Influence of silica fume on radioactive fluoride concentrate liquid waste solidified by magnesium potassium phosphate cement

This paper investigated the influence of silica fume on radioactive fluoride concentrate liquid waste cementation with magnesium potassium phosphate cement (MKPC). The results showed that when the silica fume mass fraction increased from 0 to 20%, the setting time and fluidity of the MKPC slurry decreased, while the 28-day compressive strength of the solidified form increased. The main hydration products were MgKPO 4 ·6H 2 O and magnesium silicate hydrate (M–S–H). Silica fume had good physical adsorption of cesium, whose 42-day cumulative leaching fraction decreased from 0.083 ± 0.003 to 0.044 ± 0.002 cm. The formation of magnesium fluosilicate and its hydrate led to a decrease of fluorine leaching.