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By A. G. Fabbri

This paper aims at the application of quantitative criteria for evaluating the mineral potential of square cells representing areas in terrains being explored at a reconnaissance level. The assumption is made here that the evaluation methods used by an expert economic geologist can be organized into geological models for establishing associations within imaged areas, that correspond to pixels with similar characteristics. UTM-registered multiple data sets have been constructed which include seasonal LANDSAT 2 and 4 images, SEASAT scenes, selected airborne radar images, digitized aeromagnetic, gravity, bedrock geology and topographic elevation maps. The area of interest is located in the Bathurst Inlet, District of MacKenzie, N.W.T., where a preliminary mineral potential evaluation was performed by the Geological Survey of Canada to assess its suitability for a national park. The multiple data sets described in this paper can be used for many studies at different resolutions, for comparing processing methods in remote sensing and, most importantly, for evaluating the physical and spatial relationships between the different images in registered data sets.

Jan 1, 1989

By D. W. Park

Longwall mining is considered to be the most efficient underground coal-mining technique in terms of coal extraction ratio, production rate and safety standards. Due to the increasing demand for higher coal production, the recent trends have been to use wider panels and to maintain a faster face movement. For these reasons, longwall mining can result in unexpected roof falls, excessive face convergence, shield damage and numerous maintenance problems, which can cause sudden interruption of coal production as well as serious safety hazards. Recent work at the University of Alabama has been dedicated to the development of a longwall strata-control and maintenance system that can integrate real-time shield monitoring, data presentation, analysis, forecasting and warning modules. This integrated system has been called LoSCoMS. The main objective of the system is to provide minute-by-minute stability and maintenance information such as the following: high-load, low-setting pressure, leg leakage, etc.; the analysis of various mining and geological parameters to determine past and present roof characteristics; and the forecasting of loading patterns for the following mining cycles, the next periodic weighting, etc. By using this unique system, mine operations personnel are well aware of past, present and future roof-loading patterns at the longwall face and, thus, proper safety measures can be taken ahead of time.

Jan 1, 1999

By Klaus Böde

Within the national and international strategy of the German based construction company HOCHTIEF, the majority of its business units is equipped with the comprehensive software package ARISTOTELES. This software is a powerful business information system for all accounting and controlling related processes in medium-sized and large construction and other related companies. Due to the complexity of the software, time constraints, and limited financial resources an implementation of this software package requires thorough project management. In this paper the relevant elements of project management are outlined based on practical experiences gained during this international IT - implementation project. Special emphasis is directed to the identification and management of potential risks. In this case particular acknowledgement was given to the multinational nature of the project and modernization of the business. This includes thorough reorganization of the company, significant changes of job requirements, and substantial trainings for its employees. At the same time key success factors like knowledge transfer, adoption of Czech legal requirements, commitment of management, networked thinking, and integrated project planning come into play. The costs for implementation had to be carefully evaluated because the software was implemented in a country with a considerably low cost I price level. All these impacts to the business had to be managed within the scope of transformation of business and political environment from socialist to market driven economy.

Jan 1, 2002

By Richard Keith Corbin

Canadian junior mining companies whose gold exploration and exploitation programs take them across the border into the western United States should be prepared to deal with the myriad of title issues involved in acquiring unpatented gold mining claims. The purpose of this paper is to serve as an introductory outline for Canadian junior mining companies to mining laws of the United States, as well as to relevant laws of some of the western gold mining states. Topics will include the five w's (who, where, what, why and when) of Canadian junior mining companies1 rights and responsibilities in acquiring interests in U.S. gold mining properties by claim staking, lease or purchase. Historic terms of common parlance among U.S. miners, such as "claimjumping" are defined and discussed. Various legal doctrines, such as "pedis possessio" and "good faith" in the location of claims are covered as well. Controversial subjects of contemporary interest are addressed in some detail, such as whether to locate a bulk-mineable disseminated gold deposit with placer claims or lode claims, and whether lodes may be staked over placers. By thus heightening the awareness of Canadian junior mining companies, it is hoped that they can be properly prepared to avoid title disputes, and to win lawsuits when they are unavoidable.

