What are the factors affecting blasting?
What are the factors affecting blasting?
The major factors affecting the blast-casting results include: bench height, burden, dip angle of blast holes, powder factor, delay time interval, presplitting blasting effect, blasting patterns, and so on.
What is delay in blasting?
The practice of initiating individual explosive decks, boreholes, or rows of boreholes at predetermined time intervals using delay detonators, as compared to instantaneous blasting where all holes are fired essentially simultaneously.
What are blasting parameters?
The parameters to be considered for blast casting are the overburden rock characteristics, blast geometry, spacing to burden ratio, delay interval, stemming and decking, Page 16 8 bench height to width ratio, explosive used etc.
What is the process of blasting?
Blasting, process of reducing a solid body, such as rock, to fragments by using an explosive. Conventional blasting operations include (1) drilling holes, (2) placing a charge and detonator in each hole, (3) detonating the charge, and (4) clearing away the broken material.
What is charge factor in blasting?
blast design, blasting, surface mining. 1 INTRODUCTION. The specific charge (powder factor) is a measure of the mass of an explosive required. to break a unit volume or a unit mass of the rock.
What are the precautions to be taken in the process of blasting?
Precautions to take
- selecting the direction of the blasting face to place people and buildings behind the face.
- avoiding shallow blasts less than 1m in depth, and using high blast ratio and small hole diameters where possible.
- ensuring burden is one-third to one-half the depth of holes.
What is delay detonator?
An electric or nonelectric detonator used to introduce a predetermined time lapse between the application of a firing signal and detonation.
What are the types of blasting?
Sand Blasting. Image Source: ABITL Gallery.
What is spacing in blasting?
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. Chapter 8. BLAST DESIGN.
How many types of blasting are there?
There are various types of abrasive blasting including, silicon dioxide, soda, steel, bristle, glass bead and much more. All these different abrasive blasting methods usually use a specific type of grit to achieve the desired results, hence the need to determine the correct technique to use.
How drilling and blasting is done?
Drill and Blast Method
- Drilling blast holes and loading them with explosives.
- Detonating the blast, followed by ventilation to remove blast fumes.
- Removal of the blasted rock (mucking).
- Scaling crown and walls to remove loosened pieces of rock.
- Installing initial ground support.
Why is blasting important in the m Ining cycle?
So, Blasting is an essential aspect in the m ining cycle. Now, blasting has become a technology by itself. Many Mega engineering projects need some kind of blasting of basement rocks. explosive so that a predetermined volum e of material is broken down into pieces.
How does blasting affect the ground around the blast site?
Ground vibrations propagate away from a blast site as Rayleigh (or surface) waves. These waves form a disturbance in the ground that displaces particles of soil or rock as they pass by. Particle motions are quite complicated.
What are blast design considerations in open pit mining?
Not only do these provide evidence of the quality of his work, but they also provide a wealth of information upon which he can draw as future blasting situations develop. Blast Design: This is meant to be a toolbox for blast design in conventional rock quarrying and open pit mines.
What is the purpose of air decking in blasting?
Air decking is a widely used controlled blasting technique that requires an air space in the blast hole above the explosive charge [5]. The purpose of this air space, called a deck or air-deck, is to allow for the gases generated during the detonation process to fill the void instead of being forced into the adjacent rock mass [5].
Ground vibrations propagate away from a blast site as Rayleigh (or surface) waves. These waves form a disturbance in the ground that displaces particles of soil or rock as they pass by. Particle motions are quite complicated.
How is the productivity rate of rock blasting determined?
In most cases, the productivity rate is influenced by the degree of fragmentation. To obtain well-fragmented rock by blasting, explosive energy must be well distributed throughout the rock. To be effective in rock blasting, this energy must be applied at the proper millisecond delay interval to allow for optimum rock movement.
Not only do these provide evidence of the quality of his work, but they also provide a wealth of information upon which he can draw as future blasting situations develop. Blast Design: This is meant to be a toolbox for blast design in conventional rock quarrying and open pit mines.
Which is the most important dimension in blasting?
The most critical and important dimension in blasting is that of the burden. The choice in burden will ultimately affect the entire performance of the blast. This is due to the fact that the burden dimension is the first step to designing the proper confinement for a blast. Should the burden be too large, the explosive will never break the rock.
