The volume of material to be blasted is calculated by the rock-volume formula, as follows: Volume = burden dimension x spacing dimension x (hole depth – subdrill length)/27, where • hole depth – subdrill length = bench height∗ and • burden dimension, spacing dimension, and bench height all are measured in feet.
How do you calculate burden spacing?
- Spacing = Hole diameter x 12.
- Burden = 0.5 x production blast burden (B)
- Uncharged length at top = 10 x D.
- Powder factor = 0.5kg per square metre of face.
- Do not stem holes. Fire all holes on the same delay, or in groups of ≥ 5 holes.
How much power does a blasting cap have?
Blasting Caps are designed to have a minimum firing current of 0.25 amps.
What is the formula of blast ability?
Most of these studies have suggested that the parameter that best correlates with both the energy developed from the explosion and the stress suffered by the rock-mass and nearby structures is the vibration velocity or, more precisely, the peak particle velocity ppv, expressed according to the following equation:(1) …
What is maximum charge weight per delay?
The maximum quantity of explosive charge detonated on one interval (delay) within a blast. The charge detonated within any 8-ms interval over the entire duration of the blast.
What is burden and spacing?
The term SPACING denotes the lateral distance on centers between holes in a row. The BURDEN is the distance from a single row to the face of the excavation, or between rows in the usual case where rows are fired in sequence.
How much does it cost to blast rock?
Depending on the type of rock, the size of the job, placement, contractor rates, the equipment being used, and geographical location, most rock excavation jobs will cost $5 to $35 per cubic yard if a blasting method is used, but this price could be much higher if it were a public bid job.
How fast is a blasting cap?
Exploding bridgewire detonator or blasting cap Both Match and Solid Pack type electric caps take a few milliseconds to fire, as the bridgewire heats up and heats the explosive to the point of detonation. Explosive bridgewire or EBW detonators use a higher voltage electric charge and a very thin bridgewire, .
What is blast pattern?
The array of drilled holes on the surface or underground to be loaded and detonated in sequence; a pattern is indicated by the distance between holes in a row (spacing) and between rows (burden).
How to bid on an abrasive blasting project and profit?
All things being equal, a deep anchor pattern requires a faster-moving particle, requiring more air pressure and the right abrasive (ie. garnet instead of crushed glass). Nature of the coating/contaminant. How thick is the corrosion to be removed? How durable is the coating? Removing light scale will go quicker than blasting barnacles.
What’s the difference between sandblasting and bead blasting?
Sandblasting or bead blasting is a generic term for the process of smoothing, shaping and cleaning a hard surface by forcing solid particles across that surface at high speeds; the effect is similar to that of using sandpaper, but provides a more even finish with no problems at corners or crannies.
Can a flat surface be used as a blasting surface?
Unless you’re blasting a big, flat surface, your effective production rate is going to be lower than your ideal production rate. A dissimilar surface with lots of different angles and shapes, or in hard to reach places, can take many times longer.
How can abrasive blast cleaning improve blast efficiency?
The results clearly indicated that the newly optimized blasting condition can improve blasting effi- ciency and significantly reduce the amount of abrasive used. The study also showed a general trend—that blast- ing productivity is gradually increased with the abrasive feeding rate to a certain critical value and then maintained constantly.
