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By J. J. Gilman

Rates of prisnzatic plastic glide ( {1010}<2110>) in pure Cd crystals have been measured at temperatures from 158° to 276°C. The glide rate is proportional to the 2.75 power of the applied shear-stress. The activation energy is 29.2 kcal per mol. It is suggested that the rates of prismatic glide in Cd and Zn crystals are determined by the strengths of the atomic bonds across the prism planes. ALTHOUGH zinc and cadmium crystals both have hexagonal structures with nearly the same c/o ratios, their mechanical behaviors are quite different. Whereas zinc becomes quite brittle below room temperature, and cleaves readily on (0001) planes, cadmium is very ductile even at 4.2°K, and cannot be cleaved at any temperature. As part of a search for the explanation of this difference in behavior, a study has been made of prismatic glide in cadmium. It complements a previous study of the same phenomenon in zinc.1 The primary glide plane in cadmium is the basal (0001) plane, and the primary glide direction is the direction of atomic close-packing <2110>. However, if a tensile stress is applied parallel to the basal plane, then the shear stress on the basal plane equals zero so basal glide cannot occur. At low temperatures, deformation by twinning occurs; but at high temperatures, it has been found in this study that gliding on prismatic planes (1010) occurs in the close-packed direction. This is completely analogous with the case of zinc, except that lower temperatures are required. EXPERIMENTAL The experiments were done in nearly the same way as for zinc.&apos; Therefore, only the differences in the two sets of experiments will be described here; for other details the reader is referred to the previous paper. Crystals 6 by 6 mm sq were used that were grown from "Super Purity" 99.999 + pct Cd purchased from the New Jersey Zinc Co. The crystals were grown with their basal planes parallel to both the rod axis and one of the flat sides of the square cross section, A close-packed direction in the basal plane was oriented parallel to the rod axis. Gage sections were carefully machined into the crystals, and the surface damage caused by machining was removed with the same chemical polishing reagent as had been used for zinc. Thus, specimens of the same form and size as the previous zinc ones were produced. The crystals were heated to the test temperatures in a silicone oil bath (fused salts were tried first, but they reacted badly with the cadmium). An Instron tensile-testing machine was used for applying stresses to the crystals at various constant strain-rates. RESULTS The general behavior of cadmium crystals is much the same as for zinc. Only the constants that measure specific properties are different. Just as

Jan 1, 1962

By Faruk Oksuz, Dave Schiemann, Matt Trotter, Mike Padilla, Carmen Scalise, Miquel Sanchez

"The McCook Main Tunnel system consists of a 10-m (33-ft) finished diameter, 490-m (1,600-ft) long, hard rock tunnel constructed from a 27.5-m (90- ft) diameter and 92-m (300-ft) deep main gate and tunnel construction access shaft. The gate shaft houses six, high-head 4.4 m by 9 m (14.5 ft by 29.5 ft) wheel gates to be installed in the bifurcated and steellined section of the tunnel. The tunnel also includes portal and energy dissipation structures as it daylights into the reservoir.The construction of the tunnel system has been divided into two contracts. The gate and construction access shaft was completed in August 2011. The tunnel excavation and concrete and steel lining was completed in September 2014. The remaining and undergoing construction include the tunnel connections to the reservoir and the Mainstream Tunnel and installation of gates and hydraulic cylinders. This article focuses on the live connection of the McCook Main Tunnel to the Mainstream Tunnel that was initiated in November 2014 and will continue through the seasonal drier weather conditions in Chicago approximately from October through April. Chicago TARP systemThe MWRD has been addressing combined sewer overflows (CSO) and flooding in Chicagoland since the late 1960s and formally adopted the tunnel and reservoir plan in 1972 to protect the region’s most precious drinking water supply, Lake Michigan. Phase I of TARP, which included construction of 175 km (109 miles) of deep storage and conveyance tunnels with diameters up to 10 m (33 ft), was completed in 2006. In addition to protection of Lake Michigan from CSO discharges, Phase I resulted in substantial improvements in surface water quality as well as the quality of life for lake and riverfront communities in Chicago. Water quality improvements and flooding mitigation will be further enhanced as Phase II reservoirs are placed in service, including the three large reservoir systems, McCook, Thornton and Majewski (Fig. 1).The McCook Reservoir is the largest reservoir in the TARP system. Once completed, this $700-million reservoir facility will receive 38 billion L (10 billion gal) of CSO and flood water via the McCook Main Tunnel, which connects the TARP Mainstream Tunnel to the McCook Reservoir, and from distribution and Des Plaines inflow tunnels which will bring flow from the Des Plaines Tunnel of TARP."

