Automated operations are winning over today’s mining industry. Whether it is autonomous trucks, tele-operated drills and blasts or automated logistics applications, mines are increasingly introducing these kinds of equipment and solutions, partly to better their Health and Safety performance indicators, but mainly to attract and retain highly skilled workers.
Attracting and retaining labour during the boom years was, indeed, what initially motivated Rio Tinto to go after what they call “the mine of the future” concept. During the boom years it was particularly difficult for companies to hire qualified people to work in remote locations and to deal with the increasing costs of moving them there. That is why, in early 2008, Rio Tinto unveiled its plan to introduce unprecedented levels of automation and remote operations to revolutionize the way mining had been conducted for more than 100 years. Competitors and partners soon followed and today it is hard to find a company that is not committed to making fully automated mine-to-port operations an industry standard.
The idea of automation is not a new one. A variety of approaches to autonomous underground navigation has been used with varying degrees of success around the world over the years, although all have relied on the installation of some form of additional infrastructure to guide the vehicle.
Systems based on external physical guidance – such as light ropes, inductive wires or reflective tape – have a number of serious drawbacks, principally the difficulty and expense of guide installation, maintenance costs and inherent inflexibility.
Their most important limitation, however, is the fact that none permit high-speed operation. With a driver on board, speeds of 20km/h to 30km/h can be achieved; the older generation of navigational systems seldom provides more than a fraction of this, since they all have limited ability to look ahead, being able to respond only to the guidelines in their immediate vicinity.
In addition, none of the older systems offer obstacle detection – an obvious weakness in often changing and unpredictable underground conditions. The latest wave of solutions relies on robust automation systems and innovative software applications to provide full functionality, while removing the driver from the cab.
Most of these limitations have been overcome by the new generation of mining trucks. Today’s mining industry is just as modern as the space program. In fact, Caterpillar’s 797 mining truck has more computer power onboard than the first Space Shuttle. Besides, the modern mining operations centre is more sophisticated than was Mission Control during the Mercury manned spaceflight program.
Electric or Mechanical?
“Mechanical” is the answer to this question, say experts at Caterpillar. The company is quickly moving forward with the new large mining trucks showcased at the latest MINExpo, which represent the company’s largest investment ever in new mining technology. Having been the lone exponent of mechanical drive trucks ever since it went into the manufacture of large mining trucks in 1984, Caterpillar has developed two electric drive trucks.
However, further development of the 793F AC electric drive truck has been suspended because it has no real advantage over the 793F with mechanical drive. The electric unit is heavier than its mechanical drive counterpart, which means that it moves less material and therefore has a higher cost per tonne. While on the flat the electric unit can reach a speed that is 5 km/h faster than the mechanical truck, Caterpillar believes that this does not compensate for the extra weight and can result in safety and tyre wear problems.
Caterpillar’s testing has proven its long-held mechanical drive position. According to David Rea, Global Mining Division manager, Caterpillar is of the opinion that mechanical drive trucks are the best solution. “Mechanical drive still offers the best powertrain efficiency. Less power is required to travel at the same speed. Thus fuel consumption is lower and mechanical drive offers a better emissions footprint,” he says.
Nevertheless, development of the 795F continues because there is significant interest in this machine as it gives those that want electric drive the option to choose it and because it neatly fills a capacity gap in the Cat product line.
The first 795F AC drive is on trial in a copper operation and more field-follow units are to go out to mines soon. Along with the expansion of field validation, Caterpillar will prepare this model for production. Caterpillar engineers have been testing two 795F AC prototypes, including the truck shown at MINExpo 2008, at the Tucson Proving Grounds.
The development program has provided input for the construction of the new 795F AC in Decatur, Illinois, that has been shipped to a copper mine in North America where it will serve as the first field-follow 795F AC as it works at the mine. The 313-t-capacity 795F AC is a new size class for Caterpillar and, as a result, the primary focus of the Caterpillar AC electric program has been on the 795F AC. The commercial launch date will be defined as the field-follow program progresses.
