Mr Amirhossein Jooypa, Dr Mehdi Irannajad, Dr Akbar Mehdilo, Mr Reza Kouchakzadeh, Mrs Shiva Nazari,
Volume 32, Issue 4 (12-2024)
Abstract
The tailings come from Chadormalu iron ore processing plant is beneficiated by flotation method. The obtained apatite concentrate is dissolved in acidic media and used to produce phosphoric acid. The chemical analysis shows that the phosphoric acid solution contains 75 ppm of arsenic (As) and 313 ppm of Rare Earth Elements (REE). To identify the source of As and REE, the samples taken from flotation feed (tailings of high intensity magnetic separator), flotation tailings, and apatite concentrate were characterized mineralogically using XRD, XRF, ICP-OES, and scanning electron microscopy (SEM) equipped with EDX and WDX. The results revealed that the concentrate containing 35.6% P2O5 is mainly composed of fluorapatite mineral and a small amount of dolomite and calcite. ICP analysis showed that the As and REE contents in the apatite concentrate are 345 ppm and more than 5000 ppm, respectively. Through the SEM studies, it was identified that some parts of REE have been placed in the fluorapatite lattice as substituting for calcium, and the other part is in the form of monazite minerals with dimensions finer than 20 microns. It was also revealed that As is probably substituted for phosphorus (P) in the lattice structure of fluorapatite and monazite minerals. Thus, it will not be possible to recover REE and As before dissolving the apatite concentrate. Therefore, REE must be recovered firstly from the solution by an appropriate method and then As to be separated from the solution by the precipitation method.
