METHOD OF PROCESSING PHOSPHOGYPSUM WASTES TO OBTAIN A CONCENTRATE OF REE AND GYPSUM PLASTER Russian patent published in 2019 - IPC C22B59/00 C22B3/08 

FIELD: waste processing and disposal.

SUBSTANCE: invention relates to recycling production wastes and environmental protection and can be used in chemical industry and other industries associated with use of rare-earth elements, as well as the binder binding agent of construction gypsum released during production can be used in construction. Extraction of REM from phosphogypsum involves treatment of phosphogypsum with sulfuric acid solution in at least one step, filtration, extraction of insoluble REE precipitate from obtained solution by introduction of acetic acid or its soluble salts at consumption for deposition 35÷95 mol% on REE from a stoichiometrically required amount in a circulating solution in a deficiency while maintaining a pH of the mother solution of less than 3.0. Precipitation of the REE acetates is separated from the mother solution, washed, dried and optionally calcined to obtain a REE concentrate in a salt or oxide form. Separated mother solution containing sulfuric acid and REE in sulphate form is directed as a recycle stream into a unit for neutralization of phosphogypsum, where a balance amount of sulfuric acid is supplied to compensate its losses with salts of REE and gypsum pulp. Filtered phosphogypsum undergoes additional washing from residual amounts of sulphate REE with mother solution, from which precipitate of insoluble REE compounds is separated by way of acetic acid introduction and sediment separation by filtration. Washed phosphogypsum is neutralized with the main calcium compound CaO in order to neutralize trace amounts of sulfuric acid, dried and realized as gypsum.

EFFECT: invention increases degree of recovery of obtained concentrate REE up to 98÷99 % at improvement of its quality, reduction or complete exclusion of waste water discharges by changing types of used reagents and modes of their application.

1 cl, 1 dwg