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By Douglas G. Hubert

To put coal in its proper perspective as a source of energy for electric power production, we must first compare it to other energy sources. A report of the Atomic Industrial Forum dated February 1958 records a number of authoritative though widely varying predictions. The most optimistic of these states that by 1968 there will be a total U.S. capacity of about 6000 megawatts of nuclear power, if growth continues at the present rate. Other sources indicate over 200,000 megawatts of total electrical capacity in utility plants by 1968. This is only 3% nuclear. Therefore, 97% of our total power production will be from non-nuclear energy. Fig. 1 shows the distribution of energy sources of electric utility product- ion in the U.S. as reported by the Federal Power Commission in 1954. Note that less than one quarter of the total is hydro and about one half of the total is coal. For 1957, the Edison Electric Institute reports that of the total steam- electric generation in the U. S., 68.6% was by coal, 7.9% was by oil and 23.5% was by gas. This is an increase for coal and a decrease for oil and gas in those three years. Thus we can conclude that two-thirds of the steam-electric power in the U. S. is now generated by coal. Fig. 2 shows the major markets for coal for 1947 vs 1957. The greatest in- crease has been in the electric utility market, where it has more than doubled in the ten years. One-third of the total coal produced goes to the utilities which now represent coal?s major market. Utilities used 160 million tons of coal in 1957, and the estimated quantity for 1967 is 275 million tons, and for 1977 is 525 million tons. It is predicted that 85% of steam-electric power will be generated by coal in 1975.

Jan 1, 1959

By Ingo Ossenbühl, Wolfgang Dolsak, Vojtech Gall, Axel G. Nitschke

"Yielding support systems for application in underground construction have a long history, primarily in mining. Typical examples are tunnels subject to loading conditions that lead to overstressing of the newly installed support or existing tunnel structures in active fault zones. Recent applications for tunnel rehabilitation projects unveiled the capabilities and flexibility of combined yielding support systems presented in this paper. Frequently, the main requirements for tunnel rehabilitation applications are a fast, safe, and simple installation along with the need for flexibility with regards to existing tunnel geometries. A combined support system consisting of steel sets with yielding connections and special groutable hoses has proven to be an efficient support measure providing a multitude of advantages compared to conventional rehabilitation approaches. The presented yielding support system provides an immediate and active support, while it allows for controlled yielding upon experiencing loads beyond its support capacity. INTRODUCTION The excavation of underground spaces leads to redistribution in the existing stress regime. This load redistribution goes along with deformations in the surrounding rock mass. Magnitude and duration of these deformations depend on the tunnel’s depth and geological conditions, but also on the installed support system. Modern civil tunneling infrastructure has generally an envisioned service life of about 120 years. Conventional tunneling provides typically a dual support system, split into the initial (or primary) and final (or secondary) lining. A typical design principle in civil tunneling is to let the vast majority of deformations acting on the initial lining cease, before the final lining is installed. Based on this approach, the loading on the final lining is significantly reduced and signs of overstressing, such as cracking of the lining, are typically limited to the initial lining. However, special cases in swelling and squeezing ground require different approaches, including yielding support systems."

Jan 1, 2016

By A. D. Trujillo, R. D. Wunder

The Chino Mines Co., a Kennecott- Mitsubishi partnership, located in Hurley, NM, recently completed a $405 million modernization of its mine, concentrator, and smelter facilities. The mine/concentrator modernization commenced in 1980, and the smelter modernization began during 1982. Modernization of the mine and concentrator facilities involved increasing the mining rate from 98 kt/d (108,000 stpd) to 152.2 kt/d (167,800 stpd). Ore mining was designed to increase production from 20.2 kt/d (22,300 stpd) to 34 kt/d (37,500 stpd). A new concentrator was con- structed near the mine using semiautogenous grinding. The new smelter uses the INCO flash smelting process, increasing capacity by 40.8 kt/a (45,000 stpy) to 99.8 kt/a (110,000 stpy) of saleable copper.

