Possible Environmental Risks Associated with Steel Slag: A Batch Study

Batch studies are frequently used to understand the behavior of soils, sediments, and wastes exposed to different environmental conditions. This study exposed steel slag to 0.11 M acetic acid and a mixture of 0.128 M sodium dithionite, 0.3 M sodium citrate, and 0.1 M sodium bicarbonate extraction solutions. Steel slag is going to be used as a synthetic (top) soil for mine rehabilitation. Synthetic soil is an innovative and economical alternative method to dispose of industrial wastes and by-products. When used in mine rehabilitation, synthetic (top) soil would get exposed to different environmental conditions. Hence, understanding the behavior of slag under a range of soil conditions before its use as a synthetic soil is important. To understand the mobility of metal ions from steel slag under different environmental conditions, a batch study was performed on the end-over-end mixer at 30 rpm for 48 h. Results depicted that slag on being exposed to 0.11 M acetic acid and solution of 0.128 M sodium dithionite, 0.3 M sodium citrate, and 0.1 M sodium bicarbonate enhanced the mobility of heavy metals. In acidic conditions, metal concentration trend was Mn > Pb > Al > Ba > Cr > Zn > Ni > Cd > Cu and Mn > Al > Ba > Cr > Zn > Pb > Cu > Ni > Cd in sodium-rich (saline) conditions. Concentrations of Al, Ba, Cr, Fe, Mn, and Zn are more in saline conditions compared to acidic fractions. These results will assist in predicting the environmental impact and fate of toxic metals released into the system. This paper will discuss the possible reasons and environmental risks associated with steel slag used for synthetic soil.