TY - JOUR
T1 - Reduction of undesirable element leaching from fly ash by adding hydroxylated calcined dolomite
AU - Tian, Quanzhi
AU - Guo, Binglin
AU - Nakama, Shingo
AU - Zhang, Li
AU - Hu, Zhaochu
AU - Sasaki, Keiko
N1 - Funding Information:
This research was supported to KS by the JSPS (Japan Society for the Promotion of Science) Kaken Kiban A project (No. JP16H02435 ) and to QT by the China Scholarship Council (No. 201706420068 ). We would like to thank Professor Hu from China University of Geosciences for LA-ICP-MS measurements.
Publisher Copyright:
© 2019 Elsevier Ltd
PY - 2019/3/1
Y1 - 2019/3/1
N2 - Fly ash always contains many toxic elements which can be released into environment, thereby easily leading to environmental contaminations. In order to dispose fly ash safely, related strategies are needed. In this investigation, two kinds of hydroxylated calcined dolomites (HCD60 and HCD100) were used as the additives and compared with lime on the leachabilities of anionic species from fly ash. Both additives were found effective in reducing the leaching concentrations of these elements, which was better than that of only lime addition. Mg(OH) 2 and MgO were believed to play important roles in the hydration reaction of fly ash. In the presence of Mg(OH) 2 and MgO, there were more hydration products including calcium silicate hydrate, ettringite, hydrocalumite and other Layered double hydroxides (LDHs) generated which were effective candidates for anion removal. Thus, the final leaching results were controlled by these newly formed phases through adsorption, incorporation or encapsulation. On the other hand, compared with Mg(OH) 2 , MgO can promote the formation of hydration products in a larger extent because of the hydration process of MgO into Mg(OH) 2 . There was no systematic trend in the promotion of fly ash hydration by Mg(OH) 2 or MgO because it had a close relationship with the properties of original fly ash. Objectively, hydroxylated calcined dolomites can be promising candidate additives for reduction of toxic elements leaching from fly ash.
AB - Fly ash always contains many toxic elements which can be released into environment, thereby easily leading to environmental contaminations. In order to dispose fly ash safely, related strategies are needed. In this investigation, two kinds of hydroxylated calcined dolomites (HCD60 and HCD100) were used as the additives and compared with lime on the leachabilities of anionic species from fly ash. Both additives were found effective in reducing the leaching concentrations of these elements, which was better than that of only lime addition. Mg(OH) 2 and MgO were believed to play important roles in the hydration reaction of fly ash. In the presence of Mg(OH) 2 and MgO, there were more hydration products including calcium silicate hydrate, ettringite, hydrocalumite and other Layered double hydroxides (LDHs) generated which were effective candidates for anion removal. Thus, the final leaching results were controlled by these newly formed phases through adsorption, incorporation or encapsulation. On the other hand, compared with Mg(OH) 2 , MgO can promote the formation of hydration products in a larger extent because of the hydration process of MgO into Mg(OH) 2 . There was no systematic trend in the promotion of fly ash hydration by Mg(OH) 2 or MgO because it had a close relationship with the properties of original fly ash. Objectively, hydroxylated calcined dolomites can be promising candidate additives for reduction of toxic elements leaching from fly ash.
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U2 - 10.1016/j.wasman.2019.01.027
DO - 10.1016/j.wasman.2019.01.027
M3 - Article
C2 - 30902237
AN - SCOPUS:85060333953
SN - 0956-053X
VL - 86
SP - 23
EP - 35
JO - Waste Management
JF - Waste Management
ER -