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By T S. Cochrane

This paper is based on observations made during a recent visit by the writer to three of the dust research laboratories .in West Germany, each .of which is mainly concerned with studymg the composition and character of the respirable dust produced in mines or at industrial sites. The three institutes are discussed as regards their orgamzat10n and duties, their methods of dust sampling and analysis, and recent trends in research and development. An extensive bibliography completes the paper. Introduction A RECENT trip to Europe to attend international conferences m Austria and m Belgium gave the writer the opportunity to visit a number of research laboratories and mines in Western Europe. The visits to the dust research laboratories in West Germany are the basis of this report. In Germany, cooperative associations formed prior to and since the turn of the 20th Century to promote the safety and welfare of their workers have recognized the effects of airborne dust on the general health of the labour force.

Jan 1, 1964

By L. I. Gyrskia, Y. V. Andreev, T. N. Greiver, G. V. Petrov

Traditionally, chromite ores are regarded exclusively as a monomineral raw material for extraction of chromium. The results of the investigations indicate a wide range of PGM in the Ray-Iz chromites, amounting to 1-3 ppm PGM. The study of products of primary gravity concentration from heavily and lightly disseminated ores (Tsentralnoe deposit, Ray-Iz block), showed that the platinum-group minerals are concentrated in the tails and slimes of the processed products, containing 10-30 ppm total PGM. Preliminary data make it possible to conclude that an in-depth study of the platinum mineralogy of the Ray-Iz block chromite ores is necessary to develop a process that will produce both chromium and the PGM.

Jan 1, 2000

By P. Tong-jiang

We studied mineralogical characteristics of the vermiculite samples from seven mines in China. We found three types of interstratified structures in the investigated samples: 1:1 regular interstratified structure, segregated interstratified structure, and random interstratified structure. The vermiculite samples from six mines are mainly composed of phlogopite?vermiculite interstratified minerals, and the samples from the other mine are composed of chlorite?vermiculite interstratified mineral. The samples with phlogopite?vermiculite structure have high contents of K2O, TiO2 and Na2O. The samples with chlorite?vermiculite structure have the highest contents of MgO and Al2O3. The cation exchange capacity of the samples is 17.3?99.0 mmol/100g.The exchangeable cations of phlogopite?vermiculite samples from Weili Mine mainly include Na+ and Ca2+, while those of phlogopite?vermiculite samples from Tongguan Mine mainly include Mg2+ and Ca2+. The thermal expansion ratio of the samples is between 9 and 32. The exfoliated vermiculite products from Weili Mine have the best mechanical strength.

Feb 27, 2013

By Irving Hartmann

Falls of roof in coal mines and means of preventing them have been subjects of study for many years, and an extensive literature has resulted. Usually each individual paper has placed emphasis on one phase of the subject, such as fatalities, nature and extent of nonfatal injuries, methods of tembering (particularly in rooms or other wide places), safety along retreating rib lines, and methods of causing falls in abandoned areas. It is only in recent years that there has been persistent question as to why

Jan 1, 1941

By Irving Hartmann

Falls of roof in coal mines and means of preventing them have been subjects of study for many years, and ran extensive literature has resulted, Usually each individual paper has placed 'emphasis on one phase of the subject, such as fatalities, nature and extent of nonfatal injuries, methods of tembering (particularly in rooms or other wide places), safety along retreating rib lines, and methods of causing falls in abandoned areas. It is only in recent years that there has been persistent question as to why

Jan 1, 1941

By Thomas Curtin

The Bureau of Mines, in its researches aimed to prevent wastes and to increase efficiency in oil-well practice, has investigated the matter of casing troubles and fishing methods. The results of the investigation are set forth in this paper. After expensive development work, many wells being drilled for oil have been abandoned because of casing troubles. These troubles in many instances have been thought to be insurmountable, whereas they are sometimes susceptible of solution. In fields_ where casing difficulties are of daily occurrence, methods have been evolved for combating them. Were these methods more widely known and applied wherever the same conditions exist, the oil industry at large would be greatly benefited. This report attempts to classify these troubles and suggests solutions that will save the operator discouragement and expense. It is assumed throughout this paper that the reader is so familiar with the ordinary oil-well drilling and fishing methods that detailed explanation is unnecessary. The well-drilling terms that are used herein will be readily understood by those for whom this discussion is intended. However, in order to avoid confusion as to the sense in which some of these terms are applied, definitions &re included.

