REE content of phosphogypsum from Romania

Phosphogypsum is a technogenic product remaining after the extraction of phosphoric acid from raw phosphate, mainly apatite. The original phosphate rock contains large amounts of REE, mainly replacing Ca from apatite or included in other phosphate structures. About 70% of the REE contents are stacked in the phosphogypsum obtained after sulfuric attack of the raw phosphate and much less in the case of hydrochloric attack. In Romania, the sulfuric attack through the hemidihydrate (HDH) or dihydrate (DH) procedures was extensively used to obtain phosphoric acid at Turnu Măgurele (TM), Valea Călugărească (VC), Năvodari (N) and Bacău (B). Inductively coupled plasma - atomic emission spectrometry (ICP-AES) analyses performed on selected samples of phosphogypsum from the four deposits showed that the contents in the main REE (cerium, erbium, neodymium, thorium, ytterbium) are specific for the phosphogypsum issued from the processing of sedimentary raw phosphates.