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By T. G. Legare

It is now well documented that trace amounts of silver, gold, and platinum group metals occur in certain geothermal brine deposits. A significant body of literature has been generated over the last twenty years which describes attempts to quantify the frequency and levels of these precious metals in the brines. This literature is often confusing and contradictory. For example Barnea 1 states that the Salton Sea geothermal field carries 2 ppm gold, yet more recent data by workers at Lawrence Livermore National Laboratory2 (LLNL) concludes that the gold level in Salton Sea brine is <0.07 ppb. They report a platinum level in one well of 55 ppb. This apparent contradiction may be explained by sampling source and technique, but is most probably explained by difference in analytical technique. Analytical techniques and problems will be discussed in the next section.

Jan 1, 1985

Considerable attention has been given to the restoration of low-level radioactive (<1000 pCl/g) sites contaminated during the early years of the atomic energy program. Current clean-up activities which involve the relocation of contaminated soils to licensed disposal sites have been shown to be very costly due to the large volumes of soils which must be excavated, transported and stored. Recent characterization studies conducted at Virginia Tech suggest that the volume of soil requiring disposal can be greatly reduced using mineral processing techniques such as classification, density separation and froth flotation. This article discusses the application of these technologies for soil remediation and describes a conceptual flowsheet for treating soil samples from two contaminated sites.

Jan 1, 1997

By Clarence Zener

THE internal friction of nonferrous metals vibrating at low stress amplitudes has so far always been successfully interpreted in terms of inhomogeneities of one sort or another. Examples are the fluctuation of stress across a specimen vibrating transversely,1,2,3 the stress inhomogeneities due to the elastic anisotropy and partial random orientation of the individual crystallites,4,5 localized weak regions introduced by cold-working,6,7 grain boundaries and possibly twinning planes.8,9 Perfect single crystals are, by definition, homogeneous. Actual single crystals usually, perhaps always, contains some imperfections. The present investigation. was undertaken to determine whether the internal friction of single crystals may likewise be attributed to inhomogeneities. This study was made possible through the gift of a large single crystal of 70-30 alpha brass by H. L. Burghoff, of the Chase Brass and Copper Co. The specimen, ½ in. in diameter and 10 in. long, was similar to samples previously described by Mr. Burghoff.10 EXPERIMENTAL METHOD The experimental method used has previously been described in Institute papers.5,6,9 The measure of internal friction adopted here, 1/Q, is (1/p) X the logarithmic decrement, a measure used by some writers, and is also (1/2p) X the specific damping capacity, a measure used by other writers. In all measurements the stress level was kept so low that the measurements were independent of stress level. In all measurements in which the temperature was varied, observations were made as the specimen slowly cooled from its highest temperature. The specimen was vibrated transversely. Observations were made at the funda¬mental frequency and at the first overtone, of about 620 and 1710 cycles per second, respectively. No attempt was made to avoid acoustical losses. EXPERIMENTAL RESULTS The specimen was annealed for several hours at 450°C. The temperature dependence of the internal friction was then determined from room temperature to 400°C. As shown in Fig. 1, the internal friction increased by only a factor of 2 from room temperature to 300°C., then by a factor of l00 during the next 100° interval. These measurements are consistent with the view that the observed internal friction is the superposition of two distinct parts. One, dominant at room temperature, is nearly independent of temperature. This part may be accounted for by acoustical losses and by transverse thermal currents. It was not further investigated. The second part, when plotted in the manner of Fig. I, lies upon a straight line. Therefore it has a heat of activation H; i.e., it varies with temperature as Internal friction e~H/RT [I]

