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By Charles I. Richman

Aquispirillum magnetotacticum (AM) is gram-negative hetrotrophic bacteria that belongs to a class ,of magnetotactic bacteria that have an ecological niche in marine marches and fresh water swamp sediments. Thiobacillus Ferrooxidans (TF) is a Gram-negative, acidophillic chemoliths that may have similar chemical conditions within the cytoplasmic membrane as Aquaspirillum M. to support growth of Magnetosomes. Magnetosomes are cellular bodies that accumulate under slightly aerobic conditions. Magnetotactic motion occurs in an external magnetic field and depends on the medium viscosity. The Atomic Force Microscope equipped with a magnetic tip shows the presence of Magnetosomes in these bacteria strains. The size, shape of magnetosomes in AM and TF strains are characterized.

Jan 1, 1998

By R. M. Cunningham

Asarco operates one of the largest individual copper electrolytic refineries in the world at Amarillo, Texas. The feed for this refinery is a mixture of anodes produced at Asarco smelters and copper purchased t?om a number of primary and secondary sources. The variation in feed makes it imperative that the refinery practices state-of-the-art quality control to minimize the effects'of unwanted impurities in the electrolytic refining process. In late 1993, a plant designed to sigru6cantly reduce the antimony and bismuth levels in the electrolyte was commissioned. The purification plant uses ion exchange technology in conjunction with a novel strippiing system developed by Zeneca Specialties (U.K.). The strippiing system permits the recycling of the eluant and thus avoids the extremely high costs of stripping with conventional reagents. In addition, the environmental impact of treating the eluant for recovery of antimony and bismuth is minimized. This paper outlines the development of the technology and, in particular, describes the operational practices and improvements at Amarillo since the commissioning of the plant.

Jan 1, 1997

By Louis J. Cabri

The ion microprobe (dynamic SIMS technique) is a very sensitive instrument for the quantitative determination of trace concentrations of precious metals (often at the ppb level) occurring in common sulfide minerals, either chemically-bound or as discrete particles too small for resolution by SEM. The technique involves sputtering a 250 x 250 Jim area of the grains to a depth of about one ILm and analysing the secondary ions emitted from a circular central region in the sputter crater with a 62.5 I'm diameter. The combination of quantitative mineral-specific sub-ppm analyses together with depth-profiling and the ability to produce secondary ion maps of trace precious metals makes this a very powerful technique in quantifying the precious metal distribution in refractory and other sulfide ores and process products. The technique is particularly well-established for analysis of gold-and platinum-bearing ores and process products.

Jan 1, 1996

By Catherine Cai

A granular sorbent, prepared by gel-coating polyethyleneimine (PEI) on high surface area silica followed by crosslinking with a low-molecular weight diepoxide, has significantly higher uranium capacity, greater salt tolerance, and faster kinetics than the commercial resin Dowex 21K. Though having lower U(VI)/Fe(III) selectivity than Dowex 21K, the gel-coated PEI affords much higher sorptions of both U(VI) and Fe(III) and also their separation by selective stripping with acid.

Jan 1, 1999

By Amy Nelson

In the electrolytic production of zinc, cobalt is removed from the zinc electrolyte by cementation with zinc dust prior to electrowinning. Although the thermodynamics for this reaction are favourable, kinetic barriers to cobalt reduction render the method almost useless in practice unless activators such as copper and antimony or arsenic are added. There is a large body of work studying the effect of these additives, yet the mechanism by which they act is still poorly understood. Even when the target conditions are met, zinc dust consumption is excessively high: satisfactory operation requires up to 300 times the stoichiometric amount of zinc dust. The objective of this work is three-fold: (1) to examine the effects of activators and elucidate the characteristics that make a good activator; (2) to identify new additives that could lead to a more efficient purification process; and (3) to test the new additives with synthetic and real electrolyte solutions. The present paper gives a status report on this project.

Jan 1, 1998

By Robert Matusewicz

Ausmelt Technology has been applied to the recycling of spent pot liner (SPL) generated from primary alnminum production. The process is centered on the Ausmelt furnace, in which the SPL is converted under high temperature, oxidizing conditions to an HF containing gas stream and inert slag. fluorine is recovered from the SPL as HF gas and is concentrated and used to manufacture AIF) for recycle to the aluminum smelters. Approximately 87% of the fluorine can be recovered and converted to AIF), with the remainder being effectively tied up in the by product slag. Cost projections show that the recycling process will be competitive with other processes for SPL. The production and recycling of AIF) provides available credit that significantly offsets the operating cost of the facility. Ausmelt Technology for recycling of SPL is currently being marketed in North America by Ausmelt Technology Corporation in Denver, Colorado, and in the rest of the world by Ausmelt Limited of Dandenong, Australia.

