Abstract

The aim of this work was to establish the intervention requirements of 30 tailings deposits located in the region of Antofagasta, Chile, identified in the National Tailings Survey carried out by the National Service of Geology and Mining of the Chilean government in 2017. For the evaluation, the data of 49 geochemical characterizations of the samples registered as of October 2017 were considered. The methodology used for evaluation was based on the Dutch Soil Regulation Circular, from which two ways of assessment were developed. The first approach uses a simple graphic method that depends only on the concentration of the elements in the solid phase of tailings and the percentage of clay in the soil. The second approach considers that the information related to the clay percentage is not available, therefore, this work defines the concepts of threshold factor and adjusted threshold factor. Using the proposed method, this work presents the analysis carried out on the elements of environmental significance related to mining activity in Chile: Cu, Cr, Ni, Zn, Pb, As, Cd and Hg. The methodology allows delimiting areas of foreseeable risks for people and/or environment, resulting in three criteria for each element: 1) requires intervention, 2) requires conditional intervention, 3) does not require intervention. These results are summarized by means of a final score that determines the level of priority assigned to each sample. The analysis of results indicates that Hg intervention is not required, there being only one case requiring conditional intervention. Regarding Cu and Zn, 100 % of the measurements indicated at least the requirement of a conditional intervention. Within the region, the commune of Sierra Gorda contains 67 % of the tailings whose intervention must be prioritized according to the score obtained (greater than four out of a possible maximum of eight). On the other hand, the two tailings of greater tonnage (the sites of Talabre and Laguna Seca) do not present a requirement for priority intervention at the moment.