The use of biomass in the energy industry is the consequence of ongoing efforts to replace Energy from fossil fuels with energy from renewable sources. However, due to the diversity of the biomass, its use as a solid fuel generates waste with diverse and unstable chemical composition. Waste from biomass combustion is a raw material with a very diverse composition, even in the case of using only one type of biomass. The content of individual elements in fly ash from the combustion of biomass ranges from zero to tens of percent. This makes it difficult to determine the optimal recovery methods. The ashes from the combustion of biomass are most commonly used in the production of building materials and agriculture. This article presents the elemental composition of the most commonly used biomass fuels. The results of the analysis of elemental composition of fly ashes from the combustion of forest and agricultural biomass in fluidized bed boilers used in the commercial power industry were presented. These ashes are characterized by a high content of calcium (12.3–19.4%), silicon (1.2–8.3%), potassium (0.05–1.46%), chlorine (1.1–6.1%), and iron (0.8–6.5%). The discussed ashes contained no sodium. Aluminum was found only in one of the five ashes. Manganese, chromium, copper, nickel, lead, zinc, sulfur, bismuth, titanium and zirconium were found in all of the examined ashes. The analysis of elemental composition may allow for a preliminary assessment of the recovery potential of a given ash.
Petrographic and physico-chemical analyses of ashes are carried out on a large scale and presented in numerous scientific papers. The mentioned ashes are obtained from filters and electrostatic precipitators mounted in large industrial installations. The large-scale analysis of the ashes obtained directly from grate furnaces or blast furnaces mounted in low-power boilers started with combating smog and low-stack emissions. The collection of ash samples from household furnaces usually involves the analysis of the combustion of waste in low-power boilers. This is justified in the case of old type boilers, which were designed to use virtually any fuel. Currently, new types of boilers, designed to burn dedicated fuels, are offered on the market. The aim is to use only renewable fuels (biomass) or fossil fuels with high quality parameters, which are more environment-friendly, e.g. eco-pea coal, lignite briquettes, or peat briquettes. The authors of the study focused on examining the ash obtained from boilers for burning wood pellets by performing microscopic analysis of residues after biomass combustion. The above mentioned analysis provides a comprehensive information on the efficiency of the combustion process, the content of contaminants remaining in the ash, and the suitability of ash for other applications. The entire process, from the moment of collecting the samples to the execution of the analysis takes up to 12 hours, which ensures a quick decision on furnace adjustment or fuel change. The ash components were determined based on the results obtained by the Fly-Ash Working Group of the International Committee for Coal and Organic Petrology (ICCP). The mentioned classification has been supplemented with new key elements occurring in ashes resulting from the combustion of wood pellets in household boilers. This allowed determining the percentage content of characteristic components in the tested material, which can be used as a specific benchmark when issuing opinions on the quality and efficiency of the boiler and the combusted pellets.
Concrete is generally produced using materials such as crushed stone and river sand to the extent of about 80‒90% combined with cement and water. These materials are quarried from natural sources. Their depletion will cause strain on the environment. To prevent this, bottom ash produced at thermal power plants by burning of coal has been utilized in this investigation into making concrete. The experimental investigation presents the development of concrete containing lignite coal bottom ash as fine aggregate in various percentages of 25, 50, and 100. Compressive, split tensile, and flexural strength as part of mechanical properties; acid, sulphate attack, and sustainability under elevated temperature as part of durability properties, were determined. These properties were compared with that of normal concrete. It was concluded from this investigation that bottom ash to an extent of 25% can be substituted in place of river sand in the production of concrete.
