Alkali activation of sludges rich in silicon

The project aim is to valorize, through two distinct approaches, the inorganic material of the sludge resulting from silicon wafer waste-water processing. The first approach focuses on the recovery of the inorganic component via the alkaline activation of the sludge as obtained from the production plant. Specifically, an attempt has been made to use the sludge (especially the silicon as blowing agent and the Al2O3 as filler inert phase) as the main raw material for the production of low-cost and self-foaming materials. These materials, after a formulation development and an optimization of the foaming phase, will undergo various physical and chemical characterizations. The second approach considers that the sludge may be subjected to an additional thermal process in the future. This step is planned because it will decrease the fraction of organic matter, which is expected to make the sludge less susceptible to chemical activation. To prepare for this, a lab-scale simulation of the residual material obtained at the end of the thermal process have been conducted. Then, this post-heat treatment materials will be utilized to produce dense and alkali-consolidated materials, further enhancing the valorization of the inorganic components which characterize the sludge.