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By F. Calizaya

The Western Mining Training and Translation Center is a consortium of four universities devoted to developing educational and training projects to reduce the incidence/accident rates in the mining industry. The center consists of Missouri University of Science and Technology, Montana Tech, the Colorado School of Mines and the University of Utah. It is fully funded by the National Institute for Occupational Safety and Health (NIOSH). The center manages 15 educational projects and one translation project. Hazard Identification and Risk Assessment (HIRA) for Small Mines is an educational project managed by the University of Utah. The objectives of this project are to identify critical mine hazards, assess risks; outline procedures to reduce accident/incident rates in small mines in the western United States and to train mine workers and super-visors on HIRA in each participating mine. To accomplish these objectives, the HIRA personnel visited 15 small mines in Utah, Colorado, Nevada and California. At these mines, most operators were employing independent contractors to perform several tasks ranging from drilling, blasting and mucking of rock at the work site to hauling ore to a processing plant. The operation of diesel-powered equipment was one of the major tasks performed by the contractors. This article presents three case studies in which contract workers performed a number of tasks with no reportable incidents but did so unsafely. It also highlights the training received by most contractors, the constraints imposed upon them and the safety hazards to which they are exposed most frequently.

Jan 1, 2008

By W. E. Coughlin, R. L. Faverty, F. H. Lightner

Introduction The intent of this paper is to present the general strategy and method of implementation to achieve a "fast-track" mine development. The major objectives of a "fast-track" or rapid development schedule are to minimize front-end development expenditures and to realize an early cash flow from operations. The Borealis project of Houston International Minerals Corp. (HIMCO) is used as the working example to illustrate the development schedule. Borealis is a 2.3 kt/d (2,500 stpd) gold-silver heap leach operation near Hawthorne, NV, Pre-Feasibility Planning Proper early planning and identification of priority items were necessary to expedite project progress. On April 1, 1978, HIMCO leased the rights to the Borealis prospect and initiated exploration activities almost immediately. Since Borealis was showing excellent potential for mine development, an effort to clear the way environmentally was initiated during the summer of 1979. With the Borealis properties located within the Toiyabe National Forest, the US Forest Service (USFS) was recognized as the "lead" or respon¬sible agency for addressing the environmental issues. Early scoping of the environmental issues by both HIMCO and the USFS allowed HIMCO to take the initiative and address two potentially critical issues-archaeological and biological. Third party consultants, agreed upon by HIMCO and the USFS, were contracted to conduct archaeological and biological surveys. Desert Research Institute of Reno, NV, provided archaeological services, and JFL & Associates of Boulder, CO, provided biological services. These efforts began in the fall of 1979 and continued through the summer of 1980. Conservative Design Criteria By adoption of conservation design criteria, flowsheets and processing data required for detail engineering were firmly established with a minimum of impact on schedule. On Oct. 21, 1980, HIMCO formally initiated a feasibility study to evaluate the Borealis project. Four organizations were contracted for particular scopes of work: • John T. Boyd Co.: Ore reserve estimation, preliminary mine plan, and mine capital and operating cost estimation. • Bechtel Civil and Minerals: Conceptual engineering, processing capital and operating cost estimation. • Hazen Research Inc.: Metallurgical testing. • Sierra Pacific Power: Cost estimation for power supply. Metallurgical testing and conceptual engineering of both heap and agitation leach flowsheets were investigated concurrently. Numerous economic evaluations were conducted for both heap and agitation leaching at varying production capacities. The results indicated a heap leaching flowsheet treating 454 kt/y (500,000 stpy) yielded the best economics and was compatible with the "fast-track" development goal. Conservative design criteria was established to provide operating flexibility and ensure plant productivities. A summary of major design criteria is presented in Table 1. HIMCO assembled the results of the studies of the various consultants along with internally generated studies to produce the feasibility document. The decision to supply 100% equity by HIMCO rather than arrange project financing help to expedite the project. Cooperation Between HIMCO and Regulatory Agencies With cooperation and mutual trust established between HIMCO and regulatory agencies, the time required for environmental permitting was streamlined as much as practical. To expedite the required construction permits, HIMCO proposed to the USFS that HIMCO fund the total cost of an Environmental Assessment Report (EAR) and that issues be addressed at the technical level of an Environmental Impact Statement (EIS). The previous studies on the critical issues of archaeology and biology provided HIMCO with the information to satisfy the proposed approach. Houston International Minerals and the USFS agreed to have Environmental Research and Technology (ERT) of Fort Collins, CO, prepare a draft EAR for the USFS.