Jan 1, 1996

By K. Ono

A new process for extraction of titanium metal from its oxide is demonstrated. In this process, row material to be reduced is titanium oxide synthesized from ilmenite. The reducing agent is the Ca+CaCI2 two-phase mixture. TItanium is elaborated in the medium consisted of liquid Ca, Caq and solid TI02 at the temperature range 1200 to l300K by means of mixing mechanically the ingredients in the reactor into a smooth paste. Fluidity of the feed which enables continuous scheme depends on the CaCl2 content. The oxygen level of the reduced titanium is the range 500 to 1000 mass ppm varying with the operational conditions. The Ca+CaCI2 reducing agent is taken out from the electrolysis of CaC12 at 11401(, and this CaCl2 is produced by aqueous chemistry conversion using Cl2 gas recycled from the electrolysis.

Jan 1, 2001

By Lichao Ding, Chunhua Liu, Yunnen Chen

"In this paper the simulated acid magenta dye discoloring the reaction process was researched. The results showed that it attained highest decolorization efficiency for acidic magenta simulation dye wastewater when pH 9 and reaction time 10 min. With the initial dye wastewater concentration increased, the decolored rate decreased. The decolored rate in general kept a tendency to increase with the temperature increased. Kinetics researches showed that when pH 9, reaction temperature 20 and 35 ?, the decoloring reaction process for the dyes accorded with the First-order dynamic equation. The decoloring reaction rate constant was influenced by initial concentration of dye wastewater and temperature.1. IntroductionIn China, textile printing and dyeing industry is one of industrial departments which using more water and discharging more wastewater. There is about 7 billion tons of waste water discharge each year, of which 80% from the process of printing and dyeing. Being complex ingredients, high chroma, more toxic substances and severe environment pollution, the treatment of printing and dyeing wastewater becomes problem urgent to be resolved. The traditional treatment methods such as adsorption [1], coagulation [2], biochemical method [3,4], which has advantages of simple equipment, simple operation and mature process, but they can cause waste accumulation and secondary pollution [5,6].Magenta is a kind of organic compounds, which classified into acid and alkaline magenta. Considering the advantages of simple operation, low cost, simple experiment equipment and friendly to environment, acid magenta dyes wastewater was chose as object in this paper. Some parameters such as pH, contact time, temperature and the initial concentration on of simulative acid magenta dyes wastewater were studied."

Jan 1, 2012

By Andy Judge

"In traditional Permanent Magnet Machines, such as electric motors and generators, power is transmitted by magnetic flux passing through an air gap, which has a very low magnetic permeability, limiting performance. However, reducing the air gap through traditional means carries risks in manufacturing, with tight tolerances and associated costs, and reliability, with thermal and dynamic effects requiring adequate clearance. Using a magnetically permeable, high thermal conductivity material has the potential to improve magnetic performance, while at the same time offering performance advantages in heat transfer.Ferrofluids can be used to improve permeability in the rotor I stator gap. However, there are several tradeoffs in this approach. Fluid immersion comes with an increase in fluid friction loss compared to the windage losses of a traditional system. Isolating the rotating components from the ferrofluid can offset this effect. Also, while the magnetic effect can be positive for gap permeability, leakage flux can increase, and saturation can limit gains. These effects must be taken into account for a system optimized for ferrofluid immersion.IntroductionPermanent Magnet Machines (PMM's) convert electrical energy to mechanical energy in motor applications, or, for generator applications, convert mechanical energy to electrical energy through means of passing alternately polarized magnets past electrical coils. Looking at a simplified version of a PMM, where Rx is magnetic reluctance and <l>x is magnetic flux, we have the circuit shown in Figure 1."

