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By Mike Wheat, Catherine Aimone-Martin, Brandon Pease

The Kneeling Nun rock pinnacle is a prominent landmark, 90 ft in height and 35 ft in width, that resides on a bluff overlooking the Santa Rita pit at the Chino Mines Co. operations near Silver City, New Mexico. The company plans to expand the current pit limits, resulting in a change in direction and distance of hard rock mine blasting operations in relation to the pinnacle. Concerns about the stability of the pinnacle adjacent to mining activity has prompted company personnel to enhance the seismic monitoring program both on the pinnacle and along the current open pit highwall that forms the base support below the pinnacle foundation. This paper presents the vibration response characteristics of the pinnacle, in terms of amplitude and natural frequencies of motions and damping characteristics, for measurements recorded at the top and base of the pinnacle. The influence that blasthole initiation timing and sequence of hole detonations have on vibration response is discussed. A simple analysis is made to estimate factors of safety against cracking of the landmark as well as blast-induced slope instabilities within the foundation rock.

Jan 1, 2000

By Charles O'Connor, Ben Tisa

International Training Resources is a company consisting of personnel with extensive law enforcement and military special operations experience, The staff members are qualified to train and certify, assist and advise law enforcement officers and agencies, at any level, in critical incident policy, procedures and tactical resolutions. Successful critical incident resolution is comprised of many elements of professional skills and personnel. (Command staff, negotiators, snipers, tactical teams, uniform patrol, K-9, bomb squad, etc.) Recently, tactical teams have been developing the capability for the use of explosive methods for rapid entry into crisis locations. This document ‘will briefly describe the environment, operational issues and courses of action associated with developing a complete tactical breaching program for utilization by SWAT teams in response to operational conditions in critical incident situations. This topic is being presented to the I.S.E.E. evaluators under “Interesting Blasting Projects” and “Public Relations” categories. Tactical operations differ significantly from traditional industry practices and we appreciate the opportunity to show the industry other professional applications of explosive materials and techniques. Presently, of the few schools from which law enforcement officers can receive training with explosive breaching methods, International Training Resources is the only company currently teaching and certifying officers which has received total endorsement by the California Peace Officer’s Standards and Training Commission (P.O.S.T.) and the state blaster’s licensing commission. We have pioneered the combining of law enforcement needs and blasting industry technology to train tactical officers, nationwide, in the mission essential skills necessary for explosive breaching.

Jan 1, 2000

While ring-blasting techniques offer substantial benefits, there are intrinsic problems that are exacerbated when large blocks of ore are mined in attempts to improve the production economics. These problems relate to both the convergence of holes around the ring drive and the charging of up-holes. The size and shape of the ore block concerned should be carefully considered so that good drilling, patterns can be achieved. The hole diameters chosen, both affect and are affected by the size of the ore block. The explosive selected depends on the hole diameter and together with the diameter, determines the nominal drilling pattern. Ring-drilling patterns are best derived through the use of computer software together with engineering judgement. The loading of explosive is necessarily high, and charging patterns require careful thought if overcharging is to he minimised and adequate energy is to be available at all parts of the ore block. Initiation systems are critical to the blasting results, but sub-optimal systems must be adopted if collar priming is practised. In view of all these factors, idealised guidelines can be given for ring design, but it should be recognised that developments in technology may in time change some of these parameters.

Jan 1, 2000

By Xue Yongpeng, Zhu Zhenhai, Zhu Ming

The purpose of the Solid Medium Controlled Blasting Technique and Its Applications is to have the inside of the vessel-shaped framework (e.g: oil tank , water pool, gas chamber, chimney, water tower, grain warehouse and etc.) or the one side of the thin wall-shaped structure(e.g: steel bar concrete wall and etc.), both of which are intended to be demolished, inserted with the required solid medium (e.g: soil , sand , coal, salt and etc.) ,in which there is a certain mass density, and then through which the blasting energy is transferred to fulfill the blasting task. For such a technique, it is necessary to bury the explosives into the inserted solid medium and then to start the explosion to blast the intended target into pieces. The filling of the solid medium may be done mechanically or by man. Compared with the water pressure blasting technique, this one has the characteristics of good effect. wide application, simplified construction procedure , safe and reliable operation and small vibration (less vibration than water pressure blasting by 80% to 90%)in particular without any flying stones, thus resulting in better and comprehensive social and economickfficiency.

