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By Kirk A. Mcintosh

Augered, cast-in-place (ACIP) piles have been utilized in the United States for a wide range of projects since the 1950's. Due to the cast-in-place nature of the installation method (and lack of a driving criteria); however, ACIP piles have not been readily accepted by some practicing geotechnical and structural engineers. Since ACIP piles were initially developed, the installation equipment and techniques have been improved and refined and the number of experienced contractors has significantly increased. Over the past 10 to 15 years, the pile type has experienced significant growth in the United States (particularly in Florida) because engineers have become more knowledgeable and comfortable with its use. The Miami area, in particular, has experienced considerable growth in the utilization of ACIP piles primarily due to their usage on the $1 billion Miami Metrorail System project in the early 1980s. The economic advantages over other deep foundation types, coupled with some unique installation advantages, have shown that ACIP piles can be a viable foundation alternative on many projects. Even though ACIP piles have gained respect in the private sector, the pile type has generally not been readily accepted by government transportation agencies. The reluctance to readily accept this foundation type stems primarily from the quality assurance aspect of cast-in-place pile construction. Additionally, there has not been much research activity on this foundation type, technical papers, formal associations (other than the DFI), or a concerted effort to standardize the industry. This paper serves to discuss the state of practice for ACIP pile installation in the state of Florida.

Jan 1, 1997

By A. Subbotin

During developing the Ingulska mine at the Mi-churinske uranium deposit in the central part of Ukraine the radioactive rock dumps have been piled. A height of dumps reaches to 15-25m. They occupy a large territory and can be a source of covering with radioactive dust the area around the Ingulska mine. Uranium content exceeds 0,01% in all dump rocks samples while in the dust fraction samples it ranges from 0,01 to 0,06%. Uranium content in road dust at the dump?s foot reaches 0,137%. A new (for Ukraine) method of f-radiography of tree and bush leaves sampled at the territory about 100km2 has been used. It is based on fission of 235U nucleuses due to heat neutron influence in a nuclear reactor and on following study of the Lausan films with tracks drawn by the fractures of these nucleuses. Uranium content of the dif-fusion-disseminated dust type is (0.9-22.2)?10-6% while in the individual particles it can be considered much more because of burned holes in Lavsan above them. The dust content with uranium in Kirovograd reaches to 20-50 part/cm2 while near the dumps it ranges from 100 part/cm2 to 300 part/cm2 in the radius of 1,5-2km from the Ingulska mine.

Jan 1, 2005

By Aldo F. Barsotti

The production and consumption of industrial minerals in the United States traditionally have played important roles in mining and in the supply of the bulk of basic raw materials to the economy. This diverse group of minerals extracted and consumed by a variety of industries accounts, on a weight and volume basis, for most mineral-based products consumed in our economy. Industrial minerals form the bulk of the basic raw-materials feedstock for most of the construction, agricultural, and inorganic-chemical-manufacturing sectors, and a good portion of the transportation, manufacturing, organic chemical, and service sectors of the U.S. economy. In this presentation, I discuss current estimates of the amount and value of industrial minerals mined compared with all mining in 1997. I then present a summary of 1997 production of industrial minerals by several end-use industries. This is followed by a historical perspective of the consumption of industrial minerals as a subset of all basic materials, with special emphasis on the aggregates industry. The presentation concludes with a look at the geographic distribution of industrial mineral operations in the United States and some thoughts about the future.

Jan 1, 1999

By R. A. Hevia

Florida Power and Light is the fifth largest investor-owned electric utility in the country. It has a service territory that covers 35 counties, or 28,000 square miles, 2.5 million customers, and serves 5.6 million people. The total installed capacity is 13,470 MW, generated by four nuclear units, 36 oil and/or gas fired units, and 48 gas turbine units. Traditionally, FPL has been an oil-based utility. In 1979, this dependency on oil became obvious when 42 million barrels of oil were burned during the year. At that time, it was also projected that, based on the current estimates of customer growth and available generation capacity through 1990, FPL's residual fuel oil consumption would increase from the 1979 level of 42 million barrels (6.7 million m3) per year to approximately 55 million barrels (8.7 million m3) per year by the mid-1990's. Concern over this was further aggravated by the fact that it was difficult to estimate both the price and quantity of fuel oil that would be available over the next decade since changes in the world market, decisions by oil producers and refiners, and international political developments would all affect the availability of oil. Also, at that time, the price of residual fuel oil had increased drastically, and there was no reason to think that these prices would soon stabilize. Thus, oil back-out became a primary objective of FPL and since then, FPL has been actively investigating ways to decrease fuel oil consumption.