Jan 1, 1942

By Frank A. Peters

This Bureau of Mines report is the second of a series of process evaluations planned to determine the relative processing costs of producing metallurgical-grade alumina from low-grade aluminous materials. Included in these evaluations are recommendations for additional research and development to improve the processes and to lower their costs. The design for each process is based on published work. The processes considered in this report are designed to extract alumina as aluminum chloride from calcined clay with 20 percent hydrochloric acid and to remove the silica residue by filtration. Iron is removed by one of the following processes: Isopropyl ether extraction, in which iron chloride is extracted before decomposing the aluminum chloride; gas precipitation, in which the aluminum chloride is precipitated with hydrogen chloride while leaving the iron chloride in solution; gas precipitation-isopropyl ether extraction, in which the aluminum chloride from precipitation is extracted with isopropyl ether, if necessary; caustic purification, in which a crude alumina is produced and then purified by a modified Bayer operation; or sinter purification, in which a crude alumina is produced and then purified by a lime-soda sinter operation. For plants producing 1,000 tons of alumina a day the estimated operating costs per ton of alumina are: [Isopropyl ether extraction process $ 65.09 Gas precipitation process 89.04 Gas precipitation-isopropyl ether extraction process 119.65 Caustic purification process 73.79 Sinter purification process 80.47] The estimated fixed capital costs per annual ton for these plants on a Marshall and Stevens chemical equipment basis of 240.0 are: [Isopropyl ether extraction process $229.03 Gas precipitation process 287.16 Gas precipitation-isopropyl ether extraction process 356.59 Caustic purification process 266.48 Sinter purification process 279.13]

Jan 1, 1962

By Bin Du

In recent years, concurrent product design and process is gaining popularity and will become a norm of the industry of the future. Forging has been a critical manufacturing process for production of components with superior tensile strength, toughness and grain flow. This paper describes an expen system which is being developed for forging die design and forging process analysis in concurrent engineering environment. Rules and guidelines pertaining to forgeability are formulated and incorporated into the knowledge-base in building the system. The system is built using an object-oriented paradigm. The object-oriented approach and hierarchical rule structure paradigm are briefly discussed. Finite element analysis packages (ALPID-2D) were incorporated into the program to give the simulation result of the forging process. The system can automatically produce a competent design and recommend a set of processing parameters for a given product. The designer can modify the design according to the result of the simulation.

Jan 1, 1992

By H. R. Thresh, A. F. Crawley

THIS paper reports the results of viscosity measurements on cadmium and indium undertaken as part of a continuing program of liquid metals research at the Mines Branch, Department of Energy, Mines and Resources, Ottawa, Canada. For several years this work has continued with support from the Canadian Zinc and Lead Research Committee and the International Lead and Zinc Research Organization. In the literature, existing viscosity data for cadmium are conflicting and for indium are scarce. To achieve reliable viscosity values, further work was deemed desirable. Viscosities were measured using an absolute technique applied to an oscillating closed right cylinder of liquid metal. The apparatus, constructed in this laboratory, and the techniques involved in its use have been described in an earlier paper.&apos; In calculating viscosity coefficients from the experimental data. Roscoe&apos;s2 mathematical analysis was used. Because accurate viscosity determinations are dependent on accurate density data, and since the available data in the literature are conflicting, the densities of liquid cadmium and indium were also determined in this laboratory by a pycnometric technique. This increased the control exercised over all the variables contributing to the accuracy of viscosity measurements. For both density and viscosity determinations, cadmium and indium of 99.999 pct purity were used. These materials were obtained from Cominco Ltd. In order to suppress excessive evaporation losses and help prevent oxidation, a technique developed in measuring the viscosity of zinc&apos; was used for cadmium. This involved maintaining an atmosphere of purified hydrogen in the viscosimeter during the rela- tively long periods while the experimental temperature was changed and stabilized between individual determinations of the logarithmic decrement. Then, immediately prior to a decrement measurement. the viscosimeter was rapidly evacuated to a pressure of about 2 X 10-6 torr. On the other hand. with indium. no difficulties arise from vaporization or oxidation. In this case. therefore. the apparatus was held under a constant vacuum of about 2 x 10-6 torr. When all sources of random and systematic error have been evaluated, the technique is considered to yield data accurate within 10.5 pct. The viscosity of cadmium was measured to a maximum temperature of 451.8°C and that of indium to 346.5°C. These temperatures are. respectively. 130° and 190°C above the melting points. Two separate runs were made on indium. The results are given in Table I and, when plotted. yield the smooth curves evident in Figs. 1 and 2. Values of A and C to fit the well-known Andrade1 equation were determined by a regression analysis. The equation is: where n = coefficient of viscosity. i = specific volume. T = temperature in °K Despite its empirical nature. Andrade&apos;s equation has been shown by many workers to describe accurately the temperature dependence of viscosity. During the current research program, this equation has been found to fit the data precisely for all the metals and alloys that have been studied.5,6 The A and C&apos; values for cadmium and indium are given in Table 11. Comparing the magnitude of the present data with those of previous workers,7-10 as has been done in Fig. 1, it is evident that the results of Fisher and Phillips10 deviate markedly from the rest. With the exception of one point from Gering and Sauerwald,7 all other data agree within ±2.5 pct. However, the agreement between the present results and the work of Menz and sauerwald9 is especially good over the entire experimental temperature range. Such agreement may be expected since Menz and Sauerwald&apos;s

