement or admission that any of the material referred to is or was part of the common general knowledge as at the priority date of the application .

[0003] In surface mining, down-the-hole or DTH drilling is often used as part of drilling and blasting techniques , which is the controlled use of explosives to break rock for excavation . In down-the-hole dri lling, a drill rod is fitted with a hammer at its lower end, and the hammer operates with the drill bit screwed into the end of the hammer . The hammer is typically activated through the addition of compressed air and drilled into the ground - simultaneously rotating and impacting . A flushing fluid current collects the loosened drill cuttings and conveys them upwards and out of the drilled hole .

[0004] DTH drilling is often used as part of drill-and-blast surface mining practices , where a bench of an ore body is drilled with a plurality of blast holes , which are subsequently charged with explosives and detonated to remove material as part of the mining process . Mobile drill rigs are generally used for this drilling process across the bench .

[0005] Mobile drill rigs 20 , such as the Epiroc™ D65™ shown for background in Figures 1A and IB , generally comprise a mobile platform, such as a tracked platform 11 , with a boom 6 mounted thereon and supporting a mast 18 which includes a drive unit , feeder 7 and a rod handling system 8 for drilling into a surface , such as the ground . Such conventional mobile drill rigs typically include a rod guide 10 at a bottom of said mast 18 , as shown .

[0006] In contrast with larger drill rigs and platforms , with many mobile drill rigs , the opening in the rod guide 10 ( or rotary table on larger rigs ) is too small to allow the drill bit to pass therethrough, making it necessary to attach or detach the drill bit to or from the lower end of the drill string, respectively, at a point below the rod guide 10 . Typically, as part of the drilling process , the drill bit is rotated along a threading direction thereof on the drill pipe so that the bit does not unthread or unscrew during drilling . As part of the drilling process , drill bits wear out , which requires periodic replacement . However, given the threaded connection to secure the drill bit to the drill string, the drill bit can become very tightly threaded onto the drill pipe or string during the drilling process , making such replacement di f ficult .

[0007] As a result , in order to detach the drill bit from the drill pipe or string, a bit breakout table , bit breakout bench or breakout pot 17 is typically required in order to unthread the drill bit . Such conventional bit breakout also often involves a hydraulic-type bit breaker or clamp arrangement 9 which is mounted on the mast 18 of the drill rig 20 and configured to grip the drill pipe so that the drill bit can be unthreaded therefrom, typically manually via large wrenches , or via a second clamp arrangement able to turn with respect to the first clamp ( as shown in Figure IB ) , or the like . The bit breakout bench 17 ( also referred to asbreakout pot , basket or table ) is generally a separate frame or structure which i s typically placed on the ground in which the bit can be secured against rotation in order to unthread the drill pipe from the bit . Such a breakout table 17 is inherently of robust construction, such as a large metal framework, making it heavy and cumbersome .

[0008] Such conventional breakout practices are typically very labour-intensive and also potentially dangerous , as it requires manually moving heavy breakout tables , pots or frames to place the drill bit into , or using large wrenches to unthread the bit when clamped via a breakout clamp . Additionally, conventional breakout practices can often impede mining production due to lost time in order to replace worn-out drill bits , given the time and ef fort required for such conventional practices . Drill wrenches and / or breakout pots or frames must be employed, often requiring moving the mobile drill rig out of position, taking time and manual ef fort .

[0009] As a result , Applicant has identi fied shortcomings in the art or breaking-out drill bits from mobile drill rigs typically used as part of surface mining drill-and-blast practices and the current invention was conceived with these shortcomings in mind .SUMMARY OF THE INVENTION

[0010] The skilled addressee is to appreciate that reference herein to the term 'breakout ' broadly refers to a process of unthreading or unscrewing a drill bit from a drill rod or string, as known in the art of drilling . Additionally, reference herein to a 'mobile drill rig' generally comprises broad reference to any drill rig which is mounted on a mobile platform, such as a tracked or wheeled platform for moving the drill rig as necessary .

[0011] The skilled addressee will further appreciate that a drill bit used by a mobile drill rig for drilling generally comprises an irregular transaxial profile or transverse axial cross-section profile , i . e . a plane substantially perpendicular to a length of the drill bit . Additionally, reference herein to a 'drill rod' generally comprises broad and inclus ive reference to a drill rod with or without a down-the-hole or DTH hammer and a drill bit .

