It’s ironic that as modern surface mining burrows further into the ground, whether at new projects that exploit deeper, more complex deposits or at mature mines that are simply digging deeper in place, production efficiency depends more and more upon a clear view of the sky. Mines are increasingly relying on GPS-based machine location and high-precision surveying applications, and because these applications require accurate Real-time Kinematic (RTK) GPS position data, their reliable operation hinges largely on the ability to ‘see’ and track at least four GPS satellites at any given time—a situation that isn’t always possible when working at certain locations in deep open-pit mines.
To overcome this problem, mines over the past decade have turned to pseudolite systems; i.e., ground-based transmitters of GPS-like signals that enhance GPS satellite ‘geometry’ and even replace the GPS satellite constellation in some situations. However, pseudolite-based systems are not completely free of technical problems that can inhibit their performance under certain conditions. Various companies have pursued ways to improve pseudolite performance, but recently Leica Geosystems Mining announced an exclusive industry partnership with Australia-based Locata Corp. to provide the mining industry with what is described as the only high-precision radio positioning system that is not reliant on pseudolite concepts.
In fact, Locata’s technical literature emphasizes that its ‘Locatalite’ units are not pseudolites. As explained by Locata, pseudolites do not synchronize to each other, which is a critical requirement for the creation of a radio-positioning system. Atomic clocks in GPS satellites are used to achieve this. However, the LocataLite transmitters can accomplish synchronization without input from these clocks. Within minutes of being turned on, LocataLites generate an autonomous, nanosecond-accurate positioning network through a new synchronization process called TimeLoc.
Locata says its proprietary TimeLoc signals are different from GPS satellite signals, and the Locata system architecture is designed to create a ground-based positioning system that is a true GPS replica—a one-way ranging system providing pseudorange and carrier-phase measurements from a network of synchronized transmitters.
Part of the Package
Under the Leica/Locata partnership, Leica Geosystems Mining will provide this new technology, called Leica Jigsaw Positioning System (Jps), as a part of its Jigsaw product suite. Leica’s Jps, according to the company, sees LocataLites as a ‘constellation’ of ground-based satellites or alternative points of reference that can be used in conjunction with, or completely independent of, the GPS satellite network. A mine, instead of relying solely on GPS satellites, can maintain availability and accuracy by using the Leica Jps alternative reference points in combination with any available GPS satellites. LocataLites can be permanently positioned on site or moved at will—and the Locata network even can be deployed completely independent of any GPS network, using only the LocataLites as points of reference.
After partnering with Leica Geosystems in 2008 to participate in development of the Locatalite technology, Newmont Mining Corp.’s Boddington gold mine in Western Australia installed the first fully integrated (GNSS+Locata) receivers in March 2012 to improve performance of the mine’s fleet of drill rigs. It has since reported that drill rig up-time and efficiency improved dramatically after the Jps system was commissioned.
Dr. Brendon Lilly and Stuart Gray of Leica Geosystems, collaborating with the Locata team and John Carr and James Earl from Boddington, authored a report released in August 2012 describing the Leica Jps components and their deployment at the mine. As explained by the authors, the installation comprises two main components: the Jps Locata-Lites, which are the transmitters positioned around the mine pit; and the Jps receivers mounted on the machines.
The Jps LocataNet is the “local constellation” network made up of a number of Jps LocataLites. In this network, one of the Jps LocataLites is assigned Master status and the rest are assigned as slaves. The slaves ‘TimeLoc’ to the Master. The Master also contains a meteorology station that measures and transmits pressure, temperature and humidity data around the LocataNet so that it can be used in positioning computations.
The paper noted that, although the GNSS satellite constellations and the Jps LocataNet have extremely accurate, yet independent time bases, it is far more convenient for the integration of GNSS+Locata combined positioning solutions if the time bases of each system are closely aligned. Locata developed a method to slew its internal time base to precisely align with the GNSS timebase (and hence the global-standard UTC time). When temporal alignment is achieved, the combined solution algorithm does not have to correct for the time offsets between systems. Leica Geosystems has integrated this capability into the Jps LocataNet and Jps receivers, allowing the complete Jps LocataNet to synchronize with GPS time, while both GNSS and Locata signals measured at the Jps receiver are synchronous. Consequently all signals can be used directly and simultaneously in position calculations.
