In November 2025, ArcelorMittal’s Mining Exploitation in Canada carried out a major single mining blast at the Mont-Wright mine in northern Quebec. A total of 8.2 million tonnes (Mt) of hard rock was successfully fragmented in a single drilling pattern, representing an unprecedented scale in surface mining. The blast required 2855 drill holes and over 3 million kilograms of emulsion, covering an area of 1000 m × 335 m and breaking more than 3.1 million m3 of rock. Proximity to Fermont City and vulnerable quartz zones made vibration control and pit wall stability critical concerns. To address these challenges, advanced 4D blast design technology was implemented to optimise emulsion loading, positioning, and timing, ensuring efficient rock fragmentation while minimising vibration amplitudes. The blast timing was distributed in an inverse V configuration, leveraging two free faces to enhance rock breakage and mitigate the concentration of vibration on the final pit wall. A comprehensive instrumentation and monitoring program was deployed to assess the geotechnical response of the pit walls. Time Domain Reflectometry (TDR) and piezometer (PZ) measurements were recorded both before and after the blast to evaluate stress redistribution, pore pressure changes, and micro-deformation within the rock mass. Additionally, post-blast slope stability monitoring with slope stability radar (SSR) provided continuous real-time measurements of slope displacement, confirming the structural integrity of the walls and enabling immediate validation of the blast performance. In this regard, numerical analyses were performed using UDEC and FLAC3D to evaluate the stability of the rock slope and to compare the predicted displacements with radar monitoring data, while accounting for the effects of the excavation damage zone (EDZ). The event demonstrates that modern mining methods can safely manage large-scale hard rock blasting while maintaining pit stability and minimising vibration impacts.