Sep 1, 2016

By C. Stansfield Hitchen

The paper describes the application of the logarithmic wedge sector method of quantitative spectrography to the estimation of commonly occurring minor impurities in crude and refined tin. Both arc and spark methods of emission were employed and with the former a new device was used to overcome difficulties arising from the low melting point of the metal. The impurities investigated included antimony, arsenic, bismuth, copper, iron, lead, and zinc, their concentrations lying, in general, between 0.01 and 0.50 per cent. The results obtained show that the method may be usefully employed for the estimation of bismuth, copper, iron, lead, and zinc, in amounts ranging from 0.50 per cent to well below 0.01 per cent. Arsenic and antimony, however, could not be estimated in amounts less than 0.03 and 0.07 per cent respectively. Out of a total of 116 estimations by arc and spark emission, in 96 the errors were less than 5 per cent of the total quantity of the element present, whereas in the remaining twenty, the errors lay between 5 and 25 per cent. Spectro-analytical data for the several impurities studied are given in the form of tables, and curves correlating line-intensity with concentration have also been included. DISCUSSION (R. G. Waltenberg presiding) D. M. Smith, London, England (written discussion).—I am interested in Dr Hitchen&apos;s account of his investigations on the application of spectrographic methods to the assay of tin and congratulate him on his valuable contribution to the literature on the subject of quantitative spectrum analysis. Some of the results obtained in the course of investigations carried out for the British Non-Ferrous Metals Research Assn., although obtained under somewhat different experimental conditions, may be of interest in connection with this paper. Arc and spark spectra of standard samples of tin containing various known amounts of antimony, bismuth, cadmium, copper, lead, silver and arsenic have been investi-

Jan 1, 1933

By Qingwen Dai

The Marangoni effect is an important phenomenon where a surface tension gradient drives liquid towards high surface tension regions. Temperature gradient, evaporation, disparity of viscosity, and surface roughness and topography are all significant factors that can affect this thermo-capillary migration. The purpose of this study was to investigate the influence of micro-groove patterns on the migration of paraffin oil, and obtain a well-designed texture of micro-grooves to prevent the thermo-capillary migration. Patterns of micro-grooves with differing orientations and geometric parameters were fabricated on the surface of SUS 316 stainless steel substrates. Experiments on the migration behavior with different viscosities of paraffin oils were carried out various temperature gradients. The experimental phenomena indicated that the surface with the micro-grooves perpendicular or parallel to the temperature gradient have a strong impact on the migration performance of paraffin oil. Micro-grooves perpendicular to the temperature gradient exhibited extraordinary slower migration velocity than that of the parallel one. Width and depth of micro-grooves had an obvious influence on the behavior of temperature-driven migration and detail discussions on the effects of these geometric parameters were carried out.

Jul 31, 2018

By J. A. Mejia

The combination of high-resolution X-ray microtomography (HRXMT) image analysis and Lattice-Boltzmann Method (LBM) simulations has demonstrated the ability to describe real multiphase flow problems in fine coal filtration. The single component multiphase flow He-Chen-Zhang LBM model was used to simulate filtration with actual HRXMT images of pore network structures produced in filtration experiments. The analysis performed on coal, silica, and glass bead filter cakes showed that particle shape and wettability are two of the most important factors in the retention of moisture during filtration.

