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By Philip Lindstrom

Retreat mining, using yielding steel friction props, over a seven-year period has been successful at a uranium mine operated by Hecla Mining Company in southeast Utah. The support system allow good roof control, maximum profit, complete extraction, and good ventilation. Unusual subsidence observations were made in that some of the surface was raised rather than lowered, Longwall mining, commonly practiced in European coal mines, has a potential of broader application because of mechanization possibilities and better roof control and ventilation at greater depths.

Jan 1, 1964

By Robert G. Moorhead

Fine-coal screening can be one of the most critical operations in a modern coal-cleaning plant. The yield and quality of clean coal produced in fine-coal circuits is controlled as much by how efficiently 0.15 mm (100 mesh) particles are sized as on the performance traits of the fine-coal cleaning device itself. In addition, the increased interest in effective fine-coal sizing operations indicates that many operators have also discovered its importance in affecting the quality and yield of clean coal produced in fine-coal circuits. This paper describes the three most prevalently used fine-coal screening technologies and discusses their sizing mechanism, performance, and application.

Jan 1, 1988

By C. Patrick

Annually, the US coal industry generates and must dispose of over 200 million st (180 million t) of coal refuse, expanding a major environmental problem. The purpose of this research was to investigate the feasibility of utilizing coal refuse as an aggregate in concrete. This paper reports on findings of the initial phases of a project to determine the viability of replacing traditional concrete blocks with refuse blocks for use in ventilation stoppings in underground mines. Refuse, collected from three active preparation plants in eastern Kentucky, was used as the primary as aggregate in the preparation of concrete cylinder. Stress-strain analyses on the refuse cylinders yielded compressive strengths of from 59% to 77 % of the control-group strengths. Low variability within the groups was found while significant differences between the groups existed. On-going determinations of the effects of weathering on the refuse cylinders is being conducted and will be completed in early 1995. The research results are favorable for the future direction of the overall project objectives.

Jan 1, 1997

By V. K. Paruchuri, J. D. Miller, J. Nalaskowski

An understanding of forces responsible for the stability of dispersions of colloidal particles when interacting with each other in aqueous solutions is of great interest academically and industrially. When water-soluble polymers are adsorbed onto colloidal particles, various effects on the stability of their suspensions can be expected ranging from steric stabilization to bridging flocculation. The possibility of detailed characterization of such systems using direct measurements of interaction forces between particles can help in further improvement of existing technologies of solid-liquid separation. An atomic force microscope (AFM) colloidal probe was used to measure the interaction forces between a silica sphere and a silica substrate in the presence of water-soluble polymers. Poly(ethlene oxide) (PEO) with three different molecular weights (7,000, 43,000, and 63,000), each with a very narrow molecular weight distribution, were used in this study. The interaction forces measured with the AFM over an extended time scale are discussed in terms of the adsorption kinetics measured through in-situ FTIR/IRS measurements.

Jan 1, 2003

By Allan M. Johnson

Since 1974 researchers at Michigan Technological University have been studying mine subsidence in the Iron River District of Northern Michigan. The district, which was active from 1881-1978, has had numerous cases of subsidence. Much of the subsidence resulted from rock mass failure but some appeared to have developed primarily in the thick glacial overburden which is a typical feature of this area. This latter observation led to the recognition that some of the surface subsidence was due to piping; i .e., loss of overburden material to the mine voids by groundwater flow (Johnson and Frantti, 1978). The Sherwood Mine was the last mine to operate in the district. With its closedown scheduled for late summer of 1978, a unique opportunity to monitor the mine as it flooded was presented. It was reasoned that with the cessation of pumping, groundwater would rise in the overburden and the mine would flood. The physical characteristics of the mine were favorable for piping to occur as the mine flooded. With the permission of Inland Steel Mining Company and the support of the U. S. Bureau of Mines, a project to monitor the Sherwood Mine for piping subsidence began in June of 1978. This paper present aspects of this study pertinent to the piping-induced subsidence events which occurred at the Sherwood Mine in 1980 and 1981, including acoustic emission monitoring of the subsidence activity, hydrologic monitoring of the groundwater regime and the flooding mine, laboratory modeling of the piping mechanism, and analytic procedures which are under development.