Jan 1, 1988

By Balesh W. Konda, Andrew B. Cecala, George W. Klinowski

Methane ignitions continue to be a major concern to the longwall mining industry. In spite of numerous advances in technology over the past decade, there has not been a measurable reduction in the number of longwall face ignitions. These ignitions will continue to be a problem as deeper and gassier seams are mined, as production rates are increased through numerous improvements in longwall mining equipment, and as the output of the workforce increases due to improved management-labor relations. It is necessary to know methane liberations, emissions, and flow patterns in order to effectively deal with it and to design control technology to reduce the occurrence of longwall face ignitions. A cooperative research project between the Bureau of Mines and the Canada Centre for Mineral and Energy Technology (CANMET) has been established to address longwall methane problems. The initial direction of this work was to look at methane flow patterns during the entire longwall mining process, and more specifically to examine and compare methane levels and flow patterns for advance and retreat methods of longwall mining. Both advance and retreat longwall mining is practiced in the Sydney coal fields in Nova Scotia. In 1986, a study was performed on advancing longwall panels at the Lingan Colliery, and a similar study was recently completed at the Phalen Colliery on a retreating panel. Methane monitors were placed at various locations along the face, intake, return, and bleeder airways. Handheld methane monitors were also used upstream and downstream of the shearer mining machine. This setup allowed a determination of methane sources on the longwall panels, including: liberation from cutting with the shearer mining machine, emissions from the coal seam along the face, emissions from the gob area, and methane already in the intake air. The results from both studies are reported and the differences between the two longwall mining methods compared.

Jan 1, 1989

By Matthew E. Fowler, Jean Habimana, Roy F. Cook

The West Side CSO Tunnel, Pump Station & Pipeline Project is currently beginning construction along the downtown waterfront of Portland, Oregon. This4.3 meter diameter, 5,500 meter-long soft ground tunnel will be driven along the westbank of the Willamette River adjacent to buildings and utilities and several major pile-supported bridges. High groundwater pressure, extended lengths of gravel to cobble-size alluvium, and the need to control ground loss and surface settlements were key considerations in the selection of slurry tunnel boring machines for the project This paper presents an overview of the numerical modeling that was performed during design to estimate the strains and additional loads in the pile-supported structures and to assess the efficiency of proposed mitigation measures.

Jan 1, 2003

By Dominique Francois-Bongarcon

The rational and optimal determination of the design of a mining exploitation is a very intricate and difficult problem : the parameters are numerous, some technical, some economic or technico-economic which cannot be fully controlled; beside, deposits are estimated from very limited information and the choice criteria are not always quantitative, the economic context has to be anticipated by several years, and even the technological limits can change tomorrow. So, although very clever and performing numerical algorithms have been developed in recent years for open-pit design, we consider that this problem has not really been solved satisfactorily until now. The reasons are that people have concentrated their efforts on informatical algorithmical problems, and have assumed that the technical and economical data are well defined at the time of the study, which is generally not true. In particular, the mere fact of assigning dollar- values to blocks in order to maximize the total cash-flow is generally unrealistic because of the uncertainty of the data used. Consequently, the significance of the unique pit obtained as a result of these algorithms is questionable.

Jan 1, 1981

By D. C. McLean

One of the few innovations in hydrometallurgy in recent years has been the utilization of the chemistry of basic iron sulfates called jarosites. These have been used to make iron-zinc separations in the processing of zinc concentrates and are a very important factor in both the Duval and Cymet copper chloride processes as a means of preventing iron build-up in the closed leaching circuits. Copper oxychlorides are kindred compounds in that they are insoluble basic salts that form at low pH (1.5 to 3) and precipitate selectively from many base metal solutions. They have been reported in the chemical literature as far back as 1860, and a few of them are known in their mineralogical forms (particularly atacamite) usually as nuisance minerals because of their chloride content. Several patents describe their synthesis and use as fungicides and insecticides, and papers have discussed their formation as corrosion pro¬ducts on copper and brass piping (14).

Jan 1, 1979

By Saul J. Esdalera

The flotation response to amine collector and its adsorption on the mineral surface was studied as a function of pH and collector concentration. The flotation response increased in the order anorthite + intermediate plagih clases + albite, while adsorption of amine obeyed the Freundlich equation r = A.Cn. This adsorption is proposg to be due to a covalent bonding between the AlOH surface pups of the plagioclase altered outer layer and the amino group of the collector. Finally, the study showed thatmtial dissolution of the solid phase provides the necessary conditions for amine attachment on the mineral particles and consequent flotation.

