How to reduce sulfur trioxide in fly ash
The coal-fired units put into operation in China in recent years are all circulating fluidized bed units, and the content of sulfur trioxide in fly ash generally exceeds 3%. It is larger than the requirements of "fly ash for cement and concrete" (gb1596 -2004) and cannot be used in concrete, which greatly limits the application range of fly ash. It is of great significance to reduce the content of sulfur trioxide in high sulfur fly ash and expand the application range of fly ash. In the fly ash produced by circulating fluidized bed, the existing form of sulfur trioxide is mainly calcium sulfate. When mixed into concrete, some will generate hydrated calcium sulphoaluminate crystals (i.e. ettringite), which contain a large amount of crystal water, increasing the volume of cement by more than 115 times, resulting in concrete cracking; Some will precipitate gypsum crystals, the volume will increase by 1.24 times, and the cement stone will crack due to excessive stress. In order to ensure the construction quality of concrete engineering, gb1596 - 2004 requires that the sulfur trioxide content of grade I, II and III fly ash used for concrete shall be less than 3%, otherwise it is unqualified. In order to reduce the content of sulfur trioxide in fly ash, the author developed a high-efficiency sulfur removal agent for fly ash, which has been applied in production and achieved satisfactory results.
1 Experiment
The main raw materials used in the experiment include: fly ash from xiajiangbei power plant in Yibin, commercial ordinary sulfur removal agent, self-made fly ash * * high-efficiency sulfur removal agent (including sulfur trioxide scavenger, synergist, stabilizer, dispersant, penetrant, antioxidant, etc.). The experimental process includes wet method and dry method
Experimental process flow
The fineness, water demand ratio, loss on ignition, water content, sulfur trioxide and 28 day compressive strength ratio shall be tested according to gb1596 - 91.
2 results and discussion
2.1 the experimental results of removing sulfur trioxide with fly ash * * sulfur remover are to investigate the removal effect of fly ash * * sulfur remover on sulfur trioxide, treat high sulfur fly ash with the same quality and process as ordinary sulfur remover, test according to gb1596 - 91, and compare with blank ash samples.