Analysis of Construction Material Using SEM (Scanning Electron Microscope)

2013 ◽  
Vol 677 ◽  
pp. 145-148
Author(s):  
Hai Ying Zhang ◽  
Chuan Yun Wan
Keyword(s):  
Heavy Metals ◽  
Fly Ash ◽  
Pollution Control ◽  
Room Temperature ◽  
Construction Material ◽  
Material Structure ◽  
Heating Process ◽  
Air Pollution Control ◽  
Change Of Microstructure ◽  
Electronic Microscope

This study analyzed change of microstructure of air pollution control (APC) ash after being sintered at 700°C, 900°C and 1100°C using SEM (scanning electronic microscope). It was found that fly ash has a loose structure and lots of pores among the particulates, making it easy for heavy metals to be extracted into the environment. Lots of glass phases exist in it, which improves activity of the ash using as a construction material. Structure of fly ash is strengthened with increase of temperature, which is conducive to stabilization of heavy metals. Crystal content increases from room temperature to 900°C and then decreases in the heating process, while content of glass phases has a reverse trend.

Analysis of the Ash from One Shanghai Plant Using XRD (X-Ray Diffraction)

2013 ◽  
Vol 664 ◽  
pp. 232-235
Author(s):  
Guo Xian Ma ◽  
Hai Ying Zhang
Keyword(s):  
Fly Ash ◽  
Pollution Control ◽  
Room Temperature ◽  
Thermal Characterization ◽  
Xrd Analysis ◽  
Air Pollution Control ◽  
X Ray Diffraction ◽  
X Ray ◽  
Calcium Silicates

This study aims to develop a methodology for thermal characterization of APC (air pollution control)fly ash using XRD (X-ray diffraction). It performed XRD analysis as a function of temperature between room temperature and 1200 °C. It is found that major mineralogical components of fly ash involve SiO2, CaCl2, Ca3Si2O7, Ca2SiO4–0.35H2O, Ca9Si6O21–H2O, K2Al2Si2O8–3.8H2O and AlCl3–4Al(OH)3–4H2O. Glass phases account for around 57%, which is conducive to reduction of energy in recycling of the ash. Salts decompose firstly with increase of temperature and then oxides derived from the decomposition process react with SiO2, forming silicates, calcium-silicates and aluminosilicates.

Thermally induced transformations of Fe oxide-stabilized residues from waste incineration

2001 ◽  
Vol 65 (5) ◽  
pp. 635-643 ◽  
Author(s):  
M. A. Sørensen ◽  
C. Bender Koch
Keyword(s):  
Heavy Metals ◽  
Room Temperature ◽  
Waste Incineration ◽  
Oxide Phase ◽  
Waste Incinerator ◽  
Air Pollution Control ◽  
Fe Oxide ◽  
Thermally Induced ◽  
Co Precipitation ◽  
Reducing Gases

AbstractAir pollution control (APC) facilities at waste incinerator plants produce large quantities of solid residues rich in salts and heavy metals. Heavy metals are readily released to water from the residues and it has, therefore, been found suitable to apply a rapid co-precipitation/adsorption process as a means to immobilize the toxic elements. In the ‘Ferrox process’, this immobilization is based on co-precipitation with an Fe(III) oxide formed by oxidation of Fe(II) by air in an aqueous slurry with the APC residue at alkaline pH. In this work we have undertaken a Mössbauer spectroscopy study of the Fe oxide phase formed by precipitation at room temperature and of the oxides present after heating to 600 and 900°C. The only Fe oxide observed in the Ferrox product at room temperature is a very poorly crystalline ferrihydrite. Analytical transmission electron microscopy showed that the main elements associated with the ferrihydrite are Si and Ca. Following heating to 600°C the oxide is still characterized as an amorphous Fe oxide, and it is probable that Si associated with the ferrihydrite is decisive in preventing crystallization. After the 900°C treatment a transformation into defect maghemite is observed. Reducing gases produced from carbon in the samples probably induces this transformation. It eases, thus, the reduction of Fe(III) and the consequent formation of magnetite that eventually oxidizes to maghemite during cooling in air.

scholarly journals Acoustic Agglomeration of Power Plant Fly Ash for Environmental and Hot Gas Clean-up

1988 ◽  
Vol 110 (4) ◽  
pp. 552-557 ◽  
Author(s):  
G. Reethof
Keyword(s):  
Fly Ash ◽  
Power Plant ◽  
Pollution Control ◽  
Flue Gases ◽  
Analytical Models ◽  
Particle Removal ◽  
Air Pollution Control ◽  
Hot Gas ◽  
History Of ◽  
Viable Method

Acoustic agglomeration of power plant fly ash is an intermediate treatment of the flue gases to increase the size of the small micron (1–5) and submicron (0.1–1) particulates to large micron sizes (5–10) so that the conventional particle removal devices such as bag houses, electrostatic precipitators, and scrubbers can operate more efficiently. This paper provides a brief history of the topic, introduces some of the fundamental issues and gives some recent results of analytical models of the processes. The experimental facility is briefly described and some analytical results are shown which compare well with the experimental results. Most important of all, the paper shows that acoustic agglomeration is a technically and potentially economically viable method to improve air pollution control.

