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By W. J. Long

As a part of the strategic mineral exploration program, examining engineers of the Bureau of Mines collected samples of ore from four manganese properties in Yavapai, Yuma, Maricopa, and Mohave Counties, Ariz. As all of the ores were too low in grade to be acceptable by manufacturers of ferromanganese beneficiation studies were made to determine the amenability of the ores to concentration.

Jan 1, 1948

By P. G. Shewmon, H. E. Collins

A study has been made to determine the sites at which sulfur adsorption occurs on copper surfaces. measurements were made of the relative torques, Ys, at the intersection of twin boundaries with surfaces near the three low-index orientations, i.e., (100), @lo), and 011), over a range of H2S/H2 ratios. HZS concerztvations j'ro~n 3 to 1500pp)n between 830" and 1050°C were used. It is concluded that sulfur adsorption occurved preferentially though not exclusively at edge sites near the (100) and (110) surfaces in the HzS range — 700 Ppm giving rise to negative torques near these orientations. Beyond this HzS range, adsorption occurred at all sites. Near the (111) surface, 7/y little with HzS concentration up to approxiwzately 75pptn. Above this range, the results indicate adsorption is occurring OH both terrace and edge sites. SCIENTIFIC interest in surfaces and their interactions with a gaseous environment dates back to the beginning of the 19th century. The scientific luminaries of that period—Faraday, Maxwell, Rayleigh, Dewar, and Gibbs—were already concerned about such processes. However, it has only been within the past several decades that adsorption on metal surfaces has been actively studied. This increased interest in adsorption has been brought about by the advent of new and improved experimental techniques and apparatus, e.g., ultrahigh vacuum, and field-emission and ion microscopes. However, most of the work done using these techniques has been carried out at low temperatures. When adsorption studies have been made at either low or high temperatures, they usually gave no indication of the particular surface orientations or type of sites on which adsorption was occurring. In the last few years, there have been a series of studies in which the surface tension, y,, and/or its derivative with respect to orientation, 7, have been studied as a function of orientation and atmosphere.'-7 Nearly all of the work on the relative torque,* ~/y, silver annealed in hydrogen and air.6 Recently Winterbottom and Gjostein" have used a modified and more accurate Mykurian method to determine the y plot of gold in hydrogen The only work in which T/~, has been measured over a range of chemical potentials for a given solute, p2, is that of Robertson and shewmon7 on the Cu-0 system. They measured T/Y, vs Po, (10"" to 10- l3 atm) at 1000°C in various mixtures of Hz0 and HZ. From this work they estimated the value of p2 at which one half of the surface sites are occupied with oxygen, pg, as being in the range 10- l6 to 10- l5 atm of oxygen. They also found that increasing Pa increased the magnitude of ~/y, near the (111) and (100) orientations. This indicates that oxygen is not adsorbed preferentially at step edges, but uniformly over all surface sites. In addition, they did one experiment on sulfur adsorption on copper surfaces, which indicated that sulfur adsorption decreases ~/y, near the (100) orientation, while not affecting ~/y, near the (111). This could be interpreted as indicating that sulfur adsorbs preferentially at step edges near the (100). In this paper the primary objective of the work has been to carry out a study of sulfur adsorption on copper surfaces over a range of temperatures and p,. In conjunction with this work, thermal grooving at grain boundaries has been examined as a method of determining the effect of sulfur adsorption on y,. METHODS Ideally, one would like to have information on the quantity of solute adsorbed on a surface and the types of sites at which it is absorbed as a function of p2. The total quantity adsorbed or the surface excess is given by the thermodynamic equation Thus data on the variation of y, with pz indicates the value of p2 at which adsorption becomes appreciable and the quantity adsorbed. The type of adsorption site is more difficult to deduce but information on this can be obtained from the variation of rz with 8, the angular deviation of the surface orientation. This is obtained from the thermodynamic equationlg Data on t and ys as functions of p2 have been obtained by the following methods. 1) Twin Boundary Grooving—By determining the effect of adsorption on the torque, 7, where T is the variation of surface energy, y,, with orientation, it is possible to obtain some indication as to the preferred sites of adsorption. Experimentally, the torque value measured is the relative torque, 7/ys The twin boundary grooving technique suggested by Mykura'' was used in this study to determine near the three low-index orientations— (loo), (110), and (111). Mykura's equation relates 7 /yS to measurements of the di-

Jan 1, 1967

By Eleuterio Alvino Gutarra

El presente trabajo señala la aplicación del sistema de explotación mecanizada en la mina Baúl de la compañía minera Pativilca. Para ello, se implementó la perforación con anillos para obtener mejores resultados en producción, productividad y costos. Asimismo se describe una reseña geológica, el uso de dicho método, la perforación distribuida en anillos, la voladura, acarreo, extracción, productividad y costos en las minas de tajo abierto.