Jan 1, 1980

By Miguel Carrera, Jose Arnal, Julian Ortiz, Maarten Haest, Fouad Faraj

ShovelSense is a complete solution for bulk ore sorting at the mine face that combines robust shovel bucket mounted X-ray fluorescence sensors, with real-time material classification, fleet management integration and supporting cloud-based data infrastructure, to ensure each truck always goes to the right destination. Correct truck destinations are a challenge in many current mining settings because the material classification of a truck, which is the key input into the truck destination, is often based on estimates at block resolution (~20x20x15m), with limited adjustment for blast movement and mixing. In this contribution, we present a geostatistical, data driven approach to estimate the potential value of bulk ore sorting at the mine-face for seven open pit mines. The approach is premised on the assumption that truck loads within blocks follow a simple gamma distribution. Standard ore control data from the seven mines have been used to estimate the potential bulk sorting value at these operations and ShovelSense-integrated dispatch datasets have been used to validate these estimates for specific benches on which ShovelSense operated. ShovelSense results validate the ore control data-based value predictions and show how at mine-face bulk ore sorting value varies between distinct deposit types. In general, deposit types that have higher bulk ore grade contrasts, display more potential ShovelSense value. The manuscript concludes with the limitations and opportunities of applying the proposed value estimation approach to evaluate at mine-face bulk ore sorting opportunities for open pit operations.

Jun 25, 2023

By Richard J. Waxweiler, Frank E. Lundin, Robert J. Roscoe, Victor E. Archer, Michael J. Thun, Joseph K. Wagoner

[Introduction] Since excess lung cancer mortality was first noted in the late 1800's among Joachimsthal-Schneeberg miners, there have been a number of studies of the long term health effects among various types of miners exposed to elevated levels of radon and its radioactive decay daughters. Substantial excesses of lung cancer have been noted among miners in the Joachimsthal mines (Sevc, 1976) , lead-zinc miners in Sweden (Axelson, 1979) , fluorspar miners in Canada (DeVilliers, 1971) , iron miners in Sweden (Renard, 1974) , uranium miners in Canada (Hewitt, 1976), and metal (Wagoner, 1963) and uranium miners in the United States (Lundin, 1971; Archer, 1976). The latter prospective cohort has also been shown to be at an excess risk of death due to tuberculosis, nonmalignant respiratory disease, and accidents when followed through September 30, 1974 (Archer, 1976). This report extends the followup of this cohort of miners through December 31, 1977 and expands the mortality analysis to investigate more cause-specific categories. [Methods] During the decade beginning with July, 1950, medical teams from the United States Public Health Service (USPHS) examined 3362 white and approximately 780 nonwhite males who had worked underground in uranium mines in the Colorado Plateau at least one month by January 1, 1964. Occupational, medical, and smoking histories were obtained during the examinations and often updated/confirmed during subsequent annual censuses of the miners conducted by the USPHS. The white miners now have been followed-up through December 31, 1977 using the Social Security Administration, Internal Revenue Service, direct telephoning and various other sources. Death certificates were obtained for the deceased and coded directly into the Seventh Revision of the International Classification of Diseases, Adapted, using the rules in effect at the time of death. Deceased miners for whom no certificate has yet been located were assumed dead on the date specified by the reporting agency, cause of death unknown. The uranium miners cohort was analyzed using a modified life-table system developed by the National Institute for Occupational Safety and Health (NIOSH). Person-years at risk of dying (PYAR) were calculated for each miner from his first USPHS medical examination date or date upon completion of one month of underground uranium mining if that was later. PYAR were calculated specific for five-year age groups, calendar periods, and periods after first underground uranium mining. The numbers of cause-specific observed deaths among the cohort occurring by December 31, 1977 were compared to the numbers of expected deaths. The expected deaths were calculated by multiplying the appropriate PYAR by the United States death rates for white males specific for five-year age groups, five-year calendar periods, and cause. The results were summed over the age and calendar period specific categories to obtain the total expected deaths for each cause. Standardized Mortality Ratios (SMR's) were calculated for each cause by dividing the observed number of deaths by the expected number of deaths and multiplying by 100. In some tables, two-sided 95% confidence intervals for the SMR's were computed using either Fisher exact confidence limits, if the observed frequency was less than eight, or approximate confidence limits, if the observed frequency was eight or greater, to indicate statistical significance. Because a priori hypotheses had been well established, one-sided lower confidence limits were used for tuberculosis, lung cancer, other nonmalignant respiratory disease (ONMRD), accidents, and total mortality. [Results] The cohort included 589 miners first examined in either 1950, 1951 or 1953; 753 first examined in 1954; 1235 first examined in 1957; 5 first examined in 1958; and 782 first examined in 1960. In Figure 1 the distribution of the cohort by first year of underground uranium mining indicates that 13.7% started before 1947 and would have thus had an opportunity to be followed beyond 30 years

