At the entrance of the Cerrillos Canyon in northern Chile lies the Coemin facility, a plant that processes raw copper ore from the Crola mine. Located 30 km southeast of the city of Copiapo, this area is also an important wine region, with dust from ore handling and crushing obviously not desirable for the vineyards. Coemin had long used preventive measures such as foam sprays and fabric barriers to control emissions. But as the plant has grown and existing measures where no longer sufficient they then decided to completely enclose their crushing operations in a customised dome solution from Geometrica.
The task was a challenge, as the equipment and conveyors were not laid out with an enclosure in mind. The main area encompassed more than 5000 m2, in a shape that was irregular after several expansions. The initial concept consisted of two smaller domes and a huge arched vault for the facility’s largest area. Local suppliers were consulted, but the spans for the big area were simply too large and complex. As a result, Coemin’s in-house architect and Head of Projects, Percy Diaz, contacted Geometrica for a proposal. The large arched vault had its drawbacks. Bending stresses were very large. It would have required increased truss depth and structural members that would have been too heavy. Clearances for access and interior space would be compromised. This vaulted shape meant that some of the existing equipment would have to be modified or have to remain uncovered. Equipment modifications were undesirable as they would require plant downtime. Geometrica proposed a very different solution, a Freedome, Geometrica’s brand name for a free-style dome. Geometrica considered the scope and scale of the new vision and confirmed that the Freedome could be built without increasing the budget.
The new challenge was to design and engineer a dome that would spring from this very irregular plan. Existing equipment and buildings dictated the shape as crushers and sifter equipment had to be enclosed, while a hopper had to remain outside. The supporting structure had to bridge existing buildings. There was no way to fit a conventional circular dome on this site. Diaz’s plan was a heart shape — roughly three sided with rounded corners and a dimple in one of the sides. Spans were 90 m in the principal directions. The Freedome was the solution and no equipment modifications were required. When the dome was approved for construction, all elements varied — meaning this project was “truly a custom architectural achievement” and was installed using local labour who had no problems following the simple procedures required to build it.
Construction of the dome started on the foundation and progressed toward the apex, ring by ring. No scaffolding, nor operating downtime were required, as the partially built dome supported its own weight plus that of the construction crews through the whole process. Cladding consisted of rectangular corrugated metal sheets with with a polyester finish. The Freedome, plus the two smaller domes, now control dust emissions from the plant’s material processing while the vineyards are protected.
