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By R. C. Ellman

This report presents results of a series of tests on grindability of lignites and factors that influence grindability determination. All grindability tests in this investigation were made in the standard Hardgrove test apparatus. In addition to tests on standard samples of equilibrium moisture content, grindability determinations were made on air-and oven-dried samples of lignite representing the complete range of moisture content from normal bed moisture to nearly moisture-free conditions. Grindability index for all tests was calculated both by standard method and by an alternate or "corrected" method of calculation based on directly measured weight of fine-particle material produced in the grindability test. The second method of calculation allows more satisfactorily for loss of moisture during testing of high-moisture samples.

Jan 1, 1955

By D Kent

The introduction of digital technologies into the underground mining industry, in both coal and hard rock mining, has enabled many high bandwidth applications to be adopted by mines.Digital networks based on 802.11 b/g/n open Wi-Fi standards allow for many applications to be run over a single communication backbone. One important application has been tracking personnel and equipment via RFID tags. This tracking application has in turn formed the basis of a Proximity Detection System (PDS) or Collision Avoidance Systems (CAS). The paper discusses the growth in digital technology as the communication backbone in underground mines which has allowed the ‘convergence of technologies’ that has been occurring in the general business world to be available to underground mine operators. Then the paper will focus on the use of the technology in the increasingly important are of risk control around mobile plant underground. The specific use of digital devices for proximity detection, in both hard rock and coal mines, to provide a system that can deliver an additional level of control to the risks associated with people-vehicle interactions underground is discussed. The initial implementation of PDS in the hard rock mining environment is based on two zones of detection, required for large and relatively high speed vehicles. Information will include:•the principles of the underlying technology,•installation learnings and effectiveness, and•change management methodology and issues.The most recent development to integrate Mine Site Technologies (MST) PDS with Frederick Mining Controls’ HazardAvert® System to extend the overall Proximity System’s functionality in hard rock mines and for use in coal mines is overviewed.

Mar 21, 2011

By J. N. Hartley

Samples of ash from the May 18, 1980, eruption of Mt. St. Helens Were collected from several locations in eastern Washington and Montana. The optical microscope and the combined scanning electron microscope with energy dispersive x-ray microprobe were used to determine the composition and mineralogical characteristics of the samples. In addition, a quantitative image analyzer was used to examine the particle size distribution, and x-ray diffraction was used to identify major minerals. Both polished sections and ultra thin sections (less than 5 ~m in thickness) were prepared to study the mineralogical characteristics. The use of ultra thin sections provided access to microstructural detail. Mineralogically, the samples ranged from almost totally glassy to almost totally crystalline. Crystal-line samples were dominated by plagioclase feldspar (andesine) and ortho-pyroxene (hypersthene) with smaller amounts of titaniferous magnetite and hornblende. Nearly all the samples contained from less than 1 to 3 wt% free crystalline silica (quartz, trydimite, or cristobalite).

Jan 1, 1981

By W. C. Holliman

This report on the characteristics of commercial aviation gasolines is one of a series of such reports. It presents compilations of' inspection data furnished on their products by 15 manufacturers of commercial grades of aviation gasoline and special data obtained in Bureau of Mines laboratories on 68 samples of these gasolines. Data are presented for 18 samples of grade 80, 20 of grade 91/98, 21 of grade100/130, and 9 of grade 115/145 aviation fuels. The gasolines are designated January 1948 production, although some of the samples actually were produced at a later date.

Jan 1, 1948

By M. K. Mohanty, H. Akbari, L. A. Ackah

Dry separation was the predominant method of coal cleaning in the United States from the 1930s to 1980s. The application peak of dry separators for cleaning raw coal was in 1965, when about 23.1 Mt of cleaned bituminous coal was produced. The main advantage of dry coal cleaning is the elimination RIWKH GHZDWHULQJ VWDJHV DQG VLJQL¿FDQWO\ UHGXFHG moisture in comparison to wet processing. In addition, developed dust control systems have made dry cleaning method an environmentally friendly process. The largest air-based coal cleaning plant was built in Pennsylvania in 1968 and could clean 1,272 t/h of raw coal sized smaller than 19 mm. This was followed by a decline in dry coal cleaning to less than 3.6 Mt in 1988. Some of the main reasons that shifted coal operations IURPGU\WRZHWSURFHVVLQJZHUHWKHQHHGIRUPRUHHI¿FLHQW separations with lower density cuts, increase in raw coal surIDFHPRLVWXUHVSHFL¿FDOO\LQXQGHUJURXQGPLQLQJWRFRQWURO GXVW ¿QHUSDUWLFOHVL]HUHTXLUHPHQWV LQFUHDVHLQ¿QHVLQUDZ coal from underground mines, and health and safety concerns related to dust and noise (Arnold, Hervol and Leonard III, 1991; Miller, 2011).

