Ecological risk assessment of heavy metals in coal gasification slags and their leaching toxicity

ABSTRACT

The coal gasification process produces a large amount of coal gasification slag (CGS), which accumulates heavy metals from the raw coal. The CGS not only occupies land resources during long-term storage but also poses potential ecological pollution risks. In this study, eight different CGS samples from various regions of China were analyzed to determine their chemical composition and evaluate their environmental risks. Two leaching methods recommended by the Ministry of Ecology and Environment of China were employed to conduct leaching experiments, aiming to assess the hazardous waste level of CGS. The results indicated that the risk index of YL-FS and XJ-CS reached 101.87 and 87.15, respectively, classifying them as medium-risk materials. The remaining samples were categorized as low-risk materials. CGS itself is not classified as hazardous solid waste. The leaching results revealed that the concentration of Be in the leaching solution of NMG-CS and XJ-CS exceeded 0.005 mg/L, placing them in Class II of general industrial solid waste. The remaining samples exhibited minimal leaching toxicity and were classified as Class I general industrial solid waste.

KEYWORDS:

• Coal gasification slag
• heavy metals
• potential risk assessment
• leaching toxicity
• solid waste

Disclosure statement

No potential conflict of interest was reported by the author(s).

Additional information

Funding

The authors gratefully acknowledge the financial support of the Strategic International Scientific and Technological Innovation Cooperation Funds of National Key R&D Program of China [No. 2021YFE0107300] and the Natural Science Basic Research Plan in Shaanxi Province of China (2021JC-03). Part of work was supported by the Science and Technology Major Project of China National Tobacco Corporation (110202101074(XX-19)) and the scientific research program of innovation platform in State Tobacco Monopoly Administration.