The Sangdong Tungsten Molybdenum Project is located 187km from Seoul, South Korea. The mine is 100% owned and operated by Woulfe Mining (formerly, Oriental Minerals). Spread over an area of 3,173ha, it is considered to be the largest tungsten resource in the world.
Sangdong was one of the leading tungsten producers for nearly 40 years, before ceasing production in 1992 due to low metal prices. Woulfe acquired the mine in 2006 and has been carrying out drilling activities to establish its economic feasibility.
The South Korean government approved the development of the mine in June 2010. A feasibility study for the mine was completed in April 2012.
Woulfe is investing $140m in the underground project and will initially focus on the upper levels of the mine. First blasting for the underground mining was done in October 2012. The mine is expected to produce 1.2 million tons (mt) per annum. Production is expected to commence in mid-2013.
Sangdong geology and reserves
Sangdong is a skarn-type deposit containing altered horizons of the Cambrian-age Myobong Shale formation. The metamorphosed strata include a le biotite granite unit located at a depth of 700m. The lower most zone is the Jangsan quartzite unit, above which lies the Myobong shale unit. The Great Limestone unit completes the series of altered horizons.
Inferred resources based on a cut-off grade of 0.10% tungsten trioxide (WO3) are estimated at 45.8mt grading at 0.35% of WO3 and 0.04% of molybdenum disulfide (MoS2).
Mineralisation of tungsten molydenum project
Tungsten mineralisation is carbonate-hosted and formed due to the alteration of limestone by mineralising fluids. The main tungsten mineral is scheelite, which contains over 95% of tungsten. Minor quantities of wolframite are also found.
The altered horizon is divided into several zones including Main, Hangingwall and Footwall. The Main zone hosts the highest grade mineralisation. It extends 1,300m and is 5m to 6m thick. The zone has been extensively mined compared to the remaining ones.
The Hangingwall zone extends to a depth of over 600m and is 5m to 30m thick. The Footwall zone, below the Main zone, contains number of 2m thick layers.
Mining and processing ore
Ore located near the Footwall and Main Zones will be mined initially using drift and fill mining method. These zones will be accessed through a 6m x 6m adit and decline. Jumbos, shovels and haulage trucks will be used to extract the ore.
Recovered ore will be processed by a crushing circuit, milling facility, floatation plant and a state-of-the-art tungsten processing facility.
Run of mine ore will be stockpiled on surface until the completion of the floatation plant, crushing plant and processing facility. More than 10,000t of ore was produced during exploration and trial mining. It has been stockpiled on surface.
Facilities at the mine will include a warehouse complex, office buildings, an accommodation complex and utilities. A purpose-built transmission line will supply power to the mine from the electrical grid.
The recovered ore will be sent to a crushing circuit comprising of a jaw crusher, screens and a cone crusher. It will be crushed to a size of 10mm and then sent to the milling unit where it will undergo two-stage milling. The ore will be classified and sent to a three-stage floatation plant to produce molybdenum, bulk sulphide and tungsten concentrates.
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The tungsten concentrate will be sent to a tungsten processing facility to be refined and converted into high-quality ammonium paratungstate. The processing plant is expected to produce 5,000t of tungsten trioxide and 500,000lb of molybdenum concentrate.
Tailings from the facility will be sent to a backfill plant for processing and used as paste fill underground. Excess tailings will be sent to a dry stack storage facility.
Jinheung Mining Company is carrying out the mine’s development. HanmiGlobal is the construction manager for the project.
Contromation Energy Services is providing the detailed engineering design for the processing facility.