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By Jeremiah Cohn, Rachel L. Bauer, Catherine E. Johnson

Water is frequently used in explosive applications to increase explosive performance and reduce air overpressure. Water tamping can enhance cutting abilities of shaped charges in demolition and increase impulse of kicking or breaching charges. In explosive disposal, water is used to suppress air overpressure and reduce noise. Despite its widespread use, the specific effect of water placement, whether in front of or behind the explosive, has not been studied. This work evaluates the directional effects of water placement on blast performance using 400-gram sheet explosive charges in five configurations: no water (control), rear-only water (tamped), front-only water (pushed), water on both sides (confined), and a thin front-and-rear water layer (low mass confined) to assess reduced mass effects. Water was sealed in plastic bags and held in position with custom 3D-printed cages to ensure consistent geometry and contact. A modified ballistic pendulum consisting of a hanging steel W-beam was used to evaluate impulse transfer, with high-speed video capturing swing velocity. Air overpressure was recorded using a seismograph microphone. Rear-only water (tamping) increased beam swing velocity by 69% over the control while confinement with water on both sides increased performance by 12% at a 2:1 water-to-explosive ratio and by 50% at 4:1, though it still underperformed the tamped-only configuration. Pushed water alone did not increase beam momentum and reduced tamping effectiveness by 19% when combined. Seismograph microphone data showed that pushed and low mass confined water configurations produced some of the highest air overpressure levels (up to 139.2 dB), while tamped and control charges produced lower levels (~134–136 dB), suggesting that pushed water may amplify, rather than mitigate, air shock transmission. These findings show that water placement has a strong directional influence on blast dynamics: water behind a charge enhances energy transfer to the target, while water in front provides limited or potentially counterproductive mitigation. This study advances understanding of water–explosive interactions and will lead to more effective charge designs for breaching, disposal, and demolition.

Jan 26, 2026

By T. O. Dauda, L. O. Ojo

One of the results of the Earth summit (The United Nations Conference) on Environment and Development - UNDP is the statement of forest principles. Others include: the Rio Declaration which is that the human beings are entitled to a healthy and productive life in harmony with nature; Agenda 21-for achieving sustainable development in the 21st century; the convention on biological diversity and the frame work convention on climate change. In the preservation of the biological diversity, Government at various levels took series of steps such as legislation, establishment of forest reserves including strict nature reserves, Forest guards, afforestation projects and others. Omo Forest Reserves is one of the Forest reserves owned by the Ogun state Government of Nigeria. It houses the Omo Biosphere Reserve (that is Strict Nature Reserve of International standard). This biosphere reserve is surrounded by buffer zones, which are meant to serves as protection for the biosphere reserves against encroachments. This study showed that the richest plot in term of species composition (that is plot 15 with the species frequency of 123) is almost the least diverse (with Simpson diversity index of 0.9127 which is 0.0238 higher than the least). It could also be established from this study that the diameter size class of trees with the highest frequencies are the lower size classes (5cm-10cm and 10cm -20cm). These results revealed a magnanimous encroachment on the buffer zones, which is an indication of bad status for the Biosphere Reserves as well as against the spirit of the sustainable use of the natural resources.

