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By D Anonby

The Fox Pit at EKATI Diamond Mine is designed with 11 m wide benches excavated using a double benching technique leaving 30 m high faces. Blasting tests were conducted to increase the percentage of benches that meet an 11 m catch width. The subdrill depth for the lower bench trim blasts and the blasthole diameter for the upper bench trim blasts were reduced to maintain the bench crests. Raising the lower trim blastholes by 0.5 m decreases the depth of broken rock below the final bench elevation, and consequently reduces damage to rock that forms the bench crest below. The use of smaller diameter (165 mm vs. 270 mm) blastholes in the A and B rows for the upper trim blast reduces the charge per delay during detonation, reduces the powder factor slightly, and reduces the energy affecting the final pit wall and crest.

Jan 1, 2007

By Robert Jacob Cefalo, Rio Tinto Kennecott

At the end of 2016, the Mine started a new ore phase in the section of the pit located on the East Wall. The East Wall geological structures required controlled blasting for peak particle velocity (PPV) frequency vibrations to protect the wall. Frequency controlled blasting using linear seed wave superposition modeling was required and implemented to reduce the far-field affects to the wall. This paper covers the work done by the drill and blast engineering group, controls used to protect the mine infrastructure, and the continuation of work-to-date of frequency controlled blasting for wall stability. The narrow width of the layback required the combination of hole sizes to blast large diameter production patterns with smaller diameter trim patterns in the same blast. A single blast had to use different burden & spacing and hole diameters and required the use of different timings throughout the pattern. Electronic detonators were required to limit blast vibrations and accommodate the specific timings needed to reduce low frequencies. The geotechnical group with the help of geotechnical radars worked with the drill and blast group on creating a tracking and reporting of blast performance. The radar readings informed the drill and blast engineers of the performance of the blast as it related to the long term performance of the highwall

Jan 1, 2019

By Mark S. Stagg, Siskind David E

The mining industry occasionally blasts near pressurized transmission pipelines and has requested guidance on safe vibration levels and setback distances. The Bureau of Mines and the Indiana Department of Natural Resources cooperated with AMAX Coal Company on a study of coal mine overburden blasting. Five buried and pressurized 250-ft pipeline sections were specifically installed on the Minnehaha Mine highwall near Sullivan, IN for testing to failure. Four welded steel pipes ranging from 6- to 20-in diameter and one 8-in PVC water supply pipe were monitored for vibration, strain, and internal pressure for a period of 6 months while production blasting advanced up to the pipeline field. In contrast to previous studies of small-scale blasting representing construction activities, these tests involved overburden blasts of up to 2100 lb per delay in 12-1/4-in diameter holes.

Jan 1, 1993

By Jennifer P. Harrell, D. Joseph Hagerty

In many areas of the eastern United States, especially in the Midwest, past mining activities have left large and extensive underground openings. Now, renewed mining is occurring in such areas in surface pits. Also, construction blasting often occurs in rock over such old openings. Within the last fifteen years, some attention has been given to the interaction between surface blasting and underground cavities; concern has been expressed about the possible changes in vibrations transmitted through areas underlain by old mine workings (Siskind, Stachura and Nutting 1987). Previous studies also had indicated that underground openings could influence transmission of surface mine blast vibrations (see, for example, Woodward-Clyde Consultants 1977). The principal concern is that underground openings under surface blasting may intensify low-frequency vibrations. If such intensification occurs, use of available equations to predict peak particle velocities and to design blasting patterns and select blasting parameters could lead to possibly damaging ground shaking.

