Valorization of phosphogypsum waste as K2SO4 fertilizer and portlandite Ca(OH)2

Phosphogypsum Conversion into Calcium Fluoride and Sodium Sulfate

“…For the sulfate ions, the bands appeared at 1101 and 1003 cm -1 are assigned to the symmetric and asymmetric stretching of SO4 2respectively. The two bands observed at 666 and 598 cm -1 correspond to the bending of SO4 2-[2, [14][15][16][17].…”

“…produce calcium hydroxide (Ca (OH)2) and alkaline sulfates, according to the following reaction [16,17]:…”

“…Several factors affect on these reactions (3 and 4), such as: (i) the nature of the PG used (sedimentary, igneous, sieved, purified…); (ii) the molar ratio between PG and reagents; (iii) the temperature and pressure of the mixture; and (iv) the duration of the conversion reaction [12][13][14][15][16][17].…”

“…In the light of these processes (3, 4 and 5), the purity of the obtained calcium compounds (CaCO3, Ca (OH)2 and CaF2) are about 96, 95 and 93% respectively. These rational percentages are due to the presence of the insoluble impurities, which the most of them pass into the resulting calcium precipitates [6,7,[12][13][14][15][16][17][18]. For the radioactivity, the results of several works carried out on the radioactivity of PG and the resulting products show that these compounds could be considered as naturally occurring radioactive material (NORM).…”