The majority of steaming coal used to fuel our power stations in Britain is mostly imported from South Africa by ship. It arrives at the power station as small pieces of between 25 and 50mm, and is stored in the stockpile in large mounds. From here it is conveyed to the coal pulverisers and into the boiler furnace. Steam is raised to power a turbine driving an electric generator. A fume treatment plant removes particles of dust and ash by precipitation and sulphur dioxide through a desulphurisation plant. The furnace and processed ash is sold as aggregate and gypsum, the by product from lime scrubbing is sold to the cement, plasterboard and fertiliser industries. Wastewater is treated with chemicals and filtered before being discharged.