[0012] According to a first aspect of the invention there is provided a drill bit breakout assembly for a mobile drill rig, said assembly comprising : a deck assembly comprising an upper plate separated from a lower plate via a plurality of spacers of predetermined dimensions , each plate defining a drill rod aperture therethrough, said deck assembly configured to be operatively interspaced within a mast of said mobile drilling rig so that a drill rod is able to pass unrestricted via said drill rod apertures , the deck assembly further defining a receptacle ; and a breakout plate defining a drill bit aperture shaped and dimensioned to receive a drill bit therethrough, said drill bit aperture defining peripheral protrusions configured to engage an irregular profile of the drill bit to arrest rotation thereof ; wherein the breakout plate is slidably receivable within the receptacle of the deck assembly to facilitate in si tu breakout of the drill bit when the drill bit is engaged therein .

[0013] The skilled addressee is to appreciate that such in si tu breakout of the drill bit from the drill rod is generally performed by means of actuating a drive unit of the drill rig, i . e . rotation of the drill rod in order to unthread the drill bit engaged within the breakout plate . The existing breakout j aws of the drill rig are typically actuated and used to hold the drill rod or hammer when the drill bit is located in the breakout plate . The grippingand rotating action then works the bit against the peripheral protrusions of the breakout plate to complete the breakout action .

[0014] In an embodiment , the deck assembly comprises the upper plate separated from the lower plate so that the respective drill rod apertures are coaxial .

[0015] In an embodiment , the spacers of predetermined dimensions are mounted proximate the respective corners of each upper and lower plate .

[0016] In an embodiment , the spacers of predetermined dimensions are mounted proximate the respective corners of each upper and lower plate comprise cylinder-shaped spacers with fasteners , such as bolts , passing axially through each spacer and fast at each end with a respective plate .

[0017] In an embodiment , the spacers of predetermined dimensions comprise spacers laterally mounted on sides of the deck assembly and / or upper and lower plates , said lateral spacers shaped and dimensioned to facilitate the operative interspacing of the deck assembly within the mast of the mobile drilling rig .

[0018] In an embodiment , the predetermined dimensions of the spacers are selected to facilitate operative interspacing of the deck assembly within the mast of the mobile drilling rig .

[0019] In an embodiment , the drill rod apertures are substantially circular with a diameter larger than a largest diameter of the irregular profile of the drill bit .

[0020] In an embodiment , the deck assembly is operatively interspaced within the mast of the mobile drilling rig below a bit breakout clamp and a dust boot of said mast .

[0021] In an embodiment , the receptacle defined by the deck assembly comprises at least one pair of guiding lugs proj ecting from the deck assembly, said at least one pair of guiding lugs shaped and dimensioned to receive the breakout plate slidably therebetween .

[0022] In an embodiment , the at least one pair of guiding lugs proj ect downward from the lower plate .

[0023] In an embodiment , the breakout plate defines U-shaped grooves on opposite sides thereof , each groove configured to receive a guiding lug therein when the breakout plate is fully received within the receptacle .

[0024] In an embodiment, the peripheral protrusions defined about the drill bit aperture are complimentarily shaped and dimensioned to correspond to the irregular profile of the drill bit .

[0025] According to a second aspect of the invention there is provided a mobile drill rig having a mast comprising a drive unit for rotating a drill rod with a drill bit , the mobile drill rig comprising a dri ll bit breakout assembly interspaced within said mast , the drill bit breakout assembly comprising : a deck assembly comprised of an upper plate separated from a lower plate via a plurality of spacers of predetermined dimensions , each plate defining a drill rod aperture therethrough so that the drill rod is able to pass unrestricted via said drill rod apertures , the deck assembly further defining a receptacle ; and a breakout plate defining a drill bit aperture shaped and dimensioned to receive the drill bit therethrough, said drill bit aperture defining peripheral protrusions configured to engage an irregular profile of the drill bit to arrest rotation thereof ;wherein the breakout plate is slidably receivable within the receptacle of the deck assembly to facilitate in si tu breakout of the drill bit when the drill bit is engaged therein .

[0026] In an embodiment , the deck assembly comprises the upper plate separated from the lower plate so that the respective drill rod apertures are coaxial .

