Abstract SYMPHOS 2011

NEW DEVELOPMENTS IN DIHYDRATE-HEMIHYDRATE PROCESSES
Tibaut THEYS
Prayon Technologies, Process Manager
PH-O-03
Prayon has more than 30 years industrial experience in the double crystallisation, double filtration dihydratehemihydrate
process (Central-Prayon Process, CPP). The industrial performances are a P2O5 yield higher than 98%
and production of 32% -37% P2O5 acid. Furthermore, the hemihydrate produced is more ecological (purer and
drier) than classical gypsum.
Recently some variations of the Dihydrate-Hemihydrate have been developed.
In the so-called Mixed process, part of the slurry from the dihydrate attack is converted into hemihydrate by
addition of sulphuric acid and steam. The resulting hemihydrate slurry is filtered together with the dihydrate slurry.
This partial conversion increases the P2O5 yield with respect to dihydrate process and the mixture hemihydrate/
dihydrate discharged from the filter is drier than gypsum.
Other developments of the Dihydrate-Hemihydrate process will be described.
Based on pilot test results, yield improvements of about 2% can be expected with respect to dihydrate process.
The above processes (CPP, Mixed, etc) will be described in some detail in this paper and compared to classical
dihydrate and hemihydrate processes in terms of performances.
Biography
He graduated as a Biochemical Engineer at the University of Louvain in Belgium. He joined Prayon Technologies
Company in 1995. After 6 month in production, he joined the licensing division. He participated during three years
to the study, the pilot tests, the construction, the training of operators and the start-up of a purified acid plant in
Morocco. In 1998, He joined the Fertilizer grade Phosphoric acid team to perform the same type of activities.
In 2002 he was the Commercial Manager of Prayon Technologies; the technologies offered include Phosphoric acid
and related technologies along with Profile, an other division of Prayon, for the fabrication equipment as filters,
agitators droplets separators and so on.
In 2004 he joined CYTEC as a Project Manager and Maintenance Specialist. He managed revamping projects of three
production units and improved the reliability of these plants. In 2006 he joined De Smet Engineers and Contractors,
an EPC company specialised in the supply of turn key plant, as Project Manager. He worked in the commercial team
as a Business Development Manger. He developed the biomass business division.
In 2010 he joined back Prayon as a Process Manager. He works on the technical and commercial development of
new and existing phosphoric acid technologies.
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