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By C. Babbitt, J. O’Green, N. I. Jayaraman

In many mines, dust-laden air from an entry being driven by a continuous miner will contaminate the intake air to the roof bolter operator and other downwind personnel. Through a US Bureau of Mines (USBM) contract, Foster-Miller Inc. has evaluated several control techniques to reduce the respirable dust exposures of downwind personnel. One fan and tubing technique consisted of bypassing the miner-generated dust directly to the section return. The results of the evaluation of this technique revealed that reductions in dust concentrations of 90% or more can be achieved at downwind roof bolter locations. A second method was to clean the dusty air from the upwind continuous miner by using a dust collector. The cleaned air was then supplied to the bolter through collapsible tubing. An underground evaluation showed reductions of 82% to 96% when the dust collector was operating. A third method was to reduce the quantity of dust contributed by the miner to the return airstream. A water-powered scrubber was installed over the throat area of the continuous miner. More than 1.18 m3/s (2500 cfm) of dusty air moved through five tubes with dust collection efficiency exceeding 75%. Underground evaluation results showed that return dust concentrations were reduced by about 60%. This paper discusses the ventilation and dust control techniques used for personnel downwind of the continuous miner.

Jan 1, 1987

By J. W. Wilson, Y. Ding

In the ultrafine coal-cleaning process, small coal particles (-400 mesh) are produced during the pulverizing operation. After the coal-cleaning process, these ultrafine particles are very difficult to dewater and create problems in coal transportation, storage and handling at utility plants. Research on ultrafine coal dewatering and briquetting resulted in the development of a single-stage operation that is potentially more effective and economical than conventional thermal drying and briquetting processes. The final coal product has a moisture content of less than 15% and possesses high strength and water resistance that satisfies coal transportation, storage and handling requirements.

Jan 1, 1996

By R. Torbin

The degree to Which automation/remote control/robotics has been utilized in the mining industry is far less compared to general industry because of several factors. These factors include the adverse working environment, the difficult work operations, and the generally lower incentive for capital investments in new mining equipment. Foster-Killer has been actively involved in the development of advanced mining and underground construction equipment. This equipment is designed to be remotely operated to improve both productivity and worker safety. Many of these machines employ advanced electronics and robotic features. Other types of Foster-Miller developed robots will also be described Which could be applied to special mining problems. The types of machines that will be discussed include the following: remote shaft lining/placement. remote excavation/mining operations, automated conveyor system, and robotic surveillance.

Jan 1, 1989

By R. R. Klimpel

During the period of 1973-79, an extensive period of research and development was undertaken by Klimpel and coworkers (1980, 1981, 1982a, 1982b, 1983. 1984, 1987) on the identification of a commercially viable chemically assisted approach to improving the efficiency of the wet grinding of coals and ores in tumbling media mills. The emphasis of the previous publications just listed was on the engineering use implications of controlling-slurry viscosity (rheology) in laboratory and plant scale grinding devices. In this paper, some discussion and results pertaining to the actual chemical screening phase will be presented.

Jan 1, 1988

By Edgar E. Vidal, Patrick R. Taylor

Standard textbook equations for heterogeneous kinetics typically utilize a constant driving force to solve for rates and times of reactions. In order to more closely model real systems, equations and solutions are presented for particle leaching kinetics in which the driving force is decreased as the reactions proceeds. In addition, models for continuous co-current and continuous counter current aqueous-solid reactions are presented.

Jan 1, 2005

By Khosrow Bakhtar, Robert E. Cameron, Arfon H. Jones

The use of rock simulators in rock mechanics research greatly expands the scope of the problems that can be investigated with physical models. However, the exact reproduction of full scale conditions, or absolute simulitude, is not obtainable on a small scale model. For this to be possible, the scales of length, time, and pressure (or mass) must be changed without altering the theoretical equations that describe the behavior of materials concerned. In using rock simulants for physical modeling of structures designed in rock, the geometry of full scale structure is reduced to a size suitable for the available testing machine. This will require the strength related properties to be scaled down. Simulation should be representative of the in situ conditions. Complete simulation will require that friction parameters and the stress ratios be matched exactly between prototype and model. The procedure involved in application of physical modeling for rock mechanics research is discussed in the following pages. Background, theoretical approach, and anticipated benefits to the research community are also elaborated.

