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By E. Watkins, M. B. Daza

Although there have been great advances regarding the understanding of mine fires in underground mines in the last century, fires remain high risk incidents. During fire scenarios, many crucial decisions and actions can be made that greatly influence the outcomes of these scenarios. Underground worker decisions are mainly based on training and experience, which in some cases can be complemented with previous analysis of fire effects. In order to review the guidelines that should be taken into account for this kind of examination, a numerical analysis of effects produced by a shuttle car fire under five different ventilation conditions was carried out. The analysis provides some insightful recommendations for firefighting personnel such as time for direct attack and best attack position for first responders and fire brigade groups. Also, the most critical parameters for each scenario were determined. Finally, all results were systematically organized and a first approximation of a fire classification based on the tenability limits was provided for first responder and fire brigade groups. The methodology used in this study for the fire classification could allow for the most appropriate decisions by firefighting personnel increasing the probability to put fires out without compromising their health and safety. INTRODUCTION While there have been great advances regarding the causes of mine fires in underground mines in the last century “small fires have occurred and always will occur in underground mines” (Conti, Chasko, Wiehagen, & Lazzara, 2005). The response time and decisions made during an underground mine fire are critical elements that have direct influence on the event outcome. Mine fires can grow in size quickly causing catastrophic consequences, thus rapid and suitable response actions can result in the difference between an minor emergency situation and a disaster. Upon the confirmation of a fire, a decision must be made regarding whether to fight the fire or evacuate the mine. Even though all underground coal mines possess emergency response plans and firefighting personnel are highly trained, decisions can be complemented with previous numerical analyses. Such analyses could contribute with the knowledge of potential fire effects and consequently with fire preparedness in the mine. Preparedness in underground mines is an important element to reduce the probability of the negative consequences of a mine fire. The time elapsed between the detection of the fire and response in the early stage is a serious component since small fires can produce larger and more serious consequences. If a mine fire cannot be put out within the short time after discovery, the chance of getting the system back in balanced or the success of safely controlling and extinguishing a mine fire is reduced (Conti et al., 2005, Conti, Chasko, Wiehagen, & Lazzara, 2000, Trevits, Yuan, Teacoach, Valoski, & Urosek, 2009, Brake, 2013). As confirmed by Conti and others, if a mine fire cannot be controlled by direct firefighting methods the probability of extinguishing the fire, without sealing is greatly reduced (Conti et al., 2005). However, response actions such as direct extinguishment must be carried out without compromising the health and safety of the firefighting personnel (Kim, Lönnermark, & Ingason, 2010).

Jan 1, 2019

By G. T. Lineberry

Reduced clearance is one of the most important characteristics of encumbered space in underground coal mining. Another key variable is the maximum velocity at which a piece of mobile mining equipment can operate in this limited space. Typical velocity- clearance curves for different mine transportation systems are developed and characterized. Applications of the relationships are examined, emphasizing their significance in the design and control of mine materials handling systems.

Jan 1, 1983

By Paul Javor

Optimization of a process is achieved by selecting, 'from all the known options, the most beneficial method of obtaining a product. It is rare that the optimum process is arrived at by conventional methods, because of the great amount of time required for developing and comparing all the options. On the other hand, it is now possible, by means of an optimization program based on special mathematical formulas involving an algorithm and implemented by a computer, to plot the optimum process realizing considerable savings and in a reasonably short time. The flow sheet arrived at in accordance with the optimization program described in this paper investigates and develops all the possible options and, with the aid of the computer, makes it possible to select the most economical ore beneficiation process. The options in an ore beneficiation process are all the possible trajectories that can be traced through the particle sizes to which the ore is reducible in the extraction of its valuable minerals. Although an ore can have a wide range of composition and several valuable minerals that can be extracted, this paper is concerned with the special case in which only one mineral is extracted from the ore and in which the maximum allowable percentage of impurities in the end product is defined.

