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By Stephen L. Chryssoulis

The detection and quantification of invisible gold by microbeam techniques is discussed. Ion probe microanalysis is used to quantify the gold content of individual sulphide, sulpharsenide and oxide particles with a detection limit of 0.2 ppmw (g/t). The proton microprobe is used to determine the gold concentration of gangue minerals with a detection limit of 2 - 4 ppm. Using these techniques complete mineralogical balances for gold are obtained to assist in the process selection and optimization. A total of twenty gold and gold-bearing ores have been examined. Selected examples are presented.

Jan 1, 1990

By John J. Dwyer

As one begins to contemplate the organization of a talk with the title "Iron Ore - The Permanent State of Evolution," the main divisions appear to be the past, the present, and the future. But distaste for repetition of the present production achievements, which scarcely need additional description on this occasion, soon leads one to the conclusion that a more appropriate division of the subject is simply the past and the future . . . with emphasis on the future. We are working in the present, but it can only be understood by what has taken place in the years and decades gone by, and/or under what terms we will have to face the future. Evolution is more often thought of as a steady change - but steady change is really the product of revolutions, sometimes making headlines but often unnoticed at the time. With hindsight, we recognize the great importance of the emergence of the Bessemer converter and the open hearth and the vast influence that both have had on steel making and the changing ore demand. In this country we also see schooners opening the era for lake transportation of iron ore from Michigan to Take Erie. Later, steamships haul the ore from the Mesabi Range to the steel centers of the country. In order to take full advantage of the inland seaway, there had to be revolutions in ship design, loading and unloading facilities and channel and lock development. Full scale utilization of the resources of the Mesabi Range, itself, required parallel upheavals such as the development of new production equipment, and substitution of modern forms of energy for horsepower, and, yes, manpower, as well.

Jan 1, 1968

By Raymond E. Langen

Uranium exploration in the Powder River Basin of northeastern Wyoming has been intensive since 1966 and in 1968 produced significant discoveries of reduced uranium ore by Humble Oil & Refining Company and others. Substantial reserves have been established in the area. High-grade carnotite ore was discovered in 1951 near Pumpkin Buttes in the central part of the basin (Fig. 1). Other mineralized areas were soon established from Pumpkin Buttes south to Monument Hill and Box Creek. Total production from these shallow oxidized deposits in the lower Eocene Wasatch formation was small. The AEC reports total production of 520,000 tons of ore averaging 0.19% U3O8. The authors are indebted to many people within Humble Oil & Refining Company and Esso Production Research Company for their assistance and guidance. SUMMARY AND CONCLUSIONS The Highland ore deposit, discovered in 1968, is a large uranium occurrence located in the southern part of the Powder River Basin. Uranium mineralization consists of sooty, black uraninite and coffinite coating sand grains and is concentrated along the margins of Tertiary fluvial sandstones. Uranium was transported by oxidizing solutions roving through the buried sandstones and spreading into less permeable channel-edge sandstones to form typical rolls and tabular deposits. Unaltered sandstones are light gray to gray-buff where the sandstones have been oxidized, the colors are various shades of red, yellow, and yellowish brown. An Oligocene tuffaceous source for the uranium is proposed; however, leaching of the arkosic and tuffaceous host sediments may also have provided a source.

Jan 1, 1971

By Adam Levy, Thomas Novak, Sampurna Arya, Joseph Sottile, Kozo Saito

The use of a woven wire-mesh screen as part of a flooded-bed dust-scrubbing system is popular in the underground coal mining industry. It is used in combination with a demister (mist eliminator) to remove dust from the dust-laden air. A study was conducted to measure the pressure drop across a flooded-bed, wire-mesh screen at different airflow rates in one-phase (dry) and two-phase (wet) conditions. Two empirical relationships between pressure drop and air velocity were developed for dry and wet conditions, respectively. In both cases, the form of the empirical relationships was found to be similar to relationships given by Sabri Ergun for high velocity, non-Darcy, single- and multi-phase flow through porous media. The experiments were repeated on a reduced-scale model of the wire-mesh screen, and the pressure-velocity relationships obtained from the full-scale prototype experiments were tested. The test results show validation of the full-scale empirical formulae on the small-scale model with an insignificant variation. This paper presents the empirical equations for pressure drop across the wire-mesh screen in dry and wet conditions. Researchers can use these equations as a tool to predict total pressure drops for wire-mesh screens of different scale sizes.

