The resemblance in the trend of heavy metal concentration
among the various thermal processes waste is clearly indicated in
Fig. 2d. A similar trend was observed between the waste of thermal
processes such as ZnM & PbM and Fecas and NFecas. Most of
the manufacturing processes involved in ZnM and PbM are similar
such as updrought/downdrought sintering, Imperial Smelting
Furnace and Waelz kilns fuming furnaces [34] and thus the distributions
of the heavy metals in waste may be similar (Fig. 2d). Being
the metal casting industries, Fecas and NFecas both involves melting
and refining as major processes [33] and thus they resembles
the same type of waste characteristics (Fig. 2d).