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By Karel Van Acker

The automotive is a sector where energy consumption during the use phase prevails over the production and the end-of-life phase. Therefore, a lot of research and innovations at replacing classical steel parts by lighter materials like light metals and polymer composites. While composites are very attractive for the use phase of cars, their introduction suffers from the limited end-of-life options for composite structures. An extensive life cycle analysis for a reference car design has been conducted to study the effects of replacement of conventional steel structures by lightweight carbon fibre composite alternatives. The study also takes second order effects in the design of the car into account. The opportunities and treats of the trend towards more intensive use of carbon-fibre composites in car design are identified. A discussion on the potential of other types of composites for the automotive in terms of sustainability considerations is added.

Jan 1, 2010

By Yongbin Yang

Cathodic reduction of oxygen is a process involved in many fields. As is well known, the mechanism of oxygen reduction usually varies considerably with electrode substrates. In this paper, cathodic reduction of oxygen on gold electrode was studied by linear sweep voltammetry with regards to cyanide leaching of gold. As the results shows, the electron transfer number increases as potential shifted negatively and decreases as pH value increases. Besides, the increment of electron transfer number as a function of potential decreases when pH value increases. When pH increases to 13.0, the volt-ampere curve exhibits a relative flat section with currents approximate to the limit current density of a 2e process. By varying dissolved oxygen concentration, the electron transfer number was calculated for pH11.0 at different potentials, the results being 2.387e, 2.732e, 2.982e, and 3.227e at, -0.35V, -0.40V, -0.45V, and 0.50V, respectively. The calculated current densities are in good conformity with measured results.

Jan 1, 2010

By Leith Sharp

I was confronted with a profound dilemma as an undergraduate engineering student at the University of New South Wales in Australia in 1992. I had been taught that our planetary life-support systems were in a state of alarming decline by an institution that operated as if what the faculty was teaching was irrelevant. Lights were left on in empty overcooled classrooms, recycling bins were nonexistent, lawns were maintained using pesticides and herbicides, diesel trucks spewed fumes as they passed on their way to drop off chlorine-bleached virgin paper. This disconnect was very alarming to me. While it was obvious that universities should play a leading role in teaching and researching sustainability issues, I wondered how it could be possible to make widespread institutional changes to meet the demands of environmental sustainability when it was not even being done in the very university sector where these ideas were being promulgated. If universities would not change, then who can and who will, I wondered? To a growing number of people, the idea of teaching sustainability without demonstrating it is highly problematic. It is also widely believed that the ability of the higher education sector to reform its own practices is an important indicator of humankind?s ability to address the global environmental imperative across all sectors of society. These sentiments have helped fuel what is now referred to as the campus sustainability movement, a movement dedicated to transforming our campuses into living laboratories for the demonstration and practice of environmental sustainability.

Jan 1, 2010

By Jewel Andrew Gomes

Arsenic is considered as one of the toxic materials being controlled by Environmental Protection Agencies in several developed and developing countries. It is found in the nature as constituents of the soil, minerals and also in various organic forms. It enters the air, water, and land from wind-blown dust and gets into water from runoff, leaching, soil erosion and anthropogenically from chemicals used for wood preservation, insecticides, medicine, military purpose, pigments, and electronic circuitries. There are several techniques available for removal of Arsenic, such as coagulation/filtration, lime softening, ion exchange, reverse osmosis, nanofiltration, wet chemical, and electrochemical. Electrocoagulation has been found as one of the most efficient techniques to remove inorganic arsenic with more than 99% efficiency. In this paper, we present our work on electrochemical treatment of both the inorganic and organic arsenic from water using various sacrificial electrode materials, i.e., iron, aluminum, copper, and combination of them. The floc produced by this method has been also characterized using XRD, SEM/EDS, FTIR, and cyclic voltammetry.

Jan 1, 2010

By Manis Kumar Jha

Leaching studies were carried out for the recovery/ recycling of metals from PCBs containing 17.05% Cu, 0.74% Ni, 1.74% Fe, 4.35% Pb and 8.32% Sn using various acids such as H2SO4, HCl and HNO3. While sulfuric acid was not a suitable leachant for the dissolution of metals from PCBs, hydrochloric acid selectively dissolved tin. The nitric acid was found to be effective lixiviant with the recovery of 99.99% Cu, Fe, Ni and 36.7% Pb in 6M HNO3 at S/L ratio of 100 g/L and 90oC. The kinetic studies carried out with 2M and 4M HNO3 at 90oC showed ?Ash diffusion control dense constant size-spherical particles? model.

Jan 1, 2010

By Hebi Yin

A two-dimensional multi-scale solidification model was developed to study the heat transfer, fluid flow, and grain growth occurring in the molten pool during the laser engineered net shaping (LENS) process. This model coupled the finite element method to calculate mass, energy and momentum transport in the macroscale with the cellular automaton technique to calculate liquid/solid phase change at the microscale. The validation of the model was performed by comparing the simulation results with experimental data from previously published works, showing good agreement in temperature distribution and the dendrite morphology (size and shape). The simulation results showed that Marangoni convection, caused by the temperature gradient along the pool surface, played a critical role in determining the flow pattern in the molten pool and exerted influence on the pool size and shape. It was also found that columnar dendrites can be formed, with dendrite arm spacings as fine as a few microns due to the high cooling rate during the LENS process. In addition, the influence of fluid flow on the dendrite growth in the pool was discussed.

