America the brave – underground mining technology in North America
Published in: World Mining Equipment
Date: 6/1/1998
By: Casteel, Kyran
Coal mining machinery, drilling, and mine planning systems are some of the mining technology fields where US and Canadian mining machinery suppliers have been on the cutting edge for a number of years. The introduction of automated machinery for the underground mining market is one of the biggest changes in the industry. Modular Mining of Tucson, AZ, and Ttech of Canada are two of the leading firms in this area.
North American firms have long been at the cutting edge of technology, in the underground mining market. Canadian and US suppliers are amongst the leaders in field such as mine planning systems, coal mining machinery and drilling. Here we take a look at some of the latest developments in the various fields from coal to software.
Auto-mining
One of the big changes sweeping across the underground mining market is the introduction of highly automated machinery. North American, Australian and Scandinavian mines have been leading this field due in part to factors such as higher labour costs and it follows that much of the latest technology comes from these areas.
By using semi-autonomous, remotely guided LHDs and drilling equipment, mining firms have the opportunity to boost output considerably. Removing machine operators from the working areas or even the mine itself in some cases, can also increase overall safety levels, as the risks of miners being near the face during blasting or other potentially hazardous activities can be minimised. But to achieve this aim, firms have had to develop new technology that allows data to flow via buried cables or leaky feeder radio networks that are tough enough to cope with harsh underground mining applications.
Radio-controlled load haul dump (LHD) machines first began operating in the mid 1970s and benefits in long-hole stoping applications for example, included improved ore recovery and safety. With vertical retreat mining methods, automation in narrow ore bodies brought the ability to avoid drifting in waste to establish drawpoints, as well as the recovery of ore remnants abutting backfilled slopes. But these systems were comparatively crude by today’s standards and their use was curbed by the limitations of the hardware.
Tucson-based Modular Mining is putting considerable effort into developing new wired communications systems for this market. Token ring communications have been one of the key technologies for Modular’s investment, as this is seen as an important link in the fast-growing market for machine control systems, Modular’s most recent improvements in token ring technology have seen the introduction of receive signal strength indication (RSSI) systems, narrow baud digital modems and fault detection equipment.
The firm’s token ring network technology is designed to carry data and is used with mobile equipment, such as trains or LHDs. Communications conflicts are prevented by a strict protocol that passes the token, indicating when each node should initiate a transmission. Data can be sent and received from the mobile machines through micro-cell radios, located at various points around a mine and linked together by cables. When a train, drilling rig or LHD sends a data packet through the token ring network, this can be picked up by several of the micro-cell radio receivers. A master loop controller on the network then uses RSSI to determine which of the micro-cell radios has picked up the strongest signal. The RSSI is able to show which of the radios is closest to the machine and the system then sends back data using only the micro-cell that registered the strongest signal ensuring the best possible transmission. The switch to more efficient, narrow-baud UHF digital modems has also been a major improvement. These modems are designed to use digital processing software (DSP) to run the network at any rate from 1,200-9,600 baud and allow for better data throughput and greater operating flexibility as a result, Before DSP modems were introduced, users had to change hardware to alter transmission rates whereas this innovation means that only the software has to be changed.
The token-ring network can also provide personnel tracking through the use of radio frequency identification (RFID) tags. This enables mines to track entries and exits through monitored portals and to block personnel access to restricted areas. Modular says that its technology can even automatically detect signal faults and bypass affected areas if necessary, leaving the rest of the network operational. Where breaks occur in the network, the system terminates around the break and continues operating downstream devices via built-in battery power, And the only limits to Modular’s token ring network, are the distances between the micro-cells themselves. This allows for a virtually unlimited network, whereas some competing systems are restricted by the total distance covered.
Another big player in developing vehicle automation systems has been the Canadian firm Ttech which is part of a project to develop an advanced TeleRemote LHD control package, called TRAM. Other participants in this collaborative Canadian scheme Include Cameco and the Canadian Defence Research Establishment and the commissioning trials have already been successfully completed at the Camecois Eagle Point Mine in Saskatchewan. However, operational tests are now underway following the installation of a more advanced broadband communications system by Automated Mining Systems of Aurora, Ontario, just a few months ago.
Earlier radio systems worked on the line-of-sight approach in which the operator stands removed from the hazardous area, at distances of up to 200 m. But this technology is limited, as the radio signals are no longer reliable once they pass round sharp comers and the operator is still needed to tram the machine to the dump point. Ttech’s project is aimed at improving on this approach, allowing the machine operators to be based in another part of the mine or even in a control room on the surface.