Jan 1, 1985

By John Chipman, Raymond L. Orr

Recently reported high -temperatlnre thermal data have been incorporated in a reuieu' of the therinody-r~ar,zic propesties of iron. The recent data permit mot corlsisterlt and reliuble choices to be made for many of the pvoperties, resnlling in bettev eslablished tabrtlations of the thermodynamic functions. Values of Cp, h°t- - H°298. s°t - S2sa, and (G°T -H298/T are tabulated for -the solid and liquid phases of iron in both stable and melastable regions. Consistency of the tabulations has been maintained to the precision necessr~vg to yield the Gibbs energy change belween the bcc (a, 8) and fcc (y) phases of iron at temperatures pertinenl to alloy studies. THE importance of the metal iron has stimulated many investigations of its thermodynamic properties at elevated temperatures. Reviews and summaries of the data have appeared from time to time. Among these the 1951 paper of Darken and smith' deserves highest recognition for the quality of its criticism and for the precision and thermodynamic consistency of its tabulations. These and the more recent table of Kaufman, Clougherty, and weiss2 reproduce the Gibbs energy of the (a, 6)--Y transformation with sufficient sensitivity for alloy studies. Other recent compilations of equal validity3-' make no attempt to do this. Since this Gibbs energy change is not greater than 22 cal per g-atom over the temperature range 1100° to 1800°K, it is obviously desirable to tabulate values of (G°t - H298)/T to four places of decimals even though the absolute accuracy would not warrant such precision. The necessity for reconsideration of the problem is emphasized by the recent publication of several important researches on the enthalpy and heat capacity of iron. The older work is well-covered in the reviews cited and will be mentioned here only when actually employed in the tabulations. GAMMA IRON Transition temperatures are taken from the selec -tions of Elliott and Gleiser,5 based on the work of Boulanger7 and earlier workers. For the a-y (A3) transition at 1184°K we retain the value 215 cal per g-atom adopted by Darken and smith.' It has received confirmation in the recent work of Dench and Kubaschewski,' and of Braun8 using adiabatic calori-metry, and of Wallace, Sidles, and Danielson10 using a pulse heating technique. The enthalpy data of Olette and ferrier" and of Anderson and Hultgren12 at higher and lower temperatures may be extended to 1184°K to give the following values which are adjusted to the required value of ? 1184 Ha,1184 Ha 298 = 8030 cal per g-atom [11 hr,1184-ha298 = 8245 cal per g-atom [2]

Jan 1, 1968

By H. Razavizadeh

The recovery of copper from oxide ores containing from 2% to 4.1% acid-soluble copper from the Sarcheshmeh mine in Kerman province of Iran was investigated by agitation leaching in sulfuric acid media. Quartz, as a major constituent, and malachite, as the major copper mineral, were identified in the ore by X-ray diffraction (XRD) and microscopic studies. A series of leaching experiments on the ore was performed over a concentration range of 10 to 20 g/L and temperatures from 15° to 50°C for a maximum of 3 hours. An initial high dissolution of copper was followed by a very slow reaction. By increasing acid concentration and temperature, the dissolution rate of copper was accelerated. However, by increasing acid concentration, the acid consumption of ores was also increased. Surface morphology of solid residues at various leaching times was examined with a scanning electron microscope (SEM). All SEM micrographs of the partially reacted particles displayed a needle structure. The kinetic studies showed that the malachite dissolution rate could be modeled in two stages. About 85% of the malachite dissolution occurred in Stage 1, while the remaining 15% occurred in Stage 2. The data obtained for the leaching kinetics indicate that the dissolution for Stage 1 was a diffusion-controlled reaction with an activation energy of about 20.6 kJ/mole, and the dissolution for the Stag 2 was a chemical-controlled reaction with an activation energy of about 87.6 kJ/mole.

