The mine in this example must blast about 100,000 tonnes in a single blast. The benches are hard rock. Design a drillhole pattern and blast for the mine, assuming 15 m benches. The mine has sensitive structures 800 m from the blast site for which peak particle velocity (PPV) must not exceed 1mm/second. Take that into account when designing the blast/drill. You also want 95% of your rock to be under 55 cm size. Also need an Excel sheet made or code to do it.

1. From the base design, decrease the spacing by 10%. What is the effect on particle size (at 95^th percentile), PPV, powder factor (PF), and holes needed to get the desired tonnage?
2. Make one change to your base design to bring down the PPV, but not increase the particle size. What is the effect on powder factor? Does it make sense?
3. What changes will you make to your base design to bring down the number of holes, but not increase the particle size, or PPV.
4. What are some of the broad relationships you noticed between spacing, burden, PF, 95^th percentile rock size, and number of holes?