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21

PRAYON PROCESSES

ONE-CRYSTAL PROCESS OR PH1

[ PRAYON HEMIHYDRATE 1-CRYSTAL ]

The reaction takes place in two stages.

The first stage takes place with a low but

positive sulphate level, while the second

stage operates with a higher sulphate

level. Perfect sulphate and temperature

control permit the filtration of a slurry

containing a highly stable hemihydrate

with low scaling properties.

THE MAIN CHARACTERISTICS OF

THE PROCESS ARE

+

simple and low-cost process

+

high-strength acid

RECOMMENDED FOR LOCATIONS

+

with low-cost rock

+

with low-cost sulphuric acid

+

with high-cost energy

+

where gypsum disposal is not a problem

Phosphate

Water

Phosphoric Acid 39 to 45% P

2

O

5

Calcium

Sulphate

Hemihydrate

H

2

SO

4

Reaction

Recycled Acid

Digestion

HEMIHYDRATE

Vacuum

Vacuum

Filter

Flash

Cooler

Optional

Flash Cooler