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By Alfredo Valdivia, Jesus Schabib, Vojtech Gall, William Cao, Curt Cicileo, Andrew J. Thompson

"The East Side Access Project (ESA) involves the construction of geometrically complex underground structures including a large number of caverns and bifurcations. Initially conceived as dual lined structures with either traditional concrete or shotcrete final linings (SFL), construction economy, advances in concrete placement technology and scheduling among others led to a wide use of what is referred to as freeform or pneumatically applied concrete (PAC) for the construction of tunnel final linings. PAC is a method of applying concrete without using formwork, where a wet mix concrete is pneumatically installed to encase reinforcement to full lining thickness. PAC has been widely adopted at ESA well beyond initial expectations. The paper addresses the design and construction aspects of the PAC method and contrasts it to traditional SFL lining placement. The experience made provides guidance for future PAC and SFL applications. THE EAST SIDE ACCESS PROJECT AND USE OF FREEFORM CONCRETE The Long Island Rail Road (LIRR) currently transports commuters from Long Island into Manhattan, terminating at the already congested Penn Station on the west side of Manhattan. Once completed, the ESA Project will provide LIRR commuters direct access to the east side of Manhattan underneath Grand Central Terminal. The ESA Project will help alleviate the congestion at Penn Station, which currently accommodates New Jersey Transit, Amtrak, and LIRR lines; reduce travel time for LIRR passengers traveling to the east side of Manhattan and facilitate connections to the New York City Transit (NYCT) Subway System and Metro North Rail Road. The construction includes mining and lining of new tunnels and facilities under Manhattan and Queens. The tunnels run from Queen’s Sunny Side Yard through the existing 63rd St. Tunnel, underneath Manhattan’s Park Avenue until termination at 37th Street. Differing types of tunneling methods and final lining systems are being used depending on the ground conditions, geometry and size of the excavation, site constraints and functional requirements. Mining of the Queens segment of the ESA Project involved soft ground tunneling by pressurized face tunnel boring machines, cut and cover construction, and conventional tunneling. The Manhattan segment of the ESA Project involves mining in hard rock by tunnel boring machines, drill and blast, and road header."

Jan 1, 2016

JOHN.B. HASTINGS, Los Angeles, Cal. (written discussion).-This paper reminds me that when I had an option on a Nevada mine, where the only orebodies assayed $4 gold, I went to San Francisco to learn the cost of putting broken ore in a 25-ft, vein on the mine cars, and sought Mr. Alfred Wartenweiler, who said "There is not a mine in California that can tell what it costs to move ore in the stopes." When building small mills in the mountains, and with only 30 or 40 employees, by entering in a log at night the work performed by each man, I have been able to plot the costs with the accuracy shown in this paper, and very good discipline it is. Cost of new construction and repairs is carefully kept by most companies, and is compiled after completion; probably the outlay of labor and material in pieces of work sufficiently important to call for blueprints is estimated beforehand, but numberless odd jobs of construction and repairs are so itemized. . Might it not be worth while, at a large plant, to have these smaller daily tasks described in advance in a central repair office, and then let inspectors look over the job, report time and material needed, and enter it in sufficient detail in proper ledgers, the men then being sent to accomplish it, and reporting when finished? The forecasts would soon be made quickly and correctly and would give the head mechanic, carpenter, and electrician easy supervision of their men, and the results could be seen at a glance by the managers.

Jan 4, 1918

By W. B. Dingle

"IntroductionMANY PAPERS presented on developments in the Canadian Petroleum Industry •during the past few years have commenced with this general sentence: ""The past year has been a record •one for the oil industry in Canada, with new records being set in nearly all phases •of exploration and development ,activity"". This sentence applies equally well to 1951. It is not possible to outline all the details of the broken records in exploration, development, and production but general comparisons can be made. There are several significant developments that have stolen the spotlight during 1951, some of which were foreseen in 1950 and some which were not. Among the high-lights were the following:(1) The greatly •expanded activity in the search for gas, which was touched off by the new Alberta regulations covering gas leases and reservations.(2) The discovery of commercial oil production in the Williston basin of North Dakota and Manitoba, which will have far reaching effects on Canadian oil.(3) The greatly increased activity in northern Alberta, northwestern British Columbia, the southern Northwest Territories, Saskatchewan, and Manitoba.(4) The new discoveries in the general central Alberta area.(5) The granting •of a permit for an oil pipeline to the Pacific coast.(6) The arrival of Western Canadian crude in central Ontario.(7) The number of new refineries completed, commenced, or proposed.(8) The present •and proposed expansion in the petrochemical industry.Most of the remarks made on various exploration and development •activities will refer to Western Canada operations, primarily because the greatest •activity and the most significant developments have been there. Eastern Canada exploration and development operations were at a slightly higher level than in 1950."