Jan 1, 2013

The generation of acid mine water is? due to the oxidation and weathering of sulfide bearing tailings and overburdens. Ferrite precipitation prooess has been applied to treat acid mine water. The conventional ferrite preC1pitatlon requires air oxidation at high temperature, or long aging time or addition of magnetite powder ,as promoter. In this investigation, a modified ferrite, precipitation process is developed by which magnetic ferrite can be produced at an ambient temperature. Acid mine waters from Berkeley Pit (Montana, U. S. A.) and from Noranda Tailings (Quebec, Canada) were used. The co precipitation of heavy metals from these two acid mine waters is studied as a function of FeIM molar ratio, oxidation time and settling rate under applied magnetic field. The investigation indicates that the modified ferrite co precipitation can remove substantially all of the, dissolved metal ions from acid mine water. The ferrite product obtained after precipitation&apos; is characterized by XRD, SEM, BET and saturation magnetization. The results show that spinel ferrite, precipitation can be achieved at room temperature and the saturation magnetization of ferrite product from,acid mine water is comparable to that of pure ferrites.

Jan 1, 1995

By Suman Das, Justin J. Gambone, Rohan Bansal, Ranadip Acharya, Paul Cilino

"This paper focuses on generating a quantitative microstructure prediction model for Scanning Laser Epitaxy (SLE) process based on coupled flow-thermal modeling using Finite Volume method. SLE is a laser-based additive manufacturing process for the deposition of equiaxed, directionally solidified and single-crystal nickel superalloys through the melting of alloy powders onto superalloy substrates. In the current work, the detailed effects of natural and Marangoni convection on the flow field are studied and the results are analyzed in terms of the temperature gradient, vorticity parameter, melt pool dimensions and mushy region extent. The detailed property data of the processed superalloy and the laser scan path are incorporated in the model to predict the microstructure in realistic scenario. An optimization study is carried out to evaluate the critical parameter values at which the columnar-to-equiaxed and the oriented-tomisoriented transition take place. This work is sponsored by the Office of Naval Research through grant N00014-11-1-0670.IntroductionSLE is a laser-based additive manufacturing process for the creation of structures in equiaxed, directionally solidified and single-crystal nickel superalloys through the selective melting and resolidification of superalloy powders. In SLE, a tightly focused laser beam is guided by a highspeed galvanometer scanners allowing for tight control of the amount of energy being applied to the top of the powder bed, as well as the speed at which the melt pool moves across the substrate. Under the proper operating conditions and with sufficient substrate meltback, the solidification microstructure follows the morphology of the underlying substrate, allowing for directional and even SX growth.Several reports on the modeling aspects of laser cladding-based additive manufacturing approaches can be found in the literature. Approaches based on Finite Element Methods (FEM) and Finite Volume Methods (FVM) are employed for the thermal modeling of the system [1, 2]. Gaumann coupled the Columnar to Equiaxed Transition (CET) modeling with the Rosenthal solution in earlier work based on laser cladding [3]. Rappaz et. al. provided a detailed modeling of the microstructure/columnar orientation based on the solidification velocity and crystalline orientation [4]. This approach is based on the selection of the growth direction that closely follows the melt pool normal direction. Later on, substrate orientation is also taken into account [5, 6]."

Jan 1, 2013

By A. E. Clark

Rare earth compounds are widely known as possessing many extraordinary magnetic properties. In this paper, we focus on the huge magnetically induced displacements (magnetostrictions) which characterize the compounds of terbium with iron (Terfenol). Materials prepared commercially by both free-standing-zone (FSZ) and modified Bridgman (MB) techniques have now become available in large sizes and shapes. Prior to the development of the Terfenol alloys, it was possible to achieve giant magnetostrictions only at cryogenic temperatures. In the cubic Laves phase TbFe2 compound, saturation strains exceed 3000 x 10-6 at room temperature and above. Large magnetization &apos;jumps&apos; can occur, causing huge spontaneous magnetostrictions with small triggering magnetic fields.

Jan 1, 1992

By Cynthia K. Belt

Improved energy efficiency has grown in importance within industry as energy costs have escalated. The analysis of trends and changes to a process is critical in making the best business decision in energy management. Frequently, energy use per day (Kilowatt-Hour or British Thermal Units) is used to track energy efficiency. Sometimes, the somewhat more complex method of energy per processed weight (Kilowatt-Hour per Metric Ton or BTU per Pound) is used to make this evaluation. Yet both methods ignore the effects due to throughput and weather. In this paper, different thermal processes and systems will be evaluated using statistical methods to highlight alternative methods to evaluate energy efficiency. Examples and potential problems will be discussed for both a single process and a collection of processes within a plant or corporation.

