Watkins, CO, United States
Watkins, CO, United States

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Yang R.,Orica United States Inc. | McAllister C.,Simplot Phosphates LLC | Berendzen J.,Southwest Energy Inc. | Preece D.,Orica United States Inc.
Mining Engineering | Year: 2016

The Multiple Blasthole Fragmentation (MBF) model models multiple explosive charge contributions and the effect on fragmentation of delay timing with its associated scatter for each blasthole. The model uses near-field blast vibration attenuation parameters and the ground p-wave velocity as inputs for part of the in situ rock property to model rock fragmentation. It models most blast design parameters explicitly and simulates the effect of wave reinforcement due to the interaction of simultaneously arriving waves or diminishing cooperative contribution from long delay intervals between charges within a blasthole or among blastholes. The fragmentation size is calculated at three-dimensional grid points within a blast, and the fines and oversized blocks are treated explicitly. The model takes a surveyed irregular geometry of the free face of a blast as the calculation boundary. This paper presents a case study on applying the MBF model at an openpit mine. Near-field vibration measurements from signature hole blasts were conducted to obtain the stress-wave magnitude and attenuation parameters as well as ground sonic velocity. A production blast was then monitored with the corresponding fragmentation measured, serving as site-specific inputs to the MBF model. Various blast design scenarios were then simulated to develop ones that provide better fragmentation to improve mill throughput for the mine.

Lownds C.M.,Orica United States Inc. | Steiner U.,Orica Germany GmbH
SME Annual Meeting and Exhibit 2010 | Year: 2010

Electronic detonators have been in commercial use for a decade, with an excellent safety record. This paper lists known incidents involving electronic detonators. Typical standards required by regulatory bodies for static electricity and electromagnetic fields are reviewed. The performance of some detonators is compared to these standards; in general the minimum standards are easily exceeded. The general resistance of electronic detonators to extraneous electrical energy that can be derived from the body of test results is compared to danger levels for exposure of humans to these energies; it is shown that electronic detonators can safely tolerate higher electrical energies than people can. This comparison includes comparable data for electric detonators, which are shown to be more vulnerable to extraneous electrical energy than people are. Electronic detonators also bring significant safety benefits in blasting due to their testability, two-way communications, reliability, programmability and precision. The links between these attributes and enhanced safety are discussed with examples from actual blasting. Although electronic detonators are usually more vulnerable to extraneous electricity than non-electric initiation systems, the paper shows that the net safety benefit in handling and blasting is in favor of electronic detonators, which are the safest initiation system that has ever been offered to the mining industry.

Preece D.S.,Orica United States Inc. | Yang R.,Orica United States Inc. | Pilz J.,Rio Tinto Technology and Innovation | Zavodni Z.M.,Rio Tinto Technology and Innovation
Rock Fragmentation by Blasting - Proceedings of the 9th International Symposium on Rock Fragmentation by Blasting, FRAGBLAST 9 | Year: 2010

An overland conveyor was constructed at a surface coalmine to reduce the truck haul distance and make the operation more efficient. An important element in this system is a truck dump facility to transfer coal from truck to conveyor. The coal is dumped from above and processed through a crusher before loading onto the conveyor that carries it to the coal processing facility. The configuration of the mechanically stabilized earth (MSE) retaining wall is typical of many mining operations and utilizes a series of MSE walls surrounding a crusher to create a "pocket". The Owner requested that the potential for blast vibration damage to the wall be assessed and criteria developed to reduce the potential for blast induced damage. This paper presents the methodology used to assess such blast effects, a comparison to measured values and demonstrates the conservatism inherent in simplistic earthquake based analysis. © 2010 Taylor & Francis Group.

Yang R.,Orica United States Inc. | Scovira D.S.,Orica United States Inc. | Patterson N.J.,Orica Canada Inc.
Rock Fragmentation by Blasting - Proceedings of the 9th International Symposium on Rock Fragmentation by Blasting, FRAGBLAST 9 | Year: 2010

In an urban production quarry, blasting close to a city boundary requires management of the vibration peak particle velocity of vector sum (PVS). Blasting is required to come within 30 meters of the boundary. An optimal technical solution was obtained through an integrated approach of signature hole vibration monitoring and modeling. A series of signature holes were fired and full vibration waveforms from these holes were recorded with several seismographs at distances ranging from 20 to 100 meters from the signature holes. Following the signature hole vibration monitoring, several production blasts were monitored with an array of seismographs. A vibration model using multiple seed waveforms for a point of interest was applied to the case assisting in the selection of blast design parameters. The selected blast designs were implemented and are proving to be effective in managing the vibration below the limit while maintaining high productivity. The capability of the model in terms of the PVS of particle velocity and frequency predictions is demonstrated in the paper. With the signature hole data as the input to the model, the model prediction agrees well with field measurements of PVS of particle velocity and amplitude spectrum from production blasts. © 2010 Taylor & Francis Group.