Jan 11, 1983

By Brendan Demich, Brendan Macdonald, Timothy J. Orr, Jason Navoyski, Jennica L. Bellanca, William J. Helfrich

Recent advances in computing, rendering, and display technologies have generated increased accessibility for virtual reality (VR). VR allows the creation of dynamic, high-fidelity environments to simulate dangerous situations, test conditions, and visualize concepts. Consequently, numerous products have been developed, but many of these are limited in scope. Therefore, the National Institute for Occupational Safety and Health researchers developed a VR framework, called VR Mine, to rapidly create an underground mine for human data collection, simulation, visualization, and training. This paper describes the features of VR Mine using self-escape and proximity detection as case studies. Features include mine generation, simulated networks, proximity detection systems, and the integration and visualization of real-time ventilation models.

In spite of a global economy that continues to seesaw and a U.S. Congress that is at odds with the president and themselves, cities around the world are still spending billions on their infrastructure. And that bodes well for the underground construction and tunneling industry and the professionals who work in it. In June, 1,405 of those professionals gathered in San Francisco, CA for the Rapid Excavation and Tunneling Conference (RETC). In addition to the first rate technical programming, attendees were able to see first-hand the latest in tunneling technology from 127 exhibitors who occupied 152 booths. Two short courses preceded the conference and two field trips were offered following the conference.

Jan 1, 2011

In this paper, a mixed integer linear programming (MILP) model for the short-term scheduling of open pit mines is formulated. The proposed model aims at sequencing the blocks extraction over multiple short-term periods. The model takes into account multiple processes, waste dumps, and multiple stockpiles. The short-term scheduler makes a decision on the period, destination, and route that ore and waste are supposed to take to minimize costs while meeting all the mining and processing constraints. The destinations of the extracted materials are also controlled by their rock types. A monthly short-term production scheduling case study of an iron ore deposit is carried out over a year to validate the model.

Jan 1, 2011

By Ludger Suarez-Burgoa

At the Porce III Underground Powerhouse Complex in Colombia, the observational method (Peck, 1969), was used to provide information to an underground wedge and a 2D Finite Element Method numerical models, both used to estimate the mechanical behavior of the hoisting rock mass. The observation process consisted in collecting fault events in the field and in interpreting Multiple Point Borehole Extensometers and Surface Convergence Displacement Points readings. The calibrated models were employed to predict the behavior of the pillars formed between the machine and transformer caverns. The observational method is an important activity during excavation of large openings and provides arguments to understand the rock mass mechanical behavior.

Jan 1, 2008

By Yousef Ghorbani, Jafar Abdolahi Sharif, Fatemeh Kazemi, Ataallah Bahrami

Kinetic models are the most important tool for predicting and evaluating the performance of flotation circuits. Gilsonite is a natural fossil resource similar to an oil asphalt, high in asphaltenes. Here, in order to determine the kinetic order and flotation rate of a gilsonite sample, flotation experiments were carried out in both rougher and cleaner stages. Experiments were conducted using the combinations of oil–MIBC and gas oil–pine oil, with one test without collector and frother. Five kinetic models were applied to the data obtained from the flotation tests using MATLAB software. Statistical analysis showed that the results of the experiment with oil–MIBC were highly in compliance with all models. Kinetic constants (k) were calculated as 0.1548 (s−1 ) and 0.0450 (s−1 ) for rougher and cleaner stages, respectively. Rougher and cleaner tests without collector and frother also matched all models well (R2 > 0.98), with k values of 0.2163 (s−1 ) and 0.284 (s−1 ), respectively. The relationship between flotation rate constant, maximum combustible recovery, and particle size showed that the maximum flotation combustible recovery and flotation rate were obtained in the size range of −250 + 106 μm in the rougher and cleaner stages. The combustible recovery and flotation rate were higher in the rougher flotation process than in the cleaner stage.

