Reference no: EM132560563

Question 1: Calculate the total drilling per month and drilling rate per minute from the following information:
Spacing of the drill holes: 5 m Burden of the drill holes: 4 m
Overburden to be removed per month: 200,000 m3 Hours scheduled per shift: 6
Shifts per day: 1
Drilling days per week: 5 Weeks worked per month: 2 Number of drilling units: 2

Question 2: How many drilling units are required to meet the overburden-preparation requirements of a surface mine, if the following information is provided?
Spacing of the drill holes: 7 m Burden of the drill holes: 5 m
Overburden to be removed per month: 500,000 m3 Hours scheduled per shift: 6
Shifts per day: 2
Drilling days per week: 5 Weeks worked per month: 3 Drilling rate: 20 meters per hour

Question 3: A house located at 300 meters from blast site, needs to be protected. Determine how much maximum explosive charge can be used to protect the house from blasting using square root scaled distance equation. The house can sustain blast vibration level upto 5 mm/s. Assume K: 690.84 and b: 1.65
Determine how much explosive charge can be used to protect the house, if it is 500 meters away from blast site.

Question 4: At an urban quarry, a drill and blast contractor has to produce +/-20,000 tonnes of blasted sandstone (2.70 t/m3), which will be fed to a 30 x 42 jaw crusher. The bench height is 15m and they use a hydraulic drill rig with 76mm drill bits. To obtain the required fragmentation, history has indicated that a powder factor of 0.80 or greater is required.
Assume an explosive density of 1.2 g/cc. Calculate the following:
a. No. of holes required
b. Total explosives required
c. A building is 500m from the blast. If the maximum mass charge per delay is 250kg, what is the greatest number of shot holes which can be detonated at the same time?

Question 5: Students are to undertake a tunnel blast design for the following conditions:

• Tunnel is 5.5 m wide by 5.5 m high
• Rock is granite with a UCS of 300 MPa
• Drill hole diameter is 51 mm, hole length is 4 m
• The cut is to contain 2 relief holes of 75 mm diameter
• Dry conditions are anticipated, ANFO to be used with a density of 800 kg/m3 and a powder factor of 0.6 kg/m3
• Nonel detonators are to be used

Students have to determine:

1. The design of the cut, including burden and spacing for each element of the cut.
2. Burden and spacing of the easer, perimeter and lifer holes
3. Stemming length required
4. Method of hole priming
5. Firing sequence timings for the holes
6. Explosive utilization

Results should be presented in a report format, including diagrams as required and details of calculations undertaken.

Question 6: An open pit blast consists of 1000 vertical blastholes. Bench height is 13 m and
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? (Note consider the emulsion only, i.e. do not consider primers).

Question 7: 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.

Blastholes are vertical and bench height is15m. 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?

Question 8: 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 2.5 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 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 are to be cored to provide both geological and geotechnical data.

Students are to determine the following:

a) Determine the total number of holes to be drilled

b) Determine to total meter's to be drilled assuming each drill hole is to be vertical with a total length of 110m.

Question 9: 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 and spacing.