Jan 1, 1920

By J. W. Reynolds

Introduction The Sullivan mine, at Kimberley, B.C., is the principal source of ore for the Consolidated Mining and Smelting Company of Canada, Limited. Current production amounts to about 2,500,000 tons of lead-zinc ore a year. With approximately 1,600,000 feet of percussion drilling and 700,000 feet of diamond drilling being carried on each year, any improvements in drilling practice are important. Testing of new equipment and drill bits is a major function of the Testing Department at the mine. Tungsten carbide bits have been the subject of many tests since 1947 and have been used in operations since 1948. This paper details with the methods of testing and gives comparative data on performance and costs for tungsten carbide bits as compared to steel bits. Operational use of tungsten carbide bits started in April, 1948, and the extent of application has increased considerably since that time. The scale of employment is illustrated in Table I, which also shows other statistics on the use of carbide bits. Up to the present time eighteen types of carbide bits or tipped steel, as made by six different manufacturers, have been tested. In general, one supplier's bits have been used in operations, but some large-scale operational tests have been carried out with other types. The types tried are shown in Table II. To date they have been, the subject of 33 tests, covering the destruction of 804 bits over an observed footage of 42,586 feet.

Jan 1, 1951

By O. T. Barrett, R. F. Aberethy, H. N. Cooper, Thomas Fraer, William L. Crentz

"INTRODUCTION The object of the techniques described in this report is to determine the possibilities of separating the components of a raw coal into such grades as may be necessary to recover some exceptionally clean functions for special purposes.To do this commercial gravity methods would require separation at very low specific gravities, entirely outside the range of conventional practice. Hence, a technique has been developed for breaking down cool ample, into very close fractions within the gravity range of the (-lean coal matter as well as for separating it from the refuse and particles.Such data on the fundamental specific-gravity consist of the clean-coal matter will serve to appraise the difficulty of the problem and to chow be accomplished if and when effective methods of making such separations commercially are developed."

May 1, 1945

By G. Zain, Abdel-Zaher M. A. Abouzeid, Y. S. Mustafa, A. A. S. Seifelnassr

The main forces acting on minerals in conventional size reduction units are compression, impact, attrition, and/or abrasion. Usually a combination of these forces shares the breakage action of the minerals with one or more of these forces dominating the breaking action, depending on the machine used. The present work concentrates on the behavior of quartz when stressed with compression force in a confined piston die. Several size fractions within the size range minus 10 mm to plus 0.85 mm were compressed in the piston die. The measured parameters are compression load, bed thickness, displacement as a result of compression, rate of displacement, and the size distribution of the products. It was found that the size distributions are, to some extent, different from those produced by the ball mill or the high-pressure roll mill. This is mainly because of the differences in the type of the acting forces in each case. It was also found that the cumulative weight of the distributions is reasonably normalizable with respect to the median particle size of the product. The specific energy expended is inversely proportional to the median size of the products, and the reduction ratios, xf/xp, are directly proportional to the applied compression force, and hence, to the specific energy expended. A simple model is suggested for predicting the particle size distribution as a function of the expended energy. The calculated values of the size distributions match fairly well with the experimental values, except at the very low energy levels, where most of the energy expended is consumed in the rearrangement and packing of the particles in the confined space with little or no breakage.

By S M. Stewart

Building and Maintaining Community Relationships   In mining terms, the town of Waihi is distinctive with the Martha mine situated right in the heart of the town. MarthaÆs central location and other mining activity nearby means there is an increased community focus on the happenings at the mine and the effects and impacts of mining. While WaihiÆs proximity to the mine is unique, all mines have a community context that they operate within.   Issues of proximity simply heighten awareness and emphasise the need for building and maintaining good community relationships. In the three years we have been working alongside the Waihi community, we have worked together with concerned and supportive residents, representatives of Newmont Waihi Gold and representatives of Hauraki District Council, to develop a collaborative framework for addressing the economic, social, environmental, cultural and spiritual wellbeing of the people of Waihi. This could not have occurred without the genuine commitment of all participants.   This collaborative focus has resulted in some tangible progress in Waihi which, in part, stems from people taking an interest in the town because the town is taking an interest in itself. As we have worked and learned within the process of building and maintaining a collaborative and sustainable community environment, we have tried to adhere to a philosophy and a set of basic principles. We believe that this approach, combined with a teachable skill set, helped to create the opportunity to develop a truly collaborative community environment which continues to grow. Our paper will describe this philosophy, these principles and the skill set that we have applied.   The application of the process in Waihi has resulted in a series of outcomes unique to Waihi. These outcomes include formation of the Waihi Community Vision committee, the Vision Waihi Trust and the subgroups set up to further the interests of particular groups, for the collective benefit of all the community.   Based on our experience of other situations, and on the way the Waihi process has developed, we believe that the identified principles and skills can be transported and used in other cultures and contexts. While the resultant outcomes may differ, the underlying principles will still apply. Progress will come from creating a sustainable environment within which the community (including residents, industry and regulatory authority) can determine its own internal relationships and the vibrant growing sense it has of itself.

