Regis Resources is set to develop an underground mine under the Garden Well open pit in Western Australia after receiving board approval and completing a positive feasibility study (FS).
The study includes a probable ore reserve of 900,000 tonnes at 3.4 grams per tonne of gold for 98,000 ounces.
Regis plans to mine an additional 92,000 ounces of gold from the inferred mineral resources.
The company expects underground development to start in the March 2021 quarter, with processing of first underground ore scheduled for the December quarter that year.
Regis managing director Jim Beyer said the new underground mine would be a key element for the Duketon operation to become a reliable 400,000 ounces per annum producer.
“We believe that the approved Garden Well underground is not only a robust investment in its current form but just as importantly has the potential to increase life and value through down plunge exploration,” he said.
The underground development will take an estimated $38 million of pre-production capital.
It will extend mining of the Garden Well mineralisation below and to the south of the existing open pit.
Regis plans to use conventional long hole open stoping mining methods over four years, in anticipation of achieving annualised production rates of around 600,000 tonnes a year once stoping production is established.
The Garden Well deposit is around 100 kilometres north of Laverton in the Duketon Greenstone Belt.
Production at the Garden Well open pit mine commenced in March 2013, and is expected to continue until late 2025.
Garden Well is the largest gold discovery in the Duketon area and is part of Regis’ Duketon South operations.
In the 2020 fiscal year, Regis delivered 259,858 ounces at the Duketon South operations at an all-in sustaining cost of $1218 per ounce.