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Provide a rapid, reliable means of warning underground miners of a fire or other emergency. Approach An ultalow-frequency electromagnetic signaling system was designed, breadboarded, and tested at various under around mines. How It Works Current fire warning systems for underground mines, such as stench, audible alarms, and messengers, arc slow, unreliable, and seldom achieve total mine coverage. An ultralow-frequency electromagnetic fire warning alarm system with true through-the-earth signaling capabilities was developed to solve these problems. The system was originally designed for high-back room-and-pillar mines where stench systems are unusable due to the low velocity of mine air flow. However, the system has an application to all underground mines.

Jan 1, 1988

Banks' focus in using cash flow methods can differ markedly from that of equity investors. This paper attempts to explain and describe bankers' approach by: ò outlining the fundamental difference between banks' and investors' risk / return profiles. ò describing lenders' consequent use of cash flow methods in mineral valuation. areas. explaining lenders' specific treatment of key risk Fundamental to understanding banks' appraisal of mineral projects is the appreciation that lenders have a basically different risk profile and outlook from those familiar to equity investors. Lenders do not normally participate in any project upside. The economics of lending dictate that banks can only accommodate a low probability of loan default and consequently banks' principal focus in mineral ""valuation"" is ensuring an acceptably comfortable probability of debt repayment. A simple conceptual explanation of lenders' risk / return position is outlined.

Jan 1, 1994

By Özgen C. Karacan

It is generally accepted that typical coalbed gases (methane and carbon dioxide) are sorbed (both adsorbed and absorbed) in the coal matrix causing it to swell and resulting in local stress and strain variations in a coalbed confined under overburden pressure. The swelling, interactions of gases within the coal matrix and the resultant changes in the permeability, sorption, gas flow mechanics in the reservoir, and stress state of the coal can impact a number of reservoir-related factors. These include effective production of coalbed methane, degasification of future mining areas by drilling horizontal and vertical degasification wells, injection of CO2 as an enhanced coalbed methane recovery technique, and concurrent CO2 sequestration. Such information can also provide an understanding of the mechanisms behind gas outbursts in underground coal mines. The spatiotemporal volumetric strains in a consolidated Pittsburgh seam coal sample were evaluated while both confining pressure and carbon dioxide (C02) pore pressure were increased to keep a constant positive effective stress on the sample. The changes intemal to the sample were evaluated by maps of density and atomic number determined by dual-energy X-ray computed tomography (X-ray CT). Early-time images, as soon as CO2 was introduced, were also used to calculate the macro porosity in the coal sample. Scanning electron microscopy (SEM) and photographic images of the polished section of the coal sample at X-ray CT image location were used to identify the microlitho types and microstructures. The CO2 sorption-associated swelling and volumetric strains in consolidated coal under constant effective stress are heterogeneous processes depending on the litho types present. In the time scale of the experiment, vitrite showed the highest degree of swelling due to dissolution of CO2, while the clay (kaolinite) and inertite region was compressed in response. The volumetric strains associated with swelling and compression were between ± 15% depending on the location. Although the effective stress on the sample was constant, it varied within the sample as a result of the intemal stresses created by gas sorption-related structural changes. SEM images and porosity calculations revealed that the kaolinite and inertite bearing layer was highly porous, which enabled the fastest CO2 uptake and the highest degree of compression. Keywords: Coal; Carbon dioxide; Sorption; Swelling; Sequestration; X-ray computed tomography; Volumetric strain; Gas outbursts

By Amy McBrayer, Vladislav Kecojevic, Juan David Valencia Quiceno, Dragan Bogunovic

The mining industry’s commitment to innovation reflects a history of adopting technological advancements to enhance workplace safety, environmental sustainability and vocational training. The objective of this research was to develop an augmented- reality (AR) system for heavy-equipment operators (HEOs) in surface mining. The developed system has the potential to enhance mine safety, training and data-driven decision- making, which presents a significant step toward a more sustainable, effective and technologically driven mining training, contributing to the industry’s evolution and growth. The AR training system leverages Microsoft’s Power Platform and HoloLens 2 capacities to provide operators with detailed and immersive training guides for three mining equipment, including bulldozers, motor graders and haul trucks. AR guides combine speech controls, 3D objects, informative images and explicative videos in the real working conditions to enhance the operator’s learning process. The system has the potential to modify the training structure based on user performance and provides an efficient approach to data collection during training. This project was developed and applied through a case study in a surface mine in the Southern United States.

