Boart Longyear Stopemate S36 operating at a mine in Sudbury, Ontario
Horizontal development is common to all underground mines and new technology improvements that help to increase development rates are vital for the industry. Mine Master, the manufacturer of face drilling jumbos including the Face Master 1.4 (very low seams); 1.7 and 2.3 (low seams); 2.8 CC (twin boom, computer controlled) and the 3.0 (twin boom with basket), told IM it is now currently in the advanced stages of developing a “superefficient drilling system for spiral rods with and without air flushing.” Due to exceptional test results the company says it has secured an eight drilling rigs deal with Estii Energia mines, the major Estonia based oil shale mining group. These machines will be used for carrying out preparation works and the new technology has made it possible to reduce the drilling time by 60% according to Mine Master. The company has also signed a contract with Polish salt mining group, KS Klodawa, which has ordered a number of new Mine Master drilling machines. There it estimates that it can reduce drilling times by 40% over alternative technology.
In terms of growth markets, Mine Master highlights Turkey as an important focus area due to the rate of development – in the last eight years Turkey has been achieving 3-15% growth year on year. New mining projects along with highway infrastructure and tunnel works all make it a key market for drill jumbo suppliers. Mine Master has just signed an order to deliver more than 15 rigs to the country and is also currently in negotiations regarding further orders.
Training is just as important for underground operators as it is for those in surface mines. Immersive Technologies continues to further expand its offering for underground mining with the development of a simulator (Conversion Kit) for the Sandvik DD420 jumbo drill. The company believes that the new jumbo drill simulator particularly represents a leap forward in innovation, design and application due to highly realistic drilling physics coupled with an ingenious ‘drilling assistant’ feature to maximise operator training effectiveness. The company states: “The Immersive simulator provides an authentic and comprehensive recreation of the DD420, with cabin comprising of tramming controls, drill and boom controls, jack controls, dials, gauges and a variety of the ancillary functions. The controls are all based on the fully-hydraulic version of the machine, with the software supporting both closed-cab and open-cab arrangements.”
A new type of “Special View” is also offered in which the operator can use an integrated dash-control to “walk” around the outside of the cab and navigate within the 3D virtual world to inspect aspects of the development heading. This is a key feature for jumbo operators where regular external inspections can form part of their daily routine in ensuring correct drill hole alignment.
Immersive says that particular care and attention to detail has been put into the visuals for the drill, setting new standards in 3D graphical machine models for mining simulations. The simulator utilises the full 360 degree display of the Immersive Technologies UG360 simulator platform in order to provide a highly realistic underground setting within which to conduct training. Other aspects of machine operation such as tramming and jack operation are covered by a comprehensive set of scenarios, resulting in a complete training experience for all jumbo drill operators.
Atlas Copco has announced two new face jumbo rigs – the Boomer E1 C-DH and the Boomer M1 L. The single boom, diesel-hydraulic multipurpose Boomer E1 C-DH is specifically designed for mines or construction sites lacking water and electrical infrastructure. The machine comes with dual onboard 450 litre water tanks and a six-cylinder, 173 kW Deutz diesel engine to drive the rig, its boom and the drill’s hydraulic pumps. The rig is one of the largest dieselhydraulic face-drilling rigs on the market, with a coverage area of up to 95 m2. This is a 38% improvement over its predecessor, the Boomer L1 C-DH drill rig. According to Johan Jonsson, product manager for Atlas Copco Underground Rock Excavation, the new rig provides unique advantages in the field. “In the case of a new project, the Atlas Copco Boomer E1 C-DH drill rig can be used to get started even before water and electricity are installed at the job site,” he said. “Mines begin earning sooner, and contractors are able to get ahead on their schedules.” Jonsson also pointed to the new drill rig’s advantages in widening existing tunnels or adding bolts in older workings, as it is not necessary to install power and water infrastructure to support the rig on-site.
The multipurpose capabilities of the new rig are enhanced with the addition of the optional basket attachment. This allows the Boomer E1 CDH rig to be used as a bolting rig and as a utility rig for drilling holes and installing ventilation ducting, among other tasks. The Boomer E1 CDH drill rig comes standard with Atlas Copco’s Rig Control System (RCS) with the option to upgrade to an even higher degree of automation. The model comes with a COP 1638, COP 1838, or COP 2238 rock drill with a dualdamping system for optimum service life. The BUT 45 heavy-duty boom is equipped with a double-rotation unit for plus/minus 190° feed roll-over and plus/minus 135° feed rotation, providing the operator with fast and accurate positioning between holes. It comes with a 2.5 m boom extension and 1.8 m feed extension. The new Boomer rig also has a BMH 6000 series hydraulic feed.
