Investigation of characteristics and leaching behavior of coal fly ash, coal fly ash bricks and clay bricks

•Four laboratory leaching test (TCLP, SPLP, CAL-WET and DWLP) were investigated.•Detail characteristics of collected samples were also evaluated.•Leaching tests shows concentrations of 12 heavy metals in collected samples.•Study encourages used of fly ash bricks compared to clay bricks.

The leaching potential of heavy metals from Coal Fly Ash (CFA), Coal Fly Ash Bricks (CFAB) and Clay Brick (CB) were assessed through four laboratory batch leaching procedures. The concentration of 12 heavy metals were analyzed to study heavy metal leaching from CFA, CFAB and CB in surrounding environment. The heavy metal concentrations of CFA, CFAB and CB through various leaching studies conducted were compared with those estimated through acid extraction/digestion including physico-chemical, mineralogical and morphological characterization. The comparative assessment between CFAB and CB were also undertaken to study the leaching of heavy metals vis-a-via laboratory batch leaching procedures. The major compounds present in collected samples were SiO2, Al2O3 and Fe2O3 while minor compounds include such as K2O, TiO2, CaO, MgO, P2O5 and SO3. The most abundant heavy metals leached out during laboratory batch leaching studies were Al>Fe>Mn>Zn followed by other heavy metals. The study also emphasized the use of CFAB compared to CB in and around thermal power stations due to environmental suitability in the terms of leaching behavior.

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