Jan 1, 1986

By Y. J. Wang

In the, mathematical analysis of electrical networks, the electrical devices are often modeled using idealized network elements such as current sources, voltage sources and resistors. An analogous approach is outlined for the modeling of mine ventilation networks, which can be considered nonlinear resistive networks. The proposed modeling technique uses the following five basic (nonreducible) elements: H, Q, D, R and N. These elements are characterized by their pressure gain or loss, their air quantity and their pressure-vs. -quantity relationships, each of which may be known or unknown. In addition to the definition of the basic elements, the necessary conditions for which there exists a unique solution are discussed This is performed using theoretical developments derived from electrical circuit theory and illustrated in example networks. The proposed procedures are useful in the solution and characterization of mine-ventilation networks.

Jan 1, 1997

The Mine Safety and Health Administration (MSHA) academy in Beckley, WV, received enquiries from various segments of the mining industry concerning alcohol and substance abuse in the mining industry. The MSHA Director formed a committee, the Mining Industry Committee on Substance Abuse (MICSA), to deal with these enquiries. The committee met in April 1985 at the mining academy in Beckley. The MICSA committee expanded its membership to represent labor, management, and government agencies affiliated with the mining industry as well as government agencies dealing with alcohol and drug abuse. This expanded 18-member committee met for the first time in July 1985. At that time, two cochairmen were elected, one from labor and one from management. MICSA has spent time on education by sharing information on the issues and by calling in outside experts for advice and consultation. The committee also initiated several projects. These include a resource manual on substance abuse and employee assistance programs. Mine operators and labor unions can use these programs as guides. MICSA is also assembling statistics on substance abuse, particularly as applied to mining. And the committee commissioned an Education film, Substance Abuse, Is It Our Problem? (The results of a survey on drug use, given in Table 1, suggest that substance abuse may indeed be a problem.) The educational film, produced by MSHA, is an introduction to the problem of substance abuse in the mining environment. The film encourages mine operators, labor unions, and miners to analyze their individual circumstances to determine whether a problem exists. The film also offers ways to deal with the problem. And the film invites the mining industry to request additional information from MICSA. There is no single approach to substance abuse that will fit the need of every mining operation. As with any health, safety, or production problem, remedies must be site specific. MICSA's aim is to channel ideas to those who seek to help employees in a mining environment who seek to rid themselves of alcohol and substance abuse. As stated more formally: The Mining Industry Committee on Substance Abuse represents the efforts of labor, management, and government. The mission of the committee is to make the mining industry aware of the problems resulting from alcohol and other drug abuse and to recommend possible methods to remedy the problem. The function of the committee is to assist the industry in developing programs and resources to recognize and provide help for troubled employees, and thus reduce the risk of accidents, while lower absenteeism and increasing productivity.

Jan 11, 1987

By Tracy T. Morris

The current state of the mining community has made it imperative for operations to reduce costs and increase productivity in order to remain competitive. This has been done in Colorado with the installation of an Outokumpu flash flotation machine for the production of a gold/silver/lead concentrate.

Jan 1, 1987

By D. J. Benton, S. Finley, D. T. Orr, A. J. Chambers, M. A. Stepan

"Corrosion of ground support can lead to falls of ground that pose a significant risk to miner safety. To address this problem, the National Institute for Occupational Safety and Health (NIOSH) is investigating corrosion at the Hecla Mining Company’s Greens Creek Mine, located near Juneau, Alaska, USA. Field studies have used photogrammetry surveys to document welded-wire mesh corrosion, and laboratory studies at NIOSH’s Spokane Mining Research Division (SMRD) have investigated the effects of corrosion on ground support integrity. Findings show that (1) corrosion monitoring through photogrammetric methods may be effective for qualitative measurements of welded-wire mesh corrosion, and (2) there is a relationship between loss of load-bearing capacity and the diameter loss due to corrosion in welded-wire mesh. Photogrammetry results thus far have measured an apparent bulking of the corroded welded-wire mesh, and preliminary laboratory tests have investigated the relationship between the larger bulked and effective wire diameter. If this relationship is verified, these results may indicate that photogrammetry, when combined with the models produced in laboratory tests, could offer a means of monitoring corrosion levels, as well as rock rib deformation. INTRODUCTION Reducing the number of rock fall injuries and fatalities is an important part of the mission of the National Institute for Occupational Safety and Health (NIOSH) Spokane Mining Research Division (SMRD). Ground control using support systems to protect miners from rock falls is one of the oldest mining sciences, and considerable research has led to a variety of modern tools and methods in use today. Among these tools are rock bolts and welded-wire mesh, which are made from increasingly higher-strength steel grades to meet the increasingly demanding requirements of underground mines [1]. However, the benefits of these higher-quality support elements may be negated in corrosive mining environments. A better understanding of how corrosion affects the support capacity of ground support systems will assist engineers in determining when an opening is at a greater risk of falls of ground. Accelerated corrosion has been occurring in some areas of the Hecla Mining Company’s Greens Creek Mine near Juneau, Alaska, USA. Corrosion of ground support has resulted in two falls of ground occurring between April 2015 and March 2016. While these falls of ground did not injure any personnel, mine management recognized the high risk to miner safety and responded by actively undertaking a ground support rehabilitation program. Rehabilitation measures include the installation of both galvanized and coated, corrosion-resistant bolts and welded-wire mesh, depending on local conditions."