Jan 1, 1952

By AIME AIME

THE Charleston Section of the A. I. M. E. held a joint meeting with the National Coal Association and the American Society of Mechanical Engineers on May 6 and 7, at which 94 members and guests were registered. Mechanical operation of coal mines was the subject discussed. First on the program was a paper entitled "Rock Dusting in the Coal Mines of West Virginia," by R. M. Lambie, chief of the Department of Mines, and Gordon MacVean. It appears in full in the current issue of MINING AND METALLURGY, p. 290. J. E. Jones of the Old Ben Coal Corp. opened this discussion by describing the method of rock dusting employed in the mines of that company, giving many interesting details, incidentally referring to the use of rock dust in fighting mine fires. He described one case where a number of troughs was brought to within 150 ft. of the fire, and rock dust had been thrown in its direction. After each trough had been thrown the party advanced a few feet, where another trough was discharged. About 10 ft. were gained on each advance, until the party found they had advanced completely over the fire.

Jan 1, 1926

By S. Cossio, J. L. Noyola, R. Espinosa

"Minera Penmont’s La Herradura is a joint venture between Industrias Peñoles, S.A. de C.V. and Newmont Mining Corporation. The mine is located in the northern Mexican state of Sonora. La Herradura consists of an open pit mine with a two-stage crushing plant and heap leaching facility. Gold is recovered from the pregnant solution using the Merrill-Crowe process; production began in July 1998. La Herradura produces about 130 000 oz gold per year and its treatment capacity is approximately 22 000 t/d. Ore mineralization occurs in a shear zone with quartz and native gold. Gold distribution is quite heterogeneous due to coarse visible gold, which in some cases ranges from 100 to 600 microns.Sampling and assaying protocols were established during exploration and prior to start-up of operations, based on nomographs developed from early heterogeneity tests. However, as the coarse gold problem became noticeable, it was necessary to develop new sampling protocols to have an acceptable relative standard deviation to control the fundamental error within ± 15%.An experimental program was developed and conducted on a selected ore block consisting of 195 blastholes; regular ore grade control procedures were applied to both sets of data to evaluate the difference in results between the protocol established prior to start-up of operations (existing) and the new protocol (leaching). In the existing protocol, sub-sampling is done through riffle splitters, and coning and quartering. Fire assaying was used to estimate the gold content on a 50 g sample. In the leaching protocol, a 12 000 g sample of bottle-rolled cyanide was leached, and the leach residue was assayed on a 50 g sample using fire assaying, and a weighted average total gold content was calculated. Currently, a new alternative method is being evaluated, where sub-sampling is done using rotary splitters, and fire assay on a 50 g sample; in this rotary sampling protocol and for comparison purposes, gold assays were also repeated using the leaching protocol.Test results were compared in three groups: < 0.3 g/t (below cut-off), 0.3 to 0.8 g/t, and >0.8 g/t. Overall, results show that the protocol established prior to start-up of operations underestimates the gold assays. Detailed technical results, alternative options, and their implications are discussed in the paper."