By R. R. Klimpel

In this first report, we present a preliminary model based on the simple binary sys¬tem of component B occluded in a matrix of compo¬nent A, for the case where fracture planes can pass with equal ease through A or B. By assuming that the volume fraction of B in AB in the overall matrix is small, which is realistic for many prac¬tical systems, the problem is reduced to a one-¬dimensional treatment which is conceptually easy to understand. The model was programmed for Monte Carlo simulation, and an analytical solution also developed based on the assumption of zero or one mineral fragment per particle. Preliminary ex¬perimental confirmation using a synthetic "mineral¬-host matrix" of known amount and size of B in AB is presented.

Jan 1, 1983

By Terry S. Maley

With some exceptions, minerals may be acquired on the unappropriated public lands by one of three methods: (1) mining claim location under the General Mining Law of 1872; (2) mineral lease under the Mineral Leasing Act of 1920; and (3) sale contract under the Mineral Materials Act of 1947. Leasable minerals such as oil, gas, coal and phosphate are specifically designated as leasable in the Mineral Leasing Act so the method of acquisition is clear. As a general rule, metallic minerals are acquired by mining claim location. However the nonmetallic minerals, most of which are industrial minerals or gemstones, present a more difficult problem. These minerals are acquired either by mining claim or a sale contract depending on their chemical composition, physical properties and the use to which they are put. The Act of July 23, 1955 (30 U.S.C. 61 1) provided that uncommon varieties of sand, stone, gravel, pumice, pumicite or cinders are locatable; whereas, common varieties of such minerals may only be acquired by a contract of sale. The widespread location of mining claims to appropriate such deposits has caused many land management problems. Federal court and Interior decisions offer the most useful guidelines in determining the most appropriate method of acquisition.

Jan 1, 1991

By E. C. Roper

Landusky Mining, Inc. and Zortman Mining, Inc. are two registered Montana Corporations wholly owned by Pegasus Gold, Ltd. of Vancouver, B.C. The Zortman and Landusky Mines are located in the Little Rockies District of central Montana. The Zortman-Landusky mines produced 2,100 kg gold in 1982. A total of 3,250,000 t of ore per year are mined during the period March 1, to September 15, at an average grade of 1.04 gm/t (0.03 oz/t) gold and 13.4 gm/t (0.385 oz/t) silver at a cutoff grade of 0.35 grams of gold/ton (0.01 oz of Au/t) of ore. The stripping ratio during 1983 is anticipated to be 0.75/1 waste to ore. Combined average plant capacity of the two Merrill-Crowe plants is 9,840 lpm (2,600 gpm). The combined heap spray capacity of the two plants approaches 18,900 lpm (5,000 gpm). The mine employs approximately 200 people, about half of these work for the mining companies and the other half for the mining contractor, N. A. Degerstrom of Spokane, Washington. Net profit in 1982 for Zortman and Landusky Mining, Inc. approximated $4,900,000 at an average gold price of $11.40/gm.

Jan 1, 1983

By William C. Howe

This paper describes the technical status of the atmospheric pressure fluidized bed combustion (AFBC) process for utility steam generation. Major areas where AFBC development work is needed are discussed. Various approaches to solving these key issues are identified and the ongoing research and development programs addressing the key development areas are described. Other significant programs pertaining to the development of AFBC for utility steam generation are also discussed and needs for future work identified.

Jan 1, 1978

By LeRoy D. Loy

The coal mining industry must be able to compete with alternate sources of fuel for the utility and industrial customers. If the industry is unable to control transportation costs, either due to government interference, or for other reasons, then mining costs must be kept down. Australia, South Africa, Canada, (and later Colombia) will take larger shares of the export market if mining costs are not kept competitive. The government's environmental regulations must be met without incremental increases in mining costs. Entrepreneurial instincts must be retained by the industry to provide for their investment in the future. What are the Problems with Existing Research? Government funding for coal mining research has been reduced or virtually eliminated. BCR (Bituminous Coal Research) is now a membership- supported organization, but its primary focus has been on health and safety-oriented research. BCR, however, is now attempting to widen its scope and conduct other types of research. There are almost no funds in EPRI's (Electric Power Research Institute) program for coal mining research. Large mining companies do some research for their own purposes and needs, but this is proprietary and therefore results are not shared with the remainder of the industry. The mining industry as a unit is not undertaking productivity (systems) oriented research in any common or cohesive manner.

