Department of Material Structure and Properties
Institute of Rock Structure and Mechanics of the CAS

Services & Expertise International Cooperation Laboratory of Inorganic Materials
Basic Information Research Activities Most important results Projects

Phase transformations in fly ash-based solids

The phase transformations in fly ash-based solid bodies over 8 years were described. For experiments, bricks from the mixture of fly ash and quartz sand were industrially made and left outside. Subsequent mineralogical analyses of samples of various ages confirmed differences in phase compositions. It is suggested that the main role in the phase changes is played by the content of the roentgen-amorphous part of alumina-silicates because they can be transformed into a stable form of feldspar.

Publication: Perná, Ivana, Hanzlíček, Tomáš, Šupová, Monika, Novotná, Martina. Phase Transformations in Fly Ash-Based Solids. Minerals. 2020, 10(9), 804. ISSN 2075-163X DOI: 10.3390/min10090804


The surface of a solid sample containing fly ash from fluidised-bed combustion with different types of crystals: (a) general view, (b) surface with flake crystals, (c) surface with needle crystals

The creation of strong magnetic fields from neodymium magnets and their use in industrial practice

The results of the basic and applied research of strong magnetic fields and their use in industry obtained by Institute researchers over the last twenty years were summarised in the form of an extensive review that documented, inter alia, the use of developed and constructed magnetic separators and filters in the production lines of large industrial companies such as Lasselsberger, Laufen and Elektroporcelán a.s. and for research purposes at Czech and Slovak technical universities, e.g. the Technical Universities of Ostrava and Košice.

Publication: Straka P., Žežulka V. (2019). Linear structures of Nd-Fe-B magnets: Simulation, design and implementation in mineral processing –A review. Minerals Engineering 143 (2019) 105900. DOI: 10.1016/j.mineng.2019.105900


The industrial installation of a magnetic filter with Nd-Fe-B magnets for dual-stage magnetic filtration in a production line for the preparation of sanitary ceramic glazes (Laufen).

The synthesis and characterisation of geopolymers based on metakaolin and ash produced via the imperfect combustion of straw (ash with high ignition losses).

Ash produced via the imperfect combustion of straw was used as a filler in metakaolin-based geopolymers. It was found that geopolymer bonds are formed even following the addition of the ash, and that the addition of 33% by weight of ash significantly reduces the setting time of the mixture from 720 to 120 minutes; however, it was also determined that the compressive strength of the resulting material is adversely affected by the addition of the ash. The polyaromatic hydrocarbons (PAHs) contained in the ash as pollutants were found to be largely inhibited within the geopolymer structure.

Publication: Perná I., Šupová M., Hanzlíček T., Špaldoňová A.(2019). The Synthesis and Characterization of Geopolymers Based on Metakaolin and high LOI Straw Ash. Construction and building materiál 228,116765. DOI: 10.1016/j.conbuildmat.2019.116765


The use of ash produced via the imperfect combustion of straw: the incorporation of ash into the geopolymer matrix in the presence of alkalis reduced the solidification time, affected the compressive strength of the resulting material and inhibited pollutants.

Electro-optical glass for light modulators

Light modulators are used to process optical signals, while allowing for the control of the phase, frequency, amplitude and polarisation of the transmitted beam. Glass with a sufficiently high electro-optical coefficient is required for the construction of efficient optical modulators that operate in the visible and near-infrared region. Heavy metal oxide glass based on the PbO-Bi2O3-Ga2O3 ternary system is characterised by high optical sensitivity, and its thermal stability is enhanced via treatment with Ag2O and Sb2O. It was determined that such glass is permeable to infrared radiation up to 7.4 μm and that it has a high refractive index (up to 2.487 at the wavelength of light used at 473 nm), which also indicates its high ability to polarise light. The resulting electro-optical coefficient was determined at 7.47 - 7.77 × 1012m × V−2, which is high enough for the construction of an electro-optical modulator. This value can be further increased by Ag nanoparticles created via the reduction of Ag+ ions by Sb3+ ions.

Publication: Jílková K.,Míka M.,Kostka P.,Lahodný F.,Nekvindová P.,Jankovský O.,Bureš R.,Kavanová M. (2019). Electro-optic glass for light modulators. Journal of Non-Crystalline Solids518, 51–56. DOI: 10.1016/j.jnoncrysol.2019.05.014


The permeability of glass with the PbO-Bi2O3-Ga2O3 ternary system and treated with Ag2O and Sb2O in terms of infrared radiation.

