Currently, a rectangular (square) grid of boreholes is used in iron ore pits, which in technical terms seems most appropriate due to the simplicity of creating, maintaining and accounting for blasting wells and short-delayed blasting (SDF) schemes. The drilling of blocks with a rectangular grid of wells also provides the possibility of a greater choice of groups and schemes of BHA. However, a comprehensive study of the action of blasting in rocks has shown that with a rectangular grid of wells the efficiency of explosive energy is far from optimal, as evidenced by a fairly large yield of oversize (5-10%) and the huge unevenness of the blast block, requiring additional costs of effort, money and time.
