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Author Topic: Is coal fly ash a synthetic compound?  (Read 546 times)

Offline tkadm30

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Is coal fly ash a synthetic compound?
« on: 08/08/2016 12:19:25 »
Does fabrication and processing of coal fly ash using a combustion process is different than volcano ash?


 

Offline evan_au

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Re: Is coal fly ash a synthetic compound?
« Reply #1 on: 08/08/2016 12:44:16 »
Yes, they are quite different substances. But they are both bad for you if you breathe them in high concentrations (or in low concentrations for a long time).
- Volcanic ash consists primarily of silicates, with a similar chemical composition to lava. The force of the volcanic explosion blasts it into fine particles.
- Coal fly ash consists of all the non-flammable minerals in the coal. This can consist of some dirt (silicates) that was scooped up with the coal, but there are a variety of minerals that the plants use, which are incorporated into the coal.
- The gases that are released are important for lung function. As well as water and carbon dioxide, there are oxides of sulphur, nitrogen and other irritating gases.

The main difference is that fly ash is removed from the exhaust gas of the power station (in most jurisdictions). But nobody has worked out how to capture the ash from an explosive volcanic eruption, and thick plumes can reach the cruising altitude of jet planes.
See: https://en.wikipedia.org/wiki/Volcanic_ash#Chemical
https://en.wikipedia.org/wiki/Fly_ash#Chemical_composition_and_classification

In one case, a jet had a simultaneous failure of 4 engines, but they were able to restart the engines after they "glided" below the altitude of the ash cloud.
https://en.wikipedia.org/wiki/British_Airways_Flight_9
 
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Offline evan_au

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Re: Is coal fly ash a synthetic compound?
« Reply #2 on: 08/08/2016 12:51:46 »
Quote from: tkadm30
Is coal fly ash a synthetic compound?
If it comes from a natural source (eg when lightning ignites a coal seam), it would have to be considered natural, rather than synthetic.
 

Offline tkadm30

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Re: Is coal fly ash a synthetic compound?
« Reply #3 on: 08/08/2016 13:07:05 »
Quote from: tkadm30
Is coal fly ash a synthetic compound?
If it comes from a natural source (eg when lightning ignites a coal seam), it would have to be considered natural, rather than synthetic.

Is it possible to synthetically modify coal fly ash as part of the combustion process?

I suppose the mecanical processing of coal fly ash may be engineered when producing a aerosol agent to optimize its particle size?
 

Offline chiralSPO

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Re: Is coal fly ash a synthetic compound?
« Reply #4 on: 08/08/2016 14:45:42 »
If this conversation goes at all closer to coal fly ash being sprayed out of planes, I'm moving this thread out of chemistry! As long as it remains a discussion of the composition and properties of coal fly ash, it can stay.

Is it possible to synthetically modify coal fly ash as part of the combustion process?

I suppose the mecanical processing of coal fly ash may be engineered when producing a aerosol agent to optimize its particle size?

Coal fly ash is a product of the combustion process, so there is potentially some control over the properties of the ash based on how the combustion is performed. However, engineers optimize the combustion process to provide maximum energy for their power plants, and the ash is just a pesky side product. I don't think there is much work done on changing the properties of coal ash, other than perhaps trying to make it easier (cheaper) to capture and contain.
 

Offline Bored chemist

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Re: Is coal fly ash a synthetic compound?
« Reply #5 on: 08/08/2016 20:21:59 »
"Is coal fly ash a synthetic compound?"
No it's a mixture of compounds.

"Does fabrication and processing of coal fly ash using a combustion process is different than volcano ash?"
Since neither product has a fixed or even very well defined composition, it's not easy to say.
 

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Re: Is coal fly ash a synthetic compound?
« Reply #5 on: 08/08/2016 20:21:59 »

 

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