Feb 23, 2014

By T. T. Campbell

This investigation was undertaken by the Bureau of Mines to determine if high-purity ductile molybdenum of uniform quality can be prepared by bomb reduction techniques. Molybdenum trioxide (Mo03) and mixtures of molybdenum dioxide (Mo02) and trioxide were reduced by magnesium in closed steel bomb reactors. Very high pressures in excess of 5,000 p.s.i. developed during magnesium reductions of Mo03. The addition of calcium oxide to the bomb charges caused a significant reduction in pressure. Reaction efficiencies higher than 95 percent were obtained during magnesium reductions of either Mo03 or mixtures of Mo02 and Mo03, but high pressures were encountered when the charges contained from 30 to 60 percent Mo02. Reaction efficiencies were usually low (less than 80 percent) when the bomb charges contained more than 40 percent Mo02. The charges with the best composition considering operating pressure, yield, and purity contained from 10 to 30 percent Mo02. The addition of small amounts of carbon to the reaction charges was helpful because some deoxidation occurred during the reduction and also during subsequent arc-melting of the regulus metal. The purity of the bomb-reduced, arc-cast molybdenum metal ranged from 99.2 to 99.8 percent and in some instances the metal contained as little as 5 parts per million oxygen.

Jan 1, 1962

By Ernest L. Corp

The natural marine environment can be divided into four basic categories: the air-sea interface, the water zone, the seafloor, and the subbottom. Efforts are being made to accumulate data to delineate the conditions in each of these areas and to conduct engineering studies which will determine how these environmental parameters affect the mining process. Laboratory facilities have been constructed and equipment and techniques for scientific data collection and laboratory research have been developed. Major emphasis is being placed on studying the subbottom material. The objective of this emphasis is to study the engineering properties of marine placer deposits in order to assess their influence on the design and performance of the various mining subsystems involving penetration, excavation, transportation, and disposal. Presented are the results of engineering properties tests on a placer simulant which is currently being used for model and prototype testing of coring tools. The effect of these engineering properties on penetrability, core recovery, and sample recovery is discussed.

Jan 1, 1970

By V. H. Gottschalk, R. S. Dean

In the theoretical study of metallurgical reactions, it is necessary to make certain assumptions concerning the nature of metal-gas systems. The assumption usually made is that the reaction in such systems takes place predominantly with gas that is in "solution" and that the amount of solution follows the rules which have been developed for aqueous solutions; namely, Henry&apos;s law. The purpose of this paper is to inquire whether these assumptions are the best ones that present knowledge of gas-metal systems permits us to make. In the first part the extent to which a gas will dissolve in a metal and still follow Henry&apos;s law is considered. The conclusion is believed justified that the number of molecules of gas that can dissolve in a metal and have the system follow Henry&apos;s law must be small indeed. It is therefore improbable that the first assumption concerning the predominance of these dissolved molecules in reaction is correct. It is suggested that some improvement in the correlation of the probabilities with the assumptions made in the mass law equations would be made by the use of the dp law of Sieverts in place of Henry&apos;s law. However, the amount of gas that may be held in a metal so that it follows either Henry&apos;s or Sieverts&apos; law is considerably outweighed in most metallurgical reactions by that held in gas-metal systems of entirely different structures and concerning which little experimental evidence is available. Some speculation concerning the nature of these is offered. The conclusion is that attention should be given to the determining of the nature of gas-metal systems and that the really fruitful application of the mass law and its connected calculations will have to await a more complete knowledge of these systems than we now possess. DISCUSSION (Paul D. Merica presiding) P. D. Merica, New York, N. Y. (written discussion).—The solubility relations of gases in metals, in so far as they are known from the pioneer work of Sieverts and others, have from the first presented certain challenging peculiarities. The authors have emphasized the significance of these characteristics and suggest that they point

