Metallgesellschaft Aktiengesellschaft

Metaligesellschaft Aktiengesellschaft

Dieter Grone

Harald Sauer

Wenzel Von Jordan

Rolf Draf

The process for purifying gypsum suspensions, particularly those formed in a flue gas desulfurizing plant, includes feeding the gypsum suspension (9) to a first hydrocyclone (1), which is operated to produce an underflow (11) with a comparatively high underflow concentration and an overflow fed to a collecting tank (2). The underflow (11) of the first hydrocyclone stage is further diluted to a form another underflow with a lower solids content in a suspension tank (3) and then is fed to a second hydrocyclone stage (4), the overflow of which is also fed to the collecting tank (2). Depending on purity of the gypsum required or attained, the gypsum contained in an underflow (14) of the second hydrocyclone stage (4) is either immediately dewatered and removed or is first fed to one or more hydrocyclone stages, which operate analogously. The combined overflows (15) of the first and second or further hydrocyclone stages are fed from the collecting tank (2) to a third hydrocyclone stage (6). In a thickener (8) solid particles are removed from the overflow (17) of the third hydrocyclone (6) and the clear effluent (23), which is an overflow from the thickener (8), is used for diluting in the suspension tank (3).

Process of purifying gypsum

The dry slaking of lime is carried out continuously in a vessel from which an exhaust gas is removed. Hot gas, preferably a flue gas to be desulfurized, is added to the exhaust gas to prevent it from contacting the inner surface of the exhaust gas duct and thereby reduce the tendency for deposits in lines traversed by the exhaust gas.

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Frankfurt am Main, Germany

Dieter Grone