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By S. Zaharia

The authors present the state-of-the-art regarding natural and anthropic hazards on the stability of the saliferous Costiui basin. The factors that may potentially result in sliding, piping and collapse, are emphasized, given the existence of a large number of old salt mines. Also, a geotechnical risk map of this hydrosalt complex in Romania is presented.

Jan 1, 2008

By N. Powell, C. F. Spollen, B. A. Wills

A discussion of the practicalities of carrying out a material balance using simple nodal sensitivity analysis is given. The calculation of the errors involved is reviewed and the concept of co-variance examined through computer simulation. The use of co-variances in such calculations is shown to be practically insignificant. The method proves to be rapid and relatively accurate provided the circuit topology is correct.

Jan 1, 1991

By T. P. Meloy

A methodology is presented for finding feasible or locally optimal designs in the class of homogeneous, countercurrent, processing networks performing two-component non-sharp separations. The advantage of the methodology developed here is that given a set of independent performance criteria (specifications such as network separation factor, beneficiation ratio or recovery), a feasible or locally optimal countercurrent network design meeting those criteria can be found in one step. In the methodology, graph-theory was used to explicitly obtain the exact network responses of specific countercurrent networks. These responses were used to formulate the linear recursion equations whose solution gives the expressions for the countercurrent network responses which are a function of the stage transfer functions for two-component, non-sharp separations. These expressions are also functions of the network variables n and c. These expressions, together with the set of independent design criteria, were solved simultaneously for n and c using the Levenberg-Marquardt algorithm for systems of constrained, non-linear equations. The network variables n and c embody the coded network design information which is used to find the feasible network design which satisfies the set of independent performance criteria.

Jan 1, 1994

By D. M. Smith, M. J. Meulendyke, P. J. Moroz

An extensive program of marked ball wear testing (MBWT), laboratory corrosion studies, and worn ball surface analyses has been used to gain insight about the role of corrosion in the overall wear process. In some environments, localized corrosion is observed; the actual wear mechanisms in such cases are pitting/spalling and abrasion. Factors affecting the occurrence of pitting include the abrasiveness of the ore, corrosivity of the slurry, corrosion resistance of the media, and galvanic coupling effects. Elimination of pitting substantially improves overall wear resistance. When pitting is not observed, the contributions of general corrosion are significantly less.

Jan 1, 1988

By Changjiang Li, Jun Yang, Qiang Fu, Xu Chang, Xing Wu, Yubing Gao

With the development of underground mining, the deformation of roadway floor has increasingly become a major constraint on the safe and efficient production of coal mines. To address the floor deformation that was caused by massive stress concentration in roadway, an innovative method based on deep-hole directional tensile blasting technology is put forward. By taking No.122108 working face in Caojiatan Coal Mine as engineering background and analyzing the mechanism of deformation, a numerical simulation and field test are carried out to verify the effect on deformation control of this technology. It is found that the deep-hole directional tensile blasting technology can actively control the fracture position of the roof in the gob area and cut off the stress transmission path, so as to relieve the stress in the roadway. And since different blasting parameters have different impacts on the stress relief effect, a numerical simulation is implemented and it is found that the stress relief effect is the best when blasting depth is set to be 32 m and the blasting angle be 60°. By applying the optimal blasting parameters to the field engineering test, it can be seen that the deep-hole directional tensile blasting technology could effectively reduce maximum stress value and stress field range of the both sides of the roadway, and make the stress field far away from the roadway, thus effectively controlling the deformation of the roadway floor. The deep-hole directional tensile blasting technology can effectively solve the problem of roadway floor deformation and can be safely applied to engineering sites.

Jun 13, 2023

The development of information concerning mesothelioma in South Africa started with the 1959 finding of Dr. J. Christopher Wagner of cases of mesothelioma in persons living in the vicinity or working in crocidolite mines in Cape Province. After more than 40 years, the data from South Africa now provide important insights into the differences in mesothelioma risk associated with different asbestos fiber-types. Three case series reports and one analytical report were reviewed in this session. In total, information on 504 proven cases was presented. There were 28% of cases arising from occupational exposure in mining, 35% from non-mining occupations, 23% from environmental exposures; 14% where no exposure was established and 9% where the exposure was unknown. Among the 129 cases for which occupational exposure and asbestos fiber-type were established, 115 cases were associated with occupational exposure to Cape crocidolite; 1 case associated with occupational exposure to Transvaal crocidolite and 9 cases with occupational exposure to amosite (grunerite asbestos) and 4 cases with occupational exposure to mixed fiber-types. There were no cases associated with chrysotile asbestos. There were 33 cases of environmental mesothelioma linked to Cape crocidolite exposure and 2 to exposure to amosite and crocidolite but none to Transvaal amosite alone or to chrysotile. The evidence shows that amosite is capable of causing mesothelioma but that the major risk in South Africa is associated with Cape crocidolite.

