Questions and Answers
What is the defining characteristic of a rectangular blast pattern?
What is the purpose of a staggered blast pattern?
What is the typical timing for rock fragmentation after detonation?
How does the movement of rock change as the number of rows in a blast increases?
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What is the formula for powder factor (kg/m3)?
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What is the loading density for a charge diameter of 152.4 mm?
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What is the equation to calculate the loading density for different charge diameters?
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What is the range for small diameter blasthole drilling?
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What are the three main factors that influence rock breakage according to the text?
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What is the main property of explosives that influences the explosives selection?
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What is the equation to calculate the length of bottom charge for large diameter blasthole?
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What are the key steps of the rock fragmentation process by blasting according to the text?
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What is the formula for powder factor (q)?
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What does the powder factor value range from for normal bench blasting?
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What is the purpose of a detonator in blasting?
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What factors are considered in the selection of explosives for blasting?
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What does the powder factor indicate?
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What are the preparations for blasting?
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What is the role of initiation systems in blasting?
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What does the formula $q = We/Vr$ represent?
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What is the key parameter for bench blasting?
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What is the purpose of cleaning holes with compressed air before blasting?
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What is the range of the powder factor value for normal bench blasting?
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What is the weight of rock to be blasted represented by in the formula $q = We/Vr$?
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What is the primary goal of blasting according to the text?
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What is the purpose of maintaining a stable highwall in a blasting operation?
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What does the term 'burden' refer to in bench blasting?
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What does the term 'spacing' represent in bench blasting?
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What is the function of stemming in bench blasting?
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What is the purpose of sub-drilling in bench blasting?
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What are the main factors that influence rock breakage according to the text?
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What is the potential consequence of close hole spacings in bench blasting?
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What material can be used as stemming in bench blasting?
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What is the distance drilled below the floor level in sub-drilling used for?
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What is the potential consequence of wide hole spacing in bench blasting?
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What is the role of spacing in row-to-row shooting in bench blasting?
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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.