Search Documents

By Armin Iravani, Changping Yi, Matthias Wimmer, Daniel Johansson, Santiago Gómez, Håkan Schunnesson

Sublevel caving (SLC) is a mass mining method based upon the utilization of gravity flow of blasted ore and caved waste rock. Drilling and blasting are the initial and the major impact on primary fragmentation and later material flow characteristics. The heterogeneity of rock mass has a great impact on materials’ mechanical properties and plays a significant role in rock fragmentation by blasting. In this work, a numerical model for sublevel caving based on 3D Voronoi tessellations was developed to section rock mass into arbitrarily shaped regions for modelling the heterogeneous rock mass. A coupled finite element and discrete element method was employed to investigate both the fragmentation due to blasting and the gravity flow of ore in a heterogeneous orebody. In the coupled model, the caved waste rock was modelled with loose discrete particles while the orebody to be blasted was simulated with bonded particles. The detonation of explosives was described with a particle blast method and a finite element model was used to model the remaining orebody. The results indicated that the fragmentation at the upper part of the ring is coarse while it is fine at the lower part of the ring. The heterogeneity of rock mass induced some boulders after blasting.

Feb 6, 2023

By Dale Preece, Vanessa Berg

This paper presents a two-pronged vulnerability analysis approach for treating minimally reinforced concrete (RC) structures subjected to explosive events. This work was motivated by a heightened interest in homeland protection involving both malevolent and accidental explosions and the need for assessment of critical facilities subjected to an explosive detonation. The first part of the analysis approach employs the commercial 3-D Eulerian-Lagrangian hydro-code AUTODYN, while the second part of the analysis employs Single-Degree-of-Freedom (SDOF) methods, each predicting the dynamic response of the minimally RC walls, slabs and columns to explosive loading. The concrete is treated with the newly developed RHT (Riedel, Hiermaier, Thoma) constitutive model, which accounts for failure mechanisms in brittle materials. Predictions from AUTODYN are verified using the equivalent SDOF reinforced concrete code, SPAn32, developed by the US Army Corp of Engineers and agreement between the results indicates a high level of accuracy in both methods of analysis, allowing for accurate predications of airblast-structure interactions and failure mechanisms.

Jan 1, 2004

By Thad M. Jones

This paper considers the sampling, digitizing and reconstruction of seismic signals. A sampling frequency range is proposed and a minimum limit is suggested. Digitizing precision criteria for both peak velocity and analysis applications are given. Several methods for reconstructing signals from sampled data are presented.

Jan 1, 1985

By Theodore C. Hile, Floyd P. Henry, Ken Gragg

"Conventional explosive-storage methods usually rely on combinations of earth and concrete barriers, along with sufficient distance between limited explosive loads, to avoid accidental conflagration. However, under many circumstances, Air National Guard (ANG) facilities co-located with civilian airfields have trouble meeting necessary Quantity-Distance (Q-D) requirements for Explosive Hazard Class/Division 1.1 and 1.4 materials. Because of the danger posed by explosives stored in earthcovered magazines (ECMs) too close to civilian activities, ANG units often find itdifftcult to maintain adequate stores of ordnance needed to meet unit mission goals."

Jan 1, 1999

By Michael Weaver, Dale L. Ramsey

The Pinkerton Tunnel open cut project is part of the National Gateway Clearance Initiative improvement project to achieve a minimum of 21 feet of vertical clearance along CSX Transportation rail corridor so that double-stacked intermodal railcars can be transported between mid-Atlantic states and their ports to midwest markets in the U.S. This project involved drilling and blasting of 1.2 million bank cubic yards of rock over a 14 month period while maintaining rail traffic of two passenger and 38 freight trains daily. See story and photos, page 6.

