Search

Waste printed circuit boards (WPCBs) -- a common type of ewaste consisting of electronic components with a significant amount of rare and precious metals as well as glass fiber composites. The development of WPCB retreatment technology through mechanical methods, resulting in metallic and nonmetallic waste fractions, can be efficiently classified as enriched concentrate. The research presented in this paper highlights the potential trends for recycling WPCBs. The integration of impact milling for WPCBs is a promising technology for the partitioning and fragmentation of different components and for the separation of fractions. The mechanical sizereduction and separation technology of precrushed WPCBs, using direct and separative disintegrator milling, has been compared with other technologies (hammer milling and high voltage fragmentation). The main parameters, such as the specific energy (ES) of WPCB treatment and the rate of separation of different phases, were studied. As preliminary results show the optimal parameters of partitioning of the metallic and nonmetallic parts, fragmentation and delamination (specific energy of treatment and rate of separation) by disintegrator milling were proposed. [ABSTRACT FROM AUTHOR]

Good cementing properties, fast setting and strong thermal performance make calcium aluminate a valuable raw material for use in the production of different types of new refractory materials, e.g., heat conductive/storage materials. The main aim of the study was to determine thermal properties of novel Nb-slag based materials with different fillers, and to clarify the optimal composition and technology. The preparation process of the studied materials was the following: mixing of components, casting into moulds and hardening of materials. To estimate potential application areas, the following thermal properties of CA-based materials were investigated: thermal behaviour, the coefficient of thermal expansion (CTE) and conductivity. For thermal analysis, small cylindrical specimens were cut out from produced materials, and plates sized 25 × 300 × 300 mm were used for conductivity studies. Different compositions of CA-based materials, the hardening process, and the influence of mechanical activation on the strength were analysed. The best thermal properties similar to the analogous reference materials were obtained by quartz sand and granite sand as filler materials. The thermal conductivity of the novel CA-based material is 1.5 times higher and the bending strength is about 3 times higher compared to commercial thermoplates. [ABSTRACT FROM AUTHOR]

Copyright of Proceedings of the Estonian Academy of Sciences is the property of Teaduste Akadeemia Kirjastus and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Proceedings of the Estonian Academy of Sciences is the property of Teaduste Akadeemia Kirjastus and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Proceedings of the Estonian Academy of Sciences is the property of Teaduste Akadeemia Kirjastus and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)