Search Documents

By Banqiu Wu, Ramana G. Reddy, Robin D. Rogers

Experimental studies on aluminum recycling via electrolysis in ionic liquids were carried out at the temperature of 105°C. Impure aluminum was dissolved at the anode and pure aluminum was deposited on a copper cathode. The products were characterized using an optical microscope, micro-image analyzer, X-ray diffraction, emission spectrometer, and atomic absorption analyzer. The electrorefining process with a current density of 310 - 730 AJm2, and current efficiency of about 99% was obtained. Impurities such as Si, Cu, Zn, Fe, Mg, Cr, Ni, Mn and Pb were removed as anode residue. Impure aluminum was purified from 79.8wt% to 99.9wt%. At a cell voltage of 1 volt, the energy consumption of about 3 kWh/kg-Al was obtained. The process has advantages of low energy consumption and low pollutant emissions, compared with the current industrial refining process.

Jan 1, 2000

By Giovanni Principi

The activity of the ?Hydrogen Group? of Padova University, addressed to the study of materials for solid state hydrogen storage, is illustrated. Various Mg-based materials have been considered and are being studied: a) MgH2 and 0.5% mol Nb2O5 mixture ball milled under argon atmosphere; b) Mg-Ni-Fe intermetallic compounds prepared by short time ball milling of ribbons obtained by melt spinning and by long time ball milling of a mixture of MgH2, Ni and Fe powders; c) MgH2 ball milled in argon with Mm-Ni-Al (Mm = La-rich mishmetal) and Zr-Cr-Fe catalyst alloys. All the samples have been structurally characterized by X-ray diffraction (Rietveld refinement) before and after hydrogen absorption/desorption cycling and tested with a Sievert apparatus as regarding their thermodynamic and kinetic properties.

Jan 1, 2006

"Injection technology has been an important subject from the early days of ladle metallurgy until the present. During the last decade, there have not been many publications in the area of injection technology. It is the author's opinion that with the challenge to find new solutions especially to environmental and energy related problems as well as better understanding of phenomenas from computer modelling, a new era of inventive injection technology developments is at hand. This is illustrated in the article with examples from six different areas where MEFOS is or have recently carried out R&D work related to issues from the injection technology field. IntroductionThe boom in injection technologies came with the introduction of ladle metallurgy treatment during the '70s and '80s. Since then, the theories and principles have been thoroughly laid down by a number of scientists and also published at several early SCANINJECT conferences.Not many new technologies/applications have been presented during the last ten years. This might lead one to believe that everything is known and done. Those, like MEFOS, who are challenged to find technological solutions to a number of environmental problems and energy saving issues in the pyrometallurgical field are, however, continuously faced with the task of developing new injection technologies.Especially, the call for sustainable technologies to solve environmental problems is a challenge for metallurgists all over the world and it will surely induce a revival of injection technologies. So, in order to encourage all injection experts, let us share some new experiences and let us encourage each other's creativity to solve some of the demands of the future society.The following show some examples of technologies under development, or recently tested."

Jan 1, 1996

By Justin Karl, Ali Gordon, James DeMarco, Yongho Sohn

"Aluminum metal-matrix composites are lightweight materials that have the potential to supplant steel in many applications. The current work helps to identify the parameters that confer maximal strength and ductility. Torsion tests were performed on the as-cast aluminum metal-matrix composite A359-SiCp-30% at a variety of temperatures and twist rates. Dependence of material properties on temperature and strain rate were identified from equivalent stress-strain curves constructed from the reduced data. Examination of the microstructure was performed on the as-cast material and on fracture surfaces. A temperature-and strain rate-dependent constitutive model was applied to simulation of the mechanical response of the torsion specimen. Trends in material properties corroborate and extend trends identified previously under tensile loading with regard to temperature and strain rate dependence. Shear properties of simulated specimens agree with properties obtained through experimentation.IntroductionAluminum metal-matrix composites (A1-MMCs) have become increasingly popu1ar in recent years. While unreinforced aluminum alloys have low densities and high ductilities, they are not suitable for many applications due to their lack of strength and stiffness. To provide added strength and stiffness while maintaining favorable densities, it has become common to reinforce aluminum alloys with silicon carbide in various forms, although usually the inclusions are in the form of whiskers or particles. The result is a composite material with superior specific strength and stiffness. While whisker-reinforced composites are expensive due to the necessity of processing by nonstandard techniques and have low transverse properties when rolled, particle reinforced Al-MMCs have transverse material property values almost as high as the longitudinal properties and are not as expensive to process as whisker-reinforced Al-MMCs [1]."