Feb 1, 2025

By A. E. Bellis

THE CHAIRMAN (ALBERT SAUVEUR, Cambridge, Mass.).-Any information likely to throw light on the constitution and proper treatment of high-speed steel in order to obtain maximum results, should surely he welcomed. All users of high-speed steel, I believe, will agree with the authors that, in order to obtain satisfactory results, it is not sufficient to heat all brands of high-speed steel to one and the same temperature; apparently very slight differences of chemical composition seem to call for marked differences in temperature. I think that all of us agree that a properly treated piece of high-speed steel should have a fine austenitic or polyhedral structure and that an appreciable quantity of free carbide may be present in the case of very high tungsten steels. What we seem to lack is a satisfactory method, quick and reliable, of ascertaining when the proper structure has been obtained. I think Mr. Bellis' paper is a step in the right direction. To the untrained eye, however, it is not an easy matter to select from some of his photomicrographs the one representing the best structure; for instance, in the case of steel A, we wonder why temperatures of 2,250 and 2,300 do not yield the same results, seeing that both structures are apparently alike, and the same might apply to some of the other samples. I have no doubt, however, that the experienced observer is capable of detecting structural differences that are not made plain here and by which he is able to select the proper quenching temperature. COLIN G. FINK, East Orange, N. J.-On page 68 the authors say that the use of a barium chloride bath to eliminate this difficulty has the disadvantage that the surface of the tool becomes decarbonized." I would like to ask whether they actually found that the surface was decarbonized, or whether they base this conclusion on softening alone? A. E. BELLIS, Springfield, Mass.-No, we have never demonstrated that it was a decarbonization, it is just the softening of the steel. The addition of ferrocyanide to the ferrochloride bath has been suggested. I think that is not altogether satisfactory, because the ferrocyanide bath changes composition very rapidly at these high temperatures, and it would be just a question of luck whether or not it had too much or too little ferrocyanide in the bath giving equilibrium with the carbon content.

Jan 4, 1917

By C. D. Anderson

A variety of processing technologies exist for recovery from both primary and secondary sources of rhenium. Currently, there are no known primary rhenium deposits; thus, the method in which primary rhenium is produced is dependent on the commodity of which it is a byproduct, e.g., copper, molybdenum, uranium, etc. In addition, focus on the recovery of rhenium from secondary sources, such as alloy scraps and catalysts, is continually growing. This paper presents a review of both primary and secondary processing technologies for the recovery of rhenium.

By P. C. Schutte

The objective of ergonomics is to enhance the effectiveness and efficiency with which human tasks are carried out. Furthermore, the objective is to improve desirable human values. This can be achieved by enhancing safety, reducing fatigue and stress, increasing comfort, increasing job satisfaction, having greater user acceptance and thereby improving the quality of life. Mechanization has influenced the prevalence of injury, mainly due to the application of human physical effort as the power source. With mechanization, the operator?s function is now essentially one of control rather than being an energy source, however, the risk of injury has not diminished. Mechanization in itself has introduced inefficiencies, health risks and physiological stress. The major objectives of ergonomics are discussed through examples of acceptable and less successful implementation of ergonomics within mechanized mining. The influence of the machine system on the human is addressed and practical solutions to improve and optimize the interaction of the human and the machine are outlined. Furthermore, practical examples of control and display integration, anthropometric and biomechanic influences on design, orientation, posture and stereotypes are used to accentuate the advantages of the application of sound ergonomics principles to the specialized area of mechanized mining.

