104 results about "Pulverised fuel ash" patented technology

Pulverised fuel ash, is a waste product of pulverised fuel fired power stations. The fuel is pulverised into a fine powder, mixed with heated air and burned. Approximately 18% of the fuel forms fine glass spheres, the lighter of which are borne aloft by the combustion process. They are extracted from the flue gasses by cyclones and electrostatic precipitation. The resultant material is used as engineering fill and as a component for concrete. It has been widely used, particularly in the UK, for concrete block production. The blocks are lightweight and have excellent thermal insulation properties. PFA can undergo a pozzolanic reaction and become brittle over time. PFA has a fine dust texture and is grey in colour. When newly produced the dust is strongly alkaline; a pH as high as 11 is known, and >9 is normal. It leaches a solution dominated by sodium and sulfate, with enough boron to kill most plants, though coastal species often tolerate the salinity and boron to grow on young ash lagoons. In dry conditions these solutes rise to the surface to form a hard salt crust, impeding all plant growth, though hardy grass species such as Vulpia myuros can later colonise it.