Engineering & Mining Journal

MAR 2013

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

Issue link: https://emj.epubxp.com/i/115330

Contents of this Issue

Navigation

Page 11 of 91

REGIONAL NEWS - U.S. & CANADA used to make significant design changes to the project, including: • Isolating and lining a portion of the proposed tailings management facility to contain tailings from the precious metals carbon leach circuit; • Shifting from open-pit to underground panel cave mining in the later years for the Mitchell deposit and also block caving the Iron Cap deposit. Underground mining is expected to reduce waste rock storage by more than 2 billion mt; • Implementing a state-of-the-art water treatment strategy to maximize environmental protection; and, • Removing planned surface infrastructure associated with the Mitchell Treaty Tunnel and placing it underground to minimize surface disturbance and facilitate wildlife access. "In our view, the consultation process has helped improve the design of the project, including some innovative, industryleading responses to evolving standards in such areas as water quality," Fronk said. Exploration drilling is ongoing at the KSM project, and the new, high-grade Camp zone discovered during the summer of 2012 has potential to add to the project's economics. Seabridge has budgeted $15 million for its 2013 KSM exploration program, which is designed to enhance its understanding of the Camp zone while also pursuing several highly prospective coppergold core zone targets. Feasibility Study Advances Sisson Tungsten-Moly Project Northcliff Resources has received a positive feasibility study from Samuel Engineering for its 100%-owned Sisson tungsten-molybdenum project in west-central New Brunswick. The study confirms the technical and economic feasibility of an open-pit project producing an average of 557,000 metric ton units (mtu/y) of WO3 contained in ammonium paratungstate (APT) and 4.1 million lb/y of molybdenum contained in concentrates over a 27-year mine life. Average annual production in the first five years of operation is forecast at 689,000 mtu of WO3 and 4.4 million lb of molybdenum. The Sisson project is located 100 km by road northwest of Fredericton, New Brunswick. The property hosts a 334-million-mt proven and probable mineral reserve containing 22.2 million mtu of WO3 and 154.8 million lb of molybdenum at a C$8.83/mt net smelter return cutoff. The average life-of-mine head grade is estimated at 0.073% WO3 and 220 ppm molybdenum. Average life-of-mine recoveries are estimated at 77% for tungsten and 82% for molybdenum. Initial capital expenditure to develop the Sisson project is estimated at C$579 million. Construction is expected to take 24 months to complete. Infrastructure and facilities at the Sisson mine site will include an open pit, crushing, conveying, ore stockpile, ore concentrator, APT plant, tailings storage facility, and ancillary buildings including offices, shops, and warehouses. Conventional mining equipment will be used, including 16.5-m3 electric-hydraulic shovels, 136-mt-capacity haul trucks, and 165-mm-dia hydraulic drills. The mine will deliver 10.5 million mt/y of mill feed to the primary crusher located adjacent to the pit. Mill feed will then be conveyed approximately 1 km to the concentrator. Lower-grade and non-mineralized material will be stored within a tailings storage facility. The average mining strip ratio will be 1:1. Mill throughput will average 30,000 mt/d. Mineral processing will consist of crushing and grinding to liberate the molybdenum and tungsten minerals, followed by flotation to recover the minerals into their respective concentrates. The crushing circuit will include a primary gyratory crusher, secondary cone crushing, and tertiary high-pressure grinding rolls, followed by single-stage, two-line ball mill grinding. Ground ore will feed the molybdenum and tungsten flotation circuits. The molybdenum concentrate will be sold to other parties for further processing, while the tungsten concentrate will be further processed on site into APT. The APT plant will be the first of its kind in Canada. Detour Gold Pours First Gold Bars at Detour Lake Detour Gold poured the first four gold bars totaling approximately 2,000 oz of gold at its new Detour Lake open-pit mine in northeastern Ontario on February 18, 2013. When the mine reaches design production rates this year, it will be Canada's largest gold mine (E&MJ;, December 2012, p. 4). Detour Gold began commissioning the first mill production line at Detour Lake in October 2012 and began processing low-grade material and then ore-grade material in January 2013. After nearly one month of operation, and despite some teething issues, the fundamental parts of the circuits were operating well. The gold inventory in the CIP and electrowinning circuits was increasing, and, in parallel, electrical and instrumentation work on the second production line was progressing well, with start-up of that line expected in March. Mining rates have continued to increase and were scheduled to reach 150,000 mt/d during the first quarter of 2013. Currently, the company has a mining fleet of 20 haul trucks and four shovels, which more than meets the requirements of the 2013 mining operation. Detour Gold's production guidance for Detour Lake for 2013 remains unchanged at between 350,000 and 400,000 oz of gold at total cash costs of between $800 and $900/oz. Life-of-mine gold production after full commissioning is scheduled to average 657,000 oz/y over a period of 21.5 years. 10 E&MJ; • MARCH 2013 Gerald Panneton (left), president and CEO of Detour Gold, celebrates the first gold pour at the company's Detour Lake open-pit mine in Ontario. www.e-mj.com

Articles in this issue

Links on this page

Archives of this issue

view archives of Engineering & Mining Journal - MAR 2013