| Abstract | Električni i elektronički (EE) otpad je trenutno najbrže rastuća kategorija otpada u svijetu.
Katodne cijevi (CRT) se zbog razvitka tehnologije zamjenjuju sa zaslonima koji koriste
tehnologiju tekućih kristala (eng. Liquid Crystal Displays – LCDs) koja se koristi kao
temeljna komponenta u većini potrošačke elektronike, uključujući televizore, osobna
računala, prijenosna računala, tablet računala, pametne telefone, navigacijskim
sustavima i sl. Otpadni LCD zasloni sadrže vrijedne komponente koje se mogu reciklirati
stoga je svrha ovog doktorskog rada utvrditi mogućnost korištenja otpadnih LCD-a kao
zamjena za pijesak u proizvodima od betona te kao potencijalni izvor elemenata kao što
su indij (In), nikal (Ni), krom (Cr), cink (Zn), olovo (Pb), aluminij (Al) i arsen (As) u skladu
sa zahtjevima kružnog gospodarstva, čime bi se zatvorio krug u recikliranja otpadnih LCD
zaslona.
Eksperimentalni postupak uključivao je usitnjavanje LCD zaslona na različite granulacije
(10 mm, 10 x 10 mm i 15 x 15 mm), izluživanje kiselim otopinama uz primjenu ultrazvuka
i uz primjenu mehaničkog miješanja kroz tri različita vremenska razdoblja (20 minuta, 40
minuta i 60 minuta) i kod tri različite temperature (20oC, 40oC i 60oC) te procjenu
izluživanja navedenih elemenata kako bi se odredili optimalni uvjeti za dobivanje
maksimalnih kapaciteta izluživanja. Ispitivani elementi pokazali su različita ponašanja pri
izluživanju, indij je pokazao postotak izluživanja (97,92%), dok su postoci izluživanja Ni,
Cr, Zn, Pb, Al i As također bila prihvatljiva u rasponu od 58,84% do 99,29% ali zbog
njihovog niskog sadržaja u LCD-ima recikliranje je upitno.
U provedenim istraživanjima je 1%, 5% i 10% finog agregata (pijesak) u betonu
zamijenjeno s usitnjenim LCD granulacije 10 mm koji je prethodno obrađen otopinom
(HCl: HNO3 = 3:1) u odnosu na kontrolnu smjesu betona (klasa C20/25). Ista zamjena je
provedena i s usitnjenim LCD-om koji nije obrađen. Ispitivanja upotrebljivosti dobivenih
betonskih proizvoda provedena je na industrijskoj razini. Rezultati pokazuju da su 1% i
5% odgovarajući postoci zamjene, odnosno zadovoljavaju zahtjeve za slijeganjem i
poboljšavaju čvrstoću i trajnost betona te se mogu koristiti kao reciklirani materijal u
betonskim primjenama. Navedenim postupcima recikliranja dobivaju se proizvodi s
dodanom vrijednosti i otpad se pretvara u sirovinu. |
| Abstract (english) | Electrical and electronic (EE) waste is currently the fastest growing waste category in the
world. Due to the development of technology, cathode ray tubes (CRT) are being replaced
by displays that use liquid crystal technology (Liquid Crystal Displays - LCDs), which are
used as a basic component in most consumer electronics, including televisions, personal
computers, laptops, tablet computers, smartphones telephones, navigation systems, etc.
Waste LCD screens contain valuable components that can be recycled, therefore the
purpose of this doctoral thesis is to determine the possibility and justification of using
waste LCDs as a substitute for sand in concrete products and as a potential source of
elements such as indium ( In), nickel (Ni), chromium (Cr), zinc (Zn), lead (Pb), aluminum
(Al) and arsenic (As) and in accordance with the requirements of the circular economy,
which would close the recycling process of waste LCD screens. The experimental
procedure included shredding the LCD screen into different granulations (10 mm, 10 x 10
mm and 15 x 15 mm), leaching with acid solutions using ultrasound and using mechanical
stirring for three different time periods (20 minutes, 40 minutes and 60 minutes ) and at
three different temperatures (20°C, 40°C and 60°C) and evaluation of the leaching of the
mentioned elements in order to determine the optimal conditions for obtaining maximum
leaching capacities. The tested elements showed different leaching behaviors, indium
showed a leaching percentage (97,92%), while the leaching percentages of Ni, Cr, Zn,
Pb, Al and As were also acceptable in the range from 58.84% to 99.29 % but due to their
low content in LCDs, recycling is questionable. In the conducted research, 1%, 5% and
10% of fine aggregate (sand) in the concrete was replaced with crushed LCD granulation
of 10 mm, which was previously treated with a solution (HCl: HNO3 = 3:1) compared to
the control mixture of concrete (class C20/ 25). The same replacement was performed
with a chipped LCD that was not processed. Tests of the usability of the obtained concrete
products were carried out at the laboratory and industrial level. Tests of the usability of
the obtained concrete products were carried out at the industrial level. The results show
that 1% and 5% are appropriate replacement percentages, that is, they meet the
requirements for settlement and improve the strength and durability of concrete and can
be used as recycled material in concrete applications. The mentioned recycling
procedures produce products with added value and turn waste into raw materials. |
