MANITOBA - Sustainability is achieved when the least amount of energy exerted results in the greatest productivity outcome. This philosophy is key to the management at HudBay Mineral's Chisel North zinc mine near Snow Lake. The company decided to reduce its fleet size and all the energy it takes to make it operational, boosting productivity with a larger underground haul truck.
The mine has been operating with multiple Atlas Copco MT5020, 50-tonne trucks. By going to a single, larger-capacity MT6020, 60-tonne truck, the production goal is reached with fewer trips in a day. This equates to reduced fuel and manpower costs and less wear on equipment.
Atlas Copco's MT6020 is one of the newest additions to the market. There is no underground mine truck that can match its hauling speed at its capacity, according to the manufacturer. At Chisel North the MT6020 has been successfully used mostly for ore haulage. With its heavier specific gravity, zinc ore results in less than a full volume load, but the truck's deeper bed compensates by allowing a greater load capacity for hauling waste.
The goal of the mine is to haul 950 t/d. Randy Cockle, who is responsible for mine operations, likes the boost in productivity he gets from the Atlas Copco MT6020. "I gain two loads at the end of the day-that's more [material] with less [expense]," he said.
The mine's current ramp is 5.2 km long with a vertical depth of 670 metres and has grades up to 15%. On the steepest grades, the MT6020 can reach climbing speeds of 14 km/h fourth gear. The average speed is better, 11 to 12 km/h. The average cycle time is 47 to 50 minutes with the MT6020.
Mine manager Bob Libby also noted the importance of these savings, saying, "Fewer loads means less manpower, fuel, and maintenance - it all adds up."
The zinc ore has a specific gravity of 3 to 3.2 in situ, which is 4% to 50% more dense than the waste material. Operator Ron Spruyt says a zinc rock the size of a soccer ball is more than an average man can lift. So it's important to know when the capacity is reached during loading.
The mine rear-loads the truck with an Atlas Copco ST14 load-haul-dumper. The task is made more precise by the weight readout on the truck. This helps to prevent accidental overloading, which not only could damage the truck but also makes for quicker, more decisive cycle times, eliminating any second-guessing.
The MT6020's conveniences don't end with its on-board scales. The operators all agree that the comfort of the truck is greater due to features like the suspension system and automatic transmission. If the operator chooses, he can shift the transmission manually when conditions require it.
Truck operators Ron Spruyt, Darwin Spenser and Ryan Erickson, who have been trained on the MT6020, find it's a very comfortable truck to run. These men are also cross-trained to run loaders and other mining equipment, which makes the mine even more efficient by utilizing manpower wherever necessary.
Atlas Copco's trainer and lead technician on location, Joe Benoit, has been training the operators on the features of the MT6020. Having an expert trainer work with experienced operators has also presented the opportunity to highlight features that can help with efficiencies. For example, the transmission's manual override feature will downshift to keep the speed even. "Most of the time the automatic transmission will take care of shifting, but it's the steeper section of the ramp where a manual shift is a handy option," said Benoit.
Bob Libby talked very highly of the efficiency and reduced costs that come with the MT6020, but he said it's the service that really stands out. "From the support onsite right through to the warehouse people, Atlas Copco's service is top-notch. As for Joe, he's always there when we need him, day or night. He's a great guy to get the job done and he doesn't stop until it's finished."
According to Randy Cockle, the plan at the mine is to use the MT6020 to take care of the bulk of the ore. Using one ore truck has made operations run smoother for the mine while cutting down on expenses. As long as the equipment keeps running as it has been, Libby believes they can achieve their haul goals by running 18 loads a day. "Day in and day out, just keep doing what you say you can do," said Libby. And isn't that the definition of sustainability?"
This item was supplied by Atlas Copco. Please visit the website at www.AtlasCopco.com.