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By Buket Tunçer, Mehmet Buğdaycı, Onuralp Yücel

ZrB2 and TiB2 are one of the most significant metal borides. They are being used in various industrial areas from space technology to nuclear industry owing to their physical properties such as high melting point, high thermal/electrical conductivity and low density. Present study was conducted in two main stages: Self-propagating high-temperature synthesis (SHS) reactions and leaching. ZrO2, TiO2, B2O3 were used as starting material and Mg used as a reductant to produce ZrB2-TiB2 powders via SHS. Therefore, it was aimed to determine production parameters, leaching conditions and comprehensive examination of final product features. The samples were characterized by using chemical analysis (AAS), XRD, XRF and SEM/EDS techniques

Jan 1, 2015

By Jaeheon Lee

Gold-copper alloys are shown to form during the cementation of gold on copper in a solution containing 0.25M [S2O32-] at 25oC. The alloy composition is strongly dependent on the initial Cu:Au ratio in solution and ranges from Au3Cu to AuCu3. XPS results for Au, Cu, S, and O are reported as a function of depth through an entire deposited film with an initial solution containing 20 ppm [Au] and 30 ppm [Cu]. The deposit contained about 20 atomic % gold and was predominantly Cu3Au. Underpotential deposition (UPD) theory is discussed as a mechanism for explaining the formation of these alloys. Several other systems that produce alloys during contact reduction/cementation are also discussed.

Jan 1, 2003

By V. I. Lakshmanan

"Historically flowsheets are developed for efficient separation of metals for economic recovery. With increasing emphasis on reduction, reuse and recycle (3Rs) efficient methods are sought to recover values from a variety of feeds where cost of collection, transportation, local consumer behaviour and regulatory guidelines dictate the development of economically viable flowsheets. Innovative understanding of potential market applications can provide means to develop value added end products. The paper with examples will discuss the use of innovative-separation technologies to obtain value added end use materials from secondary sources.IntroductionFlowsheets are developed for the efficient separation of materials of value for economic recovery. However with increasing societal pressures and regulatory initiatives for stricter environmental guidelines, there is strong need to provide focus to recover materials efficiently and economically in an environmentally accepted manner. North American industries are increasingly caught between demands for high technology value added products and responsibility for environment. An aspect that is receiving increasing attention is Design for Environment'. This incorporates a system wide approach for product design and incorporates environmentally preferable features such as recyclability, disassembly, maintainability, reusability and use of safe materials as part of a product's design objectives.The present paper with case histories will address innovative flowsheet development to convert wastes into recyclables value added products or for minimising generation of waste materials. Case HistoriesProcess for Separating Fibres from Composite Materials 1In the automotive industry, sheet molded compound (SMC) is used to produce panels, bumpers and the like. During the manufacture and at the end of life, considerable waste materials are generated which are potentially recyclable. Fibre reinforced plastics where fibre substrate impregnated with thermosetting resin, find applications in several manufacturing processes and are potentially recyclable at the end of life."

Jan 1, 1996

By Suzzann Nordwick

Over the past decade, significant advances have been made in the development of sulfate-reducing bacteria (SRB) technology to treat acid mine drainage (AMD). Bench-scale testing, field demonstrations, and engineered applications of SRBs for the treatment of AMD will be presented. Designs include an in situ bioreactor installed in the subsurface workings of the Lilly Orphan Boy Mine in 1994, the SRB bioreactors installed at the Calliope Mine from 1998 to 2001, the integrated biological reactors built at the Surething Mine in 2001, and the ongoing development of a replaceable cartridge system. SRB technology benefits include the reduction of dissolved metal ions to insoluble metal sulfides and the neutralization of the AMD resulting from the production of bicarbonate from the oxidation of organic nutrients. This paper will address engineering design criteria including the selection of organic media and system permeability and complete mitigation of AMD. Research was funded under Interagency Agreement No. DW899388-70-01-1 between the US EPA and the US DOE and was conducted by MSE Technology Applications, Inc., through the National Environmental Technology Laboratory (DOE Contract No. DE-AC22-96EW96405) at the Western Environmental Technology Office located in Butte, Montana.