[0027] In an embodiment , the spacers of predetermined dimensions are mounted proximate the respective corners of each upper and lower plate .

[0028] In an embodiment , the spacers of predetermined dimensions mounted proximate the respective corners of each upper and lower plate comprise cylinder-shaped spacers with fasteners , such as bolts , passing axially through each spacer and fast at each end with a respective plate .

[0029] In an embodiment , the spacers of predetermined dimensions comprise spacers laterally mounted on sides of the deck assembly and / or upper and lower plates , said lateral spacers shaped and dimensioned to facilitate the operative interspacing of the deck assembly within the mast of the mobile drilling rig .

[0030] In an embodiment , the predetermined dimensions of the spacers are selected to facilitate operative interspacing of the deck assembly within the mast of the mobile drilling rig .

[0031] In an embodiment , the drill rod apertures are substantially circular with a diameter larger than a largest diameter of the irregular profile of the drill bit .

[0032] In an embodiment , the deck assembly is operatively interspaced within the mast of the mobile drilling rig below a bit breakout clamp and a dust boot of said mast .

[0033] In an embodiment , the receptacle defined by the deck assembly comprises at least one pair of guiding lugs proj ecting from the deck assembly, said at least one pair of guiding lugs shaped and dimensioned to receive the breakout plate slidably therebetween .

[0034] In an embodiment , the at least one pair of guiding lugs proj ect downward from the lower plate .

[0035] In an embodiment , the breakout plate defines U-shaped grooves on opposite sides thereof , each groove configured to receive a guiding lug therein when the breakout plate is fully received within the receptacle .

[0036] In an embodiment, the peripheral protrusions defined about the drill bit aperture are complimentarily shaped and dimensioned to correspond to the irregular profile of the drill bit .

[0037] According to a third aspect of the invention there is provided a method for breaking-out a drill bit from a mobile drill rig, said method comprising the steps of : providing a mobile drill rig in accordance with the second aspect of the invention; sliding, into the receptacle of the deck assembly, a breakout plate defining a drill bit aperture shaped and dimensioned to receive the drill bit therethrough, said drill bit aperture defining peripheral protrusions configured to engage an irregular profile of the drill bit to arrest rotation thereof ; andactivating a drive unit of the drill rig to rotate the drill rod to facilitate in si tu breakout of the drill bit engaged in the breakout plate .

[0038] In an embodiment , the method comprises the step of raising the drill rod with drill bit along the mast in order that the drill bit engages with the breakout plate within the deck assembly .

[0039] According to a further aspect of the invention there is provided a drill bit breakout assembly for a mobile drill rig, a mobile drill rig comprising such a drill bit breakout assembly, and a method for breaking-out a drill bit from a mobile drill rig, substantially as herein described and / or illustrated .BRIEF DESCRIPTION OF THE DRAWINGSThe description will be made with reference to the accompanying drawings in which :Figure 1A and B are diagrammatic representations of components of a conventional mobile drill rig, such as the Epiroc D65™;Figure 2 is a diagrammatic side-view representation of a drill bit breakout assembly when incorporated into a mast of a mobile drill rig, in accordance with an aspect of the present invention;Figure 3 is diagrammatic perspective-view representation of a drill bit breakout assembly for a mobile drill rig, in accordance with aspects of the present invention;Figure 4 is a diagrammatic perspective-view representation of the drill bit breakout assembly of Figure 3 , showing a drill bit passed through apertures of a deck assembly; andFigure 5 is a diagrammatic bottom-view representation of the drill bit breakout assembly of Figure 4 , showing an irregular profile of a drill bit engaged by peripheral protrusions of a breakout plate .DETAILED DESCRIPTION OF EMBODIMENTS

[0040] Further features of the present invention are more fully described in the following description of several non-limiting embodiments thereof . This description is included solely for the purposes of exempli fying the present invention to the skilled addressee . It should not be understood as a restriction on the broad summary, disclosure or description of the invention as set out above .

[0041] In the figures , incorporated to illustrate features of the example embodiment or embodiments , like reference numerals are used to identi fy like parts throughout . Additionally, features , mechanisms and aspects well-known and understood in the art will not be described in detail , as such features , mechanisms and aspects will be within the understanding of the skilled addressee .