By Morrell S

As more and more autogenous and semi-autogenous mills are run in closed circuit with cyclones the limitations that can be imposed by poor grate and pulp lifter design are becoming increasingly apparent. Relevant literature on the subject is al

Jan 1, 1997

By Jaroslav Horskoý, Miroslav Raudenský, Bogdan Filipic, Božidar Sader

This paper describes main elements and practical use of the computational system for automated setting of optimized casting conditions in the continuous casting of steel. The system consists of the heat transfer model of the process, empirical metallurgical criteria, and optimization algorithm. The physical model of the, strand temperature distribution relies on the classical Bennon-Incropera mixture continuum formulation for the convective-diffusive heat transport. Fluid flow effects are considered through enhanced thermal conductivity of the liquid phase. The model is solved by the operator-splitting Crank-Nicolson finite volume version of the Voller-Swaminathan scheme. The solution procedure is coupled with the IDS solidification analysis package. Boundary conditions for the strand cooling rely on combination of the generic and plant-specific mold, spray, and roll heat transfer coefficients ' by coping the effects of the casting speed, casting temperature, casting powder, mold oscillation mode, steel grade, water or air-mist spray type, running water, trapped water on the rolls, and radiation. The caster safety and productivity and the quality of the strand are related to nine empirical metallurgical criteria. The criteria ensure the caster safety and economy as well limit the internal, longitudinal, and transversal surface cracking possibility. The problem of finding optimum casting parameter values is stated as a minimization problem based on the analytical form of the cooling criteria evaluated from the steady-state temperature distribution of the strand. To solve the optimization problem, a genetic algorithm is employed. The algorithm explores process parameters settings heuristically by applying the principles of biological evolution. It starts with a random set of solutions and iteratively improves them through selection and variation. Solutions are evaluated by running the heat transfer model of the process and extracting the values of the empirical metallurgical criteria.

Jan 1, 2000

By Sherwin F. Kelly

NEW trend in geophysics has been uncovered in these depression years, made evident through the thinning cloak of commercial activity, which, in better times, would have completely obscured it. I refer to the increasing use of these methods for geological investigations by federal and state geological surveys. This is a trend that has been gathering momentum not alone in the United States, but abroad as well. Thus, in Poland, the Geological Survey has been playing an increasing role in geophysical work since 1927, and now has- its own geophysical department. The government petroleum producing organization of Argentina has its Geophysical Commission; Brasil boasts a completely equipped geophysical department in its Mineral Production Service; the government of Chile has contracted with commercial companies for geophysical surveys; Peru is planning an intensive program of geophysical prospecting in its petroliferous regions; and Canada has, for several years, cooperated with

Jan 1, 1935

By F. Rivard, M. G. Drouet, W. S. Ruff, P. Carabin

"In both the hot rotary-salt-furnace (RSF) treatment of aluminum dross and the cold ball-millsieving (BMS) treatment of zinc dross, enormous amounts of energy and recoverable metal are wasted and large amounts of greenhouse gas are produced. Such wastes and the environment pollution could be avoided by using the DROSRITE PLUS™ technology. Economic and GHG production comparisons between the presently used industrial treatment processes and DROSRITE PLUS™, supported by over one hundred tests conducted in Canada, the US and Europe, are presented. The savings, with DROSRITE PLUS™, would be about $191 and $418 per MT of aluminum and zinc dross, respectively.INTRODUCTIONDross is a material, which forms on the surface of molten non-ferrous metal, such as aluminum or zinc, during melting, metal holding and handling operations when the molten metal is in contact with a reactive atmosphere. Dross normally consists of metal oxides entraining a considerable quantity of molten free (unreacted) metal, and for economic reasons it is desirable to extract the free metal before discarding the residue. In the case of aluminum dross, recovery of the metal is usually carried out by treating the dross in a furnace at a high temperature (Peterson et al., 2002). By contrast, cold zinc dross is crushed in a ball mill followed by sieving to separate the coarse metal portion from the fine oxide residue.The conventional aluminum dross treatment process, using gas or oil-heated rotary salt furnaces (RSF), is thermally inefficient and environmentally unacceptable because of the salt slag and CO2 produced from the combustion of fossil fuels. In the past several years, a number of salt-free processes have been developed and some of these have found limited commercial use (Gripenberg et al., 1994; Lavoie et al., 1990). In all these dross treatment processes, heating of the cold dross in a rotary furnace requires an external energy input that varies between 375 and 2,500 kWh per (metric) tonne of dross. Molten metal separated during processing of the heated dross is tapped, and the remaining solid residue is discharged from the furnace."