Jan 1, 2015

By Michael J. Sapko, Eric S. Weiss

The U.S. Bureau of Mines has been conducting research on the secondary explosion hazards associated with the mining of oil shale under gassy mine conditions. Explosive incendivity tests have been conducted in a 28 m~3 (1000 ft~3) gallery to evaluate the relative incendivity of experimental emulsion-ANFO blends. The incendivity was measured by determining the minimum inert stemming requirements for preventing the ignition of a methane-air atmosphere by the discharge of hot detonation products from a 5.7 cm (2.25 in) diameter borehole.

Jan 1, 1990

By Mark S. Stagg, Rolfe E. Otterness, Farrokh Djahanguiri

The U.S. Bureau of Mines (USBM) evaluated empirical equations that predict fragmentation from underground stope rounds. Controlled blasting is necessary for creating leaching stopes that maximize the recovery and minimize backbreak of the perimeter wall. This paper presents the fragmentation results from one of the three drop-raise blasts used to develop a reduced-scale cylindrical stope, 1.8 m in diameter and 6 m in height. The stope is located in the Colorado School of Mines Experimental Mine (Edgar Mine) in Idaho Springs, Colorado. This stope is part of a USBM research effort to determine the feasibility of incorporating in situ leaching of rubblized stopes into active underground metal and nonmetal mines.

Jan 1, 1994

By L. Chaves

In rock blasting, due to numerous factors, both controllable and uncontrollable, the execution rarely meets the planning. The powder factor is an important KPI for blasting since it represents the amount of explosive used to fragment the rock, therefore it depends on the rock mass characteristics and may be influenced by factors such as weathering and drilling quality. The blasts at the Serra Sul mine, S11D project, are usually big blasts and the high productivity is a challenge for maintaining the quality of the whole drill and blast process. It is important to know the contributions of each of the most common influencing factors of the powder factor to direct the efforts to the improvement of the process. A buildup model is presented to evaluate the contributions of five influencing factors to evaluate the planed x executed powder factor. The factors considered in the model are the average hole depth, the amount of hole/blasted volume, the stemming and decking length, the linear charge weight, and the density of the explosive used. The build-up may be applied for both individual blasts and for overall view of the blasts in a period. A case study is presented with the application of the model for the monthly powder factor analysis at Serra Sul mine has contributed to direct efforts to enhance drilling quality and preservation of the drilled holes.

Jan 1, 2024

By Cathy Aimone-Martin, Kristin Dunlap Kolden

Blasting was conducted for the Army Corps of Engineers (Corps) in the Columbia River near Saint Helens, Oregon during 2009 and 2010 to deepen the navigation channel as a final phase of a dredging project to accommodate larger container ships. The Columbia River Channel Improvement Project (CRCI) required 4 months to blast and dredge 300,000 yd3 (229,366 m3) of basalt from the bottom of the channel to allow Post-Panamax vessels with drafts up to 50 ft (15.2 m) access to the Ports along the River. Explosives charges were limited to 90 lbs (40.8 kg) per delay for the protection of fish and marine life in the area. A fish mortality study and marine mammal monitoring program was also required by the Corps. Underwater overpressure monitoring was required for each blast and peak overpressures measured 10 ft (3.1 m) above the river bottom 140 ft (42.7 m) from the closest blast hole were not to exceed 70 psi (483 kPa) with a cautionary level of 40 psi (276 kPa). Specifications required sampling rates of 500k S/s and PCB Peizotronics tourmaline pressure sensors. The Corps granted permission to co-locate additional ceramic-type sensors at different sampling rates to design redundant monitoring systems 140 and 300 ft (42.7 and 91.4 m) from blasting and develop a site-specific overpressure attenuation model for the project. This paper presents the correlations of overpressure with cube-root scaled distance factors, a comparison of measurements using three different pressure sensor systems, and a discussion of blast design influence on overpressure measurements.