Jan 1, 2008

By Anders Sellgren, K. Hansson, A. Jedborn

In the mining industry, conversion of fine particles into a slurry is often part of the normal processing of the ore. Therefore. from a system's point of view, slurry transportation would be considered as a natural alternative, all the way from the working face to the final processing. In underground mines, there is sometimes a considerable inflow of ground water that has to be pumped out. When the mine dewatering installations are integrated with a hydraulic hoisting system, the cost of power needed to pump out the ground water can be excluded from the cost of hoisting, compared with other modes of transporting the solids to the surface. The chief advantage of hydraulic hoisting is that the hoisting capacity can be increased at comparatively low total cost without necessitating the sinking of new shafts. Alternative examples include deepening of the existing mechanical hoisting system, truck, or conveyor belts transport in ramps to the present level. These often become very expensive. The economic effectiveness of hydraulic hoisting and hydraulic design considerations have been discussed by Kostuik (1965) and Sellgren (1985, 1986) for both small shallow mines and large deep underground mines. Objective and scope The objective of this study was to demonstrate the feasibiliy of hydraulic hoisting in hypothetical examples of mine deepening. Underground grinding to a maximum particle size of about 700 um (about 25 mesh) is considered. The pumping of ground ore products with positive displacement plunger or membrane type of pumps at working pressures of up to 15 MPa (2200 psi) is a thoroughly tested technique (Venton, 1986). Hydraulic hoisting system A hydraulic hoisting system is described schematically in Fig. 1. The ore is mined, handled, and crushed conventionally. It is then ground wet underground. The slurry is then temporarily stored in an agitated tank and pumped to an agitated receiving tank on the surface. The ore is then further processed in the concentrator. The capacity of a pipeline is very high. For example, an annual production of 500 Kt (550,000 st) of ore can be handled in a 100-mm-diam (4-in.-diam) pipeline. Systems layout - economic effectiveness Schematic mine layouts are presented that represent situations where hydraulic hoisting often is the most economical alternative. A situation where the ore is trucked to the level of the existing hoisting system is shown in Fig. 2 (following page). With hydraulic hoisting, only a shaft for ventilation, pipe- line, and personnel are needed. In a first phase (Fig. 2). a hydraulic hoisting installation with crushing and grinding units, storage facilities, and pumps has been located at a level of about 400 to 600 m (1310 to 1970 ft) below the surface. With further development of the mine, the hydraulic hoisting

Jan 1, 1990

By K. M. O’Connor

Time Domain Reflectometry (TDR) is a pulse testing technique developed by the telecommunications and power industry for use in locating breaks in cables. Variations of this principle have been utilized in applications pertinent to closure and reclamation of coal operations. This paper focuses on applications of TDR technology in the mining industry including monitoring of slope movement, abandoned mine subsidence, ground water levels and subsurface LNAPLs, landfill cover performance, and consolidation of mine tailings. TDR technology has been particularly effective for remote automated monitoring, and alarm systems have been implemented for monitoring subsidence.

Jan 1, 2003

By G. D. Elliot, R. L. Grayson, G. L. Winn

For the years 1990 and 1991, West Virginia's underground coal small-mine fatality rate was approximately 10 times higher than the national coal-industry fatality rate. Although the number of fatalities went down from 22 in 1991 to 17 in 1992, West Virginia still led the nation in coal-mining fatalities. A team of mining and safety professionals from West Virginia, interfacing with the Mine Safety and Health Administration and the West Virginia Office of Miners' Health, Safety and Training, studied this problem. A clear path for formal intervention was determined and is presented here.