Jan 1, 1970

By M. S. Oudenhoven

The Bureau of Mines conducted an investigation to determine the theoretical stress distribution in the vicinity of explosively expanded rock bolt anchors independent of their bolts. Plane-strain solutions applicable to this problem were obtained by combining the field pressure with the uniform pressure that would be produced by vertically placed anchors having 2-, 3-, and 4-foot spacings. High rock stress which would be produced by an anchor was localized, as would be expected from St. Venant&apos;s effect, and increased as the field pressure decreased.

Jan 1, 1967

By Fred Leonard

This report is principally concerned with the engineering and economic feasibility of area surface coal mining systems other than draglines. This analysis evaluates shovel/ trucks, shovel/crusher/conveyors, and shovel/rail excavation and haulage systems for an assortment of geologic environments and production rates in the Powder River Basin (PRB) Shovel/trucks, front-end loaders/ trucks, and shovel/crusher/conveyors were studied in a multi-seam, dipping geologic area of the Four Corners Region. The Texas lignite engineering and economic research involved bucket-wheel excavators (BWE), BWE/backhoes, and scraper/backhoe combinations for overburden and coal excavation. The PRE truck/shovel study utilized the most recent computer simulation available in both the design and cost analyses. Detailed engineering analysis, followed by in-depth operating costs (operating and depreciation) result in a complete evaluation of each mining system. Cost comparisons of the different mining systems under similar geologic and production constraints are presented in the report to illustrate the estimated capital investment and production costs per ton of coal and bank cubic yard of overburden.

Jan 1, 1980

By J. S. Y. Wang, R. C. Trautz

A 9-meter-long drift was constructed in the unsaturated-fractured tuff at Yucca Mountain to evaluate the potential for water seeping into an underground opening. Forty seepage tests were performed by releasing a finite volume of water at a constant rate into short test intervals located in boreholes positioned above the drift. The seepage threshold flux, defined as the liquid-release flux at and below which water will not drip into the opening, was determined for 10 test intervals. The seepage data, observations, and model results indicate that a seepage threshold exists because a capillary barrier diverts water around the opening.

Jan 1, 2000

By Angela Selau Marques

A ferramenta CAE possibilita a avaliação do processo de forjamento virtualmente para otimização da produção industrial reduzindo o custo final do produto através do mínimo uso de matéria prima, juntamente com a previsão das variáveis que ocorrem durante a conformação do material no processo. Os procedimentos necessários para o forjamento de uma peça com geometria de média complexidade forjada em alumínio é apresentada. O objetivo deste trabalho é analisar experimentalmente o forjamento desta e compara-la com a simulação computacional.

Aug 8, 2018

By O. Lashkari

Manipulation of pouring temperature is an efficient way to produce different microstructural features. In order to characterize the microstructure of rheocast billets due to different superheats of 615-695 °C, the parallel plate compression method was employed. Foundry 356 Al-Si alloy with different morphologies of primary a-Al particles were tested at different initial pressures of 4,8, 11,2 KPa, The resulted strain-time graphs were further treated mathematically to calculate viscosity of SSM billets. The interrelationships of viscosity, the microstructure and primary phase flow during compression are discussed, It is shown that the dendritic primary a-Al structure has the highest viscosity number which is almost three orders of magnitude greater than those for globular morphology, The current research have, for the first time, shown the validity and reliability of "parallel plate compression viscometry" method in characterizing microstructural evolution of Rheocast SSM billets.