Jan 1, 2008

By John Paul Gries

During World War II, when the curtailment of imports led to an unprecedented demand for domestically produced mica, beryl, and other pegmatitic minerals, the Bureau of Mines and the Geological Survey entered upon a program designed to expedite the production of these minerals from the Black Hills area of South Dakota. The program involved mapping, sampling and drilling many pegmatite dikes found in the southern portion of the area and beneficiation tests in the field and in the Bureau of Mines laboratories at Rapid. City, S. Dak., Rolla, Mo., Salt Lake City, Utah, and College Park, Md. This paper describes the mode of occurrence and the sampling and beneficiation tests on one dike, the Helen Beryl pegmatite, which was investigated as part of the general pegmatite study in South Dakota. Investigation of the Helen Beryl Pegmatite by the Bureau began in August 1943 and was terminated in April 1944. During this period the Bureau took a series of bulk samples from pits for beneficiation tests, drove an adit through the center of the dike to obtain feed for a bulk-sampling plant operation, and finally drilled a series of long holes to sample the deposit further. Geologists of the Federal Geological Survey mapped the deposit and the faces of all excavations and logged drill holes from sludge samples recovered from long-hole drilling.

Jan 1, 1949

By Shawna Munn, Jakub Hudler

This paper outlines the use of tunneling headwall softeyes for transit construction projects in the Greater Toronto Area (GTA) over the past decade. Due to spatial constraints, tunnel boring machines were used to construct the underground tunnels requiring the design of launch and exit shafts with headwall softeyes to facilitate tunneling operations. Variable ground conditions and shaft geometries lead to the development of innovative headwall and tunnel softeye design applications using fiber reinforced polymer (FRP) elements (beams, reinforcing bars, and tiebacks). This paper outlines the challenges and benefits associated with designing and constructing shafts using various systems. Lessons learned throughout design and construction of more than 20 structures over the past 10 years are outlined. The constructability challenges with using FRP and design performance are also discussed. For over a decade, the City of Toronto has been expanding its metropolitan transit network with a variety of new transit construction projects. Two recent projects in the Greater Toronto Area (GTA) for underground infrastructure include the Toronto York Spadina Subway Extension and the Eglinton Crosstown Light Rail Transit project. These add a total of 31 new stations and 18.6 km (11.5 miles) of underground transit (TTC 2017) (EllisDon 2016). Due to ground conditions and spatial constraints of existing surface infrastructure, these projects utilized tunnel boring machines (TBMs) to construct the underground tunnels requiring the design of various types of shafts and headwalls to facilitate underground tunneling operations. To allow for tunneling through the headwalls, these shafts were designed with “softeyes” - a section of the wall without metal reinforcement that allows the TBMs to tunnel through.

Jan 1, 2018

By S. Zhang, Z. Hua, D. Feng, X. Tong, X. Xie

The separation and beneficiation of low grade collophanite has long been a technical challenge in phosphorous production. It requires the joint efforts of process design, reagents optimisation and operational control. In this study, the statistical response surface method was applied for determining the optimum reagent dosing in the flocculate flotation of a low grade (18.59%) collophanite ore. The dosage of three reagents, including a pH regulator (Na2CO3), depressant (Na2SiO3) and flocculant (modified starch), were input parameters of the modelling design. Two quadratic mathematical models were derived for prediction of grade and recovery based on the statistical design. Statistical analysis of the experimental results validates the reliability of the models. Through further calculation, the optimum dosage of the three reagents were found to be 3,020g/t Na2CO3, 1,990g/t Na2SiO3 and 880g/t modified starch, with which a maximum recovery of 75.81% and P2O5 grade of 30.08% was obtained from flocculate flotation test. Keywords: Process optimisation, modelling, froth flotation, collophanite ore, response surface methodology

Jan 1, 2020

By William N. Matheson

The major consideration in any management and engineering decision is the economic evaluation of factors. The right decision is the best cost decision, provided of course that it is the safest. Changes, improvements, and advances in mining technology, as in any business, come about through the pressure of economics in combination with the inventiveness and engineering abilities of efficient mine operators. Without proper economic evaluation and an appreciation of profit and loss of an operation, advances in mining methods would come about at a slow pace, if at all.

