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By J. Engesser

A research project was undertaken to determine if coal addition tofluxed-magnetite pre-fired pellets would reduce nitrogen oxide (NOx)emissions during pellet induration. Iron oxidation rate tests, coal oxidation rate tests and calcination rate tests were conducted in a laboratory furnace to determine the amount of coal necessary to provide adequate heat for limestone calcination without producing detrimental effects to magnetite oxidation. Pilot scale pot-grate tests were then performed with and without coal in the pre-fired pellets to verify pellet quality parameters and nitrogen oxide emissions. The off-gas during each pot-grate test was analyzed for NOx, CO2, CO, SOx, and O2. There was approximately a ten percent reduction in NOx emissions with coal addition during the normal pot-grate firing cycle. There was a 75% reduction in NOx emissions during firing cycles that used 25% to 75% excess air during firing rather than the normal 300% excess air.

Jan 1, 2003

By M. K. McCarter

INTRODUCTION Mining activity and basic geometry of open pit mines represent major obstacles in geotechnical mapping. Mining creates a constantly changing topographic base which may require corresponding updates of field sheets before mapping can proceed. The rapid pace of mining operations may also threaten removal of important geologic and engineering features before adequate base maps and surveyed control can be established. Maintaining such control during the mapping process is yet another complication. In addition, basic geometry yields nearly vertical outcrops. Access required for direct observation and measurement, essential to conventional plane table or Brunton techniques, may be impossible on such surfaces. Also, nearly vertical surfaces appear fore- shortened in plan view. This reduction in area provides little room for recording geotechnical detail. The difficulties encountered in open pit mapping can be substantially reduced by utilizing a modified form of plane table photogrammetry. This technique employs photographs taken from the ground as the base upon which details are recorded. The information is later transferred to plan maps using the plane table principal of location by intersection (Davis and Foote, 1953). Any change in topography can be accommodated by simply taking additional photographs. Proper spatial representation in plan view can be determined later when updated maps and surveyed control are available. In addition, horizontal photographs from the ground portray vertical surfaces as they are normally viewed thus providing maximum area for recording details. Any detail which can be identified on the photograph can be located correctly even though the actual feature is physically inaccessible. The technique presented in this paper was developed by the author for special applications at Kennecott's Bingham operation in 1970. The procedure was rapidly adopted for general use and has proven to be a practical tool for detailed investigation of potentially unstable areas (Zavodni and McCarter, 1976) and routine geological mapping (Richardson, 1975). Major advantages, other than those mentioned above, include: The speed and accuracy are greater than for conventional plane table or Brunton methods. The photo- graph represents a view from a station at some distance from the area being mapped. This vantage point allows evaluation of possible continuity of structures from one level to another which may not be evident at close range. The photographic base provides a permanent record of the topography at the time

Jan 1, 1977

By Michael Karmis, Emily A. Sarver, Ellen S. Gilliland, Leigh-Anne H. Krometis

"Public engagement is increasingly important in ensuring the success of projects related to energy development, particularly with regard to issues of environmental protection, public health, and socio-economic impacts. This is due to concurrent trends in public behavior, including a rise in public interest in these projects that is not matched by a rise in science literacy, and increasing organization and participation of the public through social media, citizen science, and grassroots initiatives. In recent years, several high-profile incidents have demonstrated that when public concern is ignored or met with a passive response from industry, it can rapidly grow into organized opposition that negatively impacts or wholly derails a project. Engaging, listening to, and educating stakeholders during early planning and development phases are therefore essential to earning credibility and trust. Moreover, maintaining two-way lines of communication throughout the lifespan of a project demonstrates social responsibility and facilitates cooperation, acceptance, and even support from communities and others. Positive experiences with specific projects at a local, community level can influence the larger public opinion of an entire industry sector. This paper presents cases studies of public engagement related to shale gas development (including hydraulic fracturing and pipeline construction), mountaintop removal mining, and management of mixed-use watersheds near surface mining operations. The experiences highlighted in these case studies are used to draw best practices of public engagement for sustainable energy development.Introduction Within the scientific research community, the importance of public engagement has gained increasing recognition. In a 2007 article in Nature, medical researcher, Patrick Taylor, stated that public engagement has both “gone viral” and “gone global” and has the ability to make real impacts to research (Taylor 2007). Nancy Baron, the science outreach director for COMPASS, an organization providing communications training for scientists, provides further evidence for the increasing focus on engagement, including shifting attitudes observed during her own experience as a communications coach and documented in surveys, the recent inclusion of communication and engagement activities in academic tenure review, and the surge of workshops, materials, and other resources available on the subject (Baron 2016). In addition to COMPASS, a number of organizations and institutes have been developed to train scientists for communication and engagement with the public, perhaps most notably the Alan Alda Center for Communicating Science at Stony Brook University, and academic fellowship programs, such as the Leopold Leadership Program at Stanford University and the Wilburforce Fellowship Program, have been established for the same purpose."