Jan 1, 1933

By Michael J. Beus, Stephen Iverson

BACKGROUND A mine shaft is the lifeline to underground mines. Mine operators depend on safe, uninterrupted, and efficient movement of workers and materials. The shaft and hoisting system provides access to the network of openings used to recover the underground resource, provides vertical transport of miners and materials, and serves as an escapeway in case of an emergency. Accidents involving hoisting can be catastrophic. Such was the case in 1973 at the Markham Colliery in Derbyshire, UK when the conveyance overwound and fell to the shaft bottom, resulting in 17 deaths. Hoist and elevator machinery must meet the requirements specified in the Code of Federal Regulations (CFR), Parts 57 and 75. According to the Mine Safety and Health Administration (MSHA) data, many shaft-related accidents in the United States are associated with the hoisting cycle. MSHA statistics show that there were about 1500 shaft- related accidents in the 5-year period between 1992-1996. Most of these accidents resulted from the action, motion, or failure of the hoisting equipment or mechanism and involved movement of the conveyance which includes cages, skips, ore buckets, and elevators. A hoisting hazard may be characterized as an "unsafe hoist operating condition caused by insufficient or inaccurate information available to the hoist operator" (authors&apos; quote). Earlier investigators have defined safety features and operating and maintenance standards for hoists, and reported on monitoring and control systems and sensors for hoists and conveyances [Farley, 1983; Ward, 19931. However, despite the considerable technological progress and hoisting control improvements in recent years, safety- related issues that require further investigation still remain. The hoist operator must constantly be aware of two important hoist-operating conditions: the position of the conveyance and the tension in the hoist rope. If this information is not available or is inaccurate, the hoist becomes unsafe. Current technology provides this information indirectly from sensors and indicators in the hoist room. However, unlike a building elevator hoistway, mine shaft hoistway problems often include: 1. poor ground conditions and excessive shaft wall and guide displacement; 2. rock bursts in deep mines (resulting in large rock movements and fragments blocking the hoist way); 3. water, ice, and salt buildup (impeding the smooth flow of the conveyance); 4. severe vibration from hoisting (resulting in loose guide support brackets, broken welds, or other alignment and conveyance mechanism malfunctions). The second issue relates to dynamic rope loads applied during normal winding, particularly during loading, acceleration, and stopping. Safety factors on wire rope are based on static load. They are artificially high to account for all cases of dynamic loads, even though the total load history on the rope (static and dynamic) during service is unknown. Therefore the tension, and thus the compliance with wire rope load safety factors, is unknown to the hoistman.

By Martin Bolesta

The use of strata injection as a means of stabilizing brittle and heavily stressed ground as well as faulted zones is now state-of-the art technology. Users are obliged to select the right combination from a wide range of injection products and equipment in order to ensure that the operation will be a success. Laboratory tests and a fundamental understanding of the technical aspects of injection products not only help in drawing up the correct injection procedure but have in fact become indispensable for planning the most reliable and cost-effective solution.

Jan 1, 2001

By M. Soya, M. Imazu, Ö. Aydan

"SUMMARY Taru-Toge tunnel is being constructed using drilling-blasting technique as a part of expressway project connecting Shin-Tomei Expressway and Chuo Expressway at the boundary of Shizuoka and Yamanashi Prefectures in the Central Japan. The maximum overburden is about 400 m. The authors have been carrying out a monitoring program to measure dynamic and multi-parameter responses of tunnel during and soon after the blasting operations using a multi-parameter monitoring system (Acoustic Emissions (AE), Electric Potential (EP), Temperature (T), Humidity (H) and Air Pressure (P)) and stand-alone type compact accelerometers developed by the first author. The measured response involves dynamic vibrations and other measurable parameters caused by blasting as well as by stress-redistribution around the tunnel face. This is one of the first attempts in the world to measure the response of rock mass caused by blasting at a very close vicinity of the tunnel face. In this paper, the authors present the outcomes of this unique monitoring study on the dynamic responses of the Taru-Toge tunnel during excavation and discuss their implications in actual applications. INTRODUCTION The real time monitoring of the stability of tunnels are of great importance when tunnels are prone to failure during excavation such as rockbursting or squeezing (i.e. Aydan et al. 1993, 2001). Experimental studies by the authors showed that rock indicates distinct variations of multi-parameters during deformation and fracturing processes (i.e. Mizutani et al. 1976; Aydan and Daido 2002; Aydan et al. 2003, 2011). These may be used for the real-time assessment of the stability of rock structures. An application of this approach was done to the Taru-toge tunnel a part of expressway project connecting Shin-Tomei Expressway and Chuo Expressway at the boundary of Shizuoka and Yamanashi Prefectures in the Central Japan (Imazu et al. 2015). The parameters measured involve electric potential variations, acoustic emissions, rock temperature, temperature and humidity of the tunnel in addition to the measurements of convergence and loads on support members during the face advance."

