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By Xinli Wang, Matthew Andriese, Jiann-Yang Hwang, Zhiwei Peng, Byoung-Gon Kim

"The microwave dielectric properties of silicon dioxide at frequencies of 915 and 2450 MHz were characterized in the temperature range of 24 to approximately 1000 °C using the cavity perturbation technique. It is shown that the relative dielectric constant of silicon dioxide at both frequencies remains almost unchanged below 500 °C, above which there is a slight increase of 2%. The relative dielectric loss factor of silicon dioxide exhibits a strong temperature dependence above 500 °C and increases by approximately 7 and 5 times at 915 and 2450 MHz, respectively. The substantial increase in the relative dielectric loss factor is mainly attributed to the enhanced dielectric polarization and accelerated electrical transport in silicon dioxide at elevated temperatures.IntroductionSilicon dioxide (Si02) is usually considered a microwave transparent material due to its poor absorption capability at room temperature [1]. This characteristic has led to various applications of silicon dioxide in microwave processing of materials and communication. For instance, Si02 has been used to produce sample holders for microwave heating and substrates for electronic devices [2,3]. These applications generally require the material to withstand high temperatures under microwave irradiation. This indicates that microwave absorption capabilities of silicon dioxide at elevated temperatures are also important for its utilization.The microwave absorption capability of Si02 can be determined based on dielectric characterization (permittivity measurement) of the material at commonly used microwave frequencies, 915 and 2450 MHz, in a broad temperature range. To date, however, no detailed work on the dielectric properties (permittivity) of silicon dioxide at high temperatures has been reported. The present work is aimed to study the dielectric properties of silicon dioxide from room temperature to approximately 1000 °C at 915 and 2450 MHz. The results show that the permittivity of silicon dioxide has a strong temperature dependence above 500 °C, suggesting a substantial increase in its microwave absorption capability."

Jan 1, 2013

By Adam Gesing, Paul Marchwica, Jerry Sokolowski, Sharon Lackie

"Often referred to as SEM-EDX, energy-dispersive spectroscopic analysis of characteristic fluorescence x-ray is a standard technique for semi-quantitative elemental composition analysis in scanning electron microscopy. It is quick and extremely useful for identification of phases in the sample microstructure, as long as the constituents are significantly larger than the probe volume from which the fluorescence x-rays originate. The probe volume ranges from a few to several microns, depending on the electron beam spot size and the acceleration voltage. We report on a new variant of an EDX technique developed to overcome this limitation and allow quantitative elemental analysis of smaller phase constituents, down to a size of several nanometers. This variant involves the calculation of compositions of individual phases from multiple analyses of areas containing phases of interest. This significantly increases the usefulness of EDX for quantitative analysis of new nano-structured materials.IntroductionIn any elemental micro-analytical method, the sample material is illuminated by a probe beam that excites an interaction volume of a sample to emit a characteristic signal. This signal in turn interacts with the sample material through absorption and fluorescence mechanisms before a portion of it is collected by a suitable detector and analyzed for elemental composition. The spatial resolution of the method depends on the minimum interaction volume between the probe beam and the sample material.Laser light beams can be tightly focused to a spot size limited by the photon wavelength and can be used to sample the surface of any material. In micro-LIBS (laser-induced plasma spectroscopy) a focused laser beam ablates and vaporizes a small volume of material from the sample surface, creating a plasma spark. Spectral analysis of the light emission from the plasma spark allows the semi-quantitative determination of the elemental composition of the material removed from the sample surface. The smallest reproducible craters achieved are ~ 3mm in diameter and a few nanometers in depth. [l]Particle probe beams of ions or electrons can be focused to a diameter of a few nanometers at the point of impact on the sample. Ions sputter the sample atoms from the point of impact, and the sputtered ionized material is analyzed by mass spectroscopy in a secondary ion mass spectrometer (SIMS). [2] This gives SIMS resolution in a nanometer range. SIMS equipment, however, is expensive and not readily available."

