Cerro Vanguardia Open Pit Mining: Database Management for Stability Analyses

Iñaki García Mendive, Gonzalo Rellán, Uriel Sterin, Alejo O. Sfriso
Sunday, November 15, 2015
First presented: 

Cerro Vanguardia is an Au-Ag mine located in the central plains of Santa Cruz, Argentina. The deposit consists of several veins 3.5-10m wide and 19km long, related to epithermal mineralization of the Chon-Aike formation by Jurassic volcanism episodes. The exploitation is carried out by means of several open pits in the range 100-240m deep. It is to be expected that more than fifty pits will be developed during the lifetime of the project.

The nature of the mineralization process caused different degrees of argillic alteration in the surroundings of the veins, especially in the form of poor quality rock bands that could potentially compromise the stability of the pit walls. Two geotechnical rock-mass characterization programmes were carried out in 2012 and again in 2015 and were employed to perform numerical analyses for slope stability assessments.

This work compares and contrasts the two analysis methodologies implemented for the two studies, with the purpose of showing a data management procedure aimed at reducing uncertainty by several geotechnical procedures. Geostatistical distribution and density of data conditioned the definition of limits between geotechnical units and the accuracy of the boundaries between them. Wide variations both in quality and amount of data implied that key parameters had to be estimated by wholly different methods. Ultimately, enhanced characterization of geotechnical units and the study of detailed analysis sections led to targeted recommendations on excavation procedures and eventually produced a more consistent and reliable pit design.

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