Jan 1, 1988

By R. W. M. Lai

The study of flotation kinetics was first reported by Garcia-Zuniga1 in 1935. Since then, literature on the subject has grown with the time. 2-19 Although there is an abundance of flotation kinet¬ics models available in the literature to describe flo¬tation systems, they are mostly of academic interest and are seldom applicable for use in the industrial environment. Several reasons contribute to the wide gap in the industrial -application of the academic models. These include: 1) the lack of generality in the model, e.g., the model is limited to certain size ranges; 14 2) the academic models involve complicated mathematics; 5,6,10,11 3) confusion about the order of the flo¬tation rate, e.g., several authors proposed a first order rate model, 1,15,16 whereas the others propagated a second order rate model: 2,17,18,194) the use of an unrealistic rigid value, such as the use of a maximum recovery of 100%, 5,8,19 which is unrealistic in industrial operations; and 5) the use of graphs that confuse the reader rather than interpret information. 2,3,10 This paper intends to introduce a simple and easy to understand empirical flotation kinetics model along with a way of presenting the model in an informative graphical form, which should stimulate the interest of other practical engineers to become concerned with practical application within the mineral industry.

Jan 1, 1982

By T. Hackett

Western underground coal reserves are tremendous, but recovery in western seams can be poor because of mining problems caused by deep cover, geologic anomalies, and thick seams. For instance, many seams contain a rock parting too thick to be extracted economically with the coal. This forces the operator to mine the coal above or below the parting. Subsequently, the rock pressures induced by mining make the part left difficult or impossible to extract by standard mining methods. Because upper and lower parts of the seam are frequently of minable thickness, the presence of rock partings can result in a significant loss of coal. Given a longwall recovery of 60 pct and equal thickness for the two parts of the seam, overall recovery is reduced to less than 30 pct if one part only is mined. The coal left in place is unavailable to meet the nation's energy needs, or to produce revenues for coal companies or government. [ ] Multi-slice longwall mining has the potential to recover the portion of split seams that are now left in the mine. Using superimposed standard longwalls with chain pillars, overall recovery could be doubled, depending on panel and pillar widths. Using a combination of advancing and retreating longwalls in descending slices, overall recovery could be improved to more than 80 pct. Because of the potential for improved recovery, the Bureau of Mines is analyzing the ground control factors affecting multi-slice longwall under western mining conditions and is conducting field trials at a planned multi-slice operation.

Jan 1, 1987

By William J. Taylor

Strictly defined, a stull is an inclined or horizontal timber support; a vertically placed timber is defined as a prop. Common usage allows the catchall term "stull" to refer to all such uniaxial mine support, regardless of orientation. Typically a stull is a round wooden column that is wedged in place to provide short-term auxiliary support between sill and back, or between hanging wall and footwall. Stulls may be used exclusively or in con- junction with other support systems such as roof bolts, shotcrete, or cribbing. Stulls are used both as local temporary support in stoping operations and for uniform systematic support installations. Where stoping areas are to be abandoned soon after excavation, stulls may be used to provide temporary support during mining operations. Where controlled caving and subsidence is required, stull supports are designed to fail in a systematic, predictable manner. Wood type is selected on the basis of availability, price, and load carrying characteristics. Coniferous woods are typically used, especially to carry heavy ground loads. Brittle woods are generally avoided because of their tendency to fail suddenly. Gradual yielding failure is preferable to sudden, unexpected failure of the support. Some usage of wood from deciduous trees such as cottonwood and other poplars has been reported in Grants, NM. These stulls reportedly mushroomed as the ground load increased but continued to maintain their structural integrity. Stulls fabricated from structural steel are used in special applications. Adjustable lengths are commercially available in mechanical, hydraulic, and pneumatic designs. The high cost of mechanical stulls limits their use to mining systems where recovery and reuse is possible. End blocking, also called headboards or footboards, uses wood blocks that are placed between the stull end and the ground they are supporting. The blocks are typically 50.8 to 101.6 mm (2 to 4 in.) thick, 203.2 to 304.8 mm (8 to 12 in.) wide, and 381 to 609.6 mm (15 to 24 in.) long. End blocking serves to distribute the support over wider back area. Compression of the end blocking gives visual indication of wall movement prior to failure of the stull. A common application of the stull is in flat-bedded uranium mining during pillar extraction. Many western US uranium mines use a pillar pattern development to delineate the irregular ore pods. After development of an appropriate sized pillar, the ore pillars are then sequentially mined out, leaving the undercut hanging wall or back to cave. Where thickness of the ore is less than 4.3 m (14 ft), stulls are generally used to provide ground control as the pillar is removed in slices. Experience dictates the density of stull placement. In general, the number and size of stulls should be sufficient to resist ground closure and to provide support for drilling and loading operations adjacent to the pillar. Stulls next to the mining face are often lagged 0.9 to 1.2 m (3 or 4 ft) up from the floor (or sill) to confine the blasted ore to a passage next to the pillar. Mucking is simplified by this confinement. Experience dictates whether back control along a mining face requires removal of stulls to allow con- trolled subsidence of the back or hanging wall. Without caving or closure, abutment pressure can create poor ground conditions near the pillar.