Jan 1, 2013

By Yuanbo Zhang, Helei Zhang, Heng Yu, Guanghui Li, Zhengwei Yu, Tao Jiang

"Composite agglomeration process (CAP) is an innovative method for preparing blast furnace burden. For CAP, the classified raw materials of pelletizing feeds and matrix feeds are mixed, charged and sintered. The characteristics of these two kinds of feeds obviously affect the permeability of per-ignition bed, as well as the sinter productivity and quality. In this study, the Ergun equation is proposed to predict the pressure drop of CAP bed using the particle size distribution. The calculation process indicates that the Dv and the Em are the two tuning parameters. The results show that there is a gap between the calculated values by Ergun equation and the measured results by pressure drop testing facility. Eliminated this error by modified the Ergun equation and then validated it through experimental studies using simulated CAP mix and test facility. Therefore, the modified Ergun equation can be used to predict the permeability of CAP bed.IntroductionThe sintering process is one of predominant agglomeration processes for preparing ironmaking burden from iron-bearing materials. Sinter accounts for 70-80% of the blast furnace burden in China and the continuous improvement of sinter quality provides a guarantee to anterograde production of blast furnace. Sinter productivity and quality are strongly related to the permeability of the bed during sintering, which is dependent on the structure of the bed before ignition in the early stage [l]. The size distribution, the shape of granules and the bed voidage are the primary affecting factors to pre-ignition permeability."

Jan 1, 2013

By Peter C. Hayes

"The high temperature reduction of solids through the use of reactive gas atmospheres has application in a wide range of industrially important processes. Whilst significant advances have been made in understanding and describing these processes, some key aspects of the chemical reactions and reaction mechanisms operating in these systems, for example, the transformation from metal oxide to metal, remain poorly understood. A number of different product morphologies have been identified in these reaction systems and the reaction rates have been shown to be critically dependent on the product structure.Theoretical examination of the elementary process steps taking place in the region of the gas/metal/metal oxide interface, combined with electron microscope studies of the resultant product microstructures, have enabled the key process and material variables responsible for the development of the various product morphologies to be identified. By considering i) established criteria for the stability of moving interfaces in a thermodynamic potential gradient, ii) the relative rates of chemical reactions on the oxide and metal surfaces, and iii) key process phenomena and physico-chemical properties of the solid phases, the mechanisms and conditions for the formation of various product morphologies are identified. Interestingly the analysis points to direct analogies between these phase transformations and, the phenomena and microstructures observed in metal solidification, and the potential to develop generic models of these fluid/solid reaction systems."

Jan 1, 2013

By Xicai Gao

With the intensification and expansion of deep coal mining, the surrounding rock stress environment becomes further deteriorated because of the complicated geological environment and powerful mining effect, so the major deformation of roadway appeared frequently. The proportions of floor heave are increasing and , the most serious problem is the floor heave of preparatory workings. The coal seam of Binchang coal area in Shaanxi province is at a depth of 621.6 ~ 817.0 m, the average thickness of the coal seam is 25 m, and the overburden and coal measure strata are the main regional aquifers and are highly permeable. The properties of water-weakening are obvious in the floor strata. The main preparatory workings or chambers were driven in the coal seam. The severe floor heave of the water chamber appeared during early mining and the amount was 180 ~ 910mm, and seriously affected the normal installation and use of the water chamber. Theoretical study and numerical simulation as well as the in-situ measurements were carried out to investigate the deformation and failure characteristic of the surrounding rock with non-support in the floor and the main reasons which caused the floor heave were determined. A new combined support technology was proposed which consists of overcutting, grouting, backfilling and invertedarch and bolt-grouting. The field monitoring showed that the cumulative convergence of the water chamber was 20mm, the maximum convergence speed is 1.2 ~ 2mm/d, the accumulative convergence of two ribs was 36mm and the maximum convergence speed is 2mm/d. The combined support technology will enhance the support intensity between the roof and floor, the two sides of the entry and improve the loading capacity of the floor effectively and the floor heave can be controlled effectively.

