Tailings are the materials left over after the process of separating the valuable fraction of ore from the gangue. Tailings ponds are engineered structures created using dams, berms and natural features such as valleys, hillsides or depressions. The pumping of tailings slurry into a pond allows the sedimentation of solids from the water. Tailings ponds can be highly toxic because they are used to store harmful waste made from separating minerals from rocks or the slurry produced from tar sands mining. To minimise contamination of underlying groundwater, high-density polyethylene (HDPE) liners are used. These liners are prefabricated sheets that are welded onsite to form a continuous waterproofing membrane that prevents the migration of contaminated water into the environment. Despite their widespread application, HDPE liners have inherent performance limitations, such as leakages at the location of welds, UV resistance, maintenance and repair. This paper considers a new type of sprayable reactive membrane as a waterproofing structure. Permeability tests with the Rowe cell, chemical and durability tests (interaction with water and leachates at different temperatures, oxidation and UV resistance tests) and mechanical tests (tensile strength tests, elongation tests, puncture tests) were performed and compared with conventional HDPE membranes for tailing ponds. Results showed that the new sprayable membrane has good performance comparable with the conventional HDPE membrane and it can be a very attractive solution for tailings ponds liners
In the present study, laboratory experiments were performed to investigate the geotechnical properties of four different tailings, including two iron tailings (coarse and fine) and two copper tailings (coarse and fine).
?Chile produces large amounts of tailings daily which must be safely disposed on the earthÂ’s surface. There are a series of strategies that have been successfully used in our country to store tailings, among them are thickened and paste tailings. Paste tailings are an advantageous technique that allows for greater recovery of water while improving physical stability of the structure. Although challenges are faced worldwide when large production rates are tried to be thickened, the technique seems promising for countries like Chile where there is an ongoing water crisis. The stability of paste tailings facilities is highly influenced by water content or saturation. As consolidation occurs the tailings loses water. However, as the evaporation front takes place, the material goes from a saturated to a non-saturated state. Unsaturated paste has shown improved resistance, e.g. liquefaction resistance almost double when saturation drops below 90%. A well planned facility operation should consider the monitoring of the water content of the paste. However, this is sometimes difficult, due to the large areas that must be controlled and the danger associated with manual moisture measurements in the field. In this context, we proposed the use of hyperspectral cameras to obtain a relationship between the paste moisture content and light reflectance. This would allow to generate moisture surface map and to the use of this data to monitor for instance evaporation rates or water balance in tailings storage facilities. This article summarizes laboratory main findings and proposes a series of procedures to implement the technique in the field.
Thin spray-on liners (TSLs) provide areal support to rock excavation surfaces, and have been implemented in the mining sector for over 20 years. However, scepticism over their usage still prevails, despite the results of laboratory research that has been carried out indicating their effectiveness for use in mines. The study described in this paper aims to highlight TSL performance as viewed by the mining industry. Some underground cases of practical performance have been singled out and compared with the expected performance based on information from suppliers and from laboratory testing perspectives, and the causes of the resulting quality of performances were categorised. Among the causes of the discrepancies between expectations and observations is the lack of inclusion of parameters such as temperature and humidity in the laboratory tests, which could have significant effects on the liner performance since, based on results from Brazilian indirect tensile tests on coated samples, their inclusion doubles the probability of failure and therefore, increases the predicted geotechnical risk of failure. Consequently, to take into account potential performance discrepancies, some existing recommendations and further potential recommendations are suggested in the paper. If later validated, these suggestions could be included in a good practice guideline for TSL application in underground mines.