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Vibrations are of concern not only for the safety of surface structures but also for the stability of underground openings. A number of parameters affect the intensity of vibration in underground openings due to blasting in adjacent opencast mine viz. total explosive weight detonated in a round, maximum explosive weight per delay, propagating media, depth of cover, RMR of the roof rock, age of the underground openings etc. Although a few researchers have tried to study the impact of parameters stated above, the impact of initiation sequences on generation of vibration in underground openings due to opencast blasting has yet remained untouched. A study was planned to evaluate the impact of initiation sequences on the magnitude of vibration in underground openings due to blasting in opencast mine. Nine production blasts with top and bottom initiations were performed at Samleshwari opencast project in India and eighteen vibration data were monitored in the roof of Hingir Rampur underground colliery in both the initiation sequences. The result indicated that the vibration produced in the underground openings from bottom initiation was lower than that of top initiation.

Jan 1, 2003

By David Siskind, Mark Stagg

Vibrations from Dade County (Miami area) quarry blasting and structure responses were measured at 11 locations between February and April, 2000, and 10 homes were inspected to analyze the characteristics of their cracking and other damages. These results were combined with information collected by the County and other studies done in south Florida for a blasting impact assessment specific to this area. In addition over 40 quarry blasts in the nine-week monitoring period, about 800 measurements were available from previous monitoring in Dade and neighboring Broward counties. An overall worst-case analyses based on the highest individual amplitudes suggested that vibrations in some areas could have been as high as 0.35 in/s. While amplitudes in the study period were below this value, they were found to be relatively high for the distances and charge sizes. Attenuation with distance is less in Dade County than found elsewhere with quarries having to use scaled distances several times higher than similar sites in the north. Consequently, the vibrations are perceptible at very large distances.

Jan 1, 2001

By Hung Tran, Qian Liu, Patrick Andrieux, Dave Counter

Blast damage in open stope mining has been an important concern in controlling ore dilution. Severe damage to the surrounding rock mass can result in the caving of waste rock and/or backfill materials, as well as general instability of the ground. The blast damage study conducted at Kidd Mining Division in 1995 was aimed at measuring the damage zone around blastholes and at identifying other factors which influence the damage. An approach and methodology developed mainly by Blastronics, together with Noranda under a project with the Mining Research Directorate, was adopted for this project. The principle was to combine vibration measurement results with borehole camera observations to derive the blast damage criteria at the specific site. The Holmberg-Persson Equation was used for the regression of near-field vibration data. The damage criteria was examined with both borehole camera observation results and rock elastic and mechanical properties. Details of this methodology, including instrumentation, are reviewed in this paper and an implementation case study of the blast damage evaluation is presented.

Jan 1, 1998

By Changa-Ha Ryu, Hae-Moon Choi, Sang-Don Lee

The rock mass to be excavated is classified using data obtained from the initial site investigation, and the design of excavation and support is then made based on the rock class. Rock classification provides an empirical design with guidelines for tunnel support compatible with rock mass quality and the method of excavation. Although most clients provide standard patterns corresponding to each rock class, the patterns of drilling and blasting have only been used in estimating the excavation cost and not used in the construction stage. The purpose of the study presented in this paper is to establish a standard blast pattern to yield optimum blasting performance along with an attempt to reduce a difference between design and construction. A series of test blasts were carried out at two tunneling sites of Central Inland Highway crossing the country. Long hole blasting was tested in rock mass whose RMR value is over 60. The blasting results were evaluated by measuring degree of fragmentation, advance rate, muckpile distribution, overbreak, etc. Based on the results of test blast, several patterns were proposed for a twolane highway tunnel.

Jan 1, 2005

Bloomfield Collieries Rix’s Creek Mine is an open cut coal operation located in the Hunter Valley region of Australia. The mine produces approximately 1.1 mt of saleable product per year and routinely employs cast-blasting practices for its unique dragline-truck overburden excavation method.

Jan 1, 2006

By Minoru Kawamura, Koichi Kurokawa, Yukio Kato, Kenji Hashimoto

It is well known that ground vibration by blasting is mainly related to a distance and charge weight. However, it is not known the correlation between ground vibration and performances of explosives; for example, shock wave energy, bubble energy, detonation velocity and ballistic mortar value etc..

Jan 1, 1991

By Judy Konya Bowles, Calvin J. Konya

Blast vibration and air blast are commonly blamed for damages to residential as well as commercial structures. Mining and construction companies are often required to spend monies in court defending themselves even when vibration and air blast levels have been monitored by seismographs and are extremely low.

