by Nick Rossides, General Manager Operations – Global, Swick Mining Services
The increased market requirement for deeper diamond drill holes in the underground environment has become much more prevalent with mining companies globally. The opportunity to reach exploration target depths from an underground platform is entertained by many miners and proving to be both cost- and time-effective when compared to surface exploration drilling. However, this was not always the case.
Swick Mining Services (Swick) were first approached in 2015 to drill out a campaign of deep exploration holes; they made a decision to proceed with the current configuration of Swick’s GenII mobile rig coupled with 112 kW of hydraulic power. A total of nine NQTK exploration targets were designed with 1500-meter hole depths and dips ranging from -39 to -82 degrees. The challenge was to complete each hole within an expected timeframe of 113 shifts. The result was an average of 126 shifts taken to complete each hole and an overrun drill timeline of 117 shifts.
After reviewing their performance, Swick realized that whilst drilling from 0- to 800-meter depth bands, productivity remained on target. It was however at this point that production rates per shift fell below expectations. This could not be rectified despite the use of 6-meter barrels, onboard high flow pumps, mud programs, and drill bit/reamers selections. The drill string torque could not be overcome by the available horsepower at the rotation unit and as a result, the rotation speed slowed. Rod weight was another concern and that was addressed with the implementation of heavy-duty chuck assemblies and feed cylinders. This solution allowed for an additional 27% holding capacity compared to ‘off the shelf’ cylinders, however, this heavily impacted drill time availability by increasing rod pulling/feeding work rate activities.
A review of overall performance forced Swick to look inward at their own limitations, reconsider deep-hole programs management and efficiency, and push the boundaries and perception of what a Swick rig could deliver. This was when the concept of DeepEX was born – a dedicated division within Swick with a more powerful, purpose-built mobile rig, combined with high torque, high pullback feed arrangement.
Swick’s Research & Development (R&D) Team redesigned the GenII mobile rig, focusing on upgrades to the feed rail, which resulted in six times more torque, generated from a 2-speed transmission whilst retaining holding capacity. Depth capabilities are still unknown, however, Swick expects them to be in the vicinity of 2000 to 2500 m (6561.7 to 8202.1 ft) NQTK and 500 m (1640.4 ft) P-size.
Mobile mud recycling systems were also incorporated to mix high volumes of drilling fluid effectively with holding capacities of 3000 L (792.5 gal) and the ability to recycle up to 70% of drilling fluids used on deep holes. This lowers drilling fluid cost exposure and reduces water consumption for the mine.
Swick built a team of dedicated drill specialists, including a manager, a supervisor, and crews, for the sole purpose to focus on DeepEX. The first DeepEX rig has commenced drilling in February 2019 and has since operated across four mines throughout Australia, completing a total of 21 500 m (70 538 ft).
To date, DeepEX has drilled 28 holes with dips ranging from 5 to -75 degrees. Thirty-nine percent of drilling has exceeded depths of 1000 m (3280.8 ft) with the deepest hole being 1607 m (5272.3 ft). The results were much better than Swick anticipated with a 43% reduction in time taken to drill 1500 m (4921.3 ft) from 126 shifts to a staggering 71.
Increased torque at depth has been a defining piece to the success of DeepEX; a testament to its sheer power is its 2-speed transmission, allowing for additional torque when advancing through shear zones or simply retrieving stuck rods or casings, due to adverse ground conditions.
What’s next for DeepEX? A second 112 kW DeepEX mobile has been added to the fleet and has been operational since August 2020. Further R&D have resulted in the introduction of Swick’s ‘hands off steel’ trademark initiatives with the inclusion of rod and inner tube handler, rod presenter, kelly rod holder and automated inner tube extraction. As an addition, Swick has developed a newly-designed rig, targeting +3000-meter depths with 150 kW of power and challenging new diamond drilling depths from underground.
Swick Mining Services prides itself on manufacturing its own underground mobile diamond drill rigs. Since the inception of Swick’s first mobile rig, introduced into the market in 2004, underground diamond drilling has evolved exponentially, due to miners’ continual demand for mobile applications. The unparalleled comparisons between mobile and skid rigs in hole set-ups can now be completed in a matter of minutes instead of hours. Moreover, rig moves that can be carried out within hours as opposed to days. It is this kind of innovation that unleashes improved productivity and lower cost per meter to miners partnered with Swick.
Swick has since grown its fleet of to over 80 underground diamond rigs and drilled over 12 250 000 m (40 190 288.7 ft) of core since their first rig was commissioned in June 2004. One of Swick’s key features is its capability to engineer out as many risks as possible in the drilling cycle and rig moving processes. This same methodology was applied when identifying the increased market requirements for drilling in difficult ground conditions and depths exceeding 1500 m (4921.3 ft).
For more information visit: www.swickmining.com