Alexander Karamanov

Alexander Karamanov
Bulgarian Academy of Sciences | BAS · Rostislav Kaishev Institute of Physical Chemistry

Prof. Dr.

About

87
Publications
13,412
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2,372
Citations
Additional affiliations
January 2007 - present
Bulgarian Academy of Sciences
January 1997 - December 2006

Publications

Publications (87)
Article
Full-text available
In the present study, thermal properties of geopolymer paste, based on fayalite waste from copper producing plants and metakaolin, were analyzed. The used activator solution was a mixture of sodium water glass, potassium hydroxide and water with the following molar ratio: SiO2/M2O = 1.08, H2O/M2O = 15.0 and K2O/Na2O = 1.75. High strength geopolymer...
Article
Full-text available
The materials used for the synthesis of parent glass are 70% wt. metallurgical slag and 30% wt. industrial quartz sand. The initial batch is melted at and then quenched in water. The resulting glass frit is milled bellow 75 microns and pressed 1400 °C into “green” samples. In a next stage, they are heat treated at different temperatures with variou...
Preprint
The Sari\c{c}i\c{c}ek howardite meteorite shower consisting of 343 documented stones occurred on 2 September 2015 in Turkey and is the first documented howardite fall. Cosmogenic isotopes show that Sari\c{c}i\c{c}ek experienced a complex cosmic ray exposure history, exposed during ~12-14 Ma in a regolith near the surface of a parent asteroid, and t...
Article
Full-text available
Ceramics, based on 60 wt% of municipal incinerator bottom ashes (MIBA) and 40 wt% of industrial clays, were prepared by using two fractions of pre-treated ashes (above and under 2 mm) and three different industrial clays. The obtained six compositions with amounts of CaO from 12 to 14 wt%, with SiO2/Al2O3 ratio ranging from 3.5 to 1.6 and with Al2O...
Article
Sintering, crystallization and foaming of nano glass powders with composition La2O3•SrO•5B2O3 were studied by hot stage microscopy (HSM) and simultaneous thermal analysis (DTA-TG) under non-isothermal regime at 10°C/min and by optical contactless dilatometer under isothermal conditions at 700 °C up to 10 hours for different times. After the thermal...
Article
The possibilities for the production of self-glazed sintered glass-ceramics or/and glass-ceramic foams using metallurgical slag are discussed. The effect of CaF2 addition on the glass melting, the densification and the foaming is also studied. The sintering and the bloating trends are evaluated by hot stage microscopy and the phase formation is est...
Article
In Italy, the production of bottom ash from waste incineration was estimated as 1.6 million tons/year, corresponding to 30% of the total input waste. The bottom ash is mainly formed by SiO2, Al2O3, CaO, Na2O and low amount of heavy metals, therefore it cannot be considered a ‘non-hazardous’ waste. In this context, the aim of this work was to determ...
Chapter
Full-text available
The subsequent synthesis of sintered self-glazed glass-ceramics and/or glass-ceramic foams using metallurgical slag is the topic under discussion. The observed intensive sample expansion can be considered as an autocatalytic process related to the oxygen release due to thermal reduction of Fe2O3 and MnO2 present in the slag. The sintering of the sa...
Article
Full-text available
The Sariçiçek howardite meteorite shower consisting of 343 documented stones occurred on September 2, 2015 in Turkey and is the first documented howardite fall. Cosmogenic isotopes show that Sariçiçek experienced a complex cosmic‐ray exposure history, exposed during ~12–14 Ma in a regolith near the surface of a parent asteroid, and that an ~1 m siz...
Article
The peculiarities of sinter-crystallization of La2O3·SrO·5B2O3 fine glass powder (below 1 μm) are investigated and discussed. The sintering was studied by contactless optical dilatometry and porosity measurements. The crystallization process was evaluated by differential scanning calorimetry (DSC) and the crystalline phase formation was analyzed by...
Article
The main objective of this work was to study the sintering process and technological properties of new fired bricks based on high amount of post-treated municipal solid waste incinerator bottom ash and refractory clay. In addition, the effect of the minor addition of flux (Na 2 CO 3 ) or reinforce (corundum) was also highlighted. Several methods we...
Article
Preliminary results on the production of new ceramic bricks by an innovative microwave-assisted sintering process employing MSWI bottom ashes are reported. Microwave heating technique was compared with a conventional thermal treatment with the aims to: (1) study the influence of heat treatment method on the crystallization behavior and on the micro...
