PFA & Bottom ash from InterGens 850MW Millmerrin power station in South West Queensland

Fly ash is the residue from the combustion of coal. In the past it was generally released into the atmosphere, out the smoke stack, but pollution control equipment mandated in recent decades now require that it be captured prior to release. It is generally stored on site at most US electric power generation facilities. 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 silica (silicon dioxide, SiO₂) (both amorphous and crystalline) and lime (calcium oxide, CaO). Crystalline silica and lime are the major components of exposure concern. Understanding these concerns will help communities make informed decisions concerning the production, transport, storage and use of this material in their environment.

In and of itself, fly ash is neither toxic or poisonous, nor is it considered hazardous EXCEPT when it becomes airborne. Released into the atmosphere, fly ash can be extremely dangerous to humans as well as all other animals.  

Bottom Ash is created when the heavy particles that are not air borne stick to the walls of the furnace and develop into a heavier waste that falls to the power station floor, this is called bottom ash. Bottom ash has a similar composition to Fly Ash but can develop into large course lumps. Bottom ash and boiler slag represent approximately 10% of the ash waste created in power stations.

Class F fly ash

The burning of harder, older anthracite and bituminous coal typically produces Class F fly ash. This fly ash is pozzolanic in nature, and contains less than 10% lime (CaO). Possessing pozzolanic properties, the glassy silica and alumina of Class F fly ash requires a cementing agent, such as Portland cement, quicklime, or hydrated lime, with the presence of water in order to react and produce cementitious compounds.

Class C fly ash

Fly ash produced from the burning of younger lignite or subbituminous coal, in addition to having pozzolanic properties, also has some self-cementing properties. In the presence of water, Class C fly ash will harden and gain strength over time. Class C fly ash generally contains more than 20% lime (CaO). Unlike Class F, self-cementing Class C fly ash does not require an activator. Alkali and sulfate (SO₄) contents are generally higher in Class C fly ashes. (Wikipedia)

The 174 Quad Ultra Vac has the huge vacuum and air flow required to lift Fly Ash, PFA and Bottom Ash.

Coal Fly Ash, Bottom Ash and PF ash can be fist sized lumps of burnt coal. Very abrasive, heavy and sometimes very fine. This type of waste will destroy electric vacuums very quickly getting into the motors and burning out the brushes, wearing down the motor parts and sometimes just ceasing the engines. Very nasty stuff. To be effective in the recovery of fly ash and pfa a system with no moving parts and air powered is what is required. Vacteck's 174 Quad is just the system for this kind of rugged treatment.  With no moving parts, air powered, 4 independant air vacuum generators, huge suction power, awesome air flow (over 2200 CFM of free air delivery) this system is the big daddy of the drum vac market. With drum crushing power the 174 Quad keeps going and going when all the others run away and hide.