[0042] Additionally, the accompanying figures do not represent engineering or design drawings , but provide a functional overview of the invention only . As a result , features and practical construction details required for various embodiments may not be indicated in each figure , but such construction requirements will be within the understanding of the skilled addressee .

[0043] Broadly, the present invention provides a drill bit breakout assembly 22 which finds particular application in facilitating bit breakout from mobile drill rigs , such as the Epiroc D65™ and related rigs , without requiring the use of largetools or breakout pots , or the use of breakout clamps or j aws , as breakout can be performed by using a drive unit of the mobile drill rig 20 to rotate the drill rod 34 in order to unthread of unscrew a drill bit 42 from said drill rod 34 .

[0044] With reference now to the accompanying figures , there is broadly exempli fied one possible embodiment of such a drill bit breakout assembly 22 for a mobile drill rig 20 . In this embodiment , the breakout assembly 22 comprises a deck assembly 24 and a breakout plate 38 . The deck assembly 24 comprises an upper plate 26 separated from a lower plate 28 via a plurality of spacers 30 of predetermined dimensions .

[0045] Each plate 26 and 28 defines a drill rod aperture 32 therethrough, as shown, with the deck assembly 24 configured to be operatively interspaced within a mast 18 of a mobile drill rig 20 so that a drill rod 34 is able to pass unrestricted via the drill rod apertures 32 in the respective plates 26 and 28 .

[0046] In one embodiment , the spacers of predetermined dimensions comprise spacers laterally mounted on sides of the deck assembly 24 and / or upper and lower plates 26 and 28 , said lateral spacers 30 shaped and dimensioned to facilitate the operative interspacing of the deck assembly 24 within the mast 18 of the mobile drill rig 20 . In one embodiment , the spacers 30 of predetermined dimensions are mounted proximate the respective corners of each upper and lower plate 26 and 28 and comprise cylinder-shaped spacers with fasteners , such as bolts , passing axially through each spacer and fast at each end with a respective plate 26 and 28 . Of course , variations hereon are possible and anticipated .

[0047] The skilled addressee will appreciate that the predetermined dimensions of the spacers 30 are typically selectedto facilitate operative interspacing of the deck assembly 24 within the mast 18 of the mobile drill rig 20 . For example , the amount of space available to the deck assembly 24 may depend on a configuration of the mast to allow proper operation of the mobile drill rig 20 , i . e . a smaller drill rig 20 may have less space available than a relatively larger drill rig 20 , or the like . As a result , di f ferent spacers 30 may be used to accommodate di f ferent mobile drill rigs 20 , as per requirements .

[0048] In one embodiment , the deck assembly 24 comprises the upper plate separated from the lower plate so that the respective drill rod apertures 32 are coaxial , i . e . one over the other when viewed from above or below . In one embodiment , the drill rod apertures 32 are substantially circular with a diameter larger than a largest diameter of the irregular profile of the drill bit 42 . In one embodiment , the deck assembly 24 is operatively interspaced within the mast of the mobile drilling rig below a bit breakout clamp and a dust boot of said mast .

[0049] The deck assembly 24 further defines a receptacle 36 , with the drill bit breakout assembly 22 including a breakout plate 38 that defines a drill bit aperture 40 which is shaped and dimensioned to receive a drill bit 42 therethrough . Importantly, the drill bit aperture 40 defines peripheral protrusions 44 that are configured to engage an irregular profile of the drill bit 42 to arrest rotation thereof . Such peripheral protrusions 44 may take a variety of forms , as will be appreciated by the skilled addressee . In one embodiment , the peripheral protrusions 44 defined about the drill bit aperture 40 are complimentarily shaped and dimensioned to correspond to the irregular profile of the drill bit 42 , as diagrammatically shown in Figure 5 .

[0050] In this manner, the breakout plate 38 is slidably receivable within the receptacle 36 of the deck assembly 24 inorder to facilitate in si tu breakout of the drill bit 42 when the drill bit 42 is engaged within the breakout plate 38 . As a result , the drill rig 20 is able to function conventionally with the drill rod 34 passing unhindered via the drill rod apertures 32 in the upper and lower plates 26 and 28 of the deck assembly 24 when the breakout plate 38 is not present .

