The Ban Houayxai Project is a vein hosted, structurally controlled gold-silver deposit of Permo-Carboniferous age (285Ma) in the north of the Lao People’s Democratic Republic. Mineralised veins are predominantly hosted within intermediate volcanics which have been subject to greenschist facies metamorphism and structurally juxtaposed against a siliciclastic package of lower metamorphic grade. The siliciclastic package contains mineralisation hosted within bodies of volcaniclastic siltstone and volcanogenic sandstone. The gold tenor of mineralised veins (quartz + pyrite ± carbonate ± base metals) within the Ban Houayxai deposit improves with increasing intensity of deformation.

The Ban Houayxai Process Plant flow sheet includes primary crushing, SAG milling, pebble crushing, ball milling, gravity concentration, CIL, tails thickening and cyanide detoxification. Initial processing involves the treatment of oxide ore at throughput rates equivalent to 5.2 mtpa. Once oxide ores are exhausted throughput rates on harder transition and primary ores will be 4.0 mtpa.

The gravity circuit includes a gravity concentrator and an agitated leach tank for coarse gold extraction ahead of the CIL circuit. The CIL circuit consists of 6 tanks in series.

The associated carbon circuit has been constructed to recover 18 tonnes of carbon per day. Precious metal desorption is achieved using a dedicated AARL split acid wash and elution circuit. Barren carbon is regenerated utilizing a dedicated carbon regeneration kiln. The circuit is operated in a series of batch operations at a rate of one to two 9 tonne strips per day. Precious metal recovery is achieved using 7 electro winning cells in parallel. Gold and silver bearing sludge is filtered and oven dried prior to smelting.