Jan 1, 2005

By P. Lind, A. Gagnon

"Goldcorp has embarked upon an ambitious, industry-leading, multi-year water use reduction effort. This is a proactive, voluntary effort that reflects our commitment to truly sustainable mining. This effort will focus on increasing water re-use and recycling, and reducing water inputs ultimately towards zero. All of our operating mines are expected to contribute to this effort and are currently in the process of developing plans to meet short and long term objectives. One of the largest needle movers to increase water re-use and recycling is in the area of tailings management. Within five to ten years at Goldcorp, it is envisioned that the need for wet tailings dams will be eliminated and that all new tailings facilities will consist of only filtered or dewatered tailings. Filtered tailings is developing into a mature technology with wide application in mine waste management. This paper describes a conceptual level evaluation on the transition from a slurry to a filtered tailings operation at the Cerro Negro mine in southern Argentina. Key benefits and challenges are highlighted.INTRODUCTION Goldcorp’s Cerro Negro operation is located in the Santa Cruz province in the Patagonian region of Argentina. Cerro Negro has been in operation since 2014 and commercial production was achieved on January 1, 2015. The processing capacity of the plant is 4,000 tonnes of ore per day and in 2016 produced 363,000 ounces of gold and 3.1 million ounces of silver (Goldcorp Inc., 2017). As the mine is located in a semi-arid area, it is important to evaluate technologies that could reduce freshwater consumption and maximize water re-use and recycle rates. The current tailings operation at Cerro Negro incorporates pumping of tailings slurry into a conventionally lined Tailings Storage Facility (TSF). Water is reclaimed from the tailings supernatant pond to the process plant via pumps, however, water losses occur due to evaporation and solution retention within the slurry tailings voids. Converting to a filtered or dewatered tailings operation would allow for increased water recovery prior to tailings disposal, and decreased water losses from evaporation and from retention in the tailings solids void space. This paper describes a conceptual level evaluation on the transition to filtered or dewatered tailings with the primary objective of moving closer Towards Zero Water."

Jan 1, 2017

By M. Fener, S. Kahraman, O. Gunaydin, M. Alber

Falling into the weak rocks category, fault breccias have extremely poor engineering properties. These pebbles typically cause issues with slopes, subterranean construction, and building projects. Professionals will benefit from the creation of some predictive models for fault breccia triaxial strength, as smooth specimen preparation is typically challenging and timeconsuming. The purpose of this study is to develop some predictive models for the differential stress (Δσ) based on physical and textural properties. Artificial neural networks were used to analyse data related to Misis fault breccia. Initially, models with moderate (noticeable, but not good) correlation coefficients were created using multiple regression analysis. After that, the regression models and three distinct artificial neuron network models were contrasted. Regression models are weaker and less trustworthy than artificial neuron network models, as demonstrated by this comparison. Pointed out is the practicality and ease of use of the artificial neuron network model with S-wave velocity and volumetric block proportion. Ultimately, it can be concluded that artificial neuron networks analysis provides a reliable indirect method for predicting the differential stress of Misis fault breccia.

Sep 1, 2025

By J. M. Wempen

As development in underground coal mines progresses away from the critical components of the ventilation system, including the main fans and ventilation shafts, resistance within the system is markedly increased. This results in higher pressure and flow requirements from the main fan(s) to maintain adequate face ventilation. Upgrades to the primary ventilation system are often required. The use of booster fans underground is a potentially practical alternative to the addition of shafts and surface fans. This study presents simulations of the use of booster fans in two underground ventilation scenarios, one longwall and one room-and-pillar. The booster fan effects on the power requirements of the ventilation systems are evaluated.

Jan 1, 2011

By J. M. Wempen

As development in underground coal mines progresses away from the critical components of the ventilation system, including the main fans and ventilation shafts, resistance is markedly increased. This results in higher pressure and flow requirements from the main fan(s) to maintain adequate face ventilation, which often requires that the primary ventilation system is upgraded with additional shafts and surface fans. The use of booster fans underground is a potentially practical alternative. This study presents simulations of the use of booster fans in two underground ventilation scenarios, one longwall and one room and pillar. The booster fan effects on the power requirements of the ventilation systems are evaluated.

Jan 1, 2011

By C. Dorfling, M. Tadie, S. Grobbelaar

The physicochemical properties of the complex electrolytes used in direct copper electrowinning are an important consideration for the development of a high-fidelity model of the process. Direct electrowinning electrolytes typically contain a high background of metallic impurities. The effect of metallic ions on the properties and accompanying change in the limiting-current density for copper reduction have been the subject of several studies. Although various empirical correlations have been published for describing the physicochemical properties of electrowinning electrolytes, the correlations are only applicable to a limited range of conditions and cannot be extrapolated without further validation. Consequently, in this paper we validated existing physicochemical property correlations for the full range of operating conditions applicable to direct copper electrowinning and developed a new correlation for predicting the associated limitingcurrent density for copper deposition. Following, we evaluated the benefit of using the validated correlations as a component of a dynamic electrowinning model.

