Author(s)

Agata Mazienczuk, Andrzej Matynia, Krzysztof Piotrowski, Boguslawa Wierzbowska

Silesian University of Technology, Department of Chemical & Process Engineering, Gliwice, Poland.
Wroclaw University of Technology, Faculty of Chemistry, Wroclaw, Poland.

Reaction crystallization of struvite in water solutions containing 0.20 mass % of phosphate(V) ions by magnesium and ammonium ions addition was investigated experimentally. Process was carried out in DTM type crystallizer with liquid jet pump device in 298 K assuming stoichiometric conditions. Struvite crystals of mean size L_m 5.2-23.0 μm were produced depending on pH (9-11) and mean residence time of suspension in a crystallizer τ (900-3600 s). Under these conditions linear growth rate of struvite crystals (SIG MSMPR kinetic model) decreased 2-time with the increase in pH and 3-time with the elongation of mean residence time of crystal suspension from 7.11×10^-9 m/s (pH 9, τ900 s) to 1.65×10^-9 m/s (pH 11, τ3600 s). Nucleation rate varied within the 7.9×10⁸-1.8×10¹⁰ 1/(sm³) limits. Struvite product of maximal linear size exceeded 100 μm with 10 vol. % of < 3 μm fraction corresponded to pH 9 and τ3600 s.

Struvite; Crystal Size Distribution (CSD); Reaction Crystallization Kinetics; Continuous DTM Type Crystallizer; Jet Pump

A. Mazienczuk, A. Matynia, K. Piotrowski and B. Wierzbowska, "Continuous Reaction Crystallization of Struvite in a DTM Type Crystallizer With Jet Pump of Ascending Suspension Flow in a Mixing Chamber–Kinetic Approach of the Process," Journal of Crystallization Process and Technology, Vol. 2 No. 3, 2012, pp. 96-104. doi: 10.4236/jcpt.2012.23012.