The phosphoric acid production in Morocco generates a large amount of phosphogypsum (PG) which is a significant source of environmental contamination. In this work, PG has been characterized by different analysis techniques that allow to study the effect of the impurities on its physical and chemical properties. Thus, a method to purify the PG from phosphates and fluorides was proposed in order to improve its quality and to make it usable in plaster and cement. The purification process consists to sieve PG under 200 μm and to treat it by sulfuric acid to dissolve the insoluble impurities. The obtained results show that the treatment of PG by sulfuric acid 20 and 50% at 60 °C for 2 h is sufficient to make it suitable for used in the plaster and the cement respectively.

The valorization of phosphogypsum (PG) into valuable products by aqueous solution is very interesting on the economic and environmental side. This paper proposes a simple and efficient procedure which allows converting PG waste into calcite and lithium sulfate monohydrate. This last is recommended in lithium batteries, while the calcite can be used in several industries and in the environment. The optimum conditions of PG conversion obtained at room temperature with exact stoichiometric proportions of PG and Li₂CO₃ and for concentration limit equal to 0.3 mol/l. The PG conversion is total after 1.5 h under these conditions.

The Na_1 + xTi_2 − xAl_x(PO₄)₃ (0.0 ≤ x ≤ 0.9) solid solution has been prepared as a polycrystalline powder. These compounds crystallise in the NASICON type structure, Rc space group, and the crystal structures have been characterised by the Rietveld method with laboratory powder diffraction data. The Ti/Al atoms are randomly distributed over the octahedral site of the NASICON framework. The negatively charged framework is neutralised by the Na⁺ cations which are distributed over the M1 site, fully occupied, and M2 site, partly occupied. The cell parameter evolution along the series agrees with the substitution of larger Ti⁴⁺ by smaller Al³⁺ cations. The thermal expansion coefficients were determined from a thermodiffractometric study of Na_1.8Ti_1.2Al_0.8(PO₄)₃. The ion conductivity of the samples rises as the charge carrier number (x) increases. The activation energies deduced from the Arrhenius plots are close to 0.50 eV. The overall conductivities are near to 10⁻⁵ S cm⁻¹ at 200 °C.