Jan 1, 2006

By Robert W. Waytulonis

The mining regulations of all 50 States were reviewed by the Bureau of Mines, and those parts pertaining to the use of internal combustion (IC) engines (particularly diesel engines) in underground mines or confined spaces were extracted. Also extracted were subjects associated with the use of IC engines; for example, storage and handling of flammable liquids, maintenance, and ventilation requirements. As the laws now stand, 29 States have specific regulations that affect the operation of diesel engines in underground coal and/or metal and nonmetal mines. The other States have no regulations because either they have no mining activities or they defer to Federal regulations. Six states have regulations expressly prohibiting the use of diesels in underground coal mines. Specific contacts (addresses and phone numbers) precede each State's regulations to facilitate inquiries about regulation revisions and interpretation.

Jan 1, 1981

By Allen S. Smith

Analysis of the helium content of a natural gas presents more than the usual difficulties encountered in applying the thermal--conductivity method because of the relatively small amounts of this inert gas present and the wide variation in the other constituents. However, the numerous advantages of this method and its adaptability to continuously recording and control instruments make it worthy of consideration. A specific application of the method described yields quantitative results only when used with gas mixtures of known qualitative compositions which vary within predetermined limits. Periodic analyses for the helium content of a producing gas well may be conveniently made by an absorption method3/ and a continuous analytical method is not necessary for this purpose. Natural gas containing 1.75 to 1.90 percent of helium produced from Government-owned wells is processed in the Amarillo (Texas) Helium Plant of the Bureau of Mines. The helium extracted in the plant is supplied to the Army and Navy, and the processed natural gas is sold to a commercial gas company4/. As complete recovery of the helium in the raw material is not economically practicable, the processed gas contains 0.1 to 0.3 percent of helium, depending upon conditions of operation;- Production is checked against the helium removed from the gas, which before the installation of the thermal--conductivity apparatus was calculated from the analysis of a cumulative sample of the processed gas. As conditions of operation affect the residual helium content to a large extent, a composite sample was an uncertain index of the efficiency of the process.

Jan 1, 1934

By J. Lipp

The lion share of lithium produced globally originates from South American salars. The standard operation for lithium production utilizes an array of evaporation ponds. This process consume vast areas and is either very slow when relying on solar evaporation - roughly 18 months of residence time; or with very high energy consumption since over 90% of initial water volume needs to be evaporated. A new technology, based on solvent extraction was developed. Results indicate a distribution coefficient up to 30, and selectivity greater than 1,000 towards Na extraction. The loaded solvent is stripped using a strong mineral acid, and the product solution is the lithium derivative of that stripping acid. Utilization of this new LiSXTM technology results in reducing the area needed for a commercial plant as well as reduces the residence time. In addition applying different stripping acids can diversify the product line of such facility.

Jan 1, 2014

By B. Cavender

Mining managers trying to rapidly reduce production costs tend to implement a traditional set of top-down managerial practices: layoffs of employees, renegotiation of supplier contracts, cancellation of employee training, restrictions on travel, reductions in office supplies, and so forth. While these practices do reduce costs, the benefit is often limited in both magnitude and duration, and the workforce is usually left demoralized. Successful cost-cutters take a different approach. They make the continuous reduction of costs a priority for all members of the organization, whether managers or workers. The culture of these firms emphasizes the commitment, voluntarily given, of individuals and work groups to this goal. Cost cutting practices often reject all of the traditional methods mentioned above, but are far more numerous, innovative, and successful. This culture of cost reduction is the result of a set of leadership competencies that establish direction for the organization, align the organization’s various constituencies with this direction, and motivate and inspire the organization. Dramatic cost reduction then becomes a routine task rather than a heroic achievement.

