Impact On Leaching Behaviour Of Toxic Metals In Ferrochrome Ash With Varying Ph Levels

Abstract

In the current investigation, leaching behaviour of cobalt (Co), copper (Cu), iron (Fe), zinc (Zn), calcium (Ca), arsenic (As), cadmium (Cd), chromium (Cr), mercury (Hg), nickel (Ni), lead (Pb) and selenium (Se) from fresh and aged Ferrochrome Ash (FCA) samples were studied under various pH conditions (3-11). Results reveal that most of the elements follow oxyanionic leaching pattern where increase in pH increases the effluent concentration of elements. Leached As, Pb, Hg, Ni and Fe reached peak concentration at alkaline phases. Cd, Cr and Zn followed cationic leaching pattern where increase in pH decreases the concentration. Any specified pattern of leaching is not followed by Ca, Se, Co and Cu. Results of leaching test reveal that the high concentration of chromium leaching was found to be 156.18 and 155 mg/L, concentration of arsenic 13.46 and 12.89 mg/L, concentration of mercury 10.23 and 10.4 mg/L and lead concentration of 6.58 and 6.72 mg/L for fresh and aged FCA ashes respectively. Hence Cr, As, Hg and Pb are identified as significant hazardous pollutants and must not be discharged without being solidified/stabilized. Leached element concentration was not affected significantly by aging of the FCA.