Abstract: In this paper, high calcium fly ash (HCFA) from circulating fluidized bed (CFB) boiler calcined at low temperature was disposed by means of adding digesting agent, grinding and filling dispersing agent to digest the free-CaO inside it. The content of free-CaO in HCFA dealt by different means was tested, and the micro-structure and appearance of HCFA particles before and after disposal were observed by SEM. The results indicated that without filling dispersing agent, digesting of free-CaO was influenced by the amount of digesting agent mostly, then particle size of HFCA, and at last the digesting time. With the aid of dispersing agent, more water got into HCFA particles and the digesting of free-CaO was accelerated. SEM pictures revealed that abundant Ca(OH)_2 with hexagonal flakes, plates and column appearance came into being on the surface of particles after HCFA dealt with digesting agent,while fine Ca(OH)_2 crystal clusters emerged inside the particles of HCFA after this material was digested both with digesting agent and dispersing agent.

Key words: HCFA%digesting of free-CaO%digesting agent%grinding%dispersing agent