Jan 1, 1982

By M. P. Saunders

A comprehensive, site specific water management plan is of primary importance to the successful implementation, operation and decommissioning of any mining project. Formulation of a plan requires an orderly planning process consisting of identifying problems, establishing planning criteria based on the guidelines and requirements of regulatory agencies, and an iterative procedure of identifying, investigating, and evaluating plan elements and alternative plans. A typical uranium surface mine operation consists of a mine pit or pits, spoil pile areas, crusher, processing plant, and tailings disposal area. A water control plan addresses the problems of diversion of natural runoff from undisturbed areas around the mine; and diversion, collection, and treatment of runoff from within the mine area. A water control plan is required to determine the location and size of appropriate control and detention structures; their cost; and the schedule for permit activity, design, and construction. The plan must be formulated to meet the requirements of both the State and Federal regulatory agencies.

Jan 1, 1981

By David B. Crouch

Wastes in various forms have always been a part of mining, and management of mine waste has evolved from the early days of "push it over the side and down the creek" to today's highly engineered waste facilities. Changes have been brought about not only by technological advances in the ?3M?s? - mining, milling, and metallurgy - but also by environmental awareness and changing social values that have been manifested in an ever-growing maze of regulations. This is a dynamic era, and the debate goes on. So it is that planners have to anticipate permit and regulatory requirements in the site-selection process along with the traditional criteria. The McLaughlin gold project is an example of how one company, Homestake, has met this planning challenge. In August of 1980, Homestake Mining Company announced a major gold discovery in northern California known as the McLaughlin Project. The property is approximately 80 air miles northeast of San Francisco near the junction of Lake, Napa, and Yolo Counties. This is an area where mercury has been mined off and on for over 100 years; gold has never been mined in the area. The gold is microscopic and finely dispersed in a complex geologic setting. Reserves are estimated at approximately 20 million tons at a grade of approximately 0.16 ounces per ton.

Jan 1, 1983

By W. E. Hale

The Institute of Applied Geology (I.A.G.), a joint project sponsored by the University of the Philippines, the Philippine Bureau of Mines and the United Nations Development Programme (Special Fund) undertook during 1965-66 a number of field projects in Northern Luzon Island (Fig. 1). These field operations were of a two-fold nature: during approximately six weeks an orientation survey, involving, geology, geophysical surveying, and geochemical prospecting, was conducted over a partly developed, disseminated copper deposit at Sto. Nino (Fig. 1). The Sto. Nino study demonstrated (Hale and Govett, 19677 Govett and Hale, 1967) the feasibility of geochemical prospecting relative to other exploration methods for the location and delineation of disseminated copper occurrences, the major source of metal in the expanding mineral industry of the Philippines. A vein occurrence at Suyoc (Fig. 1) was similarly subjected to