[0051] When drill bit breakout is required, for example when replacing a dull bit with a new bit , the drill rod 34 may be raised along the mast and the breakout plate slid into the receptacle 36 of the deck assembly 24 . The drill rod 34 is then lowered until the drill bit 42 is captured within the drill bit aperture 40 of the breakout plate 38 , with the peripheral protrusions 44 preventing rotation of the drill bit 42 whilst allowing rotation of the drill rod via a drive unit of the drill rig 20 . The existing breakout j aws of the drill rig are typically actuated and used to hold the drill rod or hammer when the drill bit is located in the breakout plate , as described . The gripping and rotating action then works the bit against the peripheral protrusions 44 of the breakout plate to complete the breakout action .

[0052] In one embodiment , the receptacle 36 defined by the deck assembly 24 comprises at least one pair of guiding lugs 48 proj ecting from the deck assembly 24 , said at least one pair of guiding lugs 48 shaped and dimensioned to receive the breakout plate 38 slidably therebetween . In one embodiment , the at least one pair of guiding lugs 48 proj ect downward from the lower plate 28 , but of course variations hereon are possible and anticipated . For example , the receptacle 34 may be located between the plates 26 and 28 , above the upper plate 26 , etc .

[0053] In the exempli fied embodiment , the breakout plate 38 defines -shaped grooves 52 on opposite sides thereof , as shown inFigure 5 with each groove 52 configured to receive a guiding lug48 therein when the breakout plate 38 is fully received within the receptacle 36 in order to secure the breakout plate within the deck assembly 24 . Again, variations hereon are possible and anticipated and will be readily apparent to the skilled addressee .

[0054] In a speci fic example , the deck assembly 24 comprises upper and lower plates 26 and 28 manufactured from Bissalloy™ steel of 25mm thickness with a width of 400mm and a length of 388 mm . The guiding lugs 48 comprise 30 . 2mm cylindrical spacers of 40mm length held in place by 15mm bolts , with the U-shaped grooves 52 shaped accordingly .

[0055] The skilled addressee is to appreciate that the present invention includes an associated mobile drill rig 20 comprising such a drill bit breakout assembly 22 as described herein, as well as an associated method for breaking-out a drill bit 42 from a mobile drill rig 20 .

[0056] Such a method typically comprises the steps of providing a mobile drill rig 20 having the drill bit breakout assembly 22 incorporated within a mast 18 thereof . In one embodiment , the deck assembly 24 is incorporated between a dust boot 46 and breakout j aws 9 of the mast 18 , as shown in Figure 2 . When breakout is required, the method features the step of sliding, into the receptacle 36 of the deck assembly 24 , the breakout plate 38 defining the drill bit aperture 40 shaped and dimensioned to receive the drill bit 42 therethrough, and activating a drive unit of the drill rig 20 to rotate the drill rod 34 to facilitate in si tu breakout of the drill bit 42 engaged in the breakout plate 38 .

[0057] Applicant believes it particularly advantageous that the present invention provides for a drill bit breakout assembly 22 able to eliminate the need for awkward breakout tables , pots andseparate tools required for breakout . The invention further enables easy changeout of breakout plates 38 to suit di f ferent drill bit diameters simply by having suitably-configured breakout plates 38 available . Drill bit breakout is simpli fied by being able to slide a suitable breakout plate 38 into the deck assembly 24 and positioning the drill bit within the peripheral protrusions 44 of the breakout plate 38 and using the mobile drill rig to rotate the drill bit to ef fect breakout .

[0058] In the example embodiments , well-known processes , well- known device structures , and well-known technologies are not described in detail , as such will be readily understood by the skilled addressee . Optional embodiments of the present invention may also be said to broadly consist in the parts , elements and features referred to or indicated herein, individually or collectively, in any or all combinations of two or more of the parts , elements or features . Where speci fic integers are mentioned herein which have known equivalents in the art to which the invention relates , such known equivalents are deemed to be incorporated herein as i f individually set forth .

[0059] It is to be appreciated that reference to "one example" or " an example" of the invention, or similar exemplary language ( e . g . , " such as" ) herein, is not made in an exclusive sense . Various substantially and specifically practical and useful exemplary embodiments of the claimed subj ect matter are described herein, textually and / or graphically, for carrying out the claimed subj ect matter . Accordingly, one example may exemplify certain aspects of the invention, whilst other aspects are exempli fied in a di f ferent example . These examples are intended to assist the skilled person in performing the invention and are not intended to limit the overall scope of the invention in any way unless the context clearly indicates otherwise .

