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By D. F. Doerr, E. Blalock, D. R. Bush, K. D. Cohen

"BACKGROUND The design, development, fabrication, and test of a cryogenic supply for a refuge alternative is part of a larger effort funded by the National Institute for Occupational Safety and Health and managed through a Space Act Agreement with the National Aeronautics and Space Administration at the Kennedy Space Center, FL to create cryogenically based life support equipment responsive to the needs of miners as required by the Miner Act of 2008. This work is done by a joint contractor/NASA team. In particular, the Cryogenic Refuge Alternative Supply System (CryoRASS) serves to provide a respirable air source to miners confined for 96 hours in a mine refuge alternative. This system stores liquid air in a zero-loss cryogenic reservoir (Dewar) until an emergency requires use. The system does not require electric power when in use by miners. Because of the very cold nature of the liquid air, considerable heat stress relief and reduction of humidity is provided in addition to the required replenishment of oxygen. Moderate dilution of CO2 also occurs.INTRODUCTION The design of this new cryogenic refuge alternative supply system (CryoRASS) uses NASA/Kennedy Space Center technology as a development baseline. The design stores cryogenic (liquid) air that is warmed in an air handler box and the resulting gaseous air is introduced to the chamber that not only causes air circulation, but relies upon environmental and human heat to expand the liquid air to a gaseous state. Therefore, the primary benefits of the liquid air source, besides atmosphere maintenance (oxygen), is refuge cooling and dehumidification. This results in reduction of human heat stress and this occurs without the need for electrical power in the refuge chamber. This reduction is a major factor in ""apparent heat"" and the human perception of comfort. Another benefit with introduction of ""air"" vs only ""oxygen"" is the dilution of carbon dioxide. The volume of new air will displace existing refuge air and this air laden with humidity/CO2/low O2 passes out of the refuge relief valves. These RVs should be strategically placed to vent stagnant air preferentially. An initial system test was conducted in our Florida facility in a production 10-person hard chamber for 96 hours. Last year (2014) the system was tested with a 23 person inflatable refuge alternative in Bruceton. For this test, the CryoRASS air handler was redesigned to offer superior characteristics when installed in a Built-in-Place refuge alternative. This report describes the results of the modified system being tested in the Pittsburgh Experimental Mine while attached to a 30 person refuge for 96 (+/-) hours."

Jan 1, 2016

By Phillip R. Moyle

Voluminous deposits of commercial-grade phosphate occur in sedimentary strata in a 350,000 km2 (135,000 mi2) area of the middle Rocky Mountains of North America known as the Western Phosphate Field. The Permian marine strata that host the phosphate were deposited on the western margin of the North American craton and subsequently deformed, first by folding and thrust faulting of the Laramide orogeny, and then by Cenozoic Basin and Range block faulting. Carbonate fluorapatite is the primary phosphorus-bearing mineral. Organic matter is abundant in some strata, and both biogenic and non-biogenic pyrite are also present. Certain strata are enriched in several trace elements, especially in arsenic (As), cadmium (Cd), chromium (Cr), copper (Cu), molybdenum (Mo), selenium (Se), vanadium (V), uranium (U), and zinc (Zn). Phosphate has been mined from the Western Phosphate Field for nearly 100 years. Phosphate mining and processing constitutes the largest mineral industry of Idaho, producing more than $600 million in processed mineral value in 1997. Resource management agencies, phosphate producers, and others are concerned about the release of Se from phosphate mine wastes, especially at Maybe Canyon, and the potential effects that Se and other trace elements may have on the environment and on human health. U.S. Geological Survey (USGS) Mineral Resources Team scientists initiated a multidisciplinary study of the Permian Phosphoria Formation and related rocks in the south- eastern Idaho sector of the Western Phosphate Field in response to a request by the U.S. Bureau of Land Management (BLM). Studies to date reveal that Se is present in several phases, including native Se, and in an as yet unidentified form, possibly an organo-Se compound. Selenium is also present in pyrite and sphalerite. Selenium concentrations range from 1.2 to greater than 1,000 parts per million (ppm) in samples collected from exposures of the Meade Peak Phosphatic Shale Member of the Phosphoria Formation (Meade Peake) at Enoch Valley. The results suggest that Se concentrations vary spatially across strata and with depth, perhaps comparable to spatial variations of phosphate and organic carbon concentrations throughout the Western Phosphate Field demonstrated in previous studies. Some Se-enriched strata may be of adequate dimension to allow selective extraction during mining. Such units could be handled separately from the main ore process or waste streams and isolated in order to reduce the potential for release of Se to the environment

