Search Documents

By A. L. Foote

This is the final report of work accomplished during 1973-75 under U. S. Bureau of Mines Contract No. H0242015, "System for Handling Underground Mine Supplies and Materials." The purpose of the contract was to develop a mechanical device which could safely perform handling tasks that are normally done manually in underground bituminous coal mines. The report discusses studies leading to construct-ion of a battery-operated, three-wheel vehicle with a six-degree-of-freedom manipulator. Supportive design studies included collection and analysis of production, manual functions, and injury data on the underground bituminous coal mining industry. Transfer tasks in section storage and working places were the prime candidates for mechanical handling. Functional specifications were developed for two handling devices (one to handle existing unit loads and one to handle repackaged unit loads) and for a vehicle to mount the handling device. Design concepts for nine different handling devices were developed and a cost/benefit evaluation made for each. Detail design, capital and operating costs, and method improvement savings data were developed for two battery-operated vehicles and for two different manipulators. The three-wheel vehicle with anthropomorphic manipulator was chosen for development.

Jan 1, 1978

By Xingjian Gao

The mechanical properties of a low carbon low alloy steel in the austenite and _-ferrite regions have been examined by thermal-tensile tests using a Gleeble-1500D system at temperatures in the range 600oC to 1300oC and at a strain rate of 10-3/s; these being the conditions that apply to the unbending operation during the continuous casting of steel. The yield strength and tensile strength of steel decreased with increasing test temperature and the embrittlement zone occurred in the temperature range 800oC to 970oC. In the embrittlement zone, the fracture surfaces and microstructures of the tensile specimens were examined by scanning electron microscope. The results showed that the cause of the embrittlement at 950oC in which the minimum %R of A was around 36% is the second phase particles precipitated along the _ grain boundary during deformation leading to inter-granular brittle fracture.

Jan 1, 2010

By George Comstock

IT seems a common opinion among metallographists that all light-gray inclusions seen with the microscope in polished sections of steel are manganese sulphide. Examples of this belief are continually appearing, as for instance in the paper by Dr. Henry Fay on manganese sulphide as a source of danger in steel rails,1 and in Lieutenant-Commander Cook's paper on Metallography of Steel for U S. Naval Ordnance.2 Slate FIG. 1-TRANSVERSE VIEW OF THE EDGE OF A SMALL HOT-ROLLED STEEL ROD. ETCHED WITH PICRIC ACID. X 200. colored inclusions are considered to be silicates, and dove-gray inclusions, manganese sulphide. To show the danger in the latter unqualified assumption, it should be sufficient to examine the edge of any piece of steel that is covered with a fairly thick scale, and that has been polished in such a way as to prevent the scale from breaking away entirely below the polished surface. This can be done by protecting the scaled edge of

Jan 12, 1916

In 2002 the authors updated the MFire model developed by the US Bureau of Mines. MineFire, developed by Mine Ventilation Services, Inc. (MVS), uses the MFire model to perform mine fire simulations on typical mine ventilation networks. The MineFire program is capable of producing visual schematics and other analysis tools for input and output of the MFire model. The MFire model, however, was limited to 500 branches and 10 fans. This paper discusses the newly modified MFire model that is now capable of modeling over 5000 branches and over 400 fans among other expansions and improvements. Given the long history and proven track record of MFire, the expansion did not modify the core calculation methods or results. This paper focuses on a general discussion of the MFire program and issues encountered in expansion of the algorithm. An example large network with simulation results is discussed.

