GeoProMining LLC (GPM) successfully increased recovery from sulphide concentrates in its Ararat plant from 20% to over 95%, defying expectations and targets. 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.
In order to expand, GPM needed to treat the underlying sulphide material at the Zod mine which only resulted in around 20 to 30% gold recovery through the existing conventional CIL flowsheet.
In 2010, GPM approved a refurbishment project at the Zod mine and Ararat processing plant – in increased crushing capacity to deal with the harder ore and a refurbishment and re-commissioning of the existing flotation plant. Added to this was the installation of a new Albion ProcessTM plant for the oxidation of the sulphide concentrate prior to its treatment in the existing CIL plant. The new flowsheet would be configured such that the CIL would treat flotation tailings and oxidised 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 HyperSpargeTM 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 GPM’s Albion Process was oxidation of 100,000 t/y of concentrate to give an overall production of 100,000 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 over 95% recovery with an overall plant-wide design recovery of 86% but 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 t/ya concentrate with an overall production of 120,000 oz/y.
Further, 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, it has successfully kept recovery above design using the Albion Process.
GPM is currently evaluating an expansion project comprising a second line of an Albion Process plant.