Jan 1, 2012

By Douglas M. Matson, Rongbiao Gu, Christopher San Marchi, Anil Saigal

"Hydrogen embrittles most structural metals, although the form and magnitude of embrittlement depends on the source of the hydrogen as well as the stress in the metal. Hydrogen fuel cell systems typically store gaseous hydrogen fuel at high-pressure, which provides both a source of hydrogen and high stresses in the containment materials. Understanding and measuring the effects of hydrogen on the mechanical properties of common structural metals, especially fatigue properties, is important for safe, long-term operation of such systems. This work explores the use of thermography to efficiently and quantitatively evaluate hydrogen-assisted fatigue of type 304 austenitic stainless steel. In particular, thermographic analysis was used with rotating-beam fatigue testing and shown to provide repeatable results which are in general independent of test cycle frequency while reducing test times by several orders of magnitude. The effects of hydrogen were studied by thermally precharging fatigue test specimens in gaseous hydrogen prior to thermography-assisted fatigue testing and then compared to testing of non-charged specimens. Hydrogen-precharging increased the strength of this type 304 austenitic stainless steel and increased the fatigue life by a factor of about 50-100.IntroductionThe world is facing a severe energy and environmental challenge: how to provide competitive and clean energy for its citizens in light of an escalating global energy demand and concerns over energy supply security, climate change and local air pollution. As a carbon-free energy carrier, hydrogen provides a promising vector for storing and distributing renewable energy. Hydrogen is an important industrial gas that is used extensively in many industries. However, with growing demand for clean energy, hydrogen fuel cell systems are being developed for use in consumer products, such as fuel cell vehicles, which changes the landscape for safe design of high-pressure gaseous hydrogen systems."

Jan 1, 2012

By Samir N. Shoukry, Mourad Y. Riad, Gergis W. William

"Setting of concrete material is defined as the transitional period between states of true fluidity and true rigidity. Initial and final setting times are measured in the laboratory on the mortar sieved from the mix in a controlled environment where temperature and moisture values are constant. On the other hand, field applications are held in outdoor environments where environmental variations have direct impact on setting time values. In this study, initial setting time of class K concrete, usually used for bridge decks and concrete pavements, are investigated highlighting discrepancies between laboratory and field measurements. 72 mixes have been cast in variable environments and collected data from concrete mixes and the ambient conditions are reported. In light of the collected data, the effects of variable setting times on early age cracking of concrete material are studied and means to minimize such cracks are presented.BackgroundSetting of concrete material is defined as the transitional period between states of true fluidity and true rigidity [1]. Continuous hydration of the cement within the matrix transfers the mix from a state of setting to hardening. Initial and final Setting times are measured in a laboratory setting following ASTM C 403 specifications. Initial setting approximates the time at which the cement paste can no longer be plastic under compaction (or can be handled in a proper fashion), while the final setting approximates the time at which hardening occurs. The standard test described in ASTM C 403 is conducted on the mortar sieved from the mix (paste passing from 4.75 mm sieve opening). Initial and final settings are described as the elapsed time after the initial contact of water and cement till the mortar reaches a penetration resistances of 3.5 MPa (500 psi), and 27.6 MPa (4000 psi) respectively."