In mechanical drive, the 793F and the 797F have accumulated more than 75,000 hours of field testing and have proven their performance capabilities and their durability. The new Cat C175 engine that powers them has racked up 130,000 hours of field testing in mining trucks and more than 120,000 hours in power systems. Because of the success of these field-follow programs, the 793F is targeted to go into full production within a few months and the 797F late this year.
The new Cat trucks offer innovative designs for improved safety and performance. “All of the F-Series mining trucks incorporate innovative design and engineering that enables them to deliver lowest cost per tonne,” explains Ed McCord, Mining Truck Product Manager. “With the latest technology in AC electric drives now available, Caterpillar is able to offer both types of drive to the mining industry. We see the addition of electric mining trucks as a complement to our mechanical drive trucks.”
The most evident new component is the Cat C175 diesel engine, which is the power plant for each of the new trucks. The C175 meets US EPA Tier 2 emissions standards, yet it delivers 2,983 kW in the 20-cylinder version that powers the 363-t capacity 797F. The 16-cylinder C175 powers the 795F AC with 2,535 kW, and it powers the 793F, which has a 227-t capacity, with 1,976 kW. The C175 promises longer life between rebuilds, lower sound levels, improved altitude capability and improved fuel consumption compared to the 3500 Series engines it replaces. However, for those using that engine in older trucks, development continues.
As a brand new platform, the 795F AC incorporates new technologies throughout. For example, four-corner blended braking and retarding-using Cat oil immersed and cooled disc brakes, as well as electrical retarding, enhances safety and operator confidence. The remote-mounted generator enables servicing without the removal of other major components, and the wheel motors mounted inside the axle enable easy and separate servicing of the final drives. The retarding grids are radial, which promotes more uniform air flow for better reliability. And the Cat proprietary drive system is fully integrated and fully supported by Caterpillar.
Komatsu Driverless Frontrunner
Komatsu’s Autonomous Haulage System (AHS) allows for unmanned operations of multiple super-large dump trucks. AHS can improve the safety and productivity levels of mining operations while lowering overall costs and enhancing environment-friendliness for customers.
A fleet control centre monitors dump trucks featuring high-precision global positioning systems (GPS) and autonomous running functions akin to those of a robot. The centre specifies the destination of each truck and, by receiving directions wirelessly, the vehicles run autonomously along targeted hauling courses at the proper speed.
At the site for loading ore, a dynamic course generating system known as a “path planner” is mounted on hydraulic excavators and other loading equipment, guiding the trucks to the location at which they are to be loaded. Information about the course is also transmitted to the site for dumping the ore, enabling the trucks to dump it at a designated location with certainty. Optimal fleet operations under the AHS enable customers to lower their maintenance costs, energy consumption and CO2 emissions.
According to Jeffrey J. Dawes, President, Mining Business Unit and Vice-President of the Autonomous Haulage Division at Komatsu, the main advantage of surface automation is a very obvious one: safety.
To ensure safety, the fleet control system prevents collisions with manned vehicles in the same operating area. Should another vehicle or a person happen to come within the vicinity of an autonomous dump truck as it is running, the sensor for obstacles will activate and the vehicle will come to an emergency stop.
“Not having truck drivers automatically reduces the risk of accidents and other hazards. There is also a utilization advantage as the trucks can work almost around the clock, stopping only for refuelling or maintenance,” Dawes says.
“For mines that are developed on the basis of autonomous operations, there are also significant mine-development cost savings and operational cost savings, such as tire costs, fuel consumption and maintenance costs, among others,” he adds.
In May last year, Komatsu’s AHS FrontRunner went into full-time operation at Rio Tinto’s West Angelas Mine’s East Pilbara operation, in Western Australia. This is the second deployment of the proprietary system following delivery of the first fleet to Codelco‘s copper mines in Chile and the company is expected to deliver new products this year and in 2012 as part of the role that they are playing in Rio Tinto’s “mine of the future” program, in Pilbara, Australia. This iron ore operation will eventually be a mouth-to-port facility, with driverless trains and trucks controlled from 1,300 kilometres away.
