scholarly journals Optimization of Metal Recovery from MSWI Fly Ash by Acid Leaching: Findings from Laboratory- and Industrial-Scale Experiments

Processes ◽  
2021 ◽  
Vol 9 (2) ◽  
pp. 352
Author(s):  
Gisela Weibel ◽  
Anna Zappatini ◽  
Mirjam Wolffers ◽  
Stefan Ringmann
Keyword(s):  
Heavy Metals ◽  
Fly Ash ◽  
Acid Leaching ◽  
Waste Incineration ◽  
Metal Recovery ◽  
Industrial Scale ◽  
Mswi Fly Ash ◽  
Gas Cleaning ◽  
Leaching Process

A major part of Swiss fly ashes (FA) from municipal solid waste incineration (MSWI) are treated with the acid fly ash leaching process (FLUWA) in order to recover heavy metals prior to deposition. The FLUWA process uses scrub water from wet flue gas cleaning to leach heavy metals from FA. The leaching efficiency is strongly dependent on the leaching conditions (e.g., pH, Eh, L/S-ratio). This case study presents the optimization of the FLUWA process at the MSWI plant Linth, Switzerland, through determination of ideal process parameters for optimal metal recovery. By means of laboratory- and industrial-scale experiments, the process was adjusted towards a more efficient leaching of Zn, Pb, Cu, and Cd. This included the use of an oxidizing agent (hydrogen peroxide). Laboratory experiments proved to be a powerful tool for simulating process optimizations at industrial scale. An ideal leaching pH of 3.8 was determined and it was observed that the process stability is significantly influenced by the L/S-ratio applied to the leaching process. In the course of the study, the recovery could be improved to 67% Zn, 66% Pb, 30% Cu, and 91% Cd. It can be concluded that for optimal metal recovery the process has to be individually adjusted to the composition of the processed FA and scrub water of each specific FLUWA process.

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

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.

scholarly journals Inventory of MSWI Fly Ash in Switzerland: Heavy Metal Recovery Potential and Their Properties for Acid Leaching

Processes ◽  
2020 ◽  
Vol 8 (12) ◽  
pp. 1668
Author(s):  
Wolfgang Zucha ◽  
Gisela Weibel ◽  
Mirjam Wolffers ◽  
Urs Eggenberger
Keyword(s):  
Heavy Metals ◽  
Fly Ash ◽  
Acid Leaching ◽  
Acid Neutralizing Capacity ◽  
Mswi Fly Ash ◽  
Mineralogical Characterization ◽  
Recovery Rates ◽  
Leaching Potential ◽  
Geochemical Properties ◽  
Neutralizing Capacity

From the year 2021 on, heavy metals from Swiss municipal solid waste incineration (MSWI) fly ash (FA) must be recovered before landfilling. This is predominantly performed by acid leaching. As a basis for the development of defined recovery rates and for the implementation of the recovery process, the authorities and plant operators need information on the geochemical properties of FA. This study provides extended chemical and mineralogical characterization of all FA produced in 29 MSWI plants in Switzerland. Acid neutralizing capacity (ANC) and metallic aluminum (Al0) were additionally analyzed to estimate the effort for acid leaching. Results show that all FA samples are composed of similar constituents, but their content varies due to differences in waste input and incineration conditions. Based on their geochemical properties, the ashes could be divided into four types describing the leachability: very good (6 FA), good (10 FA), moderate (5 FA), and poor leaching potential (8 FA). Due to the large differences it is suggested that the required recovery rates are adjusted to the leaching potential. The quantity of heavy metals recoverable by acid leaching was estimated to be 2420 t/y Zn, 530 t/y Pb, 66 t/y Cu and 22 t/y Cd.

