Investigation on the effects of fluid intensification based preconditioning process on the decarburization enhancement of fly ash

Li, Danlong; Liang, Yannan; Wang, Hainan; Zhou, Ruoqian; Yan, Xiang-Ping; Wang, Lijun; Zhang, Haijun

doi:10.1016/j.cjche.2021.03.001

Cited by 7 publications

(7 citation statements)

References 47 publications

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“…Batch Floatation Test. Different results have been obtained for the different investigation about the effect of kerosene 27 and diesel 28 on the collection of unburned carbon. In addition, different studies of the effect of alcohol foaming reagents, including MIBC, 25 sec-octanol, 27 no.…”

Section: Resultsmentioning

confidence: 99%

“…Therefore, removing unburned carbon from fly ash is an important method for increasing the quality of fly ash and utilizing it . There are several technologies for reducing the LOI value of fly ash, such as fluidized bed reactors, oil agglomeration, , electrostatic separation, – and froth flotation. – Flotation is one of the most promising methods for removing unburned carbon from fly ash with high efficiency, effectiveness, and easy commercialization. , Some studies carried out for the removal of unburned carbon from fly ash by flotation are summarized in Table , which shows that the LOI value for different kinds of fly ash can be obviously decreased by flotation and meets the industrial standard. However, when considering the LOI of fly ash as the kernel problem, the recovery of unburned carbon and the quality of carbon concentrate were often neglected.…”

Section: Introductionmentioning

confidence: 99%

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Facile Route for Effective Separation and Full-Scale Recycling of Fly Ash and Unburned Carbon

Duan,

Zhang,

Cao

et al. 2024

ACS Omega

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The synchronous production of high-quality unburned carbon concentrate and cleaned ash from high LOI (loss on ignition) fly ash without yielding secondary solid waste is a dilemma issue. In this study, a viable flotation process with one rougher and two cleaners is developed for simultaneously obtaining carbon concentrate with a yield of 18.00% and an ash content of 17.49% and cleaned ash with a yield of 82.00% and a LOI of 4.63% from fly ash, reaching 84.72% of combustible substance recovery and 80.66% of flotation perfection index. The characteristic analyses of the stage by stage releasing products using laser particle size analysis, XRF, XRD, and SEM−EDS demonstrate that the inevitable factors that lead to a remaining higher ash content in the one-step flotation carbon concentrate are the random entrainment of mineral particles in the size range of 0−20 μm, especially the quasi-colloidal parts within 0−12.5 μm and the weak selective collection of fine-grained conjoined granules in the size range of 0−40 μm. Consequently, at least two cleaning steps are required for the effective separation of unburned carbon and ash. Furthermore, batch flotation test results show that diesel is superior to kerosene in the collection of unburned carbon, with an optimum dosage of 800 g/t; no. 2 oil acts more positively than MIBC for the separation of unburned carbon and ash, with an optimal dosing amount of 600 g/t; the optimum pulp concentration and flotation time are as follows: 100 g/L and 3.5 min for the rougher, 45 g/L and 2 min for the first cleaning, and 30 g/L and 3 min for the second cleaning. This study provides an economically feasible technological solution for the full-scale recovery of high-LOI fly ash in one step and avoids the problem of secondary solid waste that would have been generated in previous studies.

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Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Facile Route for Effective Separation and Full-Scale Recycling of Fly Ash and Unburned Carbon

Duan,

Zhang,

Cao

et al. 2024

ACS Omega

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“…Moreover, the collector molecules precisely prefer to associate with the hydrophobic surface, further enhancing the hydrophobicity of the surface. 16 The results of the flotation test were well supported by the contact angle tests, which demonstrated that the hydrophilic property of the unburnt carbon in CFA could be improved by prestirring.…”

Section: Flotation Test Resultsmentioning

confidence: 99%

“…As well, friction or shear forces produced when two particles or fluid components move at various speeds cause fine impurities to separate from the particle surface, exposing the natural hydrophobic portion of the unburned carbon. Moreover, the collector molecules precisely prefer to associate with the hydrophobic surface, further enhancing the hydrophobicity of the surface . The results of the flotation test were well supported by the contact angle tests, which demonstrated that the hydrophilic property of the unburnt carbon in CFA could be improved by prestirring.…”

Section: Resultsmentioning

confidence: 99%

“…Consequently, pulp stirring is crucial for the suspension and stirring of particles, dispersion of agents in the pulp, uniform stirring and collision of agents and particles, and effective adsorption . Although some articles have emphasized the influence of preconditioning on CFA flotation, most have focused on the study of the impact of prestirring speed on the flotation process. , However, prestirring time is one of the most critical parameters of the stirring operation, which is also among the major variables impacting the flotation results . Song et al indicated that prestirring time with a fixed stirring strength controlled the amount of kinetic energy input.…”

Section: Introductionmentioning

confidence: 99%

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Effect of Prestirring Time on Carbon Removal from Coal Fly Ash in the Flotation Technology

et al. 2023

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Coal fly ash (CFA) is one of the industrial byproducts of burning coal for energy production and has unburned carbon, which negatively affects its full potential use. The flotation technology can be effective in separating unburned carbon from CFA, and the prestirring time is crucial for the ideal initial conditions during the flotation process. To find the suitable prestirring time, eight prestirring times, including 0, 1, 2, 3, 4, 5, 6, and 7 min, were selected in this paper, followed by flotation of CFA after prestirring. Parameters such as loss on ignition (LOI), the removal rate of unburned carbon (RUC), contact angle, and particle size volume fraction were used to assess the effect of prestirring time on flotation results. The results showed that the prestirring time significantly affects the CFA flotation performance. As the prestirring time increased, the LOI of CFA first decreased and then increased, and the contact angle showed the opposite trend. Besides, the prestirring time of over 2 min positively affected the fineness of the tailings. Overall, the prestirring time of 3 min had the most significant carbon removal effect, obtaining an LOI of tailings of 0.96%, a yield of 74.56%, an RUC of 72.70%, and a volume fraction less than 45 μm of 36.65%. This study provides theoretical support for improving stirring efficiency and saving flotation costs in industrial applications and is conducive to the recycling of CFA resources.

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Effect of energy input on surface properties and dispersion of diaspore and kaolinite in flotation process

Yang,

Wu,

Chai

et al. 2023

Chemical Engineering and Processing - Process Intensification

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Investigation on the effects of fluid intensification based preconditioning process on the decarburization enhancement of fly ash

Cited by 7 publications

References 47 publications

Facile Route for Effective Separation and Full-Scale Recycling of Fly Ash and Unburned Carbon

Facile Route for Effective Separation and Full-Scale Recycling of Fly Ash and Unburned Carbon

Effect of Prestirring Time on Carbon Removal from Coal Fly Ash in the Flotation Technology

Effect of energy input on surface properties and dispersion of diaspore and kaolinite in flotation process

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