[0060] The use of the terms "a", "an", "said", "the", and / or similar referents in the context of describing various embodiments (especially in the context of the claimed subject matter) are to be construed to cover both the singular and the plural, unless otherwise indicated herein or clearly contradicted by context. The terms "comprising, " "having, " "including, " and "containing" are to be construed as open-ended terms (i.e., meaning "including, but not limited to,") unless otherwise noted. As used herein, the term "and / or" includes any and all combinations of one or more of the associated listed items. No language in the specification should be construed as indicating any non-claimed subject matter as essential to the practice of the claimed subject matter.

[0061] Spatially relative terms, such as "inner," "outer," "beneath, " "below, " "lower, " "above, " "upper, " and the like, may be used herein for ease of description to describe one element or feature's relationship to another element (s) or feature (s) as illustrated in the figures. Spatially relative terms may be intended to encompass different orientations of the contrivance in use or operation in addition to the orientation depicted in the figures. For example, if the contrivance in the figures is turned over, elements described as "below" or "beneath" other elements or features would then be oriented "above" the other elements or features .

[0062] Any method steps, processes, and operations described herein are not to be construed as necessarily requiring their performance in the particular order discussed or illustrated, unless specifically identified as an order of performance. It is also to be understood that additional or alternative steps may be employed .

Claims

CLAIMS1 . A drill bit breakout assembly for a mobile drill rig, said assembly comprising : a deck assembly comprising an upper plate separated from a lower plate via a plurality of spacers of predetermined dimensions , each plate defining a drill rod aperture therethrough, said deck assembly configured to be operatively interspaced within a mast of said mobile drilling rig so that a drill rod is able to pass unrestricted via said drill rod apertures , the deck assembly further defining a receptacle ; and a breakout plate defining a drill bit aperture shaped and dimensioned to receive a drill bit therethrough, said drill bit aperture defining peripheral protrusions configured to engage an irregular profile of the drill bit to arrest rotation thereof ; wherein the breakout plate is slidably receivable within the receptacle of the deck assembly to facilitate in si tu breakout of the drill bit when the drill bit is engaged therein .2 . The drill bit breakout assembly for a mobile drill rig of claim 1 , wherein the deck assembly comprises the upper plate separated from the lower plate so that the respective drill rod apertures are coaxial .3 . The drill bit breakout assembly for a mobile drill rig of either of claims 1 or 2 , wherein the spacers of predetermined dimensions are mounted proximate the respective corners of each upper and lower plate of said deck assembly .4 . The drill bit breakout assembly for a mobile drill rig of any of claims 1 to 3 , wherein the spacers comprise cylinder-shaped spacers with fasteners , such as bolts , passing axially through each spacer and fast at each end with a respective plate .5 . The drill bit breakout assembly for a mobile drill rig of any of claims 1 to 4 , wherein the spacers are laterally mounted on sides of the deck assembly and / or upper and lower plates , said lateral spacers shaped and dimensioned to facilitate the operative interspacing of the deck assembly within the mast of the mobile drilling rig .6 . The drill bit breakout assembly for a mobile drill rig of any of claims 1 to 5 , wherein the predetermined dimensions of the spacers are selected to facilitate operative interspacing of the deck assembly within the mast of the mobile drilling rig .7 . The drill bit breakout assembly for a mobile drill rig of any of claims 1 to 6 , wherein the drill rod apertures are substantially circular with a diameter larger than a largest diameter of the irregular profile of the drill bit .8 . The drill bit breakout assembly for a mobile drill rig of any of claims 1 to 7 , wherein the deck assembly is operatively interspaced within the mast of the mobile drilling rig below a bit breakout clamp and a dust boot of said mast .9 . The drill bit breakout assembly for a mobile drill rig of any of claims 1 to 8 , wherein the receptacle defined by the deck assembly comprises at least one pair of guiding lugs proj ecting from the deck assembly, said at least one pair of guiding lugs shaped and dimensioned to receive the breakout plate slidably therebetween .10 . The drill bit breakout assembly for a mobile drill rig of claim 9 , wherein the at least one pair of guiding lugs proj