Figure: 2.1 Method of fly ash transfer can be dry, wet or both 5 Figure: 2.2 Coal ash generations from a pulverized coal fired boiler 6. The amount of available fly ash can be recycled, mainly by adding fly ash to cement. Fly ash in terms of particle size and mineralogical composition corresponds to mill waste.
However, there is not much literature on direct placement of fly ash as fill material. Fly ash is the best known and one of the most widely used pozzolans in the world.
OBJECTIVES
SPECIFIC OBJECTIVES
Fly ash is generally captured from the chimneys of coal-fired power plants, whereas bottom ash is removed from the bottom of the furnace. In the past, fly ash was generally released into the atmosphere, but pollution control equipment mandated in recent decades now requires it to be captured before release. Depending on the source and composition of the coal being burned, the components of the fly ash produced vary considerably, but all fly ash contains significant amounts of silicon dioxide (SiO2) (both amorphous and crystalline) and calcium oxide (CaO).
Fly ash is commonly used to supplement Portland cement in concrete production, where it can provide both technological and economic advantages, and it is increasingly used in the synthesis of geopolymers and zeolites.
CHAPTER-2
LITERATURE REVIEW GENERATION
- GENERATION OF FLY ASH
- CLASSIFICATION
- Class C fly ash
- Class F fly ash
- FEATURES
- NATURE AND COMPOSITION
- UTILIZATION
- COLLECTION .1 Ash Collection
- TRANSPORTATION .1 Fly Ash Transportation
- CHALLENGES IN HANDLING FLY ASH
- CHARECTERISTICS OF FLY ASH SLURRY
- PHYSICAL PROPERTIES
- FLY ASH MANAGEMENT
- Eliminating Waste and Abating CO2 Emissions
- Increasing pozzolanicity
- Cenospheres
- MECHANISM AND MATERIAL
In the US, fly ash is typically stored in coal-fired power plants or disposed of in landfills. The largest consumer of fly ash is only the cement industry, and some smaller quantities are used for the production of fly ash. ASTM C618 specifies two classes of fly ash: Class F fly ash and Class C fly ash.
Conditioned fly ash is also available in ash piles for landfill use and ash building products. The amount of added water is determined by the end use of the fly ash. Conditioned fly ash is widely used in aerated concrete block, grout and specialty fill applications.
The wet system of fly ash collection/disposal is the most common practice in India.
MATERIALS AND METHODS SAMPLE COLLECTION
MATERIALS AND METHODS
- SAMPLE COLLECTION
The study of the physicochemical and engineering properties of fly ash is necessary to understand the variation in the properties of fly ash in the Indian context, in order to use the same as large volume backfilling media. In addition, the research is necessary to determine properties such as permeability, particle size distribution and morphological characteristics of the fly ash that influence the settling behavior and flow properties during hydraulic transport. Fly ash is a fine, powdery material produced by burning coal to produce electricity, primarily in pulverized coal combustion boilers (PCC).
It consists mainly of non-combustible inorganic materials, but also contains some carbon left over from partially burned coal. Although fly ash particles are generally mostly spherical in shape, there are usually irregularly shaped particles also present, such as angular quartz particles. The spherical shape of fly ash results from the formation of small molten droplets as the ash travels through the boiler.
Because it is so fine, the removal and collection of fly ash from combustion gases (flue gas) requires specialized equipment such as electrostatic precipitators or fabric filters. Collection of samples of different types of ash such as fly ash, bottom ash and pond ash has different procedures. Fly ash and bottom ash are generated at the power plant and can be collected directly from the discharge points.
In most power plants, sampling pipes are provided at locations near the discharge point or near the disposal point for collecting ash samples. The sample can be collected directly in a bucket or other container and can be packaged suitable for transport. The sample was collected from the Jindal steel plant, from near the power station hopper.
SETTLING PROPERTIES
PHYSICOCHEMICAL PROPERTIES
- MOISTURE CONTENT
- TRUE DENSITY
- SPECIFIC GRAVITY
- PARTICLE SIZEDISTRIBUTION
- SEM (Scanning Electron Microscope)
The density of fly ash, which ranges from 2 to 2.8, determines the volume it will occupy for a given mass. Divide the difference between the final and initial readings by the mass of the sample to get the true density. Specific gravity is the ratio between the mass of a volume unit of soil at the specified temperature and the mass of the same volume of distilled water without gas at the specified temperature.
The specific gravity of a fly ash is used in the phase relationship between air, water and solids in a given volume of the fly ash. Fill the pycnometer with distilled (water to the mark), clean the outside surface of the pycnometer with a clean, dry cloth. The particle size of the fly ash was measured using a laser-based particle size analyzer, namely a Mastersizer 2000 from Malvern Instruments Ltd.
The BET theory is a rule for the physical adsorption of gas molecules on a solid surface and serves as the basis for an important analytical technique for measuring the specific surface area of a material. The value of the slope A and the y-intercept I of the line are used to calculate the amount of gas adsorbed by a monolayer vm and the BET constant c. This monolayer capacity can be calculated from the adsorption isotherm by means of the BET equation.