Jan 1, 1996

By Larry J. Hughes

Ground-based electrical geophysical techniques have be valuable for three indirect exploration strategies: "tracer" sulfide mineralization, 2) mapping structure with or controlling mineralization, and 3) mapping proven to 1) mapping? associated alteration zones. When sulfide mineralization is associated with gold, it often can be mapped using induced polarization (IP). This technique can detect pyrite in amounts as small as 0.2% by volume, and in some cases can distinguish pyrite from anomalies due to graphite and clays. A case history illustrates mapping sulfides in a shear zone. Structure and alteration mapping are often the domain of controlled source audio-frequency magnetotellurics (CSAMT) due to the superior lateral resolution and depth penetration of this technique. Typical CSAMT targets include silicified sediments and volcanics, faults, brecciated zones, argillic alteration, clay and graphite horizons, and certain lithologies. Examples of mapping silicification and mapping epithermal alteration are presented in CSAMT case histories over Cannon mine in Washington and Hishikari mine in southern Japan. In our experience, four things are needed to use geophysics effectively in precious metals exploration. First, the explorationist must correctly identify the exploration stage at which the geophysics is most useful. Second, the explorationist must clearly define the types of "tracer" mineralization, host geology, or alteration which need to be defined by the geophysics. Third, the right electrical technique needs to be applied to the problem to provide the best chance of success. Fourth, the explorationist must be willing to commit adequate finances to do the geophysics properly. With careful adherence to these principles, geophysics can greatly enhance exploration success while reducing the total cost of exploration.

Jan 1, 1989

By M. M. Rajkovich, J. J. Zaluski, S. J. Gardner

The telephone rings at 3:20 a.m. and an exasperated voice on the other end says, “There’s been a mine explosion at Mine No. 5 and we have not heard from three units of men!” Twenty-three minutes later, the phone rings again and another panicked voice says, “There’s something wrong at the slurry impoundment, the pool level has just dropped five feet and we’re trying to figure out what’s wrong!” Thirty minutes later, the mobile phone rings and an excited security guard says, “We have reports of thick black water running down both the right fork and left fork of Straight Creek and both seem to be rising in the banks!” As if this isn’t enough excitement, the mobile phone rings again and a stressed company official says, “I just heard a report that black slurry is running out of the portals of XYZ Company No. 2 Mine, which is adjacent to our No. 5 Mine!” Is this all some kind of dream or nightmare? More importantly, however, if this could happen, what on earth do you do? Although we all like to think that “It can’t happen to me,” we all must admit that mine explosions do happen, slurry impoundments can rupture and creeks can flood with black water causing damage to others, including competitors. Your response must be quick, cool-headed, calculated and effective. This paper will examine the issues, concerns and ramifications of this hypothetical “disaster” and then present a systematic crisis management response. While each situation is different, there are general guidelines for forming an effective plan of action.

Jan 1, 2003

By A. Kevin Beaton, Robert W. Laakso

The desire for dry passageways promotes the NATM as it provides a final support system most suitable for the installation of a waterproofing membrane. Waterproofing during construction is a cost effective way to enhance safety and function as well as increasing the life of an underground structure. The NATM approach utilizes the surrounding mass as an integral element of the "ringlike" support system. At the Pennsylvania Turnpike Commission Lehigh Tunnel No. 2 various rock classifications were determined to require support measures ranging from 2 to 12 inches of shotcrete along with spiling, wire mesh, deformed bar, lattice girders and rock bolts as needed. Field instrumentation and monitoring programmes are a key factor for the success of the NATM. When the support "shell" stabilizes smoothing shotcrete, waterproofing and a final liner can be placed.

Jan 1, 1991

By T. J. Joiner

A critical demand exists to develop new mineral resources, and the need for exploration techniques to supplement costly test drilling is becoming; more acute. In the past few years more industries have begun experimenting with geophysical methods to locate and define mineral deposits and delineate reserves. The new techniques have proven profitable in many instances. As a part of a broad long range program to study the mineral resources of Alabama, and in response to requests from land owners and mining companies, the Geological Survey of Alabama is investi¬gating the occurrence of bauxite and kaolin deposits in the Eufeula area. This project is supported by special funds appropriated for this purpose by the Alabama Legislature.

Jan 1, 1966

By Daniel W. H. Su

The ability to predict the effects of longwall mining on topography and surface structures is important for any coal company in making permit applications and anticipating potential mining problems. The sophisticated finite element model described and evaluated in this paper is based upon five years of underground and surface observations and evolutionary development of modeling techniques and attributes. The model provides a very powerful tool to address subsidence and other ground control questions. The model can be used to calculate post-mining stress and strain conditions at any horizon between the mine and the ground surface. This holds the promise of assisting in the prediction of mining-related hydrological effects.

