Sandfire’s DeGrussa mine has always been focused on ramping up development and taking the operation to the next level.
The DeGrussa Copper-Gold Mine has set a rapid pace—moving from discovery in April 2009 to the completion of project construction in 2012.
But it’s not just the mine itself striding forward, with its contractors also making an impact in terms of technological advancements.
Byrnecut, Australia’s largest underground mining contractor, has racked up years of experience applying Cat semi-autonomous LHD technology.
The company’s mining team put that experience to use in Western Australia as they deployed Command for underground in Sandfire Resource’s DeGrussa Copper-Gold Mine, with the objective of boosting productivity and driving down costs.
In March 2014 Sandfire Resources determined that it would seek tenders for the DeGrussa underground mining work, which had been performed by another contractor during the three years the young underground mine was being developed.
Byrnecut worked with Caterpillar and WesTrac, the Cat Dealer in Western Australia, to submit a proposal differentiated by semi-autonomous mining technology.
It caught Sandfire’s attention, as they awarded Byrnecut the contract on June 20 with start-up on July 1.
“We had a tight time frame to mobilise and start working at DeGrussa,” Pat Boniwell, Byrnecut’s director, said.
“Caterpillar and WesTrac were engaged early, during the planning phase; we had to have a strong commitment to ensure early delivery of the mining equipment. Detailed planning to reduce delays and disruption was critical to success, as was communication and teamwork during mobilization,” he said.
The machinery delivered to DeGrussa included six AD60 trucks, one R3000H LHD, two R2900G LHDs and three Command for underground automation systems, which included three mobile operator stations.
“We were excited about the proposition of an all Cat fleet at DeGrussa,” said Ed Mort, Caterpillar Account Manager. “A lot of the incremental improvements in the new AD60 trucks, R2900G and R3000H loaders were from key customers like Byrnecut. It also gave us the opportunity to leverage the integrated technology on these new models for machine health monitoring and payload management.”
“We’ve had a long and productive relationship with Byrnecut,” Colin George, Caterpillar’s account manager, said, commenting on a relationship that has been ongoing since before Cat acquired Elphinstone Underground in Burnie, Tasmania
“They are early adopters and drive innovation in the industry through their contracts and by working with equipment manufacturers like Caterpillar.”
Boniwell listed the reasons for using Command for underground: “We can use larger loaders in the same size drive with no damage caused by contact with the drive walls—which is a problem when tramming via tele-remote. Production is largely driven by loader size and speed, and autonomous tramming allows both. Command also allows us to use the dead time during blasting, which can be one or two hours because miners have to exit the mine. We can’t do that with a simple tele-remote system, but we’ve been successfully doing this for years with Command.”
Operating LHDs by tele-remote when tramming results in significantly increased maintenance costs due to collisions with the drive walls; the accurate sensing and guidance system of Command for underground eliminates contact with drive walls when tramming autonomously.
One of the remote operator stations for the LHDs is located on the surface and connected to the equipment via fiber optic cable. The surface location provides safe and easy access for shift changes, as the operator does not have to travel underground to start a shift or potentially face a hotseat changeover. The other two operator stations are mobile and can be moved to the appropriate production level.
Across the entire operation Byrnecut mobilised 30 pieces of mining equipment and 150 people. It used a high percentage of the existing workforce as well as its own employees who had experience with Command for underground. Those experienced personnel ensured that proper procedures were instituted quickly while also touting the benefits of semi-autonomous LHD operation.
As a result LHDs were up and operating via remote from the surface within two weeks of contract start-up.
“Experience allowed us to do this,” George said.
In addition to bringing experience to the project, Byrnecut, WesTrac and Caterpillar developed a framework for dealing with any problems during the delivery, commissioning and early operation of the machines and automation systems; all three working together to identify problems early and plan around those issues. Collaboration was another key to success.
In practice, the WesTrac support team remained on site for about three months.
“The field services team made our job easy,” Max Woods, group plant manager for Byrnecut, said.
“They allowed us to focus on other things.”
By the end of the first three months of operation, production was back up to the previous levels.
“It was a well-run mobilisation,” Woods said.
“We reached the full production rate very quickly, and consistency has been good month-in and month-out. That’s impressive considering that we had not previously brought new loaders with new technology to a new job.”
Now the fleet moves around 180,000 tonnes of ore and waste monthly.
The underground mine plan itself includes more than 38 kilometers of lateral development, providing access for simultaneous extraction of ore from multiple faces on multiple lenses. Four different deposits provide production flexibility.
Byrnecut is working with a 5.5-meter-wide decline and 4.5- to 4.7-meter-wide level development. The open-stope mining plan includes paste fill of the primary stope before mining the adjacent secondary stope. Byrnecut managers point out that safety in open stope mining requires them to rely on remote control technologies. At least 60 per cent of the material is handled by the semi-autonomous loaders.
The semi-autonomous LHDs muck from production stopes and carry material to stockpiles.
That material is subsequently loaded onto trucks by other LHDs.
Because of a long truck haul of four kilometers and Byrnecut’s emphasis on productivity, the company looks closely at such things as speed on grade and optimum payloads. Cat machine technologies such as lockup torque converters—on both LHDs and trucks—and payload indicating systems contribute to higher productivity, according to operations managers.
“The addition of the lockup clutch torque converter on the R2900G has been a great product improvement for our applications,” Woods said.
“Good speed on grade is especially critical when doing decline development work.”
Byrnecut emphasised optimising truck payloads to achieve the high productivity. The Cat payload indicating system has been useful at DeGrussa. Because waste weighs only two-thirds of the same volume of ore it’s difficult for operators to assess weight of material visually as such payload indicating on the trucks has been most useful.
“Increases in productivity go to the bottom line,” concluded Boniwell. “Technologies such as Command are not inexpensive, but we can get huge increases in productivity. We will continue to adopt technologies that bring good returns in the form of increased productivity.”