Jan 1, 2000

By J. A. Morgan

IN the art of roasting sulfides it is well known that the lower the temperature and the higher the pressure of SO, the larger will be the amount of sulfate present in the product. However, the mechanism of sulfate formation is not generally understood. The following experiment" demonstrates in a direct way that, in the roasting of Cu2S, the sulfate forms from the reaction of Cu2O, formed by the oxidation of Cu2s, with gaseous SO, (or SO3) and 0,. Thus, the sulfate does not form at the sulfide surface. The reaction at the sulfide surface is the same whether or not sulfate is formed. Using an indirect method, Ong, Fassell, and Wadsworth' infer that sulfate forms after oxidation, during the roasting of sphalerite, agreeing with the observations of this paper. The method presented here of demonstrating that sulfate forms after formation of Cu2O is to roast a sample of Cu2S and then to locate and identify the phases formed.' A solid cube of cuprous sulfide, made by melting Fisher reagent grade Cu2S powder and measuring about 1.5 cm on edge, was placed on a Nichrome wire grid suspended over the top of an Alundum combustion boat. The assembly was placed in a tube furnace at 600°C and oxygen gas, flowing at 0.60 liters per min, was passed around the specimen for 24 hr. The furnace tube diameter was 1.5 in. The partially roasted sample was removed from the furnace and impregnated with resin No. BR 0014, obtained from the Palmer Products Co., and the impregnated sample was then mounted in Lucite. A cross section was obtained by grinding and the surface was prepared by the following steps: 1) grinding—60 grit, 3M disk, dry; 2) preliminary polishing —60 through 600 grit, 3M disk, dry; 3) polishing— 8 µ diamond putty, silk cloth; and 4) final polishing —1evigated magnesia in isopropyl alcohol, Selvyt cloth. The color micrograph of the polished surface is shown in Fig. 1. The layers present in the micrograph are given along the side. The comwositions of the various layers were established by Debye-Scherrer patterns. From this evidence the following sequence of reactions which occur in the roasting of Cu2S is inferred: 1) The oxidation of Cu2S occurs with oxygen which has been transported through the oxide-sulfate layer by either gaseous or solid state diffu- sion. The products of this reaction at the Cu2S surface are Cu2O and SO,. 2) The SO, diffuses out through the pores in the Cu2O and finally reaches a position in the Cu2O where the oxygen pressure and the SO, pressure have values such that the thermodynamic conditions for the formation of CuSO4 are fulfilled. Then, the mixture of SO2, SO3, and oxygen reacts with the Cu2O to form CuSO1. 3) The CuSO, decomposes by the evolution of SO,, or SO, and O2, to form the basic sulfate. This is reasonable, since the SO, gradient will decrease toward the oxygen gas phase from the CuSO4 layer. 4) For this same reason the basic sulfate will decompose to form CuO. The above sequence of events is based on the assumption that diffusion through the oxide and sulfate layers, rather than the reaction at the sulfide-oxide interface, is rate-determining. This assumption is supported by the observation that these oxide and sulfate layers combined are almost nonperme-able to the flow of gases through them. Acknowledgments This research was supported by the U. S. Air Force, through the Office of Scientific Research of the Air Research and Development Command. The authors wish to acknowledge the helpful suggestions of Ralph Wells of the Applied Research and Developmeit Laboratory, U. S. Steel Corp. References E. A. Peretti: A New Method for Studying the Mechanism of Roasting Reactions. Discussions Faraday Soc. (1948) 4, p. 174. - J. N. Ong, Jr., M. E. Wadsworth, and W. M. Fassell. Jr.: Kinetic Study of the Oxidation of Sphalerite. Trans. AIME (1956) '206, pp. 257-263; Journal OF Metals (February 1956).