The problem of of the use of fly ash still constitutes a research and exploration area for scientists. This is due to the fact that, 6,000,000 Mg of coal combustion by-products (CCB) are storage on landfills yearly in Poland alone. One of the potential directions of using fly ash is to use it as a substrate in hydrothermal syntheses of mesoporous materials (synthetic zeolites). Zeolites are aluminosilicates with a spatial structure. Due to their specific structure they are characterized by a number of specific properties among others molecular-sieve, ion-exchange and catalytic that can be used in engineering and environmental protection. So far, the synthesis has been carried out using coal combustion by-products such as fly ash or microsphere. The article analyzes whether separation from the fly ash of the appropriate fraction (below 63 μm) will affect the formation of zeolite grains. The syntheses were carried out using class F fly ash and the fraction separated from it, which was obtained by sieving the ash through a 63 μm sieve. Chemical (XRF) and mineralogical (XRD, SEM-EDS) analyzes were carried out for substrates as well as the obtained reaction products. In the case of substrates, the analysis did not show any significant differences between the ash and the separated fraction. However, in products after synthesis (Na-X zeolite with a small amount of Na-P1 zeolite, and small amounts of quartz and unreacted aluminosilicate glass - mullite) higher aluminum and sodium contents were observed from the separated fraction, with a lower calcium and potassium content. A small proportion of illite was observed on the diffraction curve of the zeolite from the fraction. Observations of grain morphology showed no differences in formation. Based on the conducted analyzes, it can be stated that, considering the economics of the synthesis process, the separation of fine fractions from the fly ash does not affect the quality of the synthesis process.
Fly ash which has been separated from the flue gas stream as a result of fossil fuels combustion constitutes a huge amount of waste generated worldwide. Due to environmental problems, many directions of their rational use have been developed. Various attempts to convert fly ash into sorption materials, mainly synthetic zeolites, are conducted successfully. In this paper, an attempt was made to convert fly ash from lignite combustion from one of the Polish power plants, using alkaline hydrothermal synthesis. The primary phases in the fly ash were: quartz, gehlenite, mullite, hematite, feldspar, lime, anhydrite, occasionally grains of ZnO phase and pyrrhotite, glass and unburned fuel grains. As a result of hydrothermal synthesis a material containing new phases – pitiglianoite and tobermorite was obtained. Among the primary ash constituents, only gehlenite with an unburned organic substance, on which tobermorite with crystallized pitiglianoite was present. As a result of detailed testing of products after synthesis, it was found that among the tested grains: • two populations can be distinguished – grains containing MgO and Fe2O3 as well as grains containing Fe2O3 or MgO or containing none of these components, • the main quantitative component was pitiglianoite, • pitiglianoite was present in larger amounts in grains containing Fe2O3 or MgO or in the absence of both components than in grains in which Fe2O3 and MgO were found. The results of the study indicate that in post-synthesis products, the contribution of components were as follows: pitiglianoite – 39.5% mas., tobermorite – 54% mas., gehlenite – 3% mas. and organic substance – 3.5% mas.
Strength and permeability properties along with microstructural evolution of hardened slurries composed of fly ash from fluidal bed combustion of brown coal and an addition of OPC/BFSC is assessed in this paper. An increase in the amount of fly ash in slurries influences the development of mechanical strength and a decrease of hydraulic conductivity. SEM, XRD, and porosity analyses confirmed formation of watertight microstructures. The structure of slurries is composed of ettringite, C-S-H phase, AFt, and AFm phases. Ettringite crystallises as relatively short needles forming compact clusters or intermixed with the C-S-H phase. The occurring C-S-H phases are mainly of type I – fibrous and type II – honeycomb
In the process of determining the content of impurities, including fossil fuels, crude oil, coke, pitch, plastics, glass, slag, rust, metals, and rock dust, in charcoal and wood briquettes via microscopic examination, the question of the use of ashes from the combustion of grill fuels (taking the scale of the new national sport into account, commonly referred to as „weekend grilling”) was raised. Another reason for addressing this issue was the question regarding the use of organic additives to acidified soil (mineral) fertilizers submitted by one of the clients of the bituminous coal and reservoir rocks analysis laboratory. In addition, the manufacturer of gardening soil has also expressed an interest in an unconventional deacidifying agent; the introduction of a new product with a unique ingredient is considered as a chance to stand out from the competition. A review of the literature shows that attempts to use ashes obtained from the biomass combustion in power boilers have been made. However, due to the biomass composition and additives and pollutants used in biomass for energy purposes, the production of such mixtures has been dropped. Based on the data from numerous samples of grill fuel, which meet the requirements regarding the content of impurities set out in the PN-EN 1860-2 standard, the question of the possible use of ash obtained from charcoal and wood briquette grilling as a component for use in the production of acidified soil (mineral) fertilizers was discussed. The article will present the amount of material obtained based on the statistical sales of barbecue fuels based on the experimentally calculated ash mass resulting from the combustion of 1 kg of starting material. In addition, a logistic proposal for obtaining ash from individual grill users will be developed. On the day of the submission of the present work, the results of the chemical analysis of charcoal and wood briquettes subjected to the gasification process have not yet been obtained. However, based on the microscopic analysis, it can be concluded that the content of impurities in the examined samples is highly unlikely to prevent the use of the mentioned ashes in agriculture.