Jan 1, 2003

By Luben Xie, Lin Hu, Qiang Wang, Min Gan, Tao Jiang, Wenqi Li, Xiaohui Fan, Zhiyuan Yu

"Crystal precipitation behavior of calcium ferrite (CF) during iron ore sintering process along with the effect of cooling rate, SiO2 and Al2O3 on crystalline condensation were studied. The results show that CF, has strong ability of precipitation. The precipitation is barely affected by extenal factors. It begins to precipitate when the liquid phase cools down to about 1200oC. CF could crystallize rapidly at the cooling speed of 150 °C /min. Furthermore, decreasing of the cooling rate favors the development of crystal. Binder phase transformed from CF system to silicate system when SiO2 content was increased to 5~6%, with a constant basicity (R) 2.0. Increasing Al2O3 content could promote the precipitation of CF and the development of crystal.IntroductionCrystalline condensation is the last stage of sinter mineralization. It includes the processes that crystalline substance and amorphous substance precipitate from high temperature solution phase and the consolidation of material when melt cools down. During the crystallization process, minerals precipitate following the order from high to low melting point coupled with the decreases of free energy. Most of binder phase minerals and part of iron oxides crystallize in this process, which have an important influence on mineral composition and microstructure of sinter. They finally determine the sinter strength and metallurgical properties."

Jan 1, 2011

By Darryl Lovato, Ramiro Pereyra, Daniel S. Schwartz

"During an annual inventory of nuclear material, a plated steel container which contained plutonium oxide failed. The container had been packaged for temporary storage but had been overlooked and remained in storage for more than 23 years. Although it was determined that the failure occurred through the slip-top rim, a metallurgical evaluation was requested to help to determine the integrity of the container.Optical metallography and scanning electron microscopy were used to analyze the character and degree of corrosion in the container. The depth of corrosion, measured at approximately 10 µm, did not pose a threat to the integrity of the container. However, the corrosion morphology and chemistry did suggest that a galvanic cell had developed between the tin and steel from the condensation of water. The morphology also suggests that the attack of the steel took place over a series of cycles due to changes of the environment.IntroductionMetallographic analysis was requested as part of the investigation into the mechanism of the failure of a slip-top container (#38621) containing plutonium oxide (PuO2) powder. The container had leaked during a special nuclear material (SNM) annual inventory causing contamination and closure of the vault. A photograph of the container and interior container is shown on the right in Figure 1. An initial investigation established that the source of contamination was the consequence of the failure of multiple layers of containment. Initially by the deterioration of the interior plastic bottle and polyvinyl chloride (PVC) bagout bag, and finally through the lid and steel container interface at a location where tape had not adhered properly [1]. Although the source of the breach was established, it was determined that metallographic analysis was important to establish the extent of deterioration of the steel container."

Jan 1, 2008

By J. R. Parga

A shortage of landfill space and growing environmental concerns in Mexico are renewing interest in the recyclability of scrap from automobiles. This work describes a pyroumetallurgical process for the recovery of metallic lead from waste lead paste. Argentopyrite concentrate is commingled with lead paste residue and smelted in a fuming process thereby transferring the precious metals into lead bullion. The process consists of smelting lead paste and argentopyrite, sodium carbonate, and metallic iron at smelting temperatures of about 1100 T. The reaction products are slag and molten lead bullion enriched with precious metals. A major feature of this process is the removal of precious metals from the bullion by means of zinc, whereby a silver-zinc intermetallic compound is formed and floats out of the lead. The recoveries of precious metals are about 98%.

