Prospects of recycling used plaster of paris – short review

Abstract

Plaster of Paris (POP- CaSO4. 0.5H2O) is used for various applications, such as in the ceramic industry, where it serves as a crucial component in crafting moulds and cementitious materials used in construction projects such as wall plaster, wall boards, and gypsum blocks. The dental industry uses POP for mounting casts or models of oral tissues. POP is commonly used in orthopaedic applications to support fractures for broken bones, making positive casts/models for fabricating mobility assistive devices. Demand for POP is continuously increasing with the expansion of the mentioned industries. Notwithstanding this sizable market, POP disposal has become a serious concern. Conventional POP disposal techniques, such as burning and dumping in landfills, negatively impact the environment by causing groundwater contamination, air pollution, disturbance of habitats, and land use issues. In this regard, this review focuses on the possible recyclability of POP. POP recycling is typically done by calcining used POP at relatively higher temperatures (150-1800C), where dehydration of used POP (CaSO4.2H2O) becomes recycled POP (CaSO4.0.5H2O). Many other factors, such as temperature and curing time, particle size, sample size, POP-to-water ratio, method of recycling, and secondary additives, affect the quality of recycled POP. Recycling reduces the need for virgin materials, conserves natural resources, and minimizes the environmental impact of extraction and production, encouraging the circular economy.