Vertical roller mill ground fly ash powder processing technology
Many people think that the fly ash is very thin, how the grinding mill? Practice has proved that the mechanical grinding is especially suitable for the coarse to fine ash gray, the effect is not very obvious. Even for a long time of superfine grinding and its pozzolanic Vertical roller mill activity is still low. This is because the root cause of low activity fly ash volcano ash is: low CaO content, high degree of polymerization (CaO/SIO2 about 0.8–1.2 oligomers, less than 10%), and lower content of Al2O3, soluble SIO2 powder with particle surface broken bond, O2-, Ca2+, Mg2+ and other active points less. Although the dissolution reaction of ultra-fine grinding can promote the soluble SIO2 and Al2O3, but for other important factors for improvement of micro depending on their arms, the pozzolanic activity of increase is limited.
The main chemical composition of fly ash were SiO2, Al2O3 and Fe2O3, high calcium fly ash contains more CaO. As early as in 1914, the vertical roller mill American Anon published “research” ash volcanic features, first discovered the oxides in fly ash has the characteristics of volcanic ash. Due to large quantities of cement and concrete with fly ash, therefore, its application has been the focus of research in the field of cement in china.
According to the relevant data show that the use of fly ash in concrete, has three main effects: the active effect of volcanic ash, cement hydration of Ca (OH2) to stimulate the activity of fly ash, the reaction of cementitious material by C-S-H gel based; shape effect, which determine the morphology of powder coal ash the beads, when the content is more than 50%, increased mobility, reduce the water consumption of concrete, improve the properties of concrete; micro aggregate effect, which is less than 45 m sieve residue powder can be filled in the pore of concrete, and Ca (OH2) reaction of the gel can be filled with tiny pores, so that the concrete more dense.
At present, with the development of economy, improvement of people’s awareness of environmental protection, recycling of fly ash recycle become the social issues of concern, the Henan Polytron Technologies Inc to develop a series of milling machine, the deep processing of fly ash, the fly ash after fine grinding mill, not only can accelerate the hydration rate of cement particles also, the spherical shell damage ahead of fly ash can be dense, accelerate the pozzolanic reaction of fly ash, so as to improve the early strength of cement. Fly ash and crude ash by vertical roller mill fine grinding to a certain fineness, made of fly ash admixture impermeability of concrete, not only can replace part of cement, coal, limestone and other electricity consumption, reduce the cost of concrete, Protect environment, but also can improve the later strength of the concrete, improve the work of the new mix of concrete, improve the durability of the concrete, the production of high performance cement.