Title: Flash Calcination for Recycled Gypsum Recovery

Author(s): Damien Gaudrel, Annabelle Phelipot-Mardelé, Christophe Lanos and Marie Glorennec

Publication: Symposium Paper

Volume: 349

Issue:

Appears on pages(s): 62-70

Keywords: calcination, gypsum, recovery, recycling

DOI: 10.14359/51732739

Date: 4/22/2021

Abstract:
Nowadays, recycling and recovery of construction waste are major environmental issues. Gypsum, which is widely used in construction industry, generates around 400 000 tons of waste per year in France. Thermal activation of gypsum is well known and controlled, especially for the implementation of plaster or anhydrite. This study focuses on the recovery by flash calcination of a recycled gypsum from a gypsum recycling factory, using a flash furnace prototype allowing adjustment of multiple calcination parameters. In order to compare the thermal activation behaviour of recycled gypsum, a “noble” gypsum, derived from a hydrated industrial gypsum plaster is also used. Different calcination temperatures allow to obtain multiphase products with different degrees of reactivity. The raw gypsums (recycled and noble) as well as calcined materials are characterized by XRD, TGA, and Helium pycnometry. The hydration reactivity and setting time of calcined products and mechanical performances are also evaluated. The results highlight a similar behaviour regarding the thermal activation by flash calcination between a noble gypsum and a recycled one. They also emphasize a high reactivity of some of the calcined products. This study leads to identify the calcination conditions usable to reach the different hydrated or anhydrous calcium sulphate phases. Carefully tailored calcium sulphate binder is then accessible from recycled material.