Jan 1, 2002

By G. A. Gamble

"The inlet air velocity profile of any surface mine ventilation fan is an important factor when designing the connecting ductwork from the mine shaft collar to the fan. Deficient fan performance can be the result of ductwork that adds unnecessary pressure loss and/or adversely influences the fan inlet air conditions (velocity profile). The need for optimized inlet air conditions begins with discussing the process of performance testing during the development of the fan performance curve. Additional discussions include design of the shaft collar connection and the connecting ductwork. A preferred design of ductwork for parallel fan installations will be illustrated.INTRODUCTIONThe inlet air velocity profile of any surface installed mine ventilation fan is one of the most important factors to consider when designing the connecting ductwork from the mine shaft collar to the fan. Oftentimes deficient fan performance can be traced to poorly designed ductwork that adds unnecessary pressure loss and/or adversely influences the fan inlet air conditions (velocity profile). Such designs may lead to added power requirement, excessive vibration and noise, and reduced fan performance.Understanding the need for optimized inlet air conditions begins with discussing the process utilized when factory testing takes place during the development of the fan performance curve.Additional discussions include design considerations for the shaft collar connection, the connecting ductwork, and fan inlet. Illustrations of cost savings and pressure losses will be included for audience consideration. The design of ductwork for parallel fan installations on the surface is another issue that requires consideration. A preferred method will be illustrated.The selection of accessory components, such as self-closing doors, can also add to the potential for reduced fan performance. Several components will be discussed.An elementary presentation of the Air Movement and Control Association (AMCA) Standard 201 “Fans and Systems” will be included to provide background for those audience members that want additional technical explanations of the need for a uniform inlet air velocity profile at the fan inlet."

Jan 1, 2019

By Dean E. Harris

The realignment of U.S. Highway 95 in Sandpoint, Idaho, is being designed on a site underlain by glaciolacustrine soil that includes very thick deposits of soft, sensitive clay to estimated depths of greater than 200 m. The highway realignment will include construction of numerous embankments, mechanically stabilized earth (MSE) retaining walls, and pile-supported bridges. The area of the proposed new highway corridor also includes existing historic and commercial buildings, a railroad, sensitive environmental areas, and economically vital tourism/recreational assets. The evaluation of pile axial capacity included the use of a variety of methods, including total stress, effective stress, and empirical methods using the results of piezocone soundings and conventional borehole and laboratory tests. These methods were used along with the findings from an instrumented static loading test to design the piled foundations for the bridges. A critical factor throughout the design of the pile foundations was controlling settlements to levels that could be tolerated by the bridges. Also, because of the proximity of the pile foundations to the existing structures and the proposed new embankments, the project has required careful consideration of the potential interaction between these elements. The analysis of piles also considered the potential for settlement of embankments, drag loads on the piles, and downdrag.

Jan 1, 2003

By Marcelo B. Mourão

The reduction of iron ores by solid carbon, when both are agglomerated together in the form of pellets, has important kinetic advantages. Although several studies have been performed on the subject, some points on the controlling mechanisms need clarification. There is a big scatter in the values of the apparent activation energy reported in the literature, and this may be due to factors like heat transfer, flow of gases in the reduction system, pellet size and composition. This work is concerned with the effect of several parameters on the reaction rate. The parameters studied were temperature (in the range 1173 K to 1423 K), carbon type (coke or charcoal), pellet size, gas flow rate, catalyst action of the produced metallic iron and added sodium carbonate. It has been shown that the values of the apparent activation energy can change according to the reduction conditions employed, and hence any modeling effort will have to take account of these parameters. EPD Congress 1994

Jan 1, 1994

By Pierre Rocque

The Red Lake Mine is located approximately 600 km northwest of Thunder Bay. This 545 tpd (600 tons/day) underground narrow vein gold operation is set to produce in excess of 14.8 tonnes (475,000 ounces) in 2001 at a cash operating cost below 75 U$/oz. The high-grade nature of this deposit (>55 g/t or >1.6 opt) coupled with its complex geological environment and relatively deep location dictated the choice of a very selective primary mining method, Mechanized Overhand Cut and Fill. In addition to geological challenges, mine design issues such as material handling, ground stability and requirements for yieldable ground support are also discussed in this paper.

