Abstract: The invention relates to a method for manufacturing ammonium sulphate and calcium carbonate from phosphogypsum, characterised in that it comprises the following steps: —dispersing phosphogypsum in water to form a phosphogypsum liquid suspension, —sparging gaseous carbon dioxide and gaseous ammonia in the phosphogypsum liquid suspension to precipitate calcium carbonate, —filtering the phosphogypsum liquid suspension to produce a filtrate comprising ammonium sulphate, and a solid residue comprising the calcium carbonate precipitate, —evaporating the filtrate to produce ammonium sulphate and drying the solid residue to produce calcium carbonate.

Abstract: The present invention relates to a process for purifying and concentrating rare earths contained in phosphogypsum, characterised in that it comprises the following steps of: from a phosphogypsum, a) Leaching the phosphogypsum with a solution of one or more strong acid(s) selected from among: sulphuric acid, nitric acid and hydrochloric acid, in order to obtain a leaching mixture comprising a liquid phase formed by a leaching solution containing rare earths from the phosphogypsum and the leaching acid, and a solid phase comprising the phosphogypsum, b) Adding, to the phosphogypsum, an oxidising agent to promote passage of the rare earths from the phosphogypsum into the leaching solution, and/or a reducing agent to reduce solubility of mineral impurities contained in the leaching solution in order to allow their passage from the leaching solution into the solid phase, c) Separating the liquid phase enriched in rare earths and depleted in mineral impurities, and the solid phase enriched in mineral impurities.

Abstract: A method for manufacturing a ceramic material for thermal energy storage, includes producing a mixture of at least particles of clay and particles of natural and/or synthetic phosphate, and water, the mixture comprising between 0.5% and 40% by weight of phosphate compared to the weight of the mixture with the exception of water, and shaping and firing of the mixture to obtain the ceramic material. A ceramic material for thermal energy storage includes: a matrix of clay and, if appropriate, sand, and particles of a natural and/or synthetic phosphate dispersed in the matrix, the ceramic material comprising between 0.5% and 40% by weight of phosphate compared to the weight of the ceramic material.