Jan 1, 2013

By Anthony T. Iannacchione

The Solar No. 7 and Solar No. 10 mines were designed to prevent mine waters from directly discharging to the surface. In January of 2004, a discharge occurred as the Solar No. 7 mine was in its final stage of flooding through a barrier averaging 456-ft in width over a 1,600-ft length (No. 1). Another barrier (No. 2) was designed to protect four municipal water wells operating 1,800- ft away and producing from within or slightly below the Upper Kittanning coalbed from the adjacent Solar No. 7 and No. 10 mine pools. These two barriers were selected for this study because of varied mine layouts, mining methods, and geology factors affecting their performance. Analysis was aided by the collection and georeferencing of 6-month mining maps from the Pennsylvania Department of Environmental Protection (PA DEP). A structure contour map of the Upper Kittanning coalbed was constructed from mine map elevation points. These data and 2-ft surface contour maps were used to measure the precise location of the coal outcrop. The actual discharge point was as little as 425-ft away from a thinpillar section and 475-ft away from a pillar recovery section. The discharge point was found to be located slightly above the coal, indicating that the drainage path was at least partially through the strata directly above the Upper Kittanning coalbed. Hydraulic conductivities and potential discharge pathways are analyzed and discussed. The possible factors influencing the performance of the down-dip barriers at Solar No. 7 and Solar No. 10 are: a) the width of the barrier, b) the applied hydraulic gradient, c) the type of mining adjacent to the barrier, d) the overburden, e) the pattern and characteristics of fractures, and f) the quality of waters contained within the mine pools. This study, part of a larger effort funded by the Appalachian Research Initiative for Environmental Sciences (ARIES), is tasked to determine the key factors responsible for the successful design of down-dip coal barriers.

Jan 1, 2013

By C. J. Tonkin

Compressed air is widely used on South African gold mines. However, due to recent and proposed future electricity tariff increases it is quickly becoming too expensive to produce and use. Boxfront chute systems at ore passes were focused on during this study, and a number of alternative power sources were examined. After comparing primarily costs, and secondarily safety and practicality, of a number of systems based on water and hydraulic oil, a system making use of either air or water was determined to be the most cost effective. A payback time of 8 years was calculated, which will be significantly less taking into account the avoidance of failures due to electricity and water shortages, which would not affect this system due to its ability to swap between either air or water. It was recommended that this system be installed at all boxfront chutes as soon as possible so that the company can begin to benefit from the cost savings.

Jan 1, 2013

By J. Labuschagne

There are a number of factors that contribute to the profitability of a mine and its associated concentrator. Chief among these is the time taken from the first hoist of material from underground to the first batch of concentrate shipped. The main aim of this project was to integrate the mining model with a concentrator production schedule to minimize the time it would take to produce concentrate (without the concentrator having to stop because of a lack of feed material) in the most capital-effective manner. A secondary goal was to ensure detailed stockpiling requirements, as the concentrator is in an area where 'visual pollution' is to be avoided. To achieve these two goals a dynamic stockpile model was created by utilizing the mine production schedule and breaking it down to a daily production figure. Four different concentrator development models were then proposed. The difference between the mine production and concentrator consumption was integrated over the life of the mine to provide the accumulated stockpile tonnages for both Merensky and UG2 ore. To prevent a situation where the concentrator was operational without any feed, the stockpile levels were never allowed to fall below zero. When a development option was selected, the standard metallurgical performance calculations were used to derive a concentrate production schedule, which was used as a basis for commercial negotiations for the sale of concentrate.