Jan 1, 2017

By A. L. Boerner

Off-highway tire costs represent a significant portion of the total mining costs in openpit, truck-shovel operations. To extend the lives of tires, the site-specific factors influencing tire life should be investigated Valuable data can be obtained by combining historical operational data captured by a mine dispatch system with detailed tire and maintenance histories. Assuming that failure counts satisfy a Poisson distribution, F-tests can be applied to determine significant deviations from desired or target counts. The methodology developed in this paper can be used to identify the haul routes and loading and dumping zones that have significantly higher incidences of tire failure. Corrective action can then be targeted at these zones by modifying the shovel or truck operator practices; changing the haul route maintenance and clean up practices; or altering the bench, ramp or waste dump design parameters. An example is given of the correlation of tire separation and tire impact failures with haul routes for a fleet of nine Caterpillar 793C trucks in operation at the Chuquicamata Mine in northern Chile. A high incidence of impact failures was observed for the ex pit ore crusher and for tires installed in the left outer rear position on the trucks. The latter was postulated to be due to a preference for drivers to execute right-hand turns prior to dumping. Recommendations were made to revise crusher and dump cleanup practices and investigate the feasibility of super-elevating the surface of dumping zones to reduce ground pressure on the left rear tires.

Jan 1, 2002

By Ronald J. Searle, Howard S. Latham

In April 1964 the Bureau of Reclamation awarded the first contract for rapid machine excavation of a water conveyance tunnel . Since then the Bureau has excavated seven tunnels with a total length of over 190,000 feet utilizing rapid excavation tunneling machines. Tunnel bored diameters have varied from 9' 0" to 20' 10" (See Table #1) and tunnel lengths from 5,000 feet to 67,000 feet. Driver and cutter units varied from 43 rolling teeth and eight rolling discs mounted on a rotating head driven by five 200 HP 23,000 volt electric motors to 20 discs and one tricone unit mounted on a rotating head driven by two 100 HP 440 volt motors. All tunnels were driven with a laser beam guidance system governing both line and grade. Trailing conveyors and rail haulage systems were used to dispose of the excavated material. Approved Bureau of Mines diesel locomotive engines for waste trains were prevalent power sources supplemented by battery units on some projects. Sandstone, conglomerates, agglomerates, siltstone, shale, and granite were the geological formations encountered, with sandstone and shale the preponderant material . Tunnel support systems utilized were structural steel ribs; rock bolts and metal plates; and shotcrete, or combinations of these. Progress varied from 51-1/2 feet to 154 feet per working day for three shifts, depending on rock material and supports required. One contractor established a record rate of advance of over 400 feet in one day, 1,905 feet in one week, and 6,848 feet in one month. Such diversified experience in underground machine excavation methods presented an excellent opportunity to observe, analyze, and evaluate associated environmental health problems. Also, to develop measures for controlling

Jan 1, 1997

By H. J. Chen, Y. Luo, S. S. Peng

Surface subsidence resulting from underground coal mining can cause problems for buried pipelines. In this paper, a technique for assessing the level of stress on a subsidence-affected pipeline is introduced. The main contributors to the stress are identified, and mitigation techniques for reducing the stress are proposed. The proposed mitigation techniques were then successfully tested.

Jan 1, 1998

By Barry J. Hansen, Ruston A. Ford

Production of mine backfill from the tailings produced in a proposed Crandon concentrator is described. A process has been developed capable of producing suitable fill for the mining method selected for the Crandon orebody. It maximizes the placement of pyrite underground as fill and segregates tailings into pyrite and nonsulfide fractions. To determine the suitability and engineering characteristics of the backfill product for use underground, laboratory and physical stope simulation model testing was conducted. The results of the testing and the application of those results to the design of the backfill system ultimately affecting mine geometry and subsequent mine production will be presented.

Jan 1, 1981

By V. Galla

In the present paper, two large diameter columns 2 m tall and 1.3 m diameter filled with crushed (finer) and run off mine (coarser) heap leach materials respectively were used to perform unsaturated flow studies. Instruments measuring moisture content and matric suction were placed in the columns at different depths as water was applied at calibrated flow rates from the top of the columns. The outflows from the columns were recorded using tipping bucket rain gauge placed at the bottom of the columns. Unsaturated hydraulic parameters were also obtained for the heap leach materials, scalped (passing 4.75 mm sieve size) and whole (passing 37.5 mm sieve size) sample. The measurements obtained from the columns were later compared with unsaturated flow modeling results. The comparison indicated sensitivity towards the sample size selection for unsaturated hydraulic parameters, and initial conditions considered in the model.

