METHOD OF PHOSPHOGYPSUM PROCESSING Russian patent published in 2016 - IPC C22B3/08 C22B59/00 

FIELD: chemistry.

SUBSTANCE: invention relates to phosphogypsum processing. After water treatment phosphogypsum is leached with sulphuric acid with conversion of rare-earth elements concentrate and impurity components into solution. Washed phosphogypsum is neutralized to produce gypsum product. Sorption of rare-earth elements is carried out in two stages. At the first stage of sorption of part of the leaching solution is passed through sulfoxy cationite. That is followed by desorption to obtain primary calcium-thoric strippant. At second stage other leaching solution portion is passed through cationite sorption. Obtained secondary depleted sulphate solution is used for desorption to obtain secondary calcium-thoric strippant. Then, desorption and precipitation of rare-earth elements is conducted to separate precipitate. Obtained primary and secondary strippants are combined, additionally fortified with sulphuric acid to concentration of initial sulphuric acid solution is fluorine-containing compound in an amount sufficient for concentration of fluorine-ion of 20-50 mg/l, and directed in turn for leaching of new layer of phosphogypsum.

EFFECT: method enables to reuse at leaching formed strippants, to produce non-radioactive rare-earth concentrate and quality gypsum product.

1 cl, 4 ex