Jan 1, 2023

By Dalton Fowler

"Pressure vessels used in pressure leaching and pressure oxidation processes in the mining industry are often lined with acid resistant brick and membrane systems. Although the options available when it comes to selecting materials and linings designs for these vessels appear somewhat limited there are, nevertheless? several choices which must be made in order to successfully design, manufacture and construct these linings. These choices require careful evaluation of materials properties which include, among others, thermal conductivity, thermal expansion, chemical swell, and modulus of elasticity, as well as a variety of construction methods.Some of the options available, and some of the means of evaluating them objective of this discussion."

Jan 1, 1999

By J. B. Boisvert, P. Oshust

A significant source of uncertainty in the diamond resource contained in kimberlite pipes is the volume of the pipes. Often the material within a pipe will be mined as ore, leaving the actual geometry of the pipe as a significant source of uncertainty. It is desirable to use stochastic techniques, rather than deterministic methods, to model pipe geometry because stochastic techniques generate multiple realizations that are reproducible and can be used to assess uncertainty in pipe geometry. The proposed methodology uses sequential Gaussian simulation of pierce point locations interpreted from drillholes through a kimberlite pipe. Kimberlite pipes are approximately cylindrical in shape; therefore, the data are transformed to cylindrical coordinates to facilitate the simulation of pipe geometry. Rather than using xyz coordinates to define the pierce points, z, ??and pipe radius are used. The radius variable can be simulated in z-??space to generate multiple realizations of pipe volume. Uncertainty in the volume of the pipe can then be evaluated. This methodology is demonstrated with a kimberlite pipe at BHP Billiton’s Ekati diamond mine.

Jan 1, 2008

By S. K. Oraee

Managers always look for systems with minimum hazards. The hazards create problems for performance of projects. The largest and most important hazards of working underground mine can be related to health, safety and environmental, because if one of these sectors be in hazard, maybe lead to close mine. Failure mode and effects analysis (FMEA) is a widely used quality improvement tool to identify the potential failure modes for measuring reliability of a product or a process. FMEA is performed by developing a risk priority number (RPN), which is the product of severity, occurrence, and detection ratings. On the other hand, with regard to uncertainty in the decision-making, fuzzy theory will be able to model this uncertainty. Fuzzy FMEA provides a tool that can work in a better way with vague concepts and without sufficient information than conventional FMEA. This article by using Fuzzy FMEA and based on HSE criteria evaluate hazards of Parvade No. 1 Mine in Tabas Coal Mine. The results demonstrate the most hazardous parameter is rock burst in this mine.

Jan 1, 2011

By J. P. Rider

The number of extended cut mining systems has increased significantly in coal mines over the last decade, and there is a constant push to extend the face ventilation systems to even greater setback distances. The need to maintain airflow at setback distances of12.2 m (40 ft) and beyond requires that methods for delivering intake air to the face be improved, or alternative ventilation techniques be implemented. The emphasis of this research effort was to examine various techniques to improve the distribution of available air at the mining face in order to reduce face methane levels. A study was conducted comparing the performance of a jet fan, used in conjunction with a machine mounted scrubber, with blowing curtain ventilation in a 27.5 m (90 ft) heading. In addition, a second study was performed on blowing curtain systems examining how scrubber flow, intake air velocity, and curtain setback influence face methane concentrations. Results showed that when the heading advances to a depth of 27.5 m (90 ft) blowing curtain systems were more efficient at diluting face methane levels when compared to a jet fan. Also, increases in scrubber flows and curtain velocity resulted in lower face methane concentrations for blowing curtain systems at 9.2 and 15.2 m (30 and 50 ft) setbacks.

