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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Page 57 of 99

TAILINGS MANAGEMENT 56 E&MJ • SEPTEMBER 2017 Satisfaction Guaranteed. Providing unmatched engineering excellence, low lead times through global inventory stock, attentive customer service, and cost-effectiveness for our customers. Call Us for more info 9410 Florida Mining Boulevard East Jacksonville, Florida, 32257 (904)356-6840 Drop-In Replacement Parts. High quality parts designed for drop-in replacement of Warman® pump parts, engineered to handle the requirement of your operation, backed by OEM equivalent warranties. Any reference to trademarks owned by Weir Group PLC, e.g. Warman®, are for reference purposes only, and do not imply authorization or affi liation of Schurco Slurry® with Weir Group. decanting process needs to be removed. On average, the mining industry experi- ences two TSF dam failures per year. It's not the dam failure that causes the dam- age, however, it's all the water behind the dam that fouls downstream waterways or worse. A dry-stacked TSF can still fail, it will only flow 100 m instead of 100 km. Additional storm water will not accumu- late because of the low permeability; the water simply runs over the top. The lower permeability could also have a long-term positive impact regarding ARD potential. "This won't eliminate all ARD, but there are studies that say that if the saturation level of a pile is 85% or more, you can stop ARD, but we haven't proven that yet," Wisdom said. Thickeners recover around 70% of the process water. The filter presses re- cover much of the rest. "EcoTails doesn't remove any more water than traditional filtered tailings, but it can be applied to more mines economically," Wisdom said. The filter cake does contain some water and the mine will need some type of col- lection point for storm water runoff, but there will not be much seepage because of the permeability of the pile is so low. Justifying Costs For a traditional TSF using a rock filled dam, in general operating expenses are estimated at $1.50/mt and the capital expenses are $1/mt. Typically, the water ratios are between 0.5 and 0.7. "What we have determined, and we are in the process of performing the pilot scale testing and plant demonstrations to prove this … with the generic EcoTails case, we see operating expenses at $2/ mt and capital expenses $0.50/ton or lower," Wisdom said. "That puts this solution on an even keel with traditional systems over the life of a mine. "Moreover, if the mining company is considering a 1-billion-ton reserve, they will be looking at $500 million in capital cost and $2 billion in operating expens- es," Wisdom said. "While those numbers are a bit staggering, we are going to prove that EcoTails is directly competitive on a total cost basis with conventional wet tail- ings. They cost the same, but GeoWaste presents less risk and recovers more wa- ter and that should be a winner in the marketplace." Again, the water savings are not any greater than traditional filtered tails, it will just make the process more appli- cable. The old rule of thumb for filtered tailings, Wisdom explained, was an all-in placed cost of $4/mt. "We are trying to cut that significantly," Wisdom said. Water costs are relative. In South America, water costs are estimated be- tween $5/m 3 and $7/m 3 . "If a 100,000- mt/d operation changes its water ratio from 0.7 to 0.17, which is what should happen when they switch from a tradi- tional cyclone sand dam to a filtered tail- ings solution, the amount of makeup wa- ter that they would need decreases from 70,000 m 3 /day in the sand dam case to 17,000 m 3 /day," Wisdom said. "That's 53,000 m 3 /day in water savings. Over 10 years, that's about 200 million m 3 and, at $5/m 3 , that's $1 billion in water savings. "That's a big number and when you combine that with being cost competitive and safer, it seems like a solution that will have some traction for the industry," Wis- dom said. More times than not, mining gets a bad rap due to these environmen- tal mishaps. EcoTails could present an environmentally sustainable solution to increase productivity that's economically and socially acceptable.

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