Nov 8, 1982

By Frederick C. Trutt

A guide to the utilization and development of extensions and modifications to the APL Mine-electrical-system Load-flow Program is presented. These modifications include the development of algorithms to minimize computational operations within the iterative-solution techniques, as well as minimization of the number of required iterations. Extensions to the load-flow program include the development of algorithms for the calculation of balanced faults, simplified specification of fault parameters, optional inclusion of pre-fault currents, and an alternate-solution technique.

Jan 1, 1978

By J. J. Hoeppner

Accurate determination of moisture in coals of various ranks has long been a subject of intensive investigation. Excellent reviews of methods developed over many years are given by Brown (9)4/ and, with experimental comparisons, by Goodman, Gomez, and Parry (11). As pointed out in these and other writings, one of the principal difficulties in assigning absolute merit to one or another procedure is the multiplicity of conditions under which water may exist in coal and the difficulties involved in obtaining sharp separation and distinction between these classes. Gauger (10) states: Water recoverable from coal is obtained from the following sources: (1) Decomposition of organic molecules (sometimes called combined water), (2) surface adsorbed water, (3) capillary condensed water, (4) dissolved water, and (5) water of hydration of inorganic constituents of the coal.

Jan 1, 1956

By Mariano de Córdova

A operação dos altos-fornos com injeção de carvão pulverizado ou gás natural requer uma alta qualidade do coque. Para um custo mínimo do coque, mantendo a qualidade necessária, a escolha de carvões e a formulação da mistura é um tema muito importante. Uma ferramenta amplamente utilizada para o design de misturas é a modelagem, precedido pela caracterização de carvões e seguido de teste no forno piloto. Neste trabalho, revisa-se o desenvolvimento dos modelos, com base la literatura pública. Três etapas cronológicas são levadas em conta, desde os anos sessenta até a atualidade.

Aug 17, 2017

"Mixing phenomena in a bottom blown air-stirred one-seventh water model of CLU (Creusot-Loire Uddeholm) reactor was studie9-using three different configurations of straight circular nozzles fitted axially at the bottom of the vessel. The mixing time has been determined by pH measurements at various gas flow rates, bath heights and nozzle orientations in the presence and in the absence of a second phase.Experimental results reveal that the mixing time decreases with increasing gas flow rate. For a given gas flow rate the mixing time increases non-linearly with increasing bath height. Off-center configuration gives slightly lower mixing times as compared to center configuration. It is found that the contribution of buoyancy to the total stirring energy density is very small, but its contribution increases with increasing bath height. In the presence of an upper oil layer, the mixing time increases significantly for all configurations.IntroductionIn high temperature metallurgical melts mixing is carried out by injection of a gas either from top or bottom of the vessel in order to accelerate the rates of chemical reactions and to promote bath homogenization. When a gas is injected into a liquid through a submerged lance, porous plug or nozzle, the gas, rising as a two phase plume to the surface, imparts momentum to the surrounding liquid and causes gross circulation in the bath which promotes mixing."

Jan 1, 1997

By Jack L. Taylor

WITH the exception of the work of Vogel,&apos; and Rolla and Iandelli, very little information has appeared in the literature on titanium binary systems with the rare earth elements. Rare-earth additions to titanium alloys may possibly parallel the beneficial effects on the physical properties of certain steels. Having this in mind, some knowledge of solubility limits and intermediate phases, if any, would be useful. An investigation of the titanium-rich Ti-Ce system was started. Alloy Preparation The iodide titanium from the New Jersey Zinc Co. and the cerium metal from the Institute for Atomic Research Ames Laboratory used in this work were supplied with the typical analysis shown —iodide titanium: 0.0065 pct Mn, 0.0022 pct Fe, 0.0015 pct Cu, and 0.0042 pct Pb; cerium metal: <0.01 pct Fe, <0.03 pct Si, <0.05 pct Ta, <0.02 pct Pr, <0.03 pct Ca, <0.02 pct Mg, with no trace of Nd, La, or Th. The cerium metal, stored in oil, was washed and scraped just before weighing into capped cups machined from iodide titanium. The cold hearth helium-arc furnace described by Schramm et al3 was used for melting. The alloy buttons from the arc-melted cup were cut in two, mounted, and examined. Homogeneous alloys were demounted and rolled to approximately 1/4-in.sq bars. Sections l/8 in. thick were cut from the bar to provide samples. The Ti-Ce alloy buttons analyzed for cerium were of the following composition: 0.19, 0.36, 0.48, 0.61, 1.15, 2.52, 3.06, 3.70, 4.30, 9.20, 14.26, and 18.50 wt pct. Nominal

