| 1. |
- Forssberg, Eric, et al.
(author)
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Metals recycling from electronic scrap by air table separation : theory and application
- 1998
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In: EPD Congress 1998. - Warrendale, Pa. : Minerals, Metals & Materials Society. - 0873393880 ; , s. 497-515
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Conference paper (peer-reviewed)abstract
- Metals recovery from electronic scrap by physical separation may provide an alternative to the current recycling approach, through which halogenated flame retardants can result in hazardous dibenzo-p-dioxins and dibenzo-furans. On the basis of a complete sink-float analysis of personal computer and printed circuit board scrap, and in view of the advantages of dry processes for electronic scrap recycling by mechanical separation, air table separation is prioritized in an attempt to separate metals from plastics and glass involved. In the present paper, theoretical and practical considerations of air table separation have been detailed. It has been shown that air table separation is effective for recovering copper and precious metals from this specific waste stream. With the feed rate of 60 kg per hour, the combined grade and recovery of copper, gold, and silver attainable for the two heavy products produced by the air table used in the present study was shown in a table.
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| 2. |
- Menad, Nourreddine, et al.
(author)
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Thermodynamic conditions for the formation of dioxin during the recycling of non ferrous metals from electric and electronic scrap
- 1998
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In: EPD Congress 1998. - Warrendale, Pa. : Minerals, Metals & Materials Society. - 0873393880 ; , s. 657-673
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Conference paper (peer-reviewed)abstract
- Plastic materials have been associated with electric and electronic applications since the early days of the electrical industry. Plastics can amount to 30 percents of the scrap mass. Generally, they are treated with flame retardants such as halogenated ones and they can result in different toxic chemical compounds. These plastics can be used as combustibles in the recovery of copper and precious metals. However, during their combustion, halogenated flame retardants can produce dibenzo-p-dioxins and dibenzo-furans. The estimated thermodynamic data of several organic compounds resulting from combustion of electric and electronic scrap, have been used in conjunction with the program HSC to calculate the conditions for dioxin and furan formation. The results show that the formation of the dioxins is dependent on the quantities of carbon, hydrogen, chlorine and oxygen reacting in a given system, as well as on parameters such as temperature and pressure.
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| 3. |
- Rem, Peter C., et al.
(author)
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The investigation of separability of particles smaller than 5 mm by eddy-current separation technology - Part II: novel design concepts
- 2000
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In: Magnetic and Electrical Separation. - : Hindawi Limited. - 1055-6915 .- 1029-0303 .- 1477-2876. ; 10:2, s. 85-105
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Journal article (peer-reviewed)abstract
- Separability and separation mechanisms of small particles in modern rotating type eddy-current separators (ECSs) were discussed in Part I. In order to address problems associated with this design concept, a number of novel ECSs, each with a unique design, have been developed. Part II reports on investigation into the separability and separation principles for various materials smaller than 5 mm, including fine copper wires, in three new devices: the redesigned Delft vertical ECS (VECS), prototype TNO ECS and a laboratory wet ECS (WECS). It is found that TNO ECS and WECS are more practical tools for separation of small metal particles. In particular, WECS is able to recover approximately 80% of very fine copper wires, with 0.5 mm diameter and 2 mm length. Separation principles for WECS are discussed in greater detail than other design concepts in the present study. It appears that the fledgling WECS will be most promising in the future for processing small particles. Further, aluminum separation from the -10 mm fraction of electronic scrap has been carried out using TNO ECS. It transpires that both the recovery and the grade of the aluminum concentrate are superior to those obtained with the rotary belted-drum ECS of any type.
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| 4. |
- Zhang, Shunli, et al.
(author)
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Aluminum recovery from electronic scrap by High-Force R eddy-current separators
- 1998
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In: Resources, Conservation and Recycling. - 0921-3449 .- 1879-0658. ; 23:4, s. 225-241
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Journal article (peer-reviewed)abstract
- The amount of electronic scrap which contains a substantial portion of non-ferrous metals, primarily copper and aluminum, has been growing. The present study is directed toward aluminum recovery by a newly developed eddy current separator. The investigation on shredded personal computer and printed circuit board scrap demonstrates that the High-Force® eddy-current separator will be applicable for this purpose. It has been shown that, by a single pass of the materials on the High-Force® eddy-current separator, an aluminum concentrate out of personal computer scrap can be obtained with a purity of 85%, while maintaining a recovery in excess of 90%, with the feed rate being up to 0.3 kg/min.
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| 5. |
- Zhang, Shunli, et al.
(author)
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An investigation of the parameters of rotating drum type eddy current separators
- 1998
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In: Scandinavian journal of metallurgy. - 0371-0459 .- 1600-0692. ; 27:6, s. 253-260
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Journal article (peer-reviewed)abstract
- Rotating eddy current separators are increasingly used in waste processing industries, particularly in the automobile and electric scrap recycling, for recovery of non-ferrous metals. If misused, however, a substantial loss of the metal values can incur. A deeper understanding of the influences of a large number of parameters involved in the eddy current separation system is of great help in optimizing the performance of an eddy current separator. In the present study, a rotating drum-type High-Force eddy current separator, has been investigated extensively with a wide range of materials including aluminum, copper, brass, zinc, lead and polyvinyl chloride (PVC). The results obtained show that the material-related variables like particle size and shape play a critical role in maximizing the deflections of the metal particles, implying that an effective liberation of the materials to be recovered is crucial. Further, the machine-related variables like rotational frequency and positioning of the magnetic field are of great importance. It appears that, for a given conductor, the deflection is proportional to the rotational frequency of the magnetic field.
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| 6. |
- Zhang, Shunli, et al.
