Reactivity of fly ashes milled in different milling devices

Abstract

The effect of two different milling devices, namely attrition mill versus vibration mill, on the reactivity of fly ash was studied. High calcium fly ash from 4th Thermal power station of Ulaanbaatar (Mongolia) was used for the experiments. The raw and processed samples were characterized by XRD, SEM, Particle size distribution, BET, Blaine surface area and density measurements. The efficiency of 1 hour milling was evaluated with the Blaine surface area set to be more than 5000 cm2/g. The physical and chemical properties of the attrition milled fly ash changed not much compared to the vibration milled samples. For example the d50 particle size became reduced from 29 µm to 6 µm by attrition milling and in vibration milled fly ash it was reduced to 7 µm. The density increased from 2.44 g/cm3 of raw fly ash to 2.84 g/cm3 and 2.79 g/cm3 in attrition and vibration milled samples, respectively. Mechanical milling revealed not only a particle size reduction but also the formation of a denser microstructure. As a result the vibration milled fly ash showed a weaker interaction with the alkaline solution (8 M NaOH used here) compared to the attrition milled fly ash. Consequently, compressive strength of the binder prepared using the attrition milled fly ash was higher, 61 MPa, while for vibration milled fly ash it was 49 MPa. For comparison unmilled fly ash, it was 21 MPa.

Effect of cinnamon essential oil on morphological, flammability and thermal properties of nanocellulose fibre–reinforced starch biopolymer composites

“…The materials were characterized by X-ray diffraction (XRD) and Fourier transforms infrared (FTIR), and the materials showed great potential in nanocomposite industry. Similar work was represented by Chu et al [25] on fly ashes and was also characterized using XRD, FTIR and scanning electron microscopy (SEM), which showed promising results. This shows that natural fibre had many advantages to be used in various applications.…”

Mechanochemically Assisted Coal Fly Ash Conversion into Zeolite

“…This transformation is in line with the PSD and SBET results for milled FA. Chu et al [ 36 ] also confirmed high content of finer particles within the milled FA samples and indicated only a slight particle shape difference between various milling devices (attrition and vibration mill).…”

Microstructural and thermal characterization of concretes prepared with the addition of raw and milled fly ashes

“…Therefore, for the present research was used fly ash milled by the attrition mill. The activation of the fly ash is described elsewhere [18]. With attrition milling the average particle size was reduced from 29 to z6 mm and density was increased from 2.44 to 2.84 g/cm 3 .…”

“…An improved reactivity with alkaline solution was reported for attrition and vibration milled fly ashes [18]. It was suggested that the attrition mill is a more suitable device for fly ash activation than the vibrating mill.…”