Jan 1, 2013

By Seyed Mahdi Abbasi, Adel Sheikhhosseini

"This research was conducted to study the changes of microstructure, chemical composition and mechanical properties ofIN718 superalloy after adding aluminum to the ESR process slag. The experiments were performed in VIM and ESR furnaces. The results showed adding 1.5 percent aluminum to the slag increase lave phase in the IN718 samples from 0.34 percent in the base sample to 3.0 percent. It also indicated that the more increase of aluminum in slag cause decrease in the aluminum absorb yield in the superalloy.it is observed that increasing aluminum from 0.7 to 1.1 and then to 1.5 percent caused a decrease of absorb from 91.4 to 76.3 and 74.6 percent respectively due to increasing of aluminum oxidation. According to the results, tensile strength increased and ductility declined in the IN718 samples mainly because of rising the amount of y' volume fraction.IntroductionIN718 superalloy is an iron-nickel base superalloy with constant mechanical properties at medium at high temperatures. For the past seven years a considerable amount of time and effort has been expended by both suppliers and users in the study of Alloy 718 [ 1]. The interest in this material stems not only from the interesting metallurgy associated with the alloy, but with the large usage of the material in numerous applications In fact many people believe that the projected use of this alloy increase significantly over the next several years, The large use of Alloy 718 is the result of its performance in respect to high strength, good ductility, good repair weld ability and from its versatility of being supplied in various product forms. This superalloy is used in wide ranges of industries such as aerospace and gas turbines [2]. In the past more than 20 years many researchers did a lot of work to improve the structure stability of IN718 at high temperatures and intended to develop a new 718 type alloy to be used beyond 650 °C. One of the methods is to control and phase precipitation behavior by means of adjustment of Al, Ti and Nb contents. The other idea is to strengthen the matrix by altering the content of solid solution elements such as W and Co. The adjustment of these alloying elements can change phase precipitation behavior [3]. If detailed information dealing with phase precipitation behavior can be obtained before experimental work for alloy development, a lot of time can be saved and the development cost can also be reduced. In recent years, computer modeling based on experimental data plays an increasing role in alloy design and development. Adding Al to the Iron and Nickel increas the strength of superalloy by formation of y phase and subsequence formation of n phase. Ti in IN718 superalloy also helps the formation of MC carbides and gamma prime phase. Increasing Al/Ti and (Al + Ti)/Nb will lead to form finer particles of y'. More uniform distribution of the precipitates and enhancing stability of y' in IN718 superalloy [ 4]. Adding Al to slag of ESR process can reduce the oxide inclusions because of the strong tendency of Al to oxidation. In addition, tensile properties of IN718 superalloy improve. The most significant inclusions in IN718 superalloy are Alz03 and TiN that were found in agglomerate forms. Thermodynamic calculation results indicate that the effect of increasing Al shows a strong increase in solvus while phase solvus shows mildly decrease when Al level is less than 2%, after that it dramatically decreases [ 5]. Laves phase precipitation and the appearance of phase are occurred when Al content reaches 2%. In fact, when Al content is beyond 1.5%, phase has already precipitated in a considerable scale. Shows the fraction of increases greatly while the fraction of phase decreases remarkably with the increment of Al content. Based on thermodynamic theory, if these particles were not existed in the melt during cooling agglomeration would not accrue and the superalloy will be cleaned By adding Aluminum to the slag, the metal reacts with oxyge"

Jan 1, 2013

By Phil Thwaites

"The mining industry uses many types of mineral and metallurgical plants to produce saleable product from ore mined. Plant design history has left current operations with a mixture of manual operation and various forms of automated process controls. Consequently, we typically see high variability in the continuous operations together with a shortfall in the attainment of full capacity, or higher utilization of consumables.At a level of best practice, “Operational Performance Excellence” focuses on process control, using automation and control systems to deliver process optimization. This more sophisticated delivery is a great deal more difficult than the first stage of equipment selection / installation. It includes the appropriate selection of the right instrumentation, control system, key process knowledge, individuals with a solid control engineering background/experience, and the essential backing/ support of the operations management team together leading to higher value delivery. Robust solutions can be realized, considerably minimizing process variation, thus leading to process optimization. This approach results in an easier, efficient and safer process while providing considerable returns for the plant owners.How variable are your processes, and do you maintain optimized process performance with dedicated resources, modern instrumentation, ‘best practice’ control systems and performance monitoring tools? In this lecture, these questions and their possible answers are discussed.357"

