Tailings and Mine Waste Conference

The Quillayes sand tailings dam in Chile design and operation Campaña, Jose; Valenzuela, Luis; Figueroa, A.; Alarcon, J. C.


The Quillayes sand tailings dam of Los Pelambres mine, a company owned by Antofagasta Minerals, is currently the highest sand tailings dam in Chile. The dam reached its final height of 198m in 2008 after 10 years of construction and operation. Early production at the Quillayes deposit was 114,000 tons of copper ore per day, and increased until finally reaching a production level of 140,000 tons in 2008. Existing topographical conditions provided a relatively low reservoir – dam ratio of 3:1. Therefore, a 70m-high starter embankment dam was needed, as well as high yearly increases in height of the dam during the first years. Most of the time, this required the total production of tailings be cycloned in order to produce the required dam raise sand volumes. During the design stage - originally envisaged for a maximum dam height of 175m - it was possible to test samples of sands obtained from the El Chinche tailings dam that was previously operated at the mine and designed for a much lower mine production level. This allowed for an extensive material testing program on the tailings sands, which included triaxial tests under high confining stresses, considering different densities and fines contents. The success of the Quillayes tailings dam formed the basis for the design and operation of the present tailings dam at the El Mauro mine, which has a tailings sand dam that will have a final height of 237m. This paper presents design considerations for the Quillayes tailings deposit, the water diversion scheme, and the sand tailings dam. Main construction and operational aspects as well as post-operational issues applicable to the deposit and tailings dam are also discussed.

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