Jan 1, 1958

By J. W. Lyman

The U.S. Bureau of Mines investigated methods of separating valuable rare-earth materials from Fe in neodymium iron boron (NdFeB) magnet scrap. A selective oxidation treatment of the scrap oxidized the rare-earth portion while leaving elemental Fe. Magnetic and leaching procedures were tried for separating the metallic Fe and rare-earth oxides, but the extremely fine grain size of the oxidized scrap prevented recovery by either technique. The best separation of rare earths from bulk NdFeB magnet scrap was obtained by dissolution with H2S04 followed by precipitation of recyclable rare-earth salts. By precipitating neodymium-alkali sulfate double salts as an intermediate that can be converted to a variety of useful products, many materials-handling and economic disadvantages found with direct precipitation with fluoride or oxalate were avoided. Iron was removed from magnet leach solutions by precipitation as a jarosite, eliminating a major disposal problem. Research was also conducted with contaminated mixed SmCo5 and NdFeB swarf. Using a flotation-leaching technique allows the SmCo5 to concentrate in the froth, while the grinding-medium contaminant sinks and is removed as tailing. The NdFeB is dissolved by H2S04 during the process.

Jan 1, 2010

By Leandro José de Barros Cardoso

A CSN possui 4 linhas de estanhamento eletrolítico (LEE) com capacidade de produção de 700 kt/ano de Folha de Flandres, nas quais durante o processo de estanhamento podem ocorrer desvios de qualidade que impactam no custo final do produto, afetando diretamente o custo de transformação da folha-de-flandres. Um destes desvios são as manchas superficiais (MS), caracterizadas por manchas na superfície do revestimento da Folha de Flandres que prejudicam o aspecto final do produto. O objetivo deste projeto foi reduzir o índice de desvio NOK por manchas superficiais das Linhas de Estanhamento 5 e 6 de 0,28% para 0,14% até abril de 2013. O projeto foi realizado utilizando a metodologia Lean Seis Sigma, obtida pela união do “Lean Manufacturing”, que visa a eliminação de desperdícios durante o processo produtivo e o Seis Sigma como uma estratégia gerencial que busca a maximização do desempenho dos processos. A metodologia é dividida em cinco etapas: Define, Measure, Analyze, Improve e Control. Após a conclusão do projeto observamos uma redução de 65% no índice de desvio do defeito em relação à média do ano anterior (2012). Com esta redução obtivemos um ganho financeiro de R$212.000,00. Este projeto também serviu como projeto de Certificação de especialista Green Belt.

Aug 8, 2018

By Matheus Porto Trindade, Marcos Menino de Macedo Filho, Isau de Souza Alves Junior, Sandro Griza, Brenno Lima Nascimento, Gustavo Dória Lima

O tratamento de oxidação térmica da liga Ti-6Al-4V foi realizado ao ar a 600 °C durante 2h, 5h e 10 h. O comportamento à fadiga foi analisado e comparado com aquele da liga não tratada. Foi feita caracterização através de análise por microscopia ótica e eletrônica, difração de raios-x e medição da rugosidade. Os resultados do DRX demonstraram crescimento dos picos de rutilo. Verificou-se um aumento na espessura média da camada formada de 0,12 μm para 1,09 μm ao elevar a duração do tratamento de 2 para 10 h. Os resultados apontaram redução de resistência a fadiga de 35 % para amostras oxidadas durante 2 h, 27 % para amostras oxidadas por 5 h e 29 % para as amostras tratadas durante 10 h, em relação ao ensaio com corpos de prova não submetidos ao tratamento. O efeito prejudicial causado pela camada formada após oxidação de 2 h foi tão danoso quanto o causado pela camada formada após 10 h, apesar da diferença entre as espessuras das camadas. A morfologia encontrada nas amostras fraturadas indicou fragilização na superfície das amostras oxidadas, contribuindo para a nucleação de trincas iniciais nos primeiros ciclos de fadiga na camada que favoreceram a propagação de fadiga, independendo da espessura de camada.

