Structure composition of coal gasification slag and speciation of main metals in coal gasification slag

The reduction, resource utilization and harmlessness of coal gasification slag are the hotspots of current research in the coal chemical industry. The study of physicochemical properties of coal gasification slag, alongside the content and environmental risk of embedded heavy metals, is the basis to achieve the above purposes. This thesis studied the structure composition and metal speciation of coarse slag and fine slag from a coal chemical industry in Ningdong Base, assessing the environmental risk of main metal elements they contained. The results showed that the coal gasification slag primarily consists of residual carbon and ash, the ash with the main components being SiO2 (50%) and Al2O3 (15%). The coarse slag has a high ash content (>90%) and its particles are dense and smooth, while the fine slag has a high residual carbon content (about 20%) and rich pores. Metals with contents above 500μg/g are mainly enriched in the coarse slag, whereas metals with contents below 200μg/g are enriched in the fine slag. The stability of metals in fine slag is lower than in coarse slag. The proportion of unstable state of Cd in the fine slag is over 70%, and the value of its risk evaluation index is 34.16, which leads to high environmental risk. This study aims to provide basic data for the resourcefulness and harmless treatment of coal gasification slag. © 2024 Chemical Industry Press Co., Ltd.. All rights reserved.