ect downward from the lower plate .11 . The drill bit breakout assembly for a mobile drill rig of either of claims 9 or 10 , wherein the breakout plate defines U- shaped grooves on opposite sides thereof , each groove configured to receive a guiding lug therein when the breakout plate is fully received within the receptacle .12 . The drill bit breakout assembly for a mobile drill rig of any of claims 1 to 11 , wherein the peripheral protrusions defined about the drill bit aperture are complimentarily shaped and dimensioned to correspond to the irregular profile of the drill bit .13 . A mobile drill rig having a mast comprising a drive unit for rotating a drill rod with a drill bit , the mobile drill rig comprising a dri ll bit breakout assembly interspaced within said mast , the drill bit breakout assembly comprising : a deck assembly comprised of an upper plate separated from a lower plate via a plurality of spacers of predetermined dimensions , each plate defining a drill rod aperture therethrough so that the drill rod is able to pass unrestricted via said drill rod apertures , the deck assembly further defining a receptacle ; and a breakout plate defining a drill bit aperture shaped and dimensioned to receive the drill bit therethrough, said drill bit aperture defining peripheral protrusions configured to engage an irregular profile of the drill bit to arrest rotation thereof ; wherein the breakout plate is slidably receivable within the receptacle of the deck assembly to facilitate in si tu breakout of the drill bit when the drill bit is engaged therein .14 . The mobile drill rig of claim 13 , wherein the deck assembly comprises the upper plate separated from the lower plate so that the respective drill rod apertures are coaxial .15 . The mobile drill rig of either of claims 13 or 14 , wherein the spacers of predetermined dimensions are mounted proximate the respective corners of each upper and lower plate .16 . The mobile drill rig of any of claims 13 to 15 , wherein the spacers of predetermined dimensions comprise cylinder-shaped spacers with fasteners , such as bolts , passing axially through each spacer and fast at each end with a respective plate .17 . The mobile drill rig of any of claims 13 to 16 , wherein the spacers are laterally mounted on sides of the deck assembly and / or upper and lower plates , said lateral spacers shaped and dimensioned to facilitate the operative interspacing of the deck assembly within the mast of the mobile drilling rig .18 . The mobile drill rig of any of claims 13 to 17 , wherein the predetermined dimensions of the spacers are selected to facilitate operative interspacing of the deck assembly within the mast of the mobile drilling rig .19 . The mobile drill rig of any of claims 13 to 18 , wherein the drill rod apertures are substantially circular with a diameter larger than a largest diameter of the irregular profile of the drill bit .20 . The mobile drill rig of any of claims 13 to 19 , wherein the deck assembly is operatively interspaced within the mast of the mobile drilling rig below a bit breakout clamp and a dust boot of said mast .21 . The mobile drill rig of any of claims 13 to 120 , wherein the receptacle defined by the deck assembly comprises at least one pair of guiding lugs proj ecting from the deck assembly, said atleast one pair of guiding lugs shaped and dimensioned to receive the breakout plate slidably therebetween .22 . The mobile drill rig of claim 21 , wherein the at least one pair of guiding lugs proj ect downward from the lower plate .23 . The mobile drill rig of either of claims 21 or 22 , wherein the breakout plate defines U-shaped grooves on opposite sides thereof , each groove configured to receive a guiding lug therein when the breakout plate is fully received within the receptacle .24 . The mobile drill rig of any of claims 13 to 23 , wherein the peripheral protrusions defined about the drill bit aperture are complimentarily shaped and dimensioned to correspond to the irregular profile of the drill bit .25 . A method for breaking-out a drill bit from a mobile drill rig, said method comprising the steps of : providing a mobile drill rig in accordance with any of claims 13 to 24 ; sliding, into the receptacle of the deck assembly, a breakout plate defining a drill bit aperture shaped and dimensioned to receive the drill bit therethrough, said drill bit aperture defining peripheral protrusions configured to engage an irregular profile of the drill bit to arrest rotation thereof ; and activating a drive unit of the drill rig to rotate the drill rod to facilitate in si tu breakout of the drill bit engaged in the breakout plate .26 . The method of claim 25 , which comprises the step of raising the drill rod with drill bit along the mast in order that the drill bit engages with the breakout plate within the deck assembly .

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