A key part of Ttech’s approach is the development of a computer-based interface that supports self-diagnostics for the LHD. Control and sensing nodes for the LHD are connected through a vehicle control area network (VCAN), which also transmits the machine’s operating health data, Through the application of this technology, Ttech claims troubleshooting on the actual machines is now far easier and the operating flexibility is far higher than for previous LHD remote control set-ups. Much of the electronic systems used in Ttech’s LHD control system has been well-proven in the automotive industry but has been ruggedised for the tougher mining environment. The sophistication of Ttech’s LHD package has also been permitted by technological advances in other areas, such as in communications systems. The recent development of smart tranceiving modems offering 990 MHz frequency hopping (440 channels) facilities, have allowed for more efficient two-way communications to an LHD as it operates. Ttech is understandably optimistic about the potential for this project and has published a paper on the subject, from which much of this information has been gleaned.
Integrating existing underground systems has been an important factor in improving underground The Noranda Technology Centre has been concentrating on this field with its system for integrated automation of mines (SIAM) project. This is being marketed by STAS Mining Division, under license from Noranda.
SIAM comprises four main systems; multi-media communications, video-assisted teleoperation, automated machine guidance and automated bucket loading. These can be used separately or merged, without having to change any of the componentry and the technology can also be upgraded if required to incorporate new systems, as they become available. Based on a network of distributed antennae linked by CATV coaxial cables, the system can work on fixed or mobile equipment providing data, digital video and voice communications and can also be used for personnel location.
In potash mining, the drifts are often very straight with relatively smooth sides providing an ideal waveguide for transmission in the 800-900 MHz range according to Noranda. As a result, the SIAM antennae can be distributed over a wide area and still provide good coverage along the drifts, as well as into cross drifts and side tunnels. At IMC’s potash mine in Canada, 15 km of CATV cable was installed initially just to support the voice communications. This system was later upgraded with the addition of 20 SIAM mobile data radiomodems distributed on two networks. Each of the modems connects to a PLC controlling equipment such as conveyors and three radiomodems using digital video are also being installed onto continuous miners. This set-up allows real-time voice and data communications around the mine and is said to bring a significant improvement to overall operating efficiency.
The technology is also being used with LHDs and allows for full remote control of these machines in the stope, to increase overall safety, Features include real-time video links and the Niobec mine (also in Canada) began using this system to allow telecontrol of an LHD in the stopes earlier this year. The mine features the transverse open stope mining method, with three to four drawpoints used to access the ore block and the operators can be located in a safety bay or further down each drift, Utilising this SIAM technology has the potential to bring a 5-6% improvement in ore recovery, according to the firm.
Ground-up Improvements
The Series V Scaler from Getman is the product of a two-year development programme to boost productivity and reliability, as well as ease servicing, which has seen a revamp of virtually every design feature. The chassis has been heavily strengthened, a different engine fitted and both the hydraulic and electrical systems have been improved.
Dana Getman, president of Getman, said, “We believe that the concept of the concept of inherent stability, without the need for outriggers is still the most efficient approach for this application. This is the fifth generation of improvements to the basic concept and utilises the benefits gained by computer stress analysis and the latest in component availability.”
Redesigning the chassis strengthened stress points such as the articulation joint, while the new model also had to accommodate an engine installation turned by 180 [degrees]. This was done to move the transmission forward to the front of the engine compartment and eliminates the need for a drive-through rear axle. Power comes from a Deutz BF4M1013C water-cooled diesel delivering 91 kW, although Cat engines with similar outputs are also available. The Clark 18000 transmission is retained as standard but now features electronic control although optional Clark or Funk systems can be fitted for higher power installations. Load-sensing hydraulics are fitted which boost working efficiency and reduce heat generation while the electrics benefit from a 24V high-output alternator. The vibration-damped cab is now located on the right rear-side of the chassis and provides better operator visibility and access. Electric operated control joysticks are now fitted and cab options include air-conditioning and extra noise suppression systems.
Sherman advances
Not the General, not the WWII tank, Sherman is the Texan town where Svedala Reedrill is based and bidding to expand, Acquired in April last year, Reedrill brought to Svedala Industri the one of widest varieties of hole drilling equipment manufactured by any one company. For surface construction work, quarrying and mining, this range includes Texoma auger drilling equipment, the combined Reedrill and Gardner Denver spread of rotary blasthole drills and tophammer surface drilling rigs, and — through an alliance formed in 1995 — the Cubex range of surface Megamatic ITH units. These products fit extremely well with Svedala’s comprehensive equipment lines for the construction and mining industries. Even though the new parent does not have previous experience in the drilling market, the acquisition also takes Svedala underground, since both the Canadian Cubex operation in Winnipeg and Gardner Denver build jumbos for underground drilling in mines and civil excavations.
