The project was carried out at Collahuasi’s mine in northern Chile, about 180 km southeast of the port of Iquique, at an altitude of 4,400 meters. This mining district has been in business since 1880 with the exportation of high-grade copper-silver vein systems. Currently, it is dedicated to the extraction and production of copper and molybdenum concentrate. During 2016, Collahuasi was the third-largest copper operation in the world and has one of the largest deposits of mineral resources of copper on the planet (9.964 million tonnes). Its shareholders are Anglo American plc (44%), Glencore (44%) and Japan Collahuasi Resources B.V. (12%).
Collahuasi was facing the great challenge, common to many of the global mining groups, of optimizing its operations to achieve the highest levels of efficiency. “In order to ensure productivity and profitability in the future, Collahuasi has decided to develop a preventive maintenance improvement program, which is comprised of a master plan to maximize availability and minimize bottlenecks, through a long-term and sustainable approach. Its objective is to detect potential problems in advance and maximize the performance and availability of existing equipment,” commented Dalibor Dragicevic, vice president for processes at Collahuasi.
In addition to the VPA filters, Collahuasi also has other equipment from Metso such as semi-autogenous (SAG) grinding mills, ball mills and and Vertimills®.
Ageing equipment poses a challenge
Thanks to the collaborative relationship between Collahuasi and Metso, a joint diagnostic meeting was held to review the main needs and potential improvement to the filtrate-concentrate level, which was related to the requirements of its VPA vertical filters to increase their production capacity while also increasing the overall reliability of the system.
Due to the high productivity requirements and over 20 years of use since its installation, the filters were showing a high degree of wear and misalignment, which reduced their availability due to the extra maintenance required by the filters and considerable unplanned downtime.
During the review stage of the overhaul, a joint decision was made to make improvements and upgrade the control systems, lubrication and structure of the equipment in order to achieve higher levels of availability.
Equipment refurbished to as new condition
The challenge for Metso resulted in upgrading the control systems to the latest technology, achieving values of over 92% availability and 100% of design capability. This involved reinstalling and upgrading equipment in less than 20 days in order to minimize lost production. The engineering coordination, parts procurement and planning activities began six months earlier in order to ensure the complete compatibility and successful outcome of this upgrade.