H. El-shall et al., Effect of surfactants on phosphogypsum crystallization and filtration during wet-process phosphoric acid production, SEP SCI TEC, 35(3), 2000, pp. 395-410
A nonionic surfactant (CMR-100) containing a mixture of C-6-C-22 sorbitan e
sters was tested to improve the filtration rate of phosphogypsum produced f
rom a South Florida phosphate concentrate at different sulfate levels. Test
s were carried out on a lab-scale under operating conditions that simulate,
to a large extent, the industrial parameters. It was found that the mean d
iameter of the formed crystals was increased by addition of the surfactant.
Equally important, a narrower size distribution was obtained as compared t
o that in the absence of the surfactant. A significant increase (23 to 31%)
in filtration rate, expressed as tons P2O5/m(2).day, was achieved due to t
he surfactant's addition. A correlation between crystal size distribution o
f phosphogypsum and filtration rate is presented in this paper.