Papers by Keyword: Recycling

Abstract: Products by solid-state recycling of aluminum chips in hot extrusion process were controlled by temperature related parameters using preheating temperature 450 °C, 500 °C, and 550 °C for 1 hr, 2 hr, and 3 hr preheating time. By using Design of Experiments (DOE), the results found that the preheating temperature is more important to be controlled rather than the preheating time and increasing of temperature led to the high tensile strength. The profile extruded at 550 °C with 3 hr duration had gained the optimum case to get the maximum tensile strength. For the optimum case, heat treatment was carried out using quenching temperature at 530 oC for 2 h and aging process at 175 oC for 4 h. The tensile strength of extrudes specimen was improved significantly compared to those of non-treated specimen.

Abstract: Increasing waste streams of carbon fibers (CF) and carbon fiber reinforced plastics (CFRP) lead to increasing need for recycling and to growing amounts of recycled carbon fibers. A main issue in current research for carbon fiber recycling is the reuse of regained fibers. Carbon staple fibers such as recycled fibers hold big potential for mechanical properties of lightweight parts, if used properly. Applying recycled CF (rCF) as milled reinforcement fibers or as nonwoven in carbon fiber reinforced plastic leads to a poor yield of mechanical proper due to low fiber orientation, limitations in fiber volume content or due to short fiber length. The rC staple fiber tape presents a more efficient approach. Recycled carbon fibers are blended with 50 wt. % thermoplastic nylon 6 fibers and processed through a roller card to a sliver, which is a linear fibrous intermediate. The sliver is continuously drawn, formed, heated and consolidated to the thermoplastic rC staple fiber tape. The tape is similar to common carbon fiber tapes or to continuous tows but has different positive properties, such as high fiber orientation, homogeneous blend of fiber and matrix and suitability for deep drawing.

Abstract: Carbon fibre reinforced plastics (CRFP) are high performance materials with an outstanding lightweight potential. Recycling applications for production waste though, are still scarce and not fully established. In the CaroLIn (carbon fibre nonwovens optimised for aircraft interior components) research project a novel aerodynamic textile process is developed, in order to produce highly orientated non-wovens form recycled carbon fibres. In the first stage of the project a laboratory plant for the orientation of fibres has been constructed and implemented. Afterwards a process window has been defined and a number of process parameters identified. The influence of those parameters was then investigated, using the statistical design of experiment (DOE) method.

Abstract: Within the project ‘RecyCarb’ a qualified value-added chain for recycled carbon fibres (rCF) to enable their high-quality and sustainable re-use in sophisticated fibre-reinforced composites was established. A team of four industrial partners and two research institutes closed the technological gap between the actual rCF available on the market and the functional re-use as reinforcing elements in high-quality components. Process optimisation, initiation of a reliable scheme of quality assurance and a process integrated quality monitoring were the main aspects of this project. Besides different kinds of carbon fibre waste, different nonwoven processes (web formation and bonding methods) and an online fibre orientation analysis were investigated. This project focuses a variety of several application markets, e.g. sports equipment, medical technologies or automotive, shown by developed demonstrators.

Abstract: The control of degraded products, waste streams and secondary raw materials that can be produced from those must be in line with demand within the framework of an Advanced Circular Economy. Material requirements are developing dynamically depending on product development and consumer behavior. Accordingly, the recycling system must also behave dynamically and predictively and has to be transformed into stable, efficient but flexible process routes. This can also lead to a shift in the significance and sequence of the respective materials of main and secondary value in a process chain. This paper presents a novel approach for a smart and predictive circular economy. The approach consists of three major parts: An open information marketplace to meet information needs, suitable economic assessment and planning methods, and a dynamic optimization of the recycling process chain, e.g., selection of process steps and their sequence.