Jan 1, 2001

By D. J. Hutchinson, S. Nickson

Cable bolts are used as a means of rock support around underground excavations in many mines across Canada and around the world. A substantial body of research on cable bolting was conducted at a number of Canadian universities and mines from the mid-1980s through the 1990s. Since then, research into selected areas of cable bolting practice has continued in Canada. The research has focussed on cable bolt instrumentation and on the inclusion of cable bolts in empirical stope design techniques. A review of cable bolting practice is now warranted at many mines. It has been five years since the completion of the previous substantial body of Canadian academic research and the associated advancement in understanding of cable bolt design, implementation and verification practice. Attempts were made at that time to transfer the new design procedures and performance assessment technologies to mine-site personnel. In some cases, this was effective, and ground control personnel continue to improve on their cable bolting practice at each specific mine site. However, at other sites, experienced people have moved on, and the new, less experienced personnel do not have access to the training or technical resources required to improve their understanding of the subject. In other cases, the technology was not transferred effectively to practitioners, with the result that substantial improvements can be made to the cable bolting practice at those mines. Guidelines for auditing cable bolting practice are provided in this paper. The guidelines include a discussion of the objectives of the audit, suggestions for audit procedure and a summary of the possible outcomes of a cable bolt audit. The objectives of an audit might include assessing the reasons for unexpected cable bolt failures, evaluating the quality of the installation procedures, quantifying the efficiency of the cable bolt system and assessing training requirements and procedures. A cable bolt audit should include consideration of all aspects of the cable bolting cycle, including the design, implementation and verification phases of the operation. At the end of the audit, a ranking should be assigned to the components of the cycle. The ranking system can then be used to identify items that require immediate attention, others that could be improved and others that are adequate. Following completion of a cable bolt audit, increased confidence in the support system and its application is generally, found, along with the potential for cost savings in many cases.

Jan 1, 2002

By Bahne C. Cornilsen, X. Shan, David H. Carlson, John H. Johnson

The air in three U.S. underground coal mines has been sampled. The data developed show the relative importance of the various pollutants and quantify the need for control. Total respirable particulate matter (TRPM) was found to be the critical pollutant (the one requiring the most dilution for control). TRPM is considered to be "respirable coal dust" by procedures approved for sampling in U.S. underground coal mines. However, this "respirable coal dust" also includes diesel particulate matter (DPM) and particulate from other sources. While "respirable coal dust" was the critical pollutant, Raman spectroscopic analysis showed that more than half of this "respirable coal dust" was DPM. The DPM in the samples ranged from 22 to 152% of the 2 mg/m3 limit for respirable coal dust. Thus DPM was the critical pollutant using the 2 mg/m3 respirable coal dust limit. SO2 gas produced by the combustion of diesel fuel containing sulfur was the second-most critical pollutant. Characteristic curve slope (CCS) values were calculated to determine the quantitites of the various pollutants generated per unit of diesel haulage activity. Mine 1 had the highest TRPM CCS values with 29 mg/m3/%C02 for the Ramcar and 57 mg/m3/%C02 for the Haulageway location. The highest coal particulate CCS measured was 30 mg/m3/%CO2 and the highest diesel particulate CCS measured was 27 mg/m3/ %C02. Both of these high values were measured in the Mine 1 haulageway location. Calculations were made to determine the controlling CO2 concentrations (CCC) at which all other measured pollutants would be within their limits. These CCC values, which, for the mines sampled, were based on TRPM, varied from a low of about 0.07% for the Mine 1 haulageway location, to a high of about 0.15% for the Mine 2 Ramcar and haulageway locations. Weekly average CO2 concentrations measured in these mines ranged from 0.09 to 0.11 % for the Ramcar, from 0.05 to 0.09% for the haulageway, and from 0.08 to 0.11 % for the return. The concentrations of TRPM ranged from 1 and 2 mg/m3 in mine areas frequented by personnel, and to greater than 4 mg/m3 in returns where personnel are not exposed.

