64 research outputs found

    All auto shredding: evaluation of automotive shredder residue generated by shredding only vehicles.

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    A well developed infrastructure exists for the reuse and recycling of automotive parts and materials. At the end of a vehicle's useful life many parts are removed and sold for reuse and fluids are recovered for recycling or proper disposal. What remains is shredded, along with other metal bearing scrap such as home appliances, demolition debris and process equipment, and the metals are separated out and recycled. The remainder of the vehicle materials is call shredder residue which ends up in the landfill. As energy and natural resources becomes more treasured, increased effort has been afforded to find ways to reduce energy consumption and minimize the use of our limited resources. Many of the materials found in shredder residue could be recovered and help offset the use of energy and material consumption. For example, the energy content of the plastics and rubbers currently landfilled with the shredder residue is equivalent to 16 million barrels of oil per year. However, in the United States, the recovered materials, primarily polymers, cannot be recycled due to current regulatory barriers which preclude the re-introduction into commerce of certain materials because of residual contamination with substances of concern (SOCs) such as polychlorinated biphenyls (PCBs). The source of the PCBs is not well understood. Old transformers, capacitors, white goods and ballasts from lighting fixtures are likely contributing factors. The project was designed to evaluate whether vehicles of varying age and manufacturing origin contribute to the PCB content in shredder residue. Additionally, the project was designed to determine if there are any trends in material composition of the shredder residue from varied age and manufacturing groups. This information would aid in future material recovery facility strategy and design. The test utilized a newly installed shredder plant to shred four categories of automobiles. The categories were defined by vehicle age and the manufacturing company and location. Each category of vehicles was processed individually through the shredder plant and the resulting shredder residue was analyzed for its materials composition and presence of PCBs and leachable metals. The results show that shredder residue from all vehicle categories tested are not significant contributors of PCBs and leachable metals. It was evident that leachable cadmium levels have decreased in newer vehicles. The composition of the shredder residue from each of the four categories is similar to the others. In addition, these compositions are approximately equal to the composition of typical shredder residues, not limited to automotive materials

    End-of-life vehicle recycling : state of the art of resource recovery from shredder residue.

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    Each year, more than 25 million vehicles reach the end of their service life throughout the world, and this number is rising rapidly because the number of vehicles on the roads is rapidly increasing. In the United States, more than 95% of the 10-15 million scrapped vehicles annually enter a comprehensive recycling infrastructure that includes auto parts recyclers/dismantlers, remanufacturers, and material recyclers (shredders). Today, over 75% of automotive materials, primarily the metals, are profitably recycled via (1) parts reuse and parts and components remanufacturing and (2) ultimately by the scrap processing (shredding) industry. The process by which the scrap processors recover metal scrap from automobiles involves shredding the obsolete automobile hulks, along with other obsolete metal-containing products (such as white goods, industrial scrap, and demolition debris), and recovering the metals from the shredded material. The single largest source of recycled ferrous scrap for the iron and steel industry is obsolete automobiles. The non-metallic fraction that remains after the metals are recovered from the shredded materials - commonly called shredder residue - constitutes about 25% of the weight of the vehicle, and it is disposed of in landfills. This practice is not environmentally friendly, wastes valuable resources, and may become uneconomical. Therefore, it is not sustainable. Over the past 15-20 years, a significant amount of research and development has been undertaken to enhance the recycle rate of end-of-life vehicles, including enhancing dismantling techniques and improving remanufacturing operations. However, most of the effort has been focused on developing technology to separate and recover non-metallic materials, such as polymers, from shredder residue. To make future vehicles more energy efficient, more lightweighting materials - primarily polymers, polymer composites, high-strength steels, and aluminum - will be used in manufacturing these vehicles. Many of these materials increase the percentage of shredder residue that must be disposed of, compared with the percentage of metals that are recovered. In addition, the number of hybrid vehicles and electric vehicles on the road is rapidly increasing. This trend will also introduce new materials for disposal at the end of their useful lives, including batteries. Therefore, as the complexity of automotive materials and systems increases, new technologies will be required to sustain and maximize the ultimate recycling of these materials and systems. Argonne National Laboratory (Argonne), the Vehicle Recycling Partnership, LLC. (VRP) of the United States Council for Automotive Research, LLC. (USCAR), and the American Chemistry Council-Plastics Division (ACC-PD) are working to develop technology for recovering materials from end-of-life vehicles, including separating and recovering polymers and residual metals from shredder residue. Several other organizations worldwide are also working on developing technology for recycling materials from shredder residue. Without a commercially viable shredder industry, our nation and the world will most likely face greater environmental challenges and a decreased supply of quality scrap, and thereby be forced to turn to primary ores for the production of finished metals. This will result in increased energy consumption and increased damage to the environment, including increased greenhouse gas emissions. The recycling of polymers, other organics, and residual metals in shredder residue saves the equivalent of over 23 million barrels of oil annually. This results in a 12-million-ton reduction in greenhouse gas emissions. This document presents a review of the state-of-the-art in the recycling of automotive materials

    An Indium Tin Oxide Electrode Modified With Gold Nanorods For Use In Potential-Controlled Surface Plasmon Resonance Studies

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    The modification of electrodes with gold nanoparticles results in an increased electrode surface area, enhanced mass transport, and improved catalytic properties. We have extended this approach to indium tin oxide (ITO) electrodes to obtain optically transparent gold nanorod-modified electrodes which display enhanced electrochemical capabilities and have the additional advantage of showing a tunable surface plasmon resonance. The procedures for attaining high surface coverage (15 gold nanorods per square μm) of such electrodes were optimized, and the potential-dependent surface plasmon resonance was studied under controlled electrical potential. In an exemplary sensor application, we demonstrate the detection of mercury via potential-dependent formation of an Au-Hg amalgam. [Figure not available: see fulltext.] © 2013 Springer-Verlag Wien

    Carbon Isotope Composition of Nighttime Leaf-Respired CO2 in the Agricultural-Pastoral Zone of the Songnen Plain, Northeast China

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    Variations in the carbon isotope signature of leaf dark-respired CO2 (δ13CR) within a single night is a widely observed phenomenon. However, it is unclear whether there are plant functional type differences with regard to the amplitude of the nighttime variation in δ13CR. These differences, if present, would be important for interpreting the short-term variations in the stable carbon signature of ecosystem respiration and the partitioning of carbon fluxes. To assess the plant functional type differences relating to the magnitude of the nighttime variation in δ13CR and the respiratory apparent fractionation, we measured the δ13CR, the leaf gas exchange, and the δ13C of the respiratory substrates of 22 species present in the agricultural-pastoral zone of the Songnen Plain, northeast China. The species studied were grouped into C3 and C4 plants, trees, grasses, and herbs. A significant nocturnal shift in δ13CR was detected in 20 of the studied species, with the magnitude of the shift ranging from 1‰ to 5.8‰. The magnitude of the nighttime variation in δ13CR was strongly correlated with the daytime cumulative carbon assimilation, which suggests that variation in δ13CR were influenced, to some extent, by changes in the contribution of malate decarboxylation to total respiratory CO2 flux. There were no differences in the magnitude of the nighttime variation in δ13CR between the C3 and C4 plants, as well as among the woody plants, herbs and graminoids. Leaf respired CO2 was enriched in 13C compared to biomass, soluble carbohydrates and lipids; however the magnitude of enrichment differed between 8 pm and 4 am, which were mainly caused by the changes in δ13CR. We also detected the plant functional type differences in respiratory apparent fractionation relative to biomass at 4 am, which suggests that caution should be exercised when using the δ13C of bulk leaf material as a proxy for the δ13C of leaf-respired CO2
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