Synchronous activation of Si and Al in vanadium-bearing shale leaching residue via sodium carbonate additive

With increasing academic interest in geopolymers, research into the activation of geopolymer raw materials has become necessary. In this study, a novel activator sodium carbonate was used to activate vanadium-bearing shale leaching residues (VSLR). Under conditions of 15 wt% Na2CO3 addition, 450 °C activation temperature, and 60 min activation time, the (Si + Al) concentration in the activation residue leachate reached 1350.2 mg/L, which represents an increase of roughly 30% compared to that obtained by adding NaOH under the same conditions. Through thermodynamic and phase transformation analyses, it was found that the crystal minerals containing Si and Al in VSLR were synchronously activated at a lower temperature due to the presence of sodium carbonate. Therefore, the activation efficiency of Si and Al in VSLR was greatly improved and energy consumption reduced. The novel activator sodium carbonate is practically feasible, easy to operate, and highly efficient for VSLR activation compared to the traditional activator sodium hydroxide.