Jan 1, 1983

By Liming Yuan, Wei Tang, RICHARD THOMAS, DAVOOD BAHRAMI

The location and orientation of fire suppression nozzles is critical in suppressing mobile mine equipment fires. To effectively suppress such fires, optimization needs to be considered for the suppression nozzle locations and discharge angle. Detailed experiments were conducted to study the effectiveness of fire suppression agents with different nozzle configurations. A variety of fire suppression systems including dry chemical, wet chemical, dual agent (dry and wet chemical), carbon dioxide, and water mist were used. Six types of nozzle locations were studied, and their fire suppression effectiveness were compared. Results from this work highlight potential considerations when determining effective fire suppression designs.

Feb 1, 2025

By James J. Meadows, Jason D. Pampena, Emanuele G. Cauda, Lauren G. Chubb

Respirable crystalline silica (RCS) found in dust generated by various mining processes is an important occupational hazard in the underground coal-mining industry. Exposure can lead to disabling and incurable diseases, including coal workers’ pneumoconiosis (CWP), silicosis and lung cancer [1,2]. Clusters of rapidly progressive CWP have been observed in the Appalachian regions of eastern Kentucky and southwestern Virginia, and recent cases have been generally more severe and showing more rapid progression. CWP is approximately four times as common among long-tenured underground coal miners in central Appalachia than long-tenured underground miners in the rest of the United States, and 20.6 percent of long-tenured underground miners in central Appalachia were suffering from the disease as of 2017.

By M. A. Sochocky

Rod mills were developed, as a logical substitute for the rolls crusher when larger tonnages had to be handled, on a continuous basis. Today, with even larger tonnages to process, the trend is to install larger equipment, automate the plant and develop the highest availability possible, in order to cut costs. The rod mills, because of design limitations in size and speed 1'2, are not able to meet these new requirements. The autogenous mill was a timely development and serves as an excellent alternative for ores that are suitable to this type of grinding. When ores are not amenable to autogenous grinding, selection of a flowsheet is dictated by liberation characteristics and unit operations to be used for mineral recovery.. The following alternatives are available: (a) Multiple rod mills, capable of drawing no more than 2000 HP each, followed by ball mills. (b) Gyradisc crusher followed by two stages of ball mill grinding.3 (c) Tertiary crushing followed by closed circuit single stage ball mills grinding to approximately -100 mesh, as in the copper industry. (d) Tertiary' crushing followed by two-stage, ball milling. Each stage will operate in closed circuit with either screens or cyclones. It is this last alternative, particularly as it

Jan 1, 1972

By John A. Dearinger, Fred D. Wright, Robert C. Howell

INTRODUCTION The rock mechanics study of the shortwall mining system at Beth-Elkhorn corporation's Hendrix No. 22 Mine is being conducted under contract with the U.S. Bureau of Mines. The objective of the study is to obtain data on surface subsidence over a portion of the mined area, strata subsidence in the mined area, and underground stress changes and displacements in and near natural support elements of the mining system. This study is currently in progress, and only a portion of the results are being presented at this time. The Hendrix No. 22 Mine is located in the moderately rough mountainous terrain of Letcher County in eastern Kentucky. The nearest mine workings to the shortwall area are approximately 1,900 feet distant. The depth of cover over the mined shortwall area varies from 770 feet at Panel 1 to 170 feet at Panel 5 (Figure 1). The strata in the shortwall area is summarized in the three core logs shown in Figure 2. Hole no. 2 is located in approximately the center of the mined shortwall area (Panel 3, Line C, Figure 1). The coal seam in the shortwall area is approximately 4 feet thick and horizontal, although one major ‘roll’ intersects all panels.

Jan 1, 1977

By David G. Chedgy

It is probably safe to assume that most operating personnel working in coal preparation plants are exposed to noise levels in excess of the MESA Noise Regulations unless they are wearing ear protection. The excessive in-plant noise levels have received little attention until recently. Noise control has not been an important design consideration in existing coal preparation plants. This situation is rapidly changing as plant owners and plant operators are requiring that new coal preparation plants be designed to provide a safe noise environment for operating personnel and also meet MESA Noise Regulations. This paper discusses the noise exposure hazards, noise generating mechanisms, and some possible noise control solutions for typical coal preparation plants.