Caterpillar’s Autonomous Answer
Although introduced to limited markets in 2003, the next generation of Caterpillar’s underground semi-autonomous system, MINEGEM, will be commercially available to North American, Latin American and Australian markets early this year and to European markets by the end of 2010.
MINEGEM is designed to enhance safety and boost operator efficiency and effectiveness in underground mining operations. The system can also have a significant impact through increased machine availability, decreased operating costs and extended machine life. MINEGEM is Caterpillar’s first commercially available semi-autonomous system and it completes one important element of the company’s strategy to develop a suite of autonomous mining systems that address mining companies’ business needs.
The system allows the operator to work from a safe and ergonomic work station far from the LHD (Load Haul Dump), either on the surface or underground, without sacrificing machine productivity. Studies have shown the productivity of a MINEGEM equipped LHD operated remotely to be significantly more productive than tele-remote or line-of-sight systems. Utilization is increased and significant time savings achieved because the operator does not have to travel from the surface to the machine.
It also boosts productivity by operating in second gear, compared to first gear operation for tele-remote and line-of-sight systems. During the load-haul-dump cycle, the operator, based in a remotely located control station loads and dumps the material under tele-remote control. The system then enables the machine to autonomously steer during hauling, preventing the LHD from hitting drivewalls. This is done using a combination of on-board computers, cameras, lasers and operator station software.
The latest version of MINEGEM enhances mine site safety with the inclusion of the Area Isolation System. Access restrictions are maintained by barrier control panels located at each entrance to the operations area. If the machine leaves the operations area or personnel enters the restricted area, the MINEGEM equipped machine will shut down. Additionally, zones can be configured within the operations area to automatically regulate machine speed and to establish “no go” areas at required points.
LADAR, a laser detection and ranging system located on the front and rear of the machine, provides spatial information about the loader’s location to the remote operator. Similarly, the cameras provide real-time video to the remote operator. These components allow for good visualization of the work environment, enabling the operator to be highly accurate and efficient.
Caterpillar has also ventured into the software market with solutions such as MineStar FleetCommander, a comprehensive surface mine monitoring and control system that uses technology to improve productivity and lower costs. Real-time interaction with mobile field equipment allows mine managers to improve machine utilization, manage operators, track material movement and monitor production in near real-time.
FleetCommander has proven its value in mines worldwide. Operations that switched from manual control to FleetCommander typically have experienced a 10 to 15 percent productivity improvement. One mine implemented FleetCommander for managing its shift change process and gained 15 truck loads per shovel each shift. MineStar FleetCommander 3.0 builds on proven results and delivers an additional 5 percent productivity improvement compared to previous versions.
Another of Caterpillar’s innovations is the AQUILA Drill and Dragline Systems. This is a scalable system designed to increase drilling accuracy and efficiency. It does not require the operator’s input to calculate levelling, rod-handling, hole cleaning or re-drilling and takes the guesswork out of staking to ensure holes are drilled to the designed pattern.
What else is next?
Christoph Mueller, managing director of DM Technologies GmbH&Co says that mining operations have a high potential of unused productivity lost by “trivial” things such as organization, logistics and operational management. He is not as keen on mechanization and automation as he is on changing the current focus.
“Going from mechanization and automation towards optimizing the overall mining process will unleash another big potential for cost cutting and for enhancing efficiency of production. Optimizing an overall process is a task of much higher total complexity compared to an isolated machine automation focus,” he says.
Mueller adds that successful process integration requires the collaboration of machine vendors, infrastructure suppliers, IT services and the mine itself. It also calls for a number of important preconditions to be fulfilled, such as: integrated IT systems with seamless interfaces between all components and peripherals involved; real time information access in all locations, and real time overview of all operational aspects.
“A crucial aspect for all of these issues is a seamless communication both above and under ground and IT interfaces which are easy and price-efficient to implement,” he says.
He concludes that there are ways to achieve productivity gains by process optimization and he predicts that the next big innovation wave in the mining industry will be all about enabling cost efficient performance of mine process optimization projects.
Links and References
mine process optimization à November Issue