Oct 19, 2019

By Thomas A. Phillips

The Bureau of dines present, an economic evaluation of its process for the ferric chloride leaching of chalcopyrite concentrate. In this process, chalcopyrite concentrate is leached with ferric chloride solution to extract copper, which is precipitated from the solution by electrolysis while leaving sulfur in the residue. Spent liquor from electrolysis is treated with oxygen to regenerate the ferric chloride leach solution and the sulfur-laden residue is processed to recover the sulfur. A cost estimate was prepared for a plant capable of processing 600 tons of chalcopyrite concentrate per day, 330 days per year. The fixed capital cost, on an early 1.975 basis is $27,831,600 and the estimated operating cost is 9.9 cents, per pound of copper product. In comparison, the estimated operating cost of a smelter equipped with a citrate process plant to recover sulfur is about 13.6 cents per pound of copper product. No charge for chalcopyrite concentrate or credit for recovered byproducts has been included in either operating cost. The ferric chloride leach process, therefore, appears to be economically attractive.

Jan 1, 1976

IDS: The Company IDS Ingegneria Dei Sistemi, founded in 1980, is a world leader as a high technology solution provider in selected niche defense and civil market sectors ? Private and Independent ? IDS?s Quality System is certified ISO 9001 Ed. 2000 ? IDS has the highest Military Clearance ? Continuously measure (24x7) mine wall movements with sub-millimetric accuracy at long distance (up to 4 Km) ? Provide reliable early warning for progressive slope movements potentially leading to mining wall failures ?Map the long term evolution of slow moving slopes to get a better knowledge of the rock mass strength

Aug 1, 2013

By Juel H. Stears

Research was done to determine if a hydraulically operated penetrometer developed by the Bureau of Mines could be used to estimate the roof-bolt anchorage capacity of mine roof rock. Tests were conducted both in the laboratory using cement cylinders and underground in shale rock. Hardness readings were measured by the penetrometer around the periphery of the bolt holes at the anchorage horizon. Roof bolts Nere then installed and subjected to an anchorage test. The results showed that the penetrometer readings could be used to determine the optimum stratum for roof-bolt anchorage but could not be used to make an accurate estimate of the anchorage capacity.

Jan 1, 1965

By D. Komljenovic, E. Lafontaine, J. Paraszczak

Availability of the production equipment used in underground mines has a substantial impact on production costs and, thus, on mine profitability. Appropriate collection of pertinent data and information, as well as use of adequate performance measures and their analyses, can help mine operators identify cost-effective opportunities to improve equipment availability. This paper presents study results aimed at reviewing and analyzing means and measures used to quantify equipment availability and its contributing factors (reliability, maintainability and maintenance support) in several Canadian underground mines. It overviews sources, as well as quality and quantity of relevant data and information, and examines performance measures and their definitions, as applied to surveyed mines. Problems concerning data acquisition and meaningfulness of the performance measures are discussed. The paper concludes with some suggestions and recommendations concerning several aspects of equipment availability assessment. Evidence suggests that the latter may become a more useful tool for mine operators in their efforts to reduce production cost.

Jan 1, 2008

By A. W. Decora

Gas-liquid chromatography has been applied to separating basic nitrogen compounds, such as pyridines and amines. Close-boiling compounds have been separated by exploiting structural and polarity differences, using selective liquid substrates dispersed on specially prepared solid supports. Development of these special supports was necessary in order to obtain symmetric peaks for basic nitrogen compounds; solution of this problem was important in applying gas-liquid chromatography to the analysis of basic nitrogen compounds found in shale oil. Attempts to analyze shale-oil tar bases by conventional gas-liquid chromatographic techniques, using Chromosorb4/ or Celite 545 as the support for a nonpolar liquid substrate, resulted in asymmetric peaks. These asymmetries were caused by adsorption of sample vapors on the solid support. Symmetric peaks were obtained when strongly polar liquid substrates were used on either Chromosorb or Celite. However, a solid support giving symmetric peaks only with strong polar substrates restricts the choice of substrate, and frequently, desired separations cannot be achieved.

Jan 1, 1961

By W. H. Carrington, A. C. Richardson

"INTRODUCTION The Powhatan mine of the Franklin Coal Mining Co. is located in the western part of Jefferson County, Ala., on the Louisville and Nashville Railroad, 40 miles west of Birmingham. The Mary Lee bed at this point yields coal with fair coking qualities, but with an ash content as mined so high as to prohibit its use in the production of metallurgical coke. At present the entire output of the mine is washed in single-compartment jigs and marketed as locomotive and domestic fuel.Figure 1 gives a typical seam section of the Mary Lee bed at the Powhatan mine. This section shows that the bed is divided by rock partings into three benches. In many parts of the mine, particularly in the older workings the roof rock is so weak that it can not be held without excessive timbering. This condition has restricted the operation in many parts of the mins to the middle and bottom benches of coal. The 6 inches of draw rock between the top and middle benches is very strong and makes an excellent roof requiring only a normal amount of timbering to support it. In the newer workings of the mine the character of the rock above the top bench is strong and it is believed that in the future it will be possible to work all three benches. This study was undertaken for the purpose of determining the washing characteristics of the Mary Lee bed at Powhatan and the effect on these characteris-tics of including or omitting the coal from the top bench. It was also the purpose of the study to show whether it would be possible to produce a washed product sufficiently low in ash to be used for the manufacture of metallurgical coke. This paper is one of a series of reports on the washability of Alabama coals which is being prepared by the U. S. Bureau of Mines and tin University of Alabama. With the cooperation of the coal producers of Alabama. It contains the results of screen sizing and float-and-sink tests of representative samples of run-of-mine coal, and the results of table tests on the minus 3/16-inch sizes of the raw coal."