Jan 1, 2011

By Lucien Eaton

THE use of filling in mines is less common in the United States than it is in Europe, where in some places it is required by law. In most cases the filling is placed by hand, and the material used for this purpose is the waste from development and that sorted from the ore in the stopes. When these sources provide an insufficient supply, additional rock must be quarried on surface or mined underground, or some other material :st be used. In different parts of the world sand, clay, gravel, culm, nulated slag, mill tailings, and even ashes, have been used as filling material in place of or in conjunction with rock. Of all the materials used for filling the best is probably clean sand. Gravel, finely crushed rock, granulated slag and coarse mill tailings are almost as good, and the methods used for placing and confining sand will apply equally well to any of these. The advantages of sand are its comparatively slight compressibility and the ease, economy and convenience with which it may be placed. On account of the voids, which necessarily occur in fills made of coarse waste, such fills will compress 10 to 25 per cent before they develop their full strength, whereas clean sand seldom compresses more than 5 per cent. Sand is especially desirable when practically complete filling is required, and sand derived from mill tailings, especially when not thoroughly cleaned, has been remarkably effective in sealing off and extinguishing mine fires. When natural sand is available on surface, or when it can be obtained from the mill tailings or tailings dump, the cost of using this material for fill will probably be considerably less than that of rock. In this paper it is not proposed to discuss all methods of filling, butt to describe some of the methods used for placing sand fill and to make a brief comparison of their merits.

Jan 1, 1932

By C. Velásquez, W. Bergholz, C. Spence, P. Lind

NuevaUnión SpA (NuevaUnión) is a development project located in the Huasco province of the Atacama region of Chile. It is held in a joint venture company owned 50:50 by Teck Resources Limited (Teck) and Newmont Goldcorp. It includes the Cu-Mo Relincho deposit and the Cu-Au La Fortuna deposit, with plans to utilise a single concentrator to be built at the Relincho site. The Relincho site is at an altitude of 2,000 masl and is 40 km from the La Fortuna site which is at an altitude of 4,100 masl. The project is currently completing a Feasibility Study and is reviewing equipment selection and flowsheet options. This paper is based on the current thinking, and design decisions will be finalized at the completion of the Feasibility Study. NuevaUnión is currently planning for phased operation, processing Relincho ore at 104 ktpd followed by processing ore from La Fortuna at 116 ktpd. Plans for the third phase include doubling the main processing lines and returning to Relincho ore at a processing rate of 208 ktpd. The NuevaUnión concentrator will incorporate comminution and flotation circuits that are being designed to maximize the overall economic value of the combined ore deposits. Major ore characteristics differ between the two ore bodies, such as ore competency, grindability, liberation grind size, pulp rheology, tailings properties, minerals and metals of value, as well as gangue mineralogy. Mineral processing choices have been made to optimise value from each deposit and the combined project. INTRODUCTION Between 2010 and 2013, two significant mining projects were being developed in Chile: Goldcorp’s El Morro project had recently finalized a Feasibility Study and, in 2011, had received its environmental approval for construction; and Teck Resources Limited’s (Teck) Relincho project was finalizing a Feasibility Study and preparing its Environmental Impact Study. Both projects were: Geographically close, at only 40 km apart. Considering similar infrastructure. Each was planning to have its own concentrator, tailings management facility, high voltage power line, port, concentrate transport system, seawater desalination plant and pumping system to mine site.

Jan 1, 2019

By R. V. Ramani

"A computer simulation model of a dragline has beer developed for the study of alternative dragline deployment schemes for varying geological and mining conditions. In this paper, the mathematical aspects of the model, the input data and output results are discussed. An application of the model to a coal mine in eastern Kentucky is presented.IntroductionDraglines are very productive machines. To extend their operating ranges, they are operated in several modes such as advance benching, key cut, extended benching and pullback. Unfortunately, these variations result in low machine productivities. Appropriate methods to operate these machines must be developed on the basis of detailed analyses of dragline performance under varying geological and mining conditions. There are several standard engineering procedures for the selection of dragline, and design of a dragline pit (Ramani, Iroegbu and Manula, 1976). However, the complex interrelationship which exists among equipment, methods and natural conditions can be quantified only through orderly and systematic experiments.Computer simulation is well suited to studying these types of equipment selection and method layout problems. Several alternatives can be analyzed in a relatively short time by the modification of input variables. Also, the application of computer simulation models can significantly reduce the manpower and cost required for such analysis."