Jan 1, 2004

By X Yu, Y Shen

The iron ore products should be assessed in terms of in-furnace behaviour and overall furnace performance, their operation should also be optimised under industry-scale blast furnace (BF) conditions, in order to be sustainable and competitive, especially in the context of decarbonisation efforts in ironmaking. While lab and pilot-scale experiments can provide useful kinetics, they are expensive and risky and cannot replicate industry-scale blast furnace conditions for proper assessment and optimisation. In this paper, we review our recent progress at Shen Lab of UNSW in using state-of-the-art Computational Fluid Dynamics (CFD) models to assess iron ore products and examine the effects of their operations on BF behaviour in basic terms, including in-furnace phenomena (flow field, temperature field, species distribution fields etc) and overall BF performance (coke rate, reduction efficiency and top gas temperature etc). We have developed state-of-the-edge CFD models for different purposes, ranging from the static-state BF model featuring unique layered burden structures for offline assessment and optimisation knowledge building-up for iron ore products, to the transient-state BF model for online assessment and optimisation of iron ore productions by describing the transient behaviours of iron ore productions under industry-scale conditions. First, we have studied several iron ore products including the iron ore products used in the present BFs and emerging iron ore products like carbon composite briquette and iron-coke. Second, several iron ore operations are studied including optimisation of conventional burden operations like oxygen enrichment, batch weight tuning and new operations like coke central charging and hydrogen injection in BFs. Third, some time-sensitive operations are also investigated including the use of wet burden materials and the drop in blast temperature on BF performance. These CFD models offer cost-effective research tools for understanding the effect of iron ore products on BF performance and serve as a reliable marketing tool for existing and emerging iron ore products under a wide range of BF conditions.

Sep 18, 2023

By Paul R. Thomas

The Bureau of Mines evaluated the impact of the depletion allowance upon the economic availability of copper from domestic deposits. The potential long-run percentage depletion deduction, cumulated over the life of the properties, was estimated at approximately $2.5 billion for producing properties and up to $11.7 billion for nonproducers. The income transfer, in the form of higher Federal income tax payments if the allowance were repealed, was estimated at $1.5 billion for producing properties and up to $8 billion for nonproducers. The percentage depletion allowance, through its role in determining Federal income tax liability, was found to be very significant in affecting profitability. Repeal of the allowance could result in major domestic copper availability reductions at all price levels, now and in the future, as a result of reduced profit margins for current producers, and postponement of development decisions for nonproducers. It was demonstrated that a 50-percent reduction in the percentage depletion rate applicable to copper would also result in a significant decrease in profitability for nonproducing properties. For producing properties, the percentage depletion rate on copper was shown to be less significant than the income limitation that is placed upon the total amount of the depletion deduction. Repeal of the minimum Federal tax provision was shown to be significant in enhancing profitability for both producing and nonproducing deposits. The report concludes that the percentage depletion allowance operates as an important method of capital recovery and production incentive.

Jan 1, 1982

This article attempts to outline essential features of the Mount Isa ore deposit, to reveal the agencies thought to be responsible for its localization, and to describe methods used for obtaining and applying geological data on a commercial basis. Structural features are emphasized because they have proved the most useful agencies to date in searching for ore. Vertical depth, horizontal width and stratigraphic thickness are used throughout the article, and quantities are quoted in long tons.THE DEPOSITA width of more than two miles of evenly bedded shale of the Mount Isa series (upper pre-Cambrian) lies sandwiched conformably between quartzites. The series strikes N.S. and dips approximately 60&#176; W. Shale is unaltered...Important geological work has been carried out by the Queensland Geological Survey, chiefly by Mr. S. R. L. Shepherd, in co-operation with the Geological Department of Mount Isa Mines Limited. Selected references are The Queensland Government Mining Journal for December, 1931, January, 1932 (Rio Grande Lode); December, 19B2 (Black Rock Lode); October, 1933 (General structure); October, 1936 (Mount Isa Lode).

Jan 1, 1939

By Binbin Luo, Northeastern University, Chuanyao Sun, Jie Liu, Yimin Zhu, Yanjun Li

"A series of new type collectors a-bromo-saturated fatty acids, CH3(CH2)5CHBrCOOH (a-BHA), CH3(CH2)7CHBrCOOH (a-BDA), CH3(CH2)9CHBrCOOH (a-BLA), CH3(CH2)11CHBrCOOH (a-BMA) were synthesized from saturated fatty acids and bromine by solvent-free method (Hell-Volhard-Zelinski reaction) in laboratory. The micro-flotation tests of quartz mineral were conducted at a relatively low temperature of 15 °C. The adsorption mechanism of such collectors on quartz mineral surface were established by zeta potential measurements, in conjunction with the results of quartz micro-flotation tests. The flotation results showed that the collecting ability is in the order of a-BMA > a-BLA > a-BDA > a-BHA for the flotation of quartz mineral, which also demonstrating that the a-bromo-saturated fatty acids (a-BFAs) are new selective collectors for reverse flotation to remove quartz mineral from iron ores at a relatively low temperature.INTRODUCTIONThe requirement of higher pulp temperature to maintain the activity of fatty acid anionic collectors which have been widely applied in technological process of iron ores reverse flotation lead to a great deal of energy consumption.The purpose of this paper is to synthesize a new modified collector with carbon chains from eight to fourteen atoms, with strong electronegativity bromine atom introduced into a-carbon position to improve the activity and solubility of the reagent so that it can be adopted at a comparatively low pulp temperature. The collecting performances of these new collectors on quartz surface were studied, and the structure - properties were discussed in light of zeta potential measurements and quantum chemistry calculations."