By Yousef Ghorbani, Jafar Abdolahi Sharif, Fatemeh Kazemi, Ataallah Bahrami

Kinetic models are the most important tool for predicting and evaluating the performance of flotation circuits. Gilsonite is a natural fossil resource similar to an oil asphalt, high in asphaltenes. Here, in order to determine the kinetic order and flotation rate of a gilsonite sample, flotation experiments were carried out in both rougher and cleaner stages. Experiments were conducted using the combinations of oil–MIBC and gas oil–pine oil, with one test without collector and frother. Five kinetic models were applied to the data obtained from the flotation tests using MATLAB software. Statistical analysis showed that the results of the experiment with oil–MIBC were highly in compliance with all models. Kinetic constants (k) were calculated as 0.1548 (s−1 ) and 0.0450 (s−1 ) for rougher and cleaner stages, respectively. Rougher and cleaner tests without collector and frother also matched all models well (R2 > 0.98), with k values of 0.2163 (s−1 ) and 0.284 (s−1 ), respectively. The relationship between flotation rate constant, maximum combustible recovery, and particle size showed that the maximum flotation combustible recovery and flotation rate were obtained in the size range of −250 + 106 μm in the rougher and cleaner stages. The combustible recovery and flotation rate were higher in the rougher flotation process than in the cleaner stage.

By Tyler Acorn, Brandon Wilson, Jeff Boisvert

Scenario-level uncertainty is a representation of large-scale differences encountered when considering ultimate mining pits optimized over various subsets of stochastic realizations. Accounting for scenario-level uncertainty allows mine plans to be assessed against several probabilistic subsurface interpretations. Scenario-level uncertainty is found through clustering stochastic geostatistical realizations and optimizing final pits across the realizations in each cluster. Where these pits are geometrically different, plans for each scenario differ. Knowing these differences allows the value of each planning alternative to be assessed based on the value and relative probability of each scenario. These results also facilitate the use of formal decision-making frameworks for planning, leading to optimization that better represents the full statistical characterization of the deposit. An example utilizing this approach evaluates both infrastructure placement and drilling program requirements. In both cases, scenario-level uncertainty improves initial plans by limiting opportunity costs and identifying additional potential.

By Tyler Acorn, Brandon Wilson, Jeff Boisvert

Scenario-level uncertainty is a representation of large-scale differences encountered when considering ultimate mining pits optimized over various subsets of stochastic realizations. Accounting for scenario-level uncertainty allows mine plans to be assessed against several probabilistic subsurface interpretations. Scenario-level uncertainty is found through clustering stochastic geostatistical realizations and optimizing final pits across the realizations in each cluster. Where these pits are geometrically different, plans for each scenario differ. Knowing these differences allows the value of each planning alternative to be assessed based on the value and relative probability of each scenario. These results also facilitate the use of formal decision-making frameworks for planning, leading to optimization that better represents the full statistical characterization of the deposit. An example utilizing this approach evaluates both infrastructure placement and drilling program requirements. In both cases, scenario-level uncertainty improves initial plans by limiting opportunity costs and identifying additional potential.

By John A. Breslin

The year 2010 will mark the 100th anniversary of the beginning of the research efforts by the U.S. government to improve the health and safety of miners working in the United States. This research began in 1910 with the establishment of the U.S. Bureau of Mines (the Bureau) and it has continued during the past 10 decades, even after the closure of the Bureau in 1996. The research on safer mining technology, formerly done by the Bureau, has now been combined with National Institute for Occupational Safety and Health (NIOSH) studies of miners? health to form a unified federal research program to improve the health and safety of miners. This article describes this research and places some of the accomplishments into perspective with other activities in the U.S. Mine Safety and Health Time Line (insert).