Jan 1, 1975

By I. Weir-Jones

[Currently the cost of carrying out 'in situ' geotechnical investigation programmes or installing and operating monitoring systems at construction or mining sites is rising var." rapidly. This is primarily because of our ever increasing labour rates. As a result of this problem efforts are no,, being made develop techniques for the economical; collection of large quantities of geotechnical data relating, to such problems as done stability evaluation, the behaviour of underground openings, or 'in situ' testing procedures. The efforts to reduce the labour content. are particularly apparent in those procedures which have traditionally been manpower intensive e.g. 'in situ' permeability testing where an entire drilling crew and their associated eguipment have been on standby while testis has been carried out; or data collection in underground construction operations where much tine is typically wasted obtaining or maintaining access to instrument sites. In an attempt to illustrate one specialist consulting company's approach to the problem of reducing investigation costs, this rarer examines four recent developments in the field of geotechnical investigation and monitoring which have come about during the last two Years as a result of cur research and development programme. Although these techniques and devices have been developed for specific projects, they all have broad applications in the geotechnical field and they are indicative of the direction in which this company feels developments will take place.]

Jan 1, 1975

By P. T. Bissert, T. J. Lutz, J. A. Yonkey, G. T. Homce

"Underground refuge alternatives require an air source to supply breathable air to the occupants. This requires pressure relief valves to prevent unsafe pressures from building up within the refuge alternative. The U.S. Mine Safety and Health Administration (MSHA) mandates that pressure relief valves prevent pressure from exceeding 1.25 kPa (0.18 psi), or as specified by the manufacturer, above mine atmospheric pressure when a fan or compressor is used for the air supply. The U.S. National Institute for Occupational Safety and Health (NIOSH) tested a variety of pressure relief valves using an instrumented test fixture consisting of data acquisition equipment, a centrifugal blower, ductwork and various sensors to determine if the subject pressure relief valves meet the MSHA requirement. Relief pressures and flow characteristics, including opening pressure and flow rate, were measured for five different pressure relief valves under a variety of conditions. The subject pressure relief valves included two off-theshelf modified check valves, two check valves used in MSHA-approved built-in-place refuge alternatives, and a commercially available valve that was designed for a steel refuge alternative and is currently being used in some built-in-place refuge alternatives. The test results showed relief pressures ranging from 0.20 to 1.53 kPa (0.03 to 0.22 psi) and flow rates up to 19.3 m3/ min (683 scfm). As tested, some of the pressure relief valves did not meet the 1.25 kPa (0.18 psi) relief specification.IntroductionThe Mine Improvement and New Emergency Response Act of 2006 (MINER Act) was enacted in the United States in the wake of three mine explosions/fires that claimed 19 lives that year. Intended to help improve underground coal mine accident preparedness, the MINER Act includes provisions that target mine safety issues in areas such as emergency response planning, adoption of new technology, training and education, and mine safety standards enforcement (U.S. Mine Safety and Health Administration, MSHA, 2006). Section 13 of the MINER Act specifically directed the U.S. National Institute for Occupational Safety and Health (NIOSH) to provide for research into the effectiveness and viability of refuge alternatives for underground coal mines. This mandate culminated in the 2009 adoption of changes to Title 30 of the Code of Federal Regulations (30 CFR) mining health and safety regulations, requiring underground coal mines to provide mine emergency refuge alternatives and associated components, to provide a life-sustaining environment for persons trapped underground. Such refuge alternatives can be either self-contained mobile units or built-inplace facilities. The regulatory changes also include provisions establishing requirements for MSHA approval of refuge alternatives and their components, and among these provisions are numerous criteria for providing a safe breathable atmosphere under positive pressure within the refuge alternatives. One specific criterion for maintaining a safe refuge alternative atmosphere requires the inclusion of an air pressure relief valve that will activate at a maximum of 1.25 kPa (0.18 psi), or at a pressure above mine atmospheric pressure, in the refuge alternative, as specified by the manufacturer when the breathable air is supplied by a fan or compressor (MSHA, 2008)."