Jan 1, 2002

By U Nyberg

Peak particle velocity (PPV) and distance measurements from a single-charge blast test conducted by Swedish researchers in iron ore at the Kiruna Mine in northern Sweden are presented. They are used along with theoretical PPVs calculated using an equation based on hydrodynamics to determine a damage distance range caused by a single charge. This equation, which relates PPV to explosive properties, charge geometry, and distance from a charge, was then applied to a charge of different geometry that was used in drift rounds. A comparison between calculated and measured PPVs suggests that the stoping holes likely damage the easer hole locations, and the easer holes produce damage to the perimeter hole locations. The practical effect is that typical damage limit predictions based on measurements conducted in fresh or undamaged rock are conservative. This suggests that even when perimeter control is not exercised in drifting (i.e., the perimeter holes are fully loaded), the resulting damage may be less than normally expected due to the wave damping effect of the pre-damaged rock. Due to the damping effect, poor perimeter blasting practices are somewhat self correcting. However, it must be strongly emphasized that well-engineered blast designs with perimeter control are highly beneficial in relation to both economic and safety aspects.

Jan 1, 2011

By Piyush Rai

Proper use of fi ring pattern vis-à-vis the blast requirements can provide optimal blast performance in terms of fragmentation. Further to this, each fi ring pattern has its own characteristic, for instance, although V-type and diagonal fi ring pattern provide same Se/Be ratio, the V-type fi ring pattern increases the opportunity for in-fl ight collision amongst broken rock fragments during their movement. Similarly straight V-type and skewed V type fi ring patterns (V1,V2 etc.) have their own characteristic strengths and weaknesses. In this light the present paper highlights the application of three different types of fi ring pattern on two different type of sandstone overburden benches of a large coalmine in India. The study reveals that Firing pattern infl uences the effective spacing to burden ratio at the time of detonation. By changing the fi ring pattern, effective burden (Be) changes and the ratio of effective spacing (Se) to effective burden (Be) during the fi ring is also subject to change in comparison to drilled spacing to burden ratio (S/B) Hence, the Se/Be ratio vis-à-vis fi ring pattern must be used to design the blast rounds. The results have been derived on the digital image analysis based fragment size characterization, excavator performance and evaluation of powder factor values on blasted muck piles. Skewed V- type fi ring yielded the best results in comparison to straight v-type and normally practiced diagonal fi ring pattern on the moderately strong sandstone benches, whereas, the existing diagonal fi ring pattern appears to be satisfactory on weak (weathered and gritty) sandstone benches. The presence of geological anomalies has also been investigated.

Jan 1, 2008

By Visitor Makiyi, Chris Batten

Poor coal recovery due to coal damage or loss caused by blasting can have a significant impact on a mining operation. Increasing coal recovery by reducing blast damage can provide a significant opportunity for coal mines to maximise their revenue and reduce their operating costs. This paper provides details on advanced drilling and blasting techniques used throughout the coal industry globally to prevent coal damage and movement during blasting. Typical coal loss and damage mechanisms are explained, along with how each of the applied techniques works to minimise the impact of each mechanism. Key requirements for a coal loss reduction program are detailed with typical design parameters used for each of the methods discussed. The positives and negatives of each method are also provided to enable comparisons and help determine suitability for a particular coal mining operation.

Jan 21, 2025

By Sanjay Sengar, Nabiullah Pingua, Saurabh Sahay

In India, more than 80 percent of the total of 557 million metric ton coal production comes from open-cast mines involving large overburden removal with average 1:3.5 stripping ratio which is going to in-crease in future. This operation consumes nearly 0.5 million metric ton explosives consisting of 80-85 percent bulk explosives and remaining 15 to 20 percent non-permitted large diameter explosives. Quali-ties of bulk explosives play an important role in rock blasting. Post blast results like poor fragmentation, tight mucking, toe problems, improper muck profile and lower productivity of mine may require chang-es in explosive loading factor (amount of explosive used per unit of rock blasted ). The explosive load-ing factor is an extremely important index to assess the economy of blasting operation.

Jan 1, 2014

By Trevor Ames

Highwall instability, and sometimes referred to as ground failures, historically are a consistent contributor of mine injuries and fatalities within surface mines. To combat this several efforts, including those from NIOSH (CDC), to educate the mining community with insightful literature focused on hazard recognition and advances in ground monitoring systems have been performed. The question is can more be done or is this our last line of defense to manage potential dangers? Is there a more effective method to reduce hazards presented by ground failures including rockfalls?

