The calcium sulphite, which is primarily generated in the absorber stage of the flue gas desulphurisation (FGD), is oxidized with oxygen from the flue gas and air is additionally injected into the calcium sulphate dihydrate (gypsum).
Depending on the plant design, the suspension containing more or less calcium chloride is firstly thickened via a separation plant – (hydrocyclones). Afterwards, the gypsum is dewatered in the downstream vacuum belt filter installation. If required, the remaining chloride can be washed out of the gypsum, which can be used as a valuable by-product for the building materials industry.
For the flue gas desulphurisation – gypsum dewatering, ENGINEERING DOBERSEK GmbH supplies vacuum band filters for dewatering. The gypsum suspension is dewatered by means of a hydrocyclone band filter separation stage and - if required - washed, then via belt conveyors transported to a gypsum silo or a gypsum deposit. Continuously working vacuum belt filters prossess a high availability and reliability. Besides this the vacuum belt filters provide a residual moisture from the FGD-gypsum of less than 10 % without any difficulty.