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By Holbrook G. Botset

Experiments performed in this laboratory on the flow of gas-liquid mixtures through unconsolidated sands have been described and discussed in an earlier paper.4 In these earlier experiments a definite relationship was found between the liquid saturation of a sand and its permeability to the liquid or gas phase. Furthermore, the nature of the sand, the permeabilities of the sands over a range between 17 and 260 darcies, appeared to have a negligible effect upon the saturation-permeability relation. Likewise experiments indicated that the viscosity of the liquid, or the substitution of an immiscible liquid for the gas phase, had only a very slight effect on the permeability-saturation relation. This conclusion has since been definitely confirmed by the experiments of M. C. Leverett3 on the flow of oil and water through unconsolidated sands. The sands used by Leverett were of very low permeability (between 6.8 and 1.04 darcies), while the oil-water viscosity ratio varied between 90 and 0.057. Since the sands that constitute petroleum reservoirs are largely consolidated, although of widely varying degrees of consolidation, it was desirable to extend the experiments on gas-liquid mixtures to consolidated sand. In the study of consolidated sands additional variables are involved, but for the initial experiments the only new variable to be introduced was the cementing material. Experimental Procedure A comparatively limited assortment of sandstones was available for the selection of the experimental material. Of these, the Nichols buff sandstone appeared to be most suitable. It gives no visual evidence of any bedding planes, it has a firm structure, permitting easy handling, and its permeability is about 0.5 darcy. Its only disadvantage is the fact that it contains an appreciable amount of ferric oxide which, for experiments involving water, will hydrate and reduce the permeability. This

Jan 1, 1940

By John A. Organiscak

The Bureau of Mines evaluated a new dust control technique for longwall personnel required to work at the tailgate end of the face. This technique utilizes a water-powered scrubber to clean a portion of the face air, which is discharged behind a brattice partition at the working area. Laboratory simulation of this system in a wind tunnel resulted in average efficiencies greater than 70 pct with system efficiency directly related to scrubber quantity. Underground evaluations indicated a similar direct relationship between scrubber quantity and system efficiency. Gravimetric measurements of respirable dust made during these underground evaluations resulted in average protection efficiencies ranging from 30.7 to 42.5 pct with increasing scrubber air quantity.

Jan 1, 1983

By R. A. Breitrick, J. N. Swinderman, J. J. Cooper, H. L. Bauer Jr.

The Robinson Mining District, near Ely, Nev., is one of the major porphyry copper districts in the world. Within the district is an eight mile long east-trending zone of altered porphyry, metamorphosed sedimentary rocks, and sulphide mineralization surrounded by Paleozoic limestone, dolomite, shale and sandstone, Tertiary volcanics, and Quaternary alluvium. Six major disseminated ore deposits have been exploited in this zone. About 20% of the district production has come from disseminated ore in metamorphosed sedimentary rocks found adjacent to altered quartz-monzonite porphyry. The following brief statements summarize some of the relations between porphyry alteration, metamor-phism, and mineralization: 1) Disseminated copper ore does not occur in unaltered porphyry or in m-metamorphosed sedimentary rocks. 2) Sedimentary rocks have been only weakly metamorphosed where intruded by unaltered porphyry. 3) Intensely metamorphosed sedimentary rocks are found only adjacent to altered porphyry. 4) Many hydrothermal minerals are common to both altered porphyry and adjacent metamorphosed sediments. 5) Disseminated ore is found in altered porphyry and adjacent metamorphosed sedimentary rocks. 6) In general, there is a direct correlation between grade of ore in porphyry and copper content in the adjacent rocks. 7) Chemical changes in the altered porphyry and metamorphosed rocks appear to be related. The foregoing relations support a hypothesis that the porphyry alteration, the metamorphism of the sedimentary rocks, and the ore deposition were all part of a continuous hydrothermal process which probably closely attended the porphyry intrusion. The Robinson Mining District, most often referred to as the Ruth or Ely District, is located in eastern Nev. and is one of the major porphyry copper districts of the world. Production from 1908 through 1962 was nearly 250 million tons of ore averaging a little over one percent copper with a total metal value of nearly one billion dollars. The ore has been produced from six major disseminated-type deposits with the Liberty Pit deposit accounting for 70% of the total district production. Less than one million tons of base metal and gold ores have been produced from the replacement-type deposits of the district. Approximately 20% of the district production has come from underground mining operations; the pit ore has been mined with shovels and removed by train haulage, truck-train haulage combinations, truck haulage, and presently by a combination truck-skip system. Many of the ore deposits formerly worked by underground methods have been and are being exploited by open pit methods. (See Fig. I.) Two co.'s have accounted for virtually the entire production from the district. In 1958 Kennecott Copper Corp. acquired the district assets of Consolidated Coppermines Corp. and is now the sole ore producer in the district. Present operations are confined to the Liberty Pit where 22,500 tons of ore averaging a little less than 0.8% copper is mined per day. Cutoff grade is 0.4% copper, and the stripping ratio is three to one. The ore is hauled by rail 23 miles to the McGill Reduction Plant where it is concentrated to about 20% copper. Molybdenite is recovered as a by-product in the mill. The copper concentrates are smelted in McGill, and the blister copper is shipped for refining to Balt. where gold, silver, platinum and palladium are recovered. The Robinson Mining District has been well known as a porphyry copper district for the past fifty years, but many geologists are unaware of the fact that a large portion of the production has come from disseminated ore found in metamorphosed sedimentary rocks. The scope of this paper describes the occurrences of disseminated ore in the various metamorphosed sedimentary rocks, and presents evidence for the hypothesis that these ores are genetically, spacially, and coevally related to the disseminated ore in the porphyry rocks. Publication of this paper was granted by the management of Kennecott Copper Corp. A. H. James suggested and encouraged the writing of the manuscript. Special mineralogical and spectrographic analyses were performed by the Kennecott Research Center. The deposits of the district have been studied by many geologists since the turn of the century, and

