From Lab to Plant: First Industrial Experience of the New High Efficiency Dihydrate Hemihydrate Process (DA-HF) Process

• Published in: Procedia engineering Vol. 83; pp. 181 - 187
• Main Authors: Theys, Tibaut, Fati, Dorina, Schrevens, Olivier, Tarnowska, Agata, Zienkiewicz, Monika
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 2014
• Subjects: dihydrate; Filtration; Hemihydrate; phosphoric acid processes; dihydrate; Hemihydrate; phosphoric acid processes; Filtration
• ISSN: 1877-7058; 1877-7058
• DOI: 10.1016/j.proeng.2014.09.036

During the first edition of Symphos, Prayon presented a newcomer in the family of phosphoric acid processes: the Prayon Dihydrate Attack – Hemi Filtration process (DA-HF). In this process all the dihydrate slurry from attack tank is converted into hemihydrate before filtration. Process conditions have been found such as to make possible phosphoric acid production directly from hemihydrate conversion tank. Based on pilot test results with more than 6 different phosphate rocks, with this process P2O5 recovery gains of about 1,5% - 2% were expected with respect to a dihydrate process. Slurry filterability is also improved by about 10% - 20% and P2O5 content of the produced acid is increased by more than 6% compared to a Dihydrate process. Based on such promising results Grupa Azoty and Prayon Technologies decided to join their forces to run two industrial tests in Grupa Azoty plants. One of the Dihydrate production plant was converted into DA-HF process by simple modifications, including piping modifications, pump addition, steam and sulphuric acid injection pipes installation. During the tests, Egyptian and Moroccan rocks were processed successfully. The joint project team showed that the process is stable, it can be stopped and started easily. The efficiency obtained is about 97,5% with Morocco rock and the P2O5 produced above 33%. This corresponds to an impressive gain in efficiency of about 4% P2O5 compared to the dihydrate process. The results obtained being very promising, Grupa Azoty and Prayon Technologies have agreed to move forward studying the conversion of one Grupa Azoty production plant into this new recently patented technology. Grupa Azoty, in cooperation with Prayon, is preparing to change the technology of phosacid production from DH to DA-HF. As a next step in this project feasibility study, including process and technical issues, is being prepared.