Jan 1, 2012

Las formas de aplicación energética en la industria minera peruana han evolucionado tanto como las fuentes convencionales de generación de energía. En este sentido, el objetivo del texto describe el aporte del carbón y del petróleo como fuentes convencionales de energía y su aprovechamiento para la generación de fuerza en la industria minera del Perú. Asimismo se indican las posibilidades y limitaciones del uso de la energía atómica en dicha generación. El aprovechamiento del carbón como elemento energético no ha logrado superar las espectativas económicas dado su bajo costo de precio en el mercado nacional. De forma que se planteó mejorar el rendimiento de los subproductos derivados de las plantas de carbón, a través de un proceso de homogenización previa, disecado y modificación de los dispositivos en las calderas, asegurando una posible explotación a futuro. A esto se añade el uso de energía eléctrica por medio de la instalación de modernas centrales termoeléctricas a carbón. Respecto de la aplicación de la energía atómica como factor recurrente en la industria minera peruana, se revela un insuficiente rendimiento termodinámico y satisfactorio conlos 700° C necesarios para las turbinas, por lo cual se hace necesario elevar la temperatura a través de una fuente calórifica como el carbón. Mientras que si hablamos de una de las fuentes energéticas de mayor consumo en las mineras como en los plantas hidroeléctricas, el petróleo mantiene su posicionamiento dada la provisión del rendimiento eléctrico. En consecuencia, se busca aprovechar a mayor escala el uso del carbón como combustible en las centrales térmicas mineras por medio de un sistema de control de precio y así establecer una competencia con el petróleo y la generación de la energía nuclear, teniendo en cuenta las condiciones de abastecimiento de energía para su utilización en la región del Altiplano de la zona meridional del país.

Jul 20, 1959

By J-P Franzidis, E V. Manlap

Froth transportation characteristics have a significant impact on the flotation recovery especially in large flotation cells. The probability of an attached particle being recovered into the concentrate depends strongly on the location where it enters the froth phase. A mathematical model for froth transportation in industrial flotation cells was proposed (Zheng et al, 2004). The model has been tested on the experimental data obtained from testwork conducted at the Western Metals Hellyer lead/zinc concentrator. The results show that the model fits the experimental data well, especially when the froth is well developed (ie for a deep froth). The model fitting can be significantly improved by incorporating an air dispersion factor. However, the models encounter some limitation, ie inconsistent prediction at different froth heights, due to change in froth viscosity which cannot be modelled at the present time.

Jan 1, 2005

By Welton J. Wenger

Apparatus for the analytical distillation of crude oils under an artificial pressure of 760 mm. of mercury has been designed and constructed. This apparatus enables laboratories at high altitudes to make Bureau of Mines routine analyses of crude oils with results similar to those obtained by laboratories at sea level. This is especially important for laboratories in the Rocky Mountain region, where barometric pressures of approximately 600 mm of mercury are encountered. During the past 30 years, the ?Bureau of Mines has made several thousand analyses of crude oils from various parts of the United States and from foreign countries. The first part (stage 1) of the distillation for the analysis is made at atmospheric pressure, and as most petroleum laboratories are near sea level, comparable results are obtained ordinarily. However, the increased use of the method by .laboratories at high altitudes has caused difficulty, as the analyses cannot be accurately compared with analyses from laboratories at sea level. For instance, laboratories at 7,200 feet generally report 2 to' 4 percent (based upon the crude oil) more gasoline than sea level laboratories. The use of the pressurized apparatus developed by the writers makes it possible for these high-altitude laboratories to duplicate analyses made at sea level.