Jan 1, 2013

By Tianzu Yang, Weifeng Liu, Lin Chen, Deyu Wang

"Due to the gradual exhaustion of easily extractive gold ores, it is vital to make efficient use of refractory gold ores which hold 30% gold storage of the world. However, the disadvantage of current processing technologies for refractory gold ores consists of severe pollution, low gold extraction ratio, high investment, etc, thus great research interests were attracted during recent years. This article provides an overview of the distribution and categories of the refractory gold ores in the world. The state of art in processing refractory gold ores by pyrometallurgy, hydrometallurgy and biometallurgy techniques and their industrial applications are highlighted. Potential environmental conservative techniques for efficient gold extraction are also reviewed.IntroductionResources of Refractory Gold OresAs easily extractive gold ores are going to be exhausted with the large scale mining nowadays, refractory gold ores are becoming more and more important. Gold in the refractory gold ore cannot be fully extracted using conventional method (cyanidation) even with fine grinding. The amount of gold in the refractory gold ores is about 1500~2000t in China, which occupies 30~40% of the total gold storage [1]. Therefore, it is vital to make efficient use of refractory gold ores."

Jan 1, 2013

By Vincent Tirolo

The proposed Second Avenue Subway is a new two-track subway line running from 125th Street and Park Avenue at the north, east along 125th Street to Second Avenue and south along Second Avenue to the Financial District in lower Manhattan, NY with 16 new stations and 13.6 km (8.5 miles) of track. The project has been broken into four construction phases. The initial Phase 1 operating segment includes three new stations (96th, 86th and 72nd Street stations) with a connection to the existing Broadway line at the 63rd Street Station at Lexington Avenue. Rehabilitation of the 63rd Street Station is also included in the scope of Phase 1. Subsequent phases extend service north and west to 125th Street (Phase 2), south to Houston Street (Phase 3) and finally to Hanover Square (Phase 4). The DMJM Harris/Arup Joint Venture (DHAJV) prepared the Contract Documents MTA for Phase 1. Parsons Brinckerhoff is providing the MTA with construction inspection services for Contract C-26002. In April 2007, NYCT awarded first Phase 1 for $337 million to S3 Tunnel Constructors, a tri-venture comprised of Skanska USA Civil, Schiavone and Shea. Contract C26002 is for the construction of the tunnel boring ma-chine (TBM) launch box and the mining of the TBM tunnels from 92nd Street to 63rd Street. The major part of the contract is to construct a shaft, commonly referred to as the launch box, from East 92nd Street to East 95th Street having dimensions of 244-m- (800-ft-) long by 18.9-m- (62-ft-) wide and a depth of 19.8 m (65 ft), including more than 91,000 m3 (119,000 cu yd) of soil and rock contained within its walls. The launch box will ultimately become the southern half of the 96th Street Station. The focus here is geological conditions at the launch box and existing structures along the launch box. These geologic conditions and existing structures had a major influence on the selection and design of the support of excavation system (SOE), the SOE bracing system, construction staging, the ground movements, dewatering and other challenges of constructing the launch box (Fig. 1).