Jan 1, 1992

By Franklin J. A, Tam C. Palangio, N H. Maerz

WipFrag systems I, II and III have become the world standard in photoanalysis systems to measure particle sizes. Mines, quarries and excavating contractors can now easily measure blast results and track the progress of optimization efforts. This technology was developed and evolved ~to allow automatic measurements of the size distribution of particles on moving conveyors, in truck boxesand on crusher feeds. Production machinery can now be controlled by photoanalysis results and multiple cameras allow various locations to be monitored by a single system. Blast designs can, be monitored on a shot by shot basis. Changes in delay times, explosives, patterns and hole sizes can be quickly evaluated. Along with this measurement capability has come a heightened awareness of the importance of “optimum size” and uniformity of particles for lowest cost production and material handling efficiency. In the past, savings in the “drill / blast” cycle of the operation were sometimes overshadowed by downstream production costs related to fragmentation. Now total production costs can be compared with fragmentation sizes, which will immediately show the trend towards optimum size for economical production. No cost reduction program can be complete without this critical information.

Jan 1, 1998

By Benjamin Cebrian

Metallurgical testing at Cobre Las Cruces prior to production at the mill was done with overburden gossan. Some of that test gossan was a very fine material, wet by the water conditions at the bottom of the pit. When processed and stored wet at the fines material 3000 tonne (3307 tons) silo, this material cemented in a very unusual manner.

Jan 1, 2010

By William F. Skully

An effective explosives storage program involves selection of a storage site, checking zoning and special permit requirements, acquisition of the storage site land, determining correct layout for required storage units, selection of storage units, construction of storage area, obtaining licenses and permits, and storage site operation.

Jan 1, 1976

By N H. Maerz

The digital image analysis program WipFrag has been developed under contract to INCO for use in quality control of underground blasting operations. This paper outlines the relevance of fragmentation to underground mining, the hardware and photography requirements, and key features and operating principles of the software.

Jan 1, 1995

By D K. Joyce

Large diameter boreholes have become increasingly popular in underground mining. Drilling equipment can drill full rings, including vertical upholes. Special techniques are required to load upholes of three inch to eight inch diameter. The current methods for loading AN/FO and bulk or packaged emulsions are described.

Jan 1, 1988

By Jeff Gore, Jack Dermody, David Gribble, Brett Macaulay, Bart Sharpe, Paul Klaric, Paul Thornley, Ben DeVries

Optimal Fragmentation in Block Caving is difficult to achieve as it is generally defined by the rock mass itself and the way in which the cave is initiated. The lower portion of the cave has even less chance as the material has little time for self comminution. Blast Preconditioning of the Block Cave is designed to engineer the lower section of the rock mass to produce material of a suitable size to assist in the initial cave propagation and improve initial drawbell productivity. At Cadia East a plan was developed to drill 150-metre long, vertical up-holes from the undercut level and blast them fully confined to produce fractures in the rock mass. The blast itself was a simple undertaking. However, in the year preceding the first production blast, all aspects of the process were designed, tested and refined across multiple trials. As this type of challenging application had not previously been encountered in Australia there were many unique situations to address. Products and systems had to be developed and adapted to overcome these challenges. These included: Formulating and manufacturing an explosive that is robust and of a high VoD; designing and manufacturing easy to use electronic initiation systems; and, designing pumping systems to combat high head pressures to allow for successful and safe loading of the holes. Close collaboration with the customer ensured that the trials culminated in successfully blasting a hole containing almost 3.3t of explosive. These trials have since led to the blasting of four holes instantaneously, which contain almost 13t of explosive. This paper describes the various components of the system, the challenges and the final result.

Jan 1, 2013

By Sharon K. Reamer, Yvan Sifre, Klaus-Gunter Hinzen

"Three case studies are presented that illustrate the successful application of firing timeoptimization (hybrid modeling) in the quarry environment and for a construction site. In allcases, the method requires the measurement of at least one in situ, single hole explosion asa representative model of the desired blast design."