Jan 1, 1996

By G. A. Brooks

The problem of treating concentrates with increasingly higher levels of arsenic and antimony is compounded by the trend to stricter environmental guidelines regarding the disposal of smelter wastes. Much of the arsenic and antimony from non-ferrous processes is recovered as oxide fume. The options for handling these fumes include recycling them to the smelter, stabilising and disposing of them, and recovering values from them. Whilst arsenic oxide has little value, there is a market for antimony oxide and this provides an incentive for devising techniques for separating antimony oxide from arsenic oxide before disposal of the arsenic oxide. Arsenic can be separated from antimony oxide by selectively volatilising the more volatile arsenic trioxide from a mixed oxide sample or by selectively condensing the less volatile antimony tetroxide at high temperatures, leaving arsenic trioxide to condense out at lower temperatures. The results of selective volatilisation experiments at 379 to 587 °C indicate that it is difficult to achieve an arsenic content below 5.0 wt.% using air or nitrogen as carrier gas due to the formation of solid solutions between the two oxides. Injection of oxygen into a mixed vapor stream improved separation by selective condensation and antimony tetroxide containing as low as 0.23 wt.% was obtained in laboratory experiments.

Jan 1, 1994

By W. G. Davenport

A survey of world copper refining tankhouse .practices has been carried out. This paper compiles the results and examines changes in operating practices .since the similar 1987, 1991 and 1995 surveys. Continuing trends are the installation of ISA Process and Kidd Process stainless steel cathode technology, polymer concrete cells, anode preparation machines and automatic cranes. Instrumentation and automatic control are increasing, particularly for addition agent optimization; solvent extraction .and ion exchange techniques are being increasingly applied for electrolyte purification. The overall consequences of these changes have been 'improved cathode purities and enhanced tankhouse productivities.

Jan 1, 1999

By Robin D. Rogers

Room temperature ionic liquids (RTIL) can replace certain traditional organic solvents in liquid/liquid extraction of metal ions from aqueous systems. The very low vapor pressure and non-flammable nature of RTIL warrant consideration of these neoteric solvents for new processing technologies which will reduce pollution, Increase safety, and lower costs. Metal ion separations in RTIL, however, will typically require the use of an extractant and research is needed to identify suitable selective extractants which have appreciable solubility in the RTIL and low solubility In the aqueous phase. Choice of extractant should also take into account the toxicity, expense, and disposal of the ligand.

Jan 1, 1999

By V. Vergara

Four copper composites were obtained by mechanical alloying, using as dispersed phases of four carbide powders; they were: boron carbide, chromium carbide, silicon carbide and zirconium carbide. The purpose of this work was to study some characteristics of these compounds and their feasibility for use as materials for electrical equipment. Raw materials used were copper powder finer than 150 mesh, and 2-4 vol % of powder carbides finer than 325 mesh. The alloying process was carried out using both a Spex 800-D mill with tungsten jars and balls and a hardened stainless steel jar and balls, the purpose of which was to measure the degree of contamination induced by the milling media. The changes in particle size, morphology and microstructure of copper alloys were studied with SEM and TEM for each alloyed powder. The degree of saturation of copper by the carbides was measured by X-ray diffraction. Sound samples were obtained by hot isostatic pressing at 1073°K. The best characteristics were obtained for the compound copper-chromium carbide, based on their hardness, tensile strength and electrical conductivity values. The other alloys failed due to their excessive brittleness after hot pressing.

Jan 1, 1999

By Barry J. Welch

The production of primary aluminium can potentially lead to metal that, with minimum treatment, meets a high purity standard. Smelters that can achieve a significant proportion of their production in this manner have a competitive edge which is of growing importance as the use grows for such items as compact discs and the like. Superimposed on the desire to produce high quality metal are stringent environmental requirements that the industry must adhere to. The environmental 'legislation focuses on fluoride emissions and the approach adopted is towards a zero waste management philosophy. The fluoride recycling process does, however, result in volatile impurities being captured and recycled to the cell. Aluminium has an extremely high reduction potential and this results in a significant proportion of the recycled impurities being reduced at the electrolyte metal interface and thus contaminating the metal. This paper reviews sources of impurities and the impact of the operating procedures adopted on metal treatment.

