scholarly journals Mineralogy and chemical composition of technogenic soils (Technosols) developed from fly ash and bottom ash from selected thermal power stations in Poland

2015 ◽  
Vol 66 (2) ◽  
pp. 82-91 ◽  
Author(s):  
Łukasz Uzarowicz ◽  
Zbigniew Zagórski
Keyword(s):  
Fly Ash ◽  
Chemical Composition ◽  
Iron Oxides ◽  
Mineral Composition ◽  
Coal Combustion ◽  
Bituminous Coal ◽  
Bottom Ash ◽  
Major Elements ◽  
Soil Horizons ◽  
Technogenic Soils

Abstract The aim of the study was to determine the mineral and chemical composition of technogenic soils (Technosols) developed from fly ash and bottom ash from power plants in which bituminous coal and lignite was combusted. The mineral composition of the “fresh” wastes (i.e. fly ash and bottom ash) and soil samples derived from them was examined by X-ray diffraction (XRD) and using a scanning electron microscope (SEM). The chemical composition (content of major elements) was determined using ICP-AES method. Quartz, mullite, and amorphous substances (glass) predominated in the mineral composition of wastes after bituminous coal combustion. Magnetite was also found there. Soils developed from wastes after bituminous coal combustion contained all above mentioned minerals inherited from fly ash and bottom ash. Moreover, small amounts of secondary calcite were identified. In some soil horizons containing large amounts of inherited magnetite, secondary iron oxides and oxyhydroxides (goethite and lepidocrocite) also occurred. Quartz predominated in the mineral composition of the “fresh” wastes after lignite combustion. Relatively small amounts of iron oxides (magnetite and hematite) were also found there. In “fresh” fly ash, apart from minerals mentioned above, anhydrite and calcium oxide (lime) was identified. Soils developed from wastes after lignite combustion contained inherited quartz, magnetite, and hematite. Furthermore, calcite which sometimes was a predominating mineral in certain soil horizons occurred. Moreover, sulphates (gypsum, bassanite, and ettringite), and vaterite (a polymorph of Ca carbonate) were also found in soils. Silicon predominated among major elements in “fresh” ashes after bituminous coal combustion and soil derived from them followed by Al, Fe, K, Ca, Mg, Ti, Na, P, and Mn. On the other hand, the contents of major elements in the samples (ashes and soils) after lignite combustion can be arranged as follows: Si, Ca, Fe, Al, Mg, Ti, K, Mn, Na, and P. However, in some horizons (i.e. in calcareous materials deposited in the topsoil of some profiles) in soil developed on landfills near TPSs combusting lignite, Ca was a predominating element.

Influence of Different Mineral Precursors on the Properties of Fly Ash Based Alkali-Activated Mortars

2018 ◽  
Vol 761 ◽  
pp. 73-78 ◽  
Author(s):  
Matej Špak ◽  
Pavel Raschman
Keyword(s):  
Mechanical Properties ◽  
Fly Ash ◽  
Chemical Composition ◽  
Coal Combustion ◽  
Pure Aluminum ◽  
Partial Replacement ◽  
Black Coal ◽  
Fly Ashes ◽  
Final Composition ◽  
Alkali Activated

Alkali-activated materials based on fly ash are widely developed and also produced on the present. Some of fly ashes are not suitable for production of alkali-activated materials because of their inconvenient chemical composition. Alumina-silicates are the most important components that are needed to accomplish the successful reaction. The proper content of amorphous phase of alumina-silicates and its proportion as well should be provided for the final composition of alkali-activated materials. The influence of pure aluminum oxide powder as well as raw milled natural perlite on mechanical properties and durability of alkali-activated mortars was investigated. These minerals were used as partial replacement of fly ash coming from black coal combustion. In addition, the mortars were prepared by using different alkali activators.

