The removal of As(V) ions by lime-modified fly ash and reuse of the exhausted adsorbent as an additive for construction material

2020 ◽  
Author(s):  
Milica Karanac ◽  
Maja Đolić ◽  
Vladimir Pavićević ◽  
Aleksandar Marinković
Keyword(s):  
Fly Ash ◽  
Power Plants ◽  
Low Cost ◽  
Construction Material ◽  
Thermal Power ◽  
Construction Materials ◽  
Practical Applications ◽  
The Impact ◽  
By Products ◽  
Modified Fly Ash

<p>Coal thermal power plants (TPP) actively generate numerous solid combustion by-products, including fly ash and bottom ash. These TPP by-products have already found use in a variety of civil engineering applications, such as a substitute for sand and gravel in structures, as well as a binding component in certain types of cement (generally, concrete and masonry). Furthermore, such by-products have become a subject of increasing interest in environmental engineering as a low-cost and effective adsorbent for the removal of organic pollutants and heavy metals from wastewaters.</p><p>In order to minimize the impact of material cost, novel solutions for the development of a high capacity and long-term adsorbent have provided a high performance adsorbent for practical applications. This study is focused on the use of modified fly ash (MFA) activated by lime (Ca(OH)<sub>2</sub>) as an effective and low-cost adsorbent for the removal of As(V) ions. The adsorption capacity of the MFA adsorbent was found to be 35.40 mg g<sup>-1</sup>, while the kinetic and thermodynamic parameters indicated a spontaneous and endothermic process. Due to the low desorption potential of the exhausted adsorbent (MFA/As(V), their effective further material reuse was established to be feasible. The reuse of the exhausted adsorbent was obtained through pozzolanic MFA particles and Ca(OH)<sub>2, </sub>thereby formulating a construction material of a cementitious calcium-silicate hydrate. The toxicity leaching test (TCLP) and mechanical properties of the new construction material containing exhausted MFA (CM-MFA/As(V)) confirm its safe use in the laboratory as well as its semi-industrial application.</p><p>The specific objectives of this study have been: (i) to improve the adsorption performance of the MFA; (ii) to evaluate the material’s equilibrium, as well as the process’ kinetic and thermodynamic aspects, including  estimating its limiting step; and (iii) to investigate the possible reuse of the exhausted adsorbent in the production of construction materials. The kinetic data were successfully fitted by a pseudo-second-order equation and the Weber-Morris model. The metal-desorption experiments performed on the exhausted FA and MFA indicate a low recovery of the selected pollutants.</p><p>The major outcome of this study, indicates that double-valorization of fly ash opens new directions for waste management toward reuse in effective practical applications; i.e., for actual water –purification systems, as well as in the production of construction material.</p>

The Latest Research in Mongolia on the Utilization of Coal Combustion By-Products

2021 ◽  
Vol 323 ◽  
pp. 8-13
Author(s):  
Jadambaa Temuujin ◽  
Damdinsuren Munkhtuvshin ◽  
Claus H. Ruescher
Keyword(s):  
Compressive Strength ◽  
Fly Ash ◽  
Coal Combustion ◽  
Power Plants ◽  
Thermal Power ◽  
Thermal Power Plants ◽  
Power Stations ◽  
Thermal Power Stations ◽  
Coal Ashes ◽  
By Products

