Question

Ash is produced by:
A. Petroleum
B. Natural gas
C. Coal
D. All of the above

Answer 1

Hint: Fly ash basically consists of inorganic matter within coal that has been melted at high temperature. To solve this question, we need to know about different properties of fly ash and also how it is produced.

Complete step by step answer:
Fly ash is basically the finely divided residue that results from the combustion of pulverized coal and is transported from the combustion chamber by exhaust gases. It is produced by coal-fired and steam generating plants. The coal is pulverized and blown with air into the boiler’s combustion chamber where
it immediately ignites, generating heat and producing a molten mineral residue. The boiler tube extracts heat from the boiler thus cooling the flu gas and causing the molten mineral residue to harden and form ash. The coarse ash particles referred to as bottom ash or slag fall to the bottom of the combustion chamber while the lighter fine ash particles termed as fly ash, remain suspended in the flue gas.
Now, let’s discuss the shape and size of the fly ash. It consists of silt-sized particles which are generally spherical and typically range in size between 10-100micron. These gas spheres improve the fluidity and workability of fresh concrete. So, it is produced by coal.

Hence, option C is correct.

Note: Fly ash is most commonly used as a pozzolan in PCC applications. Moreover, Pozzolans are siliceous or luminous materials which react with calcium hydroxide at ordinary temperature to produce cementitious compounds. The chemical composition of fly ash relates directly to the mineral chemistry of the parent coal and any additional fuels or additives used in the combustion or post-combustion Processes.