iii. Cutting Time Sequence The use of electronic detonators was a key component to achieve an efficient evacuation of the cut, thanks to their high precision in the assignment of delays, which allows detailed control of the blasting development and obtain an optimal advance. One of the main challenges in the design of the sequence was the definition of the optimal detonation interval between holes, since there was no history of blasting in fronts of 8 meters in length using this type of initiation. To do this, previous experiences in production pits with the Sublevel stopping (SLS) method were taken as a reference, where the delays between holes vary from 5 ms. onwards. From this base, it was decided to cut the tests by a delay of 40 ms., progressively increasing the delay time until a sequence was reached that would ensure the complete evacuation of the fragmented material before the firing of the next hole. The initiation sequence was designed to cut from the central cut hole, progressing to the holes closest to the relief holes, following a counterclockwise spiral pattern, adapting to the structural conditions of the massif. As for the loading scheme, ANFO was used as the column charge in 54 mm holes, and 11/2" x 7" cartridge emulsion as the priming charge, initiated by three electronic detonators per hole, distributed along the charge to ensure uniform and reliable initiation along the axis of the explosive column. Table 2 – Times in milliseconds at cut. Description No. of Holes Loaded Time Hole - Hole. Total Time Cut Test Sequence 1 5 40ms. 185ms. Test Sequence 2 5 100ms. 425ms. Test Sequence 3 5 150ms. 600ms. iv. Evaluation of the number of primers. The placement of three baits distributed along the axis of the 8.0 meters long drill is based on the need to ensure a consistent propagation of the shock wave, a key condition to achieve a homogeneous distribution of explosive energy throughout the load column. This configuration serves a dual technical purpose: • Optimization of uprooting: the presence of multiple starting points favors a controlled and uniform breakage of the rock mass, which contributes to the formation of a better free face and, consequently, to a more efficient fragmentation in the uprooting area.
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