With a geological reserve of over 170 billion tons, coal is the most abundant energy source in Mongolia with six operating thermal power stations. Moreover, in Ulaanbaatar city over 210000 families live in the Ger district and use over 800000 tons of coal as a fuel. The three thermal power plants in Ulaanbaatar burn about 5 million tons of coal, resulting in more than 500000 tons of coal combustion by-products per year. Globally, the ashes produced by thermal power plants, boilers, and single ovens pose serious environmental problems. The utilization of various types of waste is one of the factors determining the sustainability of cities. Therefore, the processing of wastes for re-use or disposal is a critical topic in waste management and materials research. According to research, the Mongolian capital city's air and soil quality has reached a disastrous level. The main reasons for air pollution in Ulaanbaatar are reported as being coal-fired stoves of the Ger residential district, thermal power stations, small and medium-sized low-pressure furnaces, and motor vehicles. Previously, coal ashes have been used to prepare advanced materials such as glass-ceramics with the hardness of 6.35 GPa, geopolymer concrete with compressive strength of over 30 MPa and zeolite A with a Cr (III) removal capacity of 35.8 mg/g. Here we discuss our latest results on the utilization of fly ash for preparation of a cement stabilized base layer for paved roads, mechanically activated fly ash for use in concrete production, and coal ash from the Ger district for preparation of an adsorbent. An addition of 20% fly ash to 5-8% cement made from a mixture of road base gave a compressive strength of ~ 4MPa, which exceeds the standard. Using coal ashes from Ger district prepared a new type of adsorbent material capable of removing various organic pollutants from tannery water was developed. This ash also showed weak leaching characteristics in water and acidic environment, which opens up an excellent opportunity to utilize.

The Suitability of Fly Ash for Use in Concrete According to EN 450 Based on their Particle Size

2018 ◽  
Vol 276 ◽  
pp. 110-115
Author(s):  
Martin Ťažký ◽  
Martin Labaj ◽  
Rudolf Hela
Keyword(s):  
Fly Ash ◽  
Power Plants ◽  
Catalytic Reduction ◽  
Raw Materials ◽  
Thermal Power ◽  
Combustion Process ◽  
Thermal Power Plants ◽  
Mechanical Parameters ◽  
Fly Ashes ◽  
The Impact

The by-products of energy industry are nowadays often affected by new limits governing the production of harmful gases discharged into the air. These stricter and stricter criteria are often met by electricity producers by changing the combustion process in thermal power plants itself. Nowadays, the SNCR (selective non-catalytic reduction) application is quite common in the combustion process in order to help reduce the nitrogen oxide emission. This article deals with the primary measures of thermal power plants, which in particular consist of a modified treatment of raw materials (coal) entering the combustion process. These primary measures then often cause the formation of fly ash with unsuitable fineness for the use in concrete according to EN 450. The paper presents the comparison of the physico-mechanical parameters of several fly ashes with a different fineness values. The primary task is to assess the impact of non-suitable granulometry in terms of EN 450 on the other physico-mechanical parameters of fly ashes sampled within the same thermal power plant. Several fly ashes produced in the Czech Republic and surrounding countries were evaluated in this way.

scholarly journals Influence of Activators on Mechanical Properties of Modified Fly Ash Based Geopolymer Mortars

Materials ◽  
2020 ◽  
Vol 13 (5) ◽  
pp. 1033 ◽  
Author(s):  
Piotr Prochon ◽  
Zengfeng Zhao ◽  
Luc Courard ◽  
Tomasz Piotrowski ◽  
Frédéric Michel ◽  
...  
Keyword(s):  
Fly Ash ◽  
Power Plants ◽  
Thermal Power ◽  
Biomass Combustion ◽  
Fly Ashes ◽  
Binding Properties ◽  
Alkali Activated ◽  
Modified Fly Ash ◽  
Scanning Electron ◽  
And Calorimetry

The aim of this work was to study the influence of the type of activator on the formulation of modified fly ash based geopolymer mortars. Geopolymer and alkali-activated materials (AAM) were made from fly ashes derived from coal and biomass combustion in thermal power plants. Basic activators (NaOH, CaO, and Na2SiO3) were mixed with fly ashes in order to develop binding properties other than those resulting from the use of Portland cement. The results showed that the mortars with 5 mol/dm3 of NaOH and 100 g of Na2SiO3 (N5-S22) gave a greater compressive strength than other mixes. The compressive strengths of analyzed fly ash mortars with activators N5-S22 and N5-C10 (5 mol/dm3 NaOH and 10% CaO) varied from 14.3 MPa to 5.9 MPa. The better properties of alkali-activated mortars with regular fly ash were influenced by a larger amount of amorphous silica and alumina phases. Scanning electron microscopy and calorimetry analysis provided a better understanding of the observed mechanisms.

