### Backfilling

Backfilling of stopes is performed by utilization of Cavo 310 load and haul machine. Maximum backfilling transportation distance is illustrated in Figure 24 and is around 125m at the level L+1600m.

**Figure 24** Longest backfill distance

Volume of material that has to be installed in the stope:

$$V=w\cdot h\cdot {{l}_{bh}}=3\cdot 2.5\cdot 1.6\approx 12{{m}^{3}}$$

Where:

W – width of stope (3m)

h – height of stope (2.5m)

l_{bh} – length of blasthole (1.6m)

Total number of cycles necessary to transfer this amount of ore to the ore pass is:

$${{N}_{c}}=\frac{12{{m}^{3}}}{{{V}_{cb}}\cdot 0.9}=\frac{12}{1\cdot 0.9}\approx 14 cycles$$

Where:

V_{cb} – Volume of Cavo 310 body (1m^{3})

Loading of Cavo 310 with backfill material takes following time:

$${{T}_{l}}=\frac{{{V}_{cb}}\cdot 0.9}{{{V}_{b}}}\cdot {{t}_{l}}=\frac{1{{m}^{3}}\cdot 0.9}{0.13{{m}^{3}}}\cdot 15s\approx 100s$$

Where:

V_{cb} – Cavo 310 body volume

V_{b} – bucket volume

t_{l} – time for loading of one bucket

Total driving time can last up to:

$${{T}_{D}}=\frac{{{L}_{T}}}{\upsilon }=\frac{2\cdot 125m}{1m/s}=250s$$

Where:

L_{T} – maximum total driving distance (2 x 125m see Figure 24)

$\upsilon$ – driving velocity (1m/s)

For dumping, maneuvering and all unexpected pauses 40s is left within each cycle and therefore total duration of one loading and hauling cycle is:

$${{T}_{BFC}}=250s+100s+40s=390s\approx 6.5\min \to 7\min $$

Total duration of backfilling of one stope takes up to:

$${{T}_{BF}}={{T}_{BFC}}\cdot {{N}_{c}}=7\min \cdot 14=98\to 100\min $$

**Table 3** Gantt chart for backfilling