Silvercorp acquired the TLP silver-lead mine in December 2007. Located directly east of the Ying mine (240 km southwest of Zhenzhou, the capital city of Henan Province in central China), the TLP mine operates under a mining permit covering an area of 3.3 km2 from surface at 1,140 m elevation to a depth of 700 m with an overlapping exploration permit that covers the area below 700 m elevation. Commercial production commenced March 2008.
The TLP Project is 100% owned by Henan Found Mining Ltd., a sino-foreign cooperative JV company owned 77.5% by Silvercorp (through a wholly owned Chinese subsidiary) and 22.5% by the Henan Non-Ferrous Geological & Mineral Resources Co. Ltd. The cost to acquire the mine was approximately US$22-million.
Silver-lead veins in the TLP area were exploited for several centuries by artisanal miners but the area was not systematically explored or developed until the Chinese government initiated activities in 1956. Since then, the area has been mapped, sampled and surveyed in considerable detail. Intense surface and underground exploration from 1985 to 1995 defined significant historical silver and lead resources and serious organized mining began in 1998. Mining operations in the area were closed in 2006 for safety and environmental reasons before being acquired by Silvercorp in December 2007.
The TLP mine area has 36 known mineralized veins. Many of these were discovered only recently in the 2010 exploration campaign. The veins are generally similar to those found throughout the Ying mining district, occurring as sets or systems of veins of similar orientation which are enclosed by steeply-dipping fault-fissure zones that extend for hundreds to a few thousand meters along strike. The veins are narrow, tabular or splayed, with rich mineralization often occurring in pockets or ore shoots too often having vertical and horizontal extents of several tens of meters or more. The mineralization consists mainly of galena (lead sulfide) with lesser amounts of sphalerite (zinc sulfide), chalcopyrite (copper sulfide) and sparse amounts of other metallic minerals. The metallic minerals occur as disseminations or massive accumulations in a gangue of quartz and carbonate minerals. Silver is present mostly as microscopic inclusions in the galena.
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The TLP mine lies about 11 km east – southeast of SGX. There are 36 known veins, all dipping westward. The mine is serviced from 10 adits and the mining plan currently shows production occurring through to 2023 from stopes between the 200 and 1100 levels and from vein widths generally between 0.3 m and 3.3 m. Over 95% of stoping is envisaged as being by shrinkage, the remainder by resuing. About 16% of Ying 2011 production tonnes (6% of Ag ounces) came from TLP. TLP utilizes several mine development systems: including adit, blind decline and blind shaft. Since several ore veins occur very closely, the development system on each level is shared. The adit development system is used to access veins at the 730m level and above. A combined adit, blind decline and blind shaft development is used to access ore veins between the 730m and the 510m levels. All mining and development activities are completed by a mining contractor. Concentrates are sold to smelters within Henan province, many located within 160 km of the mill. Payable prices are based on the 10-day average spot price on the Shanghai Metals Exchange less Value Added Tax and smelter charges.
Exploration and delineation of mineralized veins in the TLP vein system is done primarily from underground workings - tunnels, drifts, crosscuts and declines, typically about 2 x 2 m in size - and by extensive underground long-hole core drilling. Tunneling, typically at levels 20 to 50 m apart in elevation, is done along strike of the veins to define character and tenor of mineralization in the veins. Long core holes are drilled from the underground workings at 50-100 m spacings along strike to delimit extent of the veins at depth.
Last updated October 11, 2013