Jan 1, 1982

By Arpad E. Torma

The introduction of biotechnological principles in hydrometallurgy has created new opportunities and challenges for the industry of mineral processing. During the 1950's and 608s, the mining wastes and unused complex mineral resources have been successfully treated in bacterial assisted heap and dump leaching processes, especially for the production of copper and uranium. The economic viability of bio- leaching technology lead to its world-wide acceptance by the mining industries. During the 1970's this technology grew into a more structured discipline which is called "biohydrometallurgy". Currently, bioleaching techniques are ready to be used, in addition to copper and uranium, for the extraction of cobalt, nickel, zinc, gold and silver from diverse mineral resources and for the desulfurization of certain coals. However, in a foreseeable future the biohydrometallurgical processes may be applied also for the treatment of high- grade ores and mineral concentrates using native and/or genetically engineered microorganisms.

Jan 1, 1989

By B. DANIEL MARJAVAARA, I. A. SOFIA LARSSON, ANNA-LENA LJUNG

One way to upgrade iron ore is to process it into pellets. The pelletizing process is multifaceted, involving complex fluid dynamics with highly turbulent, high-temperature flow in intricate geometries. This makes it hard to perform measurements during operation, so a useful tool for better process understanding is computational fluid dynamics (CFD), where the challenge is to perform efficient and trustful simulations of complicated problems. A validated simulation model can be valuable for increased process control and development. In this paper, the flow field and coal combustion process in a pilot-scale iron-ore pelletizing kiln is simulated using a CFD model. The objective of this work is to apply a coal combustion model to enable an investigation of thermal effects from the flame on the surrounding flow field.

By K. C. Shaver

Detailed examination of the Sloan Ranch diamond prospect has shown that the Sloan 1 diatreme, the Sloan 2 dike, and the Sloan 3 horizontal sheet complex are all parts of the same kimberlite complex. Geologic mapping, geophysics, soil chemistry, test pitting, and drilling all helped to delineate the structure. Bulk sample testing yielded moderate grades with encouraging gem-to-industrial ratios, but no large stones were recovered. These test results, along with supporting mineral chemistry data, suggest that the Sloan Ranch complex is analogous to sub- economic occurrences located near the margins of the Archean cratons in southern Africa.

Jan 1, 1987

By W. N. McAnulty

Because so many interrelated technical, economic, legal and political factors are involved in evaluation of commercial mineral deposits, it is common practice today to assign such work to a team of specialists including geologists, mining engineers, metallurgists, lawyers, and economic evaluation experts. Each member of the team plays an important role; the role of the geologist is particularly important. The geologist involved with evaluation of fluorspar deposits needs all the geologic and economic training and experience required for evaluation of metallic mineral deposits. Few, if any, industrial or metallic minerals occur in so many geologic environments as fluorite. Fluorspar, and aggregate of rock and mineral matter containing enough fluorite to make a commercial deposit (ore), is somewhat more limited in its modes of occurrence than fluorite, but it too is found in a variety of environments.

Jan 1, 1970

By D. Bahrami, G. Danko

Spatial and temporal temperature and humidity variations for 5000 years are simulated in an emplacement airway within the conceptual, high-level nuclear waste repository proposed to be built at Yucca Mountain, Nevada. A multi-scale model is configured using MULTIFLUX, a thermohydrologic-ventilation code. The predicted surface temperature of most waste packages during post-closure exceed 140oC, the threshold limit known for likely localized corrosion for Alloy 22 waste package material. Small amounts of infiltration airflow through the mountain in Panel 5 are found to transport liquid water condensate to some of the waste packages emplaced along the peripheral section of the drift due to edge cooling.

Jan 1, 2004

By TUIJA MONONEN, LUDGER BENIGHAUS, VIRGINIA DEL RIO, CHRISTINA BENIGHAUS, SARI KAUPPI, JUHA M. KOTILAINEN, JAVIER GÓMEZ, JARI LYYTIMÄKI

This article presents results from a comparative case study focusing on newspaper coverage of mineral exploration and mining in three European countries representing different geological and socioeconomic contexts. The results show that regional newspapers in Finland, Germany and Spain report about mining issues relatively intensively even in the absence of major accidents or other media events causing peaks of attention. The tone of the articles is generally neutral to positive toward mining activities. Common themes include mining revival, mining events and social interaction, history of mining, and damages related to mining. Past, present and future employment opportunities related directly or indirectly to the mining sector are key storylines. Contrary to some expectations, the regional-level debate was not dominated by a long-lasting confrontation between the mining industry and its adversaries spearheaded by environmental nongovernmental organizations.

