Research Scholar (PhD), IIT Bombay
Making an economic, environment friendly, and effective construction material from industrial waste
Since coal is one of the major source of power worldwide, the problem of post coal combustion products, will be prominent. In coal with high ash content, as is the case in India and many other countries, problem of fly ash mitigation is a challenge for the coal power sector. Though fly ash is a highly desirable product by cement industry due to its ostentatious nature in presence of external source of lime, the fact remains that huge amounts of fly ash is not utilized and simply dumped in open fields. These open dumps become heavy pollution trigger points, causing particulate air pollution, local body water pollution, and huge land wastage. One of the major challenges is its transportation cost, i.e. taking ash from its source (coal fired power plants) to place of application or use becomes very uneconomic. Another major challenge for the power industry is the ash generation quantity considering the high ash contents of Indian coals. The ash generation is way too high compared its utilization in the cement industry. Apart from these, another important hindrance in optimum utilization of fly ash is lack of sufficient and significant research. All these factors have to be tackled in order to make a zero-waste power sector. The main aim of this research is to examine and establish the use of fly ash as a construction material for haul roads in opencast coal mines. Haul roads, being lifelines of mines, need to be in good working condition in order to support unhindered movement of mine haulage and to maintain uninterrupted production. Traditionally, the construction material used in haul roads is just rolled and crushed mine waste (overburden) in a belief that it favours mine economics and the option of cementing or using any other binder for construction will make it uneconomic in mine setting. This practice results in various structural instabilities in haul roads resulting in various breakdown times and consequently increase the maintenance cost of both haul road and the dumpers running on them. Using fly ash as construction material will not only increase the stability of haul road but will be economical and environment beneficial.
Abstract: This work supports, for the first time, the integrated management of waste materials arising from industrial processes (fly ash from municipal solid waste incineration and coal fly ash), agriculture (rice husk ash), and domestic activities (ash from wood biomass burning in domestic stoves). The main novelty of the paper is the reuse of wood pellet ash, an underestimated environmental problem, by the application of a new technology (COSMOS-RICE) that already involves the reuse of fly ashes from industrial and agricultural origins. The reaction mechanism involves carbonation: this occurs at room temperature and promotes permanent carbon dioxide sequestration. The obtained samples were characterized using XRD and TGA (coupled with mass spectroscopy). This allowed quantification of the mass loss attributed to different calcium carbonate phases. In particular, samples stabilized using wood pellet ash show a weight loss, attributed to the decomposition of carbonates greater than 20%. In view of these results, it is possible to conclude that there are several environmental benefits from wood pellet ash reuse in this way. In particular, using this technology, it is shown that for wood pellet biomass the carbon dioxide conversion can be considered negative.
Pub.: 10 May '17, Pinned: 29 Jul '17
Abstract: The purpose of this paper is to discuss the alternative environmental management options for the utilisation of municipal solid waste (MSW) incineration fly ash (FA), which is generated at Iru Power Plant where MSW is incinerated in Estonia. To determine sustainable and economically feasible environmental management options for MSW incineration FA in Estonia, CO2 sequestration with a further carbonation process was examined. A partial Cost & Benefit Analysis has been conducted to compare the carbonation process to the current situation. Two carbonation options were developed. Option 1 is to use carbonated FA in any other processes based on the waste-to-product principle. Option 2 is to send carbonated FA to the non-hazardous landfill in Tallinn, Estonia. Important parameters, such as Net Present Value (NPV), Internal Rate of Return (IRR), Benefit-Cost Ratio (BCR) and Break Even Point (BEP), have been calculated for carbonation options and the current case. In addition, a sensitivity analysis has been conducted to examine its robustness. The results showed that the best option is carbonation Option 1 with NPV of 9,209,662 EUR, IRR of 43%, BCR of 2.63 and BEP between 2018 and 2019. Both Options 1 and 2 constitute more sustainable and environmentally friendly management options compared to the current situation. It can be concluded that this preliminary feasibility study showed that running a carbonation plant may be profitable and sustainable for Estonia. Currently, there is no treatment technology for MSW incineration FA in Estonia and FA is sent to a neighbouring country for further utilisation. This is the first study to demonstrate FA management options with economic and environmental benefits.
Pub.: 26 May '17, Pinned: 29 Jul '17
Abstract: The properties of sub-base filling materials in highway construction are essential, as they can determine the performance of the road in service. Normally, the existing materials are removed and replaced with new materials that have adequate load-bearing capacity. Rising environmental concern and new environmental legislations have made construction professionals consider other methods. These methods include stabilizing the existing materials with other additives to improve their performance. Additives can be waste materials generated by different industries. In this work, the existing excavated soil is stabilized with waste materials. The wastes consisted of fly ash, marble dust and waste sand. The percentage addition of waste materials was 5%, 10%, 15% and 20% (by mass) of the existing soil. The soil/waste specimens were cured for 1, 7, 28, 56, 90 and 112 days before testing. Testing included the dry unit weight and unconfined compressive strength ( qu) as well as X-ray diffraction analysis and scanning electron microscopy observation. Also, the California Bearing Ratio values were obtained and are reported in this investigation. The results showed that the qu values increased with the increase in waste materials content. Also, there is tendency for the dry unit weight to increase with the increase in waste materials.
Pub.: 14 Jun '17, Pinned: 29 Jul '17
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