Jan 1, 1949

By A. N. Shen

Fe3A1 intermetallics are potential inexpensive candidate for hot applications. In this project, torsion tests on hot-rolled and annealed Fe3A1 (Fe-15.5A1-5.8Cr-1.0Nb¬0.05C) were carried out over the ranges 750-950°C and 0.01~1s-1 . The experimental results showed that when peak stress op>90MPa (LogZ>16s-1 , Z: temperature-compensated strain rate), specimens cracked at randomly low strains. Optical microscopy exhibited original elongated grains and many grain boundary cracks associated with segregation. With op<40MPa (LogZ<16s-&apos;), specimens deformed with low random op but considerably high fracture strains; slowly propagating cracks may explain the reduced flow stress. Optical microscopy showed both elongated grains and equiaxed subgrains with some indications of geometric dynamic recrystallization (gDRX) and of static recrystallization (SRX). Compression tests gave higher stress with little effect of the preexisting cracks. The activation energy Quw of current material in satisfactory torsion and compression tests is about 10% higher than previously published. Fe3A1 has body-centered cubic structure in the experimental range, so it was compared with ferritic stainless steel 434C (Fe- 16.55Cr-0.96Mo-0.21Ni). Constitutive constants and restoration mechanism are compared between these materials. While Fe3A1 is hardly a light metal, it is considerably lighter than most steels. Furthermore, like the other body centered cubic metals (BCC) (a-Fe, ß-Ti, ß-Zr and ß-brass), it exhibits a high degree of dynamic recovery (DRV) like Al alloys, producing easier hot workability than that of austentic stainless steels.

Jan 1, 2007

By James E. Wennen

The through-put and energy efficiency of an autogenous (AG) grinding mill are adversely affected by variability in rock size and rock competency. This applies to both fully autogenous and semi-autogenous (SAG) grinding circuits. In this paper we focus on an approach to overcome the problem of inconsistent mill through-put related to variability in mill feed size and rock competency. The focus is on ores containing hard, competent rock. This approach consists of preparing feed to an autogenous mill that contains 20% coarse media rock and 80% of material crushed to pass 37 mm. Results of pilot-scale testing for two iron-ores will be presented to show that a 10% to 12% reduction in unit energy consumption is possible with prepared feed, compared with feeding the mill with conventional primary crusher discharge.

Jan 1, 2012

By R. J. Kuczynski

The U.S. Bureau of Mines operated a 2,000-g (4.4-lb) batch process development unit for recovering platinum-group metals (PGM) from automobile catalysts. Virgin monolith, used pellet, and used monolith catalyst samples were tested. Leaching twice with 1-pct sodium cyanide (NaCN) solution at 1600 C for 1 h dissolved more than 95 pct of the PGM from virgin catalysts and more than 90 pct from used pellet catalysts. More than 85 pct of the PGM was dissolved from used monolith catalysts when a third autoclave step was added. Solid PGM concentrates containing more than 99.8 pct of the dissolved PGM and analyzing greater than 70 pct PGM were recovered by heating the pregnant leach solutions from virgin catalysts to 2500 C and used catalyst to 2750 C for 1 h. The solution after heating contained less than 0.2 ppm. total cyanide. The virgin residues passed the EPA Extraction Procedure Toxicity Test (EP Tox Test), the EPA Toxicity Characteristic Leaching Procedure (TCLP), and the California Waste Extraction Test (WET) for all elements except Ba. Adding sodium sulfate (Na2S04) to the virgin leach residues reduced the amount of Ba dissolved to an acceptable level. The used leach residues passed the EP Tox Test for all elements but failed the WET and TCLP for Pb.

Jan 1, 2010

By J. W. Furlan

Due to the time consuming nature of froth testing in a laboratory environment, it is required, due to practical limitations, to develop a method of applying a single set of performance test data (Visintainer & Whitlock, 2012) obtained for a single froth pump at a given speed, to a range of froth pump speeds and sizes, % air contents, and liquid viscosities. Head, efficiency, and flow all vary as functions of both liquid viscosity and air content. As such, it is necessary to develop a technique which can be used to interpolate from existing test data in order to predict froth pump performance for pumps of various sizes running at variable speeds. Details of the technique developed in order to achieve this goal as well as the insights gained from analysis of the resulting regressions are discussed. Additionally, comparisons are made between the performance predictions of this test-derived method and those of the Hydraulic Institute Standard for the effects of liquid viscosity on centrifugal pump performance (ANSI/HI 9.6.7-2010).