Jan 1, 1986

By William J. Miles

From a historical perspective, bentonite is the common rock term for various uses and applications. Its name originates from water-based muds near Fort Benton used for lubrication of wagon wheels during the 19th century migration to western territories (which are presently part of the United States) when the pioneers ran out of axle grease. From a clay mineralogy perspective, bentonite is composed primarily of montmorillonite, an expandable magnesium aluminum silicate clay mineral. When magnesium occupies an octahedral structural site that usually contains an aluminum atom, a negative charge is created. In order to neutralize negative charges, cations are drawn to the interlayer surfaces between clay mineral sheet structures. Modem applications for bentonite depend on the sodium or calcium cation populations and other characteristics of the clay mineral. When sodium is the dominant cation, the material is called sodium bentonite, also known as swelling bentonite, western bentonite or Wyoming bentonite. When calcium or magnesium is the dominant cation, the material is called calcium bentonite, also known as non-swelling bentonite w southern bentonite.

Jan 1, 2012

By Yuting Xue

The classification of rock and coal will assist in automated coal rib rating and shearer horizon control, and is studied with machine learning techniques in this work. A database of rock and coal images is created by filtering photographs taken by researchers from the National Institute for Occupational Safety and Health (NIOSH). The classifier was trained with patches extracted from the coal and rock images, and an accuracy score of 0.9 was obtained. The trained classifier was then applied to classify rock from a new coal rib image with three rock layers of different thicknesses, and good agreement was achieved. The results demonstrate that it is promising to use machine learning techniques and rib images for rock and coal classification.

By J. C. Adams

Although explosives constitute only a small portion of a mine's total cost, the relative success of each blast has a tremendous effect on subsequent activities such as excavation, crushing, and equipment maintenance. Beginning in January of 1993, tests were carried out to determine whether productivity could be improved by replacing standard ammonium nitrate fuel oil mixtures (ANFO) with a high density, high performance blasting agent. The study was carried out at gold mines, coal mines, and cement quarries in Nevada, California, Colorado, and New Mexico. A wide variety of rock types and blasting conditions were encountered. Results showed that at most operations productivity was sufficiently improved to more than offset the increase in explosives cost. This resulted in a net reduction in mining cost. This paper presents a summary of these results.

Jan 1, 1996

By Kot F. Unrug

When reading different studies discussing trends in coal mining, it appears that a substantial expansion of output by the year 2000 is predicted, even in the most pessimistic forecasts. Depletion of shallow, easy-to-mine deposits is only a matter of time, and the future average mining depth will increase. The proportion of slope to shaft mines operated during the next decades will change in favor of the shaft mines. Since an increasing amount of shafts in new nine developments seems to be inevitable, it appears appropriate to focus more attention on shaft design criteria. Some valuable papers have recently been published (1) that emphasize geotechnical aspects of shaft design. In the discussion that follows some other aspects of design criteria will be evaluated.

Jan 1, 1984

By Paul F. Ziemkiewicz, John J. Renton, Thomas Rymer

Any viable model or deterministic formula used to make predictions must follow certain criteria. The standard models and procedures used to project acid load from mining activities operate from a number of assumptions, some of which, although logical, are scientifically oversimplified and, hence, invalid. Highly variable field parameters have lead to highly variable acid projections. Kinetic tests are in themselves misnomers in that no parameters associated with chemical reaction kinetics are ever determined. Sampling error coupled with assumptions made as to the distribution mode of pyritic materials in rock units can lead to highly inaccurate conclusions explaining why acid generation often occurs where none is predicted. The fact that probability theory and paradigms governing luck and chance have not been incorporated into the science of acid prediction undermines any credence placed on such projections. To date, with few exceptions, the acid prediction is logically closer to a game of chance than practical science.

Jan 1, 1991

By D. R. Babich, E. R. Bauer

Noise-Induced Hearing Loss (NIHL) continues to be a concern of the mining industry. A new noise standard (30 CFR, Part 62) is aimed at reducing NIHL in mining through engineering and administrative noise controls. However, the difficulty and expense of implementing engineering controls can make administrative controls an attractive alternative for reducing worker noise exposure. Over the last three years, the National Institute for Occupational Safety and Health (NIOSH) has conducted worker noise exposure surveys in underground and surface coal mines and coal preparation plants. The surveys revealed numerous possible administrative controls and an approach to implementation and analysis. The surveys have shown that worker dosimetry, time-motion studies, and equipment noise profiling are important aspects of effectively utilizing administrative controls. A description of the approach for selecting, implementing, and evaluating administrative controls, and a list of administrative controls, are reported.

Jan 1, 2004