secondary blasting of rocks

    secondary blasting, Irrespective of the method of primary blasting employed, it may be necessary to reblast a proportion of the rock on the quarry floor so as to reduce it to a size suitable for handling by the excavators and crushers available 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 ,H BLASTING IN SURFACE EXCAVATION, rock pile with a possible secondary fragmentation due to impacts between rocks projected from opposite directions , However, secondary blasting is the most expensive type of blasting Appropriate blast design is important in order to lessen the production of over size(PDF) ROCK BLASTING FOR MINING, 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, 2017 ,BEST PRACTICES IN DRILL AND BLAST, amounts of oversize rock which cannot pass through the crusher and will require size reduction before being taken to the crusher Conducting fragment break-up is costly and needs secondary blasting or use of a mechanical hammer for rock disintegration UNIQUE FACTORS THAT INFLUENCE FRAGMENTATIONCost of Blasting, Oct 15, 2003· Rock blasting can cost anywhere from $300/m³ to $150/m³ depending on location in the world and location relative to buildings, etc Small diamter drills (115mm and less) cost about $20,000 USD/month to operate So figure $1000/day if you drill and $1500/day if someone else drills.

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    5 Rock Excavation Tools | Drilling and Excavation ,, Thermal spalling drills such as jet-piercing and forced-flame drills heat rocks to 370 to 540°C (700 to 1000°F) to create thermal stresses that spall the rock ()These devices have limited application because most rocks will not thermally spall (Maurer, 1968, 1980) Melting and vaporization drills utilize high-temperature devices such as lasers or electron beams to melt and vaporize rock ()Engineering Geology Field Manual, rocks similar to the typical rocks listed in table 19-1 Denser rocks such as basalt require smaller ratios (higher powder factors) Lighter materials such as some sandstone or bituminous coal can be blasted with higher ratios (lower powder factors) The hardness or brittleness of rock can have a significant effect on blasting resultsRock Boulder Blasting with Explosive, Table of ContentsBlockholingSnakeholing or BombingMudcappingBlasting Mats Boulders can be broken up using either explosives or mechanical methods which can be implemented in many ways Handling boulders hung up in crushers is inherently inefficient for the overall operation, and the techniques in handling them each have their own advantages and disadvantag Table 4 shows a comparison of ,Construction Blasting Risk Management | Expert Commentary ,, At blast time, the Blaster-in-Charge should fire or instruct the designated shot-firer to fire the blast After the post-blast fumes have dissipated to safe levels, the Blaster-in-Charge should inspect the shot area During the examination the blaster should look for: Dangerous rock conditionsSecondary blasting | Article about secondary blasting by ,, In secondary blasting, explosive denotation release a huge amount of energy which results to rock shattering and scattering and consequently high fly rocks Comparative analysis of hydraulic drop ball and secondary blasting technique for secondary breaking in aggregate quarri.

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    Surface Mine Blasting, rock fragmentation, blasting effects on Appalachian water wells, blast vibration measurement near structures, and the reduction of accidents through improved blasting safety 2 BUREAU OF MINES SURFACE MINE BLASTING RESEARCH By Dennis V D'Andrea1 ABSTRACT The Bureau of Mines Twin Cities Re­ ,Effect of the Location of the Detonation Initiation Point ,, Jern [] studied the relationship between the acoustic velocity of damaged rock masses and the distance to the blast hole, based on the field experiment in Angered MineFrom the measured velocity near the hole and far from the hole, the parameter was 47% and the damage variable was 072 Gorbunov [] probed into the effect of blasting on rocks based on the acoustic investigation at Inguri StationDrilling and Blasting | Technical Aspects of Mining ,, Blasting in a mine generally occurs in two phases, primary blasting and secondary blasting Blasting Primary Blasting is the activity in which in-situ rock is broken in both development and stoping and in surface mining by drilling holes in the rock, charging them with explosives and detonating the holes in a planned sequenceA study in cost analysis of aggregate production as ,, Oct 01, 2017· Blasting is one of the most important operations, and has substantial technical and economic effect on the mining projects In such projects the prime aim of blasting operations is rock fragmentation that is necessary for subsequent processes (such as transportation, crushing, etc) to achieve a higher efficiency (Monjezi et al, 2013)Detonator, A blasting cap is a small sensitive primary explosive device generally used to detonate a larger, more powerful and less sensitive secondary explosive such as TNT, dynamite, or plastic explosive Blasting caps come in a variety of types, including non-electric caps, electric caps, and fuse caps.

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    SGB for the Mining and Minerals Sector SKILLS PROGRAMME ,, Skills Programme Description: Secondary Blasting Operations for Underground Hard Rock 2 3 Registration Number: 4 Total Credit Value: Minimum of 36 5 Band on the NQF FET 6 Field: Manufacturing Engineering and Technology Sub-Field: Fabrication and Extraction 7 Issue Date: 8 Review Date: 9 Purpose of Skills ProgrammeDESIGN OF SURFACE BLASTS, 8 variation of avg production with diameter and rock type 43 9 Relationship of bench height, stemming with diameter & UCS of rock for large blast hole 44 10 Relationship of sub drilling with blast hole diameter for large blast hole 44 11 List of burden and spacing values for various compressive rock strengths and explosiv 45How to Blast, or Break Rock With Blasting Powder, Gun Powder, Oct 15, 2020· A good blast will just crack the rock Too much charge or placing the hole too near a rock face will result in 'air burst', where rock flies into the air This is dangerous and wasteful Too little charge, or placing the hole too far away from a rock face will result in almost no rock breakage This method works well when you can drill a hole ,(PDF) Rock breaking methods to replace blasting, Nov 10, 2020· General mechanical rock break ing rock blasting method is small, high safety, suitable for part of a rock breaking and secondary rock br eaking, especially for rock breaking requirem ents of ,Comparison of Blast, Sep 14, 2013· This paper focuses on the comparison of damage induced by smooth blasting and presplit blasting based on the excavation of high rock slope The whole damage process of the smooth blasting and presplit blasting excavation method is studied by using a cumulative blasting damage numerical simulation technology based on the secondary development of the dynamic finite element ,.

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    (PPT) MINIMIZATION OF BOULDERS DURING BLASTING AT ,, DELAY TIME Due to hardness of rock at Nyanza Road Quarry, it has been observed that the blasting parameters applied were not suitable for improved fragmentation The calculated Burden, spacing and stemming height should be used instead of the current parameters for proper fragmentation Sub-drill and bench height should be kept constant for all ,Taking precautions against flyrock | Business Queensland, avoiding overcharging when conducting secondary blasting Previous excavations and the driller of the blast holes can provide important information about the rock's structure The area surrounding a blast site must be inspected to determine the distances to residences, roads, ,