Based on laboratory tests of selected properties of secondary waste (ashes and dusts) from municipal waste incineration plants, the possibility of recovering some properties of waste in the process of filling the post-mining voids in the salt mine was assessed. The furnace bottom ash and the waste from the flue gas treatment from one of the national incineration plants were examined. The grain curves of dry waste and the density of the prepared mixtures were characterized. Twelve variants of the compositions of ash-based mixtures with varying proportions of the individual components were considered, taking into account both fresh water and brine. For each variant of the composition, the amount of redundant liquid appeared as well as the time of solidifying of the mixture to a certain strength and the compressibility values obtained. Considering the possibility of transporting mixtures in mines by means of pipelines at relatively long distances, and allowing the filling of large salt chambers to be filled and evenly filled, flow parameters were determined. In addition, the permeability of solidified waste samples was investigated, showing the potential for reducing the strength of the waste mass due to the action of water or brine. The technical feasibility of eliminating redundant liquid in the binding process has been confirmed, which is particularly important in salt mines. Preliminary values for the amount of binder (5%÷10%) to be added to the mixtures to obtain the specified strength properties of the artificially formed mass at Rc = 0.5 MPa. Attention was paid to the important practical aspect resulting from the rapid increase of this type of waste in the comming years in Poland and at the same time vast potential for their use in salt mining, where we have a huge capacity of salt chambers available.
Increasing environmental pressure against waste disposal, particularly fine waste surface storage and concern about mining damages have resulted in an increase in the popularity of a fly ash, tailing and binding agent mixture used as compaction grout of roof fall rocks in a gob area of longwalls. Backfilling of voids forming as a result of exploitation with the fall of roof with mixtures containing fine-grained industrial wastes is a common practice in coal mines. It is aimed at achieving numerous technological and ecological advantages as well as at controlling mining hazards. Research on hydraulic transport of fine-grained slurry conducted to date focused mainly on issues related to the analysis of the conditions related to pipeline transportation. The processes concerning the propagation of mixtures within the gob, on the other hand, remain largely unknown. The process of flow of fine-grained slurry through the caving is subject to a series of factors related, among other things, with the properties of the applied wastes and mixtures, the characteristics of the gob as well as the variability of these properties during the flow through the gob and in time. Due to the lack of sufficient knowledge pertaining to the changes taking place in the gob and in the slurry while it penetrates the gobs, no methods allowing for the design and optimization of the gob grouting process have been established so far. The paper presents the selected results of laboratory tests regarding the flow of ash and water mixtures in a model of a gob, pertaining to two selected types of fly ash produced in hard coal combustion, particularly concerning the impact of the type of the ash and the density of the slurry on the effectiveness of the gob grouting process.
The presence of inorganic elements in solid fuels is not only considered a direct source of problems in the furnace but is also connected with the release of pollutants into air during combustion. This article focuses on the sintering characteristics of biomass and coal ashes, in particular on the leaching processes, and their impact on the tendency to sinter ash. Biomass and coal ash with high alkali metal concentration can deposit in boiler sections and cause severe operating problems such as slagging, fouling and corrosion of boiler and heat exchanger surface, limiting heat transfer. Two biomass types and one coal ash with different origin and different chemical compositions were investigated. A sequential leaching analysis was employed in this study to elucidate the modes of occurrence of metals that can transform into fuel extract. Sequential leaching analysis was conducted as a two-step process: using distilled water in the first step and acetic acid in the second step. The chemical composition of ashes, before and after each step of the leaching processwas studied using ICP-OES method. The standard Ash Fusion Temperature (AFTs) technique was also employed to assess the sintering tendency of the tested samples. It was observed that the presence of key elements such as sodium, potassium, magnesium and sulphur (elucidated in the leaching process) plays a significant role in sintering process. The sintering tendency enhances when the concentration of these elements increases.