Jan 1, 1996

By Yuzhe Zhang, Xiaodi Huang, Xinli Wang, Bowen Li, Matthew Andriese, Jiann-Yang Hwang, Zhiwei Peng, Likun Li

With the development of the world, the waste tires have been a serious environmental problem. There are about 2 billion waste tires produced all over the world every year and about 500 million waste tires are produced in the United States. Most of the waste tires are land filled, which waste a lot of space. It takes hundreds of years to resolve the macromolecules of waste tire into the standard which does not pollute the environment. Microwave irradiation is a thermal processing way for waste tires decomposition. In this study, the relative dielectric loss factor of the tire at various temperatures was determined to understand the behavior of tires under microwave heating.

Jan 1, 2016

By C. Lupi

The electrorefining of primary copper is a well known technology: in this work copper scrap was directly processed in the same way. he copper and copper alloy scrap was previously pressed by means of a 20 tons apparatus in order to avoid pyrometallurgical operations. The samples obtained in this manner showed a good compactness so that they were used as anodes in the electrorefining tests. The tests were carried out on anodes made by copper scrap, copper alloy scrap and a mixture of the two. The electrorefining tests were performed at both 303 and 333 K, in a perspex cell having a volume of 500 ml using a current density of 250 A/m2. The cathode used was always a sheet of pure copper and the electrolyte composition was 40-50 g/l Cu as CuS04 and 150-200 g/l H2SO4. Current efficiency in the range of 92-97% and specific energy consumption ranging from 0.14- 0.20 kWg of copper were reached in all the tests. The refined copper deposits were analyzed by AAS to verify their purity and observed by SEM to highlight their morphology.

Jan 1, 1998

By K. Sanjay

Factorial optimisation technique has been used to develop regression equations at different time intervals for extraction of manganese from precipitated manganese oxide/hydroxide in sulphuric acid using charcoal as the reductant. The three parameters chosen for a 23 full factorial design were : acid concentration, amount of carbon and temperature. The regression equations were used to predict >> 90% extractions as well as kinetic data.

Jan 1, 1996

By K. Iwami, K. Abe

"Onahama Smelter and Refinery has been operated-since 1965 arid currently produces 243,000 metric tons per year of cathode copper. The Onahama tankhouse consists of conventional-type No.1 and 2 tankhouses with the capacity of 123,000 metric tons per year and No.3 tankhouse with 120,000 metric tons per year, adopting jumbo tank system, using hazelett anode respectively.In October, 1996, for the purpose of improving the - anode verticality, new anode copper body press machine has been installed in No.1, 2 tankhouses; by increasing Walker type anode copper weight by 35kg to 365kg. Consequently, it is possible to raise current density from 191 to 222 A/m2 and the No.1 and 2 tankhouses capacity was increased by 15,000 metric tons per year to 138,000 metric tons per year.At present, the refining capacity is 258,000 metric tons per year in total including No.3 tankhouse.This figure is the largest one in Japan.IntroductionSince the Onaham tankhouse was put into operation in 1965, the cathode copper production has increase with much labor cost saving.The following two cases to increase Walker type anode copper weight by 35kg to 365kg were studied.a) To increase the cathode copper production by raising current density.b) To save the labor cost by prolonging the anode cycle in order to decrease the exchanging time of electrodes.So the electrolytic tests were carried out to confirm· the effect of current efficiency, cathode copper quality and working conditions for space adjustment.As a result, we concluded that it was indispensable to introduce the anode body press machine to keep usual current efficiency and cathode copper quality with same workers, and to be possible to increase cathode copper production.In addition, the high-speed press machine was needed to maintain same working time and which specifications were decided through various investigations. In October 1996, the new anode body press machine made by Kawazoe Machine Works, Ltd. has been installed in No.1 tankhouse."

