Engineering & Mining Journal

NOV 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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REGIONAL NEWS - LATIN AMERICA 14 E&MJ • NOVEMBER 2017 www.e-mj.com Escondida's Copper Production Ramps Up Minera Escondida has finally shaken off the effects of a labor strike that impacted production at the mine for 44 days be- tween February and March. The mining company, which is owned by BHP, report- ed that copper production had increased by 23% to 268,000 tons during the third quarter of 2017. According to the company, the increase was due to the start of the operation of the Los Colorados Extension project during September, plus higher average ore grade and higher amounts of ore processed. The company has calculated that Los Colora- dos will reach peak capacity in the last quarter of 2017, thus allowing the use of three concentrators and a production that ranges around 1.2 million tons for fiscal year 2018 (July 2017-June 2018). BHP's Chilean operations increased its copper production by 14% to 404,000 tons, while its estimate for fiscal year 2018 remains between 1,655,000 tons and 1,790,000 tons. Fortuna Starts Building Lindero Gold Project Fortuna Silver Mines has started con- struction of its 100% owned Lindero gold project in Salta province, northwest Argentina. Gold recovered to doré will average 96,000 ounces per year (oz/y) over a mine life of 15 years, with peak production in the first two years of about 137,000 oz/y. All-in sustaining costs of production are estimated at $802/oz. Initial capital required to develop the Lindero project is estimated at $239 mil- lion, including $19 million for an own- er-operated mining fleet and $24 million for contingencies. Sustaining capital for the project is estimated at $105 million. The project has an approved environ- mental impact study and has been grant- ed all major permits for construction. Lindero will be an owner-operated, con- ventional open-pit mining operation, pro- ducing a nominal 18,750 metric tons per day (mt/d) of ore. Key mining equipment initially will be six 100-mt trucks and two 17-yd 3 wheel loaders. Mining costs will benefit from short haul distances from the pit to the primary crusher and waste dumps. Maximum distances are in the range of 2 km. Life-of-mine direct mining costs are estimated at $1.1/mt moved. Ore will be crushed through a three- stage crushing system with high-pressure grinding rolls in the tertiary stage. The crushed product will be agglomerated and cured with a cyanide solution and then conveyed to the leach pad. A mobile con- veying and stacking system will be used to stack ore in 10-m-high lifts. The life-of- mine leach pad area is projected at 105 ha, with a maximum height of 100 m. Leaching will be carried out in two stages, with a first stage of 30 days and a second stage of 60 days. Pregnant solution will be pumped at a rate of 400 m 3 /h to an SART (sul- phidization, acidification, recycling and thickening) plant, where copper content in solution will be precipitated to main- tain copper levels below 400 ppm in the solution. The project contemplates an expansion of the pregnant solution flow rate from 400 m 3 /h to 600 m 3 /h in year four, with the objective of reducing in- ventory of gold ounces in the heap at the end of mining. Following the SART plant, the pregnant solution will go to an ADR (adsorption, de- sorption and regeneration) plant and then to electrowinning and refining where gold will be recovered as doré bars. Life-of- mine recovery is estimated at 75%. Project commissioning is planned for the second quarter of 2019. The Lindero porphyry gold system re- mains open at depth below the current pit shell of reserves and resources, with high- grade drill intercepts bottoming in min- eralization. The nearby Arizaro porphyry system, located within the Lindero con- cession, is a near-term exploration target. Tinka Explores for Zinc in Peru The president of Canadian mining compa- ny Tinka Resources Ltd., Graham Carman, estimated that it will need about $20 mil- lion for its Ayawilca project in the next two years, the zinc-silver-lead-tin project locat- ed in the Peruvian department of Pasco. "We have a very interesting project, which is zinc, which is one of the biggest discoveries in Peru in several years," Car- man said. In 2016, after six years and 27,200 meters (m) of drilling, the company in- formed inferred mining resources for After suffering production setbacks earlier in the year, Minera Escondida's production returned to normal in the third quarter.

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