Three companies talk to North American Mining about recent developments to improve load-and-haul operations.
By Jonathan Rowland
Trucks, loaders, shovels, dozers: this is the equipment – the Big Iron – that has come to define our view of opencast mining operations. Yet traditional load and haul operations are coming under increasing and competing pressures. Strip volumes rise as mining companies exploit deeper and more complex ore bodies to feed the world’s growing demand for metals and minerals. At the same time, mining companies are committing to more sustainable mining practices, including lowering their carbon emissions. Companies involved in the load-and-haul ecosystem are developing solutions to square this circle. Three gave North American Mining the lowdown on some of their latest innovations.
The load-and-haul OEM
“The quest for increased loading efficiency is never-ending,” said Caterpillar in a recent release. Truck and loading equipment OEMs are responding by pushing “the envelope of machine design and leveraging the latest technologies to increase wheel loader efficiency and payload while using less fuel to drive down the cost-per-ton of material moved.” The recently commercialized Cat 995 wheel loader and next-generation 785, 789 and 793 trucks are cases in point.
Pushing the envelope of loader productivity and efficiency
The same size as its predecessor, the 994K, the 995 wheel loader offers a higher-rated payload and bucket capacity range of 17.2 to 43.6 cubic meters (22.3 to 57 cubic yards). The result is an up to one pass reduction in the loading cycle compared to the 994K when loading Cat 785, 789, and 793 trucks, delivering “up to 33% increased production and efficiency for mining operations when loading 785 trucks, up to 25% when loading 789 trucks, and up to 20% with 793 trucks,” the company said. “Specifically, when loading 240-tonne (265-ton) trucks, the 995 wheel loader delivered 21% higher efficiency and 24% more production than its predecessor in equal operation mode because of the higher-rated payload and 6% increase in hydraulic force.”
These benefits have been delivered “through upgrades to machine design alone,” Caterpillar added. “Newer technologies integrated with loader electronics are being introduced to further boost machine and operator productivity.” These new technologies “can also assist in reducing stresses on machine components to increase longevity” and include the following:
- Tire slip prevention automatically reduces rimpull when the tire is under less downforce and increases rimpull with more downforce, supplying maximum rimpull when needed. Tire set detects contact with the pile and automatically lifts against the pile to set the tires and increase available traction, discouraging premature racking and increasing usable rimpull.
- Another way to improve loader productivity and efficiency is to keep the lift motion without excessively using the impeller
clutch. The 995 wheel loader’s standard lift stall prevention feature automatically applies the impeller clutch when necessary to prevent hydraulic stall when lifting through the face. Combined with tire slip prevention, this fully automates the impeller clutch while digging, allowing for bucket fill without using the pedal impeller clutch. - Onboard operator coaching measures highlight individual operator behaviors that impact efficiency, production, and
component life. The techniques monitored include tire rotation reduction, unracking in-dig, leveling the bucket when entering the pile, excessive impeller clutch usage, dump height, and kickout usage. Instructional videos provide training on these measured behaviors, showing incorrect and recommended behaviors.
Selecting a large enough bucket to achieve target pass-match loading of the truck across a range of material densities is also “critical to reaching productive targets,” according to the company. “Look for machines with payload overload prevention technology to help give operators the confidence to use a large bucket without the risk of overload. Adjustable overload values based on target payload configure overload prevention to stop or slow the lift arms when the loader exceeds the established overload value.”
Under the hood, the 995 wheel loader engine offers idle shutdown, on-demand throttle, and enhanced economy modes. “Saving up to 8% fuel per hour and improving efficiency by up to 5% compared to horsepower plus operation, on-demand throttle on the 995 allows operators to maintain normal operation with the left pedal and implemens, while the machine manages engine speed,” Caterpillar explained. “The enhanced economy mode offers up to 8% greater efficiency and up to 13% lower fuel consumption per hour than horsepower plus. Compared to the 994K’s throttle lock operating mode, the enhanced economy mode has demonstrated a 30% increase in efficiency and an 11% reduction in hourly fuel consumption, translating to 23% less CO2 per unit of material moved.”