Jan 1, 2014

By Zhang Yangde

"This paper reports the clinical research work of Micro-explosion of Biliary Calculi . In theprogram the technique of directional micro explosion applied to disintegrate the biliarycalculi of body and decreases the rate of operation. Up to the present, 235 cases of biliaryduct calculi have been successfully treated by use of implusive force of micro-explosion .The success rate of blasting stones was 100% by the use of the directionalmicro-explosive instrument made by us , the once success ratio of micro-explosion was93.2% and tl~o rmulb of treatment were satisfactory. . Considering the density of theblood vesselsiD the human liver, limitation of space in the h~patic.ducb, the securiey andadaptation, we have designed two types of micro- explosives equipment called ZS device,electric initiation and nonelectric initiation to initiate explosion. The head diameter of thedevice ie 1.5-1.8 mm . It is applicable to all kinds of fiber endoscope by inserting ZSdevice under grossing eyes or TV set ."

Jan 1, 1993

By Lindsay Wade, Peter Dare-Bryan

Benches in surface mines often contain known areas of ore and known areas of waste, which must be mined selectively. When rock is blasted it not only fragments but is also physically, and non-uniformly, moved. Risks therefore exist of ore being lost if treated as waste and of mill feed being diluted by waste. Both possibilities carry serious fmancial implications.

Jan 1, 2001

By Jorge Cárdenas, Diego Gamarra

In previous phases of the mine, a landslide resulted in several losses in production delays. The stability of slopes in a mining operation is critical for the sustainability of the operation, as they are exposed to vibrations and damage caused by blasting. Therefore, it is essential to implement controls and innovative technologies to reduce these vibrations levels. This study focuses on the application of low-energy emulsions with lower densities than conventional explosives, developed to reduce vibrations and the energy delivered to the rock mass adjacent to the near blast holes as a buffer row. Near field studies were carried out by embedding triaxial geophones. Vibrations were recorded, and mathematical models of vibration associated with different types of explosive mixtures were generated. This allowed us to determine the benefit of implementing low-density explosives in reducing vibrations compared to Heavy ANFO explosives. The application of low-energy explosives with densities ranging from 0.7 to 0.8 g/cm³ and Relative Bulk Strength (RBS) of 51-65 allows for a 40% reduction in vibrations compared to the detonation of Heavy ANFO explosives.

Jan 21, 2025

By Joe Atalla, Jesse Desrochers, Rodrigo Hayashida, Joseph Mukendi Kabuya

The Mont-Wright mine stands as a prominent open-pit operation in Canada, renowned for its vast iron-ore reserves. However, the efficacy of its blasting operations, crucial for efficient production, has encountered challenges due to the diverse lithological compositions across multiple pits. This study presents a comprehensive approach to optimize blasting practices at Mont-Wright mine, tailored to the specific lithological characteristics of each rock domain. Through systematic analysis and experimentation, blasting guidelines were meticulously developed, aiming to enhance grindability and equipment productivity. The implementation of these guidelines promises significant improvements in operational efficiency and resource utilization, positioning Mont-Wright mine at the forefront of sustainable iron-ore extraction.

Jan 21, 2025

By Quian Liu

Since the establishment of the CANMET Experimental Mine in Val d'Or, Quebec in 1991, research activities in rock fragmentation have been carried out not only in the underground laboratory but also in production mines in the north-west Quebec region. Among the instruments available for rock fragmentation, the Kodak EktaPro 1000 Motion Analyzer (also called the high speed video system) has been one of the most useful tools for monitoring blasts in both underground and open pit. This system is capable of recording events at rates from 50 to 12,000 frames per second (fps). The buffer memory has a capacity of storing 2050 images. To use this system in the underground, a steel box was made with a bullet-proof glass in the front to protect the camera. The processing and recording equipment are placed in an aluminum case which can be located about 30 m away from the camera via an extension cable. For each blast monitored, high frequency geophones and accelerometers were used to monitor ground vibrations and give a timing reference of the explosive detonations to correlate with the observation of the captured images.

