A trustworthy conveyor drive was what Eloise Copper mine’s maintenance team were looking for when they consulted CBC’s experts in July last year.
As a mine site located in the regional Queensland town of Cloncurry, spare parts and technical support is not always on hand for Eloise Copper, so Maintenance Supervisor, Craig Stokes, says he didn’t want to take any risk with the new conveyor drive.
“We are a remote site, and we have limited access to spare parts. We just can’t hold everything on site so having something that’s reliable and is not going to fail is critical for us,” says Craig, who has been the mine’s maintenance supervisor for the past four years.
Despite being located more than 700 kilometres away from Cloncurry, CBC’s Townsville branch has been supporting Eloise Copper mine for nearly a decade, with CBC specialists often travelling to the site to offer their expertise in person.
Eloise Copper, operated by FMR Investments, feed 720,000 tonnes of ore into their mill and produce 50,000+ tonnes of copper concentrates per annum. Craig says the conveyor in question delivers material from the jaw crushers to the milling circuit to be grinded further.
“We were having some reliability issues with the existing hydraulic motor. The conveyor’s performance became intermittent when the material on it got wet and heavy during the rain. Having multiple valves and pumps in the hydraulic drive system made fault finding more complex.”
Once the maintenance team had made up their mind to replace the old hydraulic drive unit with a new unit, the CBC specialists’ recommendation was to change the hydraulic drive with an electric variable speed drive (VSD) geared motor for better reliability.
“An electric drive is a lot easier to maintain than a hydraulic drive,” says Sam Wilkinson, CBC’s Mining Manager for North Queensland. “That’s because there are fewer moving parts and components in an electric drive. Also, there’s no need to frequently change the hydraulic oil and oil filters, which further eliminates any potential risk of oil contamination. The electric drive is also more compact and it offers the same amount of torque across the entire speed range.”
To deliver the VSD controlled geared motor, the CBC team used their in-house engineering capabilities and worked with their premium partners at Bonfiglioli and TECO to assemble the unit with the right configuration.
A Bonfiglioli HD Series gearbox was identified as the ideal gearbox for Eloise Copper’s application. As Bonfiglioli Sales Manager, Alan Young, explains, Bonfiglioli HD Series gearboxes are specifically designed for the harsh working environments at mines.
“The Bonfiglioli HD Series gearboxes are designed based on the latest gearbox technology to ensure the longest service intervals. The robust design means the gearboxes can be easily customised and fitted with different cooling options and accessories. The output shaft can be chosen both in the parallel (HDP) or right angle (HDO) configuration to ensure minimum mounting space is required,” he explains.
Based on the information and dimensions provided by CBC engineers, the Bonfiglioli team also manufactured the base plate to mount the gear unit into the existing conveyor drive setup. They incorporated a cooling fan within the space confinement of the base plate.
The motor selected for the application was a TECO MAXe3 electric motor, which the TECO team equipped with a forced cooling option and delivered to CBC.
TECO MAXe3 Mining motors are an ideal choice for VSD driven mining applications due to their robust High Efficiency construction. They have superior inverter rated insulation, are IP66 and insulation class H as standard, and have a 1.2 service factor at 40°C.
As Sam explains, electric motors need to be equipped with forced cooling fans in slow-running applications.
“When you run an electric motor very slowly, it should always have a fan at the back because when the fan runs too slow, it may overheat. With electric motors, whenever you run them very slowly, you need to have a separate powered fan to keep them cool.”
Once all of the engineering work was finalised and the new VSD-controlled geared motor was put in place, the result was better than the maintenance team expected.
“The temperature in Cloncurry was around 48-degrees on the day we installed the new unit. That was a good test for us to make sure the new unit could meet the site’s requirements,” says Sam.
Craig says he was impressed with the outcome. Apart from the reduced downtime from having to regularly repair the hydraulic drive, the upgrade to a VSD motor has also saved the mine thousands of dollars through better control on the feeding rate.
“It was very important for us to be able to have consistent feed to the mill. The conveyor drive upgrade has provided us with improved control of mill densities and grind size.”
Eloise Copper has since decided to upgrade a second conveyor on the site with the same technology provided by CBC.
“We are very happy with the reliability and the operational consistency of our conveyor and we want the other conveyor to be as reliable as this one. The CBC team has been very helpful in working through the technical requirements and giving us a customised solution,” says Craig.
TECO MAXe3 Mining Motor Key Features:
• High efficiency motors
• True IP66 with porous drain plugs
• Class H insulation system
• Superior inverter- rated insulation (8500V/microsecond)
• Precision and rugged cast iron construction including fan
• Typical temperature rise less than Class E
• Suitable for 60˚C ambient at rated output
• Two sets of thermistors for frames D160 and larger
Bonfiglioli HD Series Key Features:
• Spheroidal cast iron housing
• I/O shaft planetary and gearbox symmetry
• Wide range of options and accessories
• High design standards
• Atex-gearbox for explosive environments 2G/2D
Ask Miner Maddie:
Electric motors need to be equipped with forced cooling fans in slow-running applications.