Rapid solidification of Sr-contaminated soil by consecutive microwave sintering: mechanism and stability evaluation

Consecutive microwave sintering is a method proposed in this study to dispose soil contaminated by Sr during a nuclear accident by rapidly solidifying the contaminated soil. The results show that soil contaminated with 20 wt% SrSO₄ and 30 wt% SrSO₄ can be completely solidified by microwave sintering at 1100-1200 and 1300 ℃, respectively, for 30 min. Sr was found to be cured into slawsonite (SrAl₂Si₂O₈) and glass structures. Moreover, soil sintered at 1300 ℃ has large cured solubility (30 wt.%), good uniformity, and excellent hardness (6.9-7.2 GPa) and chemical durability (below 1.46 × 10^-5 g m^-2 d^-1 at 28 d). Thus, consecutive microwave sintering technology may provide a new method for treating Sr-contaminated soil in case of a nuclear accident emergency.