GeoProMining (GPM) has successfully increased recovery from sulphide concentrates in its Ararat plant from 20% to more than 95%, defying expectations and targets, according to Glencore Technology. The plant was commissioned in June 2014 and achieved full capacity after three months.

GPM owns and operates the Zod gold mine and Ararat processing plant in Armenia to produce gold and silver bullion. To expand, GPM needed to treat the underlying sulphide material at the Zod mine, which achieved around 20% to 30% gold recovery through their existing conventional carbon-in-leach (CIL) flowsheet.

In 2010, the company approved a refurbishment project to increase crushing capacity to deal with the harder ore, and a refurbishment and re-commissioning project for the existing flotation plant. GPM also added the installation of a new Albion Process plant for the oxidation of the sulphide concentrate prior to its treatment in the existing CIL plant. The new flowsheet would be configured so the CIL would treat flotation tailings and oxidized residue from the Albion Process.

The Albion Process is an atmospheric leaching process developed and owned by Glencore Technology. It uses ultrafine grinding to reduce the activation energy needed in oxidation of the sulphides, so that it can occur under atmospheric conditions. The leaching occurs in an agitated tank that uses HyperSparge supersonic gas injectors to boost oxygen capture efficiency.

Glencore Technology was engaged to design, supply and commission the Albion Process and to provide installation supervision assistance.

The design basis for the Albion Process at GPM was oxidation of 100,000 metric tons per year (mt/y) of concentrate to give an overall production of 100,000 ounces per year (oz/y) of gold from concentrate and flotation tailings. The design recovery of gold from the Albion residue was 92%, but the plant frequently achieves more than 95% recovery with an overall plant-wide design recovery of 86%, commonly achieving 88%.

The refurbishment project was commissioned in June 2014, with ramp-up occurring for the remainder of 2014. The plant has achieved and exceeded nameplate production, treating in fact 120,000 mt/y concentrate with an overall production of 120,000 oz/y.

Moreover, GPM successfully achieved an overall 88% plant-wide recovery exceeding the 86% design target due to better than design performance in the Albion Process. The grade of concentrate has been more or less stable, and increased production might normally be expected to decrease as equipment is stretched. But in GPM’s case, they’ve successfully kept the recovery above design using the Albion Process.

GPM are currently evaluating an expansion project comprising a second line of an Albion Process Plant.