Jan 1, 2009

By E. Watkins, R. Kimutis, H. Dougherty

Gas wells have often intersected mining resources, but unconventional shale well drilling has more recently challenged mines to balance the risk of interaction due to higher pressures and larger quantities of gas. Full extraction mining, such as the longwall method, induces ground movement that may influence the casings if wells are drilled within the mining area. The possibility of a casing shear would lead to the risk of unplanned gas migration into the mine. This has the potential to quickly overcome the ventilation system and reach the explosive range which, if ignited, can have catastrophic consequences on the health and safety of underground workers. The utilization of network software to model mine ventilation is a common practice in the mining industry and can assist with a well breach scenario. This work focuses on a well breach in between two longwall panels after second panel mining with gas entering primarily through the gobs of the adjacent longwall panels. Applying the network software Ventsim, a gob zone and ventilation network were created to better understand the distribution of gas within the mine and the limitations and effectiveness of a ventilation system. The model shows both a transient flow simulation and steady state concentrations throughout the mine ventilation system. Using a standard Pittsburgh coal seam longwall ventilation scheme, we find that the system can dilute a significant inflow of up to 700 cfm of methane.

Mar 2, 2022

By Chris C. Sundberg, Ronald E. Heuer, Stanley L. Paul, Peter M. Douglass

Use of prestressed concrete cylinder pipe (PCCP) for pressure tunnel liners is gaining popularity with contractors, engineers, and owners. This paper presents loading considerations and a beam-spring computer model approach to tunnel liner analysis, together with ultimate strength (US) and service load (SL) procedures for liner design. The US procedure is best suited to check for adequate liner strength under extreme loading conditions. The SL procedure, based on conventional pipeline design practice, is considered more appropriate when addressing crack control and serviceability under normal working load conditions. Other design and construction considerations are discussed and a design example is presented.

Jan 1, 1987

By E. B. Johnson, G. Kjerbol, L. J. Holloway

The Mount Baker Ridge Tunnel is a major improvement of Interstate Route 90 in the State of Washington. The total length of planned underground construction is about 3,400 feet (1,040 m) of which 1,332 feet (406 m) will be constructed by a stacked-drift tunneling method. Sized for vehicular traffic on two levels, the net interior diameter will be 63 feet (19.2 m) requiring an exterior diameter of about 80 feet (24.4 m). The material to be excavated is predominantly stiff clay, and this will be the largest-diameter tunnel ever attempted in soft ground. A construction contract for the stacked-drift tunnel was awarded in late 1982.

Jan 1, 1983

By D. K. Grubbs

Anorthosite is an abundant, domestic source of alumina with reserves in individual deposits ranging from a few billion to hundreds of billions of tons. While anorthosite contains less alumina than does kaolinite, its CaO and Na20 contents are significantly higher (Figure 1). Alumina can be produced from anorthosite by alkaline, soda-lime sinter or acid processes. CaO and Na20 are advantageous because they are reactants consumed in alkaline processes. Acid processes require high calcium plagioclase feldspars (bytownite-anorthite) to obtain high alumina extraction because the lower calcium plagioclase feldspars (andesine-labradorite) are not as readily dissolved during digestion. The layered Raggedy Mountain Gabbro group in the Wichita complex in southwest Oklahoma is a high calcium anorthosite that could be processed by acid, sinter, or alkaline methods. Chemical grade limestone in the Arbuckle Group is located within 45 km of the anorthosite (Figure 2).

Jan 1, 1980

By J. N. Adamson

The Alcan Smelter project at Lynemouth on the Northumbrian coast draws cooling water for the power station through shafts and tunnels from the North Sea. The sea at this part of the coast is frequently very rough and even in calm weather the coastal currents are strong. The adjacent coal mine makes use of these currents to disperse colliery waste and discharges into the sea some thirty thousand tons each week. In consequence the sea bed is continuously shifting and the sea is black and turbid. Construction of sea shafts under these conditions presents difficulties as drilling from a floating vessel is hazardous and sea bed activity of divers is greatly hindered by the entire absence of visibility. After considering several alternatives a method of construction was agreed with the Consultants in which the drilling and also the lining of the shaft would be completed in sequence from an eight legged work barge (GEM 126). Each shaft would be drilled to full depth and a steel cylinder, with its ends closed temporarily, would be lowered into the hole and grouted into the formation to form a full-length permanent lining. The bell mouth for each shaft would be constructed in advance to form part of the cylindrical casing. On interception of the shaft by its appropriate tunnel the lower end of the cylindrical casing would be cut away and the internal walling of the shaft installed from below. After completion of construction the shafts and tunnels would be flooded and the bell mouth sealing covers removed by divers.

