The third thickening facility of the Sierra Gorda Mining operation in Northern Chile was commissioned in Summer 2023. PENETRON ADMIX, a crystalline waterproofing admixture, was used to protect the SCM facility’s concrete structures from the toxic copper tailings.
The Sierra Gorda Sociedad Contractual Minera (SCM) mine is located about 60 km from the city of Calama in Northern Chile (Antofagasta region). The mine operation, one of the largest in the world, produces copper, gold, and molybdenum and has proven ore reserves of 800 M tons.
SCM expects to reach daily processing levels of 140,000 tons of copper ore. This also results in a corresponding increase in tailings, the toxic mining waste that remains after separating the copper ore. Tailings are usually stored as a liquid or a slurry of fine particles.
“Traditionally, waste disposal has been an environmental challenge for mining operations. But now, the industry has begun to embrace a process of thickening these tailings to better address the challenge,” explains Domingo Lema, Managing Director of Penetron Chile. “At SCM, the ongoing ramp-up of copper ore processing made it necessary to expand the treatment capacity of tailings by building a third thickener facility.”
Thickening copper tailings is essentially a dewatering process, utilizing gravity-driven collection systems which separate the tailings into a dense slurry containing most of the solids and an overflow that draws off essentially clear water.
"A thickener facility produces two products: clear water at the top, which is recycled, and a thickened slurry at the bottom," summarizes Domingo Lema.
During the planning stage of the SCM project, Eugenio Rojas, an engineer with Golder Engineering, the project’s designer and engineering consultant, reached out to Penetron Chile to learn more about the performance of PENETRON ADMIX, a crystalline waterproofing admixture for concrete, which had been successfully used in previous projects at the Sierra Gorda mines.
“Once we were able to show Señor Rojas how our admixture would provide the necessary concrete durability, PENETRON ADMIX was added to the technical specifications for the thickener facility,” adds Domingo Lema.
Construction of the new thickener facility was carried out by Puga, Mujica y Asociados. Sociedad Petreos, the ready-mix concrete supplier, provided 2,800 m3 of PENETRON ADMIX-treated concrete for the treatment tanks, pump shaft structure, and the tunnel slabs of the facility.
Once PENETRON ADMIX is added to the concrete mix, the proprietary chemicals in the admixture react in a catalytic reaction with moisture to generate a non-soluble crystalline formation throughout the pores and capillary tracts of the concrete. This formation permanently seals micro-cracks, pores, and capillaries against penetration of any of the liquid toxic waste present in the tailings pumped into the thickening facility. The non-soluble crystalline formation generated by PENETRON ADMIX becomes an integral and permanent part of the concrete matrix.
“PENETRON ADMIX was chosen for this new SCM thickening facility thanks to lower costs and a reliable guarantee of permeability reduction and continuous self-healing of cracks throughout the service life of the concrete structures,” concludes Domingo Lema.
Penetron provides key concrete durability: One of the largest in the world, the Sierra Gorda Sociedad Contractual Mine in Northern Chile (Antofagasta) produces copper, gold and molybdenum.
Protected from toxic waste: PENETRON ADMIX-treated concrete was specified for the Sierra Gorda Mine’s treatment tanks, pump shaft structure, and the tunnel slabs of the facility.