Jan 1, 2005

By G. R. Hopkins

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Jan 1, 1927

By M Johnson, M Horrigan

The scope of this report is to examine the aforementioned hypothesis by performing a detailed analytical comparison of a P&H electric rope shovel to an O&K diesel powered hydraulic excavator. In order to complement the integrity of the concluding results, two different size categories will be analysed in order to demonstrate that the findings can be extrapolated and applied to all the machinesÆ size classes. These two size classes are categorised by their bucket sizes and they are in the range of 43 - 58 cubic metres and 23 - 26 cubic metres. It should be noted that electric powered hydraulic excavators will not be considered in this report. In order to compare the electric and hydraulic types, the machine variants that will be analysed are commercial cost-effectiveness and operational flexibility. Although operational flexibility can be an ambiguous characteristic, a clear and thorough definition describing its exact meaning has been included. In order to simplify this study, all the data collected for this comparison have been for overburden removal, eliminating the variation that occurs with the movements of the shovel when selectively mining in the ore deposit. Thus, it ensures that all the data that is compared stems from a common origin for all the shovels. In other words the information will be compared when digging in the same material, loading into the same sized haul trucks, and when possible, with the same operators. Theoretical data received form the respective manufacturers, and actual data obtained from Mount Whaleback, was used for this comparison. This leads to the final comparison, where the operational flexibility and the cost-effectiveness are evaluated, with respect to their individual importance, ultimately influencing the final recommendation.

Jan 1, 2002

By P. C. Thurston, T. Setterfield, D. H. Watkinson

"The Maybrun copper deposit IS In a succession of pillowed basaltic flows in the Wabigoon sub-province, northwestern Ontario. The rocks have primary flow morphologies and remarkably well-preserved crystallization textures, including quench-textured plagioclase, in spite of metamorphism to the amphibolite facies. The sulphide assemblage chalcopyrite-pyrrhotite-cubanite with minor sphalerite and pyrite is primarily in interpillow spaces and is stratabound. Basaltic rocks immediately enclosing the copper sulphide minerals have an enrichment in Fe, Mg and K and depletion in Ca and Na relative to surrounding flows. The Maybrun deposit is interpreted to have formed contemporaneously with volcanism and alteration, and was subsequently metamorphosed with the enclosing basalts.IntroductionThe association o f significant base metal accumulations with mafic submarine flows in the Archean is as yet poorly documented. Such deposits, where noted, have typically been small, and are therefore commonly over looked. The Maybrun Mine, a 2.6 x 106-tonne copper deposit in pillowed basalt, has many similarities with large, well-documented volcanogenic deposits. Given the interpretation of the Maybrun Mine to be volcanogenic in origin, there is n o reason why similar processes could not produce large deposit s. This is an important realization in an area where Archean submarine mafic rock s are very common, but frequently are examined only superficially. As gold commonly occurs in deposits such as Maybrun, even modest-sized deposits may be economic. The basalts at Maybrun are remarkable for amphibolite-facies rocks because of their extremely well-preserved delicate volcanic textures, including quench textures.The Maybrun Mine is one kilometre south of Atikwa Lake, in the Wabigoon sub-province of the Superior structural province, 75 km southeast of Kenora, northwestern Ontario, at longitude 93°35&apos;W, latitude 49°25&apos;N (Davies, 1973). Archean metavolcanic and metasedimentary rocks and intrusions underlie the area. Goodwin (1970) concluded that the mafic and minor felsic metavolcanic rocks, as well as the overlying metasedimentary rock s, were an eastward extension of the lower cycle of the Keewatin type section for the Lake of the Woods area. He estimated that the stratigraphic thickness of Keewatin rock s in this area is about 6900 m, of which 87% is basalt. The flows contain numerous interlayered sills, predominantly of basaltic composition; they have been extensively folded, faulted, metamorphosed to amphibolite facies and intruded by numerous felsic bodies, most importantly the Atikwa Batholith."

