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By R. Alford

In the modern world of demolition safety is paramount and unnecessary or unquantifiable risks are not accepted (FasterCapital, 2024) and all risks must be kept As Low As Reasonably Practicable (ALARP) (BSI, 2017). This principle has led to a huge reduction in deaths in the last 50 years and the statistics continue to improve although this is starting to plateau (Beal, 2007). Under normal circumstances, this is now simply part of the normal way work is done and systems are in place to ensure both safety and economic profits are assured. What happens when the environment is less controlled and risks are unknown, such as after a natural disaster, war, an accident or a stand-up from a failed demolition attempt? A dangerous structure cannot responsibly be left alone with a fence around it so some action must be taken, but how can this be done safely and responsibly? An incident in Didcot, England in which half of a power station’s boiler house being prepared for an explosive demolition collapsed suddenly, killing four men in 2016 provides a useful case study of how technology, creativity and planning can be used to conduct complex demolition fully remotely to avoid any further risk to life.

Jan 21, 2025

By Scott G. Giltner, Alex Schwenk

This paper is an update on a paper presented at the 2022 ISEE conference. The original paper presented how the mine operator desired to open up ore reserves near several mine structures including two crushers, the conveyor belt drive and the concentrator thickeners. In order to open up additional ore for extraction (over 3 million long tons or 3 million tonnes) it was necessary to blast out two benches near the mine structures. Since the two benches have been successfully shot, the mine has now conducted nine production blasts in this area at distances as close as 116 m (380 ft) to the two primary crushers. These production blasts are full size production blasts consisting of up to 300 or more blast holes. For these blasts the two primary crushers were still the critical structures as they were the production life blood of the mine. If the crushers were shut down due to any damage from the blasting, the revenue of the mine would be adversely affected. As with the initial bench blasts, two issues provided an extra challenge to the blast design. The first was that the blast holes were still considered large diameter at 12¼ inches (311 mm) and 16 inches (406 mm). The second issue was that the bench heights were short, with the average varying from 34-40 ft (10.3-12.2 m). This combination of large diameter blast holes with a short bench provided an unfavorable geometry for the goals established by the mine management. The mine management established the following goals. 1) None of the mine structures would be damaged by fly-rock. 2) Minimize the blast vibrations at the crushers. 3) The last goal was to produce a muck pile that could be dug easily by hydraulic shovels. Electronic detonators were applied to achieve the necessary control of the blast and optimal fragmentation throughout the mine. UAV surveys of the blast area were also conducted to provide a 3-D representation of the free faces and bench surface. The 3-D point cloud produced from this was used to measure the shape of the free faces. Once the shape of the free faces was quantified, it was possible to establish proper placement of the crest holes and develop a custom explosive load for each blast hole. The results of the nine blasts have provided what the customer requested. The peak vibration level at the crushers for the nine production blasts was 1.6 in/s (40.6 mm/s) at a frequency of 18.9 Hz. There have been no fly-rock or blast vibration issues at any of the nearby mine structures. As a result, the mine has been able to maintain its production with no downtime. The muck piles have been well fragmented with reports from the shovel that they have all dug well.

Jan 21, 2025

By Hector O. Romero, Paulo C. Fernández A, Claudio C. Gajardo

Phase 06 of the Los Bronces mine, currently under extraction for development, has the particularity of being close to the installations and buildings of a neighboring copper mine. Therefore, the blasts must ensure the continuity of the operation without affecting the nearby structures of the neighboring district, which include Maintenance sheds and Warehouse. Specifically, the safeguards consider a scenario that includes: - Flyrock projections (<150m) - Edge profile studies - Vibrations according to the NCh3577 standard - Nitrous gases Additionally, Phase 06 is also within Los Bronces, so strict control over spillage into the pit is necessary to avoid blocking ramp access to this level. The challenge lies in protecting not only the operation and facilities of the neighboring mining district but also the operability of Los Bronces. Thus, addressing these considerations, blasting configurations are developed with prior simulation of vibration models, flyrock, and spillage in all blasts, with strict control of technical design and implementation to ensure the results. Currently, blasts are successfully executed with control of projections based on the proximity of the projects, vibration (<40mm/s) with decoupling of holes of 17 mm/s between holes, reactive rock tests for explosive selection (loading advancement), and spillage simulation inside the pit according to the loading design; thus, ensuring operational continuity and mine development.