scholarly journals Application of Electro kinetic technique to remediate fly ash for its sustainable use

2020 ◽  
Vol 12 (4) ◽  
pp. 682-687
Author(s):  
Shristi Choudhary ◽  
N. Srinivas
Keyword(s):  
Fly Ash ◽  
Coal Combustion ◽  
Power Plants ◽  
Low Cost ◽  
Thermal Power ◽  
Sustainable Use ◽  
Voltage Gradient ◽  
Ph Values ◽  
Cost Treatment ◽  
Remediation Process

Fly ash is a by-product of coal combustion in thermal power plants which is classified as hazardous waste and a serious threat to environment. The study was conducted to determine the potential and examine the efficacy of electro kinetic technique (EKT) using variables like pH, total dissolved solids (TDS), e concentration of chlorides (Cl-), sodium (Na+),magnesium (Mg2+), potassium (K+), ammonia (NH3+) and calcium (Ca2+) on fly ash as a low-cost treatment for enhancing the use of fly ash in a more sustainable manner. The probability of removing heavy metals and chlorides from fly ash suspended in water using electro dialysis was studied as they are highly dependent on pH and conductivity of the fly ash. The voltage gradient and duration indicated significant effect in the change of pH values showing a range from 4.6 to 7.7 at cathode and anode respectively, while the Total dissolves solids (TDS) varying from 72.33±5.6 to 146±5.4 showed the enhanced availability of ions post electro dialysis. In terms of chlorides, Cl- the content was observed to be 265.06 mg/l which was high enough to cause corrosion problems in later stages of reuse of fly ash. The concentration of cations like Na+, K+, NH3+, Mg2+, Ca2+ were observed to be notably influenced by the duration of study and pH in electro dialysis. The experimental results of the study showed that the proposed technique based on the fundamentals of electro kinetics and dialysis could efficiently improve the remediation process which would remove metals by converting them to available form in fly ash.

scholarly journals Design of Rigid Pavement by Self Cured Concrete Utilizing Coarse Fly Ash Aggregates and Curing Admixture

2021 ◽  
Vol 889 (1) ◽  
pp. 012011
Author(s):  
Ajay Rana ◽  
Abhishek Sharma ◽  
Kshitij Jassal
Keyword(s):  
Fly Ash ◽  
Flexural Strength ◽  
Power Plants ◽  
Thermal Power ◽  
Waste Product ◽  
Partial Replacement ◽  
Rigid Pavement ◽  
Natural Aggregates ◽  
The Impact ◽  
Ash Aggregates

Abstract In concrete industry, a huge amount of natural aggregates is used in the making of concrete every day. The environment is being exploited by mining for the gain of natural aggregates, resulting in an environmental instability in nature. As a result, an alternate source to substitute natural aggregates in concrete is required. A lot of waste materials have gain attention now a days into the concrete industry as a substitute to natural materials. Fly ash, a waste product of thermal power plants, meets the criterion for being utilised as an aggregate substitute in concrete because of its pozzolanic activity. Coarse fly ash is manufactured using a good manufacturing method and is light in weight. Keeping this into view, the impact of partial replacement of natural coarse aggregates with coarse fly ash aggregates produced using the colds bonded method is explored in this paper. The major focus of this study is on testing for flexural strength of self-cured concrete, as flexural strength is a key criterion for rigid pavement design. In this study, coarse fly ash aggregates are utilised in concrete in different proportions to substitute natural aggregates, and the optimal value for flexural strength is determined using a curing additive. The findings of this experiment indicated that when fly ash aggregates and curing additives were used optimally, the flexure strength improved, which is enough for the construction of rigid pavement as criteria fixed by Indian Standards.

scholarly journals Processing of high-grade zeolite nanocomposites from solid fuel combustion by-products as critical raw materials substitutes