The latest single-boom face drilling rig from, the Boomer M1 L was specially designed for development and production drilling in low-tomedium height mines. With a height of 1.8 m, which is slightly higher than previous low profile rigs of this type from Atlas Copco, it is aimed at room and pillar mines with roof heights of 2.2- 2.5 m. The company states that it has an extremely strong carrier as well as oversized wheels compared to similar rigs in the range.
“This is the perfect rig for the rough and tough world of low vein mining in room and pillar operations – especially where there are long distances to be covered,” says Peter Bray, Product Manager at Atlas Copco’s underground equipment division. Other advantages include an improved flexible boom, simple controls (Direct Control System 2 – DCS 2) as well as a choice of COP 1638 or COP 1838 rock drills. The rig is also designed to be extremely easy to service to keep downtime to a minimum. A prototype of the Boomer M1 L was successfully tested by the Polish mining company KGHM which has since placed orders for several units.
The new jumbos from Oldenburg have a modular design to allow for a high degree of customisation for each mine
Oldenburg Mining offers a complete line of drill jumbos for applications in underground face drilling and benching. Doug Wilson, Director of Marketing told IM: “The modular product offering is designed to meet the unique challenges of each mine – from manoeuverability and air quality to operator convenience and safety.” Its recently expanded line of drill jumbos includes two new models – the DPIN and DPXH. The single-boom DPIN features a 1.98 m chassis and provides 6.7 x 9.5m boom coverage. The high-volume twin-boom DPXH features a 3.22 m chassis and provides optimum boom coverage of 12.2 x 18.9 m.
Oldenburg also offers a variety of power options – including diesel, electric and dualpowered. The drills are equipped with Tier 3 and Tier 4 compliant engines for maximum production, with the all-electric option MSHA-approved for mines with gas risks. An improved, sealed cab design with expanded certified ROPS and FOPS options has reduced noise and increased safety and working conditions for operators. In addition, High Efficiency Particulate Air (HEPA) Filtration improves air quality in the cab. Improvements to the cab’s interior allow for enhanced comfort, and recently introduced ADS 400 and 500 operator assistance packages make the jumbos easier to operate. Oldenburg says it has experienced significant growth in its core North American and Latin American markets by “solidifying strong partnerships throughout both regions.” The company believes its main strength is in unique modular designs that allow its jumbo drills to be equipped for each specific mine.
Mining Technologies International’s (MTI) drilling knowledge and experience has been developed in its home market of the Sudbury Basin nickel mines, but the company argues that this has allowed it to develop unique strategies that is has also been able to apply successfully in the international mining market.
Aside from its full line of OEM drill jumbos including the Drift Runner, Ramp Runner, Tunnel Runner and Vein Runner models, MTI Product Specialist Paul Morissette points to developments in modular conversions as the main reason for MTI’s international success. In MTI’s Modular Conversion service, the Sudburybased manufacturer builds and assembles components that fit part of a ‘module’ which can then be fitted onto any other manufacturer’s carrier. The entire process, says Morissette, saves the customer from making high-cost capital replacements from OEMs before the vehicle’s lifespan is complete, with the long lead times that can involve. “The boom and the front of the frame are what get most of the action, so we can set up a new drill panel or a new boom individually, and have the module fit perfectly onto their carrier.” MTI believes this service is unique to its offering, and allows operators to preserve their equipment value by replacing only vital components – providing “ultimate flexibility and most cost effective approach to renewing and replacing parts.”
Contract mining group Cowin & Company, recently made a request to JS Fletcher & Co for an explosion proof diesel powered jumbo drill with an enclosed operator’s cab. In response, the engineering department developed the first MSHA approved diesel drill working in West Virginia, and the first in the US in decades. The cab is certified for the MSHA canopy ratings and is kept cool by a hydraulically adjustable fan. Having an MSHA approved explosion proof diesel was important to Cowin, protecting employees from potential methane explosions, while also eliminating reliance on an electrical power source and cables.