Jan 1, 2010

By Ronald E. Heuer, Debra L. Virgens

INTRODUCTION Behavior of clay soils in response to tunneling is reasonably well understood by reference to the tunnel stability factor NT = Pz/su (Peck, 1969; Heuer, 1974). With this analysis tool, care must be taken to use a value of clay shear strength which represents the actual mass strength, considering such factors as slickensided fissures often found in stiff and hard clays. Behavior of clean sand and gravel soils is also reasonably well understood. Above the water table these soils must be assumed to act as running ground unless they are known to have significant cementation or have a very dense and angular interlocked grain structure. Below the water table they must be tunneled using some form of groundwater control such as dewatering, grouting, freezing, or internal fluid pressure in the tunnel such as compressed air or a slurry tunneling machine. The internal fluid pressure must approximately balance the external water head. Without such precautions these soils behave as flowing ground and may yield large volumes of water flow into the tunnel. A wide range of very fine sand, silty sand, cohesionless silt, and clayey sand soils exist in nature in a variety of geologic environments. The behavior of these soils in response to tunneling, and guidelines for anticipating their behavior, are not well described in the literature. Because of their content of fine particles, these materials may behave as if they initially have appreciable cohesion and moderate to low permeability. They may exhibit significant standup time, and require tunnel internal fluid pressure (compressed air or slurry pressure) less than the full external water head. It is important to be able to estimate the behavior of these soils when planning construction methods. For example, if the external water pressure is 140 kPa (20 psi), but soil stability at the tunnel face can be achieved as a compressed air pressure of 80 kPa (12 psi), a large cost savings may result.

Jan 1, 1987

By H. Tudeshki, A. Tayebi

"The large extent of global production and consumption of aggregates from quarries, grabs one´s attention and makes its substantial and essential standpoint in the world today pretty clear. A great amount of aggregates is utilized in civil engineering applications such as road construction, railway industry, concrete production, etc. Considering this fact that igneous rocks display a higher strength and abrasion resistance, this type of rock is preferred in the field of civil engineering. For all these applications, rock quality assurance is a key factor and certainly unavoidable, and it has great influence on the quality of constructions in civil engineering. One of the major problems encountered by both the producers and users of igneous rock is the fact that, with the passage of time, some specific rocks lose their strength, up to a complete loss of structure or in other words, their disintegration and degradation. In the last decades, different methods and procedures such as Glycol test, methylene blue dye test, as well as the Los Angeles test have been introduced to distinguish these rock properties, and to identify these problems. However, as these methods are time consuming, hard to perform, only to be applied to hand-piece samples, requiring special laboratory equipments, and only possible to be accomplished under laboratory conditions, their application has always been limited to some specific cases, and they are neither recommendable nor advantageous. In addition, these methods provide partially different results for the same rock. To address this widespread quality management problem of the quarry industry, a relatively quick, easy and user-friendly approach is necessary. It calls for a systematic solution with a device that can simply be used day to day in a mine for quality control of the quarry´s daily production. This scientific research is concentrated on developing a systematic method for early recognition and diagnosis of rock quality, in order to control and manage the quality of the quarry production in advance. This method was developed, based on the procedure of the magnetic susceptibility measurement. The obtained values can lead to valuable information regarding the quality of the rock and allows the quality control process to be accomplished and performed at the borehole location. This approach has been assessed through extensive field and laboratory studies. A detailed and comprehensive discussion will be made on the results of the experiments. The advantages and impacts of the application of this method, on increasing the reserves and environmental protection are also discussed."

Jan 1, 2011

By Shaoxian Song, Ling Xia, Hongqiang Li, Yubiao Li, Yunliang Zhao, Shaobing Xie

Since human daily demands for fresh water have been increased significantly, the supply of fresh water for the mining industry, especially froth flotation, should be considerably reduced. In addition, stricter environmental standards have been implemented in many countries to reduce the risks due to the disposal of wastewater, many flotation operators have to seek more efficient ways to utilize the limited fresh water sources. Recycling water with high concentrations of impurities is a normal strategy for most of the mineral processing plants; however, water quality should be carefully considered to guarantee a smooth flotation process. Recently, the application of seawater in flotation has attracted much attention due to its availability and abundance rather than fresh water. However, the influencing mechanisms due to the application of seawater in flotation have not been fully understood especially the reactions between mineral particles and bubbles in the presence of high concentrations of cations and anions. This would impede the application of alternatives to fresh water in the flotation. Therefore, this paper reviews the current water sources and the technologies for water recycling in the flotation process. Specifically, the life cycle of water in flotation was proposed. In addition, the strategies including high pulp density flotation as well as the most promising alternatives to fresh water have been discussed in details, with the related mechanisms being demonstrated.

