Wyniki wyszukiwania - BazTech

Ograniczanie wyników

1 Polish Journal of Chemical Technology

1 2012

Znaleziono wyników: 1

Liczba wyników na stronie

Wyniki wyszukiwania

Wyszukiwano:
w słowach kluczowych: calcium hemihydrate

Sortuj według:

Ogranicz wyniki do:

Studies on the transformation of calcium sulphate dihydrate to hemihydrate in the wet process phosphoric acid production

Grzmil B., Kuc B., Żurek O., Kubiak K.

Polish Journal of Chemical Technology

2012

Vol. 14, nr 2

80-87

The influence of the process temperature from 85°C to 95°C, the content of phosphates and sulphates in the wet process phosphoric acid (about 22-36 wt% P2O5 and about 2-9 wt% SO42-) and the addition of ?CaSO4ź0.5H2O crystallization nuclei (from 10% to 50% in relation to CaSO4ź2H2O) on the transformation of calcium sulphate dihydrate to hemihydrate has been determined. The wet process phosphoric acid and phosphogypsum from the industrial plant was utilized. They were produced by reacting sulphuric acid with phosphate rock (Tunisia) in the DH-process. The X-ray diffraction analysis was used to determine the phase composition and fractions of various forms of calcium sulphates in the samples and the degree of conversion of CaSO4ź2H2O to ?CaSO4ź0.5H2O and CaSO4. It was found that the transformation of CaSO4ź2H2O to ?CaSO4ź0.5H2O should be carried out in the presence of ?CaSO4ź0.5H2O crystallization nuclei as an additive (in the amount of 20% in relation to CaSO4ź2H2O), at temperatures 90š2°C, in the wet process phosphoric acid containing the sulphates and phosphates in the range of 4š1 wt% and 27š1 wt%, respectively.