Application of Pressurized Fluidized Bed Combustion ash to Phosphorous Adsorbent
Mio SHIRAKAWA and Haruhisa SHIOMI
Abstract:Typical calcium silicate powder, wollastonite, was mechano-chemically activated in air for 24h with a vibration ball-mill. The cakes of the vibration ball-milled wollastonite added with a fair amount of water and Pressurized Fluidized Bed Combustion (PFBC) ash were carbonated at 80 in 0.33MPa CO2 for 3h. The removal efficiencies of phosphorous for the carbonated specimens were investigated by immersing them in Na2PO4 aqueous solution containing 5ppm phosphorous. After immersing the specimens for prescribed duration in the test solution, the remaining amount of phosphorous in a supernatant liquid was measured by an inductively coupled plasma spectroscopy or a molybdenum blue method. Ca ion concentrations dissolved from specimens were measured with a selective electrode instruction. The addition of PFBC ash containing calcium sulfate increased a pore volume of the consolidated wollastonite by carbonation and the Ca ion released into water. As a result, the removed efficiencies of phosphorous for the specimens markedly improved compared with those without PFBC ash. The removed rate of phosphorous showed large temperature dependence, and crystallization process are thought to be the rate determining one of the phosphorous elimination. Key Words:Calcium silicate, mechano-chemistry, Carbonation, Phosphorous, Wollastonite, PFBC ash