Secondary Blasting: Secondary blasting is carried out in two ways: 1. Pop Shooting: A hole is drilled by jackhammer for charging with explosive and blasting the boulder. Normally a depth of 0.3 to 0.6 m is sufficient for most of the boulder sizes. The explosive, widely used, is special gelatine in conjunction with safety fuse or detonators. 2.
After a production blast, a secondary blast may be required to reblast a portion of the rock to reduce it to a size fit for handling by the machines and equipment available (Balasubramanian,...
Secondary stress state of the tunnel under in-situ stress. Under smooth blasting conditions of the deep tunnel, peripheral blastholes are detonated after blasting of other blastholes on the tunnelling face. The static stress distribution on rocks around peripheral blastholes is displayed in Fig. 13. The formation of coalesced fractures between ...
Primary blasting involves breaking down of in-situ rock in development and stopping as well as by drilling holes in rocks. Secondary blasting is performed to get rid of overburden. Drill and blast ...
or eliminates the amount of secondary blasting while minimizing wear ... When rocks are extremely well jointed blasting ratios as high as 15 tons per lb of explosive may be obtained. The volume of rock on each of a row of shotholes is approximately a prism, with dimensions equal to the burden, the spacing and the depth of ...
Secondary blasting or some form of impact breaking are often required to reduce oversized rock fragments after primary blasting. The 'rippability' of a rock body, as an alternative to blasting, depends upon strength, fracture spacing and other factors, which can be assessed by geophysical or geotechnical techniques. 31, 32
Blasting in a mine generally occurs in two phases, primary blasting and secondary blasting. Primary blasting involves breaking down of in-situ rock in development and stoping as well as by drilling holes in rocks. Secondary blasting is performed to get rid of overburden. Drill and blast design is a key component of mine planning and management.
Blast rounds for the same design (blast 1-1 and blast 1-2), blast 2-1 and 2-2, and blast 3-1 and blast 3-2 gave different results, indicating the effect of rock intrinsic properties.
Two methods of secondary blasting of rock are available. The first, called the plaster or mudcap method, is to fire a charge of explosive placed on the rock and covered with clay, the shock of …
Several products have come on the market in recent years that improve the safety of secondary blasting operations. The most significant of these are binary 911 Metallurgist is a trusted resource for practical insights, solutions, and support in mineral processing engineering, helping industry professionals succeed with proven expertise. | Rock ...
As described in "Rock Fracturing Mechanism by Blasting" [2], the detonation products generated within the reaction zone create a cylindrical pressure wave that propagates through the rock medium ...
This unit describes the skills and knowledge required to conduct secondary blasting in the coal and metalliferous mining and extractive sectors. It includes pre-blasting and post-blasting activities to support blasts. It applies to those working in operational roles. …
1.1 ROCK FRAGMENTATION IN MINING 1 1.2 OBJECTIVES AND OUTLINE OF THIS STUDY 3 CHAPTER 2 THE CONCEPT OF OPTIMUM BLASTING 5 2.1 CHOICE AND QUANTITY OFEXPLOSIVES 6 2.2 SECONDARY BREAKAGE PROCESSES 9 2.2.1 Secondary Blasting i) Pop Shooting ii) Plaster Shooting 10 iii) Snakeholing 14 iv) Shaped Charge Shooting
In rock blasting for mining production, stress waves play a major role in rock fracturing, along with explosive gases. Better energy distribution improves fragmentation and safety, …
This book enriches the readers with the advances in rock blasting techniques for mining and civil construction rock excavation projects, including the need for and importance of rock blasting, related theories, challenges in rock blasting operations, and rock blasting methodology for excavation of coal and overburden benches of opencast coal mines. It also discusses methods …
This book enriches the readers with the advances in rock blasting techniques for mining and civil construction rock excavation projects, including the need ... Discusses methodologies of secondary blasting. This book is aimed at graduate students and researchers in mining, geotechnical, and rock engineering. 130.0 In Stock 5 1.
Primary blasting involves breaking down of in-situ rock in development and stoping as well as by drilling holes in rocks. Secondary blasting is performed to get rid of overburden. How is blasting powder factor calculated? Powder factor can be expressed as a quantity of rock broken by a unit weight of explosives. Or, alternatively, it can be the ...
2. Trim Blasting—A controlled blasting method that cleanly shears a rock face when there is insufficient burden for production blasting. It is essentially identical to presplit blasting, but without production blast holes. (b) Production Blasting. Rock fragmentation blasting that typically has more widely spaced blastholes than
Secondary Blasting -in open cast mines during the blasting in the high benches are broken. Many times the required fragmentation is not formed and large lumps are created. …
The drilling-blasting method 1,2 can harm the surrounding rock, compromising the stability of the rock mass 3,4.Techniques like smooth-surface charge blasting and directional blasting can mitigate ...
Blast-induced rock fragmentation is the result of the combined action of blasting stress waves and explosion gasses. The decoupling charges affect the rock-breaking abilities of the …
1 INTRODUCTION. The drilling-blasting method 1, 2 can cause damage to the surrounding rock, affecting the stability of the overall rock mass. 3, 4 Smooth-surface charge …
Blasting in a mine generally occurs in two phases, primary blasting and secondary blasting. Primary blasting involves breaking down of in-situ rock in development and stoping as well as by drilling holes in rocks. Secondary blasting is performed to get rid of overburden. Drill and blast design is a key component of mine planning and management.
productivity, secondary blasting/breaking costs and secondary blasting damage (Laubscher, 1994). ... BCF was developed to estimate primary and secondary fragmentation from rock fabric data. Rock fabric data, consisting of joint spacing, orientation, and length, can be collected by scan-line or cell mapping ...
After the blasting excavation, as shown in Fig. 5b, d, f, if the free face before blasting excavation is taken as the benchmark to calculate the damage depth of the surrounding rocks, the ...
Low-density rocks require a less explosive charge to break a unit volume of the rock whereas very dense rocks require a higher amount of specific explosive charge to detonate [35]. p q = 0.27 3 f k g/m3 Where f is rock sturdiness index.
Though rock blasting is a commercially viable venture, it is advised to be careful at the planning stage in order to produce a blast design that will ensure optimum blast result. The design should be made to enhance proper utilization of blasting energy in the rock fragmentation. ... Secondary blasting could either be plaster (mud-cap) blasting ...
These examples and many others emphasize the important role of rock fragmentation in blast design. Until recent years, when blasting was more of an art than science, most of the above …
(7) Which of the following refer to the type of blasting where damage to the remaining or surrounding rocks is minimized. a. all of these b. line blasting c. smooth blasting d. perimeter blasting e. cushion blasting