2029 INNOVATIVE COST MINIMIZATION FROM BLASTING TO PRIMARY CRUSHING BASED ON THE FRAGMENTATION OF BANDED IRON FORMATIONS *V.F. Navarro Torres1, F. Ferreira2, C. Araujo2, J. Miranda2, S. Rocha1 1ITV/Vale S.A., Brazil, (*Presenting author: vidal.torres@itv.org) 2Vale S.A., Brazil ABSTRACT The objective of this paper is to present an innovative methodology for minimizing the operating costs of drilling, blasting, loading, hauling, and primary crushing, and to introduce a new blast-design methodology for banded iron formations (BIFs), with very positive results in large iron-ore mines in Brazil and at Vale S.A. The cost-minimization methodology is based on a cost model that integrates P80 fragmentation with the operating cost models for drilling, blasting, loading, hauling, and primary crushing. This allows calibration for a given mine and, once the fragmentation range corresponding to minimum cost is determined, the blasting method is then selected to achieve that cost-minimizing fragmentation range. The search for the fragmentation range that minimizes costs led to research and the development of a new and compelling methodology building on the well-known fragmentation model proposed by Cunningham C.V.B. (1987). We modify and model the prediction of P80 as a function of the uniformity coefficient, rock factor, burden, spacing, bench height, explosive charge per hole, and the explosive’s relative mass strength, innovating the blast design by first sizing the hole diameter, then the burden based on the angle of break, and finally the spacing, considering bench height. To complete the design, procedures for sizing stemming and subdrilling are also presented. Additionally, a new model for quantifying delay timing is included, based on the travel time of detonation waves within the charged hole during detonation and the P-waves propagating through the rock mass between neighboring holes. The new methodologies have been tested and calibrated in Vale’s to large-scale iron-ore mines since 2020 through the present; for this article, a 2024 and 2025 case study at the Brucutu mine, producing approximately 40 Mt per year, showing excellent results and industrial application with highly significant economic gains. KEYWORDS Innovative, mining, primary crushing, cost minimization, blasting fragmentation, banded iron formation 1. INTRODUCTION The pursuit of lower operating costs and higher productivity in the mining industry makes it necessary to integrate the entire production chain, since minimum costs at a given stage do not necessarily correspond to minimum overall costs. In mining, the unit operations between drilling and blasting and crushing may be related to each other through the explosive’s specific energy or through fragmentation. Good fragmentation resulting from blasting can reduce excavation cycle time, increasing its productivity, and may also reduce the energy consumption of crushers, lowering costs at this stage. Thus, a scenario may arise in which increasing operating costs in the drilling and blasting phases is recommended in order to reach a point where the overall cost is minimized, or at least reduced.
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