FIELD: chemical industry.
SUBSTANCE: method of the production of sulfuric acid and cement clinker and the production of rare earth elements using calcium sulfate formed and separated as a solid by-product in the production of phosphoric acid by reacting phosphate raw materials with sulfuric acid to form phosphoric acid is proposed. The calcium sulfate separated from the phosphoric acid is treated with an inorganic acid to obtain a slurry containing purified calcium sulfate. Then the purified calcium sulfate in solid form is separated from the liquid phase of the resulting suspension and treated with water or an aqueous solution containing a salt and/or a chelate ligand to leach rare earth elements (REE) from calcium sulfate. The additionally purified calcium sulfate is separated in solid form from the liquid phase of the slurry with one or more REE present in the liquid phase. Purified calcium sulfate is mixed with additives, which are raw materials or compounds, including one or more oxides selected from oxides of Si, Al, Fe, and optionally Ca, or their precursors, and reducing agents, which are carbon and/or hydrocarbons, and/or elemental sulfur to obtain raw meal for the production of cement clinker. The raw meal is calcined to produce cement clinker, producing sulfur dioxide as an off-gas, which is fed as a raw material to the sulfuric acid plant to produce sulfuric acid.
EFFECT: invention makes it possible to reduce the impact of deposits and/or burials of phosphogypsum on the environment, providing its complex processing and extraction of REE with high yield and purity.
12 cl, 3 dwg, 12 ex
