Increasing the utilization potential of fly ashes from fluidized bed combustion by mechanical treatments

Ohenoja, Katja; Körkkö, Mika; Wigren, Valter; Österbacka, Jan; Illikainen, Mirja

doi:10.1007/s13762-018-1812-x

Cited by 7 publications

(8 citation statements)

References 25 publications

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“…The air jet classification method (Multiprocessing System, Hosokawa Alpine, Augsburg, Germany) was used to fractionate fly ash samples into fine and coarse fractions, as presented in [30]. Classification rotor speed of 2000 rpm and air flow of 75 m 3 /h was used, and fine material shares from 15 to 30% were achieved depending on the fly ash.…”

Section: Classificationmentioning

confidence: 99%

“…Through air jet classification, the FBC fly ash utilization potential for concrete use can be increased significantly. Air jet classification is an efficient separation process that separates components into fine and coarse fractions so that hazardous components tend to concentrate to a fine fraction [30]. According to mass balance, when some elements concentrate to a fine fraction, other elements must concentrate to a coarse fraction.…”

Section: Classification Of the Fly Ashesmentioning

confidence: 99%

“…According to mass balance, when some elements concentrate to a fine fraction, other elements must concentrate to a coarse fraction. The work of [30] showed that when FBC fly ashes are classified with air jet classification, CaO is concentrated to a fine fraction, whereas SiO 2 and Al 2 O 3 are concentrated to a coarse fraction. Both sulfate and chloride have been found to concentrate to a fine fraction with high selectivity, which means that if mass share for fine fraction is 20%, up to 70% of the total sulfate and chloride content can concentrate to a fine fraction [30].…”

Section: Classification Of the Fly Ashesmentioning

confidence: 99%

“…The work of [30] showed that when FBC fly ashes are classified with air jet classification, CaO is concentrated to a fine fraction, whereas SiO 2 and Al 2 O 3 are concentrated to a coarse fraction. Both sulfate and chloride have been found to concentrate to a fine fraction with high selectivity, which means that if mass share for fine fraction is 20%, up to 70% of the total sulfate and chloride content can concentrate to a fine fraction [30]. The removed fine material share depended on the original fly ash properties, i.e., particle size and shape: with the used classification parameters (rotor speed of 2000 rpm and air flow of 75 m 3 /h), fine fraction removal was 15% from FA1, 31% from FA2, and 22% from FA3.…”

Section: Classification Of the Fly Ashesmentioning

confidence: 99%

“…Therefore, mechanical classification is one interesting option to improve fly ash chemical composition without the use of water, as there is a relationship between fly ash particle size and heavy metal, Cl − and SO 4 2 content [23][24][25][26][27][28][29][30][31]. It has been found that the utilization potential of fly ash from biomass and waste combustion can be significantly improved with mechanical classification [30]. However, the particle size distribution of classified coarse fraction and its behavior as a cement replacement material is not studied.…”

Section: Introductionmentioning

confidence: 99%

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Mechanically Treated Fly Ash from Fluidized Bed Combustion of Peat, Wood, and Wastes in Concrete

Ohenoja

Wigren²,

Österbacka

et al. 2019

Waste Biomass Valor

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Fly ash generation in fluidized bed combustion (FBC) is a critical issue in many countries due to its disposal is becoming increasingly restricted and expensive. Because of this, there is a demand for applications in which these types of fly ashes could be utilized efficiently. One promising use for FBC fly ashes is as a cement replacement material in mortar and concrete. The current concrete regulations do not allow the use FBC fly ash as a supplementary cementitious material, but it can be expected to be included in the standards in the future. The properties of FBC fly ashes typically do not fulfill the values set in the standards as such. This study aimed to establish whether the properties of fly ashes from FBC of peat, wood, and wastes can be modified by mechanical classification and grinding so that they meet the requirements of the standards. The sulfate and chloride content, the sum of the main components (Si, Al, Fe), and the fineness of material were analyzed before and after the classification and grinding processes. In addition, the mortar specimens were prepared by using the processed fly ash as a cement replacement material. It was found that air jet classification is an effective fractionating method for fly ashes that effectively removes sulfate and chloride into fine fraction. Classified and ground fly ashes are potential alternative cement replacement materials. It is possible to achieve 80% of the control sample's compressive strength and 90% of the control sample's flexural strength for mortars containing 20% of classified and ground FBC fly ashes. Graphical AbstractLow utilization potential fly ash Fine fraction: 10 -30% fly ash~ Hazardous components: heavy metals, SO 4 , Cl Coarse fraction: 70 -90% fly ash C hemical composition fulfills EN 450-1 concrete standard Waste disposal stabilization Grinding High value product, e.g. for concrete air air Air jet classificationThis study aimed to establish whether the utilization potential of fly ashes from FBC of peat, wood, and wastes can be improved in concrete by mechanical classification and grinding, which is not done earlier. We found that it is possible to modify these fly ashes to fulfill concrete standards. Usually it is thought that fly ashes from fluidized bed combustion are not suitable for standardized concrete, but this study shows that with treatments it is possible.

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Section: Classificationmentioning

confidence: 99%

Section: Classification Of the Fly Ashesmentioning

confidence: 99%