Synthesis of monolithic tobermorite from blast furnace slag and evaluation of its Pb removal ability

Abstract

Synthesis of aluminum substituted tobermorite from blast furnace slag was attempted. Mixture of blast furnace slag and quartz controlled Ca/(Al+Si) ratio for 0.8 to 1.0 was treated by a rotary hydrothermal treatment for 24 h at 453 K. Obtained samples were characterized by X-ray diffraction (XRD) and scanning electron microscope (SEM) observation. Monolithic tobermorite was successfully synthesized with 0.8 of Ca/(Al+Si) ratio by this rotary hydrothermal treatment, whereas monolithic tobermorite could not be synthesized by the conventional static hydrothermal treatments, leading to the mixture of tobermorite and other calcium silicate containing unreacted SiO₂. Pb removal ability was investigated for this monolithic tobermorite obtained by this rotary hydrothermal method from blast furnace slag. It was found that monolithic tobermorite had a good Pb removal ability. This result shows that the synthesis of tobermorite is useful as a recycle of blast furnace slag.