The issue of mercury emission and the need to take action in this direction was noticed in 2013 via the Minamata Convention. Therefore, more and more often, work and new law regulations are commencing to reduce this chemical compound from the environment. The paper presents the problem of removing mercury from waste gases due to new BREF/BAT restrictions, in which the problem of the need to look for new, more efficient solutions to remove this pollution was also indicated. Attention is paid to the problem of the occurrence of mercury in the exhaust gases in the elemental form and the need to carry out laboratory tests. A prototype installation for the sorption of elemental mercury in a pure gas stream on solid sorbents is presented. The installation was built as part of the LIDER project, financed by the National Center for Research and Development in a project entitled: “The Application of Waste Materials From the Energy Sector to Capture Mercury Gaseous Forms from Flue Gas”. The installation is used for tests in laboratory conditions in which the carrier gas of elemental mercury is argon. The first tests on the zeolite sorbent were made on the described apparatus. The tested material was synthetic zeolite X obtained as a result of a two-stage reaction of synthesis of fly ash type C with sodium hydroxide. Due to an increase, the chemical affinity of the tested material in relation to mercury, the obtained zeolite material was activated with silver ions (Ag+) by an ion exchange using silver nitrate (AgNO3). The first test was specified for a period of time of about 240 minutes. During this time, the breakthrough of the tested zeolite material was not recorded, and therefore it can be concluded that the tested material may be promising in the development of new solutions for capturing mercury in the energy sector. The results presented in this paper may be of interest to the energy sector due to the solution of several environmental aspects. The first of them is mercury sorption tests for the development of new exhaust gases treatment technologies. On the other hand, the second aspect raises the possibility of presenting a new direction for the management and utilization of combustion by-products such as fly ash.
The exploitation and processing of lignite in the Bełchatów region is connected with the formation of various mineral waste materials: varied in origin, mineral and chemical composition and raw material properties of the accompanying minerals, ashes and slags from lignite combustion and reagipsum from wet flue gas desulphurisation installations. This paper presents the results of laboratory tests whose main purpose was to obtain data referring to the potential use of fly ashes generated in the Bełchatów Power Plant and selected accompanying minerals exploited in the Bełchatów Mine in the form of self-solidification mixtures. The beidellite clays were considered as the most predisposed for use from the accompanying minerals , due to pozzolanic and sorption properties and swelling capacity. Despite the expected beneficial effects of clay minerals from the smectite group on the self-settling process as well as the stability of such blends after solidification, the results of physical-mechanical tests (compressive strength and water repellence) were unsatisfactory. It was necessary to use Ca (OH)2, obtained from the lacustrine chalk as an activator of the self-settling process It was necessary to use lacustrine chalk as an activator of the self-solidification process. The presence of calcium will allow the formation of cement phases which will be able to strongly bond the skeletal grains. Also, the addition of reagipsum to the composition of the mixture would contribute to the improvement of the physico-mechanical parameters. The elevated SO4 2– ion in the mixture during the solidification allows for the crystallization of the sulphate phases in the pore space to form bridges between the ash and clay minerals. The use of mixtures in land reclamation unfavourably transformed by opencast mining in the Bełchatów region would result in measurable ecological and economic benefits and would largely solve the problem of waste disposal from the from the operation and processing of lignite energy.
The main energy source in Poland is still hard coal and lignite. The coal combustion process produces large quantities of by-products, e.g. fly ashes, slag furnace and harmful chemical gases (CO2, NOx, sulfur compounds) which enter the atmosphere. Fly ashes, due to their being fine grained (cement-like), chemical and phase compound and reactivity, have also been widely used in various technological solutions e.g. in the production of ordinary cement, hydro-technical cement and the new generation of cements. The adequate amount of fly ashes additive has a positive effect on fresh and hardened cement slurry properties. What is more, it allows for the pro-ecological and economic production of cement mix The exploitation of natural resources is connected with performance mining excavations at different depths. After a certain period of time, those voids break down which, in turn, leads to the slip of upper layers and the so-called landslides forming on the surface. This situation imposes the necessity of basis and sealing rock mass reinforcement. To minimize the risk connected to geotechnical problems on the mining areas, there is a need to use engineering solutions which could improve soil bearing in a universal, economical and efficient way. This leads to the development of new cement slurry recipes used during geoengineering works, especially in the mining areas. Moreover, economic requirements are forcing engineers to use less expensive technical and technological solutions simultaneously maintaining strength properties. An example of such a solution is to use suitable additives to cement slurry which could reduce the total unit cost of the treatment.