Jan 1, 2016

By A. Norholm

For grinding Portland Cement, the power consumption accounts for some 35 % of the total consumption of electrical energy for producing cement, counting right from the quarry to the packing plant. It is therefore for very good reason that great efforts during the past years have been put into making cement grinding more efficient, thereby saving power. In this paper three ways of reducing the consumption of electrical energy will be described, namely precrushing in the high pressure FLS-Köppern roller press, the introduction of a new design of COMBIDAN diaphragm in ball mills and the separation of mill discharge in the newly developed high efficient; separator SEPAX from F. L. Smidth.

Jan 1, 1987

By J. Kuijpers

Failure and fracturing are often regarded as synonymous. While this is obviously true in an environment dominated by tensile stresses, it is still not clear how failure and macro fracturing are related in a compressive stress environment. Excavations at great depths are typically subjected to compressive stresses only. The fracturing observed around such excavations is therefore commonly assumed to be induced by such compressive stresses. The physics of such a phenomenon have unfortunately never been explained properly, so that the formation of these so-called extension fractures still remains a mystery. As the presence of fractures is an important factor affecting the stability of underground excavations, it is of practical relevance to understand their formation. In this paper, a possible explanation is proposed. It is argued that fracturing in a compressive stress environment is a secondary effect. Primary failure, in the form of micro fracturing and associated damage is assumed to precede the major fracture processes. The fractures are thus generated in response to material failure and may not directly be the cause of failure. The implications for material response and behaviour are discussed. Keywords: micro fracturing, macro fracturing, extension fractures, failure, compressive stresses, damage, excavations.

Jan 1, 2000

By J. -M. Rescoussier

Due to Important settlements inducing major structural damages, the western part of the Grand Littoral shopping centre has been closed in 1997. The present paper describes the project of underpinning including not only micropiles under the structure of the building but also a reinforcement of the soil located between the shopping centre and the edge of the embankment surrounding the western part of the shopping centre. The aim of this reinforcement is to reduce existing horizontal movements to allowable values.

Jan 1, 2002

By Ricardo Miranda Alé

Aços resistentes ao serviço ácido (sour service), com requisitos adicionais de alta resistência mecânica e tenacidade, têm sido especificados para aplicação em gasodutos do Pólo Pré-sal da Bacia de Santos. O desenvolvimento de aços que atendam a estes severos requisitos, visando à fabricação de tubos de elevada espessura, constitui um enorme desafio para o fabricante do aço. No presente trabalho, é apresentado o desenvolvimento do aço API 5L-X65 Sour Service para esse tipo de aplicação, onde são descritas as principais ações realizadas no processo de produção que permitiram o sucesso no desenvolvimento do produto, confirmado pelas excelentes propriedades obtidas nas chapas e nos tubos.

Aug 8, 2018

By Jackson de Brito Simões

As Ligas com efeito de Memória de Forma (LMF) são metais funcionais que podem recuperar grandes deformações, superiores a 5%, quando submetidos a carregamento mecânico e/ou aquecidos. Este fenômeno ainda surpreende pesquisadores e engenheiros de projetos, materiais e processos. Esses metais possibilitam o desenvolvimento de atuadores termomecânicos capazes de gerar esforço mecânico com o bloqueio da recuperação de forma. Inúmeros são os processos para obtenção dessas LMF, cada um com sua particularidade e limitação específica. Nesse contexto, este trabalho avalia o efeito do reprocessamento pela técnica Plasma Skul Push-Pull (PSPP) e do tratamento térmico de solubilização nas propriedades térmicas de transformação de fase de uma LMF 55,1Ni-44,9Ti (% em peso) obtida originalmente pelo processo de fusão por indução a vácuo (VIM). Para isso, a LMF foi refundida com uma tocha de plasma e vazada sob pressão em quatro moldes metálicos distintos (aço, bronze, alumínio e cobre). As técnicas de caracterização térmica Calorimetria Diferencial de Varredura (DSC) e Resistência Elétrica em função da Temperatura (RET) foram utilizadas para avaliar o efeito desse reprocessamento e do subsequente tratamento térmico de solubilização a 850°C em diferentes tempos. Verificou-se que a injeção em molde metálico proporciona uma significativa redução nas temperaturas de transformação de fase, da ordem de 30°C em relação ao material bruto obtido por VIM. Por fim, foi possível concluir que a LMF NiTi reprocessada mantém a transformação de fase mesmo após tratamentos de solubilização a 850°C em tempos mais longos (8 h), contrariamente ao material originalmente obtido por VIM.

