Leaching of SYNROC-C: Relation to Microstructures

Soxhlet-type leaching experiments were carried out for SYNROC-C specimens synthesized by three different methods; hot uniaxial pressing, hot isostatic pressing, and atmospheric sintering. The leaching solutions were analyzed by inductively coupled plasma spectroscopy and atomic absorption spectroscopy. When elements such as sodium, cesium, and molybdenum contained in the glass phase of SYNROC-C, they are leached preferentially at the initial stage of leaching. The difference in elemental mass loss between the three SYNROC-C specimens (10 to 10² g/m²) depends mostly on the amount of preferential leaching. The release of the above elements is controlled by preferential leaching at the initial stage and then by diffusion through the host crystalline phases. The other elements not found in the glass phase can mainly be controlled by diffusion.