Modeling of Alteration Behavior on Blended Cementitious Materials

2011 ◽  
Author(s):  
Hitoshi Owada ◽  
Tomoko Ishii ◽  
Mayumi Takazawa ◽  
Hiroyasu Kato ◽  
Hiroyuki Sakamoto ◽  
...  
Keyword(s):  
Blast Furnace ◽  
Fly Ash ◽  
Chemical Composition ◽  
Mineral Composition ◽  
Blast Furnace Slag ◽  
Fine Powder ◽  
Cementitious Materials ◽  
Leaching Tests ◽  
Measured Concentration ◽  
Furnace Slag

A “realistic alteration model” is needed for various cementitious materials. Hypothetical settings of mineral composition calculated based on the chemical composition of cement, such as Atkins’s model, have been used to estimate the alteration of cementitious material. However, model estimates for the concentration of certain elements such as Al and S in leachate have been different from experimental values. In a previous study, we created settings for a mineralogical alteration model by taking the initial chemical composition of cementitious materials from analysis results in experiments and applying their ratios to certain hydrated cement minerals, then added settings for secondary generated minerals in order to account for Ca leaching. This study of alteration estimates for ordinary portland cement (OPC) in groundwater showed that the change in Al and S concentrations in simulated leachate approached values for actual leachate[1]. In the present study, we develop an appropriate mineral alteration model for blended cementitious materials and conduct batch-type leaching experiments that use crushed samples of blast furnace slag cement (BFSC), silica cement (SC), and fly ash cement (FAC). The cement blends in these experiments used OPC blended with blast furnace slag of 70 wt.%, silica cement consisting of an amorphous silica fine powder of 20 wt.%, and fly ash of 30 wt.%. De-ionized water was used as the leaching solution. The solid-liquid ratios in the leaching tests were varied in order to simulate the alteration process of cement hydrates. The compositions of leachate and minerals obtained from leaching tests were compared with those obtained from models using hypothetical settings of mineral composition. We also consider an alteration model that corresponds to the diversity of these materials. As a result of applying the conventional OPC model to blended cementitious materials, the estimated Al concentration in the aqueous solution was significantly different from the measured concentration. We therefore propose an improved model that takes better account of Al behavior by using a more reliable initial mineral model for Al concentration in the solution.

scholarly journals Characteristics of high carbon ash as a raw material for spontaneous combustion inhibitor and its field demonstration

2020 ◽  
Author(s):  
Seok Un Park ◽  
Jae Kwan Kim ◽  
Dong Ik Shin
Keyword(s):  
Fly Ash ◽  
Power Plants ◽  
Bituminous Coal ◽  
Spontaneous Combustion ◽  
Bottom Ash ◽  
Frequency Factor ◽  
Raw Material ◽  
Unburned Carbon ◽  
Mixing Ratio ◽  
High Carbon

Abstract In this study, we examined the physical chemistry, fuel characteristics and combustion reactivity of high carbon ash as a raw material for spontaneous combustion inhibitor in order to solve the problem of spontaneous combustion which has been often occurring in coal yard of coal-fired power plants in Korea. The high carbon ash has higher activation energy and lower frequency factor than bituminous coal, so combustion began at a relatively higher temperature than bituminous coal. In case of fly ash, the heat transfer characteristics were better than those of bottom ash and pond ash, and in case of coarse particles of fly ash, they were found to be highly applicable as a raw material for spontaneous combustion inhibitor due to their relatively high unburned carbon content. As a result of manufacturing spontaneous combustion inhibitors along with asphalt and PFAD (palm fatty acid distillate), the contact angle to water was more than 90° regardless of the mixing ratio, showing hydrophobic surface characteristics, and it was found that the hardness and viscosity of spontaneous combustion inhibitors increased as the mixing ratio of high carbon ash increased. In addition, when spontaneous combustion inhibitors manufactured were applied to coal stockpiles in coal yard at coal-fired power plants, there was little change in the internal temperature of coal stockpiles and the highest value of instantaneous increasing rate per minute was found to be lowered from 1.60°C/min to 0.061°C/min, indicating that spontaneous combustion inhibitors using high carbon coal ash had a great effect of preventing spontaneous combustion.