Jan 1, 1964

By Samuel S. Wyer

The following description of methods for conducting gas-producer tests is probably the first attempt to give the subject an analytical, thorough and comprehensive treatment. In some cases where tests have been made, the methods have been so unsystematic and ambiguous that it has been impossible to secure comparable results. To eliminate this difficulty, the following provisional code of gas-producer tests— which has some resemblance to the code of boiler-trials of the American Society of MechanicalEngineers—has been developed. The primary object in testing a gas-producer is to determine whether the producer is working satisfactorily or, what is the same thing, to see if the efficiency is as high as it should be with the type of producer in question; and also to find out if the composition of the resulting gas is adapted to the work it has to do. In order that the test shall be of any value, it must be thorough and comprehensive, and must be conducted with skill and care. When so conducted, the test will reveal the economy of the'producer; and, by making suitable changes, the efficiency will often be increased very much. As a result of the tests made by Jenkins,' the efficiency was raised from 56.2

Jan 1, 1906

By A. S. Paschoa, A. W. Nóbrega

INTRODUCTION There are now over twenty years since the radiological characteristics of the brazilian regions of Araxá, Tapira and Barreiros, three locations adjacent to each other, in the state of Minas Gerais, Brazil, started being surveyed by investigators from the Instituto de Biofísica da Universidade Federal do Rio de Janeiro (IB/UFRJ), Pontifícia Universidade Católica do Rio de Janeiro (PUC/RJ), and New York University (NYU) (Roser and Cullen, 1958; Cullen et al, 1980). The importance of the Araxá apatite – Ca5,(P04)3(OH, F, Cl) - and pyrochlore - NaCaNB206F - for the production of large quantities of fertilizers and niobium was early recognized (Roser and Cullen, 1958). Interesting data have been gathered and published throughout the years on the contents of naturally occurring radionuclides in geologic materials, soils, grass, foods and waters of the Araxá region (Eisenbud, et al., 1964; Penna Franca, et al., 1965a, b; Roser et al., 1966; Penna Franca et al., 1970; Cullen, 1977; Penna Franca, 1977; Cullen and Paschoa, 1978; and Cullen et al., 1980). The radioactivity of the Araxá region is associated with mineral deposits of niobium rich pyrochlore and phosphate rich apatite. There are in this region mineral ores with 3 to 5% pyrochlore with 2 to 2.5% Th as Th02 and 50 to 150 ppm U308 in the matrix, while the apatite deposits contain up to 150 ppm U308 and a thorium concentration similar to that of the pyrochlore deposits (Paschoa and Palacios, 1981). As an indication of the high thorium content of the Araxá soils the 228Ra and 224Ra activity concentrations were reported to range from 10.6±0.2 to 62.4±0.7 pCi228Ra/g soil in 7 samples and 2.1±0.1 to 104±1 pCi224Ra/g soil in 19 samples (Cullen, et al., 1966). The uptake of radium isotopes by edible roots vegatables and fruits growing in the soils of the Araxá region can be illustrated by the data listed in Table I. The biological availability of natural radium isotopes in some segments of the Araxá soil allows a large variation in the 228Ra, 224Ra and 226Ra concentrations in vegetables and edible roots, as can be seen in Table I. This fact makes quite difficult a quantitative local assessment of the radiological implications of mining the Araxá mineral deposits of pyrochlore and apatite for production of niobium and phosphate fertilizers, respectively; since one cannot easily separate the naturally occurring from the technogically enhanced radionuclide contents of foods. The position of the city of Araxá inside the contour of the state of Minas Gerais appears in the upper part of Figure 1, which shows the outlined map of Brazil with the positions of the cities Brasilia and Rio de Janeiro also indicated. The lower part of Figure 1 is a representation of the Araxá region in an expanded scale, which indicates the locations of the pyrochlore and apatite deposits in relation to the city of Araxá, as well as the nearby hydrographic basins. The distance between the city of Araxá and the pyrochlore deposit