Jan 1, 1985

By K. Fleck

Energy West Mining Company (EWMC) has implemented a geologic program for improving stability and support requirements along deep two-entry longwall gateroads at its Deer Creek Mine operations located near Huntington, Utah. Together with geotechnical monitoring and concurrent review of mine seismicity in cooperation with MTI staff, it has become possible to improve longwall layout designs for two seam extraction of the Hiawatha and Blind Canyon seams. The geologic program consists of surface and in-mine exploration drilling, surface and in-mine geologic mapping, rock mechanics testing and detailed measurements of changes in depositional and structural conditions during development of every longwall gateroad. The geotechnical program consists of underground measurements at seven locations in two neighboring mining districts located in the Hiawatha and Blind Canyon coal seams under moderate to deep cover. Within the last five years, additional measurements, including data on seismicity and face conditions, have been incorporated into the data collection program for verifying the insitu coal strength and load transfer mechanisms for improving two-seam designs and support systems. Geologic mapping results are also used to predict local stability of headgate and tailgate entries, combining mine roof mapping, stratigraphic profiles of the coal and roof, and depth-of-cover information and dual-seam mine overlays, for use by operations personnel in planning roof and rib support for the retreating longwall sections.

Jan 1, 2012

By Robert F. Shurtz

This paper suggests that pre-occupation with the random process model notised by geostatisticians may result in neglect of more promising techniques, especially since the random process model does not appear to be essential to current geostatistical procedures. This point of view is emphasized pictorially. To emphasize the potential of new techniques a simple application of the conventional Brownian function is described. The probabilities estimated in this truly random way are different from those estimated by Kriging

Jan 1, 1980

By Jeff Jackson, Paul Axtell, David Graham

The Montana Department of Transportation recently awarded a contract to construct a replacement bridge across the Clark Fork River in Heron, MT. Both abutments and both intermediate bridge bents were to be founded on 6-ft and 8-ft diameter, permanently cased drilled shafts with rock sockets, respectively. Two drilled shafts per substructure location were designed for a total of eight drilled shafts. The original design included 6-ft diameter drilled shafts at the abutments but the Contractor elected to submit a Value Engineering proposal that increased them to 8-ft diameter. On the basis of the subsurface exploration program, extremely challenging subsurface conditions were known to exist, including the potential presence of large boulders within the predominantly sand and gravel soil matrix. The successful bidder elected to use an oscillator to install the permanent casing to the top of bedrock, while simultaneously removing the spoils from inside the casing with a clam-grab. On seven of the eight shafts, this approach worked well. Unfortunately, on one of the shafts, the casing met refusal on one or more boulders encountered in the predominantly sand and gravel soil overburden. Following several attempts, and despite several variations of approaches, it was determined that the casing could not be advanced beyond the obstruction without unacceptable risks to the pile-supported temporary work trestle (i.e., loss of soil and reduction in pile capacity for the foundations supporting the work trestle). To mitigate the problematic drilled shaft, a unique solution was designed and successfully constructed. The solution involved the construction of seven 16-in diameter micropiles constructed within the confines of the obstructed casing. The micropiles were drilled to bedrock through the sand, gravel, and boulders and include rock sockets to satisfy axial design requirements. The micropile casing thickness, grade and grout strength were designed to provide adequate flexural strength as well as to satisfy other design requirements. Upon completion of the micropile installation, the upper portion of the drilled shaft above the boulders and within the permanent casing was constructed as usual. This paper discusses the difficult subsurface conditions at the site, the drilled shaft construction difficulties, and the design and construction of the micropile solution.

