Blasting Techniques and Factors Quiz

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Questions and Answers

What type of blast pattern has drilled spacings larger than drilled burdens?

Square blast pattern

Rectangular blast pattern (correct)

Circular blast pattern

Staggered blast pattern

What dictates the movement and fragmentation of a shot in millisecond delay blasting?

Timing between holes in a row and between rows (correct)

Depth of the drilled holes

Rock density at the blast site

Type of explosive used

What is the typical range of gas pressure created by a blast that moves the rock out from the blast face?

200 to 250 ft/s

25 to 50 ft/s

100 to 150 ft/s

50 to 100 ft/s (correct)

What effect does an increase in the number of rows have on the movement of rock in a blast?

Reduces relief toward the free face Signup and view all the answers

What is the formula for Powder Factor?

$\pi \times \rho_e \times d^2 \times \frac{1}{4000} \times B \times S$ Signup and view all the answers

What is the loading density for a charge diameter of 152.4 mm?

15.5 kg/m Signup and view all the answers

What is the formula for the loading density interpolation?

$\frac{16.88 - 15.42}{159 - 152.4}$ Signup and view all the answers

What is the range for small diameter blasthole drilling diameter?

65 - 165 mm Signup and view all the answers

What are the three main factors that influence rock breakage?

Drilling, explosives, and geology Signup and view all the answers

What does the formula $f(x) = -4(x + 3)^2 + 2$ represent?

Quadratic function Signup and view all the answers

What is the formula for the length of bottom charge in large diameter blasthole?

H cos $\beta$ Signup and view all the answers

What influences the selection of explosives according to the text?

Field conditions Signup and view all the answers

What is the formula for powder factor (q)?

$q = \frac{We}{Vr}$ Signup and view all the answers

What does the powder factor value range from for normal bench blasting?

0.1 to 0.7 kg/m3 Signup and view all the answers

What is the loading density in the example calculation for open pit mine bench blasting?

15.5 kg/m Signup and view all the answers

What is the charge length in the example calculation for open pit mine bench blasting?

10.3 m Signup and view all the answers

What is the charge weight per hole in the example calculation for open pit mine bench blasting?

159.65 kg Signup and view all the answers

What is the rock volume per blast hole in the example calculation for open pit mine bench blasting?

327.6 m3 Signup and view all the answers

What is the charge diameter in the example calculation for open pit mine bench blasting?

152.4 mm Signup and view all the answers

What is the explosive density in the example calculation for open pit mine bench blasting?

0.85 gm/cm3 Signup and view all the answers

What is the bench height in the example calculation for open pit mine bench blasting?

14 m Signup and view all the answers

What is the subdrill length in the example calculation for open pit mine bench blasting?

1 m Signup and view all the answers

What is the burden in the example calculation for open pit mine bench blasting?

4.5 m Signup and view all the answers

What is the spacing in the example calculation for open pit mine bench blasting?

5.2 m Signup and view all the answers

Study Notes

Blasting Techniques and Factors

Detonation sequences include rows shooting parallel to the highwall, a "V" pattern, or chevron for different blast patterns
Preparations for blasting involve cleaning holes with compressed air, charging them with explosives, and checking circuit resistance for electric detonators
A detonator is a small device triggering a larger explosive, while initiation systems provide the initial energy for detonation
Selection of explosives considers economic, performance, and safety factors, as well as rock strength and field conditions
Powder factor, a key parameter for bench blasting, indicates the relationship between rock breakage and explosive usage
Powder factor value ranges from 0.1 to 0.7 kg/m3 for normal bench blasting, affected by rock blastability, fragmentation, explosive performance, and charge distribution
The formula for powder factor (q) is q= We Vr or q= We Wr, where We is the weight of explosive charged, Vr is the volume of rock to be blasted, and Wr is the weight of rock to be blasted
Calculating the powder factor involves determining loading density, charge length, charge weight per hole, and rock volume per blast hole
An example calculation for open pit mine bench blasting includes determining loading density, charge length, charge weight per hole, and rock volume per blast hole
An example calculation yields a loading density of 15.5 kg/m, charge length of 10.3 m, charge weight per hole of 159.65 kg, and rock volume per blast hole of 327.6 m3
The powder factor for the example is 0.49 kg/m3, calculated using the formula q= We Vr
The example involves a charge diameter of 152.4 mm, explosive density of 0.85 gm/cm3, bench height of 14 m, subdrill length of 1 m, burden of 4.5 m, spacing of 5.2 m, and no inert deck.

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Description

Test your knowledge of blasting techniques and factors with this quiz. Explore detonation sequences, preparations for blasting, selection of explosives, and the calculation of powder factor. Gain insight into key parameters for bench blasting and understand how to apply formulas to real-world examples.

Blasting Techniques and Factors Quiz

Podcast Beta

Questions and Answers

What type of blast pattern has drilled spacings larger than drilled burdens?

What dictates the movement and fragmentation of a shot in millisecond delay blasting?

What is the typical range of gas pressure created by a blast that moves the rock out from the blast face?

What effect does an increase in the number of rows have on the movement of rock in a blast?

What is the formula for Powder Factor?

What is the loading density for a charge diameter of 152.4 mm?

What is the formula for the loading density interpolation?

What is the range for small diameter blasthole drilling diameter?

What are the three main factors that influence rock breakage?

What does the formula $f(x) = -4(x + 3)^2 + 2$ represent?

What is the formula for the length of bottom charge in large diameter blasthole?

What influences the selection of explosives according to the text?

What is the formula for powder factor (q)?

What does the powder factor value range from for normal bench blasting?

What is the loading density in the example calculation for open pit mine bench blasting?

What is the charge length in the example calculation for open pit mine bench blasting?

What is the charge weight per hole in the example calculation for open pit mine bench blasting?

What is the rock volume per blast hole in the example calculation for open pit mine bench blasting?

What is the charge diameter in the example calculation for open pit mine bench blasting?

What is the explosive density in the example calculation for open pit mine bench blasting?

What is the bench height in the example calculation for open pit mine bench blasting?

What is the subdrill length in the example calculation for open pit mine bench blasting?

What is the burden in the example calculation for open pit mine bench blasting?

What is the spacing in the example calculation for open pit mine bench blasting?

Study Notes

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