INTEGRATED METHOD FOR PRODUCING A BUILDING MATERIAL FROM PHOSPHOGYPSUM

The invention relates to a method for producing sulphuric acid and cement clinker using calcium sulphate, which is formed and separated as a solid by-product during the production of phosphoric acid when raw phosphate is reacted with sulphuric acid to form phosphoric acid, wherein the method comprises the following steps: a) the calcium sulphate separated from the phosphoric acid is treated with an acid in order to obtain a suspension containing purified calcium sulphate; b) the purified calcium sulphate is separated from the liquid phase of the resulting suspension as a solid material, wherein the obtained liquid phase can be introduced into the reaction unit of the phosphoric acid production as a feedstock; c) the separated purified calcium sulphate is mixed with additives and reducing agents in order to obtain a raw meal mixture for cement clinker production, wherein, in the raw meal mixture, the calcium component for the cement clinker is formed preferably entirely from the separated purified calcium sulphate; d) the raw meal mixture is burnt in order to obtain the cement clinker, and sulphur dioxide is formed as a waste gas; and e) the resulting sulphur dioxide is supplied to a sulphuric acid production as a raw material in order to produce the sulphuric acid, wherein the produced sulphuric acid is used as a feed material in phosphoric acid production. The method is, in particular, an integrated method. The integrative approach as an overall concept ranging from phosphogypsum to cement clinker and sulphur dioxide takes into consideration the requirements in an existing phosphoric acid and sulphuric acid complex, as well as the requirements of producing high-quality products from phosphogypsum.