Jan 1, 1997

By J. P. Rider

The number of extended cut mining systems has increased significantly in coal mines over the last decade, and there is a constant push to extend the face ventilation systems to even greater setback distances. The need to maintain airflow at setback distances of 12.2 m (40 ft) and beyond requires that methods for delivering intake air to the face be improved, or alternative ventilation techniques be implemented. The emphasis of this research effort was to examine various techniques to improve the distribution of available air at the mining face in order to reduce face methane levels. A study was conducted comparing the performance of a jet fan, used in conjunction with a machine mounted scrubber, with blowing curtain ventilation in a 27.5 m (90 ft) heading. In addition, a second study was performed on blowing curtain systems examining how scrubber flow, intake air velocity, and curtain setback influence face methane concentrations. Results showed that when the heading advances to a depth of 27.5 m (90 ft) blowing curtain systems were more efficient at diluting face methane levels when compared to a jet fan. Also, increases in scrubber flows and curtain velocity resulted in lower face methane concentrations for blowing curtain systems at 9.2 and 15.2 m (30 and 50 ft) setbacks.

Feb 24, 1997

By Stan Tang, Yiming Sun, S. Amir Reza Beyabanaki, N. Sathi Sathialingam

The Kurve mixed-use development project including a 22-story tower at 2801 Sunset Place was constructed on a site consisting of a roughly rectangular-shaped lot at the intersection of Wilshire Boulevard and Hoover Street in Los Angeles. Two Metro Red Line tunnels, with depths of approximately 30 feet and 58 feet, respectively, cross below the building at distances of approximately 1 foot to over 63 feet from the site. This paper presents numerical modeling performed to evaluate the ground and tunnel behavior in response to building construction. Results of geotechnical instrumentation and monitoring undertaken during the building construction are also discussed.

Jun 13, 2023

By Martin B. Hudson, John Yao, Matthew R. Crow, Yiming Sun, John T. Waggoner, Roozbeh Geraili Mikola

"The Wilshire Grand redevelopment project in downtown Los Angeles includes construction of a new 73-story tower. Construction required excavation up to 93 feet deep (28 m). The south side of the excavation, up to 57 feet deep (17 m), required placement of shoring within about 6 to 10 feet (1.8 to 3.0 m) horizontally away from a 400-foot-long (122 m) section of one of the existing Los Angeles Metro Red Line twin subway tunnels. These tunnels were constructed using a 22-foot-diameter (6.7 m) digger shield, and were initially supported with expanded, precast concrete segments, with final cast-in-place reinforced concrete lining. The temporary shoring system for the deep excavation consisted of soldier piles generally spaced at 8 feet (2.4 m) on center with multiple levels of tieback anchors extending above the subway tunnels. The lowest level of bracing consisted of rakers supporting walers attached to the soldier beams because installation of tieback anchors at that level would conflict with the tunnels. Numerical analyses were performed to predict tunnel movement caused by the excavation and its effects on the train operations. This paper describes the numerical modeling, tunnel and geotechnical instrumentation and monitoring program, and comparison of the computed and observed tunnel responses to the deep excavation and tower construction. With increasing urban redevelopment in major cities, the project is a valuable case history for excavation adjacent to existing tunnels. INTRODUCTION The Wilshire Grand redevelopment project includes the demolition of a 16-story hotel built in the early 1950s and the construction of a new 73-story tower in downtown Los Angeles (LA) that will be the tallest building in the western United States. The project site is situated on approximately 2.7 acres (1.1 Ha) of land bounded by Figueroa Street to the east, Wilshire Boulevard to the north, Francisco Street to the west, and 7th Street to the south (see Figure 1a). The new tower is being constructed by Turner Construction for Hanjin International Corporation. Construction of the basement and foundation of the new tower required excavation up to 93 feet (28 m) deep. Shoring was designed by Cefali & Associates and installed by Malcolm Drilling Company. Along 7th Street, an excavation up to 57 feet (17 m) deep required shoring to be installed within about 6 to 10 feet (1.8 to 3.0 m) horizontally from an existing 400-foot long (122 m) section of one of the LA Metro Red Line subway tunnels (see Figure 1b). The tunnels, extending from the 7th/Metro Station to the Westlake-MacArthur Station, were constructed in the late 1980s and early 1990s with an excavated diameter of approximately 22 feet (6.7 m). They were initially supported with expanded, precast concrete segments with a final cast-in-place reinforced concrete lining. The existing hotel was demolished in 2012 and 2013, with shoring installation and excavation for the new basement occurring as the demolition occurred. At the time of writing, January 2016, the structure of the building adjacent to the tunnels is largely complete."

