FEDERATION UNIVERSITY AUSTRALIA
School of Engineering, Information Technology & Physical Sciences
ENGIN5514: Production Drilling and Blasting
Tutorial Questions – 40% of course marks Submission due date: Saturday, 09th July 2022
- Define the following terms with reference to drilling:
- Thrust (5 marks)
- Percussion (5 marks)
- Rotation (5 marks)
- Indexing (5 marks)
- Flushing (5 marks)
- Rifle bar (5 marks)
- Pull down (5 marks)
- Diamond drilling is used extensively in mining, but for what purpose (10 marks)? Describe the methods available for core recovery (10 marks).
- Describe in detail a Down the Hole Hammer Drill (10 marks). What particular advantages does this type of drill have over other percussive methods of drilling (10 marks)?
- What is the drillability of rock (5 marks) and which factors influence drillability (5 marks)?
- What types of geological (5 marks) and geotechnical data (5 marks) can a core drilling program provide?
- What is reverse cycle drilling (5 marks)? How does it differ from normal drilling (5 marks)?
- How is the Drilling Rate Index (DRI) measured (10 marks)?
- An open pit blast consists of 1000 vertical blastholes. Bench height is 13 m and 1.5 m of subdrilling is undertaken. The holes have 3.5 m of stemming. Blasthole diameter is 250 mm, the burden is 7 m and spacing is 5.5 m. An emulsion explosive of specific gravity 1.15 is used. What is the powder factor (15 marks)? (Note consider the emulsion only, i.e. do not consider primers).
- An open pit mine employs ANFO at a density of 0.9 g/cc as its explosive. Given the following details, determine the blasthole spacing (15 marks).
Blastholes are vertical and bench height is 15m. Burden and spacing of blastholes are B = 1.2 S. The Density of the rock is 2.7 gm/cc
The powder factor is 0.8 kg of explosive per m3 of rock. The hole diameter is 250 mm.
Stemming column length is 4 m and subdrill is 1.5m.
If ANFO has a cost of $1500 per tonne, what will be the cost of explosives per tonne of rock (10 marks)?
- Geophysical prospecting has discovered a potential copper-gold mineral deposit on an exploration lease. The results of the geophysical exploration program indicate the potential for a 20m thick ore deposit over an area of 3 km in length in an east-west direction and
- km in length in a north-south direction averaging 80m below the ground surface, which is located in an area of flat topography. It has been decided to undertake a further exploration of the area using a 500m square grid and core drilling. The chief geologist has decided that as the deposit may be developed by surface mining operations that the entire length of the boreholes is to be cored to provide both geological and geotechnical data.
Students are to determine the following:
- Determine the total number of holes to be drilled (5 marks)Determine to total metre’s to be drilled assuming each drill hole is to be vertical with a total length of 110m (10 marks)
- What is the importance of stemming in relation to blasting (10 marks)?
- A new coal mining operation is to be worked employing surface mining using blasting to clear an overburden of Shale using 120 mm holes and 12 m benches. Dry rock conditions are anticipated and the decision is to use bulk ANFO with emulsion cartridges as a primer. A staggered drilling pattern with S = 1.3 B is to be employed. If density of compacted ANFO = 0.85 g/cm3 and PF = 0.9 kg/m3, calculate the burden (10 marks) and spacing (5 marks).
- Using explosives in sulphide ores and hot reactive rock poses certain difficulties, what are these and what steps can be taken to minimise their impact (10 marks)?
- Monitoring of blasts is undertaken for a variety of reasons, discuss why this is the case (10 marks).
- Describe briefly the methods of blast monitoring available and their range of application (15 marks).
- Define the following:
- Paddock blasting (5 marks)
- Cushion blasting (5 marks)
- Decoupling (5 marks)
- Lifters (5 marks)
- Easers (5 marks)
- Primer (5 marks)
- Throw blasting (5 marks)
- Describe with the aid of diagrams typical blasting rounds for a shaft sinking in watery (10 marks) and highly jointed strata (10 marks).
- Describe an electronic system of blast initiation (10 marks). What are the advantages and disadvantages of this system (10 marks)?