Effect of CaO and Fe2O3 on Partitioning of As and S within Ash Fractions from Fluidised-Bed Co-Combustion of Coal and Wastes

2018 ◽  
Vol 11 (1) ◽  
pp. 81-90
Author(s):  
Lucie Bartoňová
Keyword(s):  
Fly Ash ◽  
Flue Gas ◽  
Coal Combustion ◽  
Bottom Ash ◽  
Correlation Coefficients ◽  
Fluidised Bed ◽  
Solid Product ◽  
Gas Cleaning

Possible interaction of volatilized As and S with CaO and Fe2O3 (creating solid product) could efficiently improve coal combustion flue gas cleaning. For this reason, S-CaO, As-CaO, S- Fe2O3 and As- Fe2O3 relationships were evaluated in bottom ash and fly ash fractions from fluidised-bed co-combustion of coal and wastes (and limestone as desulphurization additive) through calculation of correlation coefficients and composition of magnetic concentrates. It was concluded that S exhibited a dominant association with CaO while As exhibited affinity to both CaO and Fe2O3 - the significance differed a little in bottom ash and fly ash. In the bottom ash, the affinity of As to CaO was more significant, while in the fly ash the association to Fe2O3 slightly prevailed.

An Overview of Fly Ash and Bottom Ash Replacement in Self-Compaction Concrete

2013 ◽  
Vol 594-595 ◽  
pp. 465-470 ◽  
Author(s):  
Aeslina binti Abdul Kadir ◽  
Mohd Ikhmal Haqeem Hassan
Keyword(s):  
Fly Ash ◽  
Coal Combustion ◽  
Building Materials ◽  
Bottom Ash ◽  
Coal Ash ◽  
Limestone Powder ◽  
Conventional Concrete ◽  
Hydraulic Lime ◽  
Pollution Problem ◽  
Labor Requirements

Over the centuries, concrete is commonly been used in construction world due to its properties. From the conventional concrete until the concrete that has been diversify with innovations, the usefulness is still the same, which is as building materials. One of the innovations called Self-Compaction Concrete (SCC). SCC is a type of concrete that does not require any mechanical compaction at all. This type of concrete will leveled and compacted under its self-weight. Such concrete will accelerate the placement, reduce the labor requirements needed for consolidation, finishing and eliminate environmental pollution. In terms of sustainability, previous researchers have recycled so many waste in SCC for example coal ash, silica fume, hydraulic lime, rice husk ash and fine limestone powder. Recently, recycling fly ash and bottom ash in SCC has grasped the attention of researchers as it demonstrated promising results. Furthermore, previous investigations already confirmed the potential of fly ash and bottom ash in replacing aggregates in SCC represents a better option than landfill and at the same time will decrease pollution problem especially in coal combustion area. This paper reviews the fly ash and bottom ash replacement in SCC.

A review on fly ash from coal-fired power plants: chemical composition, regulations, and health evidence

2020 ◽  
Vol 35 (4) ◽  
pp. 401-418 ◽  
Author(s):  
Kristina M. Zierold ◽  
Chisom Odoh
Keyword(s):  
Fly Ash ◽  
Chemical Composition ◽  
Power Plants ◽  
Waste Product ◽  
Bottom Ash ◽  
Coal Ash ◽  
Epidemiological Studies ◽  
The World ◽  
Main Component ◽  
Surface Impoundments