Both the Cubex and Gardner Denver underground ranges represent a challenge for Svedala Reedrill with very considerable market potential, albeit for somewhat different reasons. The Canadian operation is a relatively new one that has been building an excellent reputation in the world. Gardner Denver, on the other hand, dates back to 1859 and was probably the world’s largest supplier of underground development and production drilling jumbos when pneumatic equipment was dominant, but has for some years focussed on the North American market. Combining Svedala’s financial and marketing capabilities, with the Cubex and Gardner Denver teams’ engineering skills, is likely to bring sales growth.
The underground Gardner Denver range, which Reedrill acquired in 1992 comprised six standardised and modular hydraulic jumbos, designed for development drilling, primarily in Canadian nickel mines and US underground limestone operations. The latter are reckoned to account for around 60% of the US market for development drilling jumbos. In both segments Gardner Denver still has a very large market share. There were however a variety of other loyal customers in the Americas and elsewhere, a notable one being PT Freeport Indonesia which has always and exclusively used GD jumbos underground.
The main mine workhorse in the line is still the MK (Mine King) 45, which is widely used in the Sudbury nickel mines while the MK35 is used in Manitoba. The other models were the MK20, MK65, and the TK (Tunnel King) 140 machine which can have two or three booms, with or without man-basket. GD has generally based multiple configurations on a small range of basic models and the machines have a reputation for being extremely robust and very reliable — some of the drills currently in operation have been working for 20 years. Since the GD operational headquarters moved from Roanoke, Virginia to Sherman, these machines have been modified but not replaced, the firm’s underground jumbo product manager Rob Ambrose told WME. However, the engineering team has put a lot of development effort into a newer machine, the MK10, he pointed out. The MK10 HDE is a designed for small and narrow vein mines. The first unit was supplied to the El Bronce mine in Chile, equipped with both a Deutz 65 kW diesel engine and a 56 kW AC motor so it can drill using either diesel or electric power. Two more units have been built since, one for Australasia and another for Mexico.
Drilling three-ways
Canadian firm MTI’s developments in the underground drilling line have also been significant, The company set up a tri-partite joint venture for this market with Norwegian company AMV and Ingersoll-Rand’s French subsidiary, Montabert (WME Dec 1996) and the equipment range is now benefiting from this deal. The MTI jumbos feature Montabert’s advanced Intelsense II drill monitoring package, which is said to improve drilling efficiency. This works by automatically matching the feed pressure to the hammer pressure and operates without the need for complex electronics. According to Montabert, Intelsense II allows for the lowest cost per metre drilled in the industry (although Atlas Copco, Boart Longyear and Tamrock would probably disagree), maximising both productivity and performance. Because Intelsense II is a proven technology, MTI is also now offering customers the option to retrofit the package to existing machines. Currently, the firm is kitting out around two machines/month with Intelsense II and the customer list includes several major names such as the Kidd Creek mine, Brunswick Mining and Smelting, Falconbridge operations as well as a number of Inco mines.
Black gold
The coal equipment sector is an area where North American firms have long ranked amongst the key players. US firms such as JOY Mining Machinery and Long Airdox have been particularly active in this field in recent years, having acquired several smaller companies around the globe, As a result, it should come as no surprise that much of the technical innovation has also come from Joy and Long Airdox.
For its part, Joy has introduced several new continuous miners in the last few months, as well as continuing to develop other products and systems such as longwalls or battery haulers. Joy’s 17CM and 14CM9AA continuous miners are amongst the firm’s latest product introductions to actually hit the market and these share a number of features with the 12CM27 announced recently (WME May 1998).
Because of its AC drive, Joy says the 17CM miner has several working advantages over its competitors. The variable frequency and variable voltage traction system is said to provide a high degree of manoeuvrability and Joy claims that this is complemented by the fact that the 17CM is 600 mm shorter than its nearest rivals. The AC drive has a high power density, allowing Joy to lower the chassis height making the 17CM more compact and this latter feature is important, as the machine is designed for seam thicknesses from 810-1010 mm,
The 14CM9AA is slightly larger than the 17CM and is intended for seam thicknesses from 910-1210 mm. With its thin-line gathering head and high power density cutter head, the 14CM9AA model is said to have unmatched load ability for this seam height (Long-Airdox or Tamrock Voest Alpine might disagree). Five of the 14CM9AAs are already being used and Joy reports that several more are also on order.
The biggest of Joy’s new continuous miners is the 12CM27, a high production 82.5 tonner which has replaced the previous 12CM12 model. According to Joy, the 12CM27 can load a 14.5 tonne payload shuttle car in 12-15 seconds because it is more powerful than previous models. This machine has been heavily-built to cope with the high production output and offers a minimum cutting height of 1.57 m. Like its CM-Series siblings, access for maintenance in the 12CM27 is said to be good while downtime has been minimised, As a result of these design improvements, Joy claims that these three machines offer customers a better cost per tonne ratio due to their low running costs and maintenenance requirements as well as their increased productivity.
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