Jan 4, 1959

By Winthrop F. Watts, Robert W. Waytulonis

During the 1980's. the Mine Safety and Health Administration (MSHA) proposed new regulations for the use of diesel equipment in underground coal mines, and the National Institute for Occupational Safety and Health (NIOSH) recommended that whole diesel exhaust be regarded as "a potential occupational carcinogen", and that reductions in exposure to exhaust pollutants would reduce excess risk. During the same time, the Bureau of Mines tested new emission control technology to minimize diesel emissions. The objectives of this paper are to discuss the major issues regarding diesel exhaust emissions. especially diesel particulate matter (DPM) , and to highlight emission controls that will be available. DPM is a potential health threat because it is respirable in size and is composed of nonvolatile carbon with adsorbed or condensed compounds. These compounds include potentially mutagenic or carcinogenic hydrocarbons such as polynuclear aromatic hydrocarbons and sulfates. DPM contributes to the degradation of air quality in mines with typical mean concentrations ranging from 0.2 to 1.0 mg/m3. In addition to adequate ventilation, control of DPM can be achieved by implemention of improved work practices, regularly scheduled engine maintenance, and emission controls.

Jan 1, 1991

By Tae-Hyun Kim, Kang-In Rhee, Jeong-Soo Sohn

The synthesis of Mn-Zn ferrite powder from spent zinc-carbon batteries was investigated using a series of physical treatment, sulfuric acid leaching and coprecipitation. Physical separation methods such as crushing, magnetic separation and sieving were applied to generate a non-magnetic material of 8- mesh undersize for subsequent leaching process. The 8-mesh undersize of the spent zinc-carbon batteries was assayed 23.9% Mn, 14.9% Zn, and 4% Fe. Metal extractions obtained in sulfuric acid leaching at the solid/liquid ratio of 1:10, 2 M H2SO4, and 60? with 6 vol.% H2O2 addition were 97.9% Mn, 98.0% Zn and 55.2% Fe. The leach liquor was finally adjusted to the Mn:Zn:Fe mole ratio of 1:1:4 suitable for producing MnZnFe4O8 ferrite powder by the addition of Mn, Zn and Fe sulfates followed by pH control. A co-precipitation test for Mn-Zn ferrite powder was performed at 80?, O2 gas flowing at 1.3 L/min. As a result of co-precipitation, Mn-Zn ferrite nanoparticles in 20 nm size with spinel structure were successfully synthesized. The saturation magnetizations of Mn-Zn ferrite powder (Mn1-xZnxFe2O4) were determined to be 39-91 emu/g with various zinc contents (X=0.2-0.8).

Jan 1, 2008

By Ettore Contestabile, Cameron Thomas

Implosive connectors such as XECONEXTn have been used extensively for joining electrical conductors. This implosive action of explosives has also been used in other forms of high-energy metal working with excellent results. However, the inherent blast energy of these units can cause environmental side effects (especially airblast) which may restrict their use around inhabited areas.

Jan 1, 1994

By J. Talja

Keywords: drying, steam drying, concentrates, copper, lead During the past twenty years steam drying has become a prominent technology for drying of non-ferrous metals concentrate. This is mainly because of its low energy consumption and very low emissions. The first applications of significant capacity were stationary steam dryers, which however, faced severe challenges in maintenance costs and availability. That technology was soon replaced by Kumera?s rotary steam drying technology, which has been the dominant technology in new dryer installations world-wide for the past ten years, ever since the first installation in Hamburg in 1999. There are ten Kumera steam dryers in operation today and five more to be commissioned during 2011. Practically every dryer is different owing to continuous development, new innovations and operational experience with continuous feedback from the operators. Most significant improvements relate to capacity increase with the Kumera steam-dryer family, new feeder systems at the wet end, a completely new design of the dry material discharge with increased availability, heating element design and material selection, and control systems. This paper discusses the modifications and improvements introduced which have enabled the Kumera steam dryer to become the global leader in new dryer installations.

