Removal of unburned carbon from fly ash using enhanced gravity separation and the comparison with froth flotation

Zhang, Ling; Yang, Fu‐Mei; Tao, Youjun

doi:10.1016/j.fuel.2019.116282

Cited by 41 publications

(14 citation statements)

References 31 publications

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“…In recent years, the decarbonization of fly ash has been a focus of research. Current common methods of reducing the unburned carbon in fly ash are dry separation (e.g., screening and friction electrostatic separation) and wet separation (e.g., foam flotation and gravity separation) [ 14 , 15 ]. Sieving exploits the size distribution characteristics of unburned carbon to achieve removal, as demonstrated by the measurable reduction of unburned carbon only in fine particles [ 16 ].…”

Section: Introductionmentioning

confidence: 99%

The Effects of Curing Temperature on CH-Based Fly Ash Composites

Takasu

Suyama

et al. 2023

Materials

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Curing temperature affects the compressive strength of cement paste systems via the pozzolanic reaction. However, different processes, climates, and weather conditions often result in different initial curing temperatures. The relationship between curing temperature and compressive strength is still an underexplored domain. To explore the effect of curing temperature on calcium hydroxide (CH)-based fly ash composites, fly ashes from different carbon sources were used to make CH-based composites, and the compressive strength, reaction rate, CH content, and C-S-H generation were analyzed. The correlation between the reaction rate and C-S-H content was analyzed. High-temperature curing improved the compressive strength of the cement paste system by affecting the CH-based reaction rate in the initial stage, with the highest initial reaction rate reaching 28.29%. However, after cooling to constant temperature, high-temperature curing leads to a decrease in CH and C-S-H content. The average decrease rate of calcium hydroxide content under high temperature curing is 38%, which is about 2.38 times that of room-temperature curing conditions. This led to a decrease in the compressive strength of the cement paste. Therefore, the performance of CH-based fly ash composites produced by low-temperature curing was superior to that of composites produced by high-temperature curing.

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Section: Introductionmentioning

confidence: 99%

The Effects of Curing Temperature on CH-Based Fly Ash Composites

Takasu

Suyama

et al. 2023

Materials

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“…[ 4,5 ] These residue carbon particles can be separated and recovered to prepare a catalyst with oxygen reduction reaction (ORR) activity through simple processing steps. [ 5 ]…”

Section: Introductionmentioning

confidence: 99%

“…Although the molten mineral and carbon particles adhere and infiltrate under the hightemperature conditions of the gasifier, forming patterns that are difficult to separate, the remaining carbon forms special carbon particles with a certain graphitization and pore structure due to the high temperature in the gasifier and the corrosion of the carbon particles during the gasification reactions. [4,5] These residue carbon particles can be separated and recovered to prepare a catalyst with oxygen reduction reaction (ORR) activity through simple processing steps. [5] The ORR occurs at the cathode of fuel cells and metal-air battery, but the ORR has the problems of slow kinetic reaction and a high energy barrier to the reaction.…”

Section: Introductionmentioning

confidence: 99%

Investigation of the Heteroatom Doping Effect on Gasification Fine Slag Residue Carbon Oxygen Reduction Reaction Catalysts

Wang

Gong

et al. 2023

Energy Tech

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Coal gasification fine slag (GFS) is a kind of solid waste that is produced from industrial entrained‐flow gasification plants. Using the GFS flotation residue as a carbon source for the oxygen reduction reaction (ORR) catalyst is therefore an effective recycling method that will gain great attention. Herein, the carbon residue after the flotation of GFS is used as the precursor to prepare ORR catalysts through CO2 activation. Combined with the characterization of Raman spectroscopy, X‐ray photoelectron spectroscopy, and scanning electron microscopy, the influence of N, P, Fe, Ca, and other doped elements on the physical and chemical structure of the catalyst is explored. The results demonstrate that calcium chloride causes the decrease of reactive nitrogen, and has a negative effect on the development of pore structure. The active nitrogen content of ammonium phosphate as a nitrogen source is lower than that of ammonium chloride as a nitrogen source. The codoping of ammonium phosphate and ferrocene produces a mutual inhibitory effect, resulting in lower doping levels of phosphorus and iron. This study has great significance for the activation and heteroatom doping treatment of ORR catalysts prepared from gasification residue carbon.

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“…The pretreatment of decarbonization and Fe removal is necessary to improve the whiteness of zeolite. At present, the method of decarbonization mainly includes froth flotation, 12 triboelectrostatic separation, 13 and calcination 14 . These methods could achieve high‐efficiency decarbonization, but they have the problem of complex processes and enormous energy consumption.…”

Section: Introductionmentioning

confidence: 99%

Synthesis of zeolite A with high whiteness from coal gangue by two‐step pretreatment method

Liu

Yan

et al. 2022

Asia-Pacific J Chem Eng

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The comprehensive utilization of coal gangue (CG) is restricted by color elements in CG including C and Fe x O y . The magnetic separation and hydrothermal acid leaching are combined to pretreat the solid waste CG to synthesize zeolite A with high whiteness. Firstly, Fe 2 O 3 component in CG is in situ reduced by C to magnetite in the process of high-temperature calcination for decarburization followed by physical magnetic separation. Secondly, the residual Fe impurity in CG is further removed by hydrothermal acid leaching. The effects of calcination temperature, calcination time, acid leaching temperature, acid concentration, and liquid to solid ratio on Fe removal rate (R Fe2O3 ) and the whiteness of the synthesized zeolite A are investigated. The influence of Fe impurities on the Ca 2+ ion exchange capacity (E) of the zeolite A synthesized from CG is clarified. R Fe2O3 could reach the value of 88.53%. The synthesized zeolite A exhibits a typical cubic morphology with rounded edges, the high whiteness of 95.46%, and the satisfactory E with the value of 296.02 mgCaCO 3 Ág À1 , both of which meet the requirements of national standard. This work suggests that this pretreatment method for CG would have broad prospects in the efficient resource utilization of CG.

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Removal of unburned carbon from fly ash using enhanced gravity separation and the comparison with froth flotation

Cited by 41 publications

References 31 publications

The Effects of Curing Temperature on CH-Based Fly Ash Composites

The Effects of Curing Temperature on CH-Based Fly Ash Composites

Investigation of the Heteroatom Doping Effect on Gasification Fine Slag Residue Carbon Oxygen Reduction Reaction Catalysts

Synthesis of zeolite A with high whiteness from coal gangue by two‐step pretreatment method

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