Jan 1, 1968

By R. V. Ramani, K. V. Raj

"The air flow problems in open pit mines are complex. Computational fluid dynamics (CFD) models provide a detailed knowledge of the airflow pattern and velocity distribution, temperature, and pollutant concentration within an enclosed domain of the open pit. A range of turbulent model can be selected for varying complexity and accuracy. Pollutant transport models, however, differ in their assumptions and structure as well as in the algorithm they use; as a result, prediction varies from model to model. This paper presents a study of pollutant transport in an actual open pit mine under stable boundary layer. The objective is mainly to test two turbulence models using the same input conditions, model constants, and similar geometry. Measured data are used to compare results of the two CFD models, namely, the kappa-epsilon (?-e) model and the Large Eddy Simulation (LES) model. Despite the complex synoptic situations, different meteorological input data and the fast changing conditions, the simulation results from both the models are in good agreement regarding the dispersion of pollutants.INTRODUCTION Modeling of contaminant transport under Arctic air inversion is an important step for an assessment of the amount of pollutants within the open pit. The Airflow in open pit mines is of larger scale and does not follow the principles of pipe flow. The air flow problems in actual open pit mines are thus far more complex. CFD models provide a detailed knowledge of the airflow pattern and air velocity distribution, temperature, and pollutant concentration within an enclosed domain of an open pit. There is no known application of CFD in three-dimensional modeling of air flow in large open pit mines. Two equation RANS kappa-epsilon (?-e) and Large Eddy Simulation (CFD) models, however, have been developed to solve the stable boundary layer (SBL) problems in Atmospheric Sciences (Baklanov 2000, Basu and Porté-Agel 2006, Dop and Axelsen 2007, Bandopadhyay et al. 2014). Because an exact flow situation in open pit mines is not known a-priori, it is therefore, necessary to investigate various turbulent models to identify the appropriate model that would simulate the flow phenomena with reasonable accuracy, and predict the contaminant distributions within the pit. Dispersion models differ in their assumptions and structures as well as in the algorithm they use and, as a result, predictions vary from model to model. Furthermore, it is also important to investigate the behavior of a CFD model in simulating a complex phenomenon such as the transport and distribution of contaminants in open pit mine under Arctic air inversion. The simulation of an enhanced period of turbulence in SBL is of particular interest because traditional air pollution dispersion models cannot explicitly treat such intermittent events, and yet the SBL is often the worst-case scenario in an open pit pollution transport"

Jan 1, 2015

By William W. Shriver

When the Henderson Project is completed in 1975, it will become one of the Free World's largest primary molybdenum producers. The Henderson Mine will be located approximately 50 miles west of Denver, Colorado, on the eastern slope of the Continental Divide. Ore reserves are currently estimated to be 303,000,000 tons with a grade of 0.49% MoS2. The mill and tailing area will be located approximately 14.5 miles from the mine in the Williams Fork Valley, which is on the western slope of the Continental Divide. Ore haulage from the mine to the mill will be by ten miles of underground railroad and 4.5 miles of surface railroad. The concentrator has been designed to mill 30,000 tons per day and will yield approximately 50,000,000 pounds of contained molybdenum per year. This paper is concerned with the tailing and water supply system for the Henderson Project and in particular the environmental considerations affecting their design.

Jan 1, 1970

By Raymond T. Moore

The Federal Coal Mine Health and Safety Act of 1969 (FCMHSA) begins with this statement: "Congress declares that the first priority and concern of all in the coal mining industry must be the health and safety of its most precious resource -- the miner; . . ." At the Federal level this responsibility is shared by the Department of the Interior and the Department of HEW. The health research and standard setting activities under the Act are largely the responsibility of the Department of HEW, and with the exception of Title 4, Black Lung Benefits, have been delegated to our Institute, which I will refer to henceforth as NIOSH. In addition, we bear certain joint responsibilities with the Department of the Interior. These include dust sampling and respirator approval. To complete the picture, the Department of Labor has recently assumed Black Lung Benefit respon¬sibilities from the Social Security Administration under Title 4 of the Act.

Jan 1, 1974

By H. EI-shall

In this paper, the results of a fundamental study involving zeta potential and turbidity determinations of solid suspensions are discussed. Illustrations of how these results are utilized to design field applications of solid grade polymers to clarify mine drainage water are presented. Other applications in different industries are also reported. The operational and economical advantages are examined.