Jan 1, 2000

By Dale Preece, Stephen Chung

The DMC-BLAST (Distinct Motion Code) has been developed for modeling bench blasting to one or two free faces such as choked blasting in surface gold operation and cast blasting in coal mining, respectively. This computer code has been used to assist the analysis of rock mass displacement after a blast was initiated in an orderly delay sequence. Applications of this feature can be found in the studies of dilution control in surface mining of gold as well as coal involving complex rock structures. Recently, DMC-BLAST has been modified to include a designated delay firing order coupled with variable rock strengths in the blasted media. This newly added feature allows the investigation of the effects of delay firing order on rock displacement in blasting a complex interbedded ore-waste structure. Examples of blasting a steeply dipping coal seams and bedded rock structure, especially in coal mining operations will be addressed and the comparison of efficiency in blasting in an up-dip as opposed to blasting in a down-dip direction will be discussed. Also covered in the paper is a new application of DMC-Blast to simulate a stope blasting underground. Simulations of blasting in a few selected types of timing/structure combinations will be presented in this paper.

Jan 1, 2000

By Hung Tran, Denis Fleury, (Ken) Qian Liu

Pastefill technology has gained an increasing popularity over the past decade. The main advantages are: environmental performance (mainly in tailings disposal), low operation costs and ease of operation, as well as homogeneous properties. However, its weaker nature compared to other types of fill makes it more vulnerable to blast damage. In the last few years, Louvicourt Mine has experienced some cases of pastefill sloughage during the mining of secondary stopes. In order to reduce pastefill sloughage, some studies have been undertaken to investigate the causes and to find possible solutions by looking at stope design, extraction sequence, ground support and blast design. This paper presents the results of a blast damage study carried out at Louvicourt on the 860m level. The instrumentation included vibration monitors (using 6 sets of triaxial geophones grouted in the pastefill), a borehole camera to observe the damage in the pastefill, and a cavity monitoring system for three-dimensional surveys of the blasted stope. The test stope was mined out by four slot blasts and three mass blasts. Most of the damage was created by the mass blasts. It was found that the accumulation of ground vibration was mainly due to the low seismic velocities in the pastefill and the relatively tight delay between blastholes. In addition, there was a substantial difference between the critical PPV in the confined and unconfined pastefill. In practice, these findings have led to modifications of blast design to minimise the exposure time of pastefill walls to air. Such modifications included changes of blast sequence in secondary stopes and delay layout between heavily loaded blastholes. Over the paste two years, the implementation of new blast sequence has shown encouraging results in terms of reduced pastefill sloughage and dilution.

Jan 1, 2000

By Douglas Rudenko

Have you ever had a neighbor complain about a blast one day, but says the next day’s blast was better, even though the Peak Particle Velocity (PPV) increased? How about neighbors that complain about a small trimming shot, but don’t complain about a big production shot? Have you ever reduced the pounds/delay and gotten more complaints ? Mine operators are often bewildered when trying to correlate blast design parameters to homeowner complaints. When complaints come, standard practice is to set up a seismograph in the neighbor’s yard to monitor the blast. Immediately after the blast, the neighbor usually reappears from the house wanting to know the seismograph reading. When told that the PPV was 0.1 in/set, well below damage levels, the homeowner explodes saying “Your machine is wrong”. Perhaps he is right. Understanding why people complain about blasting is not about PPV, it’s all about structural response. People could care less about how much the ground vibrates; they only care about how much their house vibrates. In this paper we will examine the primary factors that control structural response. Through the use of a large array of digital seismographs, the effects of two production blasts on a community surrounding a quarry are studied. The predicted structural response resulting from each blast is calculated at 175 seismograph locations. The predicted response is then correlated to previous research on human perceptibility to vibrations. The results of this analysis and correlation give a better understanding of what the residents actually feel in their homes. The detonations of two single-hole signature blasts are also recorded by the array of seismographs revealing the dynamic characteristics of the geology ‘surrounding the quarry. Once the influence of the geology was understood, blasts were configured to disrupt the natural rhythm of the site through the use of millisecond delays.

