Process for operating a gypsum/sulphuric acid plant

摘要

In this process, conversion of the gypsum serving as feedstock into anhydrite in a separate plant is omitted. Instead, the gypsum is first subjected only to partial dehydration down to a surface water content of 10-15% by weight. A two-step drying and calcining of the gypsum is then carried out in which the SO2-containing waste gas of the furnace is used as heat-transfer medium. At the same time, dust is removed from this waste gas to such an extent that it can be passed without any further gas treatment into the gas scrubber of the sulphuric acid plant. After passing the second drying step, the dried and calcined gypsum still has a total water content of about 6% by weight and is passed directly together with the addition materials via a conveying element into the heat-exchanger of the furnace, so that the furnace powder is mixed in the conveying element and/or heat-exchanger.