Engineering & Mining Journal

SEP 2017

Engineering and Mining Journal - Whether the market is copper, gold, nickel, iron ore, lead/zinc, PGM, diamonds or other commodities, E&MJ takes the lead in projecting trends, following development and reporting on the most efficient operating pr

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TAILINGS MANAGEMENT 52 E&MJ • SEPTEMBER 2017 www.e-mj.com The reality that every refining process fac- es is that for every product stream, there is a waste stream. Sometimes the reject can be recycled, but with large-scale bulk material handling applications, such as mineral processing, it's simply not prac- tical. With mining operations pursuing lower grade deposits, the industry needs a safe and cost-effective solution for tail- ings storage facilities (TSFs) capable of accommodating a 150,000 metric tons per day (mt/d). While TSFs have become a limiting factor for some operations, safety and environmental sustainability are also major engineering considerations. On av- erage, over the last 30 years, TSFs have experienced 20 dam failures per decade and a third of them have been serious safety and environmental liabilities. Two regions in the Americas are still recover- ing from the most recent serious disas- ters: Mount Polley in British Columbia and Samarco in Brazil. Many engineers believe the solution involves dry-stacked tailings (DST). The sticking point, however, is the term "dry." Traditionally, tailings are transported as a slurry. Any effort to reduce that moisture adds a cost and reduces the effective- ness of the transporting process. On top of that, many mines are operating in arid locations where water is a valuable com- modity in its own right. A little more than three years ago, FLSmidth began looking at ways to im- prove the dewatering process. The initial fruit of those efforts was the Colossal au- tomatic filter press. It uses high pressure and fast filtering to achieve much larg- er single machine capacity and optimal cake moisture concentration. It is capa- ble of discharging 20,000 mt/d of filter cake and can recover 600 cubic meters per hour (m 3 /h) of process water in a rel- atively small footprint. A large mine with 150,000 mt/d of tailings would require seven to 10 Colossal filters depending on filtration characteristics. While recovering process water on a massive scale is possible with a signifi- cant investment, FLSmidth and Goldcorp began to look for a solution that would provide a step-change for DST. They knew that allowing an increase in the moisture level of the filter cake would reduce the scale and cost of the dewatering solution. EcoTails: A New Approach to Large Scale Tailings Disposal Co-mingling coarse material with wetter filtered tails could enable the cost-effective construction of safer TSFs By Steve Fiscor, Publisher & Editor-in-Chief The EcoTails concept filters tailings fast with less machines and adds strength by co-mingling it with waste rock.

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