Jan 1, 2012

By Jorge Alberto Soares Tenório, Denise Crocce Romano Espinosa, Luciana Harue Yamane

"The present work investigated the influence of Fe+2 initial concentrations in the bioleaching of copper from printed circuit board using Acidithiobacillus ferrooxidans-LR. Printed circuit boards were collected from obsolete computers and mechanically processed through size reduction followed by magnetic separation. The bacteria Acidithiobacillus ferrooxidans-LR were grown and adapted in presence of printed circuit boards. A shake flask study was carried out on the printed circuit boards samples (non-magnetic fraction) using a rotary shaker under the following fixed conditions (185 rpm, 30°C). The bioleaching efficiency was evaluated by comparison between the concentration in the initial sample and in the leached liquor, pH of the medium and concentration of ferrous iron produced. Inductively coupled plasma optical emission spectrometry (1CP-OES) was used to determine the metals concentration. The results showed that Acidithiobacillus ferrooxidans-LR leached 63% copper from printed circuit boards using supplemented medium with Fe+2.IntroductionThe waste of electric and electronic equipment is generated by discarding of equipment such as obsolete computers and cell phones which is stimulated by the technology innovations and it has been growing each year. Because of the amount that has been accumulated it has become a prominent environmental problem but also can be a source of valuable materials, such precious and base metals [1,2] The printed circuit boards are found in almost all electric and electronic equipment being composed of polymers, ceramics and metals and can be an alternative source to recover base and precious metals. The precious metals are used in the printed circuit boards to protect against oxidation and base metals because of its conducting properties [3]. The heterogeneous composition of printed circuit board is a limiting factor in the recycling processes and the metals concentrations also range."

Jan 1, 2011

By Xiangru Chen, Qijie Zhai, Wei Zhang, Haicheng Li, Chao Yang

In this paper, ductile iron material with different content of niobium was prepared by a scientific melting method. Image Analysis Software was used to studied the effect of niobium microalloying on both pearlite content and pearlite lamellar spacing in ductile iron quantitatively. The results showed that the addition of a small amount of niobium could increase the pearlite content and decrease pearlite lamellar spacing of ductile iron effectively.

Jan 1, 2015

By Kurt Westerlund

Three. years operating experience of the FLUXFLOW waste heat boiler (WHB) 20.000 nm /h at Boliden Ronnskar Sweden on a TBRC smelting palena (PbS). Operating experience from the Kivset flash WHB 11.900 nm /h at Samim, Porto Vesme, Sardinia, Italy. Conceptual features of the 93.600 nm3 /h FLUXFLOW (WHB) on the Isasmelt smelting in melt furnace for 180.000 t Cu/a at Mount Isa, Australia.

Jan 1, 1992

By Jitka Jandová

A laboratory process based on simple and environmental friendly operation, aimed at recycling of spent Li/MnO2 batteries, is described in this study. This process involves roasting Li/MnO2 batteries in a vacuum furnace at 650°C, followed by selective leaching Li2CO3 from calcined electrode material in distilled water at ambient temperature and controlled crystallization of pure Li2CO3.

Jan 1, 2006

By S. de Vries, B. Wasmund, J. Metric, N. Voerrnann, S. Kasinger

Gulf Chemical & Metallurgical Corporation (GCMC) operates a circular DC electric smelting furnace to treat nickel and cobalt bearing residues at its plant in Freeport, Texas. The furnace, originally built by others, has experienced problems including runouts through the hearth and the lower sidewall. Hatch has designed several improvements to the furnace to alleviate these problems. The single anode at the centre of the hearth was replaced with a patented system of twelve air-cooled copper anodes evenly spaced around the furnace lower sidewall. The DC power supply comprises two transformers and two rectifiers operating in parallel. The water-cooling system on the bottom and lower sidewall shell plates was replaced with an air-cooling system using copper cooling fins. The existing row of water-cooled copper coolers in the metal bath zone was re-designed for greater heat removal capacity and better element joint sealing, and a new row of water-cooled copper coolers was added to cool both the alumina bath and freeboard zones. The existing water-cooled metal and alumina tapblocks were also re-designed for more robust cooling. A binding system was added to provide refractory compression that reduces the risk of liquid leaks. Finally, the furnace tilting frame was relocated to the top of the furnace where it is less likely to be damaged.

