Cement Manufacturers Association (CMA)

61 Higher grades of coal are reserved for metallurgical applications. When pulverized coal is burned in a furnace at the power stations, it produces very fine ash called “Fly ash” which comes out of the furnace along with flue gases. Fly ash accounts for about 75-85 per cent of the total ash formed. The remaining coarser fraction of the ash falls to the bottom of the furnace where it sinters to form “Bottom ash”. Fly ash is removed from the flue gases using electrostatic precipitators (ESP) and is initially collected in ESP hoppers. This ESP dry fly ash is conveyed to the silos pneumatically from where it is generally taken by the user agencies. Bottom ash (after crushing by jaw crusher) and available fly ash from hopper/ silos are mixed with water and disposed-off in a slurry form to ponds. This deposit is called “Pond ash”. However, generally the term fly ash is used as a generic name to denote any of these three types of ashes. Fly ash availability is widely spread across the country. Properties of Fly Ash The physical and chemical properties of fly ashes vary, within acceptable range, depending upon the type of coal, its grinding and combustion techniques, and their collection and disposal systems. Fly ash (especially when collected from ESP in dry form) reacts with lime in presence of moisture to form cementitious compounds. This is known as pozzolanic activity. The pozzolanic property of fly ash enables it to be used in concrete to replace a part of cement. Current Scenario The prevalent practice is to dump fly ash and pond ash on wastelands, and this has lain to waste thousands of hectares all over the country. These sites are not lined and it leads to seepage, contaminating groundwater and soil. It lowers soil fertility and contaminates surface and ground water as it can leach into the subsoil. When fly ash gets into the natural draining system, it results in siltation and clogs the system. It also reduces the pH balance and portability of water. Installed power station capacity in India as on March 31, 2026 (in MW) Hydroelectric power plants with < 25 MW generation capacity are included in Renewable category (classified as SHP - Small Hydro Project) Sector Fossil (Thermal Power) Non - fossil (Clean Power) Total(MW) Coal Lignite Gas Diesel Total fossil Nuclear Largehydro Renewable Total non- fossil Central 73230 3640 7237.91 - 84107.91 8780 18038.72 13181.29 40000.01 124107.92 State 75647.50 1150 6961 280.31 84038.82 - 27524.94 18436.23 45961.17 129999.99 Private 73062.51 1830 5923.50 308.89 81124.90 - 5851 191655.91 197506.91 278631.81 All Indla 221940.01 6620 20122.41 589.20 249271.63 8780 51414.66 223273.43 283468.09 532739.72 Percentage 41.66 1.24 3.78 0.11 46.79 % 1.65 9.65 41.91 53.21 % 100