2035 Table 2 – Technical-economic parameters de blasting a primary crushing da Brucutu mine Operation Parameter IF ISC IC Drilling and Blasting $p ($/m) 31,66 51,56 74,78 H (m) 10 10 10 J (m) 1,5 1,4 1,3 Qex (kg/furo) 261,9 269,9 277,8 $ex ($/kg) 1,12 1,12 1,12 $ai ($/furo) 34,78 34,78 34,78 Ar 5 7 10 RWS (%) 109 109 109 n 1,533 1,501 1,524 pr (g/cm³) 2,9 3,3 3,7 Loading $c ($/h) 1120,84 1120,84 1120,84 a 9,71 10,49 12,15 b 0,05 0,05 0,05 Teta (°) 87,5 87,5 87,5 td (s) 5,69 5,62 3,95 Uc (%) 0,6117 0,6117 0,6117 Lc (t) 48,77 48,77 48,77 Primary Crushing $bp ($/h) 4759,57 4759,57 4759,57 Wi (kWh/t) 8 12 16 d80bp (mm) 282 282 282 Pbp (t/h) 4500 4500 4500 $e ($/kWh) 0,031 0,031 0,031 f ($/kWh) 1,00 1,00 1,00 Hauling $t 406,32 406,32 406,32 p 5 5 5 tv min 12,67 12,67 12,67 td min 0,67 0,67 0,67 te min 7,86 7,86 7,86 Lt t 243,86 243,86 243,86 Ut 0,8916 0,8916 0,8916 By applying Equations (1) to (5) using the technical–economic data in Table 2, it is possible to obtain the total cost curves (US$/t) as a function of X80 fragmentation (cm) for Friable Itabirite (FI), Semicompact Itabirite (SCI), and Compact Itabirite (CI). The results show that, at the Brucutu mine, the itabirite fragmentation range that minimizes the costs of drilling, blasting, loading, hauling, and primary crushing operations varies from 28 to 32 cm. This result indicates that fragmentation between 28 and 32 cm minimizes the costs of the drilling– blasting–loading–hauling chain to 4.8 US$/t in friable lithologies, 5,2 US$/t in semi-compact lithologies, and 5.6 US$/t in compact lithologies. Therefore, proper blast design is extremely important to achieve the
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