Jan 1, 2010

By A. Krishnan

Keywords: Tantalum extraction, SOM Technology, inert anode, membrane stability The Solid Oxide Oxygen Ion conducting Membrane (SOM) technology offers great potential for environment friendly and energy efficient extraction of high-energy content metals. This work was performed to demonstrate the technical and commercial viability of the technology to produce tantalum metal directly from tantalum oxide and ore concentrates using a solid-oxide, oxygen-ion-conducting membrane (SOM). The process can be used to efficiently produce tantalum metal without expensive pre-processing of raw materials and without harmful by products. The work reported in this paper is: the proof that high purity tantalum metal can be produced, study of the electrochemical behavior of the cell and the method to increase membrane stability.

Jan 1, 2005

By Preston C. Holloway

Transformational roasting involves the heating of a material along with specific additives to induce mineralogical changes in the starting material. By controlling the chemical composition, roasting atmosphere, temperature and time of reaction, the mineral transformations induced during roasting can be engineered to control the distribution of valuable, or harmful, metals and to produce new mineral assemblages that are more amenable to conventional methods of metals recovery or to environmentally safe disposal. To date, this type of process has only been applied to the recovery of a limited number of metals, but current research is looking to expand the application of these techniques to the recovery of metals from a wider range of materials. An introduction to these techniques is presented along with preliminary results from their application to metals recovery from zinc bearing wastes, such as zinc ferrite leach residues and carbon steel electric arc furnace dust.

Jan 1, 2006

By J. C. Pandey

The paper highlights the experimental investigations to characterize texture and plastic strain ratio r-Bar in auto grade steel sheets by ultrasonic measurements, whereas attempts were made to characterize interlamellar spacings in pearlite, tensile stresses and torsional properties in prestressed concrete wires by eddy current measurements. Good correlations were obtained between the testing parameters (such as ultrasonic attenuation and velocity in case of steel sheets as well as eddy current out put voltage and phase angle in case of steel wires) and the materials properties (such as texture, plastic strain ratio r-Bar, interlamellar spacings in pearlite, tensile stresses and torsional properties). 15 MHz normal direct contact and 20 MHz delay line normal shear wave probes were used for ultrasonic measurements. Eddy current measurements were done using an absolute coil probe with variable frequency selection. The experimental results show the possibility of nondestructive on line measurement of the above microstructures and properties.

Jan 1, 2010

By Hans Korfmacher

Product take-back regulations implemented in Europe have presented significant challenges to the consumer electronic product and battery industries. Initially companies established single compliance organizations within individual Member States. These programs met business needs but were inefficient and costly. They were protected from pressures of marketplace competition and could not leverage economies of scale. In order to address these problems P&G, Hewlett Packard, Sony and Electrolux conceived a pan-European compliance organization to collect waste electronic equipment Europe-wide. This organization, called the European Recycling Platform (ERP), operates in competition with existing national compliance systems. Since 2005 ERP has collected 800,000+ tons of waste electronic products and delivered millions of dollars in cost savings. This presentation reviews the steps needed to establish successful competitive collection organizations that provide sustainable recycling at the lowest cost.

Jan 1, 2010

By Godwin Beene

During recent years, copper and acid production from Nkana Smelter has formed a significant proportion of ZCCM's total output, but a number of problems affecting the smelter over the last decade have only been recently overcome. This paper discusses recent developments in the smelting practice, highlighting some of the operational problems experienced and associated solutions. The smelter performance over the decade is discussed and the innovations in the smelting technology employed to sustain production in the wake of limited re-capitalization are dealt with in detail.

Jan 1, 1999

By Gabrielle Gaustad

For aluminum, substitution of primary with secondary resources decreases energy consumption; this energy advantage creates a strong economic incentive to recycle. Several authors have raised concerns that the current sinks for secondary materials may soon be saturated, impeding subsequent expansion of recycling. This work combines dynamic material flow analysis with optimal batch planning models to quantify the significance and drivers of these pending limits under several scenarios, and thereby explore potential opportunities to increase recycling. An aluminum recycling system case was developed that includes containers and packaging, automotive, and construction products and scraps. The impacts on aggregate scrap utilization and materials cost are explored in the context of changing alloy demand and lifetime. Insights drawn from this specific case study could be applied to multi-stakeholder, systemic models.

Jan 1, 2010

By Shadia J. Ikhmayies

The SnO2/CdS/CdTe thin film solar cells were fabricated on glass substrates by using the spray pyrolysis (SP) technique for the deposition of the SnO2 and CdS layers and vacuum evaporation for the CdTe layer. The transmittance curves were used to investigate the interdiffusion in the two interfacial regions SnO2/CdS and CdS/CdTe by taking the first derivative of the absorbance as a function of wavelength. The appearance of new bandgaps around the bandgaps of SnO2:F, CdS:In and CdTe layers is a strong evidence on the interdiffusion in the two interfacial regions and/or the formation of quantum dots.