Jan 1, 1981

By R. Bhaskar

The objective of the project was to optimize the ventilation parameters of a continuous miner underboom scrubber to further control. the amount of airborne dust discharged during mining, to further reduce the exposure of face personnel for an exhaust brattice ventilation system, and avoid recirculation of contaminants at the face. This research was performed in an underground coal mine in Utah. The tasks included preliminary face ventilation evaluation and optimization of the scrubber system to eliminate recirculation of the scrubber discharge air. Airflow tests were conducted on the currently used dust control system and the modified scrubber system. Tracer gas tests were performed to evaluate face ventilation effectiveness. Confirmatory tests of the scrubber system under actual operating conditions, modifications to the scrubber system, and a comparative evaluation of the scrubber system vs. the existing system were performed. This paper presents the results of the airflow pattern tests and the respirable dust levels in the modified scrubber system and the existing system. The optimized face ventilation parameters and the developed operating guidelines may provide the benefits of dust reduction, better face ventilation, and improved visibility.

Jan 1, 1994

By Ralph J. Anctil, James E. Palmer

According to relatively recent estimates by the US Geological Survey and the US Bureau of Mines, there are more than 0.9 Tt (one trillion tons) of remaining identified coal resources in the seven major western US coal-producing states and about 200 Gt (220 billion tons) in the demonstrated reserve base. Considering coal's current national production level of 0.7 Gt/a (0.8 billion tpy), these US reserve and resource figures are reassuring. Given here is a preliminary analysis of geologic constraints and an estimate of their effects on mining and recoverability of western coal. Mining Constraints USGS and USBM coal figures incorporate only thickness and depth, and are "blind" to many other major geologic constraints on mining and recoverability. The most important of these geologic constraints include: • coal seams too thin or too thick for conventional mining methods; • coal seams that cannot be mined due to insufficient separation from underlying or overlying previously-mined beds; • unstable or otherwise unfavorable roof strata; • soft or heaving floor strata; • coal seams that are too lenticular or discontinuous for conventional mining methods; • coal seams in intensely faulted areas; • coal seams having high angles of dip precluding the use of conventional coal mining methods; • coal seams that cannot be mined due to proximity of water-bearing strata; and • coal quality problems such as excessive ash, sulfur, chlorine, or sodium. Coal Thickness Present USGS-USBM classification for reserve base includes bituminous coal beds more than 0.7 m (28 in.) thick and subbituminous beds more than 5 m (60 in.) thick to depths of 305 m (1,000 ft). Both of these thicknesses are less than the thicknesses now considered mineable in the western US. The lower limit for bituminous steam coal in deep mines is about 1.5 m (5 ft). For subbituminous coal, a thickness of at least 2.4 m (8 ft) is generally required. Accordingly, the Bureau of Mines reserve base includes many thinner coal seams that will not be mined in the foreseeable future. Within the Powder River Basin of Wyoming and Montana many seams-Wall, Upper Pawnee, Lower Pawnee, Cache, Manning-range in thickness from 7.6 m (25 ft) to more than 30 m (100 ft) and occur at depths to 305 m (1,000 ft). These have been included in the Bureau of Mines reserve base. However, the mining technology required to mine these thick seams does not now exist. It will require many years for development. The ultimate recoverability from these thick seams is unknown, but could be as low as 25%.

