The first expansion stage of the handling equipment of the leach pad system at the BHP-owned Minera Spence copper mine in northern Chile was completed in 2006. This impressive turnkey facility consisting of 21 highly efficient machines (bucket wheel reclaimers, tripper cars, belt wagons, stackers, conveyors) and weighing approximately 7,500 t was installed by FAM within only 24 months after the contract award. It was an extremely short timespan for such a massive, newly developed handling system.
Over time, FAM completed several further scheduled plant expansions, which included, inter alia, implementation of a second bucket wheel reclaimer and installation of additional belt conveyors. “The installed technology and the achieved performance parameters have proven the efficiency of the handling solution for the leaching processes presented by FAM, and the entire FAM plant concept enjoys now a worldwide acknowledgement and application.”
This year the mine is replacing one of the mobile conveyor bridges delivered years ago by a new bridge designed by FAM, which includes the most modern mechanical components, as well as advanced electrical and I&C technology. This upgrade will substantially increase the handling capacities in the area of leach stockpiles for copper sulphide.
By means of a tripper car, the material is transferred from the feed belt conveyor to the mobile conveyor bridge which has a center distance of 426 m. The conveyor bridge moves on a total of nine double crawlers in the direction of the stockpile. On top of the bridge, a tripper car runs and discharges the material systematically line by line using a cross conveyor. This ensures uninterrupted operation with a capacity of 5.500 tph, which results in achievement of a very precise stockpile shape using the FAM-developed control system based on GPS data.
The requirements for the ground surface preparation are low due to a special design of the crawler-mounted conveyor bridges. Owing to the new operating principle developed and patented by FAM, individual double crawler tracks can easily compensate not only for differences in ground inclination in all directions, but also in height. The position of the entire mobile conveyor can be adjusted at any time, even in longitudinal direction. The system is insensitive to temperature influences. Furthermore, the stable conveyor belt operation is ensured at all times.
The entire system has been designed for easy maintenance. A high level of component unification has been achieved, which allows to minimise the number of spare parts required for individual items, drive units and even complete undercarriages. The FAM scope of supply includes project designing, manufacturing, delivery, assembly supervision and commissioning of all mechanical components, electrical systems and control technology.
Elsewhere at the mine, FAM recently completed extensive reconstruction activities aimed at increasing the performance of the MH014 rail-bound tripper car with a slewing boom in the Ripios Section of Minera Spence, ripios being spent, previously leached ore some of which is being reprocessed.
Installation of a new, reinforced discharge boom (including a portal for the lower ring beam), replacement of the ball bearing slewing ring and installation of additional travel drives served to increase the output of the machine from 4,000 to 5,300 t/h of leached copper ore. At the same time, a new cable drum carriage was added to the conveyor line. This enables continuous operation over the entire length (approximately 1.2 km) of the shiftable conveyor CV027 without having to change the feed source for the stacking devices. FAM commented that “the quality of the work, adherence to deadlines and high safety standards during the project implementation were highly acknowledged by the customer.”