Jan 1, 2011

By Dilip K. Paul, Charles H. Jacoby

The economic importance of salt domes has been recognized throughout the world, primarily because of oil and gas accumulations on their flanks, and to a lesser degree, for the value of their salt and potash. Recently they have become of value as hosts for cavities used to store hydrocarbons. In the near future we believe that their main value will be a source of geothermal energy. Although tremendous effort has been expended on the understanding of the geology and physical characteristics of the strata intruded by salt domes, relatively little energy has been exerted in the comprehension of the salt dome itself. Salt domes have long been recognized as a geological heat anomaly. With respect to other sedimentary rocks, salt is a good conductor of heat. Expressing values in 10-3cgs units, sedimentary rocks vary from 1.0 to 8.0; metamorphic rocks from 5.2 to 8.4 and igneous rocks from 3.1 to 9.8. Rock salt in its pure form has a thermal conductivity of 17. Thus a salt dome can be expected to act as a conduit bringing heat vertically from deep within the earth's crust.

Jan 5, 1974

By Rodrigo Cesar de Miranda

A importância de descrever o processo de beneficiamento por um modelo matemático tem sido apresentada por vários pesquisadores. O principal benefício é o controle e a otimização do processo dentro de uma situação industrial. O modelo seria capaz de prever determinada variável de controle do processo a partir de dados conhecidos. Assim, a simulação dinâmica representa um marco no campo da otimização de processos minerais. Essa tecnologia de simulação tem uma ampla aplicação no estudo de processos, o que permite a obtenção do seu conhecimento e domínio operacional. Além disso, possibilita melhores definições nas etapas de projeto, além de realizar uma análise de confiabilidade mais realista. O presente trabalho consiste em realizar uma análise de confiabilidade, através da simulação dinâmica, para entender como as paradas não-programadas influenciam a produção de uma planta de beneficiamento de ferro. Ainda, visa entender o desempenho fenomenológico dos equipamentos de acordo com a entrada de diferentes tipos de minérios e também como são suscetíveis a condições climáticas.

Aug 17, 2017

By Walid M. Abdellah, Soliman Abu Elatta A. Mahmoud, Hanaa A. Abu Khoziem

The high-grade Th-U-Y zone is one of the numerous mineralized zones found in the El Garra El Hamra hydrothermally altered syenites in southwestern Egypt. It is characterized by the thorium minerals thorite and thorogummite, which are closely associated with xenotime-(Y). This zone of mineralization is localized in the eastern part of the El Garra El Hamra hydrothermally altered syenites. This zone does not relate to the first phase of syenites that appeared on the surface but is linked to the other, hidden phase of the syenitic body. Additionally, the fluids responsible for the mineralization of this zone belong to the late-stage hydrothermal event as well as the fault action due to the fact that it had continued reactivations for a long period of time. The studied mineralized zone also contains ceriopyrochlore-(Ce),(Ce,Ca,)2 (Nb,Ta)2O6 (OH), fluorite (CaF2) and barite (BaSO4), which are found in considerable amounts, whereas apatite (Ca5(PO4)3F) and chromite (FeCr2O4) are rarely found together with Fe-oxi-hydroxides (hematite and goethite) with a minor amount of jarosite (KFe33+(OH)6(SO4)2). Finally, the main constituent mineral in the zone is the pseudomorph perthite in addition to quartz, which is found as deformed crystals. A technological sample was collected from this zone and was found to assay 4.62 weight percent thorium (Th), 0.37 weight percent uranium (U) and 3.12 weight percent rare earth elements (REEs). From the chemical and mineralogical composition of the studied technological sample, the leachabilities of Th, U and REEs were investigated using sulfuric acid (H2SO4) agitation leaching and pug leaching methods. The latter was found to be preferred under the conditions of 0.54 ton H2SO4 per ton of altered syenite at 110 °C for two hours.