Mine drainage and discharge of salt waters into water bodies belong to main environmental issues, which must be appropriately addressed by the underground coal mining industry. The large area of exploited and abandoned mine fields in the Upper Silesia Coal Basin, as well as the geological structure of the rock mass and its hydrogeological conditions require the draining and discharge of about 119 million m3/yr of mine waters. Increasing the depth of mining and the necessity of protection of mines against water hazard result in increased amounts of chlorides and sulphates in the mine waters, even by decreasing the total coal output and the number of mines. The majority of the salts are being discharged directly into rivers, partly under control of salt concentration, however from the point of the view of environment protection, the most favorable way of their utilization would be technologies allowing the bulk use of saline waters. Filling of underground voids represents a group of such methods, from which the filling of goaves (cavings) is the most effective. Due to large volume of voids resulting from the extraction of coal and taking the numerous limitations of this method into account, the potential capacity for filling reaches about 17.7 million m3/yr of cavings and unnecessary workings. Considering the limited availability of fly ash, which is the main component of slurries being in use for the filling of voids, the total volume of saline water and brines, which could be utilized, has been assessed as 3,5–6,5 million m3/yr
Coal ash produced from thermal power plants as a substitute for conventional construction material has increased considerably in recent years. In the past, studies on partial replacement of soil were carried out with a single type of ash. Because of the insufficient evidence, limited research has been initiated on the productive usage of Fly and Bottom Ashes. This paper aims to study the properties of these materials and investigate their efficacy in road construction. Laboratory investigations were conducted to assess chemical and physical properties and mechanical performance to evaluate both ash types in pavement construction. The rutting factor is calculated for various combinations of coal ash materials with the addition of polypropylene fiber as a reinforcement in increments of 0.1% of its total weight with an aspect ratio of 200. The analytical tool ANSYS is used to validate the service life, vertical strain and quality of reinforced ash materials.
The present study examines some durability aspects of ambient cured bottom ash geopolymer concrete (BA GPC) due to accelerated corrosion, sorptivity, and water absorption. The bottom ash geopolymer concrete was prepared with sodium based alkaline activators under ambient curing temperatures. The sodium hydroxide used concentration was 8M. The performance of BA GPC was compared with conventional concrete. The test results indicate that BA GPC developes a strong passive layer against chloride ion diffusion and provides better protection against corrosion. Both the initial and final rates of water absorption of BA GPC were about two times less than those of conventional concrete. The BA GPC significantly enhanced performance over equivalent grade conventional concrete (CC).
Preliminary lab-scale investigations were conducted on slagging abatement in biomass-firing by fuel mixing. Three agriculture biomass fuels and olive cake were used in the experiments. Polish lignites and bituminous coals were examined as anti-sintering additives. The effects of chlorine release, potassium retention and ash sintering were examined by heating samples of biomass fuels and additives in the muffle oven and, next, firing them in the laboratory down-fired furnace at the temperature in the range of 800-1150ºC. The obtained slag samples were analysed on: chlorine and potassium content, sintering tendency and crystalline components. Among the examined coals lignite from Turów mine and bituminous coal from Bolesław Śmiały mine appeared to be the most effective in potassium retention in aluminosilicate and chlorine release from slag. Possibly the major factor of these coals which reduced ash sintering was relatively high content of kaolinite
The paper presents the results of the mechanical, electrical, CCSEM and XRD measurements of hard coal, conducted in simulated conditions of sintering in atmospheres of O2/CO2,. The changes of the coal ash resistivity are correlated with the content of the oxides and with the sintering temperature determined by the mechanical test and Leitz method. The SEM-EDS analysis was conducted for deposits on the probe. The changes of the measured ash samples, observed during sintering process in O2/CO2 atmosphere, were discussed in the ash microstructure point of view.
