Figure 4 – Sublevel stoping mine design for Hochfilzen mine. Stopes from mining panel 1 are blue, stopes from mining panel 2 are yellow and stopes from mining panel 3 are green. Stope dimensions and variable stopes height are indicated. Levels of where historical mine infrastructure is integrated are marked by light blue lines. The red area marks the area of influence of historical mining. The deposit is accessed via a main ramp which starts at the lowest level of the historical underground mine. This ramp facilitates connectivity between the individual sub-levels and infrastructural excavations as a crusher cavern or additional day access. From the main ramp striking drifts which are parallel to the ore bodies strike are excavated. From those drifts top and bottom drifts for mining the stopes are excavated. Long-holedrilling is done from the top drift. After blasting, remote controlled mucking is utilized by load-haul-dump (LHDs) vehicles. Depending on the stopes location underground trucks or LHDs transport the mined magnesite to nearest dump point. Material from elevated levels is transported to an ore pass leading to an ore bunker which is connected to a crushing cavern. The crushed magnesite can be transferred directly to the existing conveyor belt system. The conveyor ends at the mountain station of a cable way which transports the material directly to the processing plant 4 km away. 4.3 Backfill Management The availability of sufficient backfill material is imperative for the future operation of the Bürgl underground mine. The material used as backfill is obtained by processing and mining a historical waste dump in the vicinity of the mine. In consideration of the harsh alpine environment with sub-zero temperatures and substantial snowfall experienced in Hochfilzen during the winter months, operations at the waste dump are only feasible within the period not subjected to snowfall. However, it is imperative to note that underground operations are to be conducted throughout the whole year. An absence of backfill during the winter months, could lead to negative effects on the stability of the open stopes (which remain open throughout the winter months) and the mining sequence. The latter was demonstrated by simulations regarding the availability of backfill in GeoVia's
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