By L. B. Berger, W. P. Yant

This paper presents evidence of the general occurrence of methane in a large number of the coal fields of the United States and substantiates the apparent unnecessary differences in the ventilation requirements and codes in the various states, as was brought to the attention of the Committee on Mine Ventilation of the American Institute of Mining and Metallurgical Engineers at its Pittsburgh meeting in October, 1925, by J. A. Garcia. The data in his report have been compiled from the files of the Gas Laboratory of the Pittsburgh Experiment Station of the Bureau of Mines and represent samples collected throughout the various states and submitted for analysis by its engineers, also by mine operators and State mining departments, since 1911. Several thousand analyses were available but most of them were rejected because they represented abnormal conditions, undefined place of sampling, special investigations, or duplications in the same mine. Only those samples were included which, without reasonable doubt, were ascertained to fall within three major classes, namely, main return, air splits, and face and rooms of live workings. In the case of air splits, and face and room samples, only the one which contained the highest percentage of methane found in a given mine was taken. OCCURHENCE OF METHANE IN COAL MINES OF THE UNITED STATES Obviously it is not feasible to present the detailed analytical data here and accordingly these data have been compiled into groups in a manner which it was thought would bring out clearly their significance. These are shown in Table 1 which includes the analyses of 310 samples of return air of approximately the same number of coal mines in 19 states. Because of changes in ownership and names the exact number could not be ascertained. The table also includes 337 samples from air splits and 263 from the face and rooms of some of the same mines represented by return air samples and from other mines in these states. A total of more than 400 mines are represented by Table 1.

Jan 1, 1927

By Axel Hultgren

IN ingots of silicon-killed carbon steel made without addition of - aluminum, transparent spherical or nearly spherical inclusions, up to about 0.15-mm diameter, are generally present. They may be glassy or crystallized, wholly or partially. In steels of high carbon contents they consist of silica,4,12 in steels of lower carbon contents arid, in consequence, higher oxygen contents, of iron-manganese-silicate with higher iron and manganese contents the lower the carbon content. Small silicate inclusions, about 0.01 mm or smaller, may occur, just as sulphide inclusions do, in portions that have been the last or nearly the last to freeze,10,12,17 this location being verified by primary etching.10 Hence, it may be concluded that they have separated from liquid steel that has become enriched in oxygen through segregation during freezing. Silicate inclusions with a diameter larger than about 0.02 mm appear, at least in ingots of moderate size, to be distributed at random in relation to the primary structure and therefore may be assumed to have existed as droplets in the liquid steel before freezing started at the point in question. The average size of such large inclusions has been found to increase toward the axis17 and their amount to increase from the top downward in the axial region .2,10 It has been assumed that this accumulation is a result of the droplets being brought down by the slowly settling metal crystals.2 It has been suggested that large silicate inclusions generally form,6 or may form," by coagulation of smaller ones, or by small drops being caught by larger ones during the rising of the latter.9 The occasional occurrence of a large inclusion surrounded by a swarm of small ones has been taken as a proof of this mechanism but, as suggested later, may be explained in another way. It has been pointed out that an inclusion droplet in the liquid steel may grow at the expense of an adjacent one, which implies diffusion of soluble inclusion-forming elements in the liquid steel.15 Further, it has been pointed out that, on cooling in ladle or mold, the metal-silicate equilibrium is displaced in the direction of separation of silicate. Thus inclusions may grow in size and amount.2,3,8,12,13,17,19,20 The exposure of the liquid steel to the oxygen of the air during tapping and pouring, and the consequent reaction, has been mentioned as a source of the formation of inclusions19,20 but this possibility has not received particular attention. Further, the admixture of furnace slag during tapping' or of refractory material from various sources1,20 has been considered. The inclusions due to the latter may be recognized, however, through their resistance to hydrofluoric acid, imparted by the alumina content. Silicate inclusions, are often referred to as. the natural and inevitable product of reaction on adding silicon or silicon

Jan 1, 1948

By Eugenio Thiers

El presente trabajo señala la utilización de carbones andinos en la industria metalúrgica. Los países de la región andina como Perú, Bolivia y Ecuador contienen carbones coquizontes de buenas características, pero con bajo poder aglutinante. Por ello, se busca ampliar las posibilidades de su uso a través de la producción de metales. La producción se distingue en dos alternativas: primaria y secundaria. La primera incluye extracción minera, procesos de concentración mecánica, fundición y refinación, mientras que la segunda, se basa en la recuperación de materias primas a partir de la chatarra. Así también su uso principal de extiende a la siderurgia y afines.

Sep 1, 1985