Jan 1, 1991

By M. Li, J. K. Thompson, A. S. Azman

"Powerful mining systems typically generate high-level noise that can damage the hearing ability of miners. Engineering noise controls are the most desirable and effective control for overexposure to noise. However, the effects of these noise controls on the actual hearing status of workers are not easily measured. A tool that can provide guidance in assigning workers to jobs based on the noise levels to which they will be exposed is highly desirable. Therefore, the Office of Mine Safety and Health Research (OMSHR) of the National Institute for Occupational Safety and Health (NIOSH) developed a useful tool to estimate the hearing loss due to occupational noise exposure in a systematic way and evaluate the effectiveness of developed engineering controls. This computer program is based on the ISO 1999 standard and can be used to estimate the loss of hearing ability caused by occupational noise exposures. In this paper, the functionalities of this software are discussed and several case studies related to mining machinery are presented to demonstrate the functionalities of this software. INTRODUCTIONPeople regularly exposed to noise can develop hearing loss at different levels of severity depending on a number of factors. The resultant hearing loss can affect one’s ability to understand speech, learning, acoustic signal perception, or appreciation of music. Hearing loss caused by overexposure to noise has long been recognized in literature. However, it still does not get serious attention by those working in noisy environments because the loss of hearing ability is a gradual process and workers are often unaware until the damage becomes an apparent problem. In the United States, occupational hearing loss is one of the most common work-related illnesses. Depending on the definition of exposure and impairment, in 2012 the National Institute for Occupational Safety and Health (NIOSH) estimated that there are between 5 and 30 million workers in the U.S. who are exposed to noise levels at work that put them at risk of hearing loss.4 In the mining industry, noise-induced hearing loss (NIHL) is particularly severe due to the fact that heavy-duty machinery is widely used to improve production efficiency, and this machinery can generate much higher-level noise than the permissible level defined by regulation. As a result, the mining sector has the highest prevalence of hazardous workplace with high noise exposures (76%) among all industrial sectors."

Jan 1, 2015

By François Martin, Roland Plassart, François Laigle

"MOTIVATION The storage of nuclear waste gives rise to a lot of innovative issues for underground space technologies. The nuclear activity of waste generates temperature effects on both the lining and the surrounding rock mass. In order to avoid these unfavorable effects, the number of waste containers is controlled in the gallery section. The galleries section has consequently ranged from a diameter of 4 to 6 meters. However, in the case of intermediate-level nuclear waste, due to the lower temperature, the number of containers in a cross section of a gallery is assumed to be safely increased. Despite technical difficulties, a large diameter gallery (typically 12m excavated) seems to be more cost effective. This paper demonstrate the feasibility of such a gallery in the specific context of CIGEO (French Geological Repository Project for nuclear waste), located in the Bure area in the north-eastern of France. The geology of Bure at the project’s depth (about 520 meters) consists in a quite homogeneous layer of Callovo-Oxfordian argillites (COx argillites). With such an overburden, this rock is known to have a high plastic behavior with significant time-dependent effects. These mechanical properties require complex behavior laws in computational modeling used for the design of underground facilities.EXPERIENCE OF LARGE DIAMETER GALLERIES In order to identify some specificities in the design of such openings, a research has been run on existing galleries of large diameter (more than 10 meters), like the tunnel of Chamoise, Lötschberg, Tartaiguille or Saint-Martin-La-Porte. Two of these representative examples are detailed hereafter. Tunnel of Chamoise (French Jura) In spite of a lighter overburden (400m versus 520m), an anisotropic initial stress state and a variable rate of carbonates, the highway tunnel of Chamoise is quite similar to the planned gallery for intermediate-level nuclear waste, with a geology very close to the CIGEO’s one in some sections. Because the northern tube encountered difficulties during the excavation a few years before (several over-excavations and spalling, especially in the bench), the excavation of the southern tube has been carried out in two steps, but with a high bench and a small curved invert (Figure 1). The design of the immediate support consists in long bolts and a shotcrete layer. The concrete lining is about 50cm thick."