Jan 1, 2017

By Michael P. Foose

In 1994, more than 41 of the approximately 160 coal-fired, electrical- power plants within the six-state Ohio River Valley region used flue-gas desulfurization (FGD) units to desulfurize their emissions, an approximately 100% increase over the number of plants using FGD units in 1989. This increase represents a trend that may continue with greater efforts to meet Federal Clean Air Act standards. Abundant limestone resources exist in the Ohio River Valley and are accessed by approximately 975 quarries. However, only 35 of these are believed to have supplied limestone for FGD electrical generating facilities. The locations of these limestone suppliers do not show a simple spatial correlation with FGD facilities, and the closest quarries are not being used in most cases. Thus, reduction in transportation costs may be possible in some cases. Most waste generated by FGD electrical-generating plants is not recycled. However, many FGD sites are relatively close to gypsum wallboard producers that may be able to process some of their waste.

Jan 1, 1999

By G. Atesok, M. S. Celik, G. Onal, I. Yildirim

A new coarse cleaning device, the Stripa, has been developed for processing of coal in the size range of -100+10 mm. The Stripa is an auotogenous heavy medium separator originally developed for processing of iron ores. Although it has been employed in concentrating ores such as chromite, it has not been applied in coal cleaning. In this study, a pilot plant scale modified Stripa and its counterpart alternative, a diaphragm jig, are compared using subbituminous and lignitic coals. The separation performance of the Stripa and the diaphragm jig has been established in the light of washability properties of the coal samples. Comparison of the performance of the Stripa with that of the jig indicates that the Stripa can be used in coal preparation circuits as an alternative to jigs in the size range of -100+10 mm. Simplicity, low initial investment, and low operating and maintenance costs make the Stripa a plausible candidate for coarse coal cleaning. More importantly, Stripa due to its short residence time, has a superior capacity over jig.

Jan 1, 1995

By Kostas Fytas, Sebastien Perreault

This paper presents EOLAVAL, an integrated mine ventilation design software. In its new expanded version it is a user friendly and fully interactive computer package. The features of the new version are a graphics interface fully compatible with Autocad files, an integrated database of fan characteristics and the optional use of the thermodynamic approach in carrying out network simulations. This software can be used in underground mine ventilation planning: mine ventilation network analysis and simulation, economic design of airways, auxiliary ventilation design, calculation of a mine air heating plant, and evaluation of the natural ventilation and pressure losses in a mine shaft. This paper presents a case study illustrating the use of the computer package in mine ventilation design.

Jan 1, 2002

By L. A. Morley, S. C. Gambrell

Behavior of a jour-leg shield design used on a soft floor in an operating longwall system is presented. The shield examined in this study was constructed having a split base and a split caving shield. Attention is focused on other-than-normal loading on the canopy and its effect on deformation of the lemniscate links. Examples of the magnitudes of typical bending and twisting deformations are given. Schematics of the canopy, caving shield, and lemniscates showing important forces and moments are presented. Approximate minimum values of the forces and moments required to produce the deformations are calculated based on the mechanical properties of the material. The need for use of more inclusive three-dimensional design techniques is demonstrated.

Jan 1, 1991

By C. E. Jordan, B. J. Scheiner

The Bureau of Mines conducted research on the flotation hydrodynamics of fine particle flotation to improve the flotation efficiency in our domestic minerals industry. The turbulent fluid velocity profile was measured in various flotation cells at different levels of dissipation energy. The importance of dissipation energy and bubble size within the flotation cells for the flotation response of a chalcopyrite ore was evaluated. Both increased turbulent fluid flow and fine size bubbles improved the flotation rate of fine size chalcopyrite particles.