JS Fletcher sees one of its main strengths as its vast in-house database acquired from many previous custom built equipment endeavours. This allows Fletcher to have a quick design turnaround, by having answers ready at hand. When presented with the concept of an explosion proof electric jumbo drill for coal mining group, Alpha Natural Resources, Fletcher was able to simply reconfigure a previous carrier design to house the electrics instead of the diesel components and traded the enclosed cab for an open operator’s area covered by an operator’s canopy.
Both the Cowin and Alpha machines made use of Fletcher’s existing designs, including the PERB45 boom, feed and rockdrill. The boom, used since early 2000s, is both proven and reliable, according to the company. It also provides convenient manoeuverability in smaller drift applications.
Alpha then requested the creation of a beam setter with the same basic carrier as the jumbo drill. Fletcher was able to do this by creating a similar machine, replacing the end of the boom with a beam manipulator arm, allowing steel beams to be set in cycle during mining. Behind the operator station was a lifting, extending platform, allowing the miners to bolt the beam assemblies together. This was important in reducing potential injury during lifting and reaching, while also increasing productivity.
Benefits of instrumentation
Jussi Puura, Product Manager Tunneling Jumbos at Sandvik, recently authored a paper on the benefits of instrumentation in face drilling. The paper states: “The goals of successful excavation are to achieve the highest quality possible of the mine tunnel profile, a high advance rate and to minimise the drill and blast cycle time while maximising the utilisation of the equipment. In the future, development will move toward increased production rates and tighter regulations regarding excavation quality and environmental considerations. All of this will put pressure on the functions of the equipment used in excavation, and on the management of excavation. Use of instrumented drill rigs is gaining support in the mining community as the benefits of these systems are becoming apparent. While the traditional way of working is based on the operators’ expertise in the drilling process, instrumentation on drill rigs provides possibilities to achieve the same excavation quality as with an experienced operator regardless of the operators’ competence level. Adding data collection features to the drill rig provides also possibilities to identify problems in the drilling and blasting process and correct them to achieve better working efficiency and cost savings.”
The progress of excavation work in development drilling is described by parameters such as pull-out and advancement per round. Pull-out refers to the percentage of the drilled round’s length that has been advanced after the blast. The advance per round on the other hand indicates the distance advanced in the tunnel after the blast. The length of the round is considered to be the perpendicular depth from the plane where the holes are designed to start to the plane where the holes are designed to end. Round length is one of the most important parameters in designing excavation work, as the excavation advancement depends on the selection of an optimal round length. Savings in excavation work are largely based on a carefully created plan, and on the drill rigs accuracy in implementing the excavation according to the plan. A good drill plan is created with good theoretical knowledge of the blast as a basis. Hole distances are designed based on the type and amount of explosives used or vice versa. A good plan can be created but its full potential may not be reached because of inaccuracies in the execution phase.
Hole start positions are not a problem because the operator can see the starting points of the holes for example by aiming to a painted pattern on the wall. All may seem perfectly clear in the mine drift, but due to operator’s or drill rig’s inability to drill holes exactly on correct angles without aiding functions, the actual holes inside the rock end up having distances different to the planned pattern. This in turn means that the explosives inside the rock will not be in their designed places. The resulting inaccuracy in the hole bottom leads to bad pullout, poor advance or in the worst case a failed blast.
Ability to see the angles of the drilled holes in the drill rig gives immediate benefit in eliminating problems. Added with a hole position instrument, the designed pattern can be executed correctly every time. Hole position and angle display for the operator completely removes the need for marking up the face or spotters in the tunnel which leads to further time saving. This also removes the human aspect of variation in the painted pattern. Higher probability of a successful blast and higher advance per round translate to savings in time and money in the excavation operation. Inaccuracy in the hole length can lead to difficulties during blasting and cause unevenness in the tunnel walls, back, and floor. An error in depth alignment will repeat itself in the following rounds and make the next rounds even more difficult to drill and load. A good advance and well designed hole angles also help in coping with sockets (commonly called bootlegs). Bootlegs are hole ends of the previous round that are left when the full length of the round is not achieved. Not drilling in or near bootlegs is both a legal requirement and a critical safety issue because there can be un-detonated explosives left behind in the bootlegs. If the pull-out of the round is improved it is easy to see that the bootlegs get shorter and the problem is minimised.
Profile quality also has an effect on the function of other underground drills in the mine site beyond the work cycle of drilling and blasting for drifting purposes. A good profile quality with low blast damage will also reduce scaling time and lessen the need for immediate rock reinforcement. A good quality floor profile has long term effects on the durability of the machines by creating a more even road bed.