Jan 1, 2016

By Cary Hirner, Dan Lopez, Ross Webb, Stephen O’Connell

"Construction of the largest desalinization plant in the Americas has commenced in northern Chile. It is part of a several billion dollar expansion at a copper mine whose operations nearly stopped due to the challenge of securing a reliable source of water from the Pacific Ocean in a safe and environmentally sound manner. This paper discusses the risk management, design and construction of a quadruple chamber intake and outfall shaft, high capacity pump station, three 7m diameter vertically drilled marine shafts and three subsea tunnels constructed through challenging Andean hard-rock geology. The three 2.5m diameter subsea microtunnels are being mined with vertical curves through variable quality rock 30 meters beneath the ocean and retrieved in the wet from the 7m diameter marine shafts. INTRODUCTION AND BACKGROUND The battle for securing the rights to a constant water supply is a worldwide issue and nowhere is that more evident than the Atacama Desert of Chile, the world’s driest place with areas of the desert that have not seen rainfall in recorded history. The Atacama Desert also happens to be home to some of the world’s largest ore deposits which require huge amounts of water to extract and process. What available water there is comes from three main sources: deep seated wells, glacial water from the Andes Mountains, and desalinated water. Vying for water from wells and glacial streams and lakes are numerous agricultural and domestic facilities in the valleys surrounding the Atacama Desert. Environmental regulations and legal rulings have limited the amount of “natural” source water which can be used for mining purposes. Desalination plants are a known solution for combating water scarcity, albeit a costly one. The total estimated cost of constructing this desalination plant is over $3B USD, which will include a 2500lps capacity and an approximately 118km pipeline from the coast up to the mine located in the Andes. The overall scope of the project includes design, procurement, and construction packages for the 2500lps desalination plant including the seawater reverse osmosis plant, water conveyance to the mine, power transmission, the reservoir and the marine works package which forms the basis of this paper. Key components of the underground construction portion of the Marine Works are:"

Jan 1, 2016

By J. Kretschmann, P. Goerke-Mallet, C. Melchers

Mining always leaves a mark behind. Dealing with this legacy is not only a tremendous challenge in Germany, but internationally too. The Technical University Georg Agricola (THGA) in Bochum, Germany, has established a Research Center for Post-Mining. Researchers combine expertise from a variety of technical and nontechnical fields in their quest to shape the post-mining era that completes the mine life cycle. In this respect, the Research Center focuses on four research areas: Perpetual tasks and mine water management, Geomonitoring, Material sciences and site transition. With more than 200 years of successful partnership with the mining industry in Germany and abroad, THGA offers a perfect setting for fresh and sound ideas in order support mining’s social license to operate. The aim of the paper is to describe the Post-Mining Research Center along with exemplary research projects that are of interest to the mining industry globally and to foster technical communication and research networking.

Mar 2, 2022

By N. Prenn

"INTRODUCTION The 2014 SME Guide for Reporting Exploration Results, Mineral Resources, and Mineral Reserves (the SME Guide) has been adopted by the Society for Mining, Metallurgy, and Exploration, Inc. (SME). The SME Guide is recommended as a minimum standard and a basis for developing industry best practices in the classification of Mineral Resources and Mineral Reserves for public and private purposes. The Guide is therefore strongly recommended to be used by members of this organization. The SME Guide was updated in 2014 to include CRIRSCO (Committee for Mineral Reserve International Standards) core definitions, and it is envisioned that the U. S. Securities and Exchange Commission (SEC) will adopt the SME Guide in 2016. However, as of the end of 2015, the SEC Industry Guide 7 remains the standard for the U.S. reporting of Mineral Reserves. This paper will cover the classification of Mineral Resources and Reserves, a discussion of Modifying Factors, and the classification definitions and guidelines. The definitions and guidelines contained in this report are from the SME Guide. FRAMEWORK FOR MINERAL RESOURCE AND MINERAL RESERVE CLASSIFICATION Figure 1 illustrates the classification of Mineral Resources and Mineral Reserves using the Guide. Mineral Resources are divided into three classifications of Inferred, Indicated, or Measured while Mineral Reserves include Probable and Proven classifications. These classifications reflect improved knowledge and confidence of the deposit from the top of the figure to the bottom. In other terms, the deposit risk also decreases from top to bottom.The relationships in Figure 1 reflect different levels of geoscientific knowledge and different degrees of technical and economic evaluation. Mineral Resources can be estimated on the basis of geoscientific information with input from other disciplines to establish reasonable prospects for eventual economic extraction. It was not too many years ago that the classification of a Mineral Resource was based on the evaluation of a limited set of factors that included spatial drill hole and grade distribution (kriging variance, as example), distance to the closest hole, and number of samples used to estimate a block grade. These are still important considerations, but classification following the Guide must also take into account sample integrity, sample QAQC, database integrity and completeness, geological understanding, and geological and grade or quality continuity. In addition, a general consideration of the Modifying Factors, to establish reasonable prospects for eventual economic extraction, adds complexity to the classification."

