OFFICIAL formed by 8 m wide panel pillars between stopes; cross section = 1 186 m² Figure 6 – Examples of stope and panel layout; left: Option 1 – circular shaped stopes; right: Option 3 - hexagonal-shaped stopes; reduced extraction; honey-comb structure through panel pillars A mining block comprises 12 stopes which are grouped in 3 rows with 4 stopes each. The outer boundary of the blocks follows the shape of a parallelogram. This shape is driven by the alignment of the main drifts in the development levels. Rationale of the stope design using different layouts is that the center points of all stopes, i.e., the position where the initial raise is drilled, stays exact at the same position, irrespective of the shape of the later developed stope. The basic stope layout follows a grid with 45 m grid-point spacing. All secondary and tertiary developments in a block are identical for the three stope layouts. Typically, a block will be prepared for future stoping by developing raises, extraction and haulage drifts. Following the concept of the flexible stope layout, it is possible to decide after the block’s development and based on the in situ observation of the rock mass conditions and ore quality during raise boring and drifting which stope layout should be implemented best. Table 2 shows the key figures for the three different stope layouts. Stope sizes, recovery rates, number of stopes to be mined during full production of 5 Mio t in 10 and 30 years, respectively, are compared in Table 2. Table 2 – Key figures for different stope layouts Option 1 Option 2 Option 3 Stope cross section [m²] 1 582 1 754 1 186 Stope height [m] 300 300 300 Stope volume [m³] 397 533 431 291 299 896 Recovery rate (2D) 47% 52% 36% Nominal production [Mt/y] 5.0 5.0 5.0 Stopes to be mined in 10 years 27 25 36 Stopes to be mined in 30 years 99 91 131
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