Jan 1, 1993

By Norman Paley, Zachary Pickett

The Red Dog Mine is a high-grade zinc-lead mine located in northwest Alaska which began operations in November 1989. In June 2014 the upper half of a charge in a trim shot in the Aqqaluk pit deflagrated. No other holes in the area were observed to react and the remainder of the pattern was shot without incident. This was the only known case of a deflagration in the 25 years of operations. As part of the investigation into the cause of this incident rock samples were obtained from the area of this hole and from other areas in this pit. The samples were assayed and tested for reactivity using the Reactive Ground Catalyzed Adiabatic test. Approximately half of the samples were found to be reactive with standard blasting agents. Unexpectedly, some of these were found to be reactive with blasting agents doped with urea to act as an inhibiter. Relationships between element grades and reactivity and between Specific Heating Capacity and reactivity were developed; however, the small sample size led to these models having an unrealistically large number of geological model blocks tagged as reactive. A program to better understand the behavior by testing more samples was initiated. Drill core was selected based on the predicted level of reactivity using the aforementioned relationships. The samples covered a greater range of grades and lithologies and included rock from the soon to be developed Qanaiyaq pit. The samples were dry pulverized then split for elemental assay, Reactive Ground Catalyzed Adiabatic testing, Specific Heating Capacity (SHC) determination, and X-ray Diffraction (XRD) mineralogical analysis. From this data, a Red Dog Mine specific assay based classification for separating reactive from non-reactive ground was developed. Furthermore, it was possible to divide the reactive ground into two subgroups: i) rock which reacts with ANFO-emulsion blends even when manufactured specifically with a reactivity suppression agent like urea and ii) rock which reacts with ordinary ANFO-emulsion blends only when a reactivity suppression agent like urea is absent.

By S. P. Singh, Turgut Yalcin

The physical characteristics of blasted rock are fundamental variables affecting the economics of mining operations and are in fact the basis for evaluating the quality of a blast. A study was designed with the objective of quantifying the effect of muck size distribution on scooping operations in a mine.

Jan 1, 2002

By Matthew Baumann, Bahram Sameti, Tafazoli Zeng Hairong, Edmond Chow

An automated, centralized, image-based rock fragmentation analysis system provides blast engineers with the benefit of minimizing tedious and mundane work, and allows them to focus on their expertise of blast optimization. In typical manually-operated image-based rock fragmentation analysis, much time is spent on collecting proper images, handling and transferring data, and processing for fragmentation.

Jan 1, 2013

By Winfried Rosenstock

Following successful trials at Chuquicamata / Chile from February to May 2000 and from February 2001 onwards at Burton Coal Mine, RAG International/Thiess Pty Ltd., Queensland / Australia a significant advancement in blasting technology was achieved using electronic detonators. The mine now uses electronic intiation for the majority of overburden blasting.

Jan 1, 2002

By Carl Hendricks

AQUILA Mining Systems Ltd. is the world leader in drill monitoring, control and GPS based drill navigation systems for the mining industry. This paper will review the general design and application of AQUILA.s drill systems currently in use throughout the world and the key benefits that derive through their use.

Jan 1, 2002

By N. Paley

An engineering project was undertaken at the Cominco Alaska Red Dog Mine to determine the extent that Semi-Autogenous Grinding (SAG) mill throughput could be increased by blasting differently. The Julius Kruttschnitt Mineral Research Center (JKMRC) blast fragmentation, jaw crusher, and SAG mill breakage models were used to relate changes in the blast design to the SAG mill performance. For optimum performance a SAG mill requires a particular size distribution; a number of large rocks to facilitate breakage by impact, as few as possible middle size rocks that become critical size, and the maximum fines which will pass quickly through an open-circuit mill. Physical constraints of drill and charging equipment size limit the extent that pattern geometry can be changed and the powder factor increased to maximize fines. However, JKMRC research had shown that it appeared possible to increase primary breakage by blasting to such an extent that SAG mill throughput could reach a plateau or even begin to decrease. Modeling was carried out on a range of blast pattern geometries and emulsion explosive blends to determine if a plateau existed and at what powder factor it would be reached. It was found that the relationship between powder factor and grinding throughput was nonlinear. Modeling was also used to compare the SAG mill throughput which could be expected from different emulsion explosive blends to determine which blends should be used in dry and wet holes to provide similar fragmentation. For heavy-ANFO mixtures, the highest modeled throughput was at a ratio of 30/70, with ratios on either side indicating lower throughput. For emulsion blends, the highest modeled throughput was at a ratio of 80/20; however, ratios from 80/20 to lOO/O were similar. Crusher product size distributions were obtained from belt cuts early in the analysis to confirm model predictions. At later stages, actual SAG mill throughput was compared to predicted. The economic benetit from the different blast designs was calculated by accounting for the reduction in recovery due to the higher throughput and the additional drilling and blasting costs. Increasing the powder factor by 150% from the 0.29kg/t {0.58lb/st] being used to 0.72kg/t { 1.44lb/st}, the maximum feasible with mine equipment, could provide a sign&ant net benefit of $3OWyr due to the increased concentrate production. However, because the relationship between throughput and recovery is affected by other factors which were not modeled, a more conservative approach was taken. The powder factor was instead increased by 50°h, providing 45% of the gain. This was possible because the relationship between powder factor and grinding throughput was nonlinear.

Jan 1, 2001