Jan 1, 2000

By John Vynne

Too often, a mine’s operations, including drilling, blasting, loading, hauling, crushing, processing, etc., are considered independent steps, rather then a continuous process. In fact, these are interdependent operations with each step in the process having an impact on subsequent operations. If the effectiveness of the drilling and blasting operations can be improved, they will impact the entire mining process. Some of the resulting improvements include: level benches on grade; fragmentation and diggability with the result being reduced loading times; haul cycles improvements; and the crushing and milling operations will be more efficient and less energy consumed. Thunderbird refers to this as “Drill to Mill” information cycle or process. This paper focuses on two of the technological enhancements Thunderbird has added to its drill monitors that allow the mines to impact the “Drill to Mill” concept. These enhancements are: incorporating global positioning satellites into drill monitors; and radio off-loading of data. Thunderbird is part of the Integrated Mining Systems (IMS) alliance. IMS offers the mining industry the most comprehensive line of monitoring and navigation products available today for mobile mine equipment. In addition to Thunderbird’s drill monitors and GPS systems, the product line includes: Fleet Management Systems for trucks and loaders; dragline and shovel monitors; GPS based navigation systems for shovels, dozers and other mobile equipment; and surveying systems. IMS uses common communication systems, operating systems, and hardware components in order to provide a truly Integrated Mining System.

Jan 1, 2000

By D. Scott Scovira, Remi Proulx

The Meikle Mine is a high grade, underground gold mine utilizing primary-secondary longhole open stoping with delayed backfill to produce 3000 stpd of ore. Hot and reactive ground conditions were encountered early on in the mine life. Ground temperatures up to 330” F were measured. In the early stages of mining, the mine experienced premature detonations using different explosives. The learning curve to safely mine this high-grade gold deposit in hot and severely reactive ground was indeed very steep. Currently, the Meikle Mine uses a special buffered bulk emulsion in all blasts to address hot and reactive ground concerns. In addition, exacting procedures are also followed to ensure safe work with explosives. The combination of new explosives technology and strict loading procedures permits high mine productivity with the highest degree of safety.

Jan 1, 2000

By William Hissem

When we look out on our business landscape today, the words higher, faster, fdwther come to mind. Compliance issues, business integration, increasing production and profitability demands are converging in an age old industry and giving it a new twist. Not that the rock changes, rather that as the variables of our business change, the resulting “cut-off grade in business” turns ore into rock or rock into ore. The trick is to emphasize the latter. As with the miners of yore, what was recovered from the business enterprise had a lot to do with tools and skill. So it is today. When the casual observer looks at drilling and blasting operations today, many see the same basic offering in terms of equipment types and process. Looks, however, can be deceiving. As with the aviation sector, a given machine might took similar to previous generations of equipment, but in fact is radically different in terms of power, efficiency, accuracy, and range. So it is with hydraulic top-hammer drills today.

Jan 1, 2000

By Selamawit Asfaw, Mohamad Sharif

In recent years, the use of modal analysis has increased to include many different aspects of the construction industry. Computer modal analysis can be used in determining the dynamic properties of a structure by mathematical equations and knowledge of the structure’s physical properties. This technique can now be used to predict the level of vibration induced by blasting on adjacent structures. Ground vibration induced by buried explosives is a major concern for contractors when excavating near utility pipelines such as gas and water lines. The size limitations placed on easements causes the necessity of additional utility lines to be placed in close proximity to existing lines. Through the development of computer models of the pipe, stress analysis can be performed prior to blasting. Based on the calculated dynamic properties (natural frequencies and modal shapes) and the maximum allowable displacements and stress levels (which are established by the pipe manufacturer) the allowable maximum charge weight per delay can be selected for the blast. The selected maximum charge weight per delay will ensure that the resulting pipe peak particle velocity level is within 95% confidence. This means, statistically, there exists a 95% probability that the actual pipe peak particle velocity would be less than the predicted value. The pipe is then instrumented with vibration measuring sensors to ensure that vibration levels are within the allowable maximum pipe strength. In conclusion, this technique can assist the engineers and blasters, to establish the proper blast design. It allows for safe and efficient installation of additional utility lines adjacent to existing lines. This technique can also be applied to predict the structural response to blasting induced vibration for a variety of complex structures. A detailed explanation of this technique, as well as an example of application including formulas used for this technique will be provided in this paper.