By W. S. Fyfe, G. Southam, T. J. Beveridge

Sporosarcina ureae was able to grow in the presence of tip to 10-ppm L-asparagine complexed gold. However, 10 ppm Au3+ was found to be highly toxic to Sporosarcina ureae, killing 109 bacteria/mL within a few seconds. To compare the effects of these responses on gold mobility, an in vitro bacterial biofilm model was developed to examine the interaction be¬tween Sporosarcina ureae and ionic gold or L-asparagine gold complexes in gravity fed columns. The immobilization of ionic gold was between 80% and 90% over a period of one week. But, as the available cellular reactive sites became saturated, immobilization decreased to 14% within two weeks. In the L¬asparagine-gold system, gold immobilization in the cytoplasm occurred at a high rate (80% to 90%) throughout the experi¬ment, with limited toxicity towards Sporosarcina ureae. The bacterial immobilization and detoxification of L-asparagine¬complexed ionic gold was associated with a low molecular weight, i.e, <5,000 dalton (atomic mass unit), intracellular protein fraction. This peptide-complexed gold would allow for the continued biogeochemical cycling of gold under ambient (<100°C) surface or near-surface conditions.

Jan 1, 2000

By Brian Fulcher

The Fort Lawton Parallel Tunnel was built in 1990 - 1991 by Morrison Knudsen Corporation (MK) as an integral part of Seattle METRO&apos;s planned expansion of the Westpoint Treatment Plant. The project included a concrete lined 2542 m (8,340 ft) long tunnel bored in sands and clays under the presence of methane gas and over 27.4 m (90 ft) of ground water table. The tunnel roughly paral¬lels an existing and still operating 3.65 m (12 ft) diameter tunnel originally completed in 1909. The parallel tunnel was constructed using a Lovat 4.72 m (15 ft-6 in) earth pressure balanced TBM with ribs and timber lagging as primary support. The tunnel alignment crossed under as much as 91.4 m (300 ft) of overburden as well as twin mainline railway tracks; terminating in a shaft adja¬cent to the Seattle ship canal. The project was completed in June, 1991 after a final "wet-tap" tie-in to the existing brick-lined sewer; over five months ahead of the contract schedule. This paper will describe the construction methods, job site conditions and difficulties encoun¬tered on this very challenging and successful project.

Jan 1, 1993

By C. D. Litton, I. E. Perera

This report presents the results of experiments to evaluate different types of mine fire sensors in an underground mine environment using a commercially available atmospheric monitoring system. To determine how well carbon monoxide (CO) and smoke sensors respond for purposes of fire detection, experiments were conducted using test fires of different mine combustibles and for both flaming and nonflaming combustion. The experiments were designed to assess the response of fire sensors to different contaminants and different contaminant levels produced from the test fires. The experiments were performed in the Safety Research Coal Mine at the U.S. National Institute for Occupational Safety and Health’s Bruceton Research Facility in the presence of an average ventilating air velocity of 1.6 m/s (315 fpm). Five fire sensor stations were located downstream of the test fire at fixed locations, with each sensor station consisting of four sensors: a CO fire sensor and three different smoke sensors, of which two were evaluated by the Mine Safety and Health Administration (MSHA) for intrinsic safety and the third was used extensively in underground mines overseas but not evaluated by MSHA for intrinsic safety. All four sensors were mounted near the center of the entry and in the upper onethird of the entry height. A UL-listed combination ionization and photoelectric smoke sensor was mounted near the roof at the first sensor station and its responses were compared against the responses of the four CO and smoke fire sensors. Sensor response data, contaminant travel times, and the impact of fire on the existing ventilation flow are discussed as they apply to earlywarning fire detection. Of significance in the analysis is the need for performance standards for mine fire sensors in order to provide for consistent and timely early warning of developing fires.

Jan 1, 2014

By William C. Ellis

Underground water is part of a continuing hydrologic cycle, which involves all elements of water occurrence. All groundwater of economic importance is in process of movement through a porous rock stratum from a place of intake or recharge to a place of disposal. Groundwater moves and is contained in fractures in the rock and/or in intergranular spaces of porous formations. Where there have been no water developments by man, groundwater is in a state of approximate equilibrium and the forces of replenishment and discharge are in balance. Thus, groundwater, unlike other mineral resources, is constantly being replenished in most areas at a rate which is measurable and which is important in the planning of its utilization. As illustrated by Figure 1, replenishment of groundwater supplies results from the direct penetration of rainfall through the soil to the water table, by seepage from surface streams or ponds, and/or by subsurface movement from an adjacent groundwater body. Under natural discharge conditions, water is commonly consumed by transpiration of trees and other types of vegetation, by flows from springs, by evaporation from shallow depths below the surface, and seepage into streams that traverse the area.