Jan 1, 1983

By Ronald Erdmann

Today the BOF filter dusts and sludges are mainly dumped due to their zinc contents. By typically ranging from 2 to 5 % they prevent the filter dusts and sludges from beeing recycled via the blast furnace route. Based on the different discharge kinetics of Iron and zinc during the main blowing period In a bottom stirred BOF a simple and efficient system for recovery allow zinc fractions has been developed. The obtained material Is suitable for recycling without nsc of shell formation In the blast furnace. Different subsequent development steps have been performed. By starling with a very simple lime dependent model the sludge from the BOF off gas cleaning system was collected in two different sludge channel systems. This model based an the fact that most of the scrap based zinc Is discharged from the melt within the first eight to ten minutes of the BOF process. To Improve the system a spectroscope zinc sensor was Installed at the hot section of the off gas cleaning system to get more reliable informations on the actual zinc concentation of the BOF dust. By use of the system up to 50 % of the BOF sludge can be recycled.

Jan 1, 1995

By H. Fechtig, R. H. Buck, A. G. Guy

MULTIPHASE diffusion has been studied for many years in two-component systems1,2 and many of the experimental aspects are now fairly well understood.314 Although by no means all of the problems connected with the two-component case have been solved,&apos; attention has recently been directed to the more complex situation involving three components. The pioneer work of Clark and Rhines6 yielded a qualitative picture of the types of behavior that can occur, and Clark7 has suggested conventions for describing the various phenomena. Kirkaldy and co-workers8,9 have made quantitative studies in several ternary systems and have offered explanations of the occurrence of isolated and nonisolated precipitates. At present, however, there is no comprehensive theory for the variety of phenomena observed in ternary, multiphase diffusion. By analogy with several studies that have been made of multiphase diffusion in the binary Cu-Zn system,2&apos;10&apos;11 a similar exploratory study was made of Cu-Zn-Ni alloys lying along the line in the ternary diagram from the point 80 Cu-20 Ni to the zinc corner of the diagram, Fig. 1. A principal question to be answered was whether initially plane interfaces would remain plane during the course of one-dimensional diffusion. The diffusion specimens studied are described in Table I. The five separate alloys from which they were made were melted in evacuated Vycor capsules from 99.9 pct purity copper, zinc, and nickel. Since some of the alloys were too brittle to be swaged, all of the alloys were used in the cast condition. To facilitate later homogenization, the molten alloys were solidified by plunging the capsule in water. Homogenization heat treatment was done at 720°C for 20 hr. The five nominal compositions in weight percent zinc and nickel, respectively, were: 37.5, 12.5; 44.0, 11.2; 50.0, 10.0; 55.0, 9.0; 65.0, 7.0. Ln Table I the alloys are identified only by their zinc content. Sandwich-type diffusion specimens were prepared by pressure welding disk specimens, each about 3 mm high by 10 mm in diameter. Welding was done in a special threaded vise which was heated at 500°C for about an hour in an atmosphere of flowing hydrogen. A measurement of the separation of the phase interfaces was made on a polished flat on the welded specimen, and then the specimen was sealed in an evacuated capsule and given the diffusion treatment shown in Table I. The diffused specimen was sectioned longitudinally

Jan 1, 1965

By R. V. Ramani, J. M. Mutmansky, J. Qin, J. Organiscak, R. Bhaskar

"The results of a two—year research study into the relationship between quartz dust levels in host material and in respirable dust in continuous mining sections are presented in this paper. The experimental design and sampling procedures for underground data collection are outlined. The sample analysis procedures for quartz determination, the ¬analysis results and conclusions of the study are discussed.The results of the study indicate that the quartz contents of the airborne dusts are generally higher than those in the host material and bulk samples; and the quartz content increases with decreasing size of the airborne dust. The source for quartz appears to be the roof and the floor materials rather than the coal seam itself. It also appears that the material containing quartz may be breaking into a different size distribution than coal.INTRODUCTION Without doubt, the potential for permanent and severe health damage exists due to respirable dust in the work environment. The attention directed at the reduction of respirable airborne dust to levels below those specified in the law and the achievements to date in meeting these standards are but a reflection of the recognition by many parties government, industry, and labor - of this potential and the need to reduce it.The ambient dust standard in underground U.S. coal mines (2 mg/s3) has a qualifier (Code of Federal Regulations, Title 30, Part 71.101) to determine an applicable dust standard when a respirable dust sample contains more than 5% quartz. This standard is frequently referred to as the ""reduced standard."" The reasoning behind the reduced standard is the relative toxicity of the quartz dust compared to that of pure coal dust. As the quartz levels in samples increase, the applicable standards become more stringent and maintaining the workings in compliance becomes increasingly difficult.The number of underground work locations operating under the reduced standards has shown a dramatic increase since 1980 (Figure 1). For comparison purposes, there were no mining entities operating on reduced standards prior to 1977. The emergence of this problem, which affects the health and safety standards on one hand and creates severe compliance problems on the other, has been rapid."

