Correlation analysis of various characteristics of fly ash based on particle separation

Abstract

Due to the diversity of fly ash particles, it is a scientific way to promote the comprehensive utilization of fly ash with high efficiency to sort and classify the particles. The correlation between sorting indices and various characteristics of fly ash is the theoretical basis for its separation and classified application. In this paper, fly ash from three different coal-fired power stations is separated according to particle size and apparent density. The composition, morphology, and pozzolanic activity of the separated fly ash particles were characterized by several test techniques including X-ray fluorescence, X-ray diffraction, polarized light microscopy, scanning electron microscopy and lime absorption test. The correlation laws between different characteristics common to three types of fly ash were analyzed. The results show that the alkaline oxide (CaO+MgO+K2O+Na2O) content of fly ash varies accordantly with particle size, apparent density, glass phase content and pozzolanic activity. 40 µm and 80 µm are the critical particle size for the obvious change of glass phase content and microstructure of fly ash particles, and 2.5 g·cm−3 is the critical apparent density for the change of phase composition. Pozzolanic activity is determined together by alkaline oxide content and acid oxide (SiO2 +Al2O3) content, and there is no obvious single factor relationship between pozzolanic activity and particle size or apparent density.

Keywords

• Fly ash
• Particle separation
• Particle size
• Apparent density
• Pozzolanic activity