Analysis of Leachate Characteristics to Study Coal Ash Usability - Management of Natural Resources in a Changing Environment - page 234

particles are sized in between fl y and bottom ashes (Pandian et al. 1998 ). The SEM
microphotograph shows the presence of solid spherical cenospheres in the samples
and also reveals that it is a mixture of spherical particles of different sizes between
fl y ash and bottom ash. The Loss on Ignition is an indirect parameter to indicate the
presence of unburnt carbon. Fly ash also contains a variable amount of unburned
carbon, depending on the combustion conditions (Palo 2006 ). The result indicates
that LOI is in the range of 0.03-0.12 % (Table 2 ), which is very less and indicate the
high temperature combustion (Palo 2006 ).

pH of Coal Ash

pH of the coal ash samples were analysed and results are shown in Table 3 . Result
of pH varied from 7 to 8.1 and indicates that coal ash samples are slightly alkaline.

Leachate Analysis

The leaching test such as the batch test may provide a reasonable approximation of
environmental leaching behaviour of CCPs. After batch leaching test the leachate of
coal ash samples were collected and analysed.

pH of Leachate

Table 3 shows the pH values of leachate from coal ash samples after batch leaching
test. The pH of leachate was found to be in the range of 6.2-6.5. The pH was found
to be less when compared to the pH of the initial coal ash samples. This could be
attributed to the consumption of hydroxyl ion by precipitation of secondary minerals
over time (Izquierdo 2012 ).

Trace Elements Analysis

The mode of occurrence of trace elements in coal plays a primary role in the distri-
bution of elements within ash particles. The elements enriched in the core of fl y ash
particles are not directly exposed to leaching, whilst surface associated elements are

Table 3 pH of coal ash
samples and its leachate

Sample No. pH of sample pH of leachate

1 7.0 6.24

2 7.5 6.22

3 7.6 6.46

4 8.1 6.64

5 7.6 6.50