Jan 1, 2018

By T. J. Driscoll

Methane-air mixtures can ignite as a result of sparking or rubbing of materials, particularly by impact involving light alloys and rusted steel where an exothermic thermite reaction can occur. This report reviews the published literature and describes a new method utilized by the Bureau of Mines for studying the processes occurring during collisions of light metals with rusted steels. The method involves measuring the spectra of sparks and explosions in methane-air mixtures using a photodiode array. Initial results obtained using magnesium and aluminum alloy 6061-T651 projectiles striking rusted steel are reported. These results indicate that the continuous parts of the spectra show a larger intensity for incendive sparks compared with nonincendive sparks, with the largest relative change in the higher energy, ultraviolet region. An unexpected shift of the intensity maximum for the continuous parts of the spectra towards the infrared region was observed for the more incendive sparks. Evaluation of rusted steel samples with electron microscopy, energy-dispersive X-ray spectrography, and Auger electron spectroscopy after they had been impacted by aluminum alloys indicated that aluminum was transferred to the steel in the form of islands that became larger as a function of increasing projectile velocity.

Jan 1, 1982

By C. H. Manney

This report deals with the feasibility of the use of vocoders as an integral part of a mine electromagnetic voice communication system. Limitations imposed by the nature of the transmission path, background noise and equipment are examined. Some properties of vocoders and apparent advantages of the use of vocoders in a mine communication are discussed. The conclusion is reached that the man-made noise level will ultimately determine the workability of such a system.

Jan 1, 1972

Were it simply a matter of extracting tin from the simple tin sulphide, the proposition would undoubtedly be simple enough. When, however, other valuable metallic sulphides are combined with the tin, and it is required to separate these intomarketable products, then the proposition becomes somewhat complex, and such is the case with the class of material of which I am about to write. The locality where it occurs is Howell, New South Wales, and chiefly at the Conrad Silver-Lead Mine. The tin sulphide occurs chemically alloyed with copper, iron and other metals associated with galena, pyrites, mispickel, blende and silver sulphide in varying proportions, and generally in a gangue of highly crystallised quartz.Several varieties of tin sulphides occur, and from the following analyses of three minerals, these being specimens specially selected free from foreign matters, it will be seen that the chemical composition is somewhat complex.

Jan 1, 1902

By Jae R. Lee

Keywords: Self-propagating high temperature synthesis, AlN, Powder synthesis The particle size and shape effects of starting raw powders on the synthesis of aluminum nitride by self-propagating high temperature technique under high nitrogen pressure were investigated with various AlN diluents and Al reactants. It was found that the structure of beds of the starting raw particles largely affected the pore channels for nitrogen gas infiltration as well as the passages for combustion propagation before and during the reaction, resulting in the morphology and purity changes of the synthesized products. The AlN product of purity over 98% with about 30 microns was obtained.

Jan 1, 2005

By Warren E. Morrison

INCREASED production and utilization of minerals fuels and power accompanied the overall expansion in U.S. economic activity during 1963, which saw continued advances toward higher production, employment, and purchasing power. During 1963, record levels of wages, profits, and consumption were attained, while costs and prices maintained the stability exhibited throughout most of the recovery period. Expanding industrial production, the average index of which went from 118.3 in 1962 to 124.3 in 1963, narrowed the gap of unused manufacturing capacity to an estimated 5 percent. Gross national product (GNP), another major indicator of economic activity, reached a record level of $583.9 million (current dollars) during the year, this being $27.7 billion, or 4.9 percent above 1962. These achievements were somewhat marred by unemployment, which remained at 5.5 percent of the labor force in 1963, and the continued deficit in the U.S. balance of payments. Against this general background, total national consumption of energy resources for the year was equivalent to 49,816 trillion British thermal units (Btu), an increase of 4.2 percent over 1962. This represented a somewhat lower rate of growth than for GNP during the year.