Oct 1, 2001

By Lloyd R. Nelson

Selective carbothermic reduction is the preferred method of treatment of electric arc furnace (EAF) dust (listed hazardous waste, K061). The process maximizes the recovery of recyclable constituents by concurrent production of saleable zinc metal (directly condensed from the furnace off-gases), an innocuous, disposable iron oxide-rich slag, and some metallic iron. Results of a mineralogical investigation of a foaming slag produced during selective carbothermic reduction treatment of EAF dusts are presented. Wiistite and tricalcium silicate were identified by reflected light microscopy as the primary crystalline phases contained in a glassy matrix, but this technique failed to reveal any solid phases that could have significantly contributed to foam stability. It was concluded therefore, that the foam had been unstable, and had been primarily generated by copious gas evolution associated with the sudden reduction of the slag by an inadvertent addition of carbonaceous reductant. This is consistent with the susceptibility to foaming, when subjected to sudden excesses of carbon, of the slags produced by selective carbothermic reduction, because they still contain unreduced components such as iron oxide.

Jan 1, 1994

By S. P. Mishra, G. R. Chaudhury

The adsorption of Cu2+ ions by Penicillium sp. displayed a dual rate, with an initial faster phase followed by a slower one. The adsorption rate increased with increasing pH due to chemical and biochemical reactions. The Cu-loading capacity of the biomass increased at higher initial Cu2+ concentrations. Above 40 degrees C the adsorption rate decreased which may be due to partial hydrolysis of biopolymers which are essential constituents of the cell wall. Adsorption kinetics followed the Freundlich isotherm and the equilibrium concentration that was calculated on the basis of the isotherm matched the observed value well. A series of theoretical adsorption curves were produced using mathematical correlations between the mass transfer coefficient, the Cu2+ ion concentration at equilibrium and at time t. The correlation between the theoretical and observed adsorption rates for different experimental conditions was good. It was concluded that the results from the study were best explained using a mass-transfer adsorption model

Aug 1, 1995

By Dennis L. Paisley, Thomas P. Turner

Laser slapper detonators are the next generation detonator under development at the Detonations Systems Group at Los Alamos National Laboratory and function very similarly to an electrical slapper. A fiber optic transmits a laser pulse to ablate a thin metal film. This film, or flyer as it is commonly called, is launched through a short barrel to km/s speeds. The flyer shock loads or slaps a high density pressing of secondary explosive, setting off a detonation therein. Laser slapper detonators afford a number of safety advantages over other conventional detonators. Most important they require very high peak laser powers to operate, orders of magnitude larger than possible sources of natural or man-made accidental stimulus. Because light is transported over fiber optics, laser slappers avoid many of the electrical hazards associated with detonators. Use of insensitive, secondary explosives makes these detonators safer to handle, manufacture, transport, and deploy.

Jan 1, 1994

By H. Forster, F. H. Koenemann, U. Knittel

The greenstone belt developed along the Sandawana line, an anastomosing, transcrustal shear zone. The lode gold is concentrated in veins and along brittle-ductile shear zones and other faults. Gold contents of 200 rock samples were found to be well below economically significant levels, excluding purely syngenetic deposit formation. Average gold content of unmineralised banded iron formation decreases from 7.3 ppb in the east (Manica) to 1.6 ppb in the west (Odzi), where depletion reflects hydrothermal leaching. The mineralising fluids may have been generated during deep crustal deformation, metamorphism and magmatism. Gold was hydrothermally deposited during carbonatisation and sericitisation of ultramafic and mafic rocks and during hydrothermal overprinting of banded iron formation and felsic rocks. It is present in native form and as microscopic to submicroscopic inclusions in pyrite, arsenopyrite and pyrrhotite. Argentiferous galena and other sulphides are commonly observed. Rezende, which produced over 38 t Au, is hosted by a granodiorite stock. By-product gold was produced from Cu-Ni sulphides at Mundonguara. The deposits are related to the older, but not the younger, of the granitoids intruding the belt's supracrustal sequences; the estimated age of mineralisation is 2700-2600 Ma. Odzi district, with 61 mines, has produced only 3.5 t Au as its higher-level host rocks have apparently been eroded. Mutare (formerly Umtali) district, with 133 mines and 9 placers, has produced 68 t Au (65 t from Rezende and adjacent deposits), and Manica district, with 23 mines and 8 placers, 12 t Au. Estimated reserves for the Rezende area are 20 t Au and for Manica district 4 t lode Au and 19 t placer Au