Research
Full-text available
Abstract. Glass-ceramics are polycrystalline materials, containing amorphous and crystal phases and obtained by controlled crystallization of glasses with suitable compositions. The parent batch is melted, the melt is formed and thus prepared samples partially crystallize at secondary heat-treatment. The crystallization process can be controlled by...
Article
Hazardous electro-furnace slag (EFS), dust (D) and converter slag (CS) from ferronickel smelting plant were mixed with glass cullet and vitrified. The optimal heat-treatment regime for transformation of obtained glass into glass-ceramic was evaluated using fast alternative methods: the nucleation step was estimated by DTA analysis, while the crysta...
Article
Hazardous electro-furnace slag (EFS), dust (D) and converter slag (CS) from ferronickel smelting plant were mixed with glass cullet and vitrified. The optimal heat-treatment regime for transformation of obtained glass into glass–ceramic was evaluated using fast alternative methods: the nucleation step was estimated by DTA analysis, while the crysta...
Article
Full-text available
A glass, based on Electric Arc Furnace Slag (EAFS), is studied to produce a glass-ceramic with bulk crystallization. The main kinetics parameters are investigated by non-isothermal DTA, the formed crystal phases are evaluated with the application of XRD, while the microstructure is observed by SEM. The variations of density and porosity accompanyin...
Article
The aim of present article is to analyze experimental results on the non-isothermal kinetics of crystallization in dependence of minor composition changes. We investigate the role of network formers (Al 2 O 3) and network modifiers (Na 2 O), respectively, on the kinetics of overall crystallization of three glasses, forming about 60% diopside (CaO.M...
Conference Paper
Full-text available
This paper is concerned with environmental effects of the vitrification process of solid metallurgical waste (filter dust, FD, slag from electro-furnace, SEF and slag from converter, SC) from ferronickel production industry. Chemical and mineralogical characterization of the waste materials was done. The waste mixture (FD : SEF : SC = 1 : 10 : 1) c...
Article
Full-text available
Results about the vitrification of several hazardous iron-rich industrial wastes (from productions of Zn and Cu metals, as well as EAFD and MSWA) and the usage of obtained glasses for synthesise of sintered glass-ceramics are summarises. It is shown that the appropriated method of sinter-crystallization mainly depends on the crystallization trend o...
Conference Paper
Two new ceramic tile compositions based on 60 wt% secondary raw material (SRM) derived from pre-treated municipal solid waste incinerator bottom ashes and 40 wt% refractory clay were studied. The thermal and densification behaviours of the ceramic batches were evaluated by DTA/TG and dilatometric techniques, respectively. Sinterability was evaluate...
Conference Paper
Two new ceramic tile compositions based on 60 wt% secondary raw material (SRM) derived from pre-treated municipal solid waste incinerator bottom ashes and 40 wt% refractory clay were studied. The thermal and densification behaviours of the ceramic batches were evaluated by DTA/TG and dilatometric techniques, respectively. Sinterability was evaluate...
Conference Paper
Two new ceramic tile compositions based on 60 wt% secondary raw material (SRM) derived from pre-treated municipal solid waste incinerator bottom ashes and 40 wt% refractory clay were studied. The thermal and densification behaviours of the ceramic batches were evaluated by DTA/TG and dilatometric techniques, respectively. Sinterability was evaluate...
Conference Paper
Full-text available
Two new ceramic tile compositions based on 60 wt% secondary raw material (SRM) derived from pre-treated municipal solid waste incinerator bottom ashes and 40 wt% refractory clay were studied. The thermal and densification behaviours of the ceramic batches were evaluated by DTA/TG and dilatometric techniques, respectively. Sinterability was evaluate...
Conference Paper
Full-text available
Two new ceramic tile compositions based on 60 wt% secondary raw material (SRM) derived from pre-treated municipal solid waste incinerator bottom ashes and 40 wt% refractory clay were studied. The thermal and densification behaviours of the ceramic batches were evaluated by DTA/TG and dilatometric techniques, respectively. Sinterability was evaluate...
Article
Full-text available
In the present chapter, we describe results of experimental investigations and theo-retical analysis of phase selection and nucleation of pores in small samples of under-cooled diopside liquid when it is enclosed by a solid crystalline surface layer. The formation of the surface crystalline layer starts with nucleation and growth of highly dense di...
