Study on leaching of electric arc furnace (EAF) slag for its sustainable applications as construction material

Abstract

The steel production generates approximately 10 % of electric arc furnace slag on the production of each ton of steel. In the view of environmental concerns and government regulations regarding slag disposal, alternate ways of its utilization are required. This work is focused on the leaching behaviour study of electric arc furnace (EAF) slag to assess its suitability as construction material. EAF slag contains toxic metals; consequently, their leachable quantity may affect the eco-system. Chromium (Cr), lead (Pb), mercury (Hg), molybdenum (Mo) and cadmium (Cd) have found special concern due to their high toxicity for human kind as well as for the environment. The leaching study of EAF slag was carried out through the application of sequential batch water leaching tests (SWLT), batch test and toxicity characteristics of leaching procedure (TCLP) method. Fresh EAF slag was characterized by XRF, XRD, SEM and ICPMS analysis for the determination of essential compositions and contamination. SWLT was performed at different pH of 4.0, 5.3, 6.1, 7.2 and 8.5. It was found that toxic metals was not leached beyond permissible limits at any pH. Moreover, TCLP method was applied for the leaching analysis of EAF slag at pH of 4.93 and 2.88. The concentrations of toxic metals in leachates were found negligible through ICP-OES analysis. The batch test method was also applied upto 60 days of EAF slag. This test was carried out at various pH ≈ 4, 5 and 6. The obtained leachates were tested at 10 days, 15 days, 30 days, 45 days and 60 days of leaching. The ICP-OES analysis of leachates showed negligible concentrations of leached metals/elements. Through the application of different leaching test methods, it was found that the leaching of hazardous heavy metals from EAF slag is negligible or within permissible limits as per IS 383−2016 and EPA. Therefore, EAF slag can be utilized as construction material in eco- friendly manner.