Experimental study on the washing characteristics of fly ash from municipal solid waste incineration

The disposal of fly ash with high salt content has become an important bottleneck for the further application of municipal solid waste incineration (MSWI). In this study, the soluble salt content and composition of fly ash from different MSWI were analysed. The composition of fly ash was affected by incinerator type and flue gas cleaning system, especially the type of deacidification solvent. The soluble salt content in fly ash from MSW grate incinerator can be over 35.16%. Most of the soluble salt was calcium salt and chloride salt. The effect of washing parameters including liquid/solid (L/S) ratio and washing time on salt removal from fly ash were studied. Raw fly ash contained high chlorine (Cl) with the maximum of 19.83% and it can be significantly reduced by washing. Double-washing and secondary-washing had better performance than single-washing on salt removal. The secondary-washing did not only save water, but also reduced the energy cost during evaporation for crystallising soluble salt. Based on the analysis of variance (ANOVA), L/S ratio was the most principal factor for salt and Cl removal of fly ash by washing.

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Microstructure and Strength of Alkali-Activated Bricks Containing Municipal Solid Waste Incineration (MSWI) Fly Ash Developed as Construction Materials

Sustainability ◽

10.3390/su11051283 ◽

2019 ◽

Vol 11 (5) ◽

pp. 1283 ◽

Cited By ~ 5

Author(s):

Peng Xu ◽

Qingliang Zhao ◽

Wei Qiu ◽

Yan Xue ◽

Na Li

Keyword(s):

Compressive Strength ◽

Fly Ash ◽

Municipal Solid Waste ◽

Solid Waste ◽

Building Materials ◽

Waste Incineration ◽

Engineering Properties ◽

Chloride Salt ◽

Municipal Solid Waste Incineration ◽

Alkali Activated

Alkali-activated materials (AAM) are widely applied in the field of building materials and civil engineering to substitute cement materials. This study used two types of municipal solid waste incineration fly ash (MSWI-FA): grate-firing fly ash (GFFA) and fluidized bed fly ash (FBFA) as brick raw materials. Various weight ratio of 20%, 30%, and 40% GFFA and FBFA were added to coal fly ash (CFA), GGBFs (Ground Granulated Blast-Furnace Slag), and an alkali-activating reagent to produce alkali-activated bricks. Microstructure and crystalline phase composition were observed to analyze their compressive strength, and a leaching test was used to prove the material’s safety for the environment. It can be seen from the results of this study that the alkali-activated bricks containing FBFA had higher compressive strength than those containing GFFA in the same amount. Considering the engineering properties, the alkali-activated bricks containing FBFA are more suitable to be used as building materials. The difference in the compressive strength resulted from the large amount of calcium compounds and chloride salts present in the GFFA. From SEM analysis, it was observed that there was a large number of pores in the microstructure. It was also found from the results of XRD that the bricks containing GFFA contained a large amount of chloride salt. From the results of the two leaching tests, it was found that the amounts of six heavy metals detected in the leachates of the bricks in this study met the corresponding regulation standards. This described MSWI-FA is suitable for use as alkali-activated material, and its products have potential to be commercially used in the future.

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A mini-review of heavy metal recycling technologies for municipal solid waste incineration fly ash

Waste Management & Research ◽

10.1177/0734242x211003968 ◽

2021 ◽

pp. 0734242X2110039

Author(s):

Huan Wang ◽

Fenfen Zhu ◽

Xiaoyan Liu ◽

Meiling Han ◽

Rongyan Zhang

Keyword(s):

Fly Ash ◽

Municipal Solid Waste ◽

Solid Waste ◽

Waste Incineration ◽

Electrochemical Process ◽

Chemical Extraction ◽

Air Pollution Control ◽

Municipal Solid Waste Incineration ◽

Mswi Fly Ash ◽

Metal Recycling

This mini-review article summarizes the available technologies for the recycling of heavy metals (HMs) in municipal solid waste incineration (MSWI) fly ash (FA). Recovery technologies included thermal separation (TS), chemical extraction (CE), bioleaching, and electrochemical processes. The reaction conditions of various methods, the efficiency of recovering HMs from MSWI FA and the difficulties and solutions in the process of technical development were studied. Evaluation of each process has also been done to determine the best HM recycling method and future challenges. Results showed that while bioleaching had minimal environmental impact, the process was time-consuming. TS and CE were the most mature technologies, but the former process was not cost-effective. Overall, it has the greatest economic potential to recover metals by CE with scrubber liquid produced by a wet air pollution control system. An electrochemical process or solvent extraction could then be applied to recover HMs from the enriched leachate. Ongoing development of TS and bioleaching technologies could reduce the treatment cost or time.

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An Experimental Study on the Melting Solidification of Municipal Solid Waste Incineration Fly Ash

Sustainability ◽

10.3390/su13020535 ◽

2021 ◽

Vol 13 (2) ◽

pp. 535

Author(s):

Jing Gao ◽

Tao Wang ◽

Jie Zhao ◽

Xiaoying Hu ◽

Changqing Dong

Keyword(s):

Heavy Metals ◽

High Temperature ◽

Fly Ash ◽

Municipal Solid Waste ◽

Solid Waste ◽

Liquid Slag ◽

Melting Process ◽

Waste Incineration ◽

Municipal Solid Waste Incineration ◽

Mswi Fly Ash

Melting solidification experiments of municipal solid waste incineration (MSWI) fly ash were carried out in a high-temperature tube furnace device. An ash fusion temperature (AFT) test, atomic absorption spectroscopy (AAS), scanning electron microscope (SEM), and X-ray diffraction (XRD) were applied in order to gain insight into the ash fusibility, the transformation during the melting process, and the leaching behavior of heavy metals in slag. The results showed that oxide minerals transformed into gehlenite as temperature increased. When the temperature increased to 1300 °C, 89 °C higher than the flow temperature (FT), all of the crystals transformed into molten slag. When the heating temperatures were higher than the FT, the volatilization of the Pb, Cd, Zn, and Cu decreased, which may have been influenced by the formation of liquid slag. In addition, the formation of liquid slag at a high temperature also improved the stability of heavy metals in heated slag.

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