Jan 1, 1971

By Atmesh K. Sinha

The demand for thermal coal both nationally and internationally is projected to increase rapidly. The marketability of high ETU thermal coal produced in the USA is, however, limited by its high sulfur content. Fortunately, over 70 percent of the sulfur exists in pyritic form. The research conducted at Southern Illinois University indicates that over 90 percent of the pyrite can be removed by simple devices such as concentrating tables, cyclones, or froth flotation cells and the desulfurized coal can be blended with low sulfur western coal to produce EPA compliance coal. Thus, both the low BTU western coal and the high sulfur midwestern coal can be rendered competitive in the utility markets, here and abroad due to improved utilization.

Jan 1, 1983

By C. A. Fleming, C. J. Ferron, P. T. O'Kane, D. B. Dreisinger

The platinum group metals (PGM's) are typically recovered by flotation, smelting of the flotation concentrate to matte, and matte leaching. Concentrates too low grade to be processed economically by the conventional process require a new treatment route. PLATSOL, a new pressure leach process, was developed for the Northmet deposit and dissolves in one step base and precious metals (PGM's and gold). Various options exist to recover all pay metals from the leach liquor. The preferred option to date involves a solid-liquid separation, followed by sulphide precipitation of gold and the PGM's, and copper solvent extraction using commercial solvent extractants. This paper briefly summarises the process and the effect of the main leach parameters. Application of the PLATSOL process to various feedstocks is also presented.

Jan 1, 2000

By J. H. Daniel

Dust-related respiratory disease remains the major health concern in mining, and health agencies are proposing more stringent standards. The U.S. Bureau of Mines (USBM) is investigating techniques to continuously monitor respirable dust in real-time during the coal or ore extraction process. Continuous monitoring will allow mine operators to evaluate hazardous dust concentrations and adjust the operations to produce less dust. Mine instrumentation applications include machine-mounted and hand-held monitors, personal monitors, and area/environmental monitors. Six dust detection methods have been considered to meet application requirements. These are: light-scattering instruments, a smoke-particle detection technique, correlation of pressure drop across the collection filter with amount of dust deposited, the Tapered-Element Oscillating Microbalance (TEOM) instrument, a method that relates the amount of dust collected on a filter with the vibration of the filter, and beta attenuation measurement of dust. Studies to date have identified the TEOM instrument and the technique of correlating the amount of dust collected with the vibration ofthe filter as having the most promise for success. Development of the machine-mounted monitor is the highest research priority. The application options and progress to date in developing continuous monitoring instrumentation are presented.

Jan 1, 1995

By J. Hanna, I. Anazia

Selective fatty acid flotation of carbonate gangue from sedimentary apatites was achieved under acidic pHs without a specific apatite depressant and without conditioning the pulp with the collector. Concentrates (35% to 38% P2O5, 0.8% to 1% MgO) with high recoveries (80% to 85%) were produced from Indian and Chinese dolomitic ores. The calcareous and/or dolomitic-siliceous phosphate ores of South Florida and Utah required two flotation stages: one for carbonate removal, as mentioned above, and the other for phosphate recovery from siliceous gangue. Preliminary tests on the South Florida ore gave concentrates analyzing 29% P2O5 and 0.8% MgO, with a P2O5 recovery of 76%. A concentrate obtained from the western US phosphate ore from Utah assayed 30% P2O5 and about 1% MgO, with a P2O5 recovery of 89%.