Jan 1, 1989

By R. Tanaskovic

The objective of study of climatic conditions in underground mines is to create a working environment suitable for normal development of operations. Disregarding the fact that the development of equipment and technology, especially during the past decade, made the work in underground mines much easier, it is observed, according to the number of professional publications, that increasing attention is devoted to the study of climatic operating conditions in mines of many countries. This indicates that the climatic operating conditions are closely connected with productivity, and in turn with mine production profitability, in addition to the protection of manpower health and working capabilities. Usually, the concept of unfavourable climatic conditions of operation implies increased mine air temperature and humidity and low air flow rate, resulting in impeded heat exhange between human organism and working environment. As known, above phenomena are present in deep underground mines where the heat problem exceeds the-problems related to other features of natural conditions of mining. On the contrary, unsuitability of climatic operating conditions in mines with shallower mining depths is manifested by inadequate heat, particularly during the cold winter period. The two stated aspects of unsuitable climatic operating conditions are not solvable only by mine ventilation, so the former case requires cooling and the later one heating of the air used to ventilate the pit, or part there of where the phenomena are manifested. Study of climatic operating conditions in mines is, due to the number of factors involved, a complex and time consuming task, and this was, among others, one of the reasons for inadequate study of these problems in many mines. However, it is evident that further development of mine production imposes the need to make the climatic operating conditions in mines similar to those existing in other activities, where increasing attention is being devoted to the improvement of these conditions. Development of mining industry in Yugoslavia, particularly over the past decades, caused several of our mines to approach mining depths where the heat regime has a major influence on climatic operating conditions. This imposed the need to determine and investigate heat regime parameters, especially those that cause unsuitable operating conditions. The results of such investigations in the case of the deep part of Lead and Zinc Mine "Trepca" - Stari Trg are briefly reported in this paper.

Jan 1, 1980

By Leszek W. Lunarzewski, Adam L. Lunarzewski, Raymond C. Pilcher

The Floorgas and Roofgas simulation programs are used to identify strata relaxation zones and their boundaries, to assess active gas sources from coal seams and gas¬bearing rocks and to determine relevant gassiness prediction coefficients for any local longwall. The paper shows that by use of the print-outs from the Floorgas and Roofgas programs the following benefits are achievable: • identification of the shear and gas discharge zone positions in the floor, strata relaxation angles and various gas discharge zone positions in the roof, which are both relevant to local geological and mining conditions • optimisation of cross-measure drainage hole length, location, number and angle of inclination calculation and definition of gas make prediction coefficients such as the release ratio from adjacent coal seams, specific gas emission during longwall extraction and the relationships between gas make, longwall width and coal production levels.

Jan 1, 1995

By R. P. King, S. Middlemiss

A method is developed to convert a measured distribution of fracture energies to the equivalent work index. The method assumes that the energy required to grind the material from the feed size distribution to the product size distribution is equivalent to the sum of the impact energies that are required to reduce the feed material by successive single impacts to the required product size. The method was tested by measuring the fracture energy distributions for quartz and comparing the resulting calculated value of the work index with the work index for this material measured using the conventional Bond laboratory procedure.

Jan 1, 1998

By Jaroslaw Drelich

This report briefly reviews the measurements and interpretation of adhesion forces measured between microscopic probes and substrates having micro- and nanoscaled roughness characteristics that were recently conducted at Michigan Tech using atomic force microscopy. The laboratory study concentrated on both rigid and deformable materials, with the probes larger than the size of roughness features of interacting surfaces. For such systems, a detailed surface characterization in terms of roughness parameters, asperity size and shape, and spacing between asperities, as well as analysis of deformation of materials is required. Analysis of the experimental data can be done with theoretical models, which are suitable for rough surfaces and therefore allows to normalize the measured forces. Alternatively, loading of the probe during adhesion force measurements can be managed properly to control deformations of the nano-scaled surface irregularities. Controlling the deformation reduces and even eliminates the effects of nano-roughness on the probesubstrate contact area, promoting conditions described by the contact mechanics models for the sphere-smooth substrate system.

Jan 1, 2005

By Chinmoy Sarkar

Mining organizations have been trying to employ best practices at exploration, exploitation and processing level to increase productivity in the supply chain. Traditional techniques of cost control can no longer meet the ambitious target of mine managers. An integrated perspective of Mining Value Chain with enterprise-wide application of information technology (IT) ensures the ability of every mining processes to improve energy, land, capital and labour resource performance while continuing to cut costs and achieve profitability. IT offers enormous potential in mining industry at shaping entirely new opportunities to create value. This paper characterizes important entities of Mining Value Chain and attempts to provide a vision on how IT can transform the mindsets of industry managers addressing the needs of the customers.

Jan 1, 2002