Pulverised Fuel Ash, PFA, (“fly ash” – it is dusty!) is created when a coal fired power station burns coal.

The Welsh coal used to Aberthaw was particularly hard, burning at a very high temperature (around 1800 degrees). Before entering the furnace, the coal was crushed to increase the surface area. During combustion, most of the carbon oxided, but not all. During the heating process the embedded alumina silicate (sort of “glass” / “sand”) melts and detaches itself from the remaining carbon particles. As it cools, the silicate formed tiny spheres.

What remained was unburnt coal (carbon – around 10-20%) and alumina silicate stored in a stock-pile, like other power stations around the world. There are 17 million tonnes of stock-piled ash at Aberthaw.

The Celtic Minerals method seperates the carbon from the alumina silicate to allow each component to create a useful product. There is also an opportunity to harvest a third product, cenospheres (tiny silicate spheres with an embedded air bubble) during the seperation process.