Jan 1, 1964

By Grover H. Emrich

Pennsylvania,, due to its location in the humid east, is fortunate to possess within its borders large quantities of water. Most of the State is drained by three major river systems-the Ohio, Susquehanna and Delaware. This abundant supply of surface water has been widely utilized throughout the State, but today other sources of water must be developed due to the increasing demands for water, die largest undeveloped source of water in Pennsylvania is ground water. Pennsylvania is also fortunate to possess extensive coal resources. These coal resources have contributed measurably to the development and prosperity of the States Coal and water&apos;s - two valuable resources - have been necessary for the development and industrialization of Pennsylvania, The State needs both resources but can no longer afford to develop one while adversely affecting or destroying the other, We are aware of the effect of coal mining on surface water, but coal mining can also materially affect subsurface water, This effect will according&apos; to the local geologic conditions.

Jan 1, 1965

By Dwayne K. Rowlett

A lysimeter designed to measure suction and collect a pore water sample from unsaturated waste rock has been developed and its performance has been verified in two large scale column tests. The test columns were constructed to bracket the envelope of grainsize curves for waste rock from Northern Saskatchewan. The suction profile within the columns was measured under a series of infiltration rates using tensiometers and these were compared to the lysimeter readings. The rate at which pore water samples could be collected was also measured under each infiltration rate. Lysimeter measurements of suction were found to be slightly lower than the tensiometers.

Jan 1, 2000

By Hajime Kitamura, Nobuharu Isago, Yuta Yamanishi, Kosuke Kawata, Hiroshi Yagi, Akira Matsuoka

Mountain tunnels are generally considered to be stable during earthquakes, however, it is known that the portal areas are prone to seismic damages. Characteristics in portals such as the location of the slope, modulus of ground deformation, and the change of overburden are different for each tunnel, and damage degrees are unclear. In this study, we reproduced the seismic behavior to investigate the effect on the tunnel portal by considering some parameters above, using simple static model tests and numerical analysis. As a result, the conditions of the slope condition and minimum distance from slope was confirmed to influence on the mechanical behavior of the tunnel portal during earthquakes.

Dec 1, 2022

By J. A. Marts, R. C. Gilmore, S. Saki, J. F. Brune

El modelamiento de la dinámica de fluidos computacional (CFD por sus siglas en inglés) implica la creación de un dominio de cálculo llamado malla o rejilla para resolver las ecuaciones que definen la física del flujo de fluidos. Este proceso comprende a menudo emplear la mayor parte del tiempo en esfuerzos de modelamiento. En un proyecto patrocinado por el Instituto Nacional de Seguridad y Salud Ocupacional (NIOSH), los investigadores de la Escuela de Minas de Colorado utilizaron un enfoque innovador de mallas, el cual permite una fácil adaptación del modelo CFD para adaptarse a una variedad de geometrías de minado de tajos largos ventilados por canales (bleeders) y progresivamente sellados (referidos a menudo como bleederless en los Estados Unidos), con la porosidad y la permeabilidad de la cámara escalables en un amplio intervalo. En este trabajo se presenta la metodología del enfoque de enmallado y escalado junto con las recomendaciones para el uso de modelos CFD en aplicaciones de ventilación para las cámaras en tajos largos. La nueva técnica de enmallado se utilizó para evaluar la función de un retorno hacia atrás en una cámara progresivamente sellada y otra cámara ventilada por canales.

Jan 1, 2014

By J. A. Marts, R. C. Gilmore, S. Saki, J. F. Brune

Computational fluid dynamics (CFD) modeling involves the creation of a computation domain called a mesh or grid to solve the equations defining the physics of fluid flow. This process often comprises the majority of time spent in modeling efforts. In a project sponsored by the U.S. National Institute for Occupational Safety and Health (NIOSH), researchers at the Colorado School of Mines used an innovative meshing approach, allowing easy adaptation of the CFD model to adjust to a variety of longwall bleeder-ventilated and progressively sealed (often referred to as bleederless in the United States) mining geometries, with gob porosity and permeability scalable over a wide range. This paper presents the methodology of the meshing and scaling approach along with recommendations for using CFD modeling in longwall gob ventilation applications. The new meshing technique was utilized to evaluate the function of a back return in a progressively sealed gob and a bleeder-ventilated gob.

Jan 1, 2014