The authors point out that as with any other transmitter used in a GNSS-style network, each transmit antenna attached to a Jps LocataLite must be accurately surveyed. Any traditional survey method can be used, but for convenience LocataLites are designed to autonomously “self-survey” without any surveyor input. Each Jps LocataLite has a built-in GNSS RTK receiver and the Jps tower has a GNSS antenna. When turned on, the Jps LocataLite self-surveys the position of the Jps tower automatically and continuously monitors any movement of the Jps tower (e.g., from subsidence or blasting). This allows the Jps LocataLite to be positioned in active mining areas and be relocated quickly when required. If RTK positions cannot be computed for the self-survey, then the Jps tower can be manually surveyed and its position entered into the Jps LocataLite using its Web interface.
Based on the results gathered from testing the initial installation, the authors concluded that “the Leica Jigsaw Positioning System (Jps), powered by Locata, provides substantial improvements in positioning availability compared to normal RTK GNSS receivers, while maintaining RTK quality position accuracies. Leica’s Jps receiver is the world’s first commercial GNSS RTK receiver to use the new Locata signals for positioning, utilising the existing, mature positioning technologies developed by Leica Geosystems. The Leica Jps has been designed specifically as an OEM device and it can therefore be integrated easily into any high precision machine guidance system.
“The Jps LocataNet is capable of covering specific areas in a single pit or multiple pits on a mine site. If additional coverage is required, then the system can be scaled to meet the customer’s needs. By simply adding more Jps LocataLites to the area, or by moving the existing Jps LocataNet to a more appropriate configuration, the mine can ensure reliable and accurate positioning signals are always available where and when they are needed.”
More recently Dr. Lilly, who is product manager at Leica Geosystems Mining, stated: “Since deploying the Locata-powered Jps at Newmont Boddington Gold there has been an increase in operational machine guidance availability of almost 23%—from 75% up to 98%. Newmont Boddington Gold is so happy with the results that they have turned off their GPS-only solutions altogether, and now rely solely and successfully on Jps alone. They have already installed Jps on eleven drills and intend to equip their entire high-precision fleet.”
The Mining Solution
The Leica Geosystems/Locata partnership was announced as part of a global initiative Leica introduced at MINExpo 2012, in which the entire Leica Geosystems technology portfolio will be offered to the mining industry as a comprehensive mining solution.
As a part of the company’s mining solution, Leica said its GeoMos slope-stability monitoring software will be fully integrated with the Jmineops fleet management system. Pit slope stability alerts from the GeoMoS monitoring system will be routed in real-time to Jmineops. Each GeoMos monitoring project will be fully visible along with all other Jmineops data.
Also showcased alongside the GeoMos integration was an innovative UAV (unmanned aerial vehicle) resulting from a technology partnership between Leica Geosystems Mining and UAV developer SwissDrones. Specifically designed for the mining environment, Leica said the UAV can fly for up to four hours via line-of-site remote control. In the near future, the unit will be fully automated. Leica’s RCD30 medium format camera has been integrated into the SwissDrones Waran helicopter-style TC -1235 UAV to provide high-quality multispectral imagery and accuracy.
Weighing in on Equipment Total Cost of Ownership
Actronic Technology, the New Zealand-based developer of the Loadrite range of products for weighing wheel loader/ excavator buckets, conveyors and other applications, recently released a report on optimizing total cost of ownership on payload-carrying earthmoving equipment.
According to the company, while most equipment owners understand that total cost of ownership is more important than just the purchase price, many don’t realize that they could actively reduce their total cost of ownership across earthmoving equipment and trucks by using Loadrite’s monitoring and alert features to set benchmarks and measure productivity.
Total cost of ownership includes everything from the original purchase price to the daily running and maintenance costs, depreciation, finance and even ‘hidden’ costs like insurance and employee wages.