Jan 1, 1994

By W. J. Schlitt, K. McNaughton

A heap-leach field test was conducted during the 1993-1994 winter season at Carmacks, Yukon Territory, Canada. The purpose of the test was to demonstrate the viability of heap leaching Carmacks oxide copper ore in an arctic setting on a year-round basis. The test itself utilized a 5-m-diam crib loaded with 250 t of composite ore from the Carmacks copper deposit. The ore was stacked to a total height of 7 m in the crib, including 1 m of ore as an over- layer above the emitter system. This matched the plan for the commercial heap at the time when the test was started. The design also replicated an interior segment of the commercial heap. Leaching was done at a flow rate of 0.2 L/min/m2 using leachate at 21 °C. This temperature was maintained with no external heat input other than normal process heat transferred from electrowinning to the leachate via solvent extraction. Winter conditions were quite typical of those expected at the mine site. The temperature reached -54°C, while averaging -13°C over a three-month period. In spite of some flow system problems, leaching continued unabated, and freezing was limited to the insulating ore over-layer and isolated points near the outer crib walls. Thus, the test demonstrated that year-round heap leaching of Carmacks copper ore is practical in an arctic setting.

Jan 1, 2000

By Daniele Martinelli, Rodrigo Winderholler, Daniele Peila

"This paper presents a technical description of an experimental procedure developed for the geotechnical characterization of granular soils conditioned for EPB tunneling using a modified direct shear box. As the main concerning parameters of the conditioned soil mass were their undrained properties, in order to preserve its pseudo-fluid characteristics, a watertight direct shear apparatus was constructed. A comparison between the results obtained under dry, saturated and conditioned conditions is presented. INTRODUCTION EPB shield machines have been used for tunneling excavation in many different types of soils thanks to the use of soil conditioning agents. These modify the properties of the soil into that of a plastic paste, thus permitting the homogeneous flow of the excavated soil from the tunnel face through the bulk chamber, the screw conveyor and finally the conveyor belt. Moreover this technique allows controlling the face pressure and its regulation in the bulk chamber, preventing water inflow when tunneling below the water table. Further advantages are a drop of the cutter head and screw conveyor torque and reduction of the friction between metallic parts and the soil, consequently reducing wear phenomena (Merritt & Mair, 2006; Vinai et al., 2007; Borio et al., 2010; Thewes & Budach, 2010; Herrenknecht et al., 2011; Barbero et al., 2012; Peila, 2014). Several studies have investigated the possibility of conditioning and the chemical materials to be used in different types of soils, mainly subdivided into three groups: cohesionless soils (sand and gravel), silts and clays, and rock masses. This various researches have set up several laboratory procedures for these achievements before and after soil conditioning, as stated in Thewes & Budach (2010) and Peila (2014) (for cohesionless soils), in Thewes & Burger (2005), Hollmann & Thewes (2013), Zumsteg et al.(2012) (for clay), in Peila et al. (2013) and Martinelli et al. (2015a) (for rock mass). Such tests should be simple to execute, reliable and easy to interpret at the in-situ excavation step. The reduction of shear strength is necessary in EPB operations, since it allows an effective transmission of the pressure from the material itself to the front. In some cases the slump is not sufficient to return a reliable result on the shear strength reduction, as in some cases some materials are behaving differently. Therefore this research is aimed to study this aspect more in detail, in order to show the effectiveness of the soil conditioning process on the material to be excavated."

Jan 1, 2016

By T. Rockley, B. Goertz, S. McDaniel, J. Brune, K. Bakhsh

"Researchers at the Colorado School of Mines, under a project funded by the Alpha Foundation, have developed a working prototype of a dust sample collection device designed to determine if sufficient rock dust has been placed in an underground coal mine to prevent coal dust explosions. When used in conjunction with the Coal Dust Explosibility Meter (CDEM), the device will provide near instantaneous results on the quality of rock dusting at the tested location. The sampling device applies a pulse of air to a testing surface and collect a representative sample of mine dust based on the pneumatic entrainment process during a mine explosion. The use of both physical testing and Computational Fluid Dynamics (CFD) modeling has allowed researchers to refine the design to accurately represent the particle entrainment and optimize the sample size collected for the CDEM. The prototype is being tested in a mine environment to produce information of usability and practical aspects of mine dust sampling. This paper is a progress report summarizing the current status of sampler development. Researchers expect to have a fully developed and tested sampler in early 2016. INTRODUCTION Underground coal mines face the danger of methane and coal dust explosions. The disaster at Upper Big Branch mine (2010) has demonstrated the impact of a violent coal dust explosion that fatally injured 29 miners. Reviewing the history of coal dust explosions, researchers found that that mine operators and mine inspectors do not have a reliable method of collecting dust samples to assure that sufficient amounts of rock dust have been places to inertize the coal dust. This is a problem specifically with small mines that do not have dedicated safety departments to track rock dusting work. The aim of this research is to develop a simple, portable device that can help underground mine examiners collect dust samples from workings and test the explosibility of the sample near instantaneously. Researchers determined that the current brush-and-pan sampling method required by MSHA (MSHA 2013) is flawed in several aspects: Mechanical sampling with a brush exerts forces on the mine dust that may differ significantly from those present during an explosion. Also, U.S Bureau of Mines research (Nagy 1965) has determined that only the top 0.125 inches of the mine dust layer will be entrained in a coal dust explosion. Using a handheld pan and brush, it is difficult to correctly and repeatably sample a layer of this exact thickness. The following will describe the CFD modeling and experimental testing for the development of the prototype sampler. Researchers analyze the accuracy and performance of the prototype during the course of the build process."