Jan 1, 2000

By M. Oliazadeh

The present study was performed to develop a process for solvent extraction of molybdenum and cobalt from an acidic solution generated by an electrodeposition process of nanocrystalline cobalt alloys. Solvent extraction is a common practice in hydrometallurgical and refining processes to produce metals; however its application for separation of molybdenum and cobalt from this specific solution is new, because molybdenum and cobalt are not commonly associated together in nature. Five commercial organic extractants were examined for extraction of cobalt and molybdenum from synthetic acidic solutions with pH ranging from 1 to 5. Preliminary results showed that at pH 2, any of the Cyanex 923, Alamine 336, Aliquat 336 and Hostarex A327 could be used to extract 99% of molybdenum from solutions, while from pH 3 to 5, Aliquat 336 was able to extract about 100% of molybdenum. Cobalt extraction, on the other hand, varied from 15% to 23% at pH 3 and 30% to 53% at pH 2 using different extractants. Based on results obtained, Aliquat 336 was applied on mixed solutions of cobalt and molybdenum at various pHs. The results showed that molybdenum could be extracted as much as 99% from a mixture of molybdenum and cobalt at acidic pHs, while less than 1% of cobalt was separated at pH 2 to 4 simultaneously.

Jan 1, 2003

By H. Walqui

Southern Peru Copper Corporation (SPCC) are currently modernizing the Ilo copper smelter. A single ISASMELT furnace will start smelting 1,200,000 tonnes per year of concentrate during the second half of 2006. The existing Peirce Smith converters are being upgraded for converting the matte to blister copper and a new acid plant and oxygen plant are being installed. Two new anode furnaces and a twin anode casting wheel have been installed in 2005 and commissioned in January 2006. The modernization project will ensure the smelter satisfies new environmental regulations due to come into force in January 2007. This paper summarises the background to the modernization project, describes the main design features of the new copper smelter and summarises progress on the smelter construction as of early 2006. This paper describes the genesis of the Ilo Smelter Modernization Project and describes in details the scope and current status of the project.

Jan 1, 2006

By E. A. Román

An ion exchange pilot plant, provided by Mesco Inc., was tested for antimony control in the electrolyte at three Chilean tankhouses for copper electrorefining: Chuquicamata, Potrerillos and Enami -Ventanas. The pilot plant, with a nominal extraction capacity of 1.2 kg Sb/day, worked connected to both experimental and commercial circuits, performing a total of 310 loading and elution cycles. An innovation in this process is the use of a chelating organic elution reagent, which presents some advantages over the traditional 6N HCI. This new eluent is amenable to continuous regeneration and recycling with high recovery efficiency. Antimony removal starting at initial, concentrations of 0.5 to 0.6 g/l of Sb down to steady concentrations of 0.1 to 0.0.6 g/l Sb, resulted in the production of High Grade copper cathodes with Sb contents below 0.1 ppm. Anodic slimes showed Sb contents below 1%.

Jan 1, 1999

By J. Michael Canty

Over 25 years of US research in Mineral Recovery from Geothermal Solutions have lead to few commercial applications. With the World Bank program in Kamchatka, Russia in September 2005 a step was taken to vitalize and coordinate the many efforts to advance economic mineral recovery systems worldwide. The US Department of Energy is helping to spur on the interest and research needed to realize the many benefits of extracting minerals from geothermal solutions. The excitement of recovery of minerals from geothermal brines has many positive angles. The economics of certain geothermal site is improved if a revenue is arrived from a sellable commodity with the geothermal power. The use of cleaner geothermal brines also improves the capable use of the brine before reinjection. We will review the history of Geothermal in the USA and the opportunities for recovery of different minerals and the markets for them.

