Process for valorizing phosphogypsum as a material for manufacturing plaster and bricks.

Abstract

The invention relates to a process for valorizing phosphogypsum as a material for manufacturing plaster and building bricks. Regarding brick manufacturing, several formulations have been proposed allowing for the widespread use of phosphogypsum; the lime fixation point (PFC) was the criterion for optimizing the mixtures. Washing the phosphogypsum resulted in a decrease in conductivity and an increase in pH (from 2.5 to 6.48 after three washes). This indicates a reduction in pollutants, particularly soluble pollutants such as acid residues. For the production of phosphoplaster, the raw phosphogypsum is washed until a paste with a pH of 6 is obtained. Calcination of the washed phosphogypsum for five hours yielded the phosphoplaster. To perform a comparison, the 4cm*4cm*16cm test specimens made of phosphoplaster are kept in the air and another part is mixed with 3% CaO before being dried.