2032 2.2 Blasting fragmentation model for banded iron formations At ITV/Vale S.A., Navarro Torres V.F. (2020–2025) developed and proposed an innovative model for the fragmentation of rock masses in banded iron formation (BIF), represented by Equations 6 based in Kuz-Ram model, 7, 8, 9, and 10 and Table 1, which is expected to be published in September of 2026. BT< =2,32& #Fô[FHI]<,T 2ö !! MõNOPQ7 <,ÇZ (6) H = 79,4 ∗ BN0HW −350,6 =TU VWX ≤ 120 ?0@, friable lithology (7) D = 68,4*Ln.Pmh-262,3 for UCS=120-225 MPa, semi-compact lithology (8) H = 57,4 ∗ BN0HW −174,0 =TU VWX ≥ 225 ?0@, compact lithology (9) Table 1 – Blast design sizing methodology for banded iron formations (BIF) PARAMETER COEFICIENTE LITHOLOGY AND COMPRESSIVE STRENGTH (MPa) MODEL Friable Semi-compact Compact Very compact 50 -125 125-225 225-300 300-400 Density (9) g/cm3) and explosive type 9 2<0,9 0,9≤92 <1,2 92 >1,2 ANFO ANFO, 70/30 70/30, 100 Emulsion 100 A (m) Ka 0,64 0,56 0,48 0,42 A=KaD E (m) Ke 1,45 -2,0 1,23-1,45 1,15-1,23 1,0-1,15 E=KeA T (m) Kt 0,7 -1,0 0,7 -1,0 0,7 -1,0 0,7 -1,0 T=KtA J (m) Kj 0,1-0,2 0,1-0,2 0,1-0,3 0,1-0,3 J=KjA Angle (°) 2Ɵ 75 -90 65-75 60-65 60-65 J: subdrilling !1 =10002q N@ úO P + ç(N@P)2? á2í9,; Q? 7 (10) Where: X90: mean fragment size [cm] n: Cunningham uniformity index (0,7 - 2,0) Ar: rock factor (2,3 to 7,8) A: burden (m) E: spacing (m) H: bench height (m) Qe: explosive charge [kg/hole] Sanfo: explosive energy per unit weight (%) based in ANFO D: hole diameter (mm)
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