Jan 1, 1990

By R. L. Wilcox, M. L. Fuller

Most commercial alloys undergo changes in phase composition after casting. This is a natural result of the fact that the alloys are not in a state of phase equilibrium as cast and phase changes will therefore take place, with more or less rapidity, in an attempt to attain equilibrium. The practical aspect of aging in zinc-Alloy die castings concerns the changes in physical properties and in dimensions that may accompany aging phase changes. Harmful alterations have been reduced to a minimum and zinc-alloy die castings are being produced today that are so stable with respect to dimensions and physical properties that they are entirely suitable for most practical purposes1. In the first paper2 of this series, and in this paper, aging phase changes of zinc-alloy die castings have been investigated and the possible influence of these changes on dimensional changes of the castings has been evaluated and compared with the dimensional changes actually experienced. The change of dimensions has been selected for practical comparison in these papers because the effect of phase changes on the dimensions of a casting is directly calculable from X-ray crystal-analysis data of the phase structure. The die-casting alloys considered contain, in addition to zinc, 4 per cent of aluminum, about 0.03 per cent magnesium, and from 0 to 3 per cent of copper. It was shown in the former paper that the eutectoidal decomposition of the beta aluminum-zinc phase, while intrinsically capable of causing a considerable shrinkage, can have very little effect on the observed shrinkage of die castings because it takes place within a few days of aging, whereas the observed shrinkage continues for five weeks. It was therefore concluded that the other existing phase change, namely, the segregation of secondary phase from the zinc-base solid solution, must account for the major portion of the shrinkage.

Jan 1, 1936

Due to the ongoing restructuring of the mining industry in central Europe with a continuous decline of the number of large underground mines and collieries, and a simultaneous decline of staff numbers in the remaining mines, the established mine rescue schemes are endangered to collapse. With the end of the mine rehabilitation at Wismut Uranium in 2014, the last remaining major mine rescue teams in Saxony, providing basic mine rescue services for all other mines in the region, will disappear. This will leave a large number of small mines and other underground operations without capable mine rescue support. Since none of these companies is able to set up a complete mines rescue unit on its own, new ways have to be found. Among others, a central mine rescue team for central Germany as well as the assistance by special trained professional fire fighters or mine rescue teams from abroad are discussed. Problems like location of the central rescue team, financing, communication and transport have to be solved. This paper provides an overview over the complexity of the problem as an example for other mining regions worldwide and will discuss national and cross-national strategies.

Feb 23, 2014

By M. Hermanus

1. INTRODUCTION It gives me great pleasure to extend my warmest greetings to everyone attending the 30th International Conference of Safety in Mines Research Institutes. I would also like to bid a special welcome to all of the international delegates who have travelled to Johannesburg to take part in what surely be a most rewarding session of deliberations. As you come together over next four days, you will have a wonderful opportunity to exchange ideas and information on strategies and practices for the implementation of sustainable patterns of development. The objectives of this meeting are both timely and far-reaching, as countries around the globe work towards the sustainable use of the world resources. Each of you brings a high level of expertise to these deliberations. I know that you will make the most of this opportunity to address the challenges and opportunities to highlight the most innovative and technologically efficient methods of social protection in order to ensure an increase in the quality of life, health, safety and living environment for the peoples of the Africa. Our country, although endowed with an immense and diverse array of mineral deposits, is perhaps best known in the mining industry for the fact that it is the world’s biggest producer of gold. Although South African gold production has declined over the past years and the industry faces serious problems, it is a myth that the South African industry is moribund. There is a new energy coursing through the South African producers which will ensure their powerful presence for many years to come, based not only on their domestic production but also and probably increasingly on their external operations. Africa features prominently in the latter category.

Jan 1, 2003