is about 8 km, and between the pyrochlore and apatite deposits is 4 km. This paper deals tentatively with the radiological implications of the industrial operations taking place in the Araxá region for the exploration of the pyrochlore and apatite deposits. However, one must bear in mind, firstly, that the radiological implications of these industrial activities are by far too complex to be covered adequately by the limited amount of data to be presented in this paper, and secondly, that such implications cannot be considered of local character only. INDUSTRIAL OPERATIONS The commercial exploration of the Araxá deposits of pyrochlore and apatite started only few years ago, motivated by the increasing demand of niobium and phosphate fertilizers in Brazil and the world. As a consequence of the industrial operations in Araxá, a redistribution of the uranium, thorium, and radium originally present in the local deposits of pyrochlore and apatite started occurring in the seventies, with possible radiological implications for the Araxá region and its immediate surroundings, not to mention the destinations of the end products of such industrial operations. A literature review on the radioactivity associated with the extration industries of selected minerals was made by the USEPA (Bliss, 1978). The low level radioactive wastes of the industries for copper ore mining and rare metals processing have been object of particular attention (Fitzgerald, Jr., 1976; Eng, et al., 1979), but the short and long term implications of the radioactivity associated with the niobium industry were also subjects of concern (Knight and Makepeace, 1978). Recently, high 232Th and 226Ra concentrations in samples from the tin mining industry in West Malaysia were reported (Hu et al., 1981). A great deal of attention has been dedicated to the implications of the redistribution of radionuclides originally present in the mineral ores used by the phosphate fertilizer industry (Moore, 1967; Menzel, 1968; Spalding and Sackett, 1972; Eisenbud, 1973; Guimond and Windham, 1975; Guimond, 1976; Roessler,

Jan 1, 1981

By Filippos Patsiogiannis

Laboratory size (5 kg) aluminum killed low carbon steel melts were desulfurized with synthetic fluxes in zirconia crucibles. The sulfur, oxygen, aluminum, silicon, and manganese contents in the melt were determined as a function of refining time and temperature. With a good argon shield and synthetic flux cover, melt reoxidation was not observed. Sulfur removal followed first order reaction kinetics. The effectiveness of calcia saturated calcium-aluminate (12CaO.7Al2O3) based fluxes in desulfurizing the steel melts was evaluated. The effects of initial sulfur level of the melt, weight of the flux (slag), and additions of tellurium, fluorspar, and barium oxide to the melt on the kinetics of desulfurization were also studied.

Jan 1, 1993

By A E. Annels, M D. Raine, I M. Platten

Lode-gold systems are often characterised by a high to extreme nugget effect (>50 per cent), and the presence of coarse gold particles (>100 ¦m in size). They rank amongst the most difficult of ore deposits types, in terms of producing an accurate and precise resource estimate. Their effective sampling is generally difficult because of the relatively low concentrations involved and erratic nature of the gold particles. Grade continuity is usually less consistent than gross geological continuity, and is typified by the localisation of grades within discrete oreshoots. In most cases drilling, particularly diamond drilling is an effective measure of global geological continuity, whereas grade can only be reliably resolved from underground development. Depending upon drill density and geology, it is unlikely that anything above an Inferred Mineral Resource can be estimated from surface drilling alone. Underground development, in-fill drilling and, potentially, bulk sampling or trial mining will be required to delineate Indicated and Measured Mineral Resources and subsequent Ore Reserves. Grade estimation will have to account for highly skewed and often multi-modal populations, extreme values, a high nugget effect and low geostatistical ranges. A clear geological model that honours both geological and grade continuity must drive the resource estimation process.

