Continuous synthesis of calcium hydrogen phosphate dihydrate (DCPD) in an annular rotating flow loop reactor

Abstract

The synthesis of calcium hydrogen phosphate dihydrate (DCPD) involves a gas–liquid-solid three-phase slurry system that poses challenges for precise control using traditional batch reactors to produce crystals with controlled morphologies and particle sizes. In this study, an annular rotating flow loop reactor (ARLR) was developed to continuously synthesize DCPD. The unique internal loop and annular rotating flow field of the reactor delivered exceptional plug-flow characteristics, ensuring that the obtained DCPD exhibited a controlled morphology and particle size. The morphology of DCPD was adjusted to be bowknot-shaped (BS) agglomerate crystals, reaching a length of 120 μm and a D50 size of 70 μm. The ARLR can achieve long-term stable operation with high-solid holdup slurries, outputting up to 125 g/h by maintaining precise and controllable flow and mixing conditions. Notably, ARLR marked a significant advancement in processing high-solid-holdup slurries, offering the adaptability to adjust the geometric design for various slurry systems and forecasting promising prospects.