Chlorine Sources, Sinks, and Impacts in WTE Power Plants

2010 ◽  
Author(s):  
Nickolas J. Themelis
Keyword(s):  
Air Pollution ◽  
Fly Ash ◽  
Corrosion Rate ◽  
Polyvinyl Chloride ◽  
Pollution Control ◽  
Power Plants ◽  
Air Pollution Control ◽  
Combustion Gases ◽  
The U.S ◽  
Stack Gas

The principal sources of chlorine in the MSW feed to WTE power plants are food wastes (e.g., wheat, green vegetables, melon, pineapple), yard wastes (leaves, grass, etc.), salt (NaCl), and chlorinated plastics (mostly polyvinyl chloride). Chlorine has important impacts on the WTE operation in terms of higher corrosion rate than in coal-fired power plants, formation of hydrochloric gas that must be controlled in the stack gas to less than the U.S. EPA standard (29 ppm by volume), and potential for formation of dioxins and furans. Past Columbia studies have shown that the chlorine content in MSW is in the order of 0.5%. In comparison, chlorine concentration in coal is about 0.1%; this results in much lower HCl concentration in the combustion gases and allows coal-fired power plants to be operated at higher superheater tube temperatures and thus higher thermal efficiencies. Most of the chlorine output from a WTE is in the fly ash collected in the fabric filter baghouse of the Air Pollution Control system. This study examined in detail the sources and sinks of chlorine in a WTE unit. It is concluded that on the average MSW contains about 0.5% chlorine, which results in hydrogen chloride concentration in the WTE combustion gases of up to 600 parts per million by volume. About 45% of the chlorine content in MSW derives from chlorinated plastics, mainly polyvinyl chloride (PVC), and 55% from salt (NaCl) and chlorine-containing food and yard wastes. An estimated 97–98% of the chlorine input is converted to calcium chloride in the dry scrubber of the Air Pollution Control (APC) system and captured in the fly ash collected in the baghouse; the remainder is in the stack gas at a concentration that is one half of the U.S. EPA standard. Reducing the input of PVC in the MSW stream would have no effect on dioxin formation but would reduce the corrosion rate in the WTE boiler.

Extraction of Heavy Metals from the Ash Using Hydrochloric Acid

2013 ◽  
Vol 811 ◽  
pp. 277-279 ◽  
Author(s):  
Guo Xian Ma ◽  
Hai Ying Zhang
Keyword(s):  
Heavy Metals ◽  
Air Pollution ◽  
Hydrochloric Acid ◽  
Acid Concentration ◽  
Pollution Control ◽  
Acid Extraction ◽  
Hydrochloric Acid Concentration ◽  
Air Pollution Control ◽  
Removal Ratio

This study aims to develop a methodology for analysis of extraction of heavy metals from air pollution control (APC) ash using hydrochloric acid. In this work, the ash was firstly characterized and then hydrochloric acid was used to extract Ni, Zn, Pb and Cu out from the ash. In addition, influence of hydrochloric acid concentration on removal ratio of the four heavy metals was studied. It was found that removal ratio followed the decreasing sequence of Pb > Zn > Cd > Cu for acid extraction using hydrochloric acid. The optimal acid concentration was 4 mol/L, which resulted in a removal ratio of 91% for Pb, 84% for Zn, around 53% for Cd and around 41% for Cu.

Organic Complex Chelators for Stabilization of Heavy Metals in Fly Ash

2013 ◽  
Vol 864-867 ◽  
pp. 217-220
Author(s):  
Jin Bo Wang ◽  
Rui Xiang Qin
Keyword(s):  
Heavy Metals ◽  
Fly Ash ◽  
Municipal Solid Waste ◽  
Pollution Control ◽  
Ph Value ◽  
Acidic Environment ◽  
Organic Complex ◽  
Waste Landfill ◽  
Optimized Conditions ◽  
Strong Ability

The organic complex chelators (OCC) were synthesized and applied to stabilization of heavy metals in fly ash according to the municipal solid waste landfill pollution control standard. The influences of different chelators, amount of chelator, pH value of leaching, solidification time were investigated and optimized. Comparing to the traditional inorganic chelator, this OCC has more powerful performance of stabilization. Under the optimized conditions, the leaching concentrations for typical heavy metals Pb and Cd were less than 0.19 and 0.11 mg/L, respectively, which could meet the demand of landfill. The organic complex chelators could react with heavy metals to form stable complexes, which would be embedded in fly ash particles and have the strong ability to prohibit leaching from acidic environment.

Analysis of the Cement-Stabilized Ash by XRD (X-Ray Diffraction)

2013 ◽  
Vol 811 ◽  
pp. 240-243
Author(s):  
Guo Xian Ma ◽  
Hai Ying Zhang
Keyword(s):  
Fly Ash ◽  
Pollution Control ◽  
Xrd Analysis ◽  
Air Pollution Control ◽  
Hydration Products ◽  
X Ray Diffraction ◽  
X Ray ◽  
Time Period ◽  
Incineration Process ◽  
Mineralogical Compositions

APC (air pollution control) fly ash, generated in incineration process of municipal solid waste, is regarded as a hazardous waste because of enrichment of heavy metals. In this work, stabilization of the ash with cement was studied. In addition, XRD analysis of the cement stabilized body was performed as a function of conservation time period. It was It was found that the hydration products cement fly ash and other particles together, which rises with increase of the cement / ash ratio and duration of conservation. Major mineralogical compositions CaCO3, Ca (0H)2 and C-H-S hydration products. Content of Ca (0H)2 and C-H-S rises with increase of conservation period and cement / ash ratio.

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