Jan 1, 2016

By N. S. Dalal, V. Castranova, K. Van Dyke, V. Vallyathan, J. H. Kang

"We have reported previously that crushing or grinding crystalline silica results in the generation of silica-based radicals on the particulate surface and that these radicals can generate hydroxyl radicals in aqueous solution. Data in the present study indicate that freshly ground silica is more cytotoxic and is a more potent activator of alveolar macrophages than comparably sized aged silica. That is, compared to aged silica, fresh silica is 4.2-fold more potent in decreasing the membrane integrity of macro· phages; is 50% more potent in activating hydrogen peroxide secretion by macro· phages; and is 4.frfold more potent in stimulating cellular chemiluminescence. Prosil 28, an organosilane material, is an effective coating agent for fresh silica. It decreases the cytotoxicity of fresh silica by as much as 78% and decreases the ability of fresh silica to induce chemiluminescence from alveolar macrophages by 58%. The data suggest that surface radicals associated with freshly cleaved dust may be an important factor in the induction of pulmonary disease. Furthermore, treating dust with coating agents may substantially decrease toxicity. INTRODUCTIONThe U.S. Department of Labor estimates that over 1.25 million American workers may be exposed to crystalline silica and that nearly 60,000 may be at risk of developing some degree of occupational lung disease (Parkes, 1982; Peters, 1986). Occupations of concern include miners, stone quarry workers, sand and gravel workers, sandblasters, foundry workers, and glass workers. Acute silicosis is characterized by inflammation, alveolar lipoproteinosis, and the rapid development of respiratory disability (Banks, 1986). In contrast, chronic silicosis develops 20-40 yr after initial exposure and is characterized by the appearance of concentric hyalinized nodular lesions and the progressive development of dyspnea (Parkes, 1982; Ziskind et al., 1976)."

Mar 1, 1992

By Phillip A. Armstrong, Charles A. Lewinsohn, John H. Gordon

"This paper describes the opportunity offered by employing systems based on mixed conductive ceramics, in particular, ceramics conductive to oxygen ions and electrons, in reducing CO2 emissions from metallurgical production. Membranes based on these mixed conducting properties enable commercial viability of several attractive metallurgical processes. One of these processes utilizes modular, ceramic-membrane structures for the generation of pure oxygen, in tonnage quantity. The membrane-based systems offer significant capital savings and operating efficiencies in various metallurgical processes. The current status of this technology is summarized below.IntroductionCryogenic oxygen supply technology is currently the state-of-the-art for applications that require large quantities of oxygen (hundreds to thousands of tons per day). Cryogenic technology, however, requires substantial energy inputs and, hence, adds significant costs and emissions to processes. Furthermore, cryogenic oxygen supply technology is mature and there is relatively little potential for substantial capital cost reduction or efficiency improvement in coming decades. Non-cryogenic technologies offer a means to reduce the environmental footprint and cost of the oxygen supply facility in various applications.Ion Transport membranesCommercially available non-cryogenic air separation technologies, such as adsorption-based and polymeric membrane-based methods, do not afford the economies of scale that the cryogenic distillation enjoys. Therefore, industrial gas industry researchers began searching for alternatives to the relatively inactive and unselective polymeric membrane materials available. In the late 1980’s, Air Products began developing a new class of highly selective membrane materials with exceptionally high activity for oxygen transport. The materials constitute a class of oxide ceramics, and conduct both oxygen (as oxygen ions) and electrons in the same membrane, separating oxygen from air electrochemically. Numerous detailed process economics studies have shown that, based on these ion-transport membranes (ITM’s), the cost of oxygen can be reduced by approximately one-third relative to that obtained from state-of-the-art cryogenic oxygen supply technology, through a combination of capital cost savings and efficiency improvements. [1,2,3]"