Jan 1, 2015

By John T. Aler

The U.S. Bureau of Mines has been studying the problem of why explosives detonate weakly or misfire during blasting in underground coal mines. Cross-borehole shock wave interaction has been identified as a predominant mechanism causing explosives to function improperly (1)(Underline numbers in parenthesis refer to items in the list of references at the end of this report.). Cross-borehole shock wave interaction can be simulated in a laboratory setting, making possible the replication of tests in sufficient numbers to understand and quantify some of its effects on permissible explosives (2). The work presented here investigates the capacity of explosives to partially recover from the desensitizing influence of the shock wave. The recovery trend of different explosives can indicate optimum blasting patterns useful for minimizing borehole charge malfunctions.

Jan 1, 1991

By Doug Anderson

Two quantities, Peak Particle Velocity (PPV) and Scaled Distance (SD), have controlled aspects of many blasting projects and operations for a long time. Vibration criteria typically use both PPV and SD because they are simple to measure, and simple to calculate. Their use in regulations worldwide is fairly ubiquitous, in efforts to limit damage to structures in the neighborhood of a blasting operation. PPV and SD are also used to determine likely blast damage effects in mining operations.

Jan 1, 2018

By Virgil J. Stachura, Larry R. Fletcher

The Bureau of Mines conducted a series of delayed blasting experiments at a West Virginia contour coal mine which resulted in smoother highwalls. The highwalls were smoother due to reduced overbreak and inherently safer due to reduced likelihood of rockfall. Reduced overbreak was accomplished by an increase in the highwall hole delay intervals which changed the effective delay pattern geometry and the direction of burden movement. Three combinations of blast delay intervals in the highwall holes were tested: 1) 50 ms longer than the nominal design, 2) 50- and 100-ms longer delays in the nearest two rows that form the highwall, and 3) 100 ms longer than the nominal design. The mine's nominal blast design was a flat vee formed by 17-ms surface delays between holes and 42-ms surface delays between rows, with 200-ms in-the-hole delays. All three test designs produced highwall improvements over the nominal design with only occasional exceptions because of geologic variations.

Jan 1, 1985

By R R. Singh, U K. Dey, S K. Roy

"Commercial explosives being a heterogeneous mixture of many chemical compounds in prefixed proportion, their velocity of detonation (VOD) may vary from batch to batch, due to variations in the proportion of the chemical composition and process parameters even within their tolerance limits. Inherent limitations of measuring methods and human variations during measurement also add to the variation in VOD values determined practically. Therefore, it is customary to define a range of VOD values rather than a fixed value of VOD for a particular explosive.Variations in VOD values of four commercial permitted explosives in India were evaluated under open unconfined condition using Dautriche method and a resistance wire method based continuous VOD meter. Comparative evaluation of VOD values of selected explosives were aimed to check the relative effectiveness of continuous VOD measurement of small diameter cartridged permitted explosives using cheaper co-axial wire instead of recommended costly VOD rods along with the continuous VOD meter. Results of evaluation revealed that continuous VOD of commercial small diameter cartridged explosives could be determined using cheaper co-axial resistance cable with comparatively better accuracy than the most commonly used Dautriche method."