A machine that appears to be competitively priced may end up costing many thousands more than a higher priced machine because it may deliver lower productivity, increased fuel and maintenance costs and a lower resale value.
Total cost of ownership can be measured based on the number of hours a machine works, or based on actual productivity in terms of the amount of material moved. By basing total cost of ownership calculations on the amount of material moved, operators can get a clearer picture of the machine’s actual cost of ownership, since a machine that moves more material in less time is likely to generate more income as well as using less fuel per ton of material moved.
While it makes sense to choose a fuel efficient, highly productive machine, it is also possible for smart operators to proactively reduce the machine’s total cost of ownership by reducing the running costs, according to Loadrite Product Manager Elliot Chisholm.
There are a number of steps that can achieve this, such as improving efficiency to reduce fuel usage, optimizing the loading process and improving the maintenance scheduling so that all machines and vehicles are up and running when you need them to be.
“The first step is to understand how productive your machines are, including how much fuel they use and how much material they move,” Chisholm said. “The next step is using that information to make changes where necessary to improve efficiency and reduce costs.”
By tracking the amount of material moved per hour to measure productivity and set benchmarks, operators can see underperformance and make appropriate adjustments to ensure all equipment is working to its optimum efficiency.
An onboard weighing system like those offered by Loadrite can be used to calculate the weight of material in an excavator’s or loader’s bucket, relay this information to the operator and record the weight for later use.
“Being able to track the amount of material moved per hour can then be used internally as part of an overall business analysis to measure productivity and set benchmarks,” Chisholm said.
“Once you know your benchmark productivity rates, it’s also easy to identify equipment that is underperforming, which sets off a trigger for an investigation into the underlying causes. These causes can vary widely, from operator error to equipment failure.”
Once productivity benchmarks are set, fleet managers can customize the Loadrite system to capture a wide range of other data such as cycle times, which can then be used to identify process bottlenecks and inefficiencies. By resolving these issues, managers can improve productivity and reduce operating costs.
By tracking and monitoring various productivity indicators, managers can see variations and make changes that will result in a more efficient use of resources.
“Being able to track and monitor fuel use, for example, is a major consideration in assessing the cost of ownership, particularly given the high price of fuel. By understanding the amount of fuel used to move each ton of material, you can see how productive each machine is and possibly find ways to reduce fuel usage,” Chisholm said.
The Loadrite system can also measure the cycle times between each loading event, which can show how efficiently the material is being moved. Shorter cycle times generally point to a more efficient and therefore more profitable operation.”
The system actively helps reduce fuel use. By using an accurate on board weighing system, operators can ensure trucks are filled correctly the first time, with no productivity lost due to under loading or overloading.
“By loading trucks correctly from the outset, unnecessary truck movement is reduced as there’s no need to turn around for either a refill or a removal of material once the trucks get to the weighbridge,” Chisholm said.
Setting Maintenance Parameters
Being able to measure the time between replacing consumable parts, operators can establish the most efficient and convenient maintenance and replacement schedule. This can be done by measuring the amount of work done in terms of material moved, rather than simply by working hours.
“The system can record how much material has been moved since the last time the bucket edge was replaced, for example. This data would allow different brands to be benchmarked on how long they last, another critical factor in calculating the total cost of ownership,” Chisholm said.
“Tire damage on trucks can also be reduced. Providing accurate and consistent weight measurement from the outset allows operators to set the correct target weight for the loader bucket to accurately load the truck. Because the truck’s tires are inflated correctly to carry a certain weight, they can be damaged when carrying too much weight. So once the loader is set for optimal efficiency, you can potentially prolong the life of the tires.”
Chisholm said Loadrite’s onboard weighing system can be configured to provide the data needed for any operation. “Our distributors work with project managers to identify the configuration that will give them the information they need. We work with fleet managers individually to ensure the system meets the needs of their business. Our aim is to ensure the data collected provides real value to increase productivity and profitability over the lifecycle of the machine.”