By Zhigao Xu, Ming Wu, Jun Qu, Rong Zhang, Wenrui Nie, Ruan Chi, Zhenyue Zhang, Zhengyan He

The leaching processes and mechanisms of weathered crust elution-deposited rare earth (RE) ores with ammonium sulfate were investigated for their high efficiency and low consumption exploitation. The leaching process is a typical reversible heterogeneous ion exchange reaction in liquid–solid systems. The raw ore and leached tailings were analyzed by SEM and FTIR. Results indicated that no dissolution or structural changes of the ores occurred during the leaching process. The migrations of RE3+, Al3+, and NHþ 4 in the leaching process were studied under various liquid–solid ratios. With increasing liquid–solid ratio, the content of NHþ 4 adsorbed on clay mineral by physical effect decreased, NHþ 4 adsorbed by ion-exchange increased, and the content of exchanged RE and Al increased until reaching equilibrium. The adsorption capacity of the RE ores for NHþ 4 remained about 0.61–0.63 mg/g. It was difficult to desorb NHþ 4 from RE ores with washing water alone. The leaching mechanism of Al was the same as RE, but the leaching of Al slightly lagged behind RE. At the optimal liquid–solid ratio of 0.4:1, the leaching efficiencies of RE and Al were 95.51% and 90.99%, respectively, and 56.65% of NHþ 4 remained in the leachate. After impurity removal and RE precipitation, the leachate can be reused by replenishing fresh leaching agent. The aim of this study is to enhance the leaching process of RE, restrain the leaching of impurities, and decrease the consumption of leaching agents.

By Zhigao Xu, Ming Wu, Jun Qu, Rong Zhang, Wenrui Nie, Ruan Chi, Zhenyue Zhang, Zhengyan He

The leaching processes and mechanisms of weathered crust elution-deposited rare earth (RE) ores with ammonium sulfate were investigated for their high efficiency and low consumption exploitation. The leaching process is a typical reversible heterogeneous ion exchange reaction in liquid–solid systems. The raw ore and leached tailings were analyzed by SEM and FTIR. Results indicated that no dissolution or structural changes of the ores occurred during the leaching process. The migrations of RE3+, Al3+, and NHþ 4 in the leaching process were studied under various liquid–solid ratios. With increasing liquid–solid ratio, the content of NHþ 4 adsorbed on clay mineral by physical effect decreased, NHþ 4 adsorbed by ion-exchange increased, and the content of exchanged RE and Al increased until reaching equilibrium. The adsorption capacity of the RE ores for NHþ 4 remained about 0.61–0.63 mg/g. It was difficult to desorb NHþ 4 from RE ores with washing water alone. The leaching mechanism of Al was the same as RE, but the leaching of Al slightly lagged behind RE. At the optimal liquid–solid ratio of 0.4:1, the leaching efficiencies of RE and Al were 95.51% and 90.99%, respectively, and 56.65% of NHþ 4 remained in the leachate. After impurity removal and RE precipitation, the leachate can be reused by replenishing fresh leaching agent. The aim of this study is to enhance the leaching process of RE, restrain the leaching of impurities, and decrease the consumption of leaching agents.

Ceremonies for the induction of five mining industry pioneers into the National Mining Hall of Fame will be on Sept. 12, 2009 at the Charles F. Barber Pavilion of the Museum Convention Center in Leadville, CO. The five inductees are: Paul A. Bailey, 82, Richard T. Moolick, 89, William Braden and Alonzo Pawling and Henry Harnischfeger. Paul A. Bailly was president of Bear Creek Mining Co., the U.S. exploration subsidiary of Kennecott Copper, from 1961 to 1967. In 1968, he joined Occidental Petroleum Corp. and was tasked with creating the company?s international mining division, Oxymin, which he led as president through 1983. During his distinguished career, Bailly participated in numerous significant mineral discoveries, developed a new exploration philosophy and made important additions to the mineral exploration literature. William Braden was the first to recognize the immense potential of the El Teniente orebody in Chile. He founded Braden Copper Co. and developed the El Teniente Mine which now, 100 years later, remains the world?s largest underground copper mine. Braden?s endeavor survives to-day as the El Teniente division of the Chilean state copper company, CODELCO. T. (Dick) Moolick established a lasting legacy in the mining industry, first during a 35 year career with Phelps Dodge Corp. and then as the driving force in establishing the National Mining Hall of Fame and Museum in Leadville. The Hall of Fame and Museum ? a monument to the memory of the men and women who pioneered the discovery and development of the United States? natural resources ? has become one of the fi nest museums in the western United States.