One of the elements of the Polish Energy Policy program is the development of renewable energy, including energy from biomass combustion. In Poland, the Green Block was built at the Połaniec Power Station fired with 100% biomass fuel. This solution is conducive not only to obtaining energy but also to improving environmental protection. During the combustion of biomass in a fluidized bed boiler, about 50 thousand tons of fly ash per year being a source of nutrients for plants, for example potassium salts, phosphorus, calcium, boron compounds, etc. was derived. The subject of the research were three types of ashes from biomass combustion containing 80% dendromass and 20% agromass. Agromas was made of straw, dried material or sliced palm nuts. The physical characteristics and chemical composition of three basic fly ash samples are presented. Due to the high fineness and thus dusting during spreading, it was found that there is no possibility of the direct use of fly ash from biomass combustion as an alkalizing agent for acidic soils. The lowest bulk density was demonstrated by samples of fly ash originating from the combustion of biomass containing 20% straw as agromass, while the poorest in potassium and phosphorus were ash samples obtained from the combustion of biomass containing 20% agromass in the form of palm kernel slate. As additional components, mineral acids as well as inorganic compounds, including industrial waste, were used to correct the chemical composition and to mineral fertilizer granulation. The number of introduced components was related to the postulated composition of the produced fertilizer. Examples of mineral fertilizers obtained, both simple and multicomponent fertilizers, are presented.
Oxide fraction of industrial zinc ash from hot dip galvanizing was characterized in terms of composition and leaching behaviour in 10% sulfuric acid solution. Waste product contained about 68% Zn, 6% Cl, 3% Al, 1% Fe, 0.7% Si, 0.5% Pb and minor percentages of other metals (Mn, Cu, Ti etc.). It consisted mainly of zinc oxide contaminated with metallic zinc, zinc hydroxide chloride and silica. Dissolution of the metals from the material was determined as a function of solid to liquid ratio (50-150 kg/m3), temperature (20°C and 35°C) and agitation rate (300 and 900 rpm). The best results (50 g/dm3 Zn(II) at 78% zinc recovery) were obtained for 100 kg/m3 and the temperature of 20°C. Increase in the agitation rate had weak effect on the zinc yield. The final solutions were contaminated mainly by Fe(II, III) ions. Leaching of the material was an exothermic process with the reaction heat of about 800 kJ/kg.
Geopolymers are a new class of materials that can be synthesized using natural minerals, and waste materials. Among these substrates, the use of ﬂy ash is desirable as it involves the conversion of a copious waste material into a useful product. The aim of the research was geopolymers synthesis from coal ﬂy ash and biomass ash. Concentrated sodium hydroxide and sodium silicate solutions were used as activators in geopolymerisation reaction. The results show that both coal ﬂy ash and biomass ash can be utilized as source materials for the production of geopolymers. The surface morphology and chemical composition analysis were examined for the obtained geopolymers and ashes from coal and biomass combustion by SEM-EDS methods. It was found almost total disappearance of spherical forms of grains and reduction the porosity of structure for geopolymer based on ﬂy ash from coal combustion. While the structure of the geopolymer based ash from biomass combustion is more porous. The UV-VIS-NIR spectra were performed on the coal ﬂy ash, biomass ash and geopolymers. They showed that the obtained geopolymers possess optical and photocatalytic properties. The similarity of the geopolymer network and the zeolite framework in relation to ion exchange and accommodation of metal ions open questions on possibilities for the application of geopolymer materials as amorphous analogues of zeolite. The FT-IR spectra analyses were used on the geopolymers before and after metals sorption. It was found that geopolymer based on ash from biomass combustion has better sorption properties compared to geopolymer based on ash from coal combustion.
Due to the fact that the landfill deposition of municipal waste with the higher heating value (HHV) than 6 MJ/kg in Poland is prohibited, the application of waste derived fuels for energy production seems to be good option. There is a new combined-heat-and-power (CHP) plant in Zabrze, where varied solid fuels can be combusted. The formation of ashes originating from the combustion of alternative fuels causes a need to find ways for their practical application and demands the knowledge about their properties. Therefore, the present work is devoted to studying the co-combustion of solid recovered fuel (SRF) and coal, its impact on fly ash quality and the potential application of ashes to synthesis zeolites. The major objectives of this paper is to present the detail characteristics of ash generated during this process by using the advanced instrumental techniques (XRF, XRD, SEM, B ET, TGA). The co-combustion were carried out at 0.1 MWth fluidized bed combustor. The amount of SRF in fuel mixture was 1, 5, 10 and 20%, respectively. The focus is on the comparison the ashes depending on the fuel mixture composition. Generally, the ashes characterise high amounts of SiO2, Al2O3 and Fe2O3. It is well observed, that the chemical composition of ashes from co-combustion of blends reflects the amount of SRF addition. Considering the chemical composition of studied ashes, they can be utilize as a zeolites A. The main conclusions is that SRF can be successfully combusted with coal in CFB technology and the fly ashes obtained from coal + SRF fuel mixtures can be used to synthesis zeolites.