Apr 1, 1996

By D. H. Thompson, A. W. Tracy

Season-cracking is a type of failure of brass that results from the simultaneous effect of stress and certain corrodants. The object of this paper is to present data that will aid in a more complete understanding of the mechanism of season-cracking and related phenomena. Results presented show that certain high copper alloys are susceptible to season-cracking or stress-corrosion cracking, and possible explanations are discussed. Starting at least as far back as 1906, many papers have been devoted to this subject but the symposium1 held in Philadelphia in 1944 is the richest source of information. In order to study season-cracking, several of the many variables were held constant so as to learn the effects of others. Season-cracking is generally understood to refer to the corrosion cracking of brass having internal stresses;²,³ it is a special case of the general stress-corrosion cracking. Inasmuch as applied stresses are more readily produced and controlled, they were used exclusively in this research and the resulting phenomenon must he called stress-corrosion cracking.²,³ Only constant tensile stresses were used. The agents believed to be most frequently responsible for season-cracking are ammonia. amines and compounds containing then]. Both moisture and oxygen also appear to he necessary. Therefore, an atmosphere containing ammonia, water-vapor and air was selected for these tests. Briefly, the work consisted of exposing sheet metal specimens, having a reduced section ¼ by 0.050 in., of copper-base alloys to the effect of static tensile stresses between 5,000 and 20,000 psi and simultaneous contact with a. continuously renewed atmosphere containing 80 pct air, 16 pct ammonia and 4 pct water vapor at 35°C. The gas mixture and the speci- mens were maintained above the dew-point. The time-to-failure in minutes was the primary measure of results. In order to limit the experiment to finite time, it was considered that a specimen which had neither failed nor undergone microscopically detectable cracking in 40,000 min. (4 weeks) while under a stress of 10,000 psi or more could be considered immune to cracking. This is merely a convenient limit and is not to be considered proof of immunity. Supplementary tests in the absence of stress using weight loss or microscopical appearance as measures of attack were made. Apparatus The apparatus used in this research is shown in Fig 1. To facilitate the description it may conveniently be divided into six parts: stress-producing units, test chamber, gas train, electrical controls, timers and gas analysis device. A stress-producing unit is shown in an exploded view at the left in Fig 2. At the right is an assembled unit with a specimen in place in the lower portion; it is this part that remains in the ammonia atmosphere during a test. The upper part contains a spring, a central threaded rod, a large nut and necessary washers, pins, and so forth. Stress is produced in the specimen by screwing down the top nut against the spring, thus putting a tensile load on the central rod and so on the specimen. The wrench that turns the nut by extending through the upper cap, is seen at the upper right of the figure. The magnitude of the load is gauged by measuring from the pin that extends through the side of the tube, to a fixed point on the large flange. Measurement is made with a vernier beam caliper, shown at the right of the figure. The necessary spring compression to give a desired stress is calculated from the calibration curve of the spring and the dimensions of the specimen. The test chamber, center Fig 1, consists of a thermally insulated steel box 32 in. long by 10 in. high by 7 in. wide. A horizontal baffle reaching nearly to each end divides the chamber equally. Below this baffle are inlets for air and ammonia, a heating coil and a fan. Thus the gases are warmed and mixed in the lower level and flow past the specimens in the upper level. A thermo-regulator and thermometer project into the upper space. The top is pierced by 12 ports flanked by 3/8 in. threaded studs. A test starts when a port is opened and a unit containing a stressed specimen is thrust through it and bolted down against a neoprene gasket. The test chamber is held at 35°C. The gas train, right rear Fig 1, carries ammonia and air continuously to the test chamber. Tank ammonia passes through two reducing valves, a needle valve, a flow meter and into the test chamber. The air from either the plant compressor or a small laboratory compressor passes through wool towers and flow controls to the flow-meter. It then bubbles through water at 34°C and through a heated line to the test chamber. Electrical controls, left rear, Fig 1, provide rectifiers and mercury relays for the test-chamber and humidifier-heating-control circuits and outlets for