Jan 8, 1982

By Adrian Smith

14.1 INTRODUCTION From the time the last recoverable gold is extracted from ore on a heap leach, the ore - now spent ore - changes from being the resource, indeed the raison d'etre of the operator, to a potential liability. The spent ore contains process chemicals and constituents leached from the ore both in the interstitial pore water in the heap and on the surfaces of spent ore. If these chemical species were released to the environment, it could have a potential impact on the quality of both surface water and groundwater resources. Accordingly, the spent ore must be left in a condition where it does not present a potential environmental liability. This can be accomplished either on a decommissioned pad or, if the heap leach is operated as a load/unload scheme, in a waste facility. In general, the residual cyanide level in the spent ore is the perceived controlling factor when determining whether the leached material is suitable for abandonment. Regulatory authorities set permit conditions for heap leach abandonment in terms of residual cyanide levels, for example, Smith and Struhsacker (1987). This chapter discusses cyanide degradation and methods for detoxifying a heap leach in order to meet regulatory limits/permit conditions for abandonment. Cyanide degradation and detoxification by "natural" processes are described initially, based on the chemistry and geochemistry discussed in Chapter 13. This leads to a review of chemical treatment processes for detoxification of spent ore. The advantages and apparent disadvantages are then appraised. 14.2 NATURAL DEGRADATION AND DETOXIFICATION For the purposes of discussion, "natural" detoxification processes can be divided into two alternatives: • Passive abandonment (the so-called "do nothing" option); and • Water In the first alternative, the spent ore is merely left on the leach pad to age; the second alternative involves the flushing of the spent ore with water.

Jan 1, 1988

By I. Michalakis

A geological and geophysical study was con-ducted at the area of Stylos, Hania in order to study the possible mechanisms of saltwater contamination. A new detailed geologic map in scale 1:5,000 was combined with the results of a time lapse geophysical survey using seismic and electrical methods. A fault system in the N-NE direction possibly favors the saltwater intrusion.

Jan 1, 2006

By Edwin A. Harre, John J. Mortvedt

Plants obtain nutrients from both air and soil. They absorb carbon dioxide mainly from the air, although some carbon dioxide may be dissolved in soil water which is absorbed by plant roots. Carbon dioxide, a gaseous form of carbon and oxygen, supplies the carbon which usually makes up 50% or more of plant structure. Growing plants use water more than any other biological substance. Plant nutrients dissolve in soil water and enter the plant via root absorption. Water is then given off into the air as the plant breathes or transpires. Water also supplies hydrogen and oxygen to plants. Plant roots absorb nutrient cations or anions by contact exchange with soil clay particles. Inorganic or mineral nutrients essential to plants are supplied through the soil. Inorganic or mineral composition of plants usually is less than 5% of their weight. In most crop-growing areas, much of this nutrition is inadequately supplied from soil reserves and must be provided by fertilizers. The role of the fertilizer industry is to provide economical, efficient, good quality fertilizers to improve or maintain soil productivity for optimum crop production. The essential plant nutrients other than carbon, hydrogen, and oxygen which often must be added to soils or plants are categorized as primary nutrients (nitrogen, phosphorus, and potassium), secondary nutrients (calcium, magnesium, and sulfur), and micronutrients (boron, chlorine, copper iron, manganese, molybdenum, and zinc). These classifications are based on quantity of nutrients utilized by plants and do not imply their function or degree of necessity. One point of major significance to the fertilizer industry is that not all fertilizer minerals contain the plant nutrients in a chemical form available to the plant. A product which may be considered a fertilizer mineral may require substantial processing or treatment before it becomes useful as a nutrient source or fertilizer.

Jan 1, 1994

By Edwin H. Bentzen, Immo H. Redeker

Important industrial minerals are separated and concentrated by froth flotation by industry today. The following descriptions are presented as an overview of the methods employed to separate and recover a few of these industrial minerals. The minerals described in this section of the book are not, by any means, the only important minerals treated by froth flotation. Other minerals, such as calcite, kaolin, wollastonite, rare earths and vermiculite were not included, primarily due to the confidential nature of the information held by the Minerals Research Laboratory and the Colorado School of Mines Research Institute. Flotation of nonmetallic minerals is sometimes viewed as alchemy. However, the art is, in reality, based on sound chemistry, experience and a little luck in the treatment of new ores. In the flotation of nonmetallic minerals, as opposed to base metal sulfides, highly specific treatment conditions are required to accomplish separations. The presentation of the treatment of each of the minerals described was outlined as follows: DEPOSITS PROCESSING SPECIFICATIONS FLOWSHEETS (in some cases) A presentation of the factors, often critical, which must be carefully investigated to accomplish successful flotation of nonmetallic minerals is presented in the section on Sulfonate Collectors, elsewhere in this volume.

