Distribution, occurrence, and leachability of typical heavy metals in coal gasification slag

Yifan Zhang; Jiangshan Qu; Jianbo Zhang; Shaopeng Li; Wenfen Wu; Huiquan Li; Xinjuan Hou; Ruiqi Chang; Yanxia Guo

doi:10.1016/j.scitotenv.2024.172011

Distribution, occurrence, and leachability of typical heavy metals in coal gasification slag

Sci Total Environ. 2024 May 20:926:172011. doi: 10.1016/j.scitotenv.2024.172011. Epub 2024 Mar 30.

Authors

Yifan Zhang¹, Jiangshan Qu², Jianbo Zhang³, Shaopeng Li⁴, Wenfen Wu⁴, Huiquan Li², Xinjuan Hou², Ruiqi Chang², Yanxia Guo⁵

Affiliations

¹ State Environmental Protection Key Laboratory of Efficient Utilization Technology of Coal Waste Resources, Institute of Resources and Environmental Engineering, Shanxi University, Taiyuan 030006, China; CAS Key Laboratory of Green Process and Engineering, National Engineering Research Center of Green Recycling for Strategic Metal Resources, Institute of Process Engineering, Chinese Academy of Sciences, Beijing 100090, China.
² CAS Key Laboratory of Green Process and Engineering, National Engineering Research Center of Green Recycling for Strategic Metal Resources, Institute of Process Engineering, Chinese Academy of Sciences, Beijing 100090, China; School of Chemical Engineering, University of Chinese Academy of Sciences, Beijing 100049, China.
³ CAS Key Laboratory of Green Process and Engineering, National Engineering Research Center of Green Recycling for Strategic Metal Resources, Institute of Process Engineering, Chinese Academy of Sciences, Beijing 100090, China. Electronic address: zhangjianbo@ipe.ac.cn.
⁴ CAS Key Laboratory of Green Process and Engineering, National Engineering Research Center of Green Recycling for Strategic Metal Resources, Institute of Process Engineering, Chinese Academy of Sciences, Beijing 100090, China.
⁵ State Environmental Protection Key Laboratory of Efficient Utilization Technology of Coal Waste Resources, Institute of Resources and Environmental Engineering, Shanxi University, Taiyuan 030006, China. Electronic address: guoyx@sxu.edu.cn.

PMID: 38561128
DOI: 10.1016/j.scitotenv.2024.172011

Abstract

Coal gasification slag (CGS) contains variable amounts of heavy metals, which can negatively impact the environment. The mineral composition, element distribution, occurrence, and leaching characteristics of heavy metals in coal gasification coarse slag (CGCS) and coal gasification fine slag (CGFS) are studied to explain the leaching behavior of heavy metals in CGS. The movable components of heavy metals in CGFS (0.06 %-63.03 %) are significantly higher than those in CGCS (0 %-18.72 %). Leaching Environmental Assessment Framework 1313 data shows that heavy metals Zn, Cr, Cd, As, Pb, Ni, and Cu exhibit high leaching rates at low pH conditions, with Zn leaching concentrations as high as 2.11 mg/L at pH 2. Zn, Cr, and As exhibit obvious amphoteric leaching characteristics, and the leaching concentration of As at high pH (1.34 mg/L) even exceeds that at low pH (1.31 mg/L). Except for Cu, all heavy metals in CGS exceed the class III groundwater standard in some cases. Therefore, evaluation is needed before resource utilization of CGS due to potential leaching of some heavy metals.

Keywords: Coal gasification slag; Heavy metals; Leachability; Leaching environmental assessment framework; Occurrence.