Jan 1, 2016

By S. Hearn, S. Boskovic, A. Smethurst

"The digestion of minerals in strong acids or at elevated temperatures can result in the release of large amounts of silicic acid which can polymerize in solution to form colloidal silica and gels. Colloidal silica can cause a number of problems including interfering with flocculation, initiating crud formation in solvent extraction (SX), decreasing SX extraction kinetics and increasing SX phase disengagement times. Huntsman’s POLYSIL® polyether coagulants have a “lock and key” relationship with the surface of colloidal silica to help lower the concentration of these particles in solution, improve process efficiency and reduce reagent losses by minimizing crud formation. This paper investigates some of the issues caused by colloidal silica in hydrometallurgy processes and illustrates how the use of POLYSIL® coagulants has helped to improve process outcomes. INTRODUCTION Coagulation differs from flocculation in a number of ways. Coagulants are relatively small molecules that modify the surfaces of fine particles, weakening repulsive forces between them and allowing particles to stick together, while flocculants are generally molecules that are large enough to bridge the boundary layers between the particles. With flocculation, addition rate and mixing all make a difference to the flocs formed. Coagulation, on the other hand, is an equilibrium process. With coagulation it is only necessary to achieve good mixing, and coagulates will form as Brownian motion pushes the particles into each other. In real systems, this process is complete within seconds. Huntsman’s POLYSIL® polyether based coagulants have a strong affinity with the surface of colloidal silica formed by the polymerization of silicic acid. While silica found in minerals has a low aqueous solubility, large amounts of silica as silicic acid can be released as these minerals are digested in strong acids at elevated temperatures. The solubility of free silicic acid is about 150 ppm under pH conditions typical in acid leach environments (1), so the bulk of the silica will polymerize in solution to form colloidal silica. Colloidal silica can pass through a hydrometallurgy process without affecting any of the operations. However, it can cause a number of problems. These include gelling in a leach, interfering with flocculation or crystallization, initiating crud formation (2,3,4), decreasing extraction kinetics and increasing phase disengagement times (5,6) in solvent extraction. In these cases, coagulating the silica with POLYSIL® coagulants can reduce or eliminate the problem by enabling these particles to be flocculated and removed from the solution."

Jan 1, 2015

By T. A. Laser

"INTRODUCTION A positive workplace environmental, health, and safety (EHS) culture affords organizations and corporations many benefits, including increased trust and employee morale, sustainable EHS performance improvements, and reliable productivity and profit margin growth. Unfortunately, many leaders and EHS professionals struggle daily to achieve and maintain positive workplace cultures and consistent business results. While lack of management support, corporate or employee buy-in, resources, and time are common factors that conflict with an EHS culture and safe work behaviors and processes, there are many other actions that threaten the positive attributes of an organization’s culture. Often these culture killers are not recognized, or worse yet, ignored because they are considered taboo. For example, voicing observations or questioning long-held management practices or process that were initially designed to promote EHS values, but no longer do so. Unfortunately, this could be viewed as challenging authority, not being a team player or even not valuing EHS. And for those that speak up, the potential for negative consequences can be real impediments to positive change. Having an open mind, constantly striving to identify culture killers, and putting forth the effort to eliminate them are the first steps to begin reaping the benefits of having a sound workplace culture. This paper helps readers to: • Recognize culture killers that negatively impact fostering and maintaining sustainable EHS cultures in the workplace. • Understand how to prevent, avoid, and respond to culture killers, before they wreak havoc in your organization. • Assess EHS culture strength, and implement plans to continuously improve it. The desire to draw boundaries around concepts, put things into boxes, and nail down requirements for something that is virtually impossible to solidify for any length of time is quite fascinating! These desires can pose challenges when trying to define what the perfect EHS culture should look like. The very act of trying to define our culture tends to create silos, and these silos, in turn, can become “culture killers”. The following is one of the most common culture killers. UNBALANCED ORGANIZATIONS TRIGGER CULTURE KILLERS Unbalanced organizations occur when an organization’s constantly shifting focus forces other important needs to take a back seat--until the focus changes again. This balancing act can be detrimental and lead to catastrophic results including low morale, lack of trust, employee dissatisfaction, high turnover, increased incidents, poor profit margins, loss of market share, and ultimately into organization-wide failure."

