Standard Of The Month

IS 10153:2021 Utilization of Fly Ash- Guidelines

At present there are hundreds of thermal power plants in the country producing over 200 million tonnes of fly ash per annum. Fly ash is a finely divided residue resulting from the combustion of ground or powdered coal/combustible waste and transported by the flue gases of boilers fired by pulverized coal.

The ash content of most of the coal used in these plants is above 35 percent. Since, low ash, high grade, coal is reserved for metallurgical industries, railways, etc., the thermal power plants have to utilize high ash, low grade, coal and by-product fuel from coal washeries. It has been estimated that the average ash content of coal which will be available for thermal power plants in the coming years will further increase.

The use of fly ash as a pozzolana, a fine aggregate and for other allied purposes is well established in India. Investigations have proved the suitability of fly ash for various uses. Indigenous fly ashes for partial replacement of cement, as an admixture for concrete and as a fine aggregate for mortar and concrete have already been successfully tried out and greater attention is now being paid to fully exploit the potentialities of fly ash as construction material.

Disposal of fly ash is a problem being faced by most of the thermal power plants where it is being produced. This material, however, may be utilized in a number of ways, some of which have been mentioned above. If proper means and methods are not adopted for utilization of fly ash the problem will increase in magnitude, due to its increased production, over the next few years.

This standard lays down guidelines for utilization of fly ash. Fly ash may be collected from the flue gases, in thermal power plants, by mechanical collectors or electrostatic precipitators or a combination of both. It may be removed by “wet system’ or ‘dry system’. The ‘wet system’ involves mixing the fly ash with water and sluicing it to a settling tank or dumping areas. The ‘dry system’ involves removal of the fly ash in dry form either directly by screw feeders discharging into transport vehicles from the hoppers or by means of pneumatic conveying system for further utilization or storage The standard was initially published in 1982. Over the course of time, uses and disposal methods of fly ash has changed significantly. In 2021 version, the recent developments with regard to standardized uses and their techniques have been explored and guidelines have been provided.