7 Rules of Thumb for Open Bit Blast Pattern

Drilling and blasting are all about putting the right amount of energy in the right place at the right time at minimum cost to achieve maximum control over the shot rock volume and the resulting particle size distribution in the muck pile

Mineral/Ore Mined using the Hardrock Blast hole Drill, which are Heavy duty Rotary and or Down-The-Hole rigs for Blast hole drilling. It can help client to achieve the best economic and social benefit.

Below is 7 rules of thumb for open bit blast pattern

1. Burden

• 25 to 35 hole diameters

2. Spacing

• size greater than 140 mm (5½”) 1.2 to 1.5 burden
• Hole size smaller than 140 mm (5½”) 1.5 to 1.8 burden

3. Stemming

• 0.7 to 1.3 burden.

4. Bench Height

• 40 to 50 hole diameters

5. Sub-drill

• 8 hole diameters
• 10 to 12 hole diameters for face rows

6. Powder factor

• Governed by:
  • Mine to mill process
• Budget
• Rock hardness

7. Hole diameter

• Governed by:
  • Required material size which is influenced by the loading and hauling equipment