Yang R.,Orica United States Inc
International Journal of Energetic Materials and Chemical Propulsion | Year: 2011

This paper studied the density effect of the gassed emulsion product on the resistance to static and dynamic precompression. The study revealed that the resistance to precompression of a gassed emulsion is controlled by the void ratio (density) of the product. When the void ratio of the product is below 14%, the resistance to dynamic precompression is only 2000 psi (13.8 MPa), under which the product was dead pressed (failed to initiate). When the void ratio of the product is above 21%, the resistance to dynamic precompression is found to be superior to strong glass microballoon product. However, the current perception that gassed emulsion has an ability to recover from precompression to detonate within a few milliseconds aftershock is not supported by experiments. The resistance to static pressure of gassed products was also measured and found to decrease with the decrease of the void ratio ranging from 24 to 10%. Tests in the study were mainly conducted in a laboratory. A field trial was conducted with specially designed blast pattern and firing sequence. © 2011 by Begell House, Inc.

Yang R.,Orica United States Inc. | Wiseman T.,Orica United States Inc. | Scott Scovira D.,Orica United States Inc.
International Journal of Mining and Mineral Engineering | Year: 2011

Most existing blast vibration models are designed for far-field vibration using a single seed wave to represent each blasthole within a blast for a point of interest and do not simulate wave shape change over the distance. Without modelling the waveform change, such models cannot reliably predict the amplitude and frequency of the blast vibration from a production blast. A multiple-seed blast vibration model (MSW) developed within Orica in recent years is suitable for near and far-field blast vibration. With the recent development, it is also applicable for open pit and underground blast vibrations including tunnel blasting. This paper updates the current capabilities of the MSW model with selected case studies. Copyright © 2011 Inderscience Enterprises Ltd.

Pinksen R.,Iron Ore Company of Canada | Proulx J.P.R.,Orica United States Inc.
IRON ORE 2011, Proceedings | Year: 2011

The Iron Ore Company (IOC) of Canada Mining and Operations Departments expressed an interest in reducing the amount of oversize material (>1 m × 1 m × 1 m) being produced and its subsequent downstream effects including in-pit sorting and reduction, damage to mobile equipment, and signifi cant delays in the loading pockets and the primary crushers. To achieve this goal an oversize reduction project was undertaken by the mine and to date has signifi cantly improved upon baseline measures. One key approach used to reduce the amount of oversize was the implementation of thicker emulsion. The introduction of a thicker emulsion into the blastholes provided more resistance to the forces created by dynamic water and reduced the infi ltration of the emulsion into the cracks and fi ssures of the rock mass. Blast results showed reduced amounts of oversize and more consistent fragmentation throughout the muck piles. Additionally, a signifi cant reduction in nitrates leached into the mine water discharge has been realised. To determine the effectiveness of the oversize reduction project, IOC used shovel based camera technology to assess fragmentation presented to the shovel at the digging face. A digital vision system (DVS) was installed on one of the shovels to capture images that were stamped with global positioning system (GPS) locations. A large population of digital images was analysed to produce a robust fragmentation distribution baseline that was used as one of the mine key performance indicators (KPI). Changes to blasting practice were subsequently measured against the baseline KPI to assess effectiveness.

Yang R.,Orica United States Inc. | Ray K.,Orica United States Inc.
Rock Fragmentation by Blasting, FRAGBLAST 10 - Proceedings of the 10th International Symposium on Rock Fragmentation by Blasting | Year: 2013

