ROCK TOOLS
Epiroc says its new Epsilon ² premium tricone drill bit will see surface mine blasthole drilling customers enjoy up to 100 % longer distance drilled before bit discard
Top hammers
Paul Moore spoke to the global rock tool majors about their take on bit changes & life in autonomous drilling applications plus the latest on new products and technologies
Autonomous drills are gaining traction all the
time – and that means fully autonomous multipass surface drilling , not just remotely operated . Underground autonomous production drilling is also evolving fast , with development drilling not far behind . This begs the question – if a principal upside of autonomy is equipment having to stop working far less often , then what are the implications for the top hammer & DTH bits that are doing the work ?
Sandvik Mining recently previewed its new Autobit product line for top hammer drilling as part of its Innovation in Mining Virtual Event in September 2020 . Robert Grandin , Sandvik Mining Top Hammer Product Manager said the new bit is aimed at enabling automation in underground longhole production drilling where drills are well suited to autonomy , as they are drilling in one place for long periods of time . But up until now , not that many production auto drills have been used despite the technology being around for some years and 100s of drills from Sandvik and others being sold “ automation ready .” They are being operated manned , which due to shift changes etc can mean 5-6 hours lost per day which can equate to over $ 1 million of lost production time a year per drill rig . A major reason Grandin gave for mines not using automation for production drilling is underperformance of button bits most of which can only drill for an hour or 50-60 m in medium abrasive rock or worse . The new Autobit will be specialised for automation with a much longer first grinding interval allowing two hours or more of use and drilling of 100-120 m – this has been shown in testing . Carbide wear is reduced using its new PowerCarbide grade that self hardens . But also the Autobit drills really well when the carbide is worn due to having superior button protrusion and avoiding contact between the steel bit itself and the rock . At the front of the bit there are also recessions in the steel , delaying this contact as long as possible .
Pejman Eghdami , Executive Vice President ,
Rockmore International told IM : “ Since Rockmore is primarily a drill tool designer and manufacturer , we as a company have to understand drilling equipment technology and how our products interface with such equipment . In the past , the drilling equipment did not particularly depend highly on the drilling tool design with integration between equipment and tooling as a necessary functional constraint . A wide variety of tooling quality and design characteristics could be installed on the drilling equipment . Certainly , drilling efficiency and total drilling cost will vary across different quality and brands of drilling tools for various rock formations and drill settings . But by large , current drill rigs will generally perform with industry standard tooling and be subject to downtime for tooling changes that will be more frequent and time consuming with lower quality tools , leading to higher drilling costs . The newly emerging drill rigs , however , that are classified as autonomous drill rigs , demand tooling that will have to exhibit longer lifetime and reduced wear rates in order to minimise tool changes that would be counterproductive for autonomous settings .”
He adds : “ Since it is desired to minimise the operator interaction with the drill rig for at least a full drill shift , the drill tooling is required to either maintain its integrity or efficiency during the entire drill shift or be changed automatically with a robotic system . The lifetime of the drill tooling for the bits and drill rods can certainly be extended by utilising new materials and design features in the future . These gains , however , will be incremental and not cost effective for every drilling environment or rock condition .”
Pejman also argues that it is the drill rigs that also need further technological development to sense when the drilling tools require a change due to wear or abuse . “ The feedback systems in current rigs today rely on pressure settings to discern for worn tooling , especially for the drill bit . But such systems often fail in their functions and instruct the operator to change the
drill bit when in fact the bit is still adequately usable . In other instances , the feedback system fails to instruct the operator that the drill bit or drill rod is past discard limits due to fatigue wear or other parameters .”
Rockmore sees drill rigs in the future needing secondary feedback systems such as automated measuring of the drill bit diameter or wear indicators to properly inform the operator regarding the drill tool status . “ In addition , automated robotic arms and systems should be incorporated in underground drill rigs to perform bit and rod changes if the drill rig is required to work autonomously with zero or minimal operator interaction . Autonomous drilling , therefore , is still in its early development stages regarding the interaction between the drill rig and the drill tool requirements necessary to offer a drilling operation underground with zero or minimal operator involvement .”
Jose Rodriguez Callao , Robit PLC Sales Manager comments : “ It is clear to everyone that the trend in mining as in other activities is oriented towards automation , but in a mine drilling is only part of the
Robit sees its new diamond coated button bits as part of the solution to enable autonomous drill rigs to drill for longer without interruption
50 International Mining | NOVEMBER / DECEMBER 2020