Question 1: What are the main purposes of drilling rock in Mining operations?
Question 2: Define the following terms with reference to drilling:
• Thrust
• Percussion
• Rotation
• Indexing
• Flushing
• Rifle bar
• Pull down
Question 3: Diamond drilling is used extensively in mining, for what purpose? Describe the methods available for core recovery. What impact does the number of core barrels have on core recovery?
Question 4: An open pit mine employs ANFO at a density of 0.85 g/cc as its explosive. Given the following details, determine the blasthole spacing.
• Blastholes are vertical and bench height is 11m.
• Burden and spacing of blastholes are the same, i.e. B = S.
• The specific gravity of the rock is 2.5.
• The powder factor is 0.5 kg of explosive per m3 of rock.
• Hole diameter is 225 mm.
• Stemming column length is 3 m and subdrill is 2m.
If ANFO has a cost of $950 per tonne, what will be the cost of explosives per tonne of rock?
Question 5: Describe in detail a Down the Hole Hammer Drill. What particular advantages does this type of drill have over other percussive methods of drilling?
What is the drillability of rock and which factors influence drillability?
Describe in detail the four essential characteristics of drill holes.
Question 6: Describe briefly the main properties of explosives.
Question 7: ANFO is used widely in mining applications, what are its advantages over other types of explosives and what disadvantages does it have.
Question 8: In underground blasting it is required to provide a free face or cut in the blasting pattern, why is this required? Describe two such cuts used. Detail the aims of a drilling pattern used in a blasting round.
Question 9: With respect to blasting, what does VOD mean? What does VOD actually measure? What range of VOD’s would you expect in modern commercial explosives? What is the maximum VOD you would expect from ANFO? How does blasthole size affect the VOD of ANFO?
Question 10: Modern explosives are made up of oxidisers, fuels, sensitisers and other ingredients. Give examples of these for:
• ANFO
• Heavy ANFO
• Emulsion