Jan 1, 1994

By Hapsari Rosa, Ross Cowie

Conventional blasting activities in the mining process use various types of explosives, with the primary raw materials being Ammonium Nitrate and diesel fuel. The quality and specifications of the two raw materials significantly affect the performance of explosives. One program from the Indonesian Ministry of Energy and Mineral Resources requires mixing 30% Bio Diesel 30 with 70% diesel fuel oil in several industrial sectors, including mining, to reduce greenhouse gas emissions and stabilize CPO prices. This program aims very well for environmental sustainability and the palm oil business. However, it turns out that this change impacts the performance and results of the blasting process in the mining industry, which is the appearance of fumes. This paper will discuss the tests carried out in the laboratory on Bio Diesel 30, the explosive products used, and rock samples were taken from a mine in East Java, Indonesia. The aim is to determine what factors can cause fumes utilizing a mixture of Bio Diesel 30 with pure diesel fuel. The parameters tested were visual differences, infrared spectrometry, density and viscosity, surface tension and contact angle for Bio Diesel 30, stability test for explosives, and the SEM-EDS method for rock samples.

Feb 6, 2023

By Virgil J. Stachura, Larry R. Fletcher, Paul V. Sterk, Matthew N. Plis

The large diameter blastholes now being used in underground mining have caused concern because of their increased potential for damaging openings and creating rockfall hazards. In response to this situation, the Bureau of Mines is conducting research to reduce the amount of overbreak and damage to the perimeter of underground openings. This paper presents the results of tests with decoupled charges in 6.5 inch diameter blastholes, and unloaded guide holes, in Vertical Crater Retreat (VCR) stope panels at the Homestake underground gold mine in Lead, SD.

Jan 1, 1991

By Dyno Nobel

Impact of Enhanced Security on Operations Budgeting - What is the “value” I receive for enhanced security? Is there a “return” for the money I spend? Regulatory driven Economic driven

Jan 1, 2006

By Norman Paley

A blasting project was undertaken at the Teck Alaska Red Dog Mine to determine the extent that Semi-Autogenous Grinding (SAG) mill throughput could be increased by using electronic detonators. The Julius Kruttschnitt Mineral Research Centre (JKMRC) blast fragmentation, jaw crusher, and SAG mill breakage models were used to relate changes in the blast fragmentation measured with the SPLIT image analysis system 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, a growing number of studies have shown that the use of electronic detonators can lead to increased fragmentation and greater muckpile uniformity, providing an alternate means of increasing primary breakage by blasting. Unfortunately results in the literature rarely quantified the changes to the fragmentation distribution. The measured gyratory crusher fragmentation of 2,750,000t of ore was used to compare stockpiles constructed from shots using pyrotechnic detonators to those using Orica i-kon electronic detonators. In the first stage of the study, stockpiles shot using 25 ms inter-hole timing with pyrotechnic detonators were compared to stockpiles shot using the same inter-hole timing with electronic detonators. In the second stage of the study, stockpiles shot using 17 ms inter-hole timing with pyrotechnic detonators were compared to stockpiles shot using 8 ms inter-hole timing with electronic detonators. When electronic detonators were used with the inter-hole timing kept constant, fragmentation uniformity was slightly increased, but mean fragment size increased by 20%. When electronic detonators were used with faster inter-hole timing, fragmentation uniformity was slightly reduced, but mean fragment size decreased by 30%. Modeling was used to determine the SAG mill throughput which could be expected from this change in fragmentation to determine the pairs of pyrotechnic and electronic blast pattern geometries that would provide similar throughput. The economic benefit from the electronic detonator shots was calculated to assist in determining the optimum blast designs for their use.

Jan 1, 2010

By Joel Chipana, Roberto Laredo, Benjamin Cebrian

Ring blasting is a common production method in underground metal mines. As a drill and blast process, it presents particular features that do not correspond with bench blasting in open pit or underground mining.

Jan 1, 2017

By Jerry Newton

The bulk explosives industry is relatively young compared to how long explosives have been in use. It's been around for about forty years, about the length of a person's career. This period of explosives history has seen constant change. The type of product, the manufacture and the trucks that haul it have changed a great deal over the years.

Jan 1, 1997