Leaching of Heavy Metals from Municipal Solid Waste Incineration (MSWI) Fly Ash Using Nitric Acid

2012 ◽  
Vol 249-250 ◽  
pp. 918-921 ◽  
Author(s):  
Hai Ying Zhang ◽  
Guo Xian Ma
Keyword(s):  
Heavy Metals ◽  
Fly Ash ◽  
Nitric Acid ◽  
Municipal Solid Waste ◽  
Waste Incineration ◽  
Acid Extraction ◽  
Municipal Solid Waste Incineration ◽  
Mswi Fly Ash ◽  
Removal Ratio ◽  
Solid Ratio

The presence of heavy metals in municipal solid waste incineration (MSWI) fly ash is of environmental concern due to their leaching potential in landfill environments. Acid extraction is a conventional method of safe treatment of fly ash. In this work, nitric acid was used as the extraction acid to leach Ni, Zn, Pb and Cu out from the ash. In addition, influence of nitric acid concentration and liquid to solid ratio on removal ratio of the four heavy metals was studied. It was found that removal ratio followed the decreasing sequence of Pb > Cd > Cu > Zn for acid extraction using nitric acid. The optimal extraction condition was 5.3 mol/L of nitric concentration at 20 liquid to solid ratio, which resulted in a removal ratio of 98% for Pb, 86% for Cd, around 73% for Cu and around 42% for Zn.

Analysis of Heavy Metal Leaching in Fly Ash from One Shanghai Municipal Solid Waste Incineration (MSWI) Plant

2012 ◽  
Vol 531 ◽  
pp. 292-295
Author(s):  
Hai Ying Zhang ◽  
Guo Liang Yuan ◽  
Guo Xian Ma
Keyword(s):  
Heavy Metals ◽  
Fly Ash ◽  
Municipal Solid Waste ◽  
Solid Waste ◽  
Hazardous Waste ◽  
Extraction Procedure ◽  
Waste Incineration ◽  
Municipal Solid Waste Incineration ◽  
Mswi Fly Ash ◽  
Leaching Toxicity

The characteristics and leaching behavior of heavy metals in fly ash, sampled from one MSWI (municipal solid waste incineration) plant in Shanghai China, were investigated. The results indicated that the main elements of fly ash were Fe, K, Na, Cl, Si, Ca, Al, and the total fraction of heavy metals was in the range of 0.8 % - 2.0%. Hence, MSWI fly ash was considered to be one kind of hazardous waste due to its potential environmental risk. Leaching toxicity was performed on fly ash samples from the MSWI plant in Shanghai China. Leaching toxicity of the heavy metals by the ALT (available leaching toxicity) procedure exceeded that by the HVEP (horizontal vibration extraction procedure) standard. Leaching concentrations of Ni, Zn, Cd and Pb exceeded the limit of hazardous waste identification standard. Hence, fly ash is a hazardous waste.

H2S adsorption by municipal solid waste incineration (MSWI) fly ash with heavy metals immobilization

Chemosphere ◽  
2018 ◽  
Vol 195 ◽  
pp. 40-47 ◽  
Author(s):  
Huanan Wu ◽  
Yu Zhu ◽  
Songwei Bian ◽  
Jae Hac Ko ◽  
Sam Fong Yau Li ◽  
...  
Keyword(s):  
Heavy Metals ◽  
Fly Ash ◽  
Municipal Solid Waste ◽  
Solid Waste ◽  
Waste Incineration ◽  
Municipal Solid Waste Incineration ◽  
Mswi Fly Ash ◽  
H2s Adsorption

Leaching of Heavy Metals from Municipal Solid Waste Incineration (MSWI) Fly Ash Using Sulfuric Acid

2012 ◽  
Vol 249-250 ◽  
pp. 922-926 ◽  
Author(s):  
Hai Ying Zhang ◽  
Guo Xian Ma
Keyword(s):  
Heavy Metals ◽  
Sulfuric Acid ◽  
Fly Ash ◽  
Nitric Acid ◽  
Municipal Solid Waste ◽  
Solid Waste ◽  
Waste Incineration ◽  
Acid Extraction ◽  
Municipal Solid Waste Incineration ◽  
Mswi Fly Ash

Municipal solid waste incineration (MSWI) fly ash, a must by-product in incineration of municipal solid waste (MSW) combustion is of environmental concern due to its enrichment in heavy metals (Ni, Cd, Cu and Pb). Extraction using sulfuric acid is a conventional method of safe treatment of fly ash. In this work, influence of sulfuric acid concentration and liquid to solid ratio on removal efficiency of the four heavy metals was investigated. It was found that Removal ratio followed the decreasing sequence of Cd > Cu > Pb >Zn for acid extraction using sulfuric acid, quite different with that sequence of Pb > Cd > Cu > Zn for extraction using nitric acid. Sulfuric acid was efficient in removing Cd and Cu, but less efficient in removing Ni and Zn. Compared with nitric acid, sulfuric acid was less effective in removing Pb, Cu and Ni.