Jan 1, 2008

By Erle I. Shobert

In the comparison and consideration of synthetic and natural materials, graphites represent a situation in which natural graphites amount to less than 10% of the total carbon and graphite production by weight, and less than 5% in dollar volume, There are few applications where it could not be re- placed by synthetic graphite. On the contrary, synthetic graphite materials can be engineered to cover an extremely wide range of applications. These include electrographite brushes for rotating machinery, pyrolytic graphite, graphite-impervious pipe, nuclear moderators, high purity spectrographic graphite, power tube anodes, graphite rotary shaft seals, and rocket nozzles. The special qualities of natural graphite and its limitations are delineated and the almost unlimited possibilities in artificial graphite materials are discussed.

Jan 1, 1964

By J Player, R de Vries, E Villaescusa, H Saw, R Hassell

The use of cemented rock fill (CRF) for support of open stope walls has increased in the Australian underground mines operations over the last five years due in part to its low capital cost. In open stoping the exposed CRF masses require adequate strength and stiffness, in order to resist the forces and to limit the displacement associated with movements in the rock mass surrounding the excavations. The CRF material preparation often involves the use of large particles, either from crushed rock or from development mining waste sometimes up to 1 m in diameter. However, the use of waste rock, which has a poorly graded particle size distribution may not achieve the required minimum target strength due to segregation and large air voids within the fill mass. This paper describes the optimisation of CRF strength by either crushing the waste rock or the addition of sand to the mix. Both methods increase the level of fines in the mix design. Cylindrical samples having 400 mm diameter and 800 mm heights were prepared for uniaxial compressive strength (UCS) testing. The UCS test was determined using the Western Australian School of Mines (WASM) large-scale static test frame. The laboratory results were compared with a database of large-scale CRF strength mixed without sand from a number of mine sites around Australia. The comparison shows a significant strength development in the CRF mixing with addition of sand for a given cement percentage. Due to the higher strengths achieved by the addition of sand and the crushing of the waste material these CRF types require less cement to achieve the same strength. This has the potential to improve the overall economics of open stope mining due to less dilution of the exposed fill mass.CITATION:Saw, H, de Vries, R, Player, J, Hassell, R and Villaescusa, E, 2017. Optimisation of cemented rock fill strength for open stope support, in Proceedings 13th AusIMM Underground Operators’ Conference 2017, pp 85–90 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Oct 16, 2017

By John C. Ferm

Although roof falls account for approximately half of the fatalities in underground coal mining, the factors that produce them are not clear. Mining methods can account for some, but in others the controlling factors are the geological setting in which the mining takes place. The present investigation was undertaken to determine the kinds of rocks that were most likely to produce roof problems. Such knowledge would be helpful to mine planning since rock samples can be obtained in advance of mining by core hole drilling. The investigation was undertaken in underground mines in the Pocahontas #3 seam in southern West Virginia and southwestern Virginia. The Pocahontas #3 is one of the most widespread in this region and is a major source of high quality metallurgical coal. There are at least ten very large mines in the area and many smaller ones. The region has a very long mining history and considerable experience has been gained in roof control problems. The study was conducted with the support of the U. S. Bureau of Mines.

Jan 1, 1978

By R. Kadeg, S. Pavlou

A methodology for developing and utilizing risk-based action levels for soils in site closures is discussed. The methodology is based on standard exposure pathway models which are consistent with current regulatory guidance on conducting risk assessment. A simple approach to evaluating the potential for contamination ground water from the projected criteria based on the Toxicity Characteristic Leachate Procedure (TCLP) is also presented.

Jan 1, 1992

By Natalie Swan, Carlos Santana

La ejecución de programas de monitoreo biológico es un desafío para la gestión ambiental de proyectos mineros, principalmente por la alta demanda de recursos y tiempo que requiere y la poca certeza sobre sus resultados. Por ello, se presenta el uso del ADN ambiental como una alternativa de calidad y probada eficiencia. La aplicación de análisis de ADN ambiental en un programa de monitoreo implica tener en cuenta aspectos sobre la ecología del ADN ambiental, las etapas requeridas para su análisis y el estado de desarrollo de las distintas aplicaciones existentes.

