The Sigma-Lamaque Complex is comprised of the Sigma and Lamaque underground mines, the Sigma open-pit mining operations, the Lamaque open-pit project and the Sigma mill.

In November 2002, an expansion of the mill to a nominal capacity of 5,000 tonnes of ore per day was completed by the previous mine owner.  

The mill currently operates 24 hours per day, 365 days per year, with an expected availability of 92.6%, or a design capacity of 5,400 tonnes of ore per day. The projected life-of-mine mill feed grade is 1.8 g/t Au and the rate of gold recovery is on the order of 96%.

Ore is transported by rear-dump haulage trucks from the open pit's mining operations and dumped directly into a receiving hopper, after which it is crushed and transferred to an external stockpile. From the stockpile, ore is transported to a 26-foot diameter SAG mill, where primary grinding occurs. Discharge from the SAG mill is pumped to a common primary cyclone cluster, and then into two ball mills installed in parallel for further size reduction. A rod mill completes the secondary grinding circuit.

After passing through a thickener process, the resulting slurry is sent through a 24-hour cyanide leach circuit.

From the cyanidation circuit the slurry discharges by gravity to the carbon-in-pulp (CIP) circuit. The CIP circuit consists of seven mechanically agitated tanks. Slurry containing loaded carbon from the first CIP tank is pumped to a vibrating screen. Water spray washes the carbon as it passes across a loaded carbon screen. Washed carbon then discharges by gravity to a loaded carbon screen, and is pumped to a carbon-stripping circuit.

Gold is recovered using an electrowinning cell fitted with stainless steel mesh cathodes. Cathodes are removed from the electrowinning cell as required and dried. The dried cathodes are mixed with flux and smelted to recover gold bullion.