TY  - JOUR
AU  - Stojković, Milica
AU  - Ristić, Mirjana
AU  - Đolić, Maja
AU  - Perić Grujić, Aleksandra
AU  - Onjia, Antonije
PY  - 2024
UR  - http://TechnoRep.tmf.bg.ac.rs/handle/123456789/7456
AB  - Considering the rising demand for rare earth elements (REEs), researchers are looking for new sources for their extraction, thereby fostering economic and environmentally justified processing solutions. Among potential industrial sources, coal fly ash emerges as one of the most promising. The recovery of REEs from coal fly and bottom ashes derived from different thermal power plants was the main focus of this study. A dual-step methodology was conducted on ash samples, which involved an ultrasonic roasting process to disintegrate the silica matrix, followed by a microwave-assisted acid leaching step to extract REEs. The roasting procedure was studied using the Plackett–Burman design, and the Box–Behnken design was subsequently implemented to optimize the leaching procedure. The optimized ultrasonic roasting procedure was set up at 95 °C for 10 min with an ash-to-roasting agent (3M NaOH) ratio of 0.5:1 (m/V). For acid leaching, the optimal conditions were obtained at 174 °C for 30 min with an HCl ÷ HNO3 mixture (1:1 V/V). The standard reference material (NIST 1633c) was used in the conclusive experiments to estimate the average recovery (80%) of REEs. The green aspects of this methodology were evaluated using several metrics (atom economy, E-factor, and energy consumption). The proposed process outperforms high-temperature roasting procedures in terms of greenness; however, the REE recovery rate is lower.
PB  - MDPI
T2  - Metals
T1  - Recovery of Rare Earth Elements from Coal Fly and Bottom Ashes by Ultrasonic Roasting Followed by Microwave Leaching
IS  - 4
SP  - 371
VL  - 14
DO  - 10.3390/met14040371
ER  - 

@article{
author = "Stojković, Milica and Ristić, Mirjana and Đolić, Maja and Perić Grujić, Aleksandra and Onjia, Antonije",
year = "2024",
abstract = "Considering the rising demand for rare earth elements (REEs), researchers are looking for new sources for their extraction, thereby fostering economic and environmentally justified processing solutions. Among potential industrial sources, coal fly ash emerges as one of the most promising. The recovery of REEs from coal fly and bottom ashes derived from different thermal power plants was the main focus of this study. A dual-step methodology was conducted on ash samples, which involved an ultrasonic roasting process to disintegrate the silica matrix, followed by a microwave-assisted acid leaching step to extract REEs. The roasting procedure was studied using the Plackett–Burman design, and the Box–Behnken design was subsequently implemented to optimize the leaching procedure. The optimized ultrasonic roasting procedure was set up at 95 °C for 10 min with an ash-to-roasting agent (3M NaOH) ratio of 0.5:1 (m/V). For acid leaching, the optimal conditions were obtained at 174 °C for 30 min with an HCl ÷ HNO3 mixture (1:1 V/V). The standard reference material (NIST 1633c) was used in the conclusive experiments to estimate the average recovery (80%) of REEs. The green aspects of this methodology were evaluated using several metrics (atom economy, E-factor, and energy consumption). The proposed process outperforms high-temperature roasting procedures in terms of greenness; however, the REE recovery rate is lower.",
publisher = "MDPI",
journal = "Metals",
title = "Recovery of Rare Earth Elements from Coal Fly and Bottom Ashes by Ultrasonic Roasting Followed by Microwave Leaching",
number = "4",
pages = "371",
volume = "14",
doi = "10.3390/met14040371"
}

Stojković, M., Ristić, M., Đolić, M., Perić Grujić, A.,& Onjia, A.. (2024). Recovery of Rare Earth Elements from Coal Fly and Bottom Ashes by Ultrasonic Roasting Followed by Microwave Leaching. in Metals
MDPI., 14(4), 371.
https://doi.org/10.3390/met14040371

Stojković M, Ristić M, Đolić M, Perić Grujić A, Onjia A. Recovery of Rare Earth Elements from Coal Fly and Bottom Ashes by Ultrasonic Roasting Followed by Microwave Leaching. in Metals. 2024;14(4):371.
doi:10.3390/met14040371 .

