Alternative Energy

[MSC290]

Fly Ash Information

Fly ash is one of the residues generated in the combustion of coal. Fly ash is generally captured from the chimneys of coal-fired power plants, whereas bottom ash is removed from the bottom of the furnace. In the past, fly ash was generally released into the atmosphere, but pollution control equipment mandated in recent decades now require that it be captured prior to release. In the US, it is generally stored at the power plant. Depending upon the source and makeup of the coal being burned, the components of the fly ash produced vary considerably, but all fly ash includes substantial amounts of silicon dioxide (SiO2) (both amorphous and crystalline) and calcium oxide (CaO). Fly ash is commonly used to supplement Portland cement in concrete production, where it can bring both technological and economic benefits, and is increasingly finding use in the synthesis of geopolymers and zeolites.

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http://en.wikipedia.org/wiki/Fly_ash

Another article from today about fly ash:

Cenocell Will Turn Coal Ash Into Cement Without Concrete

By News Staff - November 28th 2008 - Scientific Blogging

Each year, coal-burning power plants, steel factories and similar facilities in the United States produce more than 125 million tons of waste, much of it fly ash and bottom ash left over from combustion. Mulalo Doyoyo has plans for that material.

An assistant professor in Georgia Tech’s School of Civil and Environmental Engineering, Doyoyo has developed a new structural material based on these leftovers from coal burning. Known as Cenocell™, the material offers attributes that include high strength and light weight – without the use of cement, an essential ingredient of conventional concrete.

With broad potential applications and advantages such as good insulating properties and fire resistance, the “green” material could replace concrete, wood and other materials in a broad range of applications in construction, transportation and even aerospace.

“Dealing with the ash left over from burning coal is a problem all over the world,” said Doyoyo. “By using it for real applications, our process can make the ash a useful commodity instead of a waste product. It could also create new industry and new jobs in parts of the world that need them badly.”

Fly ash is composed of small particles removed from combustion gases by pollution control systems. Most of it must now be disposed of as a waste product, though certain types of fly ash can be used to replace a portion of the cement used in conventional concrete.

Cenocell, produced from either fly ash or bottom ash in a reaction with organic chemicals, requires none of the cement or aggregate – sand and rock – used in concrete. And unlike concrete, it emerges from curing ovens in final form and does not require a lengthy period to reach full strength.

“This is a new material very different from concrete,” Doyoyo said.

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http://www.scientificblogging.com/news_releases/cenocell_will_turn_coal_ash_cement_without_concrete