The hydraulic system’s optimized pump control boosts efficiency with its positive flow control system. “Hydraulic oil flow is proportionate to implement lever movement, and four electronically controlled, variable piston pumps enable fast, productive cycles,” the company explained. “The system increases bucket feel and control while delivering consistent performance and efficiency with lower system heat.”
Improving productivity with the next generation of trucks
The next-generation Caterpillar 125 to 240 tonne (150 to 260 ton) productivity class mining trucks – the Cat 785, 789 and 793 – feature “a flexible technology platform and optional configurations to help each mining operation meet their goals,” David Rea, general manager of Cat Mining Trucks, told North American Mining. These include several new or improved features focused “on improving productivity and efficiency, including a new cab design, enhanced connectivity, and operator support systems.”
The next-generation cab is “built for operator comfort and efficiency, lowering noise levels and accommodating a wider range of operators,” explained Rob Shea, Cat 793 product applications specialist. “The cabs also come with two 10-inch screens as standard to reduce clutter, with one replacing the traditional dash cluster behind the steering wheels and a secondary display located to the right of the steering wheel. These screens provide a much larger array of information, tailored to the application’s needs at the time, from machine data to electronic operating and maintenance manuals.”
The Truck Payload Measurement System II (TPMS II) “leverages the trucks’ more powerful electronic control module (ECM) and faster data transfer, plus its onboard inertial measurement unit (IMU), to improve payload measurement accuracy,” continued Shea. “TPMS II measurements are taken under the loading tool and throughout the haul, calculating load placement bias to enhance payload accuracy and reduce errors by roughly 50%. All data is remotely accessible through the truck’s telematics.”
Operator speed coaching tells the operator if they are running at optimum speed or leaving some room for improvement. “The system maximizes asset performance by giving the truck’s ideal speed range, elevating the skill level of all operators,” Shea said. “It provides resistive braking and propulsion guidance capabilities based on payload, grade, operating conditions, and machine performance history. In resistive braking conditions, the green range on the speedometer displays the top speed of short-distance deceleration capability of grades less than 450-meters long, while the low point is for continuous grades longer than 1500 meters. In propel, speed coaching provides a green carrot and target speed.”
Finally, the AutoHoist feature “simplifies body dumping to help provide lower cycle time,” concluded Shea. “Integrated with the transmission control, it consolidates four continuous operator hand and foot inputs into two simple hand inputs. It can thus reduce typical dump cycle times in some instances by up to 12 seconds and potentially reduces fuel burn during the cycle.”
The GET and truck bodies supplier
Load and haul fleets “need to be evaluated in their totality, rather than focusing on one portion of the overall process,” Andrew Dillion, global products manager for Underground LHD and Truck Bodies at Weir – ESCO Division, told North American Mining. “To drive efficiencies, shovels, loaders, and trucks must be built to move a mine’s specific material and match maintenance intervals to maximize machine uptime, requiring suppliers to collaborate with mines to deliver optimal solutions.”
ESCO UltraHaul truck bodies are an example of this approach. “We engineer UltraHaul bodies according to site-specific material conditions and loading tools for optimal payloads and fuel efficiency, incorporating several features that help deliver optimal performance,” explained Dillion. “Curved sidewalls require less bucket lift during loading, reducing fuel consumption and cycle times; a wider target area provides easier loading and improved material retention; and curved rear tail reduces load spillage during travel. The floor-to-sidewall transitions are also curved to enhance material flow during dumping to reduce carry-back, and a curved tail ejects material over the berm to minimize material build-up in front that will interfere with the truck body tail.”
ESCO UltraLight truck bodies offer an additional performance boost.
“These truck bodies incorporate special alloys and manufacturing technologies to use less steel, producing a lighter-weight truck body that can haul more ore per trip, reducing fuel consumption while improving productivity,” added Dillion.
When it comes to loading equipment, the ESCO Nexsys lip system and GET for rope shovel dippers “reduce downtime for longer uninterrupted shovel operation by significantly lowering lip maintenance and extending tooth and adapter life,” said Yesenia Meraz-Torres, global product manager for Mining Expendables at Weir – ESCO Division.