Jan 1, 2016

By A. McLean, M. Iwase, K. Wakimoto, K. Katogi, Y. Kikuchi

One of the greatest obstacles to the application of physical chemistry principles to the elucidation of slag-metal reactions is a lack of knowledge of activities of the reacting species. To a large extent, oxygen potential of the slag phase governs iron and steelmaking practice. Without oxygen control by means of appropriate sensors, the behaviour of the other elements cannot be managed. In this paper, measurements of the FeO activity with various types of electrochemical FeO sensors will be described together with examples of their applications for improved strategies toward better practice for ladle metallurgy and sulphur and manganese distributions between slag and metal phases during steelmaking. Measurements of FeO activity have also been made in order to improve dephosphorization reactions. This type of work has led to significant reduction in volume of slag generated within the steelmaking vessel, which in turn has important implications for refractory wear, metal yield, alloy recovery and improved productivity. Finally, an on-line sensor is described that permits the oxygen potential to be determined for both the metal phase and the slag phase during steelmaking in the BOF.

Jan 1, 2004

By Robert A. Pimentel

Dust is still a major problem in increasing production from longwall faces. Over the last decade, significant improvements have been made in the development of techniques for reducing dust exposure on conventional and continuous sections. But virtually no improvements have been made in dust control on longwall sections. It is true, that there are many more continuous mining sections than longwall sections in the United States and that the number of workers overexposed on continuous miner sections is much larger than the number on longwall sections. However, the problem on continuous miner sections appears much easier to solve and, in fact, we believe that the techniques are available to get virtually all continuous miner sections in compliance. The problems on longwall sections are much more elusive. Also, the number of longwall sections in the United States is expected to increase during the 1980's. Thus, dust control on longwall sections remains a formidable and important problem. Companies operating longwall sections with a dust problem are faced with the tasks of having to quantify the various dust sources, of selecting proper techniques to reduce the problem, of implementing the techniques and of evaluating their effectiveness.

Jan 1, 1983

By J. Nesset, F. Rosenblum, P. Spira

Sulphide concentrates may exhibit self-heating to various degrees during storage or shipping, the worst cases presenting a serious hazard from fire and SO2 emission. Based on measurements of heating rates on a wide variety of concentrate samples in a special apparatus, combined with field experience, a methodology has been developed which allows concentrates to be rated for their heating potential. This has proven to be very useful in practice, for example, in deciding on the need to take preventive measures. Oxidation under ambient conditions in the presence of moisture initiates heating locally within a stockpile. In the case of highly active materials, such as those that contain abundant pyrrhotite, heating may progress through three stages to temperatures well above 500°C. However, most concentrates show little or no propensity to self-heat. Heating rates were used to estimate values of the heat output, or self-heating capacity (in joules per gram), which sustains the process at each stage. Thermal data from differential scanning calorimetry are also reported. Variables which affect self-heating are discussed and an actual case of heating control on a stockpile by covering is described. A simple apparatus which can be used to simulate stockpiling conditions has been tested successfully and is proposed as a convenient test system.

