Ore Processing

The process plant consists of a conventional crushing plant with a capacity of 17,500 tpd, a conveyor that can handle up to 20,000 tpd, a heap leaching facility, a carbon-incolumn circuit and an electrowinning and refining plant.

Crushing takes place in three stages. Ore is first crushed to 80% passing 15 cm in a primary jaw crusher. Ore from the primary crusher is then conveyed to a coarse ore stockpile with a storage capacity of 10,000 tonnes. Two apron feeders take the ore from the stockpile to feed the secondary crusher via conveyor. Secondary throughput reports to two tertiary crushers that crush to 0.9 cm. After crushing, the ore reports to the leach pad via an overland conveyor.

The 1,600 meter long conveyor transports the crushed ore to the leach pad area southwest of the crusher, where ore is stacked and leached. The heaps are underlain by an impermeable plastic layer on top of 0.4 meters of compacted clay. To dissolve gold in ore, cyanide solution is applied to the ore on the leach pad using a drip tube irrigation system. Gold-bearing solution is channeled to the pregnant solution pond and is then pumped to the carbon-in-column circuit where gold is recovered from solution. The barren solution is then recirculated to the heaps with added cyanide. Dore bars are produced on site and transferred to a third-party refinery for final recovery of gold and minor amounts of silver.

Power & Water Supply
The power plant consists of six 1,000-kilowatt generators and has been operating since June 2005. Water for the operation is pumped from the Mulatos River at 950 meters above sea level. In addition to the river water, the Company has constructed a dam south of the waste dump that can impound up to 309,000 m3 of water and is less expensive to draw from than the river source because of its higher elevation of 1,270 meters.