Jan 1, 2010

By Elsa Olivetti

Life cycle assessment (LCA) is used increasingly as a tool to provide quantitative metrics of environmental impact and inform early stage materials selection decisions. One common challenge in LCA stems from allocation of burden when multiple adjacent products share some of the same processes. A critical example of this is the partitioning of benefit or burden at product disposition in open-loop recycling scenarios. This work reviews the challenge of allocation and investigates the various methods proposed for allocating end-of-life (EOL) burden. Specifically this work examines whether these methods lead to different results and explores the trends in allocation method bias for or against particular materials classes.

Jan 1, 2010

By N. V. . Panishev

The Bakal (South Ural, Russia) deposit of iron ore bearing iron carbonate (siderite) with the capacity of more than 1 billion tones belongs to the MMK. This ore cannot be fully processed via blast furnace technology because of high content of MgO. According to the investigations carried out in the USA and Japan in 1999-2004 the ITmk3 (Ironmaking Technology mark three) RHF technology is a breakthrough in Ironmaking. Four iron ore types (hematite, magnetite, high and low Al2O3/SiO2) were tested. Reduction, melting and slag removal can be achieved in just 10 min. The main objective of the investigation is to establish optimum operation conditions for the production of iron nuggets from iron carbonate bearing ore via the ITmk3 by means of the lab scale testing. Samples of iron ore and carbon reductant were chemically and physically analyzed. Green pellets were processed via a lab tube furnace to simulate RHF conditions. The nuggets and slag were chemically analyzed. This preliminary test work provides valuable information which may be used for large-scale testing in a commercially sized RHF.

Jan 1, 2010

By Keith S. McIntosh

The fire assay process for the quantitative recovery of platinum group elements (PGE?s) prior to subsequent analysis traditionally is a time-consuming process. Samples derive from various ore types and contain PGE?s at the ppm or ppb levels, making concentration of the elements mandatory before assaying. Traditionally sample turn-around times are of the order of 24 hours. The whole sequence of sample preparation, fire assay and subsequent analysis of PGE?s have been automated by Anglo Platinum. Some of the major challenges on the road to automation will be discussed and the novel solutions that were implemented. The engineered solution included robotic automation of the whole sequence, from sample preparation, up to the final element by element assay. The final system allowed for rapid (less than one hour) and accurate analysis of PGE?s even in streams containing very low levels, such as flotation tailing streams and drill core samples.

Jan 1, 2006

By Seong- Rin Lim

Light-emitting diodes (LEDs) are regarded as environmentally friendly light sources due to their high energy efficiency and lack of mercury content. LEDs are used for a variety of domestic and commercial lighting systems, where they are replacing incandescent and fluorescent lamps at a rapid rate. Incandescent lamps inefficiently consume energy because electricity is mostly converted to heat rather than light. This causes unnecessary environmental impacts and energy consumption associated with power generation and transmission from a life cycle perspective. Although fluorescent lamps are more energy-efficient than incandescent lamps, their disposal at end-of-life presents special challenges because of the presence of toxic mercury. Despite the seemingly apparent advantages of LED, very few studies have rigorously addressed potential environmental consequences of their disposal. Specifically, LEDs are designed with III-V semiconductors that presumably consist of toxic and rare materials, including arsenic, gallium, and indium. We hypothesize that, depending on their concentrations and leachability, these constituents may also contribute to render LEDs as hazardous waste at the end of their useful life.

Jan 1, 2010

By Peter Ryan

A patented process for agglomeration of Smelter ESP dusts is described. Addition of suitable binders followed by compaction, transforms fine, difficult to handle material into a dry, flowable agglomerate suitable for plant reentry. Details for the agglomeration process metallurgy and laboratory pilot plant testing are discussed. An example of full scale plant operations is described.

Jan 1, 1999

By Jian Zhang

From the standpoint of quality, surface cracks normally pose more of a problem than internal cracks. Hypo-peritectic (HP) steel grades are well known for their proneness to surface longitudinal cracking (SLC) during continuous casting. This study analyzed the influences of chemical composition, technique parameter and secondary cooling on the surface longitudinal cracks. Based on the optimized the first and secondary cooling zone water distribution in the process of continuous casting, low cooling water distribution at solidification initial stages and uniform cooling at secondary cooling zone were suggested, which can be used to effectively control the surface longitudinal cracks.

Jan 1, 2010

By Hani Henein

Recent innovations in atomization of molten metals have occurred in the area of single fluid atomization. Impulse Atomization (IA), one of the single fluid techniques, provides unique capabilities to study different regimes of atomization in a controlled environment. By changing processing variables, a mono-dispersed distribution of droplets above one millimeter in diameter can be produced. This is accomplished through proper characterization of the forces influencing the process and in particular the flow of melt through the orifice. This paper will discuss the approach and illustrate results with molten aluminum and cobalt.

Jan 1, 2006