Jan 1, 2007

By Richard Mainiero, James H. Rowland III

For many years there have been small scale tests available for evaluating the toxic fumes production by capsensitive explosives (DOT Class 1. l), but these could not be used with blasting agents due to the large charge sizes and heavy confinement required for proper detonation. Considering the extensive use of blasting agents in construction and mining, there is a need to determine the quantities of toxic ti,tmes generated by blasting agents. At the International Society of Explosive Engineers Twenty Third Annual Conference on Explosives and Blasting Technique in 1997, the authors reported on a facility for detonating large (4.54 kg), confined blasting agent charges in a controlled volume that had been constructed at the National Institute for Occupational Safety and Health’s Pittsburgh Research Lab’s Experimental Mine. Since 1997, this facility has been used to collect data on toxic fumes produced by the detonation of various ammonium nitrate/fuel oil (ANFO) mixtures and several cap-sensitive explosives. ANFO composition ranging from 1 to 10 percent (pet) tieI oil have been studied. As expected from previous studies, with an increase in fuel oil content the carbon monoxide production increases, while nitric oxide and nitrogen dioxide production decrease. The detonation velocity varies from 3,000 to 4,000 m/set for the 1 to 10 pet range of fuel oil content, suggesting that ANFO mixes with improper fuel oil content may appear to detonate properly, while their fume production differs significantly from optimum. The study also considers such factors as degree of confinement, water contamination, and aluminum content on blasting agent fume production. Results indicate that water contamination of the ANFO has little effect on carbon monoxide production, but causes significant increase in nitric oxide and nitrogen dioxide production. Decreasing confinement from Schedule 80 steel pipe to 0.4~mm thick sheet metal also has little effect on carbon monoxide production, but significantly increases nitric oxide and nitrogen dioxide production. Adding 5 and 10 pet aluminum to the ANFO had no clear effect on carbon monoxide, nitric oxide, or nitrogen dioxide production.

Jan 1, 2000

By Mike Higgins

"The purpose of mining and its related industries is the removal of, and usually the subsequentprocessing of, material from the earth. This includes mining for minerals, quarrying for stone, and civilexcavations. Where this involves rock, the most common method is to fragment the rock by blasting. "

Jan 1, 1997

By David Nemir, Jan Beck

A challenge in materials science is the production of a bulk solid material from a powder precursor. One solution is to use shockwave consolidation whereby a ductile tube is loaded with the powder of interest and then surrounded by an explosive. A detonator at the top of the explosive column initiates a symmetrical high-pressure pulse that moves inward and down the tube, causing the tube to deform and the interior powders to consolidate into a dense, well bonded bulk material.

Jan 1, 2016

By W. Reisz

The fear of heights is a natural defense against performing a dangerous and unnatural act such as standing on the edge of a hundred foot wall. Yet through familiarity, a casual attitude often exists. Those of us, who work near highwalls on a daily basis, may become overly comfortable in our surroundings, losing sight of the disaster which may often rest a single misstep away. And this is where the hidden dangers lie.

Jan 1, 2009

By R Holmberg, C Sjoberg, B Larsson

This paper describes the excavation of an underground naphta storage facility at Stenungsund in Sweden. The main purpose with this paper is to give an overall view of how the excavation was carried out and in what type of bedrock the storage was built. Emphasis has been done to highlight the importance of using cautious blasting to avoid blast damage in the remaining rock. Attempts has also been done in order to evaluate what the degree of Swedish cautious blasting has meant for the rock support costs during the construction period.

Jan 1, 1984

By Isaac E. "Chip" Harris

Any contractor who agrees to supply materials or to perform services for a sum, is well aware of the importance of proper pre-bid information. Being able to properly plan costs and methods results in profits that allow the contractor to prosper. The paper discusses procedures used in estimating pre-bid cost; in particular, drilling and blasting cost for highways, dams and general construction projects. It breaks cost down into five categories and relates them to a total estimate used in bidding and budgeting a construction project.

Jan 1, 1975

By Brian Wingfield, Rick Givens, Greg Williams

Many technological advancements have been made in explosive products and applications over the last 15 years resulting in productivity and cost gains. However, the application of total energy (engine horsepower) in the majority of rotary drilling technology, has remained virtually unchanged over that period. While advancements have been made in components, efficiency, and types of hydraulic systems used on drills, the application of current hydraulic technology to improve drilling productivity has not been interactive with end users.

Jan 1, 1996