?As is well known, the availability of water for mining processes in Chile is limited. In addition, it should be considered that the vast majority of mining plants are located in the northern part of the country, which is for the most part desert, and mainly at a high altitude. Given the low availability of water, various alternatives have emerged such as thickening tailings to high concentrations by weight (recovering more water in the thickeners) or using desalinated seawater. The present study aims to define the optimum thickening concentration for copper tailings, applied to a case study of representative Chilean mine tailings, from a rheological and energy point of view, as a function of recovered water in the thickeners and specific energy consumption (SEC), transporting one ton of Non-Newtonian thickened tailings. The specific energy consumption (SEC) should be related mostly to the solids transported than to the mixture, with thickening becoming a relevant parameter, since in slurry transport, the solids are usually the "payload", while the conveying fluid is simply the "vehicle". The result of this paper provides the industry with an additional variable to consider in the optimum grade of tailings thickening and rheological design parameters for projects, which could be considered in conceptual and pre-feasibility stages or in the optimization of existing systems.
This paper presents a case study on the design of a thickened tailings storage facility (TSF) for a proposed open pit copper mine at Dareh Alou, Iran. Dareh Alou mine is a new copper mine owned by National Iranian Copper Company (NICICO). It is located in the Kerman Province of the Islamic Republic of Iran. The nominal production rate is 7 Mtpa for a life-of-mine (LOM) of 25 years. Planning was undertaken for the accommodation of a total of 175 Mt of tailings. The Dareh Alou mine site is located on a sloping side of a valley that is surrounded by hills, grading up to steep mountainous terrain. Since this is a greenfield project the location of the concentrator was selected in conjunction with the tailings deposition options study. Five concentrator locations with various ore transportation options have been investigated together with the tailings and water management study. The result of the study indicated that the best concentrator plant location was at RL 3050 m at approximately 2.5 km from the preferred TSF location. Various tailings and water management options were evaluated, including high rate, high density/high compression, and paste thickeners. These dewatering options were studied alongside the combinations of various TSF and thickener locations. The outcome of the options study indicates that if the price of make-up water is not included in the analyses, the preferred option is utilisation of high rate thickeners. However, after inclusion of make-up water at a rate of USD 1/m3, the preferred option would be the utilisation of high density/high compression thickeners. In this case, the distance between the concentrator and the TSF is such that transportation of un-thickened tailings to thickeners located adjacent to the TSF is the most efficient option. Also, thickening the tailings will provide benefits in reducing the embankment construction cost even though relatively large embankments will be required to close off the valley site.
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).
?Inspired by the success of cemented paste backfill in the west orebody of Chambishi Copper Mine, integrated disposal of paste backfill and surface high-concentration tailings stacking was applied in the southeast orebody. This paper presents the integrated disposal system, including two deep cone thickeners, double-shaft horizontal mixer, two plunger pumps for underground backfill and three diaphragm pumps for surface stacking. The challenges of the integrated disposal system were deep backfilling (0.98 km) and long-distance discharging (15 km), so a combination of gravity flow and pumping was used in paste backfill and three diaphragm pumps with a preset pressure of 7 MPa were applied for surface stacking. The annual ore production in the southeast orebody is 3.3 Mt, which is 3.3 times larger than that of the west orebody. Therefore, the capacity of the integrated disposal system also needs to be expanded. The capacity of the paste backfill system and surface stacking system were 160 m3/h with paste concentration of 75 wt.% and 265 m3/h with slurry concentration of 55 wt.%, respectively. In the first phase, the cement to tailings ratios for primary and second stopes are 1/8 and 1/24 respectively. To meet the backfill strength and reduce the cost, waste rock will be added in paste backfill in the second phase, the waste rock to tailings ratio is 1/3, the cement to tailings and waste rock ratio for primary stopes are 1:12, and 1:30 for secondary stopes. As a result, the UCS after 28 days for primary and second stopes were 1.2 MPa and 0.5 MPa, respectively.
?Several large copper mines are evaluating improvements in the tailings dewatering circuits. Most prevalent alternatives being considered optimize their thickening technologies or the implementation of tailings filtration and stacking. This requirement to optimize water recovery is due to a variety of factors; the deficit and high cost of the water make-up, environmental restrictions, and community relationships. The recent failures in conventional tailing deposit structures and the potential change to reduce the footprint of tailings impounds may also drive the desire to consider alternate technologies. This paper presents technical and economic review of alternate technologies, considering capital investment and operational costs. The five (5) selected alternatives include thickening technologies, pressure filters and a combination with cyclones for classification and filtration of the coarser fraction and thickening of the finer fraction. The selected alternatives are developed and evaluated at trade off study level.