Jan 1, 1957

The introduction of computer technology to the mining industry has produced many benefits for the mining engineer. The most significant is the dramatic increase in productivity realized by the individual user. This is important during times of competitive market conditions. Software for the minerals and energy industries has evolved substantially over the past decade. But even today it remains difficult to find a system that features the flexibility and integration capabilities to effectively (and cost-effectively) handle the needs of professionals in each phase of the mining industry - from exploration to reclamation. Several national software developers are now addressing this challenge. One Denver-based company, MINEsoft Ltd., offers a software package that is currently being used in each phase of the mining industry. The basic technology used in MINEsoft's database management system was developed in the 1960s. But during these early years of the computer industry, most of the technology was available only on mainframe computers, and then only as separate entities. MINEsoft's system unifies these various systems in one package that can be used on most computers manufactured today. Database Management System TECHBASE is a flexible, integrated database management system designed specifically for technical applications. The system features a database manager with no practical limit to the amount of data it can store, retrieve, and manipulate, according to the company. TECHBASE in¬cludes Applications Packages (TAPs) designed to meet the needs of professionals in a host of industries. Clients use the TECH BASE system to prepare many reports, including important EPA information. The package reduces data to a manageable level and enables users to increase productivity with a smaller staff. Mining engineers no longer need to do things by hand. What used to be a day's work can be accomplished in an hour or two. Exploration "Using the TECHBASE system to generate maps has probably saved us the expense of three or four draftsmen," says Ralph Fitch, regional manager and senior staff geologist with Chevron Resources in Portland, ME. "The system has great flexibility. You can treat it much like a spreadsheet. If you are halfway through with a particular project, the system allows you to add fields and calculations with ease but without starting over." Fitch uses TECHBASE for the "straightforward" plotting of results and generation of geochemical and geophysical profiles. "In exploration," he says, "these are the two key elements ... the generation of maps and data profiles. The system allows you to plot as many elements and variables in these areas that you like." Other aspects are important, too, says Fitch, including drill hole sections. "We use all the basic capabilities the system provides in the complete package," he explains. "When shopping for a system, TECHBASE was clearly dedicated to exploration in the

Jan 9, 1987

By M. Fan, Z. Long

"This paper presents some studies on recovering valuable elements from Chinese coal by-products, including coal combustion fly ash, stone coal ash, and coal flotation tailings. Both commercialized technologies and economic potential recovery methods are described in this study. Magnetically stabilized air-dense medium fluidized bed separation, tribo-electrostatic separation, froth flotation, and hydrometallurgical methods are discussed in recovering various valuable elements in Chinese coal by-products from different coalfields. These valuable elements include iron, carbon, aluminum, rare earth elements, lithium, gallium, germanium, uranium, titanium, scandium, silicon, vanadium and phosphorus, etc. The ultimate goal is to fully utilize all valuable elements in coal by-product. Each component within coal by-product should be efficiently segregated to its highest value. INTRODUCTION Coal is mainly composed of energy-producing elements carbon and hydrogen. In addition to these elements, coal usually contains many other valuable elements, including iron, aluminum, silicon, rare earth elements, lithium, gallium, germanium, vanadium, uranium, titanium, scandium, and phosphorus, etc. These coal-associated elements are significantly enriched in coal combustion by-product fly ash because of majority of main components, carbon and hydrogen elements, being removed. Table 1 provides the chemical composition range of the main elements oxides in 12 Chinese fly ash samples collected from coal power plants located in Northeast China, Northwest China, Southwest China, and Southeast China. It can be seen from Table 1 that the major mineral components of different ashes are similar, but the bulk chemistry of different fly ashes may vary widely due to the changes of ratios of the mineral components in different coals. The major mineral components in various Chinese coal combustion fly ash are silicates, iron oxides, and unburned carbon."