Jan 1, 1997

By O. R. Swendseid

The Mountain Con mine is a relatively old, deep mine located in Butte, Montana. Operations at this property through the present shaft were started before the turn of the century. As mining progressed to depth, increasing demand for ventilation facilities and changing mining conditions made it convenient to convert some nearby shafts to airways. The fact that these openings had not been originally planned for use as airways made it necessary in some instances to utilize long and inefficient already-estab¬lished entries to service working areas. This situation existed in the Lexington fresh air system. The Lexington system consists of a vertical, 3-compartment shaft extending from surface to the 3200 level and a series of 2-compartment air raises and old horizontal-haulage openings extending into a mining area several thousand feet west of the Lexington shaft between the 3900 level and the 4200 level. Because of restrictions and high resistance in the portion of the system between the bottom of the Lexington shaft on the 3200 and the mining area on the 3900, the capacity of this system is only 85,000 cubic feet of air per minute. It was calculated that the capacity of the system could be in¬creased to meet the demands of the current mining program in this section of the mine by utilizing a single, straight, horizontal air course on the 3200 and by driving an inclined air raise 740 feet long between the 3900 and the 3200.

Jan 1, 1967

By J. West-Hansen

The problem of long-term production scheduling in an underground coal mine is approached through the concepts of sequencing theory. Based on a typical layout of mining sections, the principles for the approach are: 1. The definition of mining sections as jobs, and mining methods as machines. 2. The reduction of the overall mining activity to the general problem of nonpreemptive scheduling of precedence related jobs on parallel machines. 3. The simplification of the layout to a general type directed network with the nodes representing jobs and the arcs representing precedence relations. 4. The determination of a feasible and near-optimal job schedule given the objective of maximizing the total net present value of the jobs. A general scheduling heuristic is being developed for implementation on an IBM personal computer (PC) as part of an interactive computer system for long-term production planning.

Jan 1, 1986

By Paul L. Russell, Charles O. Hook

While the oil shale resources of the US are becoming increasingly known, few people in this country are aware of the extensive worldwide occurrence of this resource. Two recent international conferences* confirmed the growing worldwide interest in oil shales, both as future and current energy sources. The 1981 conference noted the difficulty in characterizing worldwide oil shale resources because of lack of common terminology in reporting both assay value and resource potential. Assay value is variously reported as: •US gallons per short ton; •Imperial gallons per metric ton; •Liters per metric ton; •Liters per cubic meter; •Weight percent oil; and •Volume percent oil. Oil shale resources are variously reported in barrels, short tons of oil shale, metric tons of oil shale, and cubic meters of shale oil. Worldwide petroleum shortages sparked interest in alternate energy resources including oil shales. While petroleum supplies appear to have stabilized, at least for a while, high costs are affecting the balance of payment index of many countries, resulting in a continued search for local energy resources. Kerogen is the organic constituent of oil shale and may be the most abundant form of hydrocarbon on earth, possibly exceeding coal occurrences and far more abundant than naturally-occurring petroleum resources. Oil shale, by one name or another, is widespread and is known to exist in more than 38 countries (Table 1). Oil shale industries have existed in at least 14 countries at one time or another. Many predated the Drake oil discovery in Pennsylvania in 1859, and most were unable to compete with natural oil; these operations either converted to its use or closed. At the present time shale oil is being produced on a commercial scale only in the USSR and in China. Only very rough estimates of grade and quantity are available for most of the worldwide shale occurrences since only a few deposits have been thoroughly explored. The Green River Formation of Colorado, Utah, and Wyoming is an exception. For many years this oil shale deposit has been described as the largest single concentration of hydrocarbon material in the world. With increasing world interest, larger deposits may yet be found. In 1965, the US Geological Survey published an in-place world oil shale estimate. This study, while made some 16 years ago, is still a reasonable order-of-magnitude estimate. Although exploration and evaluation are underway and a few oil shale deposits have been appraised, information on which to evaluate most worldwide oil shale occurrences has improved little since 1965. Table 2 presents an order-ofmagnitude estimate of in-place world oil shale resources. Total US resources and Green River Formation