Jan 1, 1988

By V. Matthews

"INTRODUCTION Typical grinding electrification requirements are defined by high power, constant torque and slow speed. Dual pinion mills also include a need for tight tolerances in torque between the two motors, to avoid overloading any single motor. Standard induction (asynchronous) motors have often been used but only in combination with mechanical gearboxes (reducers), required to reduce process speed to the correct level for mill pinions. The gearbox introduces added system complexity, capital cost, maintenance and energy cost due to mechanical losses. SYNCHRONOUS AND ASYNCHRONOUS MOTORS Elimination of the gearbox requires a motor designed to operate at a very low speed (rpm). Traditionally, mill motor requirements were best served by synchronous motors. The benefits of synchronous motors include- • Higher Efficiency (no conductor losses in rotor) • Very high power at low speed • Flexible Power factor (leading or lagging) • Constant speed (not load dependent) • More accurate speed control Synchronous motor cost is higher due to construction complexity, need for exciter and excitation panel, brushes, brush lifters. Figure 1 represents the equivalent circuit for a synchronous motor.Asynchronous motors, also known as squirrel cage induction motors, are singly excited, per Figure 2, the resulting equivalency circuit is less complex and only in need of a single voltage source.Commonly, a DC voltage supply is connected to the rotor (both physically and electrically) via brushes. The DC voltage enables the production of flux in a single direction. The brushes are connected to rings. The slip rings encircle the rotor but are insulated from the rotor. The slip rings are connected to a rotor winding known as a field winding. On large motors, brushless exciters are often used. A brushless exciter is a small AC generator whose field circuits are mounted on the stator and armature circuits are mounted on the rotor shaft. The exciter generator’s 3-phase output is rectified to DC by a 3-phase rectifier (mounted on the shaft) and fed into the main DC field circuit. It is possible to adjust the field current on the main machine by controlling the small DC field current of the exciter generator (located on the stator). [1] Brushless synchronous motors are often preferred over the traditional brush design but introduce additional complexity to motor construction in the form of additional windings and rectifiers comprising the excitation circuit. It stands to reason that because of the additional complexity, a synchronous motor will be higher in cost than an equally rated asynchronous induction machine."

Jan 1, 2015

By M. E. Orman

Many factors must be considered when designing a heap leach pad. Geotechnical properties of the ore, can and will affect how well an ore leaches, the solution recovery, stability of the heap, and settlement. As a heap is stacked some of these properties will change due to the increased load. In order to properly design a heap these properties should be determined beforehand so that the heap performs as intended.

Jan 1, 1997

In the estimation of recoverable resources, geostatistical techniques such as Multiple Indicator Kriging require a change of support correction to derive theoretical recoveries based on an assumed level of mining selectivity. The change of support models most widely used in practice entail model based generalized corrections either on a global or local basis. Examples include the affine and indirect lognormal methods. Change of support corrections derived empirically through short-scale conditional simulation realizations often show notable differences compared with theoretical corrections determined using model variogram parameters. The existing changes of support models are reviewed and an alternative method is proposed.

Jan 1, 1999

By William G. Pariseau

The purpose of this paper is to present a design procedure for the quantitative estimation of support load requirements in underground mines. Emphasis is upon the basic features of support behavior common to a large variety of support systems-bolts, timber sets, stope fill, steel arches, concrete liners and so forth. A strong reliance is placed upon fundamental principles and modern computing techniques for their quantitative implementation. Example problems illustrate the approach. Where artificial support is required, the ground in the vicinity of the face usually stands unsupported long enough for the support to be installed. At the time of installation, the load transferred to the support from the adjacent rock is essentially zero, although in some cases there may be an initial set load, for example, from timber blocking. With the passage of time and advance of the face, ground motion loads the supports. If the support system is properly designed, then the additional loading poses no threat to the safety and productivity of operations. If not, then difficulties may arise including high maintenance costs, hazardous work conditions and reduced productivity. Of course, over-design can be equally wasteful. Quantitative estimation of support loads is therefore essential to overall efficiency in mining.

Jan 1, 1975

By W. B. Hayes

The origin of the titanium pigment and metal? industries began with the discovery of the element titanium in 1791 by an Anglican clergyman named William Gregor. The titanium was discovered in magnetic black sands found in the beaches near Cornwall. England. The name titanium was established by the German chemist who discovered the mineral rutile in Hungary. Rutile is the oxide of the element titanium, which he called titan alluding to the mythological titans, giants of ancient Greece. The commercialization of titanium minerals began probably in 1916 with the production of titanium tetrachloride which was to be used in tracer bullets, flares and smoke screens during World War 1. In the 1920's composite pigments based on TiO2 barium sulfate and calcium sulfate were produced, followed by the introduction of the sulfate process anatase TiO2 crystal in the 1930s. The U.S. Bureau of Mines in 1938 began investigating titanium metal technology and promoted the development of the Kroll process. which is the magnesium metal reduction of titanium tetrachloride to produce titanium metal sponge.