Jan 1, 2015

By Daniel H. White

Block caving, unlike most other conventional forms of mining relies principally on the natural forces within the rock mass to fragment and transport the ore. Obviously, not every orebody can be satisfactorily mined by block caving. In the early stages of mine planning an attempt should be made to assess the benefits of the block caving system relative to others, and develop a reasonable mining concept that may be used to provide preliminary information to mine planners and financial specialists. It is the intention of this paper to outline some basic geotechnical parameters that are essential to: 1) Assessing the feasibility of block caving an orebody and 2) Providing semidetailed information relative to mine design based on drill hole and other data.

Jan 1, 1979

By J. M. Mutmansky

The SIMAN (SIMulation ANalysis) computer language is a general-purpose, discrete-continuous simulation language for modeling a variety of multi-component systems. The language has been described by its author in a textbook (Pegden, 1985) and in a paper (Pegden, 1986) and is available in a mainframe version, a minicomputer version and a microcomputer version. The language was designed for and has been extensively used for modeling manufacturing systems but possesses many features that are advantageous in the modeling of mining materials handling systems. Consequently, the authors have applied the language to the simulation of an open pit shovel/truck operation to test its usefulness for simulating mine materials handling systems. This paper presents a short background on simulation languages, the capabilities and modeling framework of the SIMAN language, a description of the application of SIMAN to a shovel-track operation and some results and conclusions on the use of the language for mining materials handling systems.

Jan 1, 1988

By Lynn B. Hales, Randy A. Ynchausti

Object-oriented technologies have been developed to more closely model the way we think about the world and our natural approach to solving problems. Higher levels of abstraction, generalization and classification are benefits of an object-oriented approach. Object-oriented programming, design, and expert systems are part of this technology which is shaping the future of real-time supervisory control. Goals of real-time supervisory control systems include: minimizing variations in process operations, improving efficiency, maximizing production, and implementing procedures for starting and stopping the process. Incorporating object-oriented technology in design, development and implementation of real-time supervisory control systems provides new opportunities for these tasks. This paper discusses some of the opportunities and challenges of implementing real- time supervisory control using an object-oriented expert system for a rougher flotation circuit

Jan 1, 1993

By J. Kulczycka

The concept of sustainable development is be-coming present in the policies of increasing number of industries and governments. The complexity affects not only production aspects, but has also special relevance for environmental decision making. Not only producers are re-evaluating the services they expect from the environment and concomitantly increasing their willingness to sacrifice other consumption in favour of enhanced environmental services, but the character of environmental issues is becoming more complex as well. Incomplete information, uncertainty, system wide change, trans-frontier impacts, current causes that have far reaching future effects, irreversibility, and possibilities of catastrophic change all complicate the environmental decision making process. Non-ferrous metals production, due to a relatively low level of metals content in ore, results in generating huge amounts of tailings, exceeding usually 90% of the mine output. They must be stored in special facilities, which have the significant impact on the environment both during tailing management facilities (TMF) operation and after their closure. One of the most essential impacts of operating and closed TMFs is their eolic activity, displaying in worsening air quality, aero-sanitary conditions in the neigh-boring villages and contamination of soils close to the facility by heavy metals.

Jan 1, 2005