Apr 1, 1933

By Frank W. Dickson, George Tunell

Five hot spring areas of the western United States show evidences of present day deposition of HgS; two also show evidences of accompanying Sb2S3 deposition. Sulfide minerals are depositing at or near the surface from hot waters that differ for each spring ai:ea in amount and kinds of dissolved matter. All the springs contain dissolved substances that act as buffering agents and that cause increased alkalinity with increasing temperature. Transport of Sb2S3 is possible in H2O and in boron and sulfide solutions. Increasing alkalinity and temperature enhance stibnite solubility. Quantitatively important transport of HgS appears restricted to alkaline sulfide solutions that contain HgS2=. Elemental mercury probably forms in deep hot waters because HgS breaks down into mercury and sulfur above 200°C, and free S is removed by reaction with water. Elemental mercury should accompany HgS2= in solutions that were at 200°C or higher. Cinnabar deposits from saturated alkaline sulfide solutions because of combinations of temperature decrease, dilution, oxidation, and reactions with wall rock: Amedee Hot Springs, Boiling Springs, and Coso Hot Springs are areas in which HgS is the only sulfide deposited. Hot waters at Amedee and Boiling Springs are supersaturated with HgS or transport colloidal HgS. Steamboat Springs waters deposit mainly silica and stibnite, but they have deposited HgS recently. Sulphur Bank waters deposit mostly stibnite and some HgS. The hot-spring waters of all springs represent highly modified deep water. Field and laboratory studies support the concept of transport of HgS in moderately alkaline sulfide solutions as HgS2=. Fluctuating deposition of stibnite and cinnabar reflects availability of sulfide or variations in deep-source HgS and Sb,S,. Silica and HgS dissolve mutually in alkaline sulfide solutions, and cinnabar and quartz would be expected to deposit simultaneously. Free mercury given off by hot-spring waters would impregnate country rocks.

Jan 1, 1968

By Herty, C. H.

No attempt will be made here to review the previous work done by investigators on the general subject of inclusions, because it was discussed sufficiently in an early cooperative bulletin of this series (No. 36, 1928), and reference was then made to general bibliographies. The work described in this present bulletin deals directly with the study of the mechanism of deoxidation of steel with aluminum and the formation of inclusions containing alumina. Unquestion- ably, such inclusions are encountered in most steel-making practices and little has been done to determine their characteristics. Aluminum is used to ensure rapid deoxidation during the solidification stages of the steel. For this reason the possibilities of inclusion elimination are slight and alumina-containing particles will undoubtedly be present in the ingot. Besides this common practice, aluminum is often used in the ladle with other deoxidizing agents such as silicon and manganese. Ladle additions of aluminum are made to rimming steels to obtain the correct partial deoxidation desired in this type of steel. In killed steels the aluminum is added to ensure soundness, as far as blowholes are concerned, in the ingot. In either rimmed or killed steels, alumina or alumina-containing inclusions are found therein, the amount and type depending on the oxidation of the metal, the amount of aluminum added, and the addition of other deoxidizers.

Jan 1, 1957

By F. D. Stevenson

Thermodynamic properties of metal halides and, in particular, vapor pressures have become of great importance in recent years owing to increased application of chemical processing to extraction of metals from their ores. Vapor pressure data serve not only as a valuable source of latent heat of vaporization and fusion values but also differences in metal-halide vapor pressures often provide the basis for their separation by conventional mass transfer operations. This literature search was made to provide a ready reference to experimental vapor-pressure data of metal halides and oxyhalides. Results are reported in two main sections: (1) A tabulation of vapor- pressure references for each of the metal halides (listed by metal) for which actual experimental data are reported (table 1), and (2) a bibliography of the citations. Metal halides and oxyhalides are listed by chemical formula and chemical name, based on the stock4 system. To facilitate location of the references, a listing of the journal titles and their abbreviations follows the bibliography.

Jan 1, 1963