Jan 1, 2003

By W. Everett Smith

Factors that have influenced mineralization in the Valley and Ridge and Piedmont provinces in Alabama are not clearly understood. Lithology and structure are recognizable factors in the Valley and Ridge province, where barite, lead, and zinc sulfides occur in structurally complex areas of Cambrian and Ordiovician carbonate rocks. Metal mineralization in the Piedmont province indicates a complex relationship with factors such as favorable host rock, proximity to intrusive or high-grade metamorphic rocks, several metamorphic events and separate or related structural events. Lineaments, as used herein, refer to naturally occurring linear features consisting of topographic, vegetative or soil tonal alignments that are at least partially continuous for distances greater than a mile (Lattman, 1958). Lineaments in Alabama were first recognized by J. G. Newton in 1970, using Apollo 9 series photographs. Subsequent studies delineated the features (Powell and others, 1970) and suggested relationships to structural and hydrologic factors. More recent work has explored relationships to mineralization, environmental geology and the tectonic framework of the Appalachians (Drahovzal and Copeland, 1970; Drahovzal and Neathery, in press). The lineaments recognizable on Apollo 9 photography probably represent fractures, some of which may reflect geofractures that bound major basement blocks. The lineaments defined in Alabama range from about 4 miles to nearly 200 miles in length. Most of the lineaments are straight, but some are arcuate; some appear to terminate at the intersections with other lineaments but most cross each other with no offset. Some lineaments pass through areas of structural disruption such as terminations, offsets and changes in structural style, but others show no such relationships. Most of the lineaments appear to cross topographic features with little or no obvious disruption. Orientation analyses of the lineaments divide them into three directional groupings

Jan 1, 1972

By S. G. Cupschalk, F. A. Dahlman, J. J. Wert

Studies have been undertaken to determine the indicidual effects of particle size, degree of long-range ovder, antiphase domain size, and root mean square stran on the microhardness and yield strength of ordered alloys. Dnta have been analyzed for Cu3Pt initzally ordered to a value of 0.82 and after deformations of 1 and 6 pct. It was observed that deformation fleatly reduced the degree of long-range order. Furtherrnore, wztkin this range of relatively small deforntntlons, the average particle size changed very little while the antiphase domain size was greatly reduced. Smultaneosly, the mcrohardness changed by a factor of two durzng the deforrtation process. PREVIOUS studies have reported some of the effects of cold work on the broadening of X-ray diffraction peaks. These investigations were performed on powder and wire samples representing both ordered and disordered states; i.e., the specimens were initially studied in a severly cold-worked condition. By comparing the difference in line shape between the annealed and cold-worked peaks, fundamental information was obtained concerning particle size, strain distribution in different crystallographic directions, degree of long-range order, and change in antiphase domain size. Considerable theoretical work has been done concerning the analysis of diffraction data obtained from cold-worked metals. Stokes' expressed the change in diffraction profiles in terms of Fourier coefficients. Much of the work in this area has been summarized by warren2 in an extensive review article concerning the analysis of plastic deformation by X-ray diffraction. Cohen and Bever3 applied these techniques in studying the effects of cold work on alloy systems exhibiting long-range order. They utilized the Fourier coefficients of fundamental peaks in conjunction with those of the superlattice peaks to determine the change in antiphase domain size. Little work of this nature has been reported for ordered systems that have undergone small degrees of plastic deformation. The purpose of this investiga-tion was to determine the effects of small deformations in such a material with respect to particle size, strain distribution in various crystallographic directions, antiphase domain size, degree of long-range order, and hardness. EXPERIMENTAL PROCEDURE CusPt was used for the initial investigation since the order-disorder transformation takes place with- out a change in crystal structure. The transformation is readily detectable via X-ray diffraction techniques due to the large difference in the scattering factors of copper and platinum. Additionally, the alloy is relatively low melting (approximately 1300°C) and is easily deformable in both the ordered and disordered states. 1) Specimen Preparation and Cold Working. A 100-g, 12-in. diam., cylindrical specimen of Cu3Pt was prepared by melting and casting 99.99 pct pure Cu and Pt i.n vacuo. Prior to any mechanical working, the material was homogenized in a vacuum for 60 hr at 100O0C, and surface defects were removed by machining to a depth of approximately 116 of an in. The material was then cold-rolled, with an intermediate anneal, into a strip approximately 12 in. wide by 14 in. thick. Straightening and flattening removed another 0.025 in. from the thickness. After a recrystallization treatment at 750°C for 30 min, the specimen was slow-cooled from 55OoC, at the rate of 6°C per hr, down to 150°C to induce superlattice formation. This treatment yielded an ASTM grain size of 7 and a degree of long-range order equal to 0.83 0.06. After obtaining X-ray and Knoop hardness data, the sample was cold-rolled approximately 0.75 pct in one pass through a hand-operated jewelers' mill. X-ray and hardness data were again obtained and the specimen was reduced an additional 5.41 pct in a single pass through the mill. 2) X-Ray Measurements. The specimen was examined in the ordered condition and after the two degrees of cold working previously mentioned using a General Electric XRD-5 unit equipped with a spectrometer and scintillation counter. Using Mo-Ka radiation with a zirconium filter, six orders of the 100 reflection were obtained. It was anticipated that point counting would be necessary for an accurate determination of the low-intensity peaks and tails: however, it was demonstrated that, by using a scanning speed of 0.2 deg per min and the appropriate time constant, the recorded data were sufficiently accurate. Thus, for ease of experimental procedure, all peaks were recorded on chart paper. Specimen position in the holder was considered to be insignificant after making a series of measurements of the same peak area in different positions with respect to the beam. Since peak overlapping did occur at high values of 20, it was necessary to separate the peaks graphically prior to analyzing the data in order to minimize this source of error. The peak tails were also carefully drawn to obtain the best possible data. Fourier coefficients of the line profiles were calculated on an IBM 7072 computer, and graphical meth-ods2j3 were employed in analyzing the results. For this type of calculation, in which the line profile is represented by intensities taken at set intervals, the intervals selected must be sufficiently small to give an accurate representation of the line profile. It was decided that for 20 = 0.02 deg the line profiles were