Jan 21, 2025

By Orica Peru, Pedro Lozada

Maintaining a continuous mining process during thunderstorms is one of the primary challenges in Peru's open-pit mines. Safety protocols necessitate the establishment of exclusion zones to minimize the risks of unplanned detonations. During such conditions, loading and hauling equipment must be relocated or, in the worst case, halted, directly affecting productivity (t/h). Implementing a wireless initiation system mitigates the risk of unplanned detonations during electrical storms by eliminating the use of electrical cables that are susceptible to electrical discharge. This study documents the implementation of this system in a copper mine located over 3,500 meters above sea level in Peru, where electrical storms between December and March necessitate modifications to blasting schedules and limit the number of drills fired per event. Through a test using wireless detonators, a key performance indicator (KPI) was established to ensure safe and continuous operation during thunderstorms. The results were significant: 20 blasts were successfully executed, firing approximately 5,000 holes and moving around 10 million tons of material, all without safety incidents or critical operational deviations, achieving zero misfires and no scheduled blast suspensions. Shovels SH001 (ore) and SH002 (waste) continued to operate together for an additional 100 hours continuously during thunderstorms, generating a potential saving of USD 3.3 million by continuously sending ore to the plant during the testing period under stormy conditions. Additionally, the blasting initiation time was reduced by 25%, eliminating two activities that involved the use of surface connection cables. This reduction led to over 150 hours of decreased personnel exposure to interactions with vehicles and environmental hazards such as dust and noise. Furthermore, the number of holes fired in a single event increased by 50%, enhancing the blast tonnage capacity and reducing equipment stops due to evacuation and reentry from two to one.

Jan 21, 2025

By Hernan Navea, Carlos Alvarado, Exequiel Nuñez, Matías Suarez, Jhon Silva, Bryan Townsend, Bryan Caceres, Felipe Pontanilla

Nowadays, technology dominates all aspects of human activities, and drilling and Blasting (D&B) is no exception. In most cases, the use of technology in D&B is focused on controlling individual activities such as drill performance, drilling advance rates, truck loading performance, etc. Still, in very few instances, the advantages of using technology along each D&B activity and how this influences the D&B results are documented. This paper shows how technology is applied to create a “relative hardness” model for the mine Caserones in Chile. In the future, the model can relate the relative hardness parameter to several variables, including excavation rate, fragmentation results, and vibrations. It can also be used in the explosives loading process, similar to the model used by Dyno Nobel’s Differential Energy (DE) technology. In the relative hardness model for Caserones, a design is loaded in the drill system, and data is collected during the advance of the blasthole. The collected data includes rpm, torque, pressure, etc. Then, an algorithm using the measured variables while drilling and known relationships between the properties of the rock and the drill's performance is used to classify the average relative hardness of the blasthole in four intervals: hard, medium, soft, and very soft. Optimization techniques and models used in the oil and gas industries to analyze drilling performance were adapted to implement the algorithm. The model uses the concept of mechanical specific energy (MSE). Using the data from the drill, the algorithm identifies the depth where the MSE reaches a minimum to calculate the “relative hardness” for the blasthole under analysis. The results are presented in maps highlighting the areas where hard, medium, soft or very soft rock masses are expected. That information can be used to anticipate areas where explosives with higher energy need to be used or to predict areas of the blast with additional digging difficulties and then lower loading rates. The paper shows examples where “relative hardness” maps are compared to drilling speed excavation rates and other variables.

Jan 21, 2025

By Daniel Richards, Dr Rob Farnfield, Dr Geoff Adderley

The 8-millisecond rule has been in use for many years as a basic technique to help minimize vibration levels from surface blasting operations. The rule was based on work carried out in the 1960’s by the USBM by recording the vibration levels from a series of test blasts in a quarry over a range of distances. This work included the firing of a series of single hole blasts and a number of single row production blasts using a variety of inter-hole delay times. The delay times employed were limited by the technology available at that time to instantaneous, 9, 17 and 34 milliseconds. There have been several papers in recent years suggesting that the use of the 8-millisecond rule is no longer required, when using electronic detonators, due to their enhanced accuracy and greater initiation pattern design flexibility. This paper examines this proposition by revisiting the original work and employing the linear superposition technique to reprocess some of the original recordings. Similar techniques are then applied to a large database of single hole vibration recordings for a range of rock types, distances, and number of decks, with calculated reinforcements compared to the minimum separations in typical patterns. The results suggest that there is some validity to the 8-millisecond rule when applied to electronic detonators but not in the way it is traditionally applied. Simple guidance is suggested for those designing blasts with electronic detonators to minimize vibration levels even if the benefits of linear superposition trials are not available.