Jan 1, 2008

By Richard D. Hagni

Reflected light microscopy is routinely applied to the study of ore minerals and textures in polished sections prepared from a wide variety of ore specimens. With the increasing interest in environmental problems, the important role of the reflected light microscope in the precise phase identifications and the determination of the textural relationships between those phases needs to be recognized. Among other environmental applications, the microscope has been applied to the recognition of lead smelter particles from remote collect sites in Missouri and those particles have been compared to dust particles from specific localities at the nearby lead sinter plant and lead blast furnace. Dust from a secondary copper refinery has been studied for its mineralogy. Soils in the vicinity of a Missouri lead smelter have been studied for their mineralogy in preparation to the clean up of those soils. Electric arc furnace (EAF) dusts, recently classified as hazardous waste by the EPA, have been examined for their mineralogy and textural intergrowth in order to better evaluate proposed metallurgical treatment procedures to render the dust non-hazardous. The initial products from experimental metallurgical treatment of EAF dusts also have been studied to aid in determining the effectiveness of those treatment procedures. Refractory gold sulfides that have been roasted in the presence of lime to retain environmental objectionable sulfur and arsenic while recovering the gold have been studied by RLM to determine their mineralogy, porosity, and permeability for cyanide leach solutions. These case histories illustrate the applicability of ore microscopy to the study of problems related to environmental concerns.

Jan 1, 1995

By James P. Bennett

The successful reuse/recycling of refractory materials after removal from industrial service is limited because of contamination, the low value of spent materials, the low cost of virgin raw materials, the lack of driving forces such as regulations or taxes, and low disposal costs. Most spent refractory is disposed in landfills. Concerns over future liability for waste materials, corporate images, and IS0 14000 have helped to encourage recycling at some companies. The recycling practices and application for spent refractory materials at facilities successfully recycling used refractory materials will be discussed, with emphasis on similarities.

Jan 1, 2002

By Akira Kaneda

Mitsubishi continuous process employs an electric furnace for settling matte from slag. Electrodes are immersed into the slag layer in the slag-cleaning furnace and the temperature of the melt is maintained at a predetermined level by Joule&apos;s heat. Electrodes are immersed to the depth where the current of each electrode is kept at a set value, and they are raised or lowered automatically to compensate for the deviation from it. Because electric resistance of the bath is varied with the matte level in the furnace and the composition and temperature of the slag, the immersion depth of the electrodes is affected by them. Therefore by monitoring the immersion depth and its change with time, abnormal situations in the furnace, such a~ rise of matte level or local abnormal state of melt, can be detected. In this paper, relations between state of the furnace and electrode behavior are discussed based on the plant data, and then a new and simple monitoring method of the condition of the furnace is proposed.

Jan 1, 2001

By Nils Eivind Kamfjord, Mari K. Næss, Halvard Tveit, Edin H. Myrhaug

"As a part of the FUME research programme being done by the Norwegian Ferroalloy Research Association (FFF), the SINTEF Group and NTNU, several measurements towards quantifying the gaseous and solid emissions from the draining of the silicon furnaces for metal have been carried out.Based on the measured size distribution of the formed fume particles and known particle growth theory, an estimate of the growth time for the given particles has been calculated. The formation time for the measured NO amount has also been calculated based on the fume measurements and a thermodynamic model of the furnace gases combusting with air. The two “formation” times are in the same order of magnitude and they are therefore used as parameters in a CFD model, modelling that the formed fume particles are heating up the surrounding air and thereby forming NO according to the Zeldovich mechanism. The measurements show an approximately equal constant NO formation per fume particle. The CFD model shows results in the same order of magnitude, supporting that the particle growth and NO formation happen under near stoichiometric conditions and are controlled by the formation of SiO2 fume.IntroductionNOx is the common notion for the two gases nitric oxide (NO) and nitrogen dioxide (NO2) formed during combustion of fuels. The main sources for human made NOx emissions is on-/offshore transportation industry, power generations based on fossil fuels, agriculture and other industries [1]."