Sandvik DD and DT-series drill rigs can be equipped with instrumentation to provide the operator with accurate boom positions and angles and to provide the worksite with valuable feedback information about the actual drilling
done underground. Sandvik instrumentation options TCAD and TMS can be fitted on noninstrumented rigs to combine the benefits of instrumentation and automation with the robustness of traditional hydraulically or electrically controlled drill rigs. TCAD stands for Computer Assisted Drilling and it is a complete navigation and aiming tool designed for accurately executing pre-designed drilling plans with Sandvik drill rigs. The TCAD system provides the operator with a drilling pattern on screen together with boom positions and angles. It can also be equipped with data logging capabilities to report the actual realised drilling patterns and drilling parameters such as penetration rates and drilling pressures.
The TMS measurement system is aimed to harsh conditions, especially for machines with only a safety canopy, to provide the operator with accurate information on hole angles and lengths. As seen in the examples, even having an angle display to ensure that the hole end coordinates are as planned for blasting, has big effects on the excavation cost by improving pullout, and securing successful blasts.
The TCAD position and angle system is delivered with tunnel curve and drill plan design software. Drill plans can be transferred to the drill rig with a USB memory stick. Before operation the operator simply selects the correct drill pattern and curve from the memory. The rig position and orientation is determined by using the tested tunnel laser method.
Both systems are designed for robustness. The systems are completely parallel to the drill rigs normal operation. In case of failure in the instrumentation system, operation of the drill rig is unaffected and still able to carry out boom movements and continue effective drilling. This separation is important in aggressive mining environments.
Production drills
Production drilling requires a unique approach, particularly with regard to access in the production area as well as operator safety. The StopeMaster and StopeMate rigs from Boart Longyear are designed for the tight and narrow spaces typically seen in underground mining operations. Sid Gaitonde Global Product Manager for Capital Equipment at Boart Longyear told IM: “Each is specifically designed for underground applications allowing for superior access, mobility, flexibility and productivity in tight access locations. Both offer durable and compact solutions for developing underground shafts. For enhanced safety, the rigs are developed with heavy-duty hydraulic hoses to protect the driller from hose rupture and guarding for protection from moving parts. Removing the operators from the immediate drilling area, the rigs can be controlled with a remote positioning system up to 25 m away. The rigs also come equipped with emergency stop circuits to cut the power to the drill in the event of an incident.”
Creating larger stopes can help underground mines accomplish greater productivity, by allowing to use of larger equipment and the faster removal of materials. The same also applies to long-hole drilling, releasing more material per blast. But larger stopes and longer holes aren’t always possible, as not all rock formations are suitable for this application. These situations requiring a need for narrow vein use and tight space access are the core markets for the StopeMaster and the StopeMate machines. Both are equipped with a pneumatic top hammer production drill that features a 360° rotation for greater flexibility. With a rotating/pivoting traverse allowing for versatile configurations, these top hammer drills are better suited for smaller hole drilling. This configuration ensures precision drilling in both parallel and straight applications, and accurate operator control in drop-raise, cable-bolting, fan-drilling, ring-drilling and parallel-drilling applications. Designed for bulk mining applications, the StopeMaster is capable of drilling holes measuring 64 to 106 mm in diameter – at up to 35 m depths; while the smaller, more compact StopeMate can fit into a lift cage and drill holes at depths of 12 to 15 m. Both drills are offered in standard and HX versions. The StopeMate HX features an added hydraulic positioner, and the StopeMaster HX features the same positioner as well as a self-propelled diesel option. The self-propelled version can disengage gears in order to facilitate towing where required.
Simba: Atlas Copco’s new Simba E7 C production drill
In long hole production drilling, a range of new Simba drill rigs have been developed by Atlas Copco. The company has introduced four different versions of its Simba rig concept – Simba ME7 C, Simba E7 C (plus an ITH version) and Simba W7 C – that it believes give miners the widest possible choice of solutions for different mining environments and the ability to adapt each unit to suit individual conditions and requirements. All four rigs are designed for long hole drilling (up to 51.2 m, theoretical depth) in medium to large drifts. Equipped with COP1638, COP2550 and the powerful COP 3060MUX top hammer rock drill, they perform ring drilling both upwards and downwards. Together with the ITH version of the Simba E7 C, which is equipped with a DHR6 rotation unit, the rigs form a complete production fleet range.