Jan 1, 2013

By Robert B. Bittner

The Sutong Bridge across the lower Yangtze River in China will have, when completed, the longest span (1,088 m) and the highest towers (306 m) of any cable stayed span in the world. The foundations for this record setting span will also be record setting. They are located in water depths exceeding 30 m with maximum flows exceeding 3 m/sec. The soil at the site of the main pylons consists of layers of silty sands and silty clays extending to bed rock at 270 m below river elevation. This paper describes the innovative methods used by the team of foundation designers and constructors to support this record setting bridge at this very challenging site. This paper covers three specific topics related to the foundations of the Sutong Bridge: ? Design and construction of the 131 drilled shaft (2.8/2.5 m diameter and 114/117 m long) under each of the two main pylons, including the post-grouting of all drilled shaft tips. ? Design and construction of the scour protection for the two main pylons, ? Construction methods used to construct the waterline pile caps (113.8 m by 48.1 m by 13.3 m deep) under each pylon.

Jan 1, 2013

By Dakota D. Faulkner

Cable bolts anchored with traditional two component polyester resin cartridges have successfully supported difficult roof conditions in underground mines. Resin cartridges provide a costeffective cable bolt anchoring system with consistent anchorage performance characteristics when properly installed. The most commonly used cable bolts in the U.S. mining industry are 270 ksi (1,862 MPa), 0.7 and 0.6 inch (18 and 15 mm), seven-strand smooth cable with resin mixing bulbs (also known as bird cages), and 40- and 30-ton nominal capacity, respectively. However, there are other types of cable bolt anchoring systems aside from bird cages. Recently, many questions have been raised regarding the anchorage characteristics of various types of cable bolts. Keystone Mining Services, LLC (KMS), the affiliated engineering company of Jennmar Corporation, conducted a variety of controlled tests developed to closely model actual underground installations. These tests compared the performance of three commonly used cable bolt varieties, including plain, bird caged and indented seven-strand cable. Details of the laboratory testing and comparative analysis of the results are provided.

Jan 1, 2013

By Qingchun Yu, Bin Yang, Yong Deng, Heng Xiong, Fei Wang, Minxiu Chen

"Metal aluminum produced by non-electrolysis process received much attention due to its lower energy consumption. In this paper, carbothermic reduction and carbothermic-chlorination of alumina in normal pressure and vacuum were studied. The products were examined by means of XRD, EDS and SEM. During the carbothermic reduction process using carbon reductant in normal pressure, no metal aluminum was found. However, when coal was used as reductant, a mixture containing metallic aluminum, A14C3, and silicon was obtained, but metallic aluminum couldn't be separated from the mixture. During the carbothermic-chlorination process in vacuum, Al404C and Al4C3 were produced by the reaction between alumina and carbon, and Al Ch gas reacted with Al404C and Al4C3 to produce Al Cl gas. Metallic aluminum was produced due to the disproportionation of A!Cl gas and condensed on the collecting plate. Meanwhile, the initial temperature of carbothermic reduction of alumina reduced in vacuum compared with that in normal pressure.IntroductionIndustrial production of primary aluminum is carried out in alumina cell by the so-called Hall- Heroult process, necessitating the use of very high currents of low voltage. The alumina from which metallic aluminum is gained must be chemically pure, otherwise impure metal results. The main drawbacks of the electrolytic production are its very high energy consumption, the release ofperfluorocarbons, and the high specific C02 emissions [1]. During the past years, there were a lot of attempts to produce metallic aluminum by carbothermic reduction of A1203 [2, 3]. Cox [4] determined the vapor pressure over the A1203-C system and performed X-ray diffraction analysis of condensed products. It was demonstrated that an increase in the carbon content in the system leaded to the sequence of transitions: A1203~Al404C~A1zoc~A14C3 ~AI [5]. In any carbothermic reduction process for aluminum, extremely high temperatures (2000 °C ) were required [6]. In spite of considerable effort, the carbothermic reduction of alumina to aluminum remains a formidable technical challenge, due to the high temperatures required, and to the formation of aluminum carbide and oxycarbide byproducts [7]."