Jan 1, 2006

By W. H. Jay

Sulphide-containing minerals, particularly iron, lead to acid formation. In turn, the acid generates effluents such as copper acid drainage (AMD). The Berkeley Pit in Butte, Montana, USA and Mt Lyell in Tasmania, Australia, represent just two of many sites throughout the world for which acceptable treatment methods are required. In the gold cyanidation process, the presence of copper creates both a significant cost impediment and a potential environmental hazard. The tailings dam failure at Baia Mare in Romania which led to the release of copper and zinc cyanides created a major environmental disaster. The application of non-toxic water soluble polymers and ion exchange resins to selectively recover copper from AMD solutions, and the in-plant treatment of copper cyanide solutions and slurries to recover copper and recycle cyanide to prevent cyanide entering the tailings impoundment will be discussed. The economics of the various processes will be highlighted.

Jan 1, 2003

By Kurt Westerlund

Three years operating experience of the FLUXFLOW waste heat boiler (WHB) 20.000 nm3/0h at Boliden Rönnskär Sweden on a TBRC smelting galena (PbS). Operating experience from the Kivset flash WHB 11.900 nm3/h at Samim, Porto Vesme, Sardinia, Italy. Conceptual features of the 93.600 nm3/h FLUXFLOW (WHB) on the Isasmelt smelting in melt furnace for 180.000 t Cu/a at Mount Isa, Australia.

Jan 1, 1992

By Bernhard J. Ralph

In refractory gold ores much of the gold occurs in sub-microscopic form in sulfide minerals, most commonly pyrite and arsenopyrite Bacterial leaching is being developed as a pretreatment for these minerals to aid the liberation of gold and a variety of extracting reagents. This paper reviews the nature of the principal micro-organisms involved, the effects of various physico-chemical factors on the rate and extent of extraction, and likely mechanisms involved.

Jan 1, 1989

By Jr. Pomykala, B. J. Jody, E. J. Daniels

Each year, about five (5) million ton of shredder residues are landfilled in the United States. ·Similar quantities are landfilled in Europe and the Pacific Rim. Landfilling of these residues results in a cost to the existing recycling industry and also represents a loss of material resources that are otherwise recyclable. In this paper, we outline the resources recoverable from typical shredder residues and describe technology that we have developed to recover these resources.

Jan 1, 2000

By M. Cassir

"The unique properties of molten carbonates offer a large scope of applications in the field of energy. In effect, these molten salts are in the center of chemical and electrochemical reactions involving carbon and carbonaceous species, carbon dioxide and carbon monoxide, significant for energy generation or even for the production of fuels. Moreover, such media have also an oxidative character; they dissolve molecular oxygen and oxygen reduced species, O 2-, O22- and hypothetically o-, which may have an important role in waste treatments, homogeneous catalysis and synthesis of oxides. In this presentation, an overview will be given on the principal physicochemical properties of molten carbonates, before focusing on their main known application, the molten carbonate fuel cell (MCFC). Progress in other new fuel cells applications will also be analyzed, such as direct carbon fuel cell (DCFC), hybrid carbon fuel cell (HDCFC) and composite high-temperature fuel cells combining the features of MCFC and solid oxide fuel cell (SOFC). Afterwards, membranes for the separation and capture of C02 will be reviewed. Finally, other topics, as the oxidative coupling of methane in molten carbonates, will be briefly mentioned.IntroductionIn the thirty past years, the molten carbonate science and advances have been mainly dedicated to the understanding and optimization of the molten carbonate fuel cell (MCFC), which is still a major issue in the heart of a new vision of energy development. More recently, new topics related to other kinds of fuel cells (DCFC, composite SOFC/MCFC systems) and C02 capture have emerged and are concentrating important research and technological efforts. Moreover, new fields of implementation, related to molten carbonates, are also present: geology, glasses, production of nanocarbon particles etc. Considering other areas where this molten phase plays a major role, such as catalysis, waste destruction, surface treatment, it can be confirmed that the field of molten carbonates is very rich and offers many opportunities for fundamental science and competitive applications. Whatever their specific application, molten carbonates activity is associated to more efficient energy systems with low production of C02 and, in a prospective sense, to non-polluting energy using the value of C02. A recent event, the International Workshop on Molten Carbonates & Related Topics, IWMC201 I, held in Paris in 2011 , have put in evidence the importance to improve and exploit this investigation and technological domain."

Jan 1, 2012