Cement, Energy & Environment

/ . cement manufacturing processes account for majority of the fly ash demand. The company has entered into long-term contracts with various cement manufacturers in this regard. Besides cement, other key demand segments for fly ash utilization at Mahagenco's plants include agriculture, asbestos, land-fills and bricks. There is also a provision for reserving 20 per cent of fly ash for small-scale industries. Typically, fly ash is lifted by the cement manufacturing units and brick kilns located in the vicinity of projects, while the remaining is dumped in ash ponds. Among the recent initiatives, abandoned ash pond sites are being reclaimed and afforestation is being carried out at these sites. Mahagenco has provided railway tracks to the silos that store fly ash and is exploring possibilities of using railway wagons for ash transportation to the cement industry. A feasibility study for rail linkages for ash disposal is being carried out for the company's Parli thermal power station. Railway transportation is being actively considered by the company to circumvent issues of pollution through road transportation . Long-term ash utilization contracts have been signed with cement manufacturers. These contracts are based on the build-own-operate or build-own-transfer models and have a term of 15-30 years. The company has also utilized the results from studies and research projects, which highlight the applications of fly ash in agriculture. Select experiments and demonstrations have been taken up at power stations in Nasik, Parli and Chandrapur. At the Parli station, land for an ash pond was reclaimed for tree plantation. The state government has also provided support for promoting this mode of ash utilization. DVC The Damodar Valley Corporation (DVC) has undertaken ash utilization mainly through mine filling. This involves disposing fly ash in abandoned open cast mines with a provision of earth cover on the top for facilitating plantation. The company has been carrying out ash-based mine filling since 1996-97, much before the issue of government guidelines on ash utilization. Stricter enforcement by the pollution control boards. along with ash utilization conditions for upcoming plants. is contributing towards better adherence to ash disposal norms Notably, mine filling was not considered as a potential area of fly ash utilization then. DVC's steps towards open cast mine filling are supported by the fact that most of the company's power stations are located near coal mines. It thus became convenient to exploit the abandoned mines for dumping ash from coal-fired plants. Among other areas, DVC is also increasing the utilization of dry fly ash for the manufacturing of cement, bricks, blocks, etc. The maximum quantity of fly ash and bottom ash is taken to ash lagoons in slurry form. Ash slurry is pumped into the ash ponds through a set of pipelines. These ponds are constructed in a way that allows ash particles to settle, while the decanted water flows into the rivers. At DVC's new plants, decanted water is being recycled and used for slurry. Following the settling down of ash, the same is dumped in an abandoned open cast pit. Ash is collected in ash ponds alternatively so that the evacuation programme can be taken up smoothly. Ash evacuation from the ponds involves the use of equipment such as excavators, payloaders, bulldozers, etc., while leak-proof dumpers are deployed for transporting ash to open cast mines. Loaded dumpers are often sprayed with water to check for possible spillage of ash during transportation . The same process is undertaken during the dumping of ash at the mines. DVC is considering other avenues for ash utilization. These include agricultural consumption, wasteland development and low– cost binding material for use in construction, especially in rural areas. Also, there are concerns about environmental impact including air pollution and ash effluents flowing into water bodies. Courtesy: Power Line, Dec. 2012, Pp27-28. WASTE VALUE- CONCERNS ABOUT VIABILITY The waste-to-energy (WtE) segment in India has significant but unrealized potential. In line with previous years' trends, the segment witnessed modest growth over the past year as well. Only three urban WtE projects with an aggregate capacity of 30MW were commissioned in the past 12 months, taking the total installed WtE capacity to a mere 200 MW. However, WtE has been catching on as a means to achieve both waste and energy management goals. The municipal corporations of Kochi, Chennai, Surat and other 33