Jan 1, 1967

By L. B. Pankratz

Thermodynamic data on the halides were reviewed, evaluated, and compiled at the Bureau of Mines Albany Research Center. Values for Cp°, S°, H-H°298, -(G°-H°298)/T, ?Hf°, ?Gf°, and log Kf are given in tabular form. CP°, H-H°298, ?Hf°, and AGf° are also expressed algebraically.

Jan 1, 1984

By V. A. Marple, K. L. Rubow, S. M. Behm

"An eight-stage cascade impactor, with cut-sizes ranging from 0.056 to 18 um at a flow rate of 30 L/min, has been developed, calibrated, and tested in field programs. This impactor, called a microorifice uniform deposit impactor, has several features not normally found in cascade impactors. Ultrafine particles as small as 0.056 um are collected while keeping the pressure drop moderate by utilizing multiple nozzles (up to 2000) as small as 52 um in diameter. At each stage the collected particles are deposited uniformly over the entire impaction plate by rotating the impaction plate relative to the nozzles and by the correct radial placement of the nozzles. The particle cutoff characteristics (collection efficiency curves) of each stage and inter-stage losses were determined by means of monodisperse aerosols. The cutoff characteristics were found to be sharp and similar for all stages.Inertial impactors are widely used for the size-selective collection of aerosol particles. One reason for their wide usage is that the principle of operation is simple: a jet of particle-laden air is directed at a flat impaction plate. Large particles are collected on the plate while smaller particles follow the airflow out of the impaction region and are not collected. The division between the size of particles collected and those that are not is quite sharp. Secondly, the particles in an impactor are classified by their aerodynamic diameter (an important size parameter in many fields of study, including those related to respirable particle health effects). Thirdly, it is easy to collect particles in discrete size ranges by passing the aerosol through a number of stages (one stage consisting of a nozzle and impaction plae) in series, with each subsequent stage collecting particles smaller than the one before it. This is known as a cascade impactor. Finally, impactors can classify particles over a wide range of particle sizes: as low as 0.005 um (Fernandez de la Mora et al., 1990) and as large as approximately 50 um (Vanderpool et al., 1987).This paper describes a general purpose cascade impactor that has been developed in our laboratory and used in a variety of studies including visibility studies (McMurry et al., 1986; McMurry and Zhang, 1989), underground mine studies (Marple et al., 1986; Rubow and Marple, 1988; Rubow et al., 1988), and general atmospheric pollution studies (Macias et al., 1981; Dzubay et al., 1984). The impactor, called a microorifice uniform deposit impactor (MOUDI model 100, MSP Corp., Minneapolis, Minn.), is the integration of two earlier impactor de¬velopments: the microorifice impactor (M01) (Kuhlmey et al., 1981) and the uniform deposit impactor (UDI) (Marple et al., 1981).The MOUDI has several features normally not found in other cascade impactors. These include collection of particles as small as 0.056 um in aerodynamic diameter with a moderate pressure drop, uniform particle collection on the impaction plates, inter-changeable impaction plates to allow for the plates to be easily and quickly changed in the field, and covers for these substrates to provide a means for safe storage and/or transport of the collected particles to the laboratory for analysis."

