Ceramics-Silikáty 54 (2) 152-159 (2010)

ANHYDRITE BINDER CALCINED FROM PHOSPHOGYPSUM

V. Leškevičienė, D. Nizevičienė

The phosphogypsum – dihydrate calcium sulphate is waste material of phosphoric acid production from the Kola apatites. The possibility of applying lime neutralized phosphogypsum as a raw material for obtaining anhydrite binder was investigated in this paper. The effect of the calcination temperature and of following additives: dust from a cupola furnace, ground glass and clay on the properties of obtained product was studied. The products were characterized by X–ray diffraction analysis, simultaneous thermal analysis, Fourier-transform infrared spectroscopy (FT-IR) and scanning electron microscopy (SEM) analysis. It was determined that the phosphogypsum with additives calcined at the temperature 900ºC, and the following grinding of it to the specific surface area 600 ± 10 m²/kg allow obtaining the fast setting anhydrite binder. The anhydrite binder calcined with the addition of 5% ground glass exposes the best physical and mechanical properties: the setting duration up to 13-38 min, the compressive strength of the dry samples is 30.74 MPa.

Keywords: phosphogypsum, neutralized phosphogypsum, anhydrite binder, calcined, additives