Blast vibration is essentially strain/stress wave propagation in rock or structures in the vicinity of a blast. However, blast vibration has always been quantified in terms of Peak Particle Velocities (PPV) or Accelerations (PPA) and a meaningful relationship between blast vibration and strain/stress has not been established. Consequently, there is no consistent method based on fundamental mechanics to determine a vibration limit for a particular operation. The determination of the dynamic strain from blast vibration may improve the quantification of blast damage and the selection of blast vibration limits for critical structures including highwalls. This is because dynamic strain relates to rock mechanics or material strength more directly than Vibration Particle Velocity (PPV). This paper documents a method to calculate three-dimensional dynamic strain from recorded blast vibration signals. The method is based on the determination of the displacement gradients at a small area of interest. The mathematical analysis and the results of the field monitoring of blast vibration are discussed in the paper. The paper also discusses the conditions when the one-dimensional and two-dimensional strains can be measured from blast vibration. The method is applicable to production blasts with multiple blast holes. Field testing of the method showed that dynamic strains determined from blast vibrations are within theoretical expectations. The various strain quantities in the paper derived from the measurement, such as maximum tensile, maximum compressive, maximum shear strains, may be used to describe potential blast damage to the high walls or rock slopes. Such quantities are more meaningful to a rock mechanics engineer than PPV alone. The analysis of the strain quantities also showed that the commonly used assumption by the blasting community that the PPV is proportional to the dynamic strain may not be always true because the dynamic strain is related to the displacement gradients which are affected by the vibration frequency. The dynamic strain measurement may advance the capability to control blast vibration and damage. © 2013 Taylor & Francis Group.

Yang R.,Orica United States Inc. | Kay D.B.,Orica
Tunnelling in Rock by Drilling and Blasting: Workshop Hosted by FRAGBLAST 10 - The 10th International Symposium on Rock Fragmentation by Blasting | Year: 2013

Blast vibration control is of vital importance for tunnel blasting in urban environments. Due to the expensive nature of urban tunnelling projects, it is always necessary to maximize excavation productivity while controlling the blast vibration under prescribed limits. Using field tests to explore various design scenarios is time consuming and costly. It is worthwhile to use a reliable computer model of blast vibration to assist in selection of blast design options to maximize each blasting opportunity. A project was conducted to test a blast vibration prediction model for tunnel blast vibration. A series of tunnel blast rounds were fired and tri-axial vibration waveforms from the blasts were recorded with several seismographs at distances ranging from 10 to 100 metres from the blasts. Seed waveforms were obtained from the cut holes in each round. Over 60 seed waveforms were collected and the charge weight scaling law for the signature hole PPV was established. A vibration model with Multiple Seed Waveforms (MSW) as input for a point of interest was developed in recent years by the present authors. The MSW blast vibration model has been applied successfully in open cut and quarry blasting situations. From the literature, it appears that there may not be any seed wave based vibration modeling work for tunnel blasting. In this paper the MSW model is applied to tunnel blasting and some specific issues associated with tunnel blast modelling are addressed. The capability of the model in terms of the PPV and frequency prediction is demonstrated in the paper. The paper demonstrates the MSW blast vibration model is a useful tool for managing tunnel blast vibration with the potential to optimize round by round design. A few of the design scenarios were modelled and the results are discussed in terms of managing the vibration below the limit while maximizing tunnel advance rate.

Yang R.,Orica United States Inc. | Preece D.,Orica United States Inc.
49th US Rock Mechanics / Geomechanics Symposium 2015 | Year: 2015

All rock excavations by means of natural gravity caving, mechanical excavation or blasting cause redistribution of the static stress and strain in the remaining rock mass. It is critical to measure the change of the strain state. Such a measurement can serve as quantification of the damage and of the effectiveness of a blast design or an excavation method. Secondly, the measurement can be used to monitor slope or mine structure stability to improve the mine safety. At present, there is no method available to calculate strain changes over a large area of a rock slope or an underground structure. New technologies developed over the last few decades; such as GPS, radar systems, three dimensional photogrammetry and multi-sensor displacement monitoring, are also used nowadays to monitor displacement. If a strain calculation method is developed, the data may be used to calculate distributions of three dimensional strain tensors in the slope or highwall. Without a strain calculation method, the data can only give displacement change at discrete monitoring spots. This paper presents a method for measuring the change of the static strain state at a remaining rock mass or ground associated with operations of excavations, such as blasts, mechanical means or gravitational caving of a portion of the ground. The method is based on measuring coordinates of selected points with recent accurate survey techniques before and after an excavation. The paper also shows that for small deformation the different reference points for survey before and after an excavation can be used, which provides great convenience in practical measurement. The calculation of the strain change is done by solving a set of simultaneous equations for the displacement gradients. With the number of survey points larger than the minimum number required, the number of the independent equations is greater than the number of unknowns and minimizes measurement errors.

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