Jan 1, 1950

By Zhigang Liang

A carbon free precast block was prepared by using high-alumina fused corundum as aggregate and fused magnesia, and ultra-fine Al2O3 and ultra-fine SiO2 powders as matrix materials. A small linear expansion for the precast block was achieved through spinel formation from the reaction of MgO with Al2O3. The precast block showed a lower apparent porosity, higher hot modulus of rupture and better slag corrosion resistance compared to the traditional Al2O3-MgO-C brick. Moreover, the practical application of the precast block to the ladle lining proved it to possess a better thermal insulation which could effectively prevent the temperature drop of molten steel during the refining process. It can be predicted that the carbon free precast block could possibly be accepted as a new type of ladle lining material for the production of low-carbon and ultra-low-carbon steel.

Jan 1, 2009

Valuers of mineral properties should be aware that accountants are a major user of their opinions of value. Reliance by accountants can range from obtaining comfort that book values in balance sheets are not overstated to establishing values by which to assess the fairness of a takeover offer. Accountants using mineral property valuations clearly can't be expected to have the same level of expertise as the valuer and ""second guess"" the valuation. But they do have an obligation, under the ASC guidelines and their own professional standards, to'check the logic and reasonableness of the valuation before being able to rely on it. This means reviewing the valuation report for general sensibility, discussing the methodologies and assumptions with the valuer and being satisfied as to his competence and independence. This paper outlines how accountants use mineral property valuations, the level of scrutiny applied to such valuations and the problems commonly encountered in practice by accountants seeking to rely on them. The paper also explains how values of-mineral properties are established in company balance sheets and why these often differ, quite validly, from fair market values.

Jan 1, 1994

The Anaconda Copper Company reportedly reached an exclusive agreement with Cook Inlet Region, Inc., to explore 24 million acres in south-central Alaska and to share equally with Cook the proceeds of any mineral discovery. According to an Anaconda geologist, "the company is anticipating, based on geologic testing, that it will find significant deposits of copper, lead, and zinc. There is also evidence of the presence of precious metals such as silver and gold, and also strong evidence of strategic minerals such as chrome, platinum, tin, and nickel." Cook Inlet Region, Inc., is owned by 6,500 Alaskan natives. Chile, which has a growing, free-market economy under President Pinochet, reportedly will no longer require companies to obtain prior governmental approval for the exploration and development of new mines.

Jan 1, 1981

By R. Mehta, M. Misra, X. Su

"The conventional methods to assess Acid Mine Drainage (AMD) potential of the waste rocks and tailings are based on wet chemistry and leachability tests. These methods are time consuming and expensive. There is a growing interest to develop alternate techniques to establish the reactivity of acid mine tailings and stability of treated waste forms. The Electrochemical Impedance Spectroscopy (EIS) is a reliable non-invasive technique which can be used for quick estimation of reactivity of the potential acid generating tailings. In this paper the utilization of the EIS technique for the estimation of reactivity of tailings is discussed. EIS can also be used to predict the long term stability of different stabilized waste forms.IntroductionMetal contaminated mine drainage is one of the most persistent environmental problems facing the mining and mineral processing industries today. Of all the mine drainage pollutants, acid mine drainage has become a substantial concern because of the potential long-term environmental implications and the accompanying liabilities. The main source of acid mine drainage is the tailings containing sulfide-ores which are generated during the ore processing. When these sulfide minerals, particularly pyrite and pyrrhotite, are exposed to oxygen and water they begin to oxidize. The initial chemical reactions produce acid and the acid dissolves heavy metals present in the tailings. Rainfall and snow-melt flush the toxic solutions from the waste sites into the downstream environment [1-2]. In addition to mining tailings, several Department of Energy (DOE) sites contain wastes which are contaminated with radionuclides and heavy metals."

Jan 1, 1999