Gekko Systems designed and built this 50-mt/h modular gold plant at Aurelia Metals’ Hera project in Australia.

Gekko Systems recently reported the formal acceptance of the Hera processing plant by Aurelia Metals Ltd. The handover of the plant followed the successful completion of performance trials by Gekko that included a continuous 240-hour operating run, processing 9,600 metric tons (mt) of ore, including a continuous 12-hour run at 50 mt/h, as well as equipment performance tests and grinding and environmental compliance tests.

Aurelia’s Hera-Nymagee project is located about 100 km southeast of Cobar in western New South Wales, Australia. The company began full-scale development in March 2013, following completion of a A$158 million funding transaction with Glencore.

Gekko described the plant project as “the most significant” that it has undertaken; it began in May 2013 when Gekko was awarded the contract to design, manufacture, install and commission the 50-mt/h gold polymetallic processing plant. Prior to receiving the contract, Gekko performed test work for Aurelia Metals and received positive feedback on a low-energy, cost-effective flowsheet.

At the time of the Hera project acceptance announcement, Gekko Systems’ co-founder and technical director, Sandy Gray, said, “The plant has been running successfully for several weeks in a stable condition. More than 1,000 tons of lead zinc concentrate have been produced along with several gold and silver bars. This project includes plenty of new technology to Gekko including Vertimill, Derrick screens and Merrill Crowe.”

The major components of the plant design are a three-stage crushing circuit and coarse grind to 250 microns consisting of a jaw and cone crusher, vertical shaft impactor (VSI) and a Metso Vertimill in closed circuit with a Derrick screen; gravity gold recovery circuit; rougher flotation at 250 microns before regrind of rougher flotation concentrate to 38 microns; cleaner flotation; cyanide leach of cleaner concentrate to leach gold and silver; zinc precipitation process to produce Au-Ag doré; leach residue filtration and stockpiling of Pb-Zn concentrate; and a peroxide cyanide destruction circuit.