Jan 1, 2000

By Winfried Rosenstock, Carlos Orlandi

Along the Pacific West coast of Latin America there are several large operations of metal mining activities. To mention only a few: Chuquicamata in Northern Chile moving daily approximately one million t of copper ore and waste, Cerro Verde near Arequipa in Peru, or lanaccocia. Apart from the coal deposits in north-east Columbia it is mainly to deal with metal-mining, which has due to geographical reasons relatively high cash-cost. This sector of mining is traditionally severely depending on the world-market.There are reasons to believe that the world-market will remain on a low price level and some analysts predict that in general the price-level will continue on low basis for the next decade. The cash-cost factor becomes therefore even more important as it already is. The goldprice development during the year 1999 illuminates that market changes can quickly lead to a severe crisis which forces the shutdown of mines with cash-costs close to or above the present market price per ounce. The breakdown of the cash-cost shows, however, that there are ways to overcome even the crisis like it struck the low-grade open pit goldmines around the world. Especially hitherto the “Electronic Option” is the only solution as the possible reduction using advanced technology based on the application of electronic detonating systems and newly developed special ignition procedures. The electronic option will lead to tremendous cost reductions similar to the results of research operations Thiess Contractors, Brisbane, Australia have carried out in Australia in 1998 and 1999. The electronic option allows a comprehensive integration of side effects of the blasting process which in the past could not have been achieved so far. Electronic initiation can achieve secondary effects which have an additional and positive impact on the level of costs. Appropriate application can enhance the production of material which will reduce the primary crusher costs or even make a primary crusher operation obsolete.

Jan 1, 2000

By Jim Smith, Jeff Hudreth, John White

Jan 1, 2000

By Tapan Goswami, Michael Croucher

At Bayswater Colliery various methods of controlling highwall stabii were investigated. The use of presplitting was trialled and its effectiveness measured. The presplit hole spacing and explosive charge were based on those succes& lly used in other coal mines in the Hunter Valley. The major presplit design parameter to be determined was the stand-off distance between the presplit line and the back row of the production blast. This could not be transfmed directly from other sites due to the difference between the Bayswater’s production blast geometry and geology to that of other sites. Using highwall face surveys and Orica’s SUR..YPlus@ software, the average back-break behind normal production blasts was determined. This was then used to select the stand-off distance between the back row production blastholes to the presplit line. While presplit designs are normally based on powder factor (kg/m2), the use of energy factor (MJ/m2) was also investigated as a possible design criteria.

Jan 1, 1999

By Bryan J. Lane, Paul N. Worsey

The recommended maximum explosive weight for boulder blasting using internal charges is 0.1 O-kg/m” (3.5 oz./yd) (Olofsson, 1988). Normally this charge results in excessive scattering and flyrock, creating increased liability for the operator, especially in congested areas. An alternative technique using smaller explosive charges is being developed at the University of Missouri - Rolla. It is designed to reduce boulder scatter, flyrock and fumes and allows shooting in close proximity, using common blasting products.

Jan 1, 1999

By Melvin A. Sannes

The explosives industry is recognized as one of the most dangerous occupations in the world, yet it is rare to see actual training procedures. As our industry becomes increasingly technical, it is imperative that we train the personnel in OUI industry properly.

Jan 1, 1999

By Sarma S. Kanchibotla

In overburden cast blasting the explosive energy is used to move a significant percentage of overburden from the high wall to the spoil pile thus reducing the amount of material to be handled by machinery. However, the obvious trade-off between the extra explosive energy in the cast blast versus reduced dragline effort is complicated by an increased risk of damage to the underlying coal. This damage may not be obvious but inevitably leads to reduced coal recovery and may negate much of the benefit sought from cast blasting.

Jan 1, 1999

By Mo Jadbabaei, Scott Harrison

There is very limited information available regarding the air pressures, flow rate, and velocity profiles in blast hole air drilling applications. Currently, many people are using incompressible flow correlation to calculate the bailing velocity. In this article, air pressure, flow rate, and velocity profiles are calculated using compressible flow theory. The airflow at the bottom of the hole is simulated using the jet flow theory. The concept of choking condition is introduced, and it is concluded that the velocity at the nozzle exit cross section cannot exceed sonic velocity. The minimum pressure required for achieving choked condition at the nozzle cross section is calculated. Choked and overchoked flow conditions at the nozzles are examined, and the maximum achievable cleaning power is correlated to the nozzle size and pressure.

Jan 1, 1999

By Yang Ruilin

Bulk gassing technology is a growing trend in the commercial explosive industry. The gassed bulk products produced differ from microballooned bulk products or cartridged products. It is easy to know the loaded or in-hole density for microballooned bulk products or cartridged products, whereas it is not as straight forward to know the m-hole density for gassed bulk emulsions. The loaded density is one of the key parameters affecting explosive performance and therefore it is important to have a field technique to monitor the in-hole properties of gassed bulk products in order to accurately predict the blast performance and to ensure efficient use of the products.

Jan 1, 1999

By Jean-Guy Levaque, Robert Ethier, Ron J. Elliot

This paper presents data gathered during a comprehensive study on the impact of improvements to fragmentation in a major Limestone quarrying operation. The full impacts of gains in fragmentation are tracked through the mucking, crushing, and grinding phases of the operation.

Jan 1, 1999