Washing of the Ash from One Shanghai Plant Using Phosphoric Acid

2013 ◽  
Vol 664 ◽  
pp. 228-231 ◽  
Author(s):  
Guo Xian Ma ◽  
Hai Ying Zhang
Keyword(s):  
Heavy Metals ◽  
Sulfuric Acid ◽  
Fly Ash ◽  
Phosphoric Acid ◽  
Waste Incineration ◽  
Acid Extraction ◽  
Mswi Fly Ash ◽  
Solid Ratio ◽  
Cd Removal ◽  
Phosphoric Acid Concentration

Municipal solid waste incineration (MSWI) fly ash was regarded as one kind of hazardous waste due to the enrichment of heavy metals (Zn, Pb, Cd and Cu), which should be removed from the ash or stabilized prior to final landfill disposal. Extraction with phosphoric acid is a conventional method of safe treatment of fly ash. In this work, influence of phosphoric acid concentration and liquid to solid ratio on removal efficiency of the four heavy metals was investigated. It was found that phosphoric acid was efficient in removing Pb, Zn and Cu but less efficient in removing Cd. Removal ratio followed the decreasing sequence of Pb >Zn > Cd > Cu for acid extraction using phosphoric acid, quite different with that for sulfuric acid. In comparison with sulfuric acid, phosphoric acid was more effective in removing the four heavy metals.

Chemical Extraction of Heavy Metals from the Ash Using Perchloric Acid

2013 ◽  
Vol 459 ◽  
pp. 3-6
Author(s):  
Hai Ying Zhang ◽  
Shu Zhen Li
Keyword(s):  
Heavy Metals ◽  
Fly Ash ◽  
Perchloric Acid ◽  
Waste Incineration ◽  
Major Elements ◽  
Chemical Extraction ◽  
Acid Extraction ◽  
Municipal Solid Waste Incineration ◽  
Mswi Fly Ash ◽  
Solid Ratio

Elementary compositions of municipal solid waste incineration (MSWI) fly ash was analyzed. In addition, influence of perchloric acid concentration and liquid to solid ratio on removal efficiency of the four heavy metals was investigated. It was found that there are 11 major elements in fly ash, with content over 1%, and content of them follows sequence of O > Ca > Si > Cl > Al > Fe > Na > S > C > Mg. These major elements account for around 97.5~98.7% of the ash. Removal ratio of Zn, Pb, Cd and Cu followed the decreasing sequence of Zn > Pb > Cd >Cu for acid extraction using perchloric acid. The optimal extraction conditions are: perchloric acid 3 M, liquid to solid ratio 30 mL liquid / 1 g ash, resulting in an extraction ratio of 89% for Zn, 85% for Pb, 41% for Cd and 32% for Cu.

Immobilization of MSWI Fly Ash with Geopolymers

2010 ◽  
Vol 150-151 ◽  
pp. 1564-1569 ◽  
Author(s):  
Man Tong Jin ◽  
Cai Ju Huang ◽  
Liang Chen ◽  
Xin Sun ◽  
Lian Jun Wang
Keyword(s):  
Heavy Metals ◽  
Compressive Strength ◽  
Fly Ash ◽  
Sodium Silicate Solution ◽  
Waste Incineration ◽  
Silicate Solution ◽  
Hazardous Wastes ◽  
Municipal Solid Waste Incineration ◽  
Mswi Fly Ash ◽  
Solidified Body

The geopolymer was chosen to immobilize the municipal solid waste incineration (MSWI) fly ash because of its strong fixing capacity for heavy metals. The fly ash-based geopolymer was synthesized from metakaolinite with MSWI fly ash under activation of sodium silicate solution, and then cured at relative humidity (RH) between 40% and 90% at 20°C. The ability of immobilization of heavy metals in MSWI fly ash with the geopolymer was evaluated in terms of the compressive strength and leaching concentration. The experimental results confirmed that the compressive strength of the resulting solidified body could achieve 35.13 MPa after 7 days of curing. Meanwhile, the leaching concentrations of Pb, Zn, Cu and Cr were 0.0230 mg/kg, 0.186 mg/kg, 0.231 mg/kg, and 6.56 mg/kg, respectively. We confirm that geopolymerisation is an effective alternative in the disposal of various hazardous wastes containing heavy metals.

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