The invention belongs to the technical field of
phosphorus chemical industry production, and particularly relates to a method for producing
phosphoric acid and co-produced
gypsum powder by a
hemihydrate process. The method for producing the
phosphoric acid and co-produced
gypsum powder by the
hemihydrate process, provided by the invention, is used for solving the problem that co-produced
gypsum of the existing
hemihydrate processes cannot reach standards of building gypsum. The method provided by the invention comprises the following steps: returning
slurry of a crystallizing tank to a pre-reaction tank, and enabling the
slurry to make a pre-reaction with
phosphorite; in a reaction tank, enabling SO4<2-> remaining in the returned
slurry to make a further full reaction with CaO in the
phosphorite; adding H2SO4 into the crystallizing tank so as to obtain semi-hydrated gypsum, and carrying out filtrating, washing and free-water removal, thereby obtaining the gypsum
powder, of which the length-
diameter ratio is (2 to 10): 1. The
setting time,
breaking strength and compression strength of the gypsum powder prepared by adopting the process are superior to those required in the standards of the building gypsum. The method has the advantages that the
energy consumption is lowered, process flows are shortened, the difficulty of subsequent treatment of gypsum produced during the preparation of
phosphoric acid by the hemihydrate process is lowered, the range of utilization of ardealite is widened, and the
pile-up pressure of gypsum storage yards is lightened.