Activation of Ca(OH)(2) using different siliceous materials

Siliceous materials such as silica fume, bentonite and diatomite were mixed with Ca(OH)(2) and hydrated at different conditions to produce reactive SO 2 sorbents. Two different hydration methods were used; namely atmospheric a nd pressure hydration. The effects of the hydration temperature, time and s iliceous material/Ca(OH)(2) weight ratio on the physical properties of the activated sorbents were investigated. A statistical design technique was ap plied by use of a two-level factorial design matrix to interpret experiment al results. In atmospheric hydration, it was found that increasing the temp erature and hydration time caused an increase in the total surface area of the sorbents. But, increasing the siliceous material/Ca(OH)(2) weight ratio caused a decrease in the total surface area of the sorbents. Thee relative surface area increments of sorbents are also influenced by the chemical co mposition of the siliceous material. In pressure hydration, mathematical an alysis showed that the surface area of the activated sorbents was positivel y affected by the hydration variables. The activated sorbents were characte rized by using thermogravimetry, x-ray diffractometer and scanning electron microscope, Thermogravimetric measurements showed that increasing the amou nt of reacted Ca(OH)(2) during hydration, which was presumably converted to Ca-containing reactive speciesies caused an increase in the surface area o f the sorbent. X-ray diffraction studies also indicated that calcium silica te hydrates were the principal Ca-containing species formed during hydratio n.