Coal boiler (ash types)

[novembertango88]

Hello all,
I'm trying to find a source of fly ash for use as a cement replacement in concrete. I have been contacting anyone I can find who is using a coal boiler.
One of these is a brewery which produces 15t of ash per day however, they have told me that they only have one source of ash and it sounds like bottom ash.
Is this how some boilers work or should I investigate further?
Thanks

 

[davefitz]

In most developed countries the coal fired boilers have bottom ash (clinkers 15%), economizer hopper ash(coarse 5%), and ESP ash (fine 80%). The largest amount of ash is the fine ESP ash. In undeveloped countries there may be no ESP so no ESP ash.

There is a new type of concrete that uses zero portland cement and uses 100% boiler flyash plus sodium hydroxide and sodium silicate, and it is called geopolymer cement ( and a similar variant called alkali activated cement). It has only 10% of the CO2 footprint of portland cement and has some other significant advantages, including it is fireproof to 2500 F and has 2500 times less porosity, so it prevents corrosion from seawater . See the info at <

http://www.geopolymner.org>

"...when logic, and proportion, have fallen, sloppy dead..." Grace Slick

 

[davefitz]

missspelled the link , it should be <

http://www.geopolymer.org>

also, in order to use flyash as an additive, there must be less than 5% by weight unburned carbon in the ash.

"...when logic, and proportion, have fallen, sloppy dead..." Grace Slick