Mar 1, 1992

By G. R. Erdman

The industrial mineral filler plant of the Gouverneur Tale Company is equipped with a good dust collection system installed long before the recent popularization of environmental pollution. Credit for this fact is due to the foresight of Mr. R. S. McClellan, Project Manager and subsequent Vice President and General Manager of Gouverneur Talc, who recently retired as Vice President Engineering of the parent organization, the R. T. Vanderbilt Company. Also instrumental in the early stages of plant operation and the solution of start-up problems was J. A. Gustin who is now an engineering consultant located in Martinsville, Va. Credit is most certainly due to the late R. T. Vanderbilt, the company's founder, who favored and approved the investment in the necessary facilities that were far ahead of all competitors in the industry at that time.

Jan 1, 1972

The co-operation of the members of the Institute is earnestly sought by the Committee on Nominations, recently appointed by the Board of Directors, in its work of formulating a ticket for officers and places falling vacant in the Board of Directors in February, 1916. The Committee must present the official ticket of nominations to the Board of Directors at its October meeting. Members are, therefore, urged to send promptly their nominations for officers and Directors in order that the Committee may have an opportunity to give them full consideration. The officers to be elected at the annual meeting in February, 1916, are: One officer, known as Director and President. Two officers, known as Director and Vice-President. Five officers, known as Director. The officers of the Institute whose terms expire are as follows: President, William L. Saunders (not eligible for re-election). Past President, Charles F. Rand. Vice-Presidents, Thomas H. Leggett, District 0; Fred W. Denton, District 4.

Jan 9, 1915

By F. W. Brown, F. C. Gibson

"INTRODUCTION There is urgent need for a satisfactory permissible multiple-shot blasting unit capable of firing 10 detonators in series and safe for use in underground mining where a. gas-ignition hazard may exist.. As there is at present no entirely satisfactory permissible unit of either the battery or generator type, tile described capacitor-battery type has been developed. Consideration of the Bureau of Nines approval schedule pertaining to the generator and magne to-type units and of the electrical characteristics of the unit described in this report indicate that this unit should meet Bureau of Mines permissible requirements.This report gives a detailed description of the design and operation and results of tests to determine safety of operation in gassy atmospheres.DESIGN AND OPERATION OF UNITOperation of the vibrator-type multiple-shot blasting unit is based upon utilization of the discharge energy from a capacitor charged to a given. voltage and having capacitance adequate to store enough energy to initiate 10 detonators in series. The primary source of energy is a 4-volt cap lamp battery such as is carried for illumination on the person of underground workers in nearly all mines. As this battery is already available and is recharged daily it is considered to be a reliable and convenient source of energy for a blasting unit. Figure 1 is a schematic diagram of the circuit for an improved unit, and figures 2 and 3 are views of the experimental unit. The battery potential is applied through a radio-type synchronous vibrator (8) to an 8-volt center-tapped primary of a small transformer (9) having a high-voltage center-tapped secondary. The vibrator introduces an alternating low-voltage potential into the primary and mechanically produces full-wave, rectified, pulsating, direct current from the secondary. A buffing condenser (11) across the secondary gives the proper wave form for long vibrator life: a resistor (12) its in series with this condenser across the total secondary to protect the transformer in case of• failure .of this capacitor. A voltage divider (10) with an adjustable slider permits accurate adjustment of the potential applied to the high-capacity firing condenser (5)."

Oct 1, 1947

Discussion of the paper of MANUEL EISSLER, presented at the New York meeting, February, 1915, and printed in Bulletin. No. 9.5, November, 1914, pp. 3661 to 2703. J. W. RICHARDS, So. Bethlehem, Pa.-I do not see in the paper a description of the Mabuki hearth as used for ore smelting. I noticed it described for concentrating matte, but I believe the older Japanese process was to use it for-smelting directly, by a pyritic smelting and Bessemerizing all in one operation, in the same simple hearth apparatus. There is a monograph published in German, on Copper-Ore Smelting in the Mabuki Hearth. At Ashio the practice of injecting bituminous coal at the, tuyères is noteworthy. It is very interesting to see two men load little cartridges on the end. of an iron rod with bituminous coal, and push them into the furnace tuyères, and with a piston inject 2 or 3 lb.. of bituminous