The article presents the results of the analysis of straw obtained from ripening wheat, which was subjected to four water soaking cycles in demineralized water. The soaking was carried out under laboratory conditions at 20°C. As a result, part of mineral matter, including a significant amount of alkaline sodium and potassium salts and substances containing sulfur and phosphorus, was washed out. The process of soaking has a great impact on the chemical composition of ash obtained from water-treated straw, which increased its acidity. The Na2O content in the analyzed ash has decreased by 78%, while the K2O content has decreased by 60%. In turn, the content of water-insoluble, acid-forming SiO2 has increased by 80%. As a consequence, a positive change in the values of indices, on the basis of which the tendency of straw to slagging and deposit formation during the combustion and gasification processes is assessed, has been observed. Already after the second water soaking cycle it became apparent, based on the AI alkali index, that the examined fuel should not cause difficulties resulting from the increased intensity of use of the boiler during the combustion process. Meanwhile, the value of the BAI bed agglomeration index was considered to be safe, indicating a low possibility of bed agglomeration during the combustion or fluidized bed gasification, after the third water soaking cycle. The third of the analyzed indices, the Fu fouling index, did not indicate any tendency to deposit formation during the combustion; however, four water soaking cycles reduced its initial value by 80%. The last of the analyzed indexes, the SR, slag viscosity index did not change its value during the experiment, which, both for the raw straw and after subsequent soaking cycles, indicated that the fuel should have a low tendency to accumulate slag during the combustion process.
This article presents the results of the study of changes in mineral and chemical composition of artificial aggregates consisting of coal shale (a hard coal mining waste) and fluidized ashes. Such an aggregate was used for road construction. After completion of the construction works but before making the road available for public use, significant deformation of the surface in the form of irregular buckling of the asphalt layer occurred. It was excluded that this resulted from mining damage, design errors or performance mistakes, among others. A study of the materials that had been incorporated in the construction layers was undertaken in order to find the component and the mechanism responsible for the buckling of the road surface. A comparison of the mineral and chemical composition of aggregate samples collected from the embankment where the road buckled with the reference sample and samples from places without deformations showed that the bumps in the road embankment consisted of minerals that were not initially present in the aggregate. Wastes produced as a result of high temperatures (slag and power plants ashes, metallurgical wastes) are not as stable in terms of chemical and phase composition in the hypergenic environment. As a result of the processes occurring in the road embankment, anhydrite, which is the primary component of fluidized ashes, was transformed into gypsum and ettringite. As a result of contact with water CaO (present in fluidized ashes) easily changed into calcium hydroxide. As the crystallization of these minerals is expansive, it resulted in the filling of pores and, in extreme cases, in a substantial increase in the volume of the aggregate and, consequently, in the deformation of the road surface.
This paper presents the results of research focused on the lowering of ash flow temperature at semianthracite coal from Donbas district by means of additive (calcite) dosing. Ash fusion temperatures were set for two coal samples (A, B) and for five various states (samples of ash without any additives, with 1%, with 3%, with 5% and with 7% of the additive) in total. The macroscopicphotographic method was used for identifying all specific temperatures. Obtained outputs prove that A type coal has a lower value of sphere temperature than B type coal in the whole scope of percentage representation of the additive. The flow temperature dropped in total from 1489 °C to 1280 °C, i.e. by 14% during the test of coal of type A with 7% of the additive; while it was near 10% for coal of type B (from 1450 °C to 1308 °C). Numerical simulations of the process showed that it is not effective to add an additive with a grain size lower than 280 μm by means of wastevapour burners.