Sierra Gorda lies in the Atacama Desert 1,700 m above sea level. And is reputed to be the seventh largest known copper and moly development on the planet. Sierra Gorda is a joint venture between KGHM International, Sumitomo Metal Mining and Sumitomo Corp. Concentrate was first produced in July 2014. Last December the mine produced approximately 700 t/d of concentrate. According to KGHM, annual production will ramp up to 120,000 t of copper, 50 Mlb of molybdenum and 60,000 oz of gold, Geometrica reports.
Sustainable mining practice with regard for surrounding eco-systems is a foremost concern at Sierra Gorda’s operation. Herbert Wirth, President and CEO of KGHM, noted the company’s uncompromising respect for people and constant dialogue with local communities, along with modern methods and management systems to responsibly extract and process copper ore and other resources.
The copper and molybdenum ore and concentrates require special storage solutions. It was imperative that the storage buildings safeguard nearby habitat from air, particulate and water pollution — a principle mandated by all the parties involved. Based on its robust portfolio of applications throughout the Andes, Geometrica was hired to provide ore and concentrate storage for the Sierra Gorda project. Two circular domes were designed to store the stockpiles while protecting the surrounding flora and fauna, including indigenous foxes, birds, lizards and geckos.
One application spans a remarkable 122 m over the copper ore stockpile — an immense structure longer than a football field. A second dome, for concentrate, spans 62 m and was welded to embedded plates on a retaining wall. It features internal cladding to protect the galvanised steel structure from any possible corrosive attack by potentially humid copper concentrate stored within the building.
With Freedome® technology, today’s domes can be constructed in a variety of dimensions spanning up to 300 m on virtually any topography. Freedomes provide an effective and efficient cover for crushed mineral stockpiles in Sierra Gorda and other mines the world over – see the bulk handling article in the April issue of the magazine.
The Sierra Gorda domes were erected by SALFA, a Chilean company with 16 years of experience that had previously participated in several Geometrica dome installations, aided by Geometrica consultants. Local labour was used to build both domes within 5 months.
Very little equipment was needed during the installation of the domes. A couple of manlifts were used to lift crew members, tools and structural elements during installation, and a crane was required while closing the apex of the stockpile dome. The resulting maximum capacity of space was achieved due to the absence of internal barriers. This allows for the free flow of traffic, personnel, equipment and inventories.
Intermediate columns were simply not required. The dome’s geometry was weaved around a complex conveyor support structure. Yet the resulting structure is very strong… strong enough for the most challenging climates, brutal wind velocity, and seismic loads of the Sierra Gorda region.
The cladding on both Sierra Gorda domes was designed with compatible profiles and installed over the course of six weeks without the need for special framing or equipment. Translucent panels contribute natural lighting, energy cost savings and customized symmetrical patterns for additional aesthetic beauty. The result is a continuous surface that provides effective sealing and water drainage.