Jan 5, 1915

By Eric Gilmore, Ron Tudor, Gregory E. Korbin, Bill McCormick, Brad Bush

INTRODUCTION Las Vegas has recently been termed the “Construction Capital of the Country”. It has also been acknowledged as the fastest growing city in the country for several years running. The rapid growth improves the economic picture of the region but it also imparts unusual demands on the area’s infrastructure. In 1994 the Southern Nevada Water Authority (SNWA)was working on a master plan to address the rapid growth. A long range analysis revealed the need for additional water treatment capacity and delivery systems. Short term projections showed that the current system would reach capacity in the summer of 1997 with the possibility of demand exceeding the supply. The River Mountains Tunnel #2 is part of a $150M scheme to quickly upgrade the system to meet the short term demand, improve the overall system operation and allow for a smooth transition into the larger additions being planned for the future. The SNWA selected Carollo/Black & Veatch (CBV) to provide detailed design and construction management for the upgrades. The River Mountains Contracts consisted of five separate contracts broken out separately to stream line a very aggressive (just 34 months) design and construction schedule. Necessary work included four miles of excavated and lined tunnel, connections from existing pipelines to and from the new tunnel including large diameter (to 3.66m(144 in)) valves, a 18 927cu m (5 million gal) regulating reservoir, a surge tank and a 170 343cu m (45 million gal) reservoir to add additional storage to the system. Notice to Proceed was given to Kajima Engineering and Construction (Kajima) on May22, 1995 for the construction of the River Mountains Tunnel #2. The design called for a tunnel to be driven 6070m (19 915ft) in rock and lined to a finished diameter of 3.71m (12.17ft).Excavation began on December 14, 1995 and holed through on April 30, 1996. Lining began on June 25, 1996 and a notice of Substantial Completion was issued on December 13,1996. This paper describes the measures taken to complete the tunnel in 18 months from Notice to Proceed to Substantial Completion. THE RIVER MOUNTAINS SITE The River Mountains are a low range of rugged mountains separating the Las Vegas Valley from its main supply of water, the Colorado River at Lake Mead. They are volcanic in origin and the harsh desert environment has left them as expanses of exposed bedrock rising 305m (1000ft) above the valley with little or no vegetation. An existing 3.05m (10ft)

Jan 1, 1997

By G. A. Chadwick, D. Jaffrey

The morpho1ogies and orientation relationships of the phases in the Sn-Zn and A1-A13Ni eutectic systems were examined by electron microscopy and X-ray diffraction techniques. In each alloy the "transition" from the lamellar to the fibrous morphology was found to be one of scale, not of type. The minor phase in both systems exhibited certain well developed facets which were not affected by changes in the ingot solidification rate. The crystallographic relationships displayed by the pairs of phases in both systems were also insensitive to the growth rate. In the Sn-Zn alloy, the unique relationship of: growth direction - II [1201 Sn - II [01101 Zn and ribbon interface plane 11 (101) Sn 11 (7012) Zn was determined. The Al-Al3Ni alloy phases did not possess any particular orientation relationship, though the Al3Ni phase invariably grew in the [010] direction and exhibited the same set of facet planes. These results are discussed in relation to current eutectic growth theories and explanations of the "lamellar to fibrous transition". THE lamellar to fibrous transition that occurs in many eutectic alloys has been the subject of considerable speculation and experimental study. In some alloys it can be induced solely by an increase in the solidification rate,'-3 whereas in others the transition supposedly occurs only if the lamellae are forced to grow out of the overall ingot growth direction.4-6 he cause of this latter type of transition has been attributed to deviations of the lamellae from their low energy habit planes;4'5'7 fibers are produced because the sustaining force for lamellar growth (a low energy boundary) is destroyed. Implicit in these explanations is the assumption that fibers are circular in cross-section and completely lacking in low energy inter-phase interfaces. The "natural" growth rate dependent transition has been studied less thoroughly although Tiller8 has attempted a theoretical explanation of it. Tiller's arguments are not completely satisfactory9 but his suggestion that the relative undercoolings of the solid/liquid interface for lamellar and fibrous morphologies are growth rate dependent cannot be totally discounted; it is possible, for instance, that the relative interfacial undercoolings could alter and produce the observed morphology change if the orientation relationships between the phases and the associated interphase bound- ary energies were sensitive to growth rate. Salkind et al." have reported finding a change in the orientation relationships in the A1-A13Ni system accompanying the lamellar to fibrous transition, but contradictory evidence has also been reported for this3'" and another system,12 so the position remains unclear. In an attempt to clarify matters a study was made of the "lamellar to fibrous" transition in the Sn-Zn and A1-A13Ni eutectic systems; the morphologies of these two selected systems are quite similar when viewed by optical microscopy. In the present research the morphologies and morphology changes were investigated by electron microscopy. The orientation relationships existing between the eutectic phases were also determined for both morphologies in both eutectic systems. EXPERIMENTAL PROCEDURE The materials and method of alloy preparation and ingot solidification for the Sn-Zn system have been reported previously.2 In this investigation nine horizontally grown ingots of the highest purity (99.9997 pct) were used. The temperature gradient in the melt was not intentionally varied and was approximately 10°C per cm. Seven growth rates between 1.3 cm per hr and 20 cm per hr were imposed. The A1-A13Ni alloys were prepared from "Spec. Pure" nickel and 99.995 pct aluminum by melting the components in an open alumina crucible and casting the melt into the cold graphite mold. Six ingots of the Al-Al3Ni alloy were unidirectionally solidified at growth rates from 1 cm per hr to 12 cm per hr under high purity argon. A typical ingot was 20 cm long, 1 cm wide, and 0.75 cm to 1.5 cm thick. Samples taken from the bars at positions 12 cm from the nucleation end were examined by conventional orthogonal-section metallo-graphic techniques. When required, samples were mounted for X-ray diffraction analysis using the Laue back-reflection technique with a finely focussed X-ray source. The surfaces of the A1-A13Ni specimens were prepared by mechanically polishing them down to the 1 µ diamond pad stage followed by an electropolish in 80/20 methanol/perchloric acid solution at 0°C and 20 to 30 v. The Sn-Zn specimens were repeatedly polished on an alumina pad and etched in hot dilute (2 pct) nitric acid until the diffraction spots were found to be sharp. Thin films of the alloys were prepared for observation in an electron microscope by spark machining thin discs (0.03 to 0.04 in. thick) from longitudinal and lateral sections of the bars and elec-trolytically thinning them via a jet polishing technique. For the A1-A13Ni eutectic alloy, an 80/20 mixture of ethanol/perchloric acid at 40 v and 20°C was found to be satisfactory. A solution of 70/20/10 methanol/perchloric acid/butylcellosolve at 25 v and 20°C was used on the Sn-Zn alloy. For the former alloy the jet nozzles (cathodes) and the disc clamps were of aluminum;

