MINIMISING ORE DILUTION WITH ELECTRONIC BLASTING AND BLAST MOVEMENT MONITORING A CASE STUDY FROM BATU HIJAU

Ore and waste misclassification after blasting remains a major cause of dilution and revenue loss in open-pit mines. This case study reports a site-specific blasting framework implemented at the Batu Hijau open-pit gold mine, West Sumbawa, integrating electronic blasting systems (EBS), tailored blast geometries, and Blast Movement Monitoring (BMM) to preserve grade boundaries during excavation. Two complementary patterns drop-cut for ore and centre-cut for waste were designed in SHOTPlus and executed with i-kon II™ electronic detonators (8 ms nominal inter-hole timing) and Fortis™ Eclipse bulk emulsion. Blast movement was measured with BMM sensors and processed to update post-blast ore polygons. Results show a clear separation: horizontal displacement of 6.2 m in ore at PF = 0.46 kg/t versus 1.2 m in waste at PF = 0.18 kg/t, and heave of 4 m (ore) versus 1.6 m (waste). The approach created a distinct separation line and reduced ore spillage over the free face. The methodology demonstrates how precise electronic timing, energy partitioning, and movement measurement can jointly reduce dilution and improve downstream plant feed quality.