Aug 16, 2017

CHARGING of an open-hearth heat is begun as soon as possible after the previous heat has been tapped. Ordinarily, about 40 min is required to drain and dress the furnace hearth, make up the taphole, and perform routine repairs of the banks. Repairs to the upper back wall and to the front wall and jambs can ordinarily be done while the first scrap charge is being heated and are therefore allowed to wait in order to save furnace time. Any major repairs required on the hearth or other parts of the furnace necessitate longer delays because such repairs must be made while the furnace is empty. Although charging practice varies considerably in detail with the type and proportions of scrap and iron used, many factors are common to all varieties of charge. Such general considerations are dealt with first. CHARGING EQUIPMENT AND STOCK HANDLING The physical equipment available for loading and weighing the stock, transporting it to the furnace, and charging it, may have a major effect on charging practice. Limestone, scrap, and all other solid melting stock are charged mechanically by means of equipment illustrated in Fig 2-1. The charging of hot metal is shown in- the background of this figure. Mechanical equipment and plant layout for stock handling are described in Chapter 1. It is generally desirable to charge the scrap about as fast as the physical volume can be put into the furnace. Charging scrap that is too heavy or adding the charge too rapidly (less than 45 min) may be detrimental to melting rate because of excessive chilling of the entire furnace system and also because of poor conduction of heat to the lower layers in the furnace; but the more common problem is the reverse one of charging light scrap fast enough to maintain a normal heat time. A limiting factor may be the height to which the scrap may he piled in the fur-

Jan 1, 1964

CHARGING of an open-hearth heat is begun as soon as possible after the previous heat has been tapped. Ordinarily, about 40 min is required to drain and dress the furnace hearth, make up the taphole, and perform routine repairs of the banks. Repairs to the upper back wall and to the front wall and jambs can ordinarily be done while the first scrap charge is being heated and are therefore allowed to wait in order to save furnace time. Any major repairs required on the hearth or other parts of the furnace necessitate longer delays because such repairs must be made while the furnace is empty. Although charging practice varies considerably in detail with the type and proportions of scrap and iron used, many factors are common to all varieties of charge. Such general considerations are dealt with first. CHARGING EQUIPMENT AND STOCK HANDLING The physical equipment available for loading and weighing the stock, transporting it to the furnace, and charging it, may have a major effect on charging practice. Limestone, scrap, and all other solid melting stock are charged mechanically by means of equipment illustrated in Fig 2-1. The charging of hot metal is shown in the background of this figure. Mechanical equipment and plant layout for stock handling are described in Chapter 1. It is generally desirable to charge the scrap about as fast as the physical volume can be put into the furnace. Charging scrap that is too heavy or adding the charge too rapidly (less than 45 min) may be detrimental to melting rate because of excessive chilling of the entire furnace system and also because of poor conduction of heat to the lower layers in the furnace; but the more common problem is the reverse one of charging light &apos;scrap fast enough to maintain a normal heat time. A limiting factor may be the height to which the scrap may he piled in the fur-

Jan 1, 1951

By M. E. Lewellyn

A lower moisture content for a clean coal product means increased Btu content, or increased yields at the same Btu content, and lower operating costs. The conventional surfactant-based dewatering aids effeciently lower the moisture content but often the presence of residual surfactant in the filtrate and recycle water causes problems downstream. ACCOAL-DRI 1000, a surfactant-based dewatering aid, was developed to solve this problem by minimizing the downstream effects while efficiently lowering the moisture content. The theory of the use of surfactants in filtration will be discussed as well as the development and field evaluation of this new product.

Jan 1, 1988

What is your assessment of the mining industry as we near the end of the 20th century? As it always has, the industry is continually changing. The recent rate of change has been hectic. Many mining-related commodities are selling at low prices. These include gold, silver, copper, coal and soda ash, to name a few. Lower prices place pres- sure on mining companies to increase efficiency through productivity, down- sizing or mergers. The short- term effect of this situation may adversely affect the individual SME member. But the long- term benefit is to build a stronger, more productive and internationally competitive mining industry. In addition, most of these metals and minerals have been historically cyclical in nature, and prices will rebound.

Jan 1, 1999