Jan 1, 2013

By W. van der Merwe

ABSTRACT With the gold industry processing more complex ores, the online measurement and control of cyanide addition to the gold leaching circuit has become more critical. This paper compares the two commonly employed ‘free’ cyanide online analysis methods (amperometric and potentiometric endpoint silver nitrate titration) with the rhodanine endpoint silver nitrate titration and ion selective electrode methods common at site laboratories. Measurement differences between these methods are presented and discussed for cyanide solutions containing copper and zinc with varying cyanide to metal ion ratios. The resulting cyanide available to leach gold is also compared using these measurement techniques.

Jan 1, 2013

By B. G. Cousins, B. O’Rourke, C. Spence

"Some non-flotation chemistries are added to flotation circuits directly and indirectly to control issues such as scaling and dust. Since the dosage levels are generally not very large, a standard laboratory float test may not be able to determine the effect a specific chemical has on the productivity of the flotation circuit. Hudbay and Ashland Water Technologies developed a laboratory testing protocol that uses kinetic float studies to test the effect of normal to extreme doses of antiscalant and dust chemistries (5 ppm to 500 ppm). Laboratory results indicate that this protocol helps to predict the potential interference that a particular chemistry will have on the flotation circuit.INTRODUCTIONFrom a chemical perspective, flotation is a very complex system involving more than the reagents used for flotation. Along with collectors, frothers, modifiers, suppressants and activators, there can be antiscalants for water treatment, dust suppressants used in the mining process, residual flocculants from recycled thickener overflows, grinding aids, and many other types of chemicals that are added upstream of a flotation circuit. Although these other chemicals are usually used at very low doses, it is important to know if they affect the flotation process detrimentally in the event of a spill or a build up from recycled water.Laboratory flotation testing of these chemicals characterizes their effects, but testing at expected doses in the float can mask the effects of the chemicals in the plant. Also, simple tests that do not measure the kinetics of flotation do not reveal the effects the other chemicals have on the flotation circuit. Thus, a new flotation protocol was needed to expose the full effects of chemical additives and to assist in choosing the chemical with the lowest potential for a negative effect.FLOTATION KINETICSMeasuring recovery kinetics in a laboratory flotation cell is a well-established procedure: analyzing concentrates taken in a timed sequence to determine the recovery rate of individual cells in a flotation circuit. The recovery from the early flotation cells are a true measurement of how well a flotation chemical is performing. The principles of kinetics can be mathematically determined by the following functions (Houston, 2006):"

Jan 1, 2013

By D. Van Tonder, C. Edwards

ABSTRACT Solvent extraction is used in many acid leach uranium circuits to upgrade and purify the uranium-bearing solution prior to final product precipitation. A number of strip options are available to recover the uranium from the loaded organic. This paper compares seven of these options on the basis of typical capital and operating costs for the solvent extraction circuit and downstream uranium processing and also considers other related issues. The aim is to provide an objective comparative assessment of these options that could be used as a qualitative guide in process selection or improvement.

Jan 1, 2013

By Corry Goumans, Dan Agostino

Photo 1. Demolition work on the Pitt River Bridge. The drill crew is using the 3800 Gardner Denver Air Track to drill the holes on the Bridge turning dolphin. The barge in the background is used for support.

Jan 1, 2013

Interstate 70 running into the mountains west of Denver, CO is the main access to the state?s numerous ski areas and other tourist attractions. As such, the highway is a vital part of Colorado?s economy. Due to the mountainous terrain in which it winds, I-70 is limited to two lanes in either direction. And, during the past few decades, the volume of traffic has increased to the point where motorists encounter major delays, particularly on Friday evenings and Saturday mornings heading west from Denver, and then again on Sunday evenings heading east. In the past, those delays occurred mostly during the ski season. However, many of the mountain towns have been successful in turning their resorts into year-round vacation destinations. A good move economically, but the pressure added to I-70 has caused even greater traffic delays, sometimes to the point where some Front Range residents avoid trips to the mountains.

Jan 1, 2013