Mining Operations

The Shahumyan underground mine is a polymetallic deposit from which separate copper and zinc sulphide concentrates, containing gold and silver by-products, are produced. Lead mineralization is also present but is not economic at this time.

Processing

A crushing and flotation plant has been developed at Shahumyan using typical Soviet era construction and layouts. After primary and secondary crushing, through either of the polymetallic or Centralni crusher units (crusher product size of 30-50mm), material is transported to a storage area by conveyor to supply the concentrator. The Shahumyan ore is then fed by conveyor to a rod-mill, followed by a ball mill and a small re-grind mill, as necessary. The primary cyclone overflow feeds the flotation circuit consisting of conventional Russian Denver style flotation cells to differentially float a gold rich copper concentrate and a zinc concentrate with lesser gold and silver concentrations. There are three main thickeners, each 24 metres in diameter, one for each type of concentrate produced and a backup system used during repair and maintenance. A small eight meter in diameter thickener serving the uncommissioned lead concentrate circuit will be used to process mine water for use as makeup water in the mill circuit along with reclaim water piped from the Geghanush TMF to the mill. Thickened concentrates are then dewatered using vacuum filters producing a copper (with significant gold and silver) concentrate and a separate high grade zinc (containing smaller quantities of gold and silver) concentrate.

Overall gold recovery is approximately 90%, with between 12% and 16% reporting to the zinc concentrate. Onsite testing continues to reduce this with the corresponding increase into the copper concentrate. Overall silver recoveries have improved to 90%, with 72% reporting to the copper concentrate and 18% reporting to the zinc concentrate.