Mining
The Chatree Gold Mine is located 280km north of Bangkok in Thailand. The Chatree deposit was discovered in 1995 in an area not previously recognised as having potential for significant gold mineralisation. Mining leases were applied for in 1997 and granted in 2000. The Chatree Gold Mine commenced production in November 2001 after a 12 month construction period, on schedule and under budget. The processing plant has consistently exceeded design specifications.

Unloading Ore

An expansion to the Chatree plant was completed in December 2003 and increased throughput from 1-1.3 million tonnes per year (Mtpa) to 2 Mtpa, above the design capacity of 1.8 million tonnes per year.This expansion was completed on time and under budget.

Installation of a pebble crusher increased plant capacity to 2.4 Mtpa in June 2006. A further expansion to 5 Mtpa is planned for 2009-2010 to significantly increase gold production from new mining areas at Chatree North.

Conventional open pit mining methods are used at Chatree to extract gold ore from open pits.

Mining and haulage costs are critical items in open pit operations. Chatree introduced a local Thai earthmover to contract mining in 2001. This local Thai mining contractor, Lotus Hall, has then expanded to other operations in Laos and Thailand. This has resulted in significant business for local enterprises. This contract was updated in 2007 to allow for a new and expanded mining fleet, supported by Caterpillar, for increased production from the Chatree North mining areas.

Processing
Since commencing operations throughput has consistently exceeded the design capacity of the plant. The ore is passed through a jaw crusher where it is crushed down to less than six inches in size and then conveyed to a crushed ore stockpile which holds one week’s supply of plant feed.

Crushed ore is fed into a semi autogenous grinding (SAG) mill and ball mill where it is ground to the consistency of very fine sand (minus 75 micron size) and pumped to the cyclone tower prior to entering the cyanide leach (CIL) tanks.

Pouring gold

Gold and silver is leached from the ore by cyanide and is absorbed onto carbon grains.
The gold bearing carbon is collected and the metals are stripped from it and then passed through an electrowinning cell in which the metal is electroplated onto the cathode. The metal is recovered as sludge and is dried and smelted in a gas furnace before pouring into gold/silver bars.

Cyanide and water is recycled as much as possible with any excess cyanide being destroyed prior to disposal with the tailings (the residual fine ground rock) into the tailings storage facility. Cyanide levels have been historically around 5 ppm total cyanide upon entering the storage facility which is similar to levels found in a cup of instant coffee.

The gold/silver bars are shipped to a refinery in Hong Kong for final separation into saleable gold and silver (i.e. 99.999 fine gold).