Jan 1, 1986

By Gustavo A. Aristizábal-H, Oscar J. Restrepo-B, J. Alejandro Delgado-J

"In Antioquia region of Colombia – South America most of extractive activity is developed as artisanal and small-scale level, exploiting different types of minerals resources but predominantly gold. This is not only an ancestral livelihood of hundreds of families in this region, but also their unique way of subsistence. However, that situation has not had a positive effect in the sustainable development of this territory because of several unsustainability factors mainly related to mercury use for gold extraction, the incorrect management of tailings and the informal way in which miners perform their activity. In 2010 Antioquia was the place with the highest contamination by mercury in the world with serious effects in ecosystems and health of habitants of this region (Veiga 2010) This paper presents a Socio-Technical Model focused on strengthening capabilities and social capital of artisanal and small-scale miners and its surrounding communities in Antioquia region. This is based on processes of evaluation, design and implementation of appropriate technologies to obtain “clean minerals” without using mercury and with a right management of tailings. In gold extraction it is about gravitational methods of concentration, which take advantage of high density of this element. These methods not only are cleaner but more profitable for miners. Notwithstanding its technical origins, the current model proposes a holistic framework that manages the elimination of mercury in mining not only as a technology transfer matter. Thus, more than formalization the strengthening process seeks to promote a business vision in miners and to develop productive chains in surrounding communities, this means to improve the skills of artisanal and small-scale miners to organize in a corporative way and to help surrounding communities to provide support and supply services to mining and even to other companies. Besides, the articulation with local institutions drives to reinforce their functions of control and accompaniment. In shorthand, this effort aims to empower local institutions, miners and surrounding communities in such a way they are able to face together their own development challenges in a sustainable way."

Jan 1, 2017

By D. Maxton

INTRODUCTION This paper traces the application of High Pressure Grinding Rolls (HPGR) at industrial and pilot scale in Australia. The Argyle Diamond Mine installed the first of two smooth segmented HPGRs during 1990 in an open-circuit secondary-tertiary crushing application to increase throughput. In 2002 a third HPGR was added to improve liberation and so increase the recovery of smaller diamonds. The latest improvements in wear technology (tyre with tungsten carbide studs) were incorporated in the design of this machine. Extensive HPGR pilot-plant trials were undertaken during the 1990s at both the Kalgoorlie Consolidate Gold Mine and the Boddington Gold Mine. The purpose of these trials was to evaluate HPGR as a method to increase throughput, as an alternative to SAG milling, and also to ascertain if downstream benefits existed. One of the challenges for HPGR circuit designers is to translate what occurs at small laboratory and pilot scale into what is likely to happen in a full-scale circuit. Scale-up from pilot machine results is normally recommended by manufacturers. However, such tests need relatively large quantities of material, particularly if meaningful data on wear are to be obtained. Laboratory tests are preferable, as they need relatively small quantities of ore, but may be questioned in terms of how they relate to full-scale operation. Modelling and simulation have played a particularly important role in this respect in Australia. Models are available which have proven to be very accurate at being able to scale throughput and specific energy response from laboratory to industrial machines. More recently, work in Australia has also been done in developing a model which has the potential to scale laboratory wear data as well.

Jan 1, 2004

By K. E. Hjelmstad, W. H. Pomroy

In the event of fire underground, it is essential that all miners be warned as quickly as possible. With mine air rapidly depleted of oxygen and contaminated with smoke and toxic fire gases, any delay in the warning signal could have disastrous consequences. Unfortunately, present mine fire warning systems, such as stench, audible or visual alarms, telephones, and messengers, are often slow, unreliable, and limited in coverage. Recent research by the US Bureau of Mines has established the feasibility of ultralow frequency electromagnetic signaling for underground mine fire warning. Infield testing completed thus far at five mines, signals of from 630 Hz to 2000 Hz were transmitted through rock up to distances of 1645 m (5400 ft) to a pencil-sized ferrite-core receiving antenna and intrinsically safe receiver circuit. Theoretical analysis indicates a capability to transmit effectively for distances in excess of the maximum depths of most American mines, which is about 900 to 1000 m (2950 to 3280 ft) . The prototype system uses off-the-shelf components and state-of-the-art technology to ensure high reliability and low cost. This technology would enable simultaneous and instantaneous warning of all underground personnel, thereby in- creasing the likelihood of successfully evacuating a mine during a disaster. This report discusses the theoretical basis for through-the-rock ultralow frequency electromagnetic transmission, design of the prototype transmitter and receiver, and the results of in-mine tests of the prototype system.

Jan 1, 1991