Jan 1, 2000

By M. Okido, O. Takai, Z. Zhao, M. Ishikawa, R. Ichino, K. Kuroda

"Electrolytic method was applied to calcium phosphate coating on titanium plates as an excellent technique for high density and intensive contact of coated films on biomaterials. The effect of H2O 2 as oxidation reagent on coating characteristics was examined to obtain biomineral films. Solution was containing 7.0 X 10·3 mol/dm3 ofCaC12 and 3.0 X 10·2 of Ca(H2PO4)z, kept at 55 ""C. All deposits were hydroxyapatite (HAp) in this study, independent of H2O 2 concentration, applied cathodic potential and solution pH. In the case of H2O 2 addition, an increase in cathode current started at the low potential, namely, ca. -0.2 V (vs. SCE). In contrast, the current increased at more than ca. -1.4 V in the solution without H2O 2 addition. H2O 2 appeared to be an effective reagent for increasing nucleation density and improving adhesion of deposits on titanium plates.IntroductionIn recent years, many researches have been undertaken to develop the techniques of calcium phosphate coating on titanium or bioglass for medical implantation. High density and intensive adhesion of coating are necessary for adding bioaffinity to these materials and for inducing bone morphogenesis on them when implanted in human body.1) Electrolytic deposition has been a newly developed method as high-speed deposition process. By this method, the supersaturation of calcium phosphate can be increased just in the vicinity of metal substrates and the heterogeneous nucleation is promoted on them. In this process, H2O is reduced according to eq. (1) on the cathodically polarized electrode"

Jan 1, 2000

By Pengcheng Li, Wei-Tong Du, Yu Wang, Gang Wen

Carbon dioxide could be utilized as a weak oxidant and a kind of coolant to oxidize elements, meanwhile, helping control the temperature during the converter vanadium extraction process. However, the optimum content of CO2 and the cooling effect of CO2 at low content have not been reported. In this study, experimental research based on the influence of different CO2 contents from 0% to 25% injected to the vanadium-containing hot metal was carried out, as well as contrast experiments of O2-N2 mixed blowing. The results indicated that the optimum content of CO2 was 15%. Under the optimum condition, the oxidation of [C] was the lowest and the oxidation rate of [V] was 96.9%, while the temperature was also lower than the O2-N2 mixed blowing. This paper provide a potential property for utilizing CO2 during the converter vanadium extraction process.

Jan 1, 2016

By Nelson Collao I.

Loss of the organic phase from solvent extraction circuits is a major cost factor for SXEW operations. Recognized sources of loss include evaporation, entrainment, and biological degradation. The mechanisms for both entrainment and evaporative losses are well recognized. Biological degradation of the organic has not been as extensively evaluated as the other mechanisms but is a major source of loss. This paper discusses the impact of biological degradation on an operating plant, potential mechanisms for degradation, conditions under which biodegradation of plant organic can occur and plant conditions that may assist in promoting biodegradation.

Jan 1, 2003

By A. G. Jackson, Mark D. Benedict, Steven R. LeClair, Yang Cao, David M. Conrad

"Electronic Prototyping (EP) represents a new and powerful medium that many in science and technology view as the research paradigm of the future. Actually, EP has many handles, sometimes referred to as simulation-based design involving more long term objectives such as virtual reality, but regardless of the 'spin', the direction of EP is an enhanced visual paradigm to enable a new set of tools for engineers and scientists alike. Tools to not only automate, visualize and compute otherwise intractable problems but to enable augmentations of our ability to perceive that which is interesting and new -""a virtual version of a process"" [1] prodding us on the pathways of materials and process discovery.IntroductionActually there are many reasons to apply sensors to materials, such as smart or adaptive materials/structures, and new materials synthesis/processing [1], only some of which are motivated by improved product quality and/or productivity. Although U.S. Air Force applications of sensors to materials processing represent but one of many perspectives, hopefully it is a perspective which will engender new ideas and insights in addressing future challenges in materials research. To provide context and establish need for future sensor applications in materials processing, we will utilize on one of several Air Force vistas or '21st-Century' objectives."

Jan 1, 1997