Jan 1, 1970

By Robert L. Montgomery

Heats of solution of samarium (III) oxide and chloride in hydrochloric acid and of samarium (III) oxide, sulfate, and hydrated sulfate in sulfuric acid were measured. The heats of solution of this hygroscopic oxide are larger than those from the literature, probably because of more complete removal of water in the present study. From the literature value for the heat of combustion of samarium, the heats of formation of samarium (III) chloride and sulfate are -244.18 ± 0.41 and -928.5 ± 1.6 kcal./mole, respectively. The heat of hydration of the sulfate is -34.7 ± 1.0 kcal./mole. The heats of formation of other samarium com-pounds have been recalculated, using the new data.

Jan 1, 1959

By Morgan M. Sears, Gamal Rashed, Jim Winfield, Brent Slaker

"Over the past decade, ground falls have resulted in five fatalities, representing over 40% of all fatalities occurring in underground stone mines in the United States. In conjunction with recent high-profile pillar collapses, the need for further ground control research in the nation’s stone mines is evident. Ground conditions are growing more difficult. Therefore, this research is focused on deep cover, steeply dipping, and multi-level underground nonmetal mines. The objective of this paper is to introduce a geomechanical study of pillar development in a steeply dipping limestone deposit. To accomplish this, a numerical model was developed using input from modified laboratory test data and in situ stress measurements provided by the mine to simulate the development of a pillar under these conditions. The model was then verified against field observations and stress mapping. The calibrated model was then used to calculate the estimated stresses in the pillar and immediate roof as development progresses around an instrumented pillar.INTRODUCTIONGround falls represent a significant hazard in the nation’s underground stone mines. In response to recent large-scale pillar collapses, as well as stakeholder interactions, researchers from the National Institute for Occupational Safety and Health (NIOSH) are currently conducting detailed investigations into the complex loading conditions at mines operating in challenging operational environments. These include deep-cover, steeply dipping, and multi-level mines where there is the potential for an increased risk of ground failure. The Pleasant Gap Mine, shown in Figure 1, operates in the Valentine Formation, which is typically light grey, extremely fine-grained limestone, and approximately 21.3 m (70 ft.) thick. The Centre Hall Formation makes up the immediate and main roof members and is approximately 9.1 m (30 ft.) thick, consisting of medium-dark-gray limestone (Murphy et al., 2018). Situated in a syncline, the top of the Valentine Formation dips at approximately 19° with a strike of approximately N54E in the area of interest (see Figure 2)."

Jan 1, 2018

By Scott Stebbins

Cost estimating and economic evaluation software provide evaluators with the ability to predict the profit potentials associated with mine design alternatives even during project exploration and prefeasibility. Examining a multitude of development alternatives early on serves to identify aspects critical to profitability and to increase the reliability of economic projections. A case history illustrates how Sherpa Cost Estimating Software, when used in conjunction with Apex Software for Economic Evaluation, significantly enhances an evaluator's ability to examine design alternatives in a timely and reliable manner. The costs and economic impacts associated with various access routes, production rates, equipment mixes, and stoping methods are projected.

Jan 1, 2002