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Mine tailing storage represents an important environmental issue. The generation and dispersal of dust from mine tailings can contaminate air and surrounding soils. In addition, metals and soluble salts present in these wastes could pollute groundwater and surface water. The recovery of metals from mine tailings can contribute to minimize the environmental risk and to achieve a circular economy model. The main objective of the present work is to study the use of two carbon-based materials, a commercial activated carbon (AC) and a commercial charcoal (VC) in the leaching of zinc and copper from low-grade tailing waste. Experimental results obtained show that it is possible to achieve the recovery of more than 87 wt% of Zn after 6 h of leaching with different sulfuric acid solutions. The addition of carbon-based materials increases the extraction of Zn at high sulfuric acid concentrations (1 M) from 89% to 99%. The addition of VC significantly increases the extraction of Cu in leaching solution with high sulfuric acid concentration (1 M), from 41 to 61%. Future research will be necessary to optimize the properties of carbon-based materials and their recovery after leaching experiments in order to assess their potential for industrial application.

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Mine waste constitutes one of the biggest environmental and management problems, both due to its quantity and its danger when they are rich in toxic elements. There is a wide variety of waste from the oxidation of ores in metal mining areas, both metal sulphide and other minerals. These residues may be enriched in potentially toxic elements that can spread and contaminate ecosystems, farmland and villages. This study has focused on the characterization and evaluation of residues derived from metal-bearing mining waste in abandoned mining areas. Mineralogy and geochemical characteristics were determined by XRD, WDXRF and TG-MS techniques. In addition, DIN 38414-S4 leaching tests were carried out to assess the risk and mobility of potentially toxic elements. Silicates and oxides were found as the main mineral groups, followed by sulphates. These tailings were particularly enriched in Zn, Pb, As, Sb and Cd, while their leachates had high or extreme metal content. Consequently, these mining wastes are considered toxic and hazardous, even for landfills. Sulphides, as the primary source, and sulphates from their oxidation, were the main sources of these pollutants. Sulphates, As, Zn, Cd and Cu determined the specific environmental impact of the different tailing types, which were grouped into different clusters according to their mineralogy and geochemistry. These results provided a better understanding of the environmental hazards associated with the different types of metal mining waste in the area studied.

The aim of this work is to investigate the causes of the El Descargador tailings dam failure, at the mine district Cartagena–La Unión (SE Spain), in October 1963. Dam stability back analyses have been carried out by applying a geotechnical and geophysical approach. The failure occurred in the form of several landslides in five different points along the dam structure. The rise in the pore pressure and the steeped slopes of the tails, scaling up to 40° in some sectors, were the main causal preparatory factors. Here we propose that static liquefaction is the most plausible cause of the tailings dam flow failure. The presence of sand dikes and sand volcanoes with atypical stratigraphic architecture, both in the lagoon and at the surfaces exposed in the landslide areas, as well as the evidence of conspicuous sand fraction on the surface support the occurrence of the liquefaction processes. Major landslides were located near the drainage pipe and the flow directions were controlled by its position. Our results reveal that the liquefaction processes were triggered and aggravated by the poor drainage capability of the tailings dam structure.