Search results for "Scrap"

Evaluating the material resource efficiency of secondary aluminium production: A Monte Carlo-based decision-support tool

2019

The contamination of aluminium streams during the different life cycle stages by alloy mixing and/or accumulation of foreign elements, in combination with the limited melt purification options during remelting, represents an important limiting factor in recycling. Consequently, in secondary aluminium production, primary aluminium is used to dilute the concentration of the residual elements, and alloying elements are added to adjust the composition to the target alloy specifications. However, adding elements, for which their refinement in a subsequent recycling step is problematic, results in permanent down-cycling or ‘quality losses’. Hence, it is crucial to more efficiently control the com…

Influence of Process Parameters on the Product Integrity in Friction Stir Extrusion of Magnesium Alloys

2016

Friction Stir Extrusion is an innovative direct-recycling technology for metal machining chips. During the process a specifically designed rotating tool is plunged into a cylindrical matrix containing the scraps to be recycled. The stirring action of the tool prompts solid bonding related phenomena allowing the back extrusion of a full dense rod. This process results to be particularly relevant because allows the reuse of the scrap without any previous treatment. Experiments have been carried out in order to investigate the influence of the process parameters on the extrudes quality and a numerical model has been developed in order to simulate the evolution of the material flow.

AZ31 magnesium alloy recycling through friction stir extrusion process

2015

Friction Stir Extrusion is a novel technique for direct recycling of metal scrap. In the process, a dedicated tool produces both the heat and the pressure to compact and extrude the original raw material, i.e., machining chip, as a consolidated component. A proper fixture was used to carry out an experimental campaign on Friction Stir Extrusion of AZ31 magnesium alloy. Variable tool rotation and extrusion ratio were considered. Appearance of defects and fractures was related to either too high or too low power input. The extruded rods were investigated both from the metallurgical and mechanical points of view. Tensile strength up to 80 % of the parent material was found for the best combina…

Al-SiC Metal Matrix Composite production through Friction Stir Extrusion of aluminum chips

2017

Abstract The production of most mechanical component requires machining operation, thus usually implying the cut material to be wasted as scrap. Traditional recycling techniques are not able to efficiently recycle metal chips because of some critical aspects that characterize such kind of scraps (shape, oxide layers, contaminating residues, etc). Friction Stir Extrusion is an innovative solid state direct-recycling technique for metal machining chips. During the process, a rotating tool is plunged into a hollows matrix to compact, stir and finally, back extrudes the chips to be recycled in a full dense rod. This process results to be particularly relevant since no preliminary treatment of t…

Aluminium sheet metal scrap recycling through friction consolidation

2019

Abstract In the last decades, several direct-recycling techniques have been developed and investigated in order to avoid material remelting, typical of the conventional aluminum alloys recycling processes. Moreover, the remelting step for aluminum recycling is affected by permanent material losses. Solid-state recycling processes have proven to be a suitable strategy to face such issues. Friction Consolidation is an innovative solid state-recycling technology developed for metal chips. During the process, a rotating die is plunged into a hollow chamber containing the material to be processed. The work of friction forces decaying into heat soften the material and, together with the stirring …

Soils from an iron and steel scrap storage yard remediated with aided phytostabilization

2018

Building capabilities among e-scrappers in informal electronic waste management: the case of the Nigerian e-scrappers

2016

This study examines the capabilities of e-scrappers developed through the constant interaction with electronic waste (e-waste). Video-based interviews were conducted with 29 male e-scrappers in Edo and Lagos States, Nigeria. Data analysis reveals that over time, e-scrappers in Nigeria are driven by aspirations not only of financial security but also of societal acceptance and recognition. Progressively, they have developed capabilities such as effective extraction methods based on individual abilities, market demand and the presence of an active social network, which have had a significant impact on the choices of the developed capabilities.

Développement d'un procédé électrochimique pour le recyclage du néodyme à partir de déchets électroniques

2018

Neodymium belongs to the lanthanide’s serie of the period system and is the key component of the permanent magnets Nd2Fe14B which are implemented in electronic devices and “green” technologies like wind turbines or electric cars and bicycles. Nowadays, only one percent of the neodymium in electronic scraps is recycled. Due to the geopolitical considerations and a strong increase of the use of permanent magnets, there is an impoverishment of the raw material resources leading to an instable market.Since some decades, few recycling processes have been developed on a lab scale without any upscaling to the industrial scale. The existing processes have several drawbacks like multiple steps to ob…

Definition of a laboratory optimization protocol for road bitumen improved with recycled tire rubber

2012

Abstract Bearing in mind the need to answer one of the most frequent needs for civil construction, in general, and major project such as road infrastructures in particular, this paper presents the results of a laboratory experimental study in order to evaluate the performance improvement that is possible to achieve when modifying road bitumen with CRM (Crumb Rubber Modifier) from discarded tire rubber (TR), using a Wet Process. The environmental advantage is double, since the aim of the research is to obtain high performance road bitumen thanks to the re-use of a discarded material, such as the rubber tires, which otherwise would be dumped in scrap-yard. In particular, this experimental stu…

Chlorinated phenolic compounds in coniferous needles. Effects of metal and paper industry and incineration

1997

Abstract Pine needles were analyzed for their contents of chlorinated phenolic compounds. Altogether about 30 samples from surroundings of a metal scrap plant, a pulp and paper mill, a hazardous waste incinerator and reference samples outside of the immediate influence of these were analyzed by GC/ECD and GC/MS. Most phenolic compounds in the needles were found to be bound to the plant material and were not extractable as such by organic solvents. The concentrations of some bound chlorinated phenolic compounds were on level of 1–300 ng/g in dried needle. For many compounds the concentrations were remarkably higher in the three years old needles compared to the concentrations in the one and …