Sep 30, 2022

By R. Wang, N. J. Grant, B. C. Giessen

By crystallographic and X-ray methods, the existence and isonzorphism of Ti3Rh5 and Hf3Rhs were confirmed. Both phases are of the orthorhombic Ge3Rh5 type; lattice parameters and refined positional parameters are given. The structure is related both to the filled-up NiAs-B8 and Cu-AI types. An analogous phase with zirconium does not exist; the effect of ternary substitutions for titanium ad hafnium suggests a size factor limit to be active. A recent survey of phase diagrams of the T4 metals titanium, zirconium, and hafnium with the T, noble metals rhodium and iridium indicated the existence of the A3B5 phases Ti3Rhs, ZrsRhs, and HfsRhs. Ti3Rhs and Hf3Rh5 were found to be isostructural, based on the line-rich powder patterns which had not been analyzed. Zr3Rh5 was considered to have a substructure of the NbRu type (orthorhombically distorted B2-CsCl type).&apos; Because, in combinations with other transition metals, hafnium and zirconium are generally more likely to form isostructural phases than hafnium and titanium (with the significant exception of the Ti2Ni-"E93" type phases based on T4 metals2), the reversal of this relation for the A3B5 phases was of interest. As shown in the following, the nonexistence of Zr3Rhs has been established, the structures of Ti3Rh5 and Hf3Rh5 have been worked out, and crystal chemical relationships and stability criteria are reported. EXPERIMENTAL METHODS AND RESULTS Alloy Preparation and Phase Diagram Work. Alloys were prepared from high-purity (99.99+ pct) elements by arc-meltin3,4.Heat-treated alloys were annealed in a vacuum of 3 x X torr for 24 hr at 1300DC. Metal-lographic samples were etched electrolytically in concentrated HCl with 5 v ac for 5 min.3 X-ray diffraction powder patterns were taken on a GE XRD-5 dif-fractometer with Cum radiation at low scanning rates (0.2 deg per min for 28). It was confirmed that Ti3Rhs and Hf3Rh5 have similar diffraction patterns, and that an alloy with the composition Zr3Rhs has a different pattern. Six Zr-Fh alloys with 59 to 69 at. pct Rh were therefore prepared and investigated in the as-cast state by X-ray diffraction and metallography. Alloys at 59 and 61 at. pct Rh were found to be a single phase, with the distorted B2-CsC1 type structure typical for the off-stoichio- metric region of the phase (Zr,-,Rh,)Rh. This phase forms a eutectic with ZrRhs at about 66 at. pct Rh: accordingly, alloys between 61 and 69 pct at. pct Rh consisted of two phases. There is no evidence for the existence of Zr3Rh5. Based on the results in Rafs. 1 and 5, on the present work on Zr-Rh, and on several additional alloys investigated, the portions between the AB and AB3 stoi-chiometry for Ti-Rh, Zr-Rh, and Hf-Rh are as follows: Further, several ternary alloys near Ti3Rhs and Hf,Rhs were prepared in which it was attempted to replace titanium and hafnium partly by zirconium, niobium, tantalum, and germanium. The results will be discussed in a later section. Structure Determination of Ti3Rh5. Since Ti3Rh5 and Hf3Rh5 are isostructural, the following discussion will largely deal with the former. Although the powder pattern of TisRhs is complex, as found previously,1 it could be indexed by comparison with other structures of A3Bs stoichiometry. Ti3Rh5 was found to be isostructural with Ge3Rh5, whose orthorhombic structure had been elucidated by Geller.9 As both the sizes and atomic numbers of germanium and titanium are comparable, the unit cell volume and the peak intensities could be expected to be similar; however, significant differences exist in the atomic positions, as will be shown. All lines in the powder patterns of Ti3Rh5 and Hf3Rhj could be indexed with primitive orthorhombic unit cells with the lattice constants: The fractional errors are 10 The low-angle portion of the indexed powder pattern of Ti3Rh with sin2 8 < 0.30 is listed in Table I. The extinction laws Okl only with k = 2n and hOl only with h - 2n are compatible with the space group Pbo2 and the more symmetrical space group Phnm of Ge3Rh5. Finally, the positional parameters of Ti3Rh5 and HfsRhs were refined under the assumption that titanium and hafnium occupy the germanium positions in Ge3Rh5. Integrated intensities were obtained from the diffraction patterns by planimetry. Intensities of overlapping reflections were separated by an iteration process incorporated into the least-squares positional refinement program according to a method described previously. The intensities of Ge3Rh5 were used in the first separation cycle, while the atomic parameters of Ge3Rh5 were used as starting values in the first refinement cycle. Absorption due to specimen

