期刊
CONSTRUCTION AND BUILDING MATERIALS
卷 314, 期 -, 页码 -出版社
ELSEVIER SCI LTD
DOI: 10.1016/j.conbuildmat.2021.125577
关键词
Enzymatically induced phosphate precipitation; (EIPP); Stabilization; solidification (S; S); Tailings; Unconfined compressive strength; Leaching
资金
- National Key Research and Development Programme [2019YFC1804002]
- International Partnership Program of Chinese Academy of Sciences [115242KYSB20200002]
- National Natural Science Foundation of China/Hong Kong Research Grants Council Joint Research Scheme [51861165104]
- CAS Pioneer Hundred Talents Program in China
- Open Research Fund of State Key Laboratory of Geo-mechanics and Geotechnical Engineering, Institute of Rock and Soil Mechanics, Chinese Academy of Sciences, China [Z020012]
The study proposed a biological solidification and stabilization method using enzymatically induced phosphate precipitation to strengthen Pb-Zn tailings. Results showed that the EIPP-S/S method effectively reduced the leached concentration of lead in the tailings, mitigating environmental hazards.
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.
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