This paper investigates the viability of an increase in waste rock storage by backfilling the Falcon pit and extending the portal of the Fosterville gold mine, located in Bendigo, Australia. The structure will maintain the current access to the tunnel whilst developing a fillable void. Once completed the project will allow for a total increase of 900,000 cubic metres of storage. Furthermore, a finite element study has been conducted to investigate the structural performance of a proposed design using corrugated steel sheets. Stresses and displacements are studied taking into account various design factors such as steel properties and geometry. Results demonstrate the location of critical stress values according to the proposed design. The selection of optimum steel geometry is also investigated with regards to the factor of safety.
Gold mining has been a part of Bendigo’s history since the discovery of the first deposits of alluvial gold by Kennedy and Farrell in 1851. Fosterville, one of the gold mines in the area, is located 20 kilometers out of Bendigo, Australia.
Gold was first found in Fosterville in 1894 and during 9 years of operation 0.87 t of gold was produced. Mining of shallow oxide opens pits re-commence in 1991 using a heap leach operation process, which ceased in 2001. A feasibility study into sulphide gold-bearing ore processing was completed in 2003 and the first stage of commercial production began in 2005. The operation started by extracting low-grade, near-surface mineralization (Table 1) (T Fuller & Hann, 2019).
Fosterville’s deposit is hosted within an interbedded turbidite sequence of sandstones, siltstones and shales. The primary gold mineralization follows disseminated arsenopyrite and pyrite forming as a selvage to veins in a quartz-carbonate vein stockwork. The deposits have average grades of 5-10 g/t Au (Fig. 1). The sulphide mineralization is overprinted by visible gold within-host quartz veins. Visible gold is becoming more frequent at depth and with the discovery of the Eagle zone and soon after the Harrier zone (Fig. 1), these deposits are high-grade (2.29 Mt @ 23.1 g/t Au) (Table 2), reaching the highest assays seen in recent history, 191 g/t Au over 2.55 m in the Swan zone. Visible gold is observed within quartz-carbonate veins, with a noticeable increase in recent years as underground mining has advanced deeper. Visible gold particles are predominantly specks (up to 3mm), however more rarely they can be > 5mm (T Fuller & Hann, 2019).
