Effect of soil elements (Si, Al, and Ca) on the performance and structure of simulated An3+ radioactive contaminated soil by microwave sintering

Radioactive contaminated soil is a serious threat to environmental and health safety. In this work, the simulated An3+ radioactive contaminated soil samples were successfully immobilized with microwave sintering technology at 1300 °C for 30 min. The phase, microstructure, mechanical properties, and chemical durability of the simulated radioactive contaminated soil samples were investigated. The maximum solid solubility of moist soil, chernozem soil, saline-alkali soil and sandstorm soil were 22 wt.%, 29 wt.%, 20 wt.% and 20 wt.%, respectively. SEM-EDS results show that the 10 wt.% Nd2O3 doped soil sample was completely vitrified, and the element distribution was uniform. The density and Vickers hardness values of the solidified body were in the range of 2.25–3.20 g cm−3 and 6.48–8.88 GPa. The leaching rate of the solidified body was on the order of ∼10−7 g·m−2·d−1 at 28th days. In addition, the effects of silicon, aluminum and calcium in soil composition on the curing effect were studied. The soil with a high Al/Si ratio had higher solid solubility in the glass. Ca element would promote the formation of crystals, and the solid solubility of glass solidification decreases for soils with the high calcium content. However, these elements have no obvious effect on the mechanical properties of the solidified body. This study will provide basic data for the treatment of radioactive contaminated soil. •The vitrification of various soil samples simulated by An3+ radioactive contamination was successfully achieved.•The sintered sample with a higher Al/Si ratio has higher solid solubility.•The sintered sample with a higher Ca content may lead to a decrease in the bridging oxygen bond content, thereby reducing the stability of the solidified body.•The sintered sample has reliable mechanical stability and chemical durability.