Jan 1, 2009

By Steve Kral

In a lagging economy where profits are tight, businesses cut costs. No revelation there. The mining industry, though, has always looked for ways to reduce production costs — no matter the state of the economy or commodity prices. The fact is, when planning a new mine or the expansion of an existing one, mining companies gamble that commodity prices will be reasonably high when a project comes onstream. It takes millions of dollars and several years to bring a mine into operation. And a lot can happen economically between the time management gives the go-ahead for a new project and its completion.

Jan 1, 2002

By C. D. Elifrits, N. B. Aughenbaugh

Introduction Federal and state laws enacted to regulate coal mining and the accompanying public concern about the adverse effects that mining might have on land use have focused much attention on the subsidence of the land surfaces over underground mines. Some questions asked are: • Will abandoned mines subside in the future even though they have exhibited no surface adjustment to date? • If so, when will subsidence take place? • Can a specific surface area be affected by subsidence more than once? • What surface form will the subsidence feature take? • Is there any way to predict when subsidence will occur and end? An attempt is made here to address these questions insofar as it is possible with available data and experience of evaluation of subcritical extraction conditions. Mining that results in subsidence features can be classified as supercritical, subcritical, and critical with respect to the minimum span lengths of the worked-out rooms (Fig. 1). A complete basin will not develop fully immediately over subcritical conditions because the span lengths of the entries are less than the critical dimension (Wardell, 1983). Passageways, entries, and room-and-pillar panels are all included in the subcritical category. Because of the short span lengths, subcritical mining conditions tend to be stable over the life of the mine unless adverse geologic conditions exist (Gray et al., 1974; Dunrud, 1976). Various roof control and support procedures are employed to maintain entry stability during mining. Little information exists concerning the time factor of subsidence over areas of subcritical extraction. Data that have been collected relate to longwall mines, whereby the cavity sizes are designed large enough to induce caving behind the working faces so that complete subsidence at the surface occurs within a short period of time. The UK's National Coal Board (1975) has reduced the enormous amount of data it has collected to empirical correlations and has published these correlations in its Subsidence Engineers Handbook. The handbook states that "None of the foregoing remarks applies to pillar and stall working," with respect to the section discussing the time factor of subsidence caused by longwall mining (National Coal Board, 1975, p. 40). To understand and evaluate how time relates to subsidence above room-and-pillar mines, one must first recognize how mine cavities deteriorate and fail. The propagation of failure to the surface must then be studied, and, finally, the failures that are manifest at the surface in the form of depressions accompanied by both compressional and tensional movements must be investigated. Failure of mine cavities Any cavity beneath the earth's surface represents a condition of nonequilibrium and tends to close with time. Failure of cavities in a subcritical mine can be classified as failure of the roof, failure of the floor, failure of the supports (pillars, cribs), and elastic rebound of the rock. One mode of failure may dominate, but generally combinations of the four will occur. Also, initial instability of geologic materials and structural features and in situ stress may be unknown factors that can contribute to cavity failure. Roof failure is the most obvious opening stability problem in most operating mines. The bridging capabilities of the roof rock are dependent on the rock's material strength, geologic discontinuities, and reaction to humidity changes in the air of the mine. This type of failure may vary in magnitude from gradual flaking to massive roof falls. Mine floor instability can be manifest in the form of a general heave over a broad area or of individual pillar punching. The weaker and thicker the immediate floor material, the more prone a mine is to experience floor problems. Water seeping into an area can soften the underclay, reduce its bearing capacity, and precipitate failure of support for the overburden.

Jan 8, 1986

By Charles Stone, Madan Naik, Drupad Desai, Karel Rossler

Planning of New York’s new subway line dictated the location of shallow underground station caverns and track crossovers. Clear span openings ranging from70 feet to 100 feet and lengths in excess of 1000 feet, coupled with low rock cover ranging from 25 feet to 40 feet required judicious selection of construction methods, equipment, and proper sequencing of the excavation stages. Rock classifications alone could not predict the behavior of the rock mass during construction. A robust design procedure that considered most of the important aspects of rock behavior and elements of shallow tunnel design, minimized the negative impacts of variable geotechnical data. This paper describes the intricacies of the planning and design of the $16 billion Second Avenue Subway with insight into how to overcome the design complexities and construction challenges of the urban underground.

Jan 1, 2005