Jan 21, 2025

By Bilegt Batbold, Bayu Saputra, Chris Batten

The ability to fire multiple blasts simultaneously can provide significant benefits to any open pit mining operation. Reduced blast-related downtime by reducing blast events can increase equipment utilization and maximize material movement. Significant sequencing benefits can also be delivered, associated with reduced equipment relocation. This paper describes the work completed in partnership between Orica and Oyu Tolgoi to successfully demonstrate that combined production-trim and midsplit blasting could be implemented successfully while successfully managing the risk of increased damage to the final walls. The paper details the methodology used to assess key performance measures linked to final wall damage and compares the performance between the following blasting methods. • Free face trim blasting vs. combined production-trim blasting • Presplit blasting vs. midsplit blasting. The results of the initial trial blasts are presented, along with the method agreed by the key site stakeholders for ongoing application. The method used to keep the risk of final wall damage to an acceptable level is explained, along with the benefits delivered to Oyu Tolgoi operations associated with the initial 12 months of application.

Jan 21, 2025

By M.P. ROY, ASHISH K. VISHWAKARMA, A.K. MISHRA, P.K. SINGH, VIVEK K. HIMANSHU

Principal component analysis (PCA) is one of the dimension reduction techniques widely used to classify data based on features. Ground vibration is a major hazard arising from rock blasting operations, and accurate prediction of the vibration is necessary for designing controlled blasting parameters. Most of the widely accepted predictors of ground vibration consider the maximum explosive charge weight per delay (MCPD) and distance as the parameters responsible for ground vibration, but mining sites with bigger production targets have varying geometrical parameters to suit the excavator utility. Accordingly, other blast design parameters will also have impacts on ground-vibration intensity. A blast vibration predictor considering all the blast design parameters would be complicated, and some of the parameters will have overlapping contributions to ground-vibration intensity. Data classification using PCA is a feasible solution, and regression analysis may be performed to develop predictors using the classified input data. In this study, PCA was used along with multivariate logarithmic regression to predict ground vibration, and the performance of this technique to predict ground vibration was compared with the performances of various existing empirical predictors. The evaluation suggests that the predictor with logarithmic regression followed by PCA performs better than the existing empirical predictors.

Nov 1, 2022

By Lihong Zhou, DAVOOD BAHRAMI

A reliable and stable ventilation system is essential to the safe operation of underground mines. The stability of a mine ventilation system becomes extremely critical when responding to a fire incident, as an unstable ventilation system will pose a risk of airflow reversal. The reversed airflow could bring fire contaminants, such as toxic gases and smoke, unexpectedly to working areas. In the past few years, there has been a growing interest in the study of ventilation network stability using the concept of resistance sensitivity, which is described as an indicator of how the airflow in an airway is reacting to a resistance change of other airways. Several methods of calculating the resistance sensitivity in a mine ventilation network have been developed by researchers and scholars around the world. However, those proposed methods rely heavily on a vast number of mine ventilation simulations, which is time-consuming and computer-resource intensive, especially for a large-scale mine ventilation network. In this study, a derivative method calculating the resistance sensitivities with a single mine ventilation simulation is developed and implemented into the MFIRE mine fire simulation software. The results from the derivative method were verified against the results from a traditional method. The derivative method is proved to be reliable and accurate.

Dec 1, 2022

By CORNELIUS STEPHANUS LODEWYK SCHUTTE, WIEHAN ADRIAAN PELSER, JEAN HERMAN VAN LAAR, MICHAEL DAVID HARMSE

Rising electricity costs in South Africa have resulted in a need for optimized compressed-air networks in the mining environment. As a result, the financial benefit of air receivers needs to be reconsidered along with the economic dispatch strategy. This study investigates the use of an evolutionary algorithm in the mining industry to determine the potential financial benefit for various-sized air receivers, as well as their dispatch strategy. A genetic algorithm was selected due to the improved solution reliability and accuracy compared to other optimization techniques. This study indicates that a genetic algorithm can be used to determine the optimal dispatch of compressed air in the deep-level mining industry. Further, this study indicates that air receivers are financially viable in the mining industry and can be used to reduce operating costs, improving profitability.

Dec 1, 2022

By SONGHE WANG, YI XUE, PENG HOU, CAIHUI ZHU, XUANYE JIAO, Feng Gao

Coalbed methane development is an important way to effectively realize a source of clean energy and reduce emissions of carbon dioxide and other gases. However, due to the low permeability of coal seams, the development of coalbed methane in China has encountered substantial barriers. Protective layer mining can efficiently minimize in situ stress and increase coal seam permeability, thus improving gas drainage and avoiding gas disasters. This study analyzed the characteristics of gas migration and the change in permeability during the in situ stress releasing process through experiments and numerical simulation to study the gas drainage effect of a coal mine in an unloaded coal seam under specific geological conditions. First, a stress–strain-seepage coupled test of coal was carried out, and the evolution features of coal permeability during stress loading and unloading processes were investigated. Second, experimental results were used to develop a mathematical model of coal seepage under mining unloading conditions. Finally, a numerical model was developed based on the real geological conditions of the Wulan coal mine to explore the characteristics of in situ stress release and permeability evolution, as well as the gas drainage process in an unloaded coal seam. By combining protective layer mining and gas drainage technology, the risk of gas outburst is significantly reduced.

