1,721,119 research outputs found
Eddy current separation of fine non-ferrous from bulk streams
No full textRecovery of fine non-ferrous metals from waste streams is a notoriously difficult problem in eddy current separation technology. Existing processes either have a low capacity or an incomplete recovery for particle sizes below 5mm. In a new process, the particles are fed slightly wet to make them stick to the surface of the conveyor belt. The action of the magnet rotor makes the non-ferrous particles tumble, so that they break loose from the belt and end up in front of the rotor. The new process combines a relatively high capacity with an almost complete recovery, even for heavy and poorly conducting non-ferrous metals
Modeling the throw of metals and non-metals in eddy current separations
No full textThe trajectories of real scrap particles processed with an eddy current separator are compared to computer simulations to investigate the effects of particle shape and particle – particle interaction, effects that are difficult to catch in a purely theoretical model. The results show that the primary particle parameters are size, conductivity and initial orientation, provided that the size of a particle is defined in relation to the eddy current process. Therefore, the detailed shape of scrap particles is less important. The effects of particle–particle interaction on the grade and recovery can be predicted by considering two different types of collisions between nonferrous and nonmetal particles. This results in a simple theory that can be incorporated into a simulation model
Settling behaviour of shredded plastic particles in jigging separation
No full textJigging has been a well-known gravity technique for concentrating ores and minerals for centuries. Now it is adapted to process shredded post-consumer plastic mixtures, too. As the density of water is within the density range of plastics, two distinct jig designs are needed to process all types of plastic mixtures. For plastics that are heavier than water, such as mixtures of ABS and PMMA, a jigging process similar to that employed in minerals processing can be used. However, when the components of the plastic mixture to be separated are lighter than water, e.g. mixtures of PE and PP, a novel inverse jigging process has to be applied. In both types of plastics jig, a separate discharge of the segregated layers can best be achieved using a ragging. Ragging action is here different from known types of mineral jig, because ragging in plastics jigs greatly influences the segregation process. This paper describes basic designs of plastics jigs. In addition, the settling behaviour of plastic particles and ragging bodies during jigging is discussed
High purity polyolefins recycling by melt separation
No full textPost-consumer wastes, such as WEEE (Waste from Electric and Electronic Equipment), HW (Household Waste) and ASR (Automotive Shredder Residue), can be considered an important resource of polyolefins. Such wastes are composed of a complex mixture of different materials. Recoverable high purity polyolefins are difficult to select mainly for two reasons: i) the complexity of the waste mixtures, characterized by the presence of different polymers and other polluting materials (wood aluminium, copper, stone, glass, etc), ii) the similar physical attributes (density) of potypropylene (PP) and polyethylene (PE). A new quality control strategy has been developed, based on the different melting points of the two target polyolefin's (PP and PE). In particular, an innovative and specialized device has been designed and realized. Several tests have been carried out according to different process parameters in order to define the best operative conditions to realize PE and PP recognition and separation. The results showed that this technique can be successful in the quality control of the purity of PP and PE flow streams
Upgrading of PVC rich wastes with the combination of magnetic density separation and hyperspectral imaging analysis
No full textPolyvinylchloride (PVC) is one of the most produced polymers in Europe, with a share of 11% in terms of mass (8 Million tonnes) of total polymer consumption, but in 2010 only 5% of the total PVC production was from recycled materials, where other polymer recycling achieves a level of 15% on average. In order to find an innovative process to extract PVC from window frames waste, a combination of two recent technologies has been tested: magnetic density separation (MDS) and hyperspectral imaging (HSI) analysis. By its nature, MDS is a flexible high precision density separation that is applicable to any mixture of polymers and contaminants with non-overlapping densities. As PVC has a very distinctive high density, this technology can be used to make high-grade PVC pre-concentrates from many PVC-rich waste streams. Considering that PVC has a characteristic spectral signature in the NIR range, it can be clearly discriminated from other polymers and contaminants by HSI. The results showed that the combined application of MDS and HSI techniques allowed to separate and identify PVC from window frame waste
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Get PDF“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
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