Jan 1, 1982

By P. C. Schutte, A. J. Kielblock

INTRODUCTION Certain activities, such as emergency work and rescue operations, often have to be undertaken in environments where heat loads often exceed limits prescribed for routine work. This is particularly relevant to the South African mining industry where heat stress-induced fatalities are not uncommon during rescue operations. In this regard an excessively hot environment is defined as one where either the dry-bulb temperature exceeds 37,0°C or the wet-bulb temperature exceeds 32,5"C, and it is therefore not surprising that heat stroke mortality escalates rapidly when these limits are exceeded. A review of both local and international standards indicated that the available information on safe exposure times under abnormal heat stress conditions is very limited. Where available, such standards are aimed at the general population, including both sexes, irrespective of age and also the least heat tolerant worker, and not at a medically-screened, all-male population free of grossly heat intolerant individuals, as is the case in the South African mining industry. It is suggested that available norms and limits are too conservative for local application and, therefore, unrealistic. In view of the definite need to protect workers when exposed to abnormally high environmental temperatures, the present study was undertaken to establish a scientifically derived data base. applicable to local conditions, to determine safe exposure times: Any exposure limit, especially in an emergency situation, should be easy to administer, valid and reliable. These aspects, there- fore, form an integral part of this paper. FORMULATION OF HEAT STRESS LIMITS The formulation of heat stress limits was based on the criterion that a heat exposed individual should experience a negligible risk of developing dangerously elevated body temperatures. In order to provide a database for risk assessment, certain physiological responses of heat tolerant men were determined at various combinations of thermal conditions and work rate in a climatic chamber. These physiological responses were analysed statistically in order to predict safe survival and tolerance times as a function of thermal conditions and work rate. EXPERIMENTAL DESIGN A total of 202 randomly selected, medically fit mine workers volunteered for the study on the basis of informed consent. These men were considered to be inherently heat tolerant in as far as they had successfully completed a heat tolerance test (Anon., 1991) or the standard climatic room acclimatisation procedure used on many South African gold mines (Anon., 1989). The subjects were allocated randomly to 14 experimental groups and each group was exposed in a climatic room to one of

Jan 1, 1997

By R. A. Lowe

Smectite is a common impurity in the kaolins of Georgia. This impurity is harmful to the low-shear rheology of kaolin slurries in concentrations as low as a few weight percent. The deleterious effect of smectite on the low-shear rheology is due to the swelling of the mineral. Montmorillonite containing clays were treated to precipitate a compact brucite layer {Mg(OH)2} in the interlayer region of the expandable layer silicate mineral. This treatment forms a hydroxy-Mg-montmorillonite with characteristics similar to chlorite. This treatment effectively reduces the swelling capacity of the mineral and improves the rheological properties of kaolin slurries contaminated with smectite impurities.

Jan 1, 1999

By Steven A. Elmquist

Although past investigations (2, 5)have been conducted to determine crushing relationships, no program which covered a broad range of crushing conditions had been conducted. The previous studies appear to concentrate on small segments of the overall picture and did not fullfill our desired information objectives. The Crusher Variables Research Program conducted at the Mineral Research and Test Center (MRTC) of Rexnord, due to the broad range of variables utilized in a production size crusher, is believed to be the most comprehensive study of its kind as of this date. The principles developed by the Symons brothers in 1925, when they patented the cone crusher as we know it today, are still being used in the machine known as the Symons Cone Crusher, During the development of this novel crushing concept, a technique known as the fall of material (called the Bouncing Ball Theory1 by some) was used to determine an idea as to the proper head angle, eccentric and speed of eccentric rotation, The final variables used for the Symons Cone Crusher design were, therefore, the logical conditions to start with and use as a reference against which other variables could be compared.

Jan 1, 1979

By J. Drelich, J. D. Miller

The wetting behavior of liquid polymers at solid surfaces and the adhesion forces involved at polymer-filler interfaces should always be considered in the preparation of high-quality polymer composites, including those made with mineral fillers. Spontaneous polymer spreading over the filler surface is a basic condition for the design of polymer-mineral composites. In this regard, the wetting and adhesion characteristics of polymer-mineral systems are reviewed. Based on this review it is clear that several aspects of wetting phenomena at mineral filler surfaces require further systematic study. Specifically, efforts should be made to determine the wetting characteristics of molten polymers at mineral-filler surfaces in greater detail. Also, the effects of mineral-surface contamination (including surface hydration) on wetting and adhesion phenomena need specific investigation. It is expected that an improved fundamental understanding of wetting and adhesion phenomena for polymer-mineral composites will provide the basis for further technological development.

Jan 1, 1996