Single Step Extractions of Metals in Coal Fly Ash

Abstract

There is an increasing use of coal and subsequently large amounts of fly ash is generated in the thermal power plants in India and elsewhere in the world. Hence it becomes increasingly important to be able to assess the environmental risks involved in the management and disposal of fly ash materials. The fly ashes contain toxic metals that can be released into the environment through the coal combustion processes and through the leaching during disposal/ wet storage/ reuse of fly ash. The evaluation of the optimum time for leaching of the toxic metals and metalloids present in the three fly ashes was determined using the single step extraction procedure. The optimum time of 4 hours agitation was determined for the water soluble step as well as that for ion exchangeable step while the optimum time was 24 hours agitation in the acid soluble and reducible steps.