Jan 1, 1970

From a gathering storm of climate change based legislation that could potentially overwhelm the mining industry, to the nuts and bolts of mineral processing and just about everything in between, about 100 mining and mineral processing professionals heard it at all at the 60th annual Colorado MPD Meeting April 22-24 at the Broadmoor in Colorado Springs, CO. With a sweeping agenda under the banner ?What in the world is new in mining and metallurgy? attendees were treated to four sessions and 21 presentations that covered the range of mining industry issues. Bill Reid, president, chief executive officer and director of Gold Resources Corp., spoke about his company?s El Aquila gold project in Mexico. With five projects in Mexico, Gold Resources Corps. is aiming to become a low-cost gold and silver producer. Its flagship property, the El Aguila gold project, is a high-grade gold and silver property with significant base metal credits of copper, lead and zinc. Production of the El Aguila project was targeted for mid-2009. Reid said that three high-grade deposits have been discovered at the El Aguila project. They include the high-grade ?manto? style El Aguila openpit deposit, the El Aire high-grade polyme-tallic vein system, which is underground, and the underground La Arista high-grade polymetallic vein system. The project is located 120 km (75 miles) south-east of the capital city of Oaxaca, Mexico. Reid said the property has yielded several exceptional gold and silver surface samples, including a 36-g/t (1.1 oz/st) gold sample and a 3,100-g/t (90 oz/st) silver sample. Other properties that Gold Resource Corp. has are:

Jul 1, 2010

By J. I. Budnick, W. B. Ittner III, D. P. Seraphim

A reliable technique has been developed for producing single crystals of tantalum in the form of small diameter wires. By suitably heat treating these and polycrystal samples, first in an oxygen atmosphere and finally in vacuum, it has been found possible to reduce residual resistivities to 10-3 microhm-cm. The purity of these samples is thus comparable to the purities obtained in zone-refined silver, copper, and aluminum. THE growth and purification of pure single crystals of the transition metals is, in general, difficult. The high melting and annealing temperatures of these metals make it necessary to employ rather special techniques in any crystallization process. In addition, the transition metals show a great affinity for and are easily contaminated by nitrogen, oxygen, and carbon. Recently, however. a number of investigators have been successful in growing,

Jan 1, 1961

By Kampe. S. L., Baker. Andrew H., Tony Zahrah

"Experimental heats of reaction for the formation of several Al3Ti + TiB2 intermetallic composite formulations have been determined utilizing bomb calorimetry. To overcome the kinetic constraints and achieve ignition in these formulations, a boron (B)/potassium nitrate (KNO3) initiation aid was incorporated within the blended reactant compact. The heat contribution from the initiation aid was regressed to provide estimates of the heat of reaction of the nominal formulations. Powder x-ray diffraction was utilized to identify the products of the reaction and discern any differences between the predicted equilibrium products of the formulation and the actual products.IntroductionReaction synthesis is a technique for the creation of ceramics, intermetallics, and in-situ composite materials [1]. Reaction synthesis is defined by its self, propagating mechanism, where the energy liberated from a localized reaction within a green powder compact is enough to carry the bulk reaction to completion. Achieving a self, propagating state can be achieved in variations of two primary methods of initiation: uniform volumetric heating and directional propagation [2].Uniform volumetric heating involves subjecting a green compact of the unreacted formulation to uniform heating in a furnace to encourage diffusion to initiate the reaction (Figure 1a) throughout the bulk material. Directional propagation utilizes a point heat source at one section of a green compact of unreacted formulation (Figure 1b). The localized exothermic reaction at one point in the compact then initiates the reaction in the section of the compact adjacent to it and fully propagates throughout the entire compact until completion. Initiation of the localized reaction is generally associated with the melting of the constituent with the lowest melting point, with instantaneous initiation of the reaction usually occurring close to that melting point [1]. This melting point can be high in some systems of interest, such as the titanium (Ti) and boron (B) system in equation 1:"

Jan 1, 2011