TY - JOUR
T1 - Enzymatically induced phosphate precipitation (EIPP) for stabilization/solidification (S/S) treatment of heavy metal tailings
AU - Han, Li Jun
AU - Li, Jiang Shan
AU - Xue, Qiang
AU - Guo, Ming Zhi
AU - Wang, Ping
AU - Poon, Chi Sun
N1 - Funding Information:
This work was financially supported by National Key Research and Development Programme (Grant No. 2019YFC1804002 ), International Partnership Program of Chinese Academy of Sciences (Grant No. 115242KYSB20200002 ), National Natural Science Foundation of China/Hong Kong Research Grants Council Joint Research Scheme (Grant No. 51861165104 ), the CAS Pioneer Hundred Talents Program in China, and the Open Research Fund of State Key Laboratory of Geomechanics and Geotechnical Engineering, Institute of Rock and Soil Mechanics, Chinese Academy of Sciences, China (Grant No. Z020012 ).
Publisher Copyright:
© 2021 Elsevier Ltd
PY - 2022/1/3
Y1 - 2022/1/3
N2 - The accumulation of heavy metal tailings has caused serious environmental and geological concerns. Therefore, treatment and recycling of heavy metal tailings have become urgent and vital. To this end, this paper proposes a biological solidification and stabilization (S/S) method, which applies enzymatically induced phosphate precipitation (EIPP) to strengthen Pb-Zn tailings and reduce the hazard of the heavy metals. The effectiveness and mechanism of EIPP-S/S have been systematically explored, including the effect of enzyme and reactant concentration, and tailings density on the treatment efficiency. The results showed that MgHPO4(H2O)3 (newberyite) and Pb9(PO4)6 were the main products of EIPP. The newberyite strengthened the tailings through connecting tailing particles and filling the pores, and the solidification effect was positively related to the reactant content and tailing compactness. The strength of the treated tailing sample could reach 2.7 MPa at a relative density of 90% with a reactant concentration of 1.5 M. After treatment, about 40% of Pb in the tailings changed from an acid-soluble state to oxidation state and residual state, as a result of the precipitation of Pb9(PO4)6. The concentration of leached Pb from the treated tailings under an acid rain environment was reduced from 0.86 mg/L before treatment to less than 0.02 mg/L, well below the limit of 0.1 mg/L in China's ground/surface water. This study provides new insights into the treatment and reuse of tailings by applying an innovative EIPP-S/S method, which can flexibly treat tailings in an environmentally friendly manner.
AB - The accumulation of heavy metal tailings has caused serious environmental and geological concerns. Therefore, treatment and recycling of heavy metal tailings have become urgent and vital. To this end, this paper proposes a biological solidification and stabilization (S/S) method, which applies enzymatically induced phosphate precipitation (EIPP) to strengthen Pb-Zn tailings and reduce the hazard of the heavy metals. The effectiveness and mechanism of EIPP-S/S have been systematically explored, including the effect of enzyme and reactant concentration, and tailings density on the treatment efficiency. The results showed that MgHPO4(H2O)3 (newberyite) and Pb9(PO4)6 were the main products of EIPP. The newberyite strengthened the tailings through connecting tailing particles and filling the pores, and the solidification effect was positively related to the reactant content and tailing compactness. The strength of the treated tailing sample could reach 2.7 MPa at a relative density of 90% with a reactant concentration of 1.5 M. After treatment, about 40% of Pb in the tailings changed from an acid-soluble state to oxidation state and residual state, as a result of the precipitation of Pb9(PO4)6. The concentration of leached Pb from the treated tailings under an acid rain environment was reduced from 0.86 mg/L before treatment to less than 0.02 mg/L, well below the limit of 0.1 mg/L in China's ground/surface water. This study provides new insights into the treatment and reuse of tailings by applying an innovative EIPP-S/S method, which can flexibly treat tailings in an environmentally friendly manner.
KW - Enzymatically induced phosphate precipitation (EIPP)
KW - Leaching
KW - Stabilization/solidification (S/S)
KW - Tailings
KW - Unconfined compressive strength
UR - http://www.scopus.com/inward/record.url?scp=85119097177&partnerID=8YFLogxK
U2 - 10.1016/j.conbuildmat.2021.125577
DO - 10.1016/j.conbuildmat.2021.125577
M3 - Journal article
AN - SCOPUS:85119097177
SN - 0950-0618
VL - 314
JO - Construction and Building Materials
JF - Construction and Building Materials
M1 - 125577
ER -