ORIGINAL PAPER
Evaluation of the use of flotation for the separation of ground printed circuit boards
 
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1
Silesian University of Technology, Gliwice
2
Eskisehir Osmangazi University
3
University of Silesia, Katowice
CORRESPONDING AUTHOR
Dawid Marek Franke   

Silesian University of Technology, Gliwice
Submission date: 2021-11-24
Final revision date: 2022-01-16
Acceptance date: 2022-02-03
Publication date: 2022-03-23
 
Gospodarka Surowcami Mineralnymi – Mineral Resources Management 2022;38(1):171–188
 
KEYWORDS
TOPICS
ABSTRACT
The paper presents an assessment of flotation efficiency in the separation of plastics from metals derived from printed circuit boards (PCBs). The PCBs were ground in a knife mill prior to flotation. The contact angles of various materials corresponding to the grains from ground PCBs were measured, and a series of flotation tests was carried out to obtain the best product. The impact of the following parameters were investigated: the reagent and its dose, the airflow rate through the flotation tank and the feed concentration. The highest efficiency of metal recovery from PCBs was achieved for Dimethoxy dipropyleneglycol at a concentration of 157 mg/dm3 and with an airflow of 200 dm3/h and a feed concentration of <50 g/dm3. In the hydrophilic product (concentrate), it was mainly Cu (40%) and Sn (7.8%) that were identified by means of XRF, but there were also trace amounts of precious metals such as Au (0.024%), Ag (0.5797%) and Pd (149 ppm). Impurities in the form of Si (5%), Ca (3.2) and Br (2.1) were also identified in this product. Small amounts of metals in their metallic form were identified in the hydrophobic product (waste), mainly Cu (2.3), Al (1.7) and Sn (1.1). As a result of the research, high recovery ratios were obtained for Cu (93%), Sn (84), Ag (83) and Au (69). The purity of obtained metal concentrate with this method was lower in comparison with the other methods of the recovery of metals from ground PCBs for the same feed, i.e. electrostatic or gravity separation. Also considering other factors such as the environmental impact of the flotation process, the number of facilities and their energy consumption, this process should not be used in the developed metal recovery technology. Using electrostatic separation for the same feed obtained much better results.
ACKNOWLEDGEMENTS
Publication supported by the Silesian University of Technology, grant number: 06/050/BKM21/0122.
METADATA IN OTHER LANGUAGES:
Polish
Ocena zastosowania flotacji w odzysku metali z rozdrobnionych płyt obwodów drukowanych
płyty obwodów drukowanych, recykling, flotacja, odzysk, metale
W artykule przedstawiono ocenę zastosowania flotacji do rozdziału metali od tworzyw sztucznych z rozdrobnionych w młynie nożowym płyt obwodów drukowanych (PCBs). Zmierzono kąty zwilżania różnych materiałów odpowiadających ziarnom zmielonych PCBs oraz określono wypływy odczynników i ich stężeń, wydatków powietrza oraz zagęszczenia materiału na sprawność procesu flotacji. Najwyższą sprawność odzysku metali z PCBs uzyskano przy zastosowaniu eteru dimetylowego glikolu dipropylenowego w stężeniu 157 mg/dm3, wydatku powietrza 200 dm3/h i zagęszczeniu materiału poniżej 50 g/dm3. W produkcie hydrofilowym (metalach), wykorzystując metodę XRF, zidentyfikowano głównie Cu (40%) i Sn (7,8%) oraz śladowe ilości metali szlachetnych takich jak Au (0,024%), Ag (0,5797%) i Pd (0,015%). W produkcie tym rozpoznano również zanieczyszczenia takie jak Si (5%), Ca (3,2%) i Br (2,1%). W produkcie hydrofobowym (tworzywach sztucznych) występowały nieznaczne ilości metali, głównie były to Cu (2,3%), Al (1,7%) i Sn (1,1%). W wyniku przeprowadzonych badań uzyskano wysokie wskaźniki odzysku dla Cu (93%), Sn (84%), Ag (83%) i Au (69%). Niemniej jednak, w porównaniu do separacji elektrostatycznej, która była prowadzona dla tej samej nadawy, czystość produktów uzyskanych za pomocą flotacji była mniejsza. Biorąc pod uwagę również inne czynniki, między innymi takie jak oddziaływanie procesu flotacji na środowisko naturalne, ilość urządzeń oraz ich energochłonność, stwierdzono w konkluzji artykułu, że proces ten nie powinien być stosowany w tworzonej technologii odzysku metali z PCBs. Znacznie lepsze efekty rozdziału uzyskano bowiem dla tej samej nadawy, stosując proces separacji elektrostatyczny, który ma niewielki wpływ na środowisko przyrodnicze, a powstające produkty mogą być w pełni wykorzystywane.
 
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