Jan 1, 2018

By Sergio Flores, Nate Long, William Hodder, Phil Rhodes, Tim McQueary

The Surface Water Supply Project Segment B3 is a 4 miles section of tunnel that will run East- West in Houston TX, from Hopper St to I-45. The tunnel will be mined by using a 128" Dia refurbished 1987 Lovat Tunnel Boring Machine capable of operating in Open or EPB mode. The tunnel will be temporarily supported with ribs and lagging and a 96" Dia pipe will be grouted into place. All four miles of this project are within Petroleum Pipeline Easements. The project includes seven shafts, 2000' of tunnel in potentially petroleum contaminated ground, crossing the Hardy Toll d, I-45, the nion Pacic ailroad ight of Way and multiple oil and gas pipeline crossings. This paper summarizes the planning and drive performed to date.

Jun 23, 2024

By Rainer Antretter

The city of Garmisch-Partenkirchen in southern Germany is located at a main transit road to Tyrol in Austria and suffers of a very heavy traffic load. Therefore, the Kramertunnel as a by-pass tunnel is built to release/mitigate the traffic through the city centre. The 3,600 m long single tube road tunnel is designed with a parallel but smaller emergency tunnel and with cross passages, fitted with single- and doublesided emergency bays, a vent shaft, and an intermediate ceiling to separate fresh air supply from the road traffic. The tunnel, concrete lined along its entire length provided the challenge to find smart formwork solutions for quick set-up, repositioning, setup and pouring. Three particularly specific sections are discussed in this paper.

Jun 13, 2023

By X. Song, Q. Zhang

"The development of fracture zones in surrounding rock mass has significant impact on the stability of underground mine roadways. Detection of the fracture zones is of compelling importance for maintaining roadway stability as well as for safe and speedy excavation of the roadways. This paper presents a study conducted at Dong Bao Wei underground coal mine, where the roadways were developed in diabase rock mass. The roadways suffered severe damages, including sloughing and excessive floor heaving. The borehole imaging technique was applied in the study to observe and detect fracture zone development surrounding the roadway openings. Based on the borehole imaging studies, new roadway support systems were proposed to improve the stability. INTRODUCTION At the Dong Bao Wei Coal Mine three main roadways of the west wing were excavated. The three roadways had semicircle arch cross sections and were at a depth of 650 meters, each being about 750 meters in length. The roadways were driven through a section of thick diabase intrusion, which was softened by water with reduced strength and may turn into powder form under weathering. Site investigation indicated that the roadways in diabase intrusion zone were badly damaged due to severe deformation, and very serious roadway sidewall sloughing and spalling accompanied by severe floor heave often occurred.(Figures 1 and 2) In order to ensure the normal use of the roadway, undercuts were excavated. However, this operation seriously affected the roadway construction progress and increased the amount of roadway support operations as well as the roadway maintenance costs. Furthermore, a roof fall accident occurred in nearby drilling site. The investigation indicated insufficient support provided for the roadways which imposed significant safety hazards and would have serious impact to mining production and subsequent mining activities.The support of the main roadways is a critical task and is the focus of the underground opening excavation work at the mine, since more than 40 years of service life is required from these main roadways. For these roadways, large cross sections with high degree of stability and minimal amount of deformation should be maintained. Therefore, providing sufficient and appropriate roadway supports is of significant importance to the coal mine. In this paper, in order to optimize the roadway supporting system, studies were carried out on the geological structures, lithological characters, roof bolt anchoring features and suitable anchoring layers. The studies were aimed at ensuring the stability of mine roadways, reducing the roadway maintenance costs and providing a safe mine passageway for orderly production and progressive development of the mine"

Jan 1, 2016

By J. Rostami, P. P. Nelson, A. Khetwaln

Tunnel boring machines (TBMs) can be considered as the method of choice for tunneling in many projects due to the high level of efficiency and high potential productivity, safety, and applicability in a variety of subsurface conditions. The muck transportation system in a TBM tunneling operation plays a significant role in the process and impacts the overall performance of the machine. This paper introduces a recently developed method of simulating TBM operation through discrete event simulation (DES), which allows for tracking of the various activities, incurred downtimes in the operations, and overall machine utilization. The study presented here compares two different muck transportation systems, conveyor and rail, under similar geological conditions to quantify the impacts of the choice of muck transportation systems on machine utilization. The results show the applicability and extent of redundancy in the use of the two systems relative to machine capabilities and their sensitivity to geological conditions.