The Simba ME7 C drills parallel holes spaced up to 6. 9 m apart with a hole diameter of 51-89 mm; while the Simba E7 C drills parallel holes spaced up to 6. 1 m apart with a hole diameter of 89-127 mm. The Simba E7 C-ITH drills parallel holes up to 5.2 m apart with a holediameter of 92-178 mm. The Simba W7 C is fitted with the Wassara water-powered hammer for special applications.
The BUT 45 boom used on these rigs is extremely sturdy, enabling them to carry the most powerful rock drills and other types of equipment. At the same time, Atlas Copco states that the boom increases accuracy and control and is highly adaptable for different needs. Automatic rod handling is also a standard feature on these rigs.
The new Simba range has been field tested successfully in Sweden and Australia and have been available since March 2012. At the Zinkgruvan mine in Sweden, the Simba ME7 has been drilling significantly faster and better than the older Simba M7 according to the company.
Underground exploration
A Boart Longyear LM90 underground exploration rig at the St Ives gold mine, Western Australia
Exploration in existing underground mines is crucial to increase reserves and locate orebody extensions. Boart Longyear offers an innovative range of underground diamond coring equipment – the LM Modular diamond drill series. The LM series includes the LM30, LM30SS, LM55, LM75 LM90, and the LM 90A. The drills range from small-compact to robust drills that use electronics and can be used by operators learning the trade. The LM series components can be interchanged to adapt to diverse on-site situations, and are capable of both conventional and heavy duty wireline core retrieval.
Being able to take advantage of the latest diamond bit technology, the LM Series can use the company’s new Ultra Matrix (UMX) bits. The series include the SSUMX, 07UMX, 09UMX and the recently released 10UMX.
Arctic Drilling Company supplies underground exploration rigs with a 180° vertical drilling radius
Sid Gaitonde comments: “Engineered to drill faster, last longer and outperform existing bit technology in a wide range of drilling conditions and ground formations, the UMX uses advanced metallurgical formulas with larger impregnated diamonds to provide increased penetration capabilities. The UMX bits transfer easily from one ground formation to another.”
Arctic Drilling Company (ADC), based in Rovaniemi, Finland manufactures innovative underground drilling rigs as well as distributing high-quality products from other manufacturers in the industry. Customers include Agnico Eagle, Gold Fields Arctic Platinum, Kevitsa Mining and Lappland Goldminers. The custom-made diamond core underground exploration drilling rigs have a minimum-rated traction force of 6 t, a 360° horizontally rotating drilling platform, a 180° vertical drilling radius, and a wireline winch with a 1,500 m drum capacity. ADC cites the key benefits of the rig as its fast and easy set up time, because of the rig having a rubber, trackmounted chassis; the fact that it is easy to drive in any terrain (including gravel, sand or mud); a driving speed of 5km/h, making them easy to steer.
Rock drill and bit technology
A Doofor DF550L rockdrill installed on a Herrenknecht TBM
Doofor has successfully introduced a new underground mining rock drill, the Doofor DF550L, in the 17 kW class. The rock drill has a patented Doofor piston, which enables the strike impulse to travel efficiently in the drill steel. The company states that DF550L has a high frequency and an efficient valve system for improved penetration and prolonged drill tool life time. Rotation is created by Danfoss OMS rotation motor and the rotation motor can be installed on the right or on the left hand side according to customer requirements. The DF550L has a very low overhead profile, which is suited to mine drifting. It has also been a component of choice for TBM manufacturers.
In drill bit technology, Element Six, a global leader in synthetic diamond supermaterials, is launching a range of new highly engineered percussive diamond inserts (PDIs) for drilling operations in underground mining. The PDIs have specifically been designed to deliver extreme performance under challenging conditions encountered during the drilling of hard rock such as abrasive sandstone, quartzite and basalt. The company says the PDIs “are highly compatible with the majority of drilling bits and comprise Element Six’s new multi-layer polycrystalline diamond technology. This technology ensures the efficient delivery of energy to the rock face through high impact resistance and exceptional wear resistance in demanding formations during drilling operations in underground mining.” These characteristics result in a consistent rate of penetration in hard rocks, outperforming bits using conventional tungsten carbide inserts, according to the company. Element Six has conducted extensive field tests in Europe, South Africa and the US, which it says have demonstrated an improvement in the insert life by four to six times compared with conventional inserts.