Oct 1, 2022

By DEVY DYSON, Brian Hart, JOHN LANGHANS, Stamen Dimov, STEVE YOPPS

A recent Nevada Gold Mines research program focused on the pressure oxidation (POx) pretreatment of a Carlin-type double refractory ore from the Turquoise Ridge Mine. The research team found that both arsenian pyrite and carbonaceous matter were highly oxidized within an hour at 300 °C using a bench-top autoclave reactor and that the gold recovery from the residues after cyanide/carbon-in-leach (CIL) approached the technical limit set by the amount of gold encapsulated by silicate minerals. Although the 60-min pretreatment at 300 °C yields robust performance when treating a whole ore, copper additives can catalyze the oxidation rate of carbonaceous matter and reduce the residence time needed at elevated temperatures. Certain gangue minerals are susceptible to dissolution in acidic solutions at 300 °C, and this may cause poor gold recovery. This recovery challenge is mitigated by keeping free acid in the discharge solution below a key threshold.

Nov 1, 2022

By NEHA PANDEY, V.K. REDDY KALLAM, SUNIL KUMAR TRIPATHY, ARIJIT BISWAS

This work discusses the sulfur dioxide (SO2) leaching of low-grade ferruginous manganese ores to selectively recover manganese (Mn) as manganese sulfate (MnSO4), followed by electrowinning of the purified MnSO4 to produce electrolytic manganese dioxide (EMD). The effects of the leaching process parameters on Mn recovery were studied, and the leaching duration and SO2 flow rate were found to have significant effects. Under the optimum conditions derived for grade 1 ore (with total Mn content of approximately 17.16 percent), the specific SO2 requirement (SSR) — that is, the SO2 flow rate per gram of Mn in the leach slurry — was calculated to be 0.014 L/min. At the SO2 flow rate calculated using SSR for grade 2 ore (with total Mn content of approximately 26.29 percent), a Mn recovery rate of 94 percent was realized. Electrowinning of the purified MnSO4 generated after leaching resulted in EMD with 88.01 percent purity and a γ structure.

Sep 1, 2022

By DEBASHISH MISHRA, SOMU MANDAL, ASFAR MOBIN KHAN, JAI KRISHNA PANDEY, NIROJ KUMAR MOHALIK, SANTOSH KUMAR RAY

Coal is a low-cost fuel with high calorific value. Statistically, the global coal mining industry suffered 12,489 fatalities in 104 reported mining accidents from coal dust explosions during 1900 to 2020. This review article discusses the occurrence, mechanism and explosibility parameters of coal dust explosions and presents a literature survey of the laboratory and computational fluid dynamics (CFD) simulation methods of studying them, as well as a comparison of the two methods.

Feb 1, 2023

By GRANT COLLIGAN, BROCK O’KELLEY, Corby Anderson

With the world’s ever-growing push to expand technological capabilities, the need for specialized materials including rare earth elements has exploded. One source of rare earths found in the United States is bastnaesite, a rare-earth-bearing fluorocarbonate, mined at the Mountain Pass Mine in California. To increase production, it has been essential to optimize existing processes and create new ones to capture current reserves. This paper presents the results of a research program conducted to expand the understanding of the bastnaesite leaching system. With the help of prior knowledge and thermodynamic calculations, a novel single-stage hydrochloric acid leach system was created to optimize the extraction of rare earths from bastnaesite. Historically, this extraction has entailed the use of a two-stage leach system involving a high-temperature hydrochloric acid leach followed by a caustic crack. We ran a series of single-stage leach experiments by reacting locked-cycle flotation concentrate with hydrochloric acid to test common leaching parameters. The results of these single-stage tests showed significantly higher rare-earth recoveries than the reported recoveries of the historic two-stage caustic crack processes, all while decreasing the number and amount of reagents needed.