2020 ◽  
Vol 7 ◽  
pp. 22
Author(s):  
Silviya Boycheva ◽  
Denitza Zgureva ◽  
Hristina Lazarova ◽  
Katerina Lazarova ◽  
Cyril Popov ◽  
...  
Keyword(s):  
Fly Ash ◽  
Power Plants ◽  
Raw Materials ◽  
Coal Fly Ash ◽  
Thermal Power ◽  
Coal Ash ◽  
High Grade ◽  
Fly Ash Zeolite ◽  
By Products ◽  
Critical Raw Materials

High-grade zeolite nanocomposites are synthesized utilizing solid by-products from combustion of coal for energy production in Thermal Power Plants applying alkaline aging, hydrothermal and fusion-hydrothermal activation procedures. The obtained coal ash zeolites were studied with respect to their chemical and phase composition, morphology, surface parameters and thermal properties. It was found that they are distinguished in nanocrystalline morphology and significant content of iron oxide nanoparticles (γ-Fe2O3, α-Fe2O3, γ-Fe3O4) and doping elements (Cu, Co, Mn, V, W, etc.) transferred from the raw coal ash, and therefore they are assumed as nanocomposites. Coal fly ash zeolite nanocomposites are characterized by a mixed micro-mesoporous texture, significant concentration of acidic Brønsted centers due to their high surface insaturation, high chemical and thermal stabilty. This unique combination of compositional and textural properties predetermines the application of these materials as catalysts for thermal oxidation processes, anticorrosion barrier coatings, carbon capture adsorbents, matrices for hosting functional groups, detergents etc. Examples for coal fly ash zeolite applications for substitution of critical raw materials in practice are provided.

scholarly journals Study on the Preparation and Properties of Talcum-Fly Ash Based Ceramic Membrane Supports

Membranes ◽  
2020 ◽  
Vol 10 (9) ◽  
pp. 207
Author(s):  
Chao Cheng ◽  
Hongming Fu ◽  
Jun Wu ◽  
Heng Zhang ◽  
Haiping Chen
Keyword(s):  
Fly Ash ◽  
Flue Gas ◽  
Power Plants ◽  
Ceramic Membrane ◽  
Low Cost ◽  
Thermal Power ◽  
Water Flux ◽  
Ceramic Membranes ◽  
Operating Conditions ◽  
Water Recovery

Ceramic membrane method for moisture recovery from flue gas of thermal power plants is of considerable interest due to its excellent selection performance and corrosion resistance. However, manufacturing costs of commercial ceramic membranes are still relatively expensive, which promotes the development of new methods for preparing low-cost ceramic membranes. In this study, a method for the preparation of porous ceramic membrane supports is proposed. Low-cost fly ash from power plants is the main material of the membrane supports, and talcum is the additive. The fabrication process of the ceramic membrane supports is described in detail. The properties of the supports were fully characterized, including surface morphology, phase composition, pore diameter distribution, and porosity. The mechanical strength of the supports was measured. The obtained ceramic membrane supports displays a pore size of about 5 μm and porosity of 37.8%. Furthermore, the water recovery performance of the supports under different operating conditions was experimentally studied. The experimental results show that the recovered water flux varies with operating conditions. In the study, the maximum recovered water flux reaches 5.22 kg/(m2·h). The findings provide a guidance for the ceramic membrane supports application of water recovery from flue gas.

scholarly journals Fly Ash-Based Geopolymer Binder: A Future Construction Material

Minerals ◽  
2018 ◽  
Vol 8 (7) ◽  
pp. 299 ◽  
Author(s):  
Nakshatra Singh
Keyword(s):  
Fly Ash ◽  
Coming Out ◽  
Power Plants ◽  
Construction Material ◽  
Thermal Power ◽  
Raw Material ◽  
Thermal Power Plants ◽  
Portland Cement Concrete ◽  
Waste Production ◽  
Alternative Material