Jan 1, 2012

By Raghavan Srinivasan, Y. V. R. K. Prasad, William G. Frazier, Steve C. Medeiros

"Aerospace gas turbine disks operate in an environment of relatively high stresses caused by centrifugal forces and elevated temperatures. These severe conditions necessitate the need for materials with good high temperature strength and low cycle fatigue resistance. One class of alloys used for this task is the nickel base superalloys, out of which, lN 718 is the most widely used in the aerospace industry [I]. The properties of IN 718 are attributed to the combined effects of the chemistry, heat treatment, and microstructure. The chemistry is tailored not only for solid solution strengthening but also for precipitation hardening developed during heat treatment, which combined with a fine grained microstructure lead to excellent mechanical properties such as low cycle fatigue resistance and elevated temperature strength. The properties of a gas turbine disk are sensitive to the microstructure, in particular the grain size, which is dependent on the processing history. The ability to precisely control the microstructural development during forging is dependent on controlling the process so that the workpiece is deformed within a ""safe"" region where no microstructural damage or flow instabilities occur. The microstructural mechanisms during deformation may themselves vary within the ""safe"" region and it is desirable to determine them within the range of parameters that are commonly used in industrial processing. The objective of this work is to establish a relationship between the grain size and the process control parameters i.e., temperature and strain rate, in the hot working of IN 178.BackgroundIN 718 belongs to a class of nickel-iron base superalloys with a face-centered cubic (FCC) austenitic matrix strengthened by precipitation of ordered intermetallic or carbide precipitates and is a nickel-rich alloy strengthened by ordered body centered tetragonal (BCT) precipitates, Y"". The alloying of nickel and iron results in the formation of the austenitic matrix, y, while the addition of chromium and molybdenum cause solid solution strengthening. Also, alloying with niobium causes precipitation of the metastable hardening constituent Y"" (Ni3(Nb,Ti)). Extended aging treatments in the temperature range 650 °C - 980 °C allow the more stable orthorhombic 8 phase (Ni3Nb) to form. Trace amounts of boron are also added to serve as grain boundary strengtheners for high temperature creep resistance. Hot deformation of IN 718 is performed between the Y"" and 8 solvus temperatures to facilitate recrystallization and to control grain growth. While deformation below the Y"" solvus (""""962°C) produces no change in grain size, deformation above the Y"" solvus but below the 8 solvus will lead to a dynamically recrystallized microstructure. The presence of the 8 precipitates will pin the grain boundaries after recrystallization and restrict grain growth so that a fine grain microstructure is obtained. Deformation above the 8 solvus ("""" 1038°C) will lead to a microstructure which has undergone grain growth during deformation."

Jan 1, 2000

By H. K. Lin

Pyrite oxidation in chloride solutions was investigated with cyclic voltammetry, ac impedance and potential step techniques. The pyrite oxidation in quiescent electrolytes is irreversible and controlled by diffusion. Depression of the semi-circle in the complex plane plot has been explained mathematically based on the concept of the equivalent circuit. When the semi-circle is depressed, the mathematical formula indicates that the reaction resistance should be obtained from the intersection of the semi-circle with Z-axis instead of the semi- circle diameter. The peak charging current densities at 1.10 and 0.90 V vs. SHE obtained from the equivalent circuit coupled with the ac impedance measurements match the peak current densities obtained with the potential step measurements.

Jan 1, 1997

By Frank Mucciardi, Hujun Zhao, Pietro Navarra

"A heat pipe is a device having a very high effective thermal conductivity in which two-phase flow and heat transfer takes place. Recent research at McGill University has led to a new type of heat pipe that contains a flow modifier. This improvement has enabled the device to operate at the high heat fluxes encountered in the metallurgical industry.This paper summarizes the progress made to describe the fluid flow in the evaporator section of a McGill heat pipe with the goal of understanding how the flow modifier configuration is linked to the film boiling and dry-out limitations. A separated flow model, an instability analysis, a lift-off model and an energy balance model are used to calculate the theoretical CHF with varying flow modifier configurations and operation conditions. A summary of the current work to relate the flow modifier to the dry-out limitation is also given.Determining how the flow modifier affects both the film boiling and dry-out limitation will give insight into improving the flow modifier design so as to extend the operational range of McGill heat pipes in terms of maximum heat flux and heat load capabilities.IntroductionThe McGill heat pipe is a specialized two-phase heat exchanger developed for several metallurgical applications where temperatures and heat fluxes are typically close to or beyond the maximum safe range of conventional cooling technology.Over the last few years, several breakthroughs have brought this device beyond the proof-of concept stage and a series of industrial trials have been performed with success. These trials include two oxygen injection applications for the ferrous and non-ferrous industry [l], and two light metals permanent-mould casting applications [2,3]. Current projects include a blast furnace copper taphole cooling application [4], a copper smelting application and a thermal analysis probe application."

Jan 1, 2004