Stojković, Milica, Ristić, Mirjana, Đolić, Maja, Perić Grujić, Aleksandra, Onjia, Antonije, "Recovery of Rare Earth Elements from Coal Fly and Bottom Ashes by Ultrasonic Roasting Followed by Microwave Leaching" in Metals, 14, no. 4 (2024):371,
https://doi.org/10.3390/met14040371 . .

TY  - JOUR
AU  - Janković, Andrija Z.
AU  - Ćujić, Mirjana R.
AU  - Stojković, Milica D.
AU  - Đolić, Maja B.
AU  - Živojinović, Dragana Z.
AU  - Onjia, Antonije E.
AU  - Ristić, Mirjana Đ.
AU  - Perić Grujić, Aleksandra A.
PY  - 2024
UR  - http://TechnoRep.tmf.bg.ac.rs/handle/123456789/7362
AB  - In this work, removal of heavy metals (Cr, Mn, Co, Ni, Cu, Zn, As, Cd, and Pb) from fly ash has been studied using acid leaching and wet oxidation methods. In parallel, microwave-assisted acid digestion was applied for determination of pseudo-total concentrations of heavy metals to estimate the leaching efficiency. Multivariate statistics (Pearson correlation, principal component analysis, and hierarchical cluster analysis) have shown two dominant groups of elements, depending on their characteristics and affinity towards the ash solid phase. Thus, Cr, Zn, Mn, Co, and Ni belong to the group I, while Pb, As, Cd, and Cu belong to the group II. It was demonstrated that the wet oxidation method was more suitable than acid leaching since the reduction in metal concentration was 30 to 75 % compared to 12 to 25 % obtained by acid digestion. The influence of fly ash treatment on the residue characteristics was investigated by X-ray diffractometry and scanning electron microscopy. The analyses revealed surface and structure changes of fly ash after the wet oxidation treatment. Overall, wet oxidation could be an appropriate treatment for heavy metal removal from fly ash, providing a material that could be further used, thus reducing the risk of pollution caused by the disposal of coal combustion fly ash. © 2024, Association of the Chemical Engineers of Serbia.
AB  - Uklanjanje teških metala (Cr, Mn, Co, Ni, Cu, Zn, As, Cd i Pb) iz elektrofilterskog pepela proučavano je korišćenjem metoda kiselog luženja i vlažne oksidacije. Paralelno je primenjena i kisela digestija uz pomoć mikrotalasne pećnice za određivanje pseudoukupnih koncentracija teških metala u cilju procene efikasnosti luženja. Multivarijantna statistika (Pearsonova korelacija, analiza glavnih komponenti i hijerarhijska klaster analiza) pokazala je dve dominantne grupe elemenata u zavisnosti od njihovih karakteristika i afiniteta prema čvrstoj fazi pepela. Grupe I (Cr, Zn, Mn, Co i Ni) i II (Pb, As, Cd i Cu) su međusobno diskriminisane. Pokazalo se da je metoda vlažne oksidacije prikladnija od kiselog luženja jer je smanjenje koncentracija metala bilo 30-75 % u poređenju sa 12-25 % dobijenih kiselom digestijom. Takođe je ispitan uticaj tretmana letećeg pepela na karakteristike čvrstog ostatka metodama rendgenske difrakcije i skenirajuće elektronske mikroskopije. Ovim metodama su otkrivene promene na površini i u strukturi letećeg pepela nakon tretmana vlažnom oksidacijom. Vlažna oksidacija se može smatrati kao moguća metoda za tretman u cilju uklanjanje teških metala iz letećeg pepela, obezbeđujući materijal koji bi se mogao dalje koristiti i smanjujući rizik od zagađenja izazvanog odlaganjem letećeg pepela.
PB  - Savez hemijskih inženjera Srbije
T2  - Hemijska industrija
T1  - Impact of leaching procedure on heavy metals removal from coal fly ash
T1  - Uticaj metode izluživanja na uklanjanje teških metala iz letećeg pepela
EP  - 62
IS  - 1
SP  - 51
VL  - 78
DO  - 10.2298/HEMIND230901001J
ER  - 