In the case of a very small surface area (below 1 m2/g), the sensitivity of instruments using nitrogen is insufficient and krypton at 77.3 K must be used. The adsorption isotherm is the graph of the amount of gas adsorbed (in mol/g) as a function of the relative pressure p/p0. The signals result from interactions of the electron beam with atoms at or near the surface of the sample.
Because the intensity of the BSE signal is strongly related to the atomic number (Z) of the sample, BSE images can provide information about the distribution of different elements in the sample. With the attachment of the energy dispersive spectrometer (EDS) or wavelength dispersive spectrometer (WDS), the precise elemental composition of material can be obtained with high spatial resolution.
SLUMP TEST (ASTM Method C143 CAN3-A23.2-M77)
Immediately remove the mold from the fly shaft by carefully lifting it in a vertical direction without lateral or torsional movement. Measure the difference between the height of the mold and the height of the sample at its highest point to the nearest 6.3 mm.
CHAPTER-4
RESULT AND DISCUSSION CONCLUSION
RESULTS & DISCUSSION
- SEM (Scanning Electron Microscope)
- SPECIFIC GRAVITY (ASTM D 854)
- TRUE DENSITY
- MOISTURE CONTENT
- PARTICLE SIZE ANALYSIS
- SETTLING CHARACTERISTICS OF FLY ASH Fly ash: 40 gm and water: 60ml
- SLUMP TEST
The fly ash samples consisted mainly of amorphous aluminosilicate spheres with a smaller number of iron-rich spheres. Despite the inherent variability of fly ash samples, this analysis indicated that the primary mineral/morphological structures are quite common. The specific gravity of the fly ash collected from Jindal Steel Plant was found to be 2.275.
The true density of fly ash collected at Jindal Steel plant was found to be 2.29. The moisture content of fly ash collected at Jindal Steel Plant was found to be 0.175%. The specific BET surface area of fly ash collected from Zindal steel plant was found to be 0.44 square meters per gram.
The size ranges of the fly ash particles indicate that the composite produced can be considered dispersion-reinforced as well as particle-reinforced composite. The total time taken to settle fly ash in the mixtures was 2 hours 47 minutes at the reading of 45 ml of the mixtures in the flask. The total time it took for fly ash to settle in the mixtures was 3 hours and 15 minutes at the reading of 55 ml of mixtures in the flask.
The total time taken to settle fly ash in the mixtures was found to be 2 hours 40 minutes at the reading of 39 ml of the mixtures in the flask. The total time taken to settle the fly ash into the mixture was 1 hour and 50 minutes at the reading of 31 ml of mixtures in the flask. The slump height of the fly ash collected from Jindal Steel Plant was found to be 80 mm.
CONCLUSION
From the above figure, it was found that the composition of fly ash: 25 g and water: 75 ml was the better parameter among the other parameters for solid-liquid separation in slurries during the filling activity. Due to the fine-grained nature of the solid components, the fly ash slurries exhibit remarkable sluggishness in settling and also do not provide clear above solutions. The composition of fly ash: 25 g and water: 75 ml is the good parameter for solid-liquid separation in slurries during the filling activity.
Class F fly ash is therefore the weaker in pozzolanic dust because a very small amount of calcium oxide is present. The chemical, physical and mineralogical properties of fly ash significantly affected the performance of fly ash in filling low-lying and mineless areas. Bituminous (pozzolanic) fly ash is more commonly used for the construction of embankments and structural fills than sub-bituminous or lignite (self-cementing) fly ash.
This is partly due to the self-cementing properties of the latter type, which hardens almost immediately after the addition of water.
“Studies on the maximum settled concentration, mixing and rheological properties of high concentration fly ash-bottom ash mixture slurry”, Proc. of the International Conference on Fly Ash Utilization, New Delhi, pp. 2000): “Characteristics of coal ash and their role in hydraulic design of ash discharge pipelines”, Indian Journal of Engineering and Material Science, Vol.7, pp Effect of Particle Size Distribution on Rheological Properties of Fly Ash Slurry at High Concentrations”, Intl. Managing Coal Combustion Residues in Mines, Committee on Mine Placement of Coal Combustion Wastes, National Research Council of the National Academies, 2006. ASTM C618 - 08 Standard Specifications for Coal Fly Ash and Raw or Calcined Natural Pozzolana for Use in Concrete". http://www .astm.org/cgi-bin/SoftCart.exe/DATABASE.CART/REDLINE_PAGES/C618.htm?L+mystore+lsft A New Era in Control Density Fill", Proceedings of the Tenth International Ash Utilization Symposium.
Dhadse, s, Kumari, P, Bhagia, LJ, Fly Ash Characterization, Utilization and Government Initiatives in India - A Review Vol.67, January 2008, pp. C, 2008, Characterization of fly ash from different locations of electrostatic precipitators, The 12th International Conference of the International Association for Computational Methods and Advances in Geomechanics (IACMAG) October 1-6, 2008.