Jan 1, 2017

Study on Beneficiation Technology of a Refractory Fluorite Ore in North China

Sep 13, 2010

On the Art of Metallography (Howe Memorial Lecture), by F. F. Lucas; Beneficiation of Iron Ore. Abstract of paper by C. E. Williams followed by Round Table Discussion; A Statistical Analysis of Blast-furnace Data, by R. 8. McCaffery and R. G. Stephenson; Air Discharge of Circular Tuyeres, by R. S. McCaffery and D. E. Krause; Open-hearth Steel Process as a Problem in Chemical Kinetics. by E. R. Jette; Carbon-oxygen Equilibrium in Liquid Iron, by H. C. Vacher and E. H. Hamilton; A Thermodynamic Study of the Phasial Equilibria in the Bystem Iron-carbon (Abstract), by Yap, Chu-Phay; Influence of Dissolved Carbide on the Equilibria of the System Iron-carbon (Abstract), by Yap, Chu-Phay; Inclusions and Their Effect on Impact Strength of Steel, I and 11, by A. B. Kinzel and W. Crafts: Method for Electrolytic Extraction of MnO, MnS, FeS and Si02, Inclusions from Plain Carbon Steels, by G. R. Fitterer; Permanent Growth of Gray Cast Iron, by W. E. Remmers; Some Notes on Blue Brittleness, by L. R. van Wert; Austenite-pearlite Transformation and the Transition Constituents, by A. Sauveur; Age-hardening of Austenite, by F. R. Hensel; Transformational Characteristics of Iron-manganese Alloys, by H. Scott; Composition Limits of the Alpha-gamma Loop in the Iron-tungsten System, by W. P. Sykes; Magnetic Properties Versus AUotropic Transformations of Iron Alloys, by T. D. Yensen and N. A. Ziegler; Dilatometric Study of Chrome-nickel-iron Alloys, by V. N. Krivobok and M. Gensamer; Low-carbon Steel, by H. B. Pulsifer; Bright Annealing of Steels in Hydrogen, by F. C. KeUey; Development of Continuous Gas Carburieing, by R. J. Cowan. Transactions, Institute of Metals Division, 1931. 500 pages. Index. Papers and discussions presented before the Division at Chicago, Sept. 22-26, 1930 and New York, Feb. 16-19, 1931. X-ray MetallograpIhy: X-ray Determination of Alloy Equilibrium Diagrams (Annual Lecture), by A. F. Westgren; Suppressed Constitutional Changes in Alloys. by G. Sachs; Texture of Metals after Cold Deformation; by F. Wever. Theoretical Metallurgy: Studies upon the Widmanatitten Structure. I.—Introduction. The Aluminum-eilver System and the Copper-silicon System; by R. F. Mehl and C. S. Barrett; Studies upon the Widmanstatten Structure, 11.—The Beta Copper-einc Alloys and the Beta Copper-alumnum Alloys, by R. F. Mehl and 0. T. Mareke; Application of X-rays in the Manufacture of Telephone Apparatus, by M. Baeyerts; Thermal Conductivity of Copper Alloys. 11.—Copper-tin Alloys; 111.—Copper-phosphorus Alloys, by Cyril Stanley Smith; Thermodynamic Study of the Equilibria of the Systems Antimony-bismuth and Antimony-lead, by Yap, Chu-Phay. Ganeral: Cemented Tungsten Carbide; a Study of the Action of the Cementing Material, by L. L. Wyman and F. C. Kelley; Influence of Casting Practice on Physical Properties of Die Castings, by C. Pack; Fabrication of the Platinum Metals, by C. S. Sivil; Effect of Certain Alloying Elements on Structure and Hardness of Aluminum Bronze, by 9. F. Hermann and F. T. Sisco. The WorkinG oF Metals: Metal Working in Power Presses, by E. V. Crane; Forming Properties of Thin Sheets of Some Nonferrous Metals, by W. A. Straw, M. D. Helfrick and C. R. Fischrupp; Die Pressing of Braas and Copper Alloys, by J. R. Freeman. Jr.; Plasticity of Copper-sina Alloys at Elevated Temperatures. by A. Morris: Directional Properties in Cold-rolled and Annealed Copper, by A. Phillips and E. 9. Bunn; Effect of Combinations of Strain and Heat Treatment on Properties of Some Age-hardening Copper Alloys by W. C. Ellis and E. E. Schumacher; Constituents of Aluminum-iron-silicon Alloys, by W, L. Fink and K. R. Van Horn; Equilibrium Relations in Aluminum-antimony Alloys of High Purity, by E. H. Dix, Jr., F. KeUer and L. A. Willey; Equilibrium Relations in Aluminum-magnesium Silicide Alloys of High Purity, by E. H. Dix. Jr., F. Keller and R. W. Graham; Constitution of High-purity Aluminum-titanium Alloys, by W. L. Fink, K. R. Van Horn and P. M. Budge; Experiments on Retarding the Age-hardening of Duralumin, by E. H. Dix. Jr. and F. KeUer; Aluminum-silicon-magnesium Casting Alloys, by R. S. Archer and L. W. Kempf; Modulurr of Elasticity of Aluminum Alloys, by R. L. Templin and D. A. Paul; Quenching of Alclad Sheet in Oil, by H. C. Knerr.

Jan 1, 1931

By R. F. Kehrman

Voice Frequency (VF) electromagnetic trapped miner location devices were tested for reliability and effectiveness in 93 coal mines. Tests included uplink pulsed CW, downlink pulsed OW and downlink voice evaluations. Frequencies were 630, 1050, 1950 and 3030 Hertz. Overburden depths varied from 70 feet to 1550 feet. Successful communications were established at 91 of the 93 mines. Data indicate the transmitters and receivers will operate in practically all coal mine environments. Reliability and accuracy as location devices appear to depend on noise, depth and presence of metallic objects which distort the magnetic field. In addition, theoretical models appear to define best case situations in terms of noise and conductivity. Minor hardware problems were encountered, mostly involving battery contacts, switches and antenna cables on the receivers. No hardware problems occurred with the transmitters.

Jan 1, 1978