@article{
author = "Janković, Andrija Z. and Ćujić, Mirjana R. and Stojković, Milica D. and Đolić, Maja B. and Živojinović, Dragana Z. and Onjia, Antonije E. and Ristić, Mirjana Đ. and Perić Grujić, Aleksandra A.",
year = "2024",
abstract = "In this work, removal of heavy metals (Cr, Mn, Co, Ni, Cu, Zn, As, Cd, and Pb) from fly ash has been studied using acid leaching and wet oxidation methods. In parallel, microwave-assisted acid digestion was applied for determination of pseudo-total concentrations of heavy metals to estimate the leaching efficiency. Multivariate statistics (Pearson correlation, principal component analysis, and hierarchical cluster analysis) have shown two dominant groups of elements, depending on their characteristics and affinity towards the ash solid phase. Thus, Cr, Zn, Mn, Co, and Ni belong to the group I, while Pb, As, Cd, and Cu belong to the group II. It was demonstrated that the wet oxidation method was more suitable than acid leaching since the reduction in metal concentration was 30 to 75 % compared to 12 to 25 % obtained by acid digestion. The influence of fly ash treatment on the residue characteristics was investigated by X-ray diffractometry and scanning electron microscopy. The analyses revealed surface and structure changes of fly ash after the wet oxidation treatment. Overall, wet oxidation could be an appropriate treatment for heavy metal removal from fly ash, providing a material that could be further used, thus reducing the risk of pollution caused by the disposal of coal combustion fly ash. © 2024, Association of the Chemical Engineers of Serbia., Uklanjanje teških metala (Cr, Mn, Co, Ni, Cu, Zn, As, Cd i Pb) iz elektrofilterskog pepela proučavano je korišćenjem metoda kiselog luženja i vlažne oksidacije. Paralelno je primenjena i kisela digestija uz pomoć mikrotalasne pećnice za određivanje pseudoukupnih koncentracija teških metala u cilju procene efikasnosti luženja. Multivarijantna statistika (Pearsonova korelacija, analiza glavnih komponenti i hijerarhijska klaster analiza) pokazala je dve dominantne grupe elemenata u zavisnosti od njihovih karakteristika i afiniteta prema čvrstoj fazi pepela. Grupe I (Cr, Zn, Mn, Co i Ni) i II (Pb, As, Cd i Cu) su međusobno diskriminisane. Pokazalo se da je metoda vlažne oksidacije prikladnija od kiselog luženja jer je smanjenje koncentracija metala bilo 30-75 % u poređenju sa 12-25 % dobijenih kiselom digestijom. Takođe je ispitan uticaj tretmana letećeg pepela na karakteristike čvrstog ostatka metodama rendgenske difrakcije i skenirajuće elektronske mikroskopije. Ovim metodama su otkrivene promene na površini i u strukturi letećeg pepela nakon tretmana vlažnom oksidacijom. Vlažna oksidacija se može smatrati kao moguća metoda za tretman u cilju uklanjanje teških metala iz letećeg pepela, obezbeđujući materijal koji bi se mogao dalje koristiti i smanjujući rizik od zagađenja izazvanog odlaganjem letećeg pepela.",
publisher = "Savez hemijskih inženjera Srbije",
journal = "Hemijska industrija",
title = "Impact of leaching procedure on heavy metals removal from coal fly ash, Uticaj metode izluživanja na uklanjanje teških metala iz letećeg pepela",
pages = "62-51",
number = "1",
volume = "78",
doi = "10.2298/HEMIND230901001J"
}

Janković, A. Z., Ćujić, M. R., Stojković, M. D., Đolić, M. B., Živojinović, D. Z., Onjia, A. E., Ristić, M. Đ.,& Perić Grujić, A. A.. (2024). Impact of leaching procedure on heavy metals removal from coal fly ash. in Hemijska industrija
Savez hemijskih inženjera Srbije., 78(1), 51-62.
https://doi.org/10.2298/HEMIND230901001J

Janković AZ, Ćujić MR, Stojković MD, Đolić MB, Živojinović DZ, Onjia AE, Ristić MĐ, Perić Grujić AA. Impact of leaching procedure on heavy metals removal from coal fly ash. in Hemijska industrija. 2024;78(1):51-62.
doi:10.2298/HEMIND230901001J .

Janković, Andrija Z., Ćujić, Mirjana R., Stojković, Milica D., Đolić, Maja B., Živojinović, Dragana Z., Onjia, Antonije E., Ristić, Mirjana Đ., Perić Grujić, Aleksandra A., "Impact of leaching procedure on heavy metals removal from coal fly ash" in Hemijska industrija, 78, no. 1 (2024):51-62,
https://doi.org/10.2298/HEMIND230901001J . .