Jan 1, 1989

By R. M. Von Storch

Most coal mining areas of the Western United States are characterized either by thick beds, steep pitches or heavy cover. Individually, each of these may present inherent safety hazards that influence miring. When all are met at one location, the combined effect is to make the safe operation of the mining property a challenge to management. These combined, conditions are met in most coal mines in southeastern Utah including those of the United States Steel Corporation. This coal bed measures up to 16 feet in thickness, the pitch is as much as 25% and mining is under a cover approaching 2, 000 feet. The Sunnyside coal bed is found in the Book Cliff Mountains, a great escarpment extending from west of Castle Gate, Utah, some 180 miles to Grand Junction, Colorado. West of Green River, Utah, the Book Cliffs swing sharply to the north because of the domelike uplift of the San Rafael Swell to the southwest..It is in this northerly extension of the Book Cliffs that the Sunnyside coal in the Blackhawk Formation of the Mesa Verde Group, Upper Cretaceous Age is found. The strata are transected by numerous faults with from a few inches to as much as a hundred feet of displacement. All of these faults have had some effect on the mining operation, either in roof control or, in the case of major faulting, the pattern of mine development.

Jan 1, 1967

By John Drew Ridge

Recent work by Haas has made available information on densities and vapor pressures of solutions of differing salinities at temperatures up to 330°C. From these data it is possible to predict the behavior of volcanic exhalations of various degrees of salinity as they approach the sea floor. Particular attention is devoted to solutions of 5.0 weight per cent NaCl and 20 weight per cent NaCl, two fluids that approximate quite closely the salinities of what Roedder termed: (1) normal hydrothermal fluids and (2) fluids typical of stratiform deposits of low-temperature conditions of origin. It is apparent that solutions above 220-230°C. cannot reach a sea floor on which the depth of water is 600 feet or less in the liquid state but will boil at some appreciable depth beneath the sea floor. Such boiling would result in the precipitation of all constituents of the ore fluids of significantly lower vapor pressure than water. The principal such constituent would be salt, and no sulfide deposits, the major constituent of which is salt are known. It follows, therefore, that ore fluids probably never get close to the sea floor of shallow seas at temperatures high enough to permit boiling. Ore fluids significantly above 230°C. can reach the sea floor in the fluid state only if the depth of the sea in the area. in question is well above 600 feet, for example, solutions at temperatures of ±300°C. reach the sea floor in the liquid state only if the depth of sea water is slightly over 3000 feet. Ore fluids reaching the sea floor at such depths may be the parents of such fluids as the Red and Salton Sea brines. On the basis of these data, the Cyprus and Kuroko deposits are discussed.

Jan 1, 1973

By R. Pandey, G. Elie, E. Sarver

Respirable crystalline silica (RCS) is generally considered the most hazardous constituent of coal mine dust, and a new federal rule is expected to further limit exposures in U.S. mines. For regulatory purposes, RCS is monitored by collecting filter samples, which are analyzed for quartz (the predominant form of RCS in coal mines). The analysis is done using Fourier transform infrared spectroscopy (FTIR) in a centralized laboratory. To enable more timely results, National Institute for Occupational Safety and Health (NIOSH) mining researchers developed a directon- filter (DOF) FTIR analysis method and free FAST software that can be used in the field. For samples collected under specific conditions, FAST processes the FTIR spectral data to determine quartz mass. While the DOF FTIR method is not approved for regulatory RCS monitoring, it could be useful for engineering purposes, such as to evaluate mining parameters or new dust controls. This field study demonstrates how the method, including FAST, can be applied using low-cost, widely available sampling components. It further demonstrates how quartz percentage can be estimated in the field, by pairing a continuous personal dust monitor with a filter sampler.

Jun 1, 2025

By B. Devulapalli

A mathematical model of the industrial hydrocyclone based on fluid dynamics is a better alternative to the currently existing empirical models. The swirling-flow velocities are determined by solving the Navier-Stokes equations with an appropriate turbulence model. The solution of the momentum-balance equations yields the flow field inside the hydrocyclone which determines the particle trajectories, and subsequently the classification curve. The essence of the model is that the physical dimensions of the hydrocyclone and the slurry characteristics can be incorporated, and the influence of these parameters reflects on the flow predictions. The predicted tangential and axial velocities in a 250-mm hydrocyclone are in good agreement with the laser-Doppler velocimetry measurements. Finally, the predicted classification curves show good agreement with experimental data measured on a KREBS Dl0B hydrocyclone.