Jan 1, 2001

By J. Nesset, F. Rosenblum, P. Spira

"Sulphide concentrates may exhibit self-heating to various degrees during storage or shipping, the worst cases presenting a serious hazard from fire and SO2 emission. Based on measurements of heating rates on a wide variety of concentrate samples in a special apparatus, combined with field experience, a methodology has been developed which allows concentrates to be rated for their heating potential. This has proven to be very useful in practice, for example, in deciding on the need to take preventive measures. Oxidation under ambient conditions in the presence of moisture initiates heating locally within a stockpile. In the case of highly active materials, such as those that contain abundant pyrrhotite, heating may progress through three stages to temperatures well above 5000C. However, most concentrates show little or no propensity to selfheat. Heating rates were used to estimate values of the heat output, or self-heating capacity (in joules per gram), which sustains the process at each stage. Thermal data from differential scanning calorimetry are also reported. Variables which affect self-heating are discussed and an actual case of heating control on a stockpile by covering is described. A simple apparatus which can be used to simulate stockpiling conditions has been tested successfully and is proposed as a convenient test system.INTRODUCTIONPrevious publications from this laboratory on the evaluation of self-heating in sulphides dealt with tailings backfill (Rosenblum et al. 1982) and waste rock (Rosenblum and Spira 1995). Sulphide concentrates may likewise exhibit self-heating in storage or during shipping. In a comprehensive but dated review, Kirshenbaum (1 968) pointed out the conflicting nature of information on means of controlling the problem, particularly with regard to the application of water and ventilation. Modelling by Simpson (1 97 1) of autogenous heating in stockpiled zinclead concentrate and associated field measurements by Wright et al. (1972) showed that the supply of oxygen by wind and the shape of the piles were the major factors in the development of hot spots. Simpson did not attempt to explain the complex mechanism of self-heating, simply ascribing its onset to oxidation. Pearse (1 980) investigated a potential method of testing for selfheating which consisted of (i) reaction with hydrogen peroxide and (ii) differential thermal anal sis, to characterize the response of concentrates at both ambient and temperatures above 100 C. He found the method sensitive enough to identify the need for careful handling but not to predict ignition. He recommended compacting concentrates and covering stockpiles with plastic sheeting to prevent ingress of air. All these workers recognized the key role played by oxygen and moisture in triggering self-heating."

Jan 1, 2001

By Mike Amick

As virgin coal reserves dwindle, more and more mines are being opened in areas with previous mining. As addressed in this conference before, there are solutions available for designing mines extracting coal from reserves with known underground workings above or below the target seam. Often times, however, mining begins with limited knowledge of the underground workings. Even with careful planning, the proposed design has limited success because the ?facts? as presented during planning turn out not to be as accurate as one would like. At National Coal?s Mine #14, mining the Walnut Mountain seam, after driving the main entries in some 34 crosscuts, it was found during routine mine examinations that the pillars had separated from the roof in a few areas of the mains. Immediate roof conditions proved to be sound but questions arose concerning the stability of the main roof and floor. Core tests were done to better determine the rock strengths and characteristics. The paper presents the ideology used to tackle the effects of mining over old works in an operating coal mine. This paper discusses the analysis of the symptoms observed and the steps taken to ensure that this pillar separation was caused by the underlying old workings and that the separation was expected and controllable.

Jan 1, 2009

By Mike Amick

As virgin coal reserves dwindle, more and more mines are being opened in areas with previous mining. As addressed in this conference before, there are solutions available for designing mines extracting coal from reserves with known underground workings above or below the target seam. Often times, however, mining begins with limited knowledge of the underground workings. Even with careful planning, the proposed design has limited success because the ?facts? as presented during planning turn out not to be as accurate as one would like. At National Coal?s Mine #14, mining the Walnut Mountain seam, after driving the main entries in some 34 crosscuts, it was found during routine mine examinations that the pillars had separated from the roof in a few areas of the mains. Immediate roof conditions proved to be sound but questions arose concerning the stability of the main roof and floor. Core tests were done to better determine the rock strengths and characteristics. The paper presents the ideology used to tackle the effects of mining over old works in an operating coal mine. This paper discusses the analysis of the symptoms observed and the steps taken to ensure that this pillar separation was caused by the underlying old workings and that the separation was expected and controllable.

Jan 1, 2009