Jun 13, 2021

By Marcel Michaud

Over the past five years, the two-fold growth in Canada's coal industry "Figure, 1" results primarily from the coking coal market to Japan and, to a lesser degree, by the increasing use of sub-bituminous and lignite coal for power generation in the Prairie Provinces. This expansion will continue, but production of coal for domestic thermal generation of electricity will grow at a faster rate than coking coal exports "Figure, 2". Half of the 20 million tons of thermal coal used for electrical power generation in Canada during 1974 were imported by Ontario Hydro from U.S. coal companies in West Virginia and Pennsylvania. Ontario Hydro's Nanticoke station on Lake Erie which will consume 7.5 million tons of coal in 1977 when fully operative, as well as other future planned projects, could cause Ontario Hydro's coal consumption to rise from 10 million tons today to 20 to 25 million tons by 1985

Jan 1, 1975

By Jerry F. Fountain

Variations in ore grade, mineralogy, and copper pricing structures over the life of the Inspiration mine have mandated many modifications to the treatment methods to maximize process economics. In the 1970's, copper prices generally declined, while inflation, wages, and interest rates increased. A metallurgical treatment route had to be developed for this continuing economic climate which would be capable of minimizing labor, energy, and capital cost requirements. After many years of development, the patented "Ferric Cure" process was introduced to satisfy these requirements. This dump leach process for treatment of mixed oxide/sulfide ore includes: strict mineralogical control of ore placed for leaching, controlled leach pad construction, solution saturation and curing of the pads with higher acid concentrations, and, finally, rinsing of the cured pads for removal of dissolved copper. Leach solutions, high in sulfuric acid during the cure application and low in sulfuric acid during the rinse, contain sufficient ferric iron to enhance the leaching of chalcocitic sulfide minerals.

Jan 1, 1983

By Robert W. Cope

"Mining began, in the Colstrip area in the 1920's by the Northern Pacific Railroad. The coal was used for steam locomotives until 1957, when the advent of diesel power made them obsolete. In 1959, Montana Power Company purchased the Northern Pacific properties including the mining equipment, coal leases and the town of Colstrip. Western Energy Company, a wholly owned subsidiary of Montana Power Company was formed in 1966 to manage the mining operations in Colstrip. The Rosebud Mine officially re-opened in 1968 to supply coal for Montana Power Company's J. E. Corette Plant In Billings. Since 1970, Long Construction has operated the mine equipment for Western Energy Company". The Rosebud Mine is located in Southeast Montana and supplies coal to two 350 megawatt power plants located in Colstrip and one 180 megawatt plant located in Billings. Approximately 30 percent of Western's annual production is consumed by these plants. The remaining production is shipped to the mid-west and burned by utility companies and municipalities.

Jan 1, 1981

By H. R. Quina

Phosphate is one of the most important minerals in our world today. It contains the life-giving element of phosphorus, which is essential to the growth of every living cell in plant, animal, and man. This vital mineral is found in twenty-three states of the United States; however, for more than 70 years, Florida has led the nation in phosphate-production and now produces 70% of the requirements of this country. Since the early 1880% when rich phosphate deposits were accidentally discovered in a river-bed in Central Florida, the industry has developed into a multi-million-dollar operation. Phosphate mining began in Florida in 1887 with very crude methods and equipment. The original process was necessarily slow and tedious, resulting in total production of 3000 tons in 1888. Progress was made in improved mining operations, and by 1894. Florida had grabbed the lead as the nation?s largest phosphate-producing area, and is still in the top position.

Jan 1, 1962

By Robert W. Gordon

The art of excavating tunnels with continuous, full-face boring machines began almost 90 years ago, in the early 1880's. At this time, Colonel Beaumont designed and manufactured a seven-foot diameter tunneler for boring under the English Channel, Despite the absence of modern materials and manufacturing techniques, Beaumont's tunneler, powered by compressed air piped in from the surface, was quite successful. During its short, but impressive existence, this machine set a record of advancing in chalk 50 feet per day for 53 days - which is impressive even by today's standards. Despite the apparent success of this early tunneler, almost 80 years passed before any further significant development was accomplished in this field. Demands from the construction and mining industry and society itself have motivated the development of the modern tunneling machine. Our rapidly growing civilization needs faster, less expensive and safer means of excavating tunnels. Space age technology and materials have played a major role in making hardrock tunneling machines possible.

Jan 1, 1970