Abstract: Many concrete technologists are looking for a solution to replace Fly Ashes that would be unavailable in a few years as an element that occurs as a major component of many types of concrete. The importance of such component is clear - it saves cement and reduces the amount of CO2 in the atmosphere that occurs during cement production. Wood Ashes from electrostatic filter can be used as a valuable substitute in concrete. The laboratory investigations showed that the wood ash concrete had a compressive strength comparable to coal fly ash concrete. These results indicate that wood ash can be used to manufacture normal concrete.
Abstract: Coal fly ash, an industrial by product of coal
combustion thermal power plants is considered as a hazardous
material and its improper disposal has become an environmental
issue. On the other hand, manufacturing conventional clay bricks
involves on consumption of large amount of clay and leads
substantial depletion of topsoil. This paper unveils the possibility of
using fly ash as a partial replacement of clay for brick manufacturing
considering the local technology practiced in Bangladesh. The effect
of fly ash with different replacing ratio (0%, 20%, 30%, 40%, and
50% by volume) of clay on properties of bricks was studied. Bricks
were made in the field parallel to ordinary bricks marked with
specific number for different percentage to identify them at time of
testing. No physical distortion is observed in fly ash brick after
burning in the kiln. Results from laboratory test show that
compressive strength of brick is decreased with the increase of fly
ash and maximum compressive strength is found to be 19.6 MPa at
20% of fly ash. In addition, water absorption of fly ash brick is
increased with the increase of fly ash. The abrasion value and
Specific gravity of coarse aggregate prepared from brick with fly ash
also studied and the results of this study suggests that 20% fly ash
can be considered as the optimum fly ash content for producing good
quality bricks utilizing present practiced technology.
Abstract: Coal fly ash is formed as a solid waste product from
the combustion of coal in coal fired power stations. Huge amounts of
fly ash are produced globally every year and are predicted to
increase. Nowadays, less than half of the fly ash is used as a raw
material for cement manufacturing, construction and the rest of it is
disposed as a waste causing yet another environmental concern. For
this reason, the recycling of this kind of slurries into useful materials
is quite important in terms of economical and environmental aspects.
The purpose of this study is to evaluate the Orhaneli and
Tuncbilek coal fly ashes for utilization in some industrial
applications. Therefore the mineralogical and chemical compositions
of these fly ashes were analyzed by X-ray fluorescence spectroscopy,
ourier-transform infrared spectrometer, and X-ray diffraction. The
silicon (Si) and aluminum (Al) in the fly ashes were activated by
alkali fusion technique with sodium hydroxide. The obtained extracts
were analyzed for Si and Al content by inductively coupled plasma
optical emission spectrometry.
Abstract: Coal fly ash (CFA) generated by coal-based thermal
power plants is mainly composed of some oxides having high
crystallinity, like quartz and mullite. In this study, the effect of CFA
crystallinity toward lead adsorption capacity was investigated. To get
solid with various crystallinity, the solution of sodium hydroxide
(NaOH) of 1-7 M was used to treat CFA at various temperature and
reflux time. Furthermore, to evaluate the effect of NaOH-treated CFA
with respect to adsorption capacity, the treated CFA were examine as
adsorbent for removing lead in the solution. The result shows that
using NaOH to treat CFA causes crystallinity of quartz and mullite
decrease. At higher NaOH concentration (>3M), in addition the
damage of quartz and mullite crystallinity is followed by crystal
formation called hydroxysodalite. The lower crystalllinity, the higher
adsorption capacity.
Abstract: Batch adsorption of recalcitrant melanoidin using the abundantly available coal fly ash was carried out. It had low specific surface area (SBET) of 1.7287 m2/g and pore volume of 0.002245 cm3/g while qualitative evaluation of the predominant phases in it was done by XRD analysis. Colour removal efficiency was found to be dependent on various factors studied. Maximum colour removal was achieved around pH 6, whereas increasing sorbent mass from 10g/L to 200 g/L enhanced colour reduction from 25% to 86% at 298 K. Spontaneity of the process was suggested by negative Gibbs free energy while positive values for enthalpy change showed endothermic nature of the process. Non-linear optimization of error functions resulted in Freundlich and Redlich-Peterson isotherms describing sorption equilibrium data best. The coal fly ash had maximum sorption capacity of 53 mg/g and could thus be used as a low cost adsorbent in melanoidin removal.
Abstract: Coal fly ash (CFA) generated by coal-based thermal
power plants is mainly composed of quartz, mullite, and unburned
carbon. In this study, the effect of unburned carbon on CFA toward
its adsorption capacity was investigated. CFA with various carbon
content was obtained by refluxing it with sulfuric acid having various
concentration at various temperature and reflux time, by heating at
400-800°C, and by sieving into 100-mesh in particle size. To
evaluate the effect of unburned carbon on CFA toward its adsorption
capacity, adsorption of methyl violet solution with treated CFA was
carried out. The research shows that unburned carbon leads to
adsorption capacity decrease. The highest adsorption capacity of
treated CFA was found 5.73 x 10-4mol.g-1.