(author)
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Cable and wire scrap recycling by physical separation technologies
- 1998
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In: Environmental & Waste Management. - 1460-5147. ; 1:3, s. 189-202
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Journal article (peer-reviewed)abstract
- For cable and wire scrap recycling, physical separation technologies can offer a solution that is both environmentally friendly and economically viable. It is clear that such toxic emissions as hydrogen chloride and chlorine gases resulting from burning polyvinyl chloride (PVC) can be avoided, and that both metals and plastics can be recovered and reused. In this paper, physical separation techniques employed in the cable and wire scrap recycling industry throughout the world are described. A critical comparison of various separation techniques has been made. It appears that density-based separation techniques, in particular, air tables have been implemented extensively in this specific recycling industry world-wide. However, many other separation techniques capable of recycling cable and wire scrap have also been developed with a view towards improving separation selectivity (product quality), while maintaining a sufficient level of materials recovery. Of these, it seems that electrodynamic or high tension separation techniques remain to be developed by designing new electrode systems
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| 7. |
- Zhang, Shunli, et al.
(author)
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Current status of eddy current separation
- 1998
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In: Erzmetall. - 0044-2658. ; 51:12, s. 829-836
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Journal article (peer-reviewed)abstract
- The three-stage evolution of eddy current separation with the equipment and applications is critically analyzed in this paper, with the third stage of development highlighted. It can be concluded that the eddy current separators of generation III are associated with the development of the magnetic roll system design which includes the magnet configuration in a magnetic roll, the magnetic roll configuration in a separator, and the eddy current induction regimes. With a continuing improvement of the magnetic roll system design, it is expected that the eddy current separators of the next generation will be widely applied in the recycling industry.
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| 8. |
- Zhang, Shunli, et al.
(author)
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End-of-life electric and electronic equipment management towards the 21st century
- 2000
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In: Waste Management & Research. - : Wiley. - 0734-242X .- 1096-3669 .- 1399-3070. ; 18:1, s. 73-85
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Journal article (peer-reviewed)abstract
- With the rapid growth of the electronics industry and an evergrowing environmental awareness worldwide, an environmentally sound and economically viable management system for endoflife (EOL) electric and electronic equipment (EEE) is of great importance for sustainable development. Traditional recycling and processing of EOL electronics directed towards the recovery of copper and precious metals, will be faced with many challenges in the future. It has been recognized by the EOL EEE recycling industry that a new strategy for EOL EEE must be developed. In this paper, current status and future trends in EOL EEE management are presented. Selective dismantling of valuable and hazardous components is evaluated in terms of a graderecovery (GR) concept. It is concluded that selective dismantling and mechanical processing must be coordinated in such a way as to produce suitable materials for subsequent handling at the lowest cost. Furthermore, new developments in mechanical and thermal processing of EOL EEE are also discussed, which involve water table and eddy current separation techniques and reduction of dioxins and furans during combustion of the plastics containing halogenated flame retardants. In addition, the challenges and perspectives associated with EOL management of plastics and cathode ray tubes (CRTs) encountered in EOL EEE are highlighted in this paper. It is predicted that EEE, being designed for recycling in the 21st century, will be processed and recycled economically and ecologically on becoming obsolete.
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| 9. |
- Zhang, Shunli, et al.
(author)
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Intelligent liberation and classification of electronic scrap
- 1999
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In: Powder Technology. - 0032-5910 .- 1873-328X. ; 105:1, s. 295-301
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Journal article (peer-reviewed)abstract
- Mechanical recycling of electronic scrap oriented towards overall materials recovery from obsolete electronics is being implemented worldwide. The main reason is that the amount of electronic scrap is increasing and that the content of the precious metals present is decreasing. In this context, an effective liberation of various materials like metals and plastics is a crucial step towards mechanical separation. In addition, classification of electronic scrap is also important to be able to provide an appropriate feed material for the subsequent separation process. In the present study, liberation and its impact on the separation of personal computer (PC) scrap and printed circuit board (PCB) scrap has been investigated in detail. A special equipment functioning as a shape separator and an aspirator was used for the classification of electronic scrap.
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| 10. |
- Zhang, Shunli, et al.
(author)
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Investigation of separability of particles smaller than 5 mm by eddy current separation technology. Part I : Rotating type eddy current separators
- 1999
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In: Magnetic and Electrical Separation. - : Hindawi Limited. - 1055-6915 .- 1029-0303 .- 1477-2876. ; 9:4, s. 233-251
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Journal article (peer-reviewed)abstract
- Owing to the growing emergence of the end-of-life electrical and electronic products with complex material structures and an ever-diminishing particle size of the valuable metals involved, development of eddy current separators (ECS) has been targeting selective separation of small non-ferrous metal particles smaller than 5 mm. Separability of various materials smaller than 5 mm, including fine copper wires, has been investigated using ECS with various design concepts. The present research work is divided into two parts, with Part I focusing on the rotating type ECS which are today common in practice, and with Part II dedicated to the ECS with novel concepts such as wet ECS technology. In Part I, three rotating belted-drum ECS were employed, which are manufactured by Bakker Magnetics, the Netherlands, Huron Valley Steel Co., US, and Eriez Magnetics, UK respectively. It is found that the belted-drum ECS are effective for separating materials below 5 mm if the magnetic drum rotates in opposite direction to the conveyor belt. The separation principle, particularly the 'backward phenomenon' of the rotating type ECS for small particles has been unravelled in the present study. Moreover, separation of Al from the 0-10 mm fraction of electronic scrap has been conducted. The results obtained demonstrate that the belted-drum ECS with appropriate design may be applicable for separation of small aluminum particles from electronic scrap.
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