Conference Paper
Full-text available
ABSTRACT. New building ceramics, obtained by sintering at 1150-1250oC of huge amounts of Blast Furnace Slag or bottom ashes from Municipal Solid Waste Incinerator (MSWA) mixed with kaolin, are characterised. The phase compositions and the amounts of formed crystal and amorphous phases are estimated by XRD analysis. The structures of the final sampl...
Article
Full-text available
We focus our attention on Monte Carlo simulations of crystallization, which is one of the most important processes occurring in nature and technology of materials. Special attention is paid to the crystallization shrinkage and its consequences onto the growth of the new crystalline phase. We show that crystallization shrinkage stops after reaching...
Article
A new possibility for measurements of glass transition point, fictive temperature and activation energy of viscous flow in the glass transition range is shown by using a contactless horizontal optical dilatometer and pressed powder samples. The results are compared with ones, obtained with bulk samples and traditional differential contact dilatomet...
Article
Full-text available
New ceramics based on 60 wt% of alternative raw material derived from post-treated municipal solid waste incinerator bottom ashes and 40 wt% of refractory clay were studied. The chemical analysis of the compositions was evaluated by ICP. The thermal and densification behavior of the ceramic batches were evaluated by DTA-TG and dilatometry technique...
Article
The influence of grain size on the surface crystallization kinetics is investigated by non-isothermal Differential Thermal Analysis and Scanning Electron Microscopy. For this purpose, different powder fractions of a model glass forming diopside via surface crystallization and crystallization induced porosity, are used. The activation energy of crys...
Conference Paper
Full-text available
The production of building materials is still based mainly on the traditional system clay-quartz-feldspar. More scientific studies are related to the substitution of conventional raw materials by other natural resources or industrial waste. In this way it has developed a research to realize innovative ceramics for floor/wall covering without tradit...
Article
Three new ceramic batches with no traditional fluxes and 30, 50 and 70 wt.% blast furnace slag were studied. The processes of phase formation and densification were estimated in non-isothermal conditions by differential thermal analysis and dilatometry, respectively. After that the degrees of sintering, obtained after heat-treatment at different te...
Article
The sinter-crystallization ability of two glasses obtained by post-treated bottom ash of municipal solid waste incinerator (MSWI) at two particle size (coarse and fine) was investigated. The phase formation was estimated by DTA and XRD, while the sintering process was evaluated by optical dilatometry, linear shrinkage and water absorption. The poro...
Article
a b s t r a c t In glass–ceramics, the density difference between the new, semi-crystalline system, and the ambient phase requires a deformation of the grains. However, the first stage of surface induced crystallization is the creation of rigid shell, opposing the shrinkage. Therefore, an important stress appears inside the grain. If the average de...
Article
Alkaline basaltic tuffs, from Southern Turkey were characterized and employed to obtain ceramic and glass–ceramic materials by combined sintering and crystallization process. The chemical and mineralogical compositions were analyzed by X-ray fluorescence spectrometry and X-ray diffraction analyses, respectively. The phase formation and the sinterin...
Article
Full-text available
Preliminary results of an investigation into the possible use of glass-ceramic frits from fly ash and glass cullet in terracotta (stoneware) tile manufacture are reported. Two new ceramics were studied and compared with a plant composition, containing 45 wt.% sodium feldspar. In the first ceramic batch 20% of the feldspar was substituted by frits a...
Article
The possibility to obtain sintered material from alkaline basaltic tuffs is demonstrated. The parent rock was milled for 10–15 min, the resulting powder was pressed at 100 MPa and the obtained samples were heat-treated in the range of 1000–1140 °C. The sintering behaviour and the phase formation were studied by pycnometry, dilatometry, DTA, XRD and...
Article
Full-text available
The present paper discusses sintered glass-ceramics with attractive appearance, which are obtained by vitrification of hazardous industrial wastes. The chemical durability of parent wastes and resulting glasses was characterised by toxic characteristics leaching procedure (TCLP). The crystallisation behaviour was evaluated by DTA and XRD, while the...