Abstract: Zeolite A and MCM-41 have extensive applications in basic science, petrochemical science, energy conservation/storage, medicine, chemical sensor, air purification, environmentally benign composite structure and waste remediation. However, the use of zeolite A and MCM-41 in these areas, especially environmental remediation, are restricted due to prohibitive production cost. Efficient recycling of and resource recovery from coal fly ash has been a major topic of current international research interest, aimed at achieving sustainable development of human society from the viewpoints of energy, economy, and environmental strategy. This project reported an original, novel, green and fast methods to produce nano-porous zeolite A and MCM-41 materials from coal fly ash. For zeolite A, this novel production method allows a reduction by half of the total production time while maintaining a high degree of crystallinity of zeolite A which exists in a narrower particle size distribution. For MCM-41, this remarkably green approach, being an environmentally friendly process and reducing generation of toxic waste, can produce pure and long-range ordered MCM-41 materials from coal fly ash. This approach took 24 h at 25 oC to produce 9 g of MCM-41 materials from 30 g of the coal fly ash, which is the shortest time and lowest reaction temperature required to produce pure and ordered MCM-41 materials (having the largest internal surface area) compared to the values reported in the literature. Performance evaluation of the produced zeolite A and MCM-41 materials in wastewater treatment and air pollution control were reported. The residual fly ash was also converted to zeolite Na-P1 which showed good performance in removal of multi-metal ions in wastewater. In wastewater treatment, compared to commercial-grade zeolite A, adsorbents produced from coal fly ash were effective in removing multi heavy metal ions in water and could be an alternative material for treatment of wastewater. In methane emission abatement, the zeolite A (produced from coal fly ash) achieved similar methane removal efficiency compared to the zeolite A prepared from pure chemicals. This report provides the guidance for production of zeolite A and MCM-41 from coal fly ash by a cost-effective approach which opens potential applications of these materials in environmental industry. Finally, environmental and economic aspects of production of zeolite A and MCM-41 from coal fly ash were discussed.
Abstract: Coal will continue to be the predominant source of
global energy for coming several decades. The huge generation of fly
ash (FA) from combustion of coal in thermal power plants (TPPs) is
apprehended to pose the concerns of its disposal and utilization. FA
application based on its typical characteristics as soil ameliorant for
agriculture and forestry is the potential area, and hence the global
attempt. The inferences drawn suffer from the variations of ash
characteristics, soil types, and agro-climatic conditions; thereby
correlating the effects of ash between various plant species and soil
types is difficult. Indian FAs have low bulk density, high water
holding capacity and porosity, rich silt-sized particles, alkaline
nature, negligible solubility, and reasonable plant nutrients. Findings
of the demonstrations trials for more than two decades from lab/pot
to field scale long-term experiments are developed as FA soil
amendment technology (FASAT) by Central Institute of Mining and
Fuel Research (CIMFR), Dhanbad. Performance of different crops
and plant species in cultivable and problematic soils, are
encouraging, eco-friendly, and being adopted by the farmers. FA
application includes ash alone and in combination with
inorganic/organic amendments; combination treatments including
bio-solids perform better than FA alone. Optimum dose being up to
100 t/ha for cultivable land and up to/ or above 200 t/ha of FA for
waste/degraded land/mine refuse, depending on the characteristics of
ash and soil. The elemental toxicity in Indian FA is usually not of
much concern owing to alkaline ashes, oxide forms of elements, and
elemental concentration within the threshold limits for soil
application. Combating toxicity, if any, is possible through
combination treatments with organic materials and phytoremediation.
Government initiatives through extension programme
involving farmers and ash generating organizations need to be
accelerated
Abstract: This study demonstrates the use of Class F fly ash in
combination with lime or lime kiln dust in the full depth reclamation
(FDR) of asphalt pavements. FDR, in the context of this paper, is a
process of pulverizing a predetermined amount of flexible pavement
that is structurally deficient, blending it with chemical additives and
water, and compacting it in place to construct a new stabilized base
course. Test sections of two structurally deficient asphalt pavements
were reclaimed using Class F fly ash in combination with lime and
lime kiln dust. In addition, control sections were constructed using
cement, cement and emulsion, lime kiln dust and emulsion, and mill
and fill. The service performance and structural behavior of the FDR
pavement test sections were monitored to determine how the fly ash
sections compared to other more traditional pavement rehabilitation
techniques. Service performance and structural behavior were
determined with the use of sensors embedded in the road and Falling
Weight Deflectometer (FWD) tests. Monitoring results of the FWD
tests conducted up to 2 years after reclamation show that the cement,
fly ash+LKD, and fly ash+lime sections exhibited two year resilient
modulus values comparable to open graded cement stabilized
aggregates (more than 750 ksi). The cement treatment resulted in a
significant increase in resilient modulus within 3 weeks of
construction and beyond this curing time, the stiffness increase was
slow. On the other hand, the fly ash+LKD and fly ash+lime test
sections indicated slower shorter-term increase in stiffness. The fly
ash+LKD and fly ash+lime section average resilient modulus values
at two years after construction were in excess of 800 ksi. Additional
longer-term testing data will be available from ongoing pavement
performance and environmental condition data collection at the two
pavement sites.