Further important publications and outputs

Hujová M., Kloužek J., Cuthforth D.A., Lee SM., Miller M.D., McCarthy B.P., Hrma P., Kruger A.A., Pokorný R. (2019). Cold-cap formation from a slurry feed during nuclear waste vitrification. Ceramics International 45, 6405–6412. DOI: 10.1016/j.ceramint.2018.12.127

Appel C.J., Kloužek J., Nikhi J., Lee SM., Dixon D.R., Hrma P., Pokorný R., Schweiger M.J., Kruger A.A. (2019). Effect of sucrose on foaming and melting behavior of a low-activity waste melter feed. Journal of the American Ceramic Society 102, 7594–7605. DOI: 10.1111/jace.16675

Lee SM., Hrma P., Pokorný R., Kloužek J., Eaton W.C., Kruger A.A.(2019).Glass production rate in electric furnaces for radioactive waste vitrification. Journal of the American Ceramic Society 102,5828–5842. DOI: 10.1111/jace.16463

Hrma P., Kloužek J., Pokorný R., Lee S.M., Kruger A.A.(2019).Heat transfer from glass melt to cold cap.Gas evolution and foaming. Journal of the American Ceramic Society 102, 5853–5865. DOI: 10.1111/jace.16484

Lee SM., McCarthy B.P., Hrma P., Chun J., Pokorný R., Kloužek J., Kruger A.(2019).Viscosity of glass-forming melt at the bottom of high-level waste melter-feed cold caps: effects of temperature and incorporation of solid components. Journal of the American Ceramic Society. DOI: 10.1111/jace.16876

Pokorný R., Hrma P., Lee SM., Kloužek J., Choudhary M., Kruger A. (2019).Modeling batch melting: Roles of heat transfer and reaction kinetics. Journal of the American Ceramic Society. DOI: 10.1111/jace.16898

Kostka P., Ivanova Z.G., Nouadji M., Černošková E., Zavadil J.(2019).Er-doped antimonite Sb2O3-PbO-ZnO/ZnS glasses studied by low temperature photoluminescence spectroscopy. Journalof Alloys and Compounds780,866–872. DOI: 10.1016/j.jallcom.2018.11.361

Jebavá M., Hrbek L., Němec L.(2019).Energy distribution and melting efficiency in glass melting channel: Effect of heat losses, average melting temperature and melting kinetics. Journal of Non-Crystalline Solids521,119478. DOI: 10.1016/j.jnoncrysol.2019.119478

Lee SM., Hrma P., Pokorný R., Traverso J.J., Kloužek J., Schweiger M.J., Kruger A.A.(2019).Heat transfer from glass melt to cold cap: Effect of heating rate. International Journal of Applied Glass Science10,401–413. DOI: 10.1111/ijag.13104

Hrma P., Pokorný R., Lee S., Kruger A.A: Heat Transfer from Glass Melt to Cold Cap: Melting Rate Correlation Equation(2019). International Journal of Applied Glass Science10,143–150. DOI: 10.1111/ijag.12666

Bosák O., Castro A.,Labaš V., Trnovcová V., Kostka P., Calvez L., Le Coq D., Kubliha M.(2019).Influence of NaI Additions on the Electrical, Dielectric, and Transport Properties in the GeS2–Ga2S3–NaI Glass System. Russian Journal of Electrochemistry55,501–509. DOI: 10.1134/S1023193519060053

Further publications in ASEPu database

Patents:

Method and device for energy processing dried sewage sludge. An energetic method of recovery of digested, dewatered and dried sludge at the outlet of a wastewater treatment plant by the production of heating gas and a method of its connection to the gas management of the wastewater treatment plant were developed. The applicable sludge treatment product is also a soil fertilizer containing nutrients such as phosphorus, calcium and magnesium, important for supplementing nutrients to the soil system.

Glass melting furnace with conversion region to convert glass batch into glass melt. Glass melting furnace consists of conversion and homogenization regions. Conversion region has two batch chargers on both counter side walls. Glass and batch are heated by vertical bottom electrodes and by vertical oxy/gas burners placed in a crown of combustion space. The part of Joulean energy to the total supplied energy is at least 50%; the total supplied energy moves between 6 and 14 MW for melting of 3-7 kg of glass per second.

Glass melting furnace. Glass melting furnace with horizontal flow of melt contains conversion region and following homogenization region. The conversion region is heated by electrodes and/or gas burners and homogenization region is heated by electrodes or burners. Distribution of energy into both regions is set by two factors which allows to control a character of the glass melt flow.

Utility patent:

Němec L., Hrbek L., Jebavá M., Brada J. (2019). Schmelzraum eines kontinuierlichen Glass-schmelzofens und nach einem darin ausgeführtem Verfahrenerhaltene Glass-schmelze.Gebrauchsmusterschrift DE 20 2018 105 160 U1, 2019.02.14, Deutsches Patent-und Markenamt,München.