Jan 1, 1964

By P. K. Sahoo, C. R. Ray, S. S. Rao

Good operation of Soderberg electrodes is dependent upon high quality electrode paste coupled with better electrode management procedures. Without having a good electrode operation, it is not possible to obtain the best outcome from the furnace. In other words that is a good way to say how important the proper electrode operation is. Good electrode performance depends on the slipping rate and current levels, which decides the shape of the baking curve at the level of just below the contact clamps. Negative curvature of baking zone in the central part is considered dangerous because shrinkage takes place outwardly creating abnormal stresses in the electrode. Soft breakages occur when the baking zone comes below the clamps and the casing cannot take the current. This paper deals with various factors affecting baking characteristics leading to soft breakages and also presents case studies in a closed 48MVA furnace with smelting for charge chrome. In case studies in a closed furnace, it has happened that the energy for baking at the low current operation before breakage has been lower than the actual slipping has demanded. At low current there should not be problem, but a problem can occur when the current for some period is raised above the current carrying capacity of the casing. So data for electrode operation in actual period was studied and presented in this paper.

Jan 1, 2007

By William H. Schiffbauer

The Bureau of Mines is conducting research that is aimed at making the mining industry more efficient in term of both productivity and the health and safety of the worker. As part of this research the Bureau of Mines has integrated a testbed composed of computer and related peripheral hardware to form an intelligent base for performing autonomous mining machine experiments. Although this particular application was con- figured for use on a Joy 16 CM mining machine, its generic structure facilitates its attachment to a variety of mining machine types. The multitasking multiuser computer can be set up for other applications by changing a bubble memory cartridge. The Joy 16 CM implementation includes 96 digital input-output (1-0) ports, 32 analog inputs, 8 analog outputs, 2 serial data channels, and 1 printer port. Operation of the machine can be performed either through a local terminal or remotely through a modem hookup. This report describes a testbed for autonomous mining machine experiments (TAMME)--its hardware, software, and complete system integration--so that it can be used as a foundation for other applications.

Jan 1, 1988

By Aníbal Gastañaga

En la industria minera, la silicosis se presenta como una enfermedad ocupacional que incapacita total o parcialmente al trabajador labor física, incidiendo directamente en la marcha socio-económica del país, puesto que entre los incapacitados, existe un alto porcentaje de personal calificado, con experiencia valiosa y aptitudes especiales que adquirieron la enfermedad producto de años de trabajo y adiestramiento adecuado. En ese sentido, el presente texto describe los casos de silicosis, monto de indemmizaciones de 1948 - 1966.

May 1, 1968

By P L. McCarthy

In an environment of accelerating capital costs, limited capital availability and strongly cyclic metal prices, there is a difference between a robust mining and processing operation and one that would maximise shareholder returns in an idealised world. A higher cut-off grade policy is likely to improve operating margins and may reduce the scale of operations and thus limit capital exposure. This will leave some metal in the ground, but it is marginal material which carries the greatest cost and risk exposures. Where do we draw the line?CITATION:McCarthy, P L, 2013. Is bigger better? Building market resilience into process plant design, in Proceedings MetPlant 2013 , pp 66-70 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Jul 15, 2013

By M. R. Samis

The great variability of mineral and energy prices has motivated some governments to incorporate a windfall profits tax into their mineral taxation regimes. Windfall profits taxes are a means for governments to capture additional mineral revenue when mineral prices are considered higher than some historic level. Governments need to be aware of the effects of such contingent taxes on the exploration, development and operating decisions of mining companies. Mining companies need to be able to calculate the full impact of windfall profits taxes on the economics of their projects. This paper examines the valuation of a multi-phase copper-gold project in the presence of a windfall profits tax. Real options Monte Carlo simulation is used to characterise the different exposures of the mine owner and of the government to the risky cash flow streams that they receive from the project. The results highlight that Monte Carlo simulation paired with the real option valuation method is able to account appropriately for the differing risk exposures, while the traditional discounted cash flow valuation model is not. Our key conclusion for governments and mining companies is that the impact of contingent tax and royalty terms can and should be assessed using advanced valuation techniques, and the results used to improve contract designs under the constraint of actual and perceived fiscal system stability.

Jan 1, 2007