Effects of particle shaping on the performance of phosphorus building gypsum

Phosphogypsum (PG) is an industrial by-product from the wet preparation of phosphoric acid. Phosphorus building gypsum (PBG) can be obtained from PG after high-thermal dehydration. Improving the properties of PBG is of great significance to extending its application range. In this paper, PBG was modified by particle shaping, resultantly its properties have been significantly improved. This study utilized a small-scale ball mill as a power source for simulated shaping to investigate the shape parameters of PBG particles before and after shaping. Further, the effects of different material-to-ball mass ratios, ball milling speeds, and shaping durations on PBG performance were examined. Shaped PBG particles exhibited a reduction in aspect ratio, approaching a roundness of approximately 1. The sharp edges on the particle surfaces decreased, resulting in a particle appearance that tended to approach a spherical form. Moreover, when the material-to-ball mass ratio and ball milling speed were held constant, increasing the shaping duration decreased and then increased the water amount required for normal consistency and setting time of PBG. However, the strength, first increased and then decreased. Under the conditions of a material-to-ball mass ratio of 1:1, ball milling speed of 90 r/min, and a shaping duration of 5 min, PBG exhibited the most significant enhancement in mechanical properties. Finally, the mechanism of how particle shaping affects PBG performance was analyzed using the theory of water film thickness.