According to Meraz-Torres, the next-generation lip system features a slimmer profile for better penetration and loading with up to 10% less system weight than previous systems. It also offers reduced rebuild requirements, improved adapter protection, excellent durability, and fewer point changes, leading to more production, lower maintenance, and less unplanned downtime. “With this new, innovative, and highly engineered system, mine sites can extend the campaign cycles, greatly improving overall productivity,” concluded the Weir – ESCO Division expert.
Lastly, improved data collection and analysis technologies, such as Motion Metrics ShovelMetrics and TruckMetrics, allow mines to “evaluate their current production and make data-driven decisions on the products needed to optimize their production and control costs,” noted Dillion. “For example, TruckMetrics provides load profile and volume monitoring, helping to prevent uneven truck wear and accurate load profiling, optimizing production. This drives deeper collaborations between us and our customers to customize our mining buckets and truck bodies to focus on a miner’s critical metrics.”
An alternative perspective
Despite their long history as a practical and flexible mining method, conventional truck and loader operations “may be reaching an upper limit when it comes to economic and sustainable operations,” argued Chris Pearson, group business development manager at MMD, one of the leading suppliers of in-pit crushing and conveying (IPCC) solutions to the global mining industry. IPCC offers an alternative but “is not suited to every scenario; however, technology that bridges the gap between IPCC and traditional truck-and-shovel methods could unlock potential for mine operators to improve productivity.”
MMD’s Fully Mobile Surge Loader (FMSL) aims to do just this. A “first of its kind,” according to Pearson, the FMSL “has the potential to take conventional truck-based operations to the next level, delivering an up to 40% improvement in productivity. It achieves this by de-coupling the shovel from the truck, enabling the shovel to load continuously, thus unlocking its full production potential.”
“Traditional truck-and-shovel operations incur wasted hanging and spotting time,” explained Pearson. “Operating between the shovel and trucks, the FMSL’s consistent hopper position and generous target area allow the shovel operator to dig, swing, and dump more quickly and continuously without the pressure of truck fill factors, payload accuracy, or material spillage. “Couple this with replacing the potentially hazardous truck reversing maneuvers in the loading area with a simple and guided ‘drive-thru’ operation, and the process immediately becomes much safer, faster, and more efficient.”
“Furthermore, by distancing trucks from the shovel, the FMSL reduces the risk of tire damage from boulders and spillage,” Pearson added. “The loading process is gentler and more controlled, which may allow for lighter-weight truck body designs thus improving the payload to gross truck weight ratio. Using an FMSL also eliminates the need to match the shovel to the truck fleet, allowing miners to expand their haulage fleets with different-sized trucks.” This last feature may facilitate so-called ‘swarm mining’ with a fleet of small trucks that combines the flexibility of a truck conveyor system with the performance of a conveyor system.
On the truck side, the FMSL “significantly reduces payload variance, eliminating the detrimental impact of overloading on haulage costs, greenhouse gas emissions, fleet productivity, and clean-up costs,” Pearson continued. “The FMSL delivers within 2% of the target payload every time, benefiting the truck fleet’s operation, wear, and maintenance.” Tighter loading control may also ease the adoption of alternative power sources, such as batteries or hydrogen, which are particularly sensitive to payload variance.
Finally, the FMSL is a convenient platform for other productivity and efficiency-enhancing technologies like bulk ore analysis. “The consistent material stream delivered by the FMSL can be safely, accurately, and comprehensively scanned and analyzed,” said Pearson.
“Scanning ore so close to the working face retains material heterogeneity and enhances ore body granularity and control, improving our understanding of the ore grade and material composition that enters each truck. This allows mines to determine ore grades during the truck loading process, sorting and directing high-grade ore to the processing plant, sending ore close to the cut-off grade to a bulk sort recovery system for separating ore from waste, and dumping materials classified as waste.”
“Mine operators are increasingly looking to industry innovators to extract finite resources sustainably,” concluded MMD’s Pearson. “These are challenging but exciting times, where we must strip back and rebuild how we think about mining processes.”
Load and haul fleets need to be evaluated in their totality, rather than focusing on one portion of the overall process.