Feb 1, 2023

By VIVEK KASHYAP, EVODY TSHIJIK KARUMB, PATRICK TAYLOR

Zinc ferrite is considered an integral phase of zinc residues as their presence can render the processing of zinc and critical metals difficult. It is a refractory phase, formed at high temperature in the presence of zinc (Zn) and iron (Fe) during oxidative roasting in zinc processing plants. Because it is refractory to efficient leaching, unreacted zinc ferrite gets concentrated in the final zinc residue, making it a viable source of zinc and indium extraction. The refractory nature of zinc ferrite makes the extraction of associated critical metals difficult. In order to explore a potential economic and carbon-neutral zinc ferrite processing technique, our previous study proposed the partial reduction of zinc ferrite followed by sulfuric acid leaching of the roasting product [1-3]. As demonstrated in our previous studies, partial reduction of zinc ferrite results in a mixture of ZnO, Fe3O4 and FeO, which can be further subjected to leaching for efficient extraction of zinc and critical metals such as gallium and indium.

Dec 1, 2022

By ERIK C. WESTMAN, JESSICA M. WEMPEN, DALLAN J. COONS, WILLIAM G. PARISEAU, MICHAEL K. MCCARTER

Safe, efficient underground mining is dependent upon proper pillar sizing. Pillar sizing is typically based on a combination of observation of prior behavior, point measurements, theory and numerical modeling. The actual stress redistribution within a pillar, while assumed for many years, has rarely been imaged. Such imaging can help confirm whether or not theoretical and numerical modeling methods agree with actual conditions within a pillar. This research presents a case study from a longwall mine in the western United States. A two-entry, gate-road yield pillar in the headgate of the mine was instrumented with seismometers and convergence monitoring stations, and was monitored over a period of about six months as the longwall face approached the pillar. In this paper, the stress distribution imaged using seismic tomography is compared to the stress distribution expected from theoretical models, geotechnical measurements and numerical models. The tomography results generally agree with those proposed by theory, convergence measurements and numerical modeling results. The agreement of the methods provides validation for the theorized stress redistribution, and this study provides further evidence that tomography can indicate the redistribution of induced stress within a mined rockmass and is another tool available to ensure that mining is conducted safely and efficiently.

Aug 1, 2022

By Yong Pan, SRIVATSAN JAYARAMAN SRIDHARAN, Purushotham Tukkaraja

The block cave mining method poses unique ventilation challenges compared to other underground metal mining methods. This research study focuses on assessing the airflow behavior in regulated airflow distribution systems by developing a 1:100 scaled block cave experimental model and a numerical model. This study also investigated gas flow behavior under various airflow conditions. Based on our findings, we observed that reduction in particle size and porosity of caved materials, decrease in cave footprint, and closure of undercut drifts would increase cave airflow resistance. The increased airflow is found to be beneficial for gas dilution regardless of its source locations, while the regulated airflow distribution system might deteriorate the gas dilution situation when the source is located in the extraction drifts.

Sep 1, 2022

By RICHARD A. THOMAS, Liming Yuan, Lihong Zhou, DAVOOD BAHRAMI

Mine ventilation simulation software has become an essential tool for the mining industry to design and manage mine ventilation operations. Building a well-calibrated mine ventilation network is time consuming, however, and requires great effort. In the last several decades, the mining industry has seen a steady increase in the use of air velocity sensors to monitor airflow and detect unexpected abnormal airflow in some key locations in underground mines. The present research work was carried out to explore the possibility and methodology of calibrating a ventilation network model using atmospheric monitoring system (AMS) data on a routine and ongoing basis.

Aug 1, 2022

By PATRICK R. TAYLOR, NICHOLAS BELLUSCI, D. ERIK SPILLER, VICTOR BRAMAN

Most of the world’s production of natural soda ash comes from the mining and processing of trona found near Green River, WY. The processing of trona ores to ultimately yield a high-quality dense soda ash product and reject the insoluble gangue species, primarily in the form of oil shale, is water and energy intensive. It is speculated, however, that the glass-manufacturing industry, which is the largest consumer of soda ash, may be able to use product of a lower grade and consistent level of the insoluble constituents. Thus, the viability of using sensor-based sorting to produce a beneficiated trona stream that would be fed to calcination was investigated. The study encompassed the preparation of a run-of-mine (ROM) Green River ore sample; selection of specimens sized 25 to 75 mm; imaging of the specimens by sensors based on X-ray transmission (XRT), color and laser-induced fluorescence (LIF); insolubles analysis of the specimens; and a bench-scale sorting test. Results of the study established that a correlation between the color of the individual ore particles and their insoluble content exists, and that a surface-detection-based sensor, particularly LIF, is apparently more suitable than XRT to produce a beneficiated trona stream. The bench-scale sorting test demonstrated that a 65 percent separation efficiency and a 70 percent recovery of trona could be achieved.

Feb 1, 2023