ABB and Takraf reported Sept. 28 that they commissioned and tested what's reported to be the world's highest-powered, gearless conveyor drive system, enabling continuous operations at the Chuquicamata copper mine in Chile.
ABB provided engineering design, gearless conveyor drives, electrical equipment for power supply, energy distribution and automation of a new underground and overland conveyor system at one of the world's largest open-pit copper mines. Commissioning was completed in four months, and the new underground conveyor is expected to extend operations at Chuquicamata for about 40 years.
Project management and engineering for the full electrical, control and instrumentation (EC&I) scope was led by ABB in Germany and onsite with Takraf in northern Chile to equip the site’s underground operation with a large conveying system that overcomes an altitude difference of 1,200 meters and covers a distance of almost 13 kilometers. (A video of the project is at https://youtu.be/tYHsqwo4TJU)
The three principal 11,000 tons per hour (tph) conveyors feature gearless conveyor drives (GCDs) equipped with large ABB AC synchronous motors with a rated power of 5 megawatts (MW) each, resulting in a motor shaft torque of about 900 kNm. With every line in constant use, high availability and low maintenance are essential. Because the conveyor system was designed to require just one underground transfer station, it also saved on project costs.
Based on continuous conveying technology, the new infrastructure is completely truckless, eliminating the need for 120 large haul trucks. This saves about 130 million liters of gasoline per year, bringing the carbon emissions from 340,000 t p.a. down to 100,000 t p.a. It's also reportedly the world's first transportation system to employ ST10000 steel cable belt technology on uphill tunnel conveyors.
“This mega project achieves a number of firsts, from the system’s installed drive power to the application of the ST10000 conveyor belt,” says Marc Hollinger, project manager at Takraf.
“This is a new milestone in underground applications for continuous mining. It's the highest drive power ever installed on a conveyor and uses a wide range of features for data aquisition, equipment assessment and process optimization,” adds Ulf Richter, global product manager for belt conveyor systems, at ABB. “In piloting this gearless drive application with Takraf, we overcame tremendous technical and logistical challenges due to underground situations, elevation change and capacity requirements.”
ABB reports that liquid-cooled MV voltage-source frequency converters, together with large synchronous motors, deliver a decrease in active and reactive power consumption. This is highly energy efficient and doesn't need added network filters.
A novel embedding concept, developed jointly by Takraf and ABB, enables straightforward installation and alignment of the GCD motors, saving installation time and reducing deployment of maintenance teams. They report this concept was a major benefit compared to existing GCDs in cantilevered construction. The concept also meant motors were 100% factory assembled and tested. They can also be mechanically disconnected from the drive pulley quickly, so operations can continue if drive failure occurs. The total installed drive power for the entire system, including multiple feeder conveyors, totals 58 MW, of which there are 11 x 5 MW gearless synchronous motors.
Meanwhile, ABB’s Mining Conveyor Control Program (MCCP) ensures smooth belt operation and safe synchronization between high-power motors and high-power hydraulic brakes, which are necessary for secure operation of steep uphill conveyors. The drive systems also work without mechanic backstops.
