The article presents the results of research carried out using a water model of a refining ladle for the Fe-Si ferroalloys treatment. These studies were aimed at improving the efficiency of refining and homogenization of liquid Fe-Si ferroalloy in the refining ladle by using a new method of blowing gas through a system of nozzles installed at the bottom of the ladle. The obtained results allowed to determine the proper location of the plug at the bottom of the refining ladle and the possibility of using combined blowing. The tests were carried out for a refining ladle with a capacity of 3 m3 using a physical model on a linear scale of 1:3. The gas flow rate used in the model corresponded proportionally to the value previously used in industrial practice and amounted to 26.8 l/min. Experiments were performed for both combined blowing applications and through a purging plug at the bottom of the ladle. In the case of combined blowing, the volume of the gas stream was divided into two blowing sources (lance and purging plug). As a result of laboratory tests, one of the variants was selected and tested in industrial conditions. These studies confirmed the improvement in the efficiency of refining treatment of the FeSi alloy in terms of reducing the carbon and aluminum content in the alloy.x.

• Klíčová slova
• Ferroalloys, Ferrosilicon, Physical modelling, Refining gas, Steel, Water models,
• Publikační typ
• časopisecké články MeSH

Concern for the environment and rational management of resources requires the development of recoverable methods of obtaining metallic materials. This also applies to the production of aluminium and its alloys. The quality requirements of the market drive aluminium producers to use effective refining methods, and one of the most commonly used is blowing an inert gas into liquid aluminium via a rotating impeller. The efficiency and cost of this treatment depends largely on the application of the correct ratios between the basic parameters of the process, which are the flow rate of the inert gas, the speed of the rotor and the duration of the process. Determining these ratios in production conditions is expensive and difficult. This article presents the results of research aimed at determining the optimal ratio of the inert gas flow rate to the rotary impeller speed, using physical modeling techniques for the rotor as used in industrial conditions. The tests were carried out for rotary impeller speeds from 150 to 550 rpm and gas flow rates of 12, 17 and 22 dm3/min. The research was carried out on a 1:1 scale physical model, and the results, in the form of visualization of