Article
A diopside (CaO·MgO·2SiO2) and wollastonite (CaO·SiO2) glass-ceramics, forming ∼60% crystal phase and ∼40% albite-like (Na2O·Al2O3·6SiO2) residual glass were studied. Two other diopside glass-ceramics with higher Na2O and Al2O3 content were also investigated.The phase formation was estimated by DTA, XRD and pycnometry, while the densification proce...
Article
Vitrification by melting is being proposed as a convenient method to solidify different kinds of silicate and other oxide-based inorganic wastes. Incinerator bottom and fly ashes have been mixed with glass cullet, feldspar and clay by-products as melting fluxing agents. Washing, drying, and grinding pre-treatments followed by melting at 1450 °C lea...
Conference Paper
Full-text available
Sintered glass-ceramics, forming between 30 and 60 wt % diopside crystal phase and albite-like residual glasses were studied together with a wollastonite–albite composition, forming ~ 60% wollastonite. The crystallization and sintering were estimated by DTA and dilatometry, respectively, while surface and " bulk " structures of the final samples we...
Article
Full-text available
The possibility to obtain a cheap ceramic material based on 50 wt % basaltic tuffs and 50 wt % industrial clays was studied. The tuffs were characterized by optical microscopy, X-ray diffraction and differential thermal analysis. It was shown that this material is appropriate for the ceramic industry: it is easy for milling and is characterized by...
Article
The possibility to obtain a cheap ceramic material based on 50 wt % basaltic tuffs and 50 wt % industrial clays was studied. The tuffs were characterized by optical microscopy, X-ray diffraction and differential thermal analysis. It was shown that this material is appropriate for the ceramic industry: it is easy for milling and is characterized by...
Article
The vitrification of an hazardous iron-rich waste (W), arising from slag flotation of copper production, was studied. Two glasses, containing 30wt% W were melted for 30min at 1400 degrees C. The first batch, labeled WSZ, was obtained by mixing W, blast furnace slag (S) and zeolite tuff (Z), whereas the second, labeled WG, was prepared by mixing W,...
Article
Glass-ceramic materials, obtained by sinter-crystallization of melted alkaline-olivine basaltic tuffs, were investigated. The kinetics of bulk crystallization was evaluated by differential thermal analysis (DTA) at different heating rates. The phase formation and the sintering behavior of glass powders (<75 lm) were studied in air and in nitrogen a...
Article
The effect of the addition of porcelain fired scraps on the sintering, phase composition and properties of a hard porcelain was studied. Two ceramics were compared: a commercial triaxial porcelain labelled C-0 and one, where 15% of the mass of C-0 was substituted by scraps yielding a composition labelled C-15. The sintering was evaluated by the lin...
Article
A glass ceramic composite was obtained by sinter-crystallisation of vitrified municipal solid waste bottom ashes with the addition of various percentages of alumina waste. The sintering was investigated by differential dilatometry and the crystallisation of the glass particles by differential thermal analysis. The crystalline phases produced by the...
Article
The sinter-crystallisation was investigated in three model glasses (G1, G2 and G3) belonging to the diopside–albite system and forming between 30 and 60% diopside, respectively. The effect of bulk crystallisation on the sintering was studied by the addition of 0.7 wt.% Cr2O3 as nucleating agent to the G2 glass.The degree of sintering was evaluated...
Article
The formation of intragranular pores, induced by diopside crystallization in diopside–albite glasses, was highlighted in a previous study and here confirmed by SEM observation. The sinter-crystallization kinetics of four glass compositions, labelled G1, G2, G3 and G2-Cr, characterized by the formation of induced crystallisation porosity, PCR, was i...
Article
The sintering behaviour of a glass obtained by Municipal Solid Waste Incinerator (MSWI) bottom ash (WG) was investigated and compared with a Na 2 O–MgO–CaO–SiO 2 composition (CG). The sintering activation energy, E sin , and the energy of viscous flow, E , were evaluated by dilatomeric measurements at different heating rates. The formation of cryst...
Article
A series of sintered glass-ceramics belonging to the system diopside–albite, forming by surface crystallization 30, 50 and 65% diopside, was investigated. In order to study the effect of bulk crystallization on the sintering a 0.7% of Cr 2 O 3 as nucleation agent was added in one of the compositions. The crystallization was evaluated by DTA and den...
Article
In the present study, the sinter-crystallization behavior of a glass from municipal solid waste incineration ashes was investigated. The crystallization kinetics were estimated by DTA at different heating rates and the formed crystalline phases were evaluated by XRD. The sintering was studied at different heating rates and at different holding temp...