AbstractThroughout the world, coal is responsible for generating approximately 38% of power. Coal ash, a waste product, generated from the combustion of coal, consists of fly ash, bottom ash, boiler slag, and flue gas desulfurization material. Fly ash, which is the main component of coal ash, is composed of spherical particulate matter with diameters that range from 0.1 μm to >100 μm. Fly ash is predominately composed of silica, aluminum, iron, calcium, and oxygen, but the particles may also contain heavy metals such as arsenic and lead at trace levels. Most nations throughout the world do not consider fly ash a hazardous waste and therefore regulations on its disposal and storage are lacking. Fly ash that is not beneficially reused in products such as concrete is stored in landfills and surface impoundments. Fugitive dust emissions and leaching of metals into groundwater from landfills and surface impoundments may put people at risk for exposure. There are limited epidemiological studies regarding the health effects of fly ash exposure. In this article, the authors provide an overview of fly ash, its chemical composition, the regulations from nations generating the greatest amount of fly ash, and epidemiological evidence regarding the health impacts associated with exposure to fly ash.

scholarly journals Indicators of pedogenesis of Technosols developed in an ash settling pond at the Bełchatów thermal power station (central Poland)

2018 ◽  
Vol 69 (1) ◽  
pp. 49-59 ◽  
Author(s):  
Łukasz Uzarowicz ◽  
Wojciech Kwasowski ◽  
Olga Śpiewak ◽  
Marcin Świtoniak
Keyword(s):  
Organic Matter ◽  
Fly Ash ◽  
Soil Organic Matter ◽  
Total Nitrogen ◽  
Thermal Power Station ◽  
Thermal Power ◽  
Bottom Ash ◽  
Power Station ◽  
Settling Pond ◽  
Technogenic Soils

Abstract Technogenic soils (Technosols) developed in an ash settling pond at the Bełchatów thermal power station, central Poland, were studied in order to identify soil property transformations over 30 years of pedogenesis. Standard pedological methods were applied in order to determine the properties of the studied samples. All investigated soils were classified according to WRB as Spolic Technosols with various supplementary qualifiers (Alcalic/Hypereutric, Arenic/Loamic, Protocalcic, Hyperartefactic, Immisic, Laxic, Ochric, and Protosalic). The studied materials can be arranged into a chronosequence starting from fresh (unweathered) ashes, by young Technosol BE1 (age: several months), up to older Technosols BE2 (about 20 years) and BE3 (about 30 years). The studies showed that weathering and soil-forming processes changed properties of ash in soil environment. Fresh ash was characterized by high pH (11.0 – fly ash, 8.7 – bottom ash), low content of carbonates (1.5% in both samples), variable concentrations of TOC (1.2% – fly ash, 6.9% – bottom ash), and very low total nitrogen content (0.04%). Electrical conductivity (ECe) was 2.6 and 2.1 dS·m−1 in fly ash and bottom ash respectively. Young Technosol BE1 had the pH 9.2–10.0, contents of carbonates were in the range 2.4–3.3%, TOC 1.3–1.7%, and total nitrogen less than 0.03%. ECe in young Technosol was in the range 2.7–4.0 dS·m−1. There was no plant cover present on that soil and no well-developed genetic horizons were distinguished in the profile. Finally, old Technosols BE2 and BE3 had lower pH (from 7.9 up to 9.1), and, in general, higher contents of carbonates (from 1.5 to 7.9%) than fresh ash and young Technosol BE1. Old Technosols contained high concentrations of TOC (up to about 38% in Oi horizon) and total nitrogen (up to 0.9%) in the topsoil, where O and A horizons developed due to accumulation of soil organic matter. ECe in old Technosols was in the range 0.8–1.5 dS·m−1. All studied ashes and soils were characterized by very low or even absence of total potential acidity. Base cations predominated in the sorption complex of the investigated ash and soils and can be arranged in the following order according to the abundance: Ca>Mg>K>Na. Base saturation (BS) of fresh ashes and Technosols was nearly 100%. The study shows that the first indicators of pedogenesis of the studied technogenic soils within the first 30 years of formation are: (1) changes of consistence of ash material from firm to friable/very friable due to root action, (2) accumulation of soil organic matter in the topsoil and formation of O and A horizons, (3) decrease of pH, (4) formation of pedogenic carbonates in soils and (5) decrease in soil salinity.

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