Abstract: Since several years, the lithium market is characterized by high growth rates especially due to the increasing demand for lithium-ion batteries. Therefore, the primary production is currently expanded and there is a growing interest in recycling. However, because of the chemical properties of lithium, many production processes lack efficient processes for the separation, concentration and purification of lithium. This article reviews the current use of liquid-liquid extraction (LLE) and chromatography in lithium production as well as research. Currently, the industrial application of LLE and chromatography in lithium purification is limited to the extraction of impurities and co-products. Extraction of lithium is only used as concentration step in few processes before lithium precipitation. In research and development, a wide variety of extractants and resins is investigated. In LLE, chelating extractants like crown ethers and calixarene and synergistic systems show the greatest potential. In the chromatographic separation the main focus of research lies upon cation exchange media, especially media with sulfonated ligands. However, most research is still in early development. Therefore, extensive research is needed to enable the industrial use of optimized LLE and chromatography processes in lithium production. Content TOC \o "1-3" \h \z \u HYPERLINK \l "_Toc515547308" Abstract PAGEREF _Toc515547308 \h 2 HYPERLINK \l "_Toc515547309" Content PAGEREF _Toc515547309 \h 3

Abstract: In the photovoltaic industry a total of 100,000 tons of silicon is lost as waste per year. This waste is originating from several cropping and sawing steps of the high purity silicon blocks and ingots during the solar cell wafer production, resulting in a silicon containing suspension. Among different approaches to recycle the silicon from this waste is the utilization of hydrocyclones, which can be used to separate or classify particles by weight and size. In this work the use of a hydrocyclone was evaluated to upgrade the silicon fraction from a typical sawing waste. A potential field of use for the recycled silicon particles might be as anode material for next generation lithium ion batteries.

Abstract: Transitioning from combustion engine-driven transportation to e-mobility demands a paradigm shift – from a system geared to maximize energy efficiency (i.e. fuel consumption) to a system that may be constrained by the availability of high technology (critical) metals required for electrical energy storage systems and drives. In the wake of these developments efforts in securing new resources of these metals from recycling of end-of-life products are increasing steadily.

Abstract: In the year 2016 alone, more than 1.35 billion smartphones were manufactured globally. These smartphones contain up to 60 different chemical elements and the summarized metal weight of the 2016 production may have well exceeded 50,000 metric tons. At present, most elements contained in this very complex “mixture” represented by a smartphone have recycling rates well below 50%, and the recycling rates of rare earths, indium, tantalum or gallium are even below 1%. The major challenge of mobile phone recycling is the complex composition of the devices made of many individual components – and the lack of transparent information as to the composition of these components. This is aggravated by the fact that many elements occur in traces only and / or are located in highly complex material composites. To enable more effective recycling of mobile phones, it is thus imperative to characterize the constituent components, the presence of elements in it, as well as their behavior during comminution. In a pilot study, a Nokia mobile phone Model 5228 Type RM-625, crushed with a granulator UG300, was examined by Mineral Liberation Analysis. The analysis of three particle size fractions of the comminuted material was carried out in an automated measurement mode with a grid of energy-dispersive X-ray spectra. A total of 130 different phases were detected during this analysis. More than 100 of these phases occur at levels <1% by weight. This strongly illustrates the very complex composition of smartphones. A comparison of the modal content of the three particle size fractions showed good liberation of certain components and an enrichment of some components in specific fractions. These observations reveal the potential to successfully separate different technical components from one another with the goal to increase the resource efficiency of the recycling process.

Abstract: Since the first synthesis of lithium iron phosphate (LFP) as active cathode material for lithium-ion batteries (LIB) in 1996, it has gained a considerable market share and further growth is expected. Main applications are the fast-growing sectors electromobility and to a lesser extend stationary energy storage. Despite increasing return flows, so far, little emphasis has been put on the recycling of LFP batteries due to the low content of high-value metals. In this study, current developments in the LFP battery market are presented. Furthermore, recycling processes for LIBs are reviewed and their applicability for LFP batteries is assessed. Currently, China is the main market for LFP batteries and rapidly increasing return flows are observed. In Europe and the USA, other battery chemistries are predominant. For LFP battery recycling, individually adaptable processes based on mechanical treatment of the cells followed by hydrometallurgical processing of the active cathode material seem to be the most promising approach. However, at present, these processes are only available at pilot scale, the profitability and their environmental performance are questionable. Therefore, further research addressing these challenges is urgently needed.