A large amount of waste coming out from industries has posed a great challenge in its disposal and effect on the environment. Particularly fly ash, coming out from thermal power plants, which contains aluminosilicate minerals and creates a lot of environmental problems. In recent years, it has been found that geopolymer may give solutions to waste problems and environmental issues. Geopolymer is an inorganic polymer first introduced by Davidovits. Geopolymer concrete can be considered as an innovative and alternative material to traditional Portland cement concrete. Use of fly ash as a raw material minimizes the waste production of thermal power plants and protects the environment. Geopolymer concretes have high early strength and resistant to an aggressive atmosphere. Methods of preparation and characterization of fly ash-based geopolymers have been presented in this paper. The properties of geopolymer cement/mortar/concrete under different conditions have been highlighted. Fire resistance properties and 3D printing technology have also been discussed.

scholarly journals Production and Characterization of Porous Ceramics From Coal Fly Ash and Clay

2017 ◽  
Vol 14 (3-4) ◽  
Author(s):  
Biljana Angjusheva ◽  
Emilija Fidancevska ◽  
Vojo Jovanov
Keyword(s):  
Fly Ash ◽  
Power Plants ◽  
Bending Strength ◽  
Coal Fly Ash ◽  
Porous Ceramic ◽  
Thermal Power ◽  
Construction Materials ◽  
Porous Ceramics ◽  
Significant Research ◽  
Different Content

The disposal of coal fly ash obtained in thermal power plants presents the general problem all over the world. Significant research on the utilization of fly ash has been carried out in the area of construction materials. The aim of this study was to develop porous ceramics based on coal fly ash and clay (60wt.%clay and 40wt.% fly ash). Three types of pore creators: two types of wood cutting (Quercus and Facus sylvatica) and C-powder were used for creating of the porous ceramics. The mixtures based on fly ash and clay and different content of pore creators (2, 5, 10 and 20wt.%) were consolidated (P=45 MPa, T = 900, 1000, 1050 and 1100oC/1h) to obtain porous ceramic (PC). The results indicate that the properties of the porous ceramics depend on the type and content of the pore creators. Furthermore, the sintering temperature was found to be main factor affecting the properties of the sintered products. The maximal bending strength (26 MPa) was achieved by using 2wt% P3 (C-powder) and the porous ceramics has the density and porosity of 1.90g/cm3 and 22%, respectively. By using the highest content (20wt.% ) of each pore creator (P1, P2 and P3) the lowest bending strength cca 5 MPa was achieved and the variation of the density and porosity was in the range from 1.22 to 1.32 g/cm3 and 44 to 48%, respectively. Water absorption, durability and the microstructure of the obtained porous ceramics are also reported in this paper.

The Usability of Fly Ash for the Construction of Embankment Dams

2012 ◽  
Vol 587 ◽  
pp. 26-30
Author(s):  
Vit Cerný ◽  
Rostislav Drochytka ◽  
Jan Jandora
Keyword(s):  
Fly Ash ◽  
Power Plants ◽  
Thermal Power ◽  
Raw Material ◽  
Site Testing ◽  
The Czech Republic ◽  
Embankment Dams ◽  
Different Types ◽  
Building Area ◽  
By Products

Power supplying industry in the Czech Republic is still dependent on thermal power plants. Due to the on-going and completed renovation of the existing power plant units, it is expected that they will be serviceable for the following 30 years. It is therefore necessary to look for suitable use of the by-products of these plants. Using the energy by-products during construction of dikes is currently limited to creation of little protective dikes on unloading yards of fly ash stabilizers. Here we can take advantage of the binding abilities of the energy by-product to stabilize the unloading yards and protect the environment. This method is technologically less effective for constructions of anti-flood dikes. Therefore we use the soils from the vicinity of the building area. A suitable method of using fly ash in water building industry lies in repairs of existing earth dams by using fly-ash and clay grouting that increase homogeneity, stability and impermeability of the dam. This paper deals with laboratory verification of suitability of different types of fly-ash in the mixture with special sealing clay. It also deals with designing optimal recipes for "on-site" testing. Results of the tests clearly recommend classical fly ash as the most suitable raw material. On the other hand, the bedding ash marked is not suitable for this technology.

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