Article
Iron-rich glass-ceramics were obtained by the sintering of two glass powders, labeled G1 and G2, at heating rates of 5° and 20°C/min followed by an isothermal step in the 850°–1050°C temperature interval. The sintering process was evaluated by the linear shrinkage; the closed porosity was estimated by density measurements; the structure and the mor...
Article
The sintering and the crystallization of two iron-rich glass compositions (45–75-μm powder fractions) were studied in air and nitrogen atmospheres. The phase formation was evaluated by differential thermal analysis, while the densification, by dilatometry; the crystalline phases were identified by X-ray diffraction and the structure observed by sca...
Article
Full-text available
Glass-ceramics produced from industrial wastes have an appearance inferior to the natural stones or traditional tiling ceramics. By using the technology of sinter-crystallization of glass frit, introduced by Japanese "Neoparies" glass-ceramic, the appearance may be considerably improved. The present work summarises the results of glass-ceramics fro...
Article
A composition obtained by mixing MSW ashes with sand and glass cullet was melted at 1500 C and quenched in water. The obtained frit was sieved and separated in different fractions: L (large, 2–5 mm), I (intermediate, 1–2 mm) and S (small, < 1 mm). The sintering of the glass particles, carried out in an alumina mould, occurred in the 700–950 C range...
Article
A glass composition, made by mixing 70% of MSW ashes and 30% of waste from feldspar production, was studied. The batch was melted at 1350 °C and the melt was quenched in water. The chemical stability of the glass was investigated by TCLP leaching test. DTA experiment, at 10 °C/min heating rate in the 20–1200 °C range, showed that the glass has a hi...
Article
Electric arc furnace baghouse dust (EAFD), a waste by-product of the steelmaking process, contains the elements that are volatilized from the charge during the melting (Cr, Pb, Zn, Cu and Cd). The results of leaching tests show that the concentration of these elements exceeds the regulatory limits. Consequently, EAFD cannot be disposed of in ordina...
Article
Full-text available
Viscosity-temperature (V-T) curves for two iron rich glass compositions, named G1 and G2, made by various industrial wastes were obtained by using a dilatometry and rotational viscosimeter. The experimental V-T curves are compared with the theoretically estimated values by the Gehlholff-Thomass and Bottinga-Weill models. Investigated compositions s...
Article
Full-text available
The glass transformation temperature, Tg, of an iron rich glass, made up of hazardous industrial wastes, and of the corresponding glass ceramics with different percentages of crystal phase was investigated by differential dilatometry, differential thermal analysis (DTA) and density measurements. The Tg values, evaluated by different methods, are si...
Article
The influence of the Fe3+/Fe2+ ratio on the crystallization of iron-rich glasses was investigated in this study. The glass batches were made from two hazardous industrial wastes: mud (goethite and jarosite) originating from the zinc hydrometallurgical process and electric arc furnace dust (EAFD). Glass compositions were prepared by adding different...
Article
In this study, results of the crystallization of iron-rich glasses are summarized. Thermogravimetry (TG)–differential thermal analysis (DTA) were utilized to explain the phase formations and the surface oxidation of FeO to yield Fe2O3. The crystal phases fraction was evaluated utilizing X-ray diffraction analysis (XRD). Low angle XRD technique was...
Article
The vitrification of zinc-hydrometallurgy wastes, electric arc furnace dust (EAFD), drainage mud, and granite mud was shown to immobilize the hazardous components in these wastes. Batch compositions were prepared by mixing the wastes with glass-cullet and sand to force the final glass composition into the glass forming region of the SiO2-Fe2O3-(CaO...
Article
In the present work, the in¯uence of the nucleation time-lag on the non-isothermal glass crystallization is discussed. Di€erential thermal analysis (DTA) results of an iron-rich glass nucleated by Cr 2 O 3 were obtained at di€erent heating rates. The activation energy of crystallization, E c , and the Avrami parameter, m, estimated by Kissinger's a...
Article
The influence of the Fe 3 /Fe 2 ratio on the crystallization of iron-rich glasses was investigated in this study. The glass batches were made from two hazardous industrial wastes: mud (goethite and jarosite) originating from the zinc hydro-metallurgical process and electric arc furnace dust (EAFD). Glass compositions were prepared by adding differe...