Tembang Mining

The current Tembang life-of-mine plan is based on the five open pit mines at Berenai, Asmar, Tembang, Buluh-Siamang and Bujang, with the Belinau underground mine developed via decline from the former Belinau open pit.  

The underground mine plan for Belinau provides access to the vein lenses via decline from surface. The decline has been developed from inside the existing Belinau open pit, well above the pit bottom to deal with high intensity rainfall events, which are common in the region. The total length of the decline will be approximately 1,360 metres with a 1-in-7 gradient taking the mine to a depth of around 235 metres. Mining is by long-hole stoping with backfill, retreating from the vein limits back to the access crosscut. The mining method is a combination of top down conventional stoping along to the west and to the east and a slight variation to the typical Avoca or bench stoping method, with a 3m bench cut into the ore drive floor on each planned cemented aggregate fill (CAF) level. The mining method reflects the vertical nature of the wall rock and competent host rock either side of the vein. It is expected that approximately 40% of ore production will be from development and 60% from long-hole stoping. Development and operations at Belinau are currently on an ‘owner-operator’ basis.

The open pit mining strategy is based on the Berenai and Asmar pits providing a lower grade “base load” mill feed so mill capacity is maximised. The higher grade Buluh-Siamang Pits and the Belinau underground progressively provide higher grade feed to the mill. The strategy of multiple feed sources enable both flexibility in ore supply and de-risks the project in terms of not being reliant on one source of ore production. The open pit designs were optimised using a gold price of US$1,100 per ounce. Open-pit mining operations are being conducted by contractors using hydraulic excavators and articulated all-wheel drive trucks.