Joe Dalton, Mining Business Unit Manager at Element Six Hard Materials comments: “these technically advanced properties translate into tangible economic benefits to rig operators”. The PDIs significantly crush the drilling cost per metre, providing a competitive advantage and higher profitability. The percussive diamond inserts also enable rig operators to improve the rig utilisation and reduce downtime as the need to regrind the inserts is eliminated.
Robit Rocktools, the Finnish manufacturer of high quality drilling tools for mining applications, is known for its threaded button bits for rock drilling. The company told IM that it now has a strong foothold in the underground business, and that its bits designed for tunnelling and mining have proven popular in key markets. In 2011, Robit states that it continued to have a strong presence in the Scandinavia and CIS underground mining markets but in addition has made significant strides in its presence in Asia due to a new factory in South Korea. This factory has also opened new doors for the company in Africa and the Americas, due to a new ability to offer the whole package between the drifter and the rock. Last year, Robit launched a completely new product line of button bits – the HTG series. In 2012 Robit says that it focussed on fulfilling this product line to meet all customer needs and to further improve the series based on customer feedback.In 2012, Robit has also launched a tool that will assist customers with high demands for hole straightness, as well as testing a new bit design for extremely abrasive conditions and the results so far have been very successful.
Rockmore International has a new DTH hammer in its emerging Deep Hole series, the ROK 500DH, which has both underground and surface applications. This 127 mm range hammer has a number of new innovations and features characterised in this new Deep Hole class of hammers, according to Rockmore. It is the first release in this new hammer series and is targeted to drill 140 to 152 mm diameter holes. Designed to increase drilling effectiveness and efficiency in deep hole applications, the ROK 500DH incorporates engineering advancements for drilling in DTH applications. Unique drilling requirements in some applications demand drilled holes exceeding 300 m deep and include high volumes of water, thus presenting great challenges for conventional DTH hammers to drill effectively. The ROK 500DH has been designed specifically to handle these challenges by incorporating new airflow and component design advancements, primarily in the air ports of the wear sleeve and piston. The hammer is rated for use with large compressors: 24.1 bar at 25.2 m3 / min; however, it can readily accept greater air volumes and pressures from larger air compressor packages. The upper and lower hammer air chambers of the 500DH have been modified accordingly in order to achieve optimum drilling efficiency. The advanced piston design also offers maximum blow energy with each stroke to the bit, allowing for superior hammer and bit penetration rates in all drilling conditions.
A new bit retention system was also developed for this hammer in order to alleviate broken bit heads falling to the bottom of drilled holes when bit shanks fail catastrophically. A new bit shank, the DH500, was developed in conjunction with the new retention system, eliminating the need for bit retaining rings present in conventional hammer designs. The bit is retained in the driver sub by uniquely designed lobes located on the bit shoulder. If in the unlikely event that the bit breaks from the shank body during drilling operations, the bit head may be retracted out of the hole as retained by the lobes on the bit and driver sub, thus eliminating bit retrieval that is often timely and costly.
The traditional foot valve, or blow tube component, has also been eliminated in the DH500 shank concept. Foot valve breakages on DTH bit shanks during drilling operations are catastrophic since the hammer will cease to function immediately after such a failure. This is particularly damaging to drill time efficiency if such interruptions occur in deep hole applications, requiring the hammer to be retrieved out the hole for bit replacement. The DH500 shank alleviates such down time risk by the elimination of the foot valve component.
Conventional hammers often exhibit low penetration rates when used in deep hole applications when high water volumes exist in the hole while drilling. But due to the design advancements, Rockmore states that the new ROK 500DH drills exceptionally fast in dry hole conditions as well as under high water volumes.
As with all of Rockmore’s DTH hammers, the 500DH uses Rockmore’s patented SonicFlow technology, which optimises airflow by simplifying and streamlining the air path to minimise backflow and turbulence, thus delivering more energy to the piston. Optional back reaming buttons on the top sub also contribute to increase hammer life. Field testing of the SonicFlow design was found to result in faster penetration rates and greater overall DTH hammer efficiency.
The company states: “The ROK 500DH has been engineered to withstand the toughest rock drilling conditions. The solid piston design is made from an advanced material that is case hardened, combining high strength with supreme wear resistance. The high frequency, reciprocating piston is designed to strike the bit with maximum force. An innovative design, unique to Rockmore hammers, reduces the number of hammer components, thus reducing the amount of component wear points, making hammer service simpler and less expensive. Unique lead threads on the top sub and driver sub ensure easy coupling and uncoupling of the hammer.” IM