Jan 3, 2018

By BERND SCHÖNHERR, JÖRG DEHNERT, PETER WINDISCH, JENS STOPP

The Quick-Erect Stopping System (QESS) offers a new way of reducing the radon exposure of miners in Germany, especially during remediation work in old mines. The QESS is a lightweight, modular and reusable construction kit of interlocking telescopic aluminum tubes, radon-proof foil and expanding foam. It is designed to seal off radon-rich parts of galleries within minutes. Originally, the QESS was developed to protect miners against radon exposure. Then, the QESS found the attention of several mine rescue teams at a German mining conference. Some mine rescue drills by The Student Mine Rescue of the Technical University Bergakademie Freiberg, Wismut Mine Rescue and Front Range Mine Rescue helped to improve the system and highlighted its potential for mine rescue operations. Now, the QESS is well-suited for small-scale mining. The QESS can be used to both protect miners from radon exposure and to support mine rescue operations. Moreover, the QESS was also successfully used in ventilation experiments.

By M. T. Atwood

For more than sixty years the rich oil shale formations of Colorado, Utah and Wyoming have been evaluated as a future source of petroleum. After many false starts the commercial production of shale oil is near. Union Oil and Colony (Exxon and Tosco) have begun construction of commercial plants. Occidental and Rio Blanco (Gulf and Standard of Indiana) are well along in the development of modified in situ (underground) processes. A number of other companies and groups are in advanced stages of development. This paper will review some of the major elements involved in the production of shale oil with emphasis on means available to express the efficiency of production of pyrolysis liquids and gases from oil shale rock.

Jan 1, 1982

By Ching-Yi Tsai

The effect of various constituents on the pyrolysis and combustion of a pulverized coal in an entrained-flow reactor has been inves¬tigated. Predicted time-temperature histories of the coal' particles and experimental weight loss data indicate a strong coupling of heat and mass transfer to the pyrolysis and combustion rates. A higher combustion rate following ignition was observed as particle size was increased to 112 µm. This is related to a higher particle temperature after ignition for the larger particles. Although the heating rate prior to ignition decreases with increasing particle size, higher slip velocities and surrounding gas temperatures for the larger particles promote early ignition. The presence of liptinite in the coal increases the weight loss rate before and immediately after ignition. Similar behavior was observed for pyrolysis. Fractions of a HVA bituminous coal which were rich in mineral matter or semi-fusinite were found to have a higher heterogeneous char combustion rate than vitrinite rich samples.

Jan 1, 1984

By Y. Luo

"Investigating abandoned mine subsidence is often a difficult task because many factors, both mining- and nonmining-related, can affect the possibility and the formation process of surface subsidence events over abandoned underground room-and-pillar mines. Among them, mine water frequently plays an important role in causing such subsidence events. However, mine water could also serve the purpose of preventing subsidence. The dewatering of abandoned room-and-pillar mines has been identified as the main cause for a number of serious mine subsidence events in the past.In this work, the mechanism of mine water to prevent surface subsidence over abandoned room-and-pillar coal mines was studied. Two mathematical models are proposed to quantify the potential effects of mine water on the structural stability of mine pillars, roof and floor as well as the potential for causing surface subsidence. The models are validated with an actual case. IntroductionThe potential for room-and-pillar mining operations to induce surface subsidence is mainly dependent on the recovery ratio in the underground mines that directly relates to the stability of pillars. Normally, if the recovery ratio is less than 50 percent, the mine pillars are sufficient to support the overburden strata without their collapse in a sufficiently large contiguous area. Consequently, there will be no surface subsidence. However, if the recovery ratio is greater than 70 percent, the pillars are too small to support the overburden strata and can cause immediate surface subsidence. In 1993, a mathematical model and program was developed and proposed (Luo and Peng, 1993) to predict surface subsidence caused by high-extraction, roomand- pillar mining. When the recovery ratio is between 50 and 70 percent, the mine pillars could be loaded near their critical condition and, therefore, the surface subsidence is uncertain to develop. If the surface subsidence did not occur immediately, mine water starts to fill the underground openings. If thick, clay-type rock layers are presented in the mine roof, floor or pillars, they can be considerably weakened by mine water and cause surface subsidence. The techniques to investigate subsidence events over inactive room-and-pillar coal mines caused by the weakening effects of raising mine water to the claystone immediate roof and floor were presented in Luo (2009, 2011)."

Jan 6, 2018