JOHANNESBURG (miningweekly.com) – Gold processing operations at dual-listed Aureus Mining’s New Liberty mine, in Liberia, have been temporarily suspended owing to problems with the detoxification circuit in the process plant.

The gold miner on Tuesday said the detoxification circuit had not been operating to original design specifications, resulting in higher concentrations of weak acid dissociated cyanide in the process effluent.  

The plant had been operating with process water in a closed circuit, with zero discharge from the tailings storage facility (TSF); however, recent heavy rainfall had inadvertently resulted in a small overflow of effluent from the TSF into the wetlands area within the mining lease area. 

“Aureus is conducting remediation work to rectify the issues in the detoxification circuit and to manage future water discharge from the TSF,” the company said in a statement.

It added that its investigations, to date, had found no adverse impact on any human settlement, as the discharge had taken place within the mining lease and some 5 km from the nearest settlement. 

However, further investigations were in progress and, in view of this leakage, Aureus took the decision to suspend processing operations.

SRK Consulting staff were on site to assist Aureus’s engineering staff with the evaluation of the adjustments to be made to the waste neutralisation section of the detoxification circuit and the management of water discharge from the TSF in order for processing operations to recommence.

Aureus and its subsidiary Bea Mountain Mining Corp were coordinating work with the Environmental Protection Agency (EPA) of Liberia and the Ministry of Lands, Mines and Energy (MLME) and local downstream communities to mitigate against any environmental risks.

The EPA was reviewing and approving the proposed remediation work required to rectify the detoxification circuit and to manage future water discharge from the TSF.  

Approval from the EPA and MLME would be required before gold processing operations could resume.

During the suspension of processing operations, Aureus was implementing a mill reline and undertaking other scheduled preventive engineering maintenance and repairs, as well as modifications to the detoxification circuit.  

Mining operations were continuing, with ore stockpiles to be built up.