Chatree Gold Mine is the largest open pit mine in Central Thailand which produced 74,137 ounces of gold in July 2007 – June 2008. The Chatree deposits consist of complex andesitic centers adjacent to the rhyolitic centers. Structural geological of interested area (CH pit) can be divided in to 3 main structures: sheared zone, andesite dykes and faults. The point discussed in this paper is general production blasting practice and controlled in 6 meters bench using three main blast patterns with powder factor between 0.35 and 0.80 correlated to rock type. Trim blasting and pre-split blasting have been proposed, trialed are also include. The present practices are mentioned.

1.1 Background

The Chatree Gold Mine is located 300km north of Bangkok in Thailand. The Chatree deposit was discovered in 1995 in an area not previously recognized as having potential for significant gold mineralization. Mining leases were applied for and granted in 2000 and Chatree North Project mining leases were granted in 2008. The Chatree Gold Mine commenced production in November 2001 after a 12 month construction period.

Load and haul is done using a fleet comprising of O&K RH40E excavators, Cat 773 and 740 trucks, Cat 14M Grader and Cat D8 and D9 Dozers. Mining and haulage are done by local Thai contractor, Lotus Hall Mining. This contract was updated in 2007 to allow for a new and expanded mining fleet, supported by Caterpillar, for increased production at Chatree for the year ended 30 June 2008 was 74,137 ounces of gold and 232,039 ounces of silver.

The mine is conventional open pit operation consisting of three currently operating mine areas (A,K east and C cutback) and six closed pits (p, CH,H west, H south, D and S). the mine area spans approximately 7.5 km by 205 km and the deepest pit wall is 153 meters from surface (Plate 1).

(Plate in full paper)

The slope angle is designed correlated to rock types, which are 35The slope angle is designed correlated to rock types, which are 35° in laterite layers, 45° – 50° in transitional rock and sheared rock, and 60°- 65° in fresh rock. Catch benches of 5–6 meters are introduced every 18 meters bench height. Blasting is done every 6 meters for two excavation flitches of 3 meters.

This paper detailed the procedures and practices that have been developed for a production blasting and anear-wall blasting in Chatree Gold Mine closed and currently operating pits.

1.2 Geology

The Chatree deposits are located in the Western-Edge Khorat Plateau Gold Belt at the boundary of Phichit and Phetchabun Provinces, central Thailand. The deposits consist of complex andesitic centers interdigitate and are overlain by fine-grained volcaniclastics and epiclastic siltstones, mudstones and fossiliferous limestones. Instructions of diorite to dolerite occur in the region. There are also stocks and swarms of ddykes and faults in the area and granitic intrusions are associated with regional structural trends. While CH pit is dominantly composed of lithic rich fiamme breccias, polymitic and andesite to andesite porphyry.

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