Jan 1, 1993

By M. A. Gibson

Ilmenite-rich lunar deposits can be converted to liquid oxygen to support lunar base operations and space transportation propulsion needs by a Carbotek-developed process. Iron oxide in ilmenite is reduced at elevated temperatures by hydrogen in a fluidized-bed reactor to water vapor which is electrolyzed to product oxygen and recycle hydrogen. Reaction rate, thermodynamic equilibrium, and lunar-gravity fluidization behavior are key factors which have been considered. Fluid-solids behavior has been modeled from data taken at lunar gravity conditions aboard NASA KC-135 flights. Large-scale pilot plant operations are planned to complete the development.

Jan 1, 1991

By Joseph Renk, David Akers, Glenn Shirey

Each year, US coal cleaning plants landfill or impound millions of tons of high-quality, fine-sized coal. This coal is not only difficult and expensive to capture during cleaning, but, if captured, can pose serious materials handling problems. The GranuFlow. Technology was developed and patented by the U.S. Department of Energy (DOE) to address these problems. GranuFlow involves the addition of a coal binding agent such as an asphalt or heavy oil emulsion to coal to reduce moisture, dusting, and freezing and to improve the flow properties of the coal in bins and chutes (1, 2, and 3). When the emulsion is added before mechanical dewatering, the binding agent causes the formation of fine-sized coal agglomerates that dewater better than untreated coal. In addition, the binding agent increases the capture of ultra-fine coal in screen-bowl centrifuges. Previous work by DOE has also demonstrated that such treatment results in a significant reduction in dustiness and a reduced potential to freeze. To address concerns about the handling and combustion characteristics of GranuFlow treated coal, DOE performed a pilot-scale pulverization and combustion test (4). No problems were encountered during pulverization or combustion, and use of this fuel in a p.c. boiler was found to be feasible from a technical perspective. CQ Inc. has an exclusive license from DOE to market this technology and is currently performing a series of commercial demonstrations to determine if GranuFlow is both technically and economically viable.

Jan 1, 2005

By J. D. Miller, C. L. Lin

Liberation of valuable minerals during size reduction is an important aspect of mineral processing technology. In practice, most quantitative information on liberation is based on the application of stereological theorems for the analysis of image data from two-dimensional polished sections. On this basis an estimate of the volumetric grade distribution is made. Recently, a new method based on cone-beam xray microtomography has been used for direct determination of the three-dimensional liberation spectrum of multiphase particles 100 microns in size or less. Preliminary results for a packed bed of particles indicate that high spatial resolution (approximately 15 microns) and the direct processing of raw volumetric data are two important benefits offered by this new method. Three dimensional liberation analysis by microtomography provides an excellent opportunity to overcome many of the limitations of currently used polished section techniques. For example, detailed textural information is provided. Of course microtomography provides an independent method to verify current procedures used for analysis and transformation of polished section data into an estimate of the volumetric grade distribution. More important, however, is the possibility that this method could be developed as a routine procedure for liberation analysis in the 21st century.

Jan 1, 1997

By I. Iwasaki

As the world tension relaxes and as the interest and taste for consumer products change, complacency is beginning to prevail over the needs of minerals and primary metals. The current trend towards resources and energy conservation calls for miniaturization of consumer goods, and lowers the demand for virgin materials to produce goods and services. Challenged by the third world countries with high grade ores and low labor costs, industrialized nations with lower grade ores are being pressed into more efficient operation through technological innovation, while protecting the environment. In many countries, domestic mines were forced to close since the oil crises due to rapidly rising energy and labor costs. Research in conventional mineral processing needs to be directed towards breakthrough technologies in order to maintain the competitive edge in the global marketplace. Research activities will provide new challenges in the processing of solid waste and waste water for environmental remediation as well as for resource conservation, in the preparation of new functional materials of extreme purity and/or unique properties for high technology applications and in the development of such future resources as deep sea minerals and extraterrestrial materials.

Jan 1, 1995