Feb 27, 2013

By O. C. Blade

This report on the properties of motor fuels sold through service stations in the United States was made in accordance with a cooperative agreement between the American Petroleum Institute and the Bureau of Mines of the United States Department of the Interior. By agreement with the American Petroleum Institute, identification of the items is confidential. It presents analytical data for 4,680 samples, representing the products of 130 companies. The samples were collected during December 1953 and January and February 1954. As in previous surveys, the gasolines covered by this survey include those from both large and small suppliers. The data were obtained by laboratories of various refiners, motor manufacturers, and chemical companies and submitted to the Bureau of Mines for compilation. A list of the National Motor-Gasoline Survey reports published during the past ten years is given on page 5.

Jan 1, 1954

By Howard L. Hartman

If I told you tonight at the outset that my prognastications for the future of mine ventilation were imparted to me by a palm reader or inspired by a vision, you&apos;d dismiss what I had to say before I said it! If, on the other hand, I told you that my forecasts were the result of an elaborate computer model, derived from a complex algorithm, which in turn relied on finite element analysis -- and the entire projection confirmed by on-site experiments with a turbo hybrid-flow mine fan -- you&apos;d sit up in anticipation and hang on my every word!! All of which places me in a terrible dilemma, because my predictions really lie somewhere in between. My intent is to talk to you out of my background of forty years in mine ventilation, looking ahead to conditions that I expect to prevail in the next fifteen years. You may be curious why I picked an unlikely time span of 55 years for my overview, and my response is that it bridges a career lifetime. "The last forty", of course, corresponds with the period of my professional employment since graduating with a B.S. and M.S. here at Penn State. "The next fifteen" bridges the period I expect (the Lord willing) to remain professionally active -- and coincidently brings us into the beginning of the 21st century. (I must confess to stacking the deck a bit: Since it&apos;s infinitely harder to look ahead than to look behind, I purposely minimized the forecast period and maximized the history! Besides, "forty" and "fifteen" have a nice phonetic ring, perfect 20/20 vision sums to "forty", etc., etc.). With these disclaimers, I&apos;ll invite you to join me now in a fast 55-year overview of mine ventilation, of necessity limited to a broad-brush treatment of the subject. (After all, this is an after-dinner talk, not a marathon!) In each- segment, I&apos;ve selected the seven topics that seem to me of paramount importance: in the first part, seven accomplishments in retrospect, and in the last, seven expectations for the future. (The number "seven" needn&apos;t confound you, either: In the bible, it signifies "wholeness" or "completeness".))

Jan 1, 1987

By E. R. Palowitch

This report is the result of a series of coal-cleaning tests using a dense-medium cone-type washer. Detailed results are given for 2 tests using a magnetite medium and 4 tests using a pulverized-refuse medium. Approximately 120 float-and-sink tests and over 500 separate chemical analyses were made in conjunction with these tests. In these tests higher recovery efficiencies and sharper separations were obtained when using a magnetite medium, especially on coal sizes below one-half inch. When sizes above 1 inch at low specific gravities of separation are cleaned, the pulverized refuse medium compared favorably with the magnetite medium.

Jan 1, 1956

By Mark I. Copeland

Bureau of Mines researchers investigated the combined effect of copper and tin additions on the mechanical properties of hot-rolled steels. Wrought steels containing 0.2 wt-pct C and up to 0.2 and 1.0 wt-pct Sn and Cu, respectively, were made and evaluated by conducting tensile and impact tests and electron-beam microprobe and electron microscopy examination. Tin additions did not significantly affect the tensile properties of steel at different copper contents in the hot-rolled condition. Tin lowered the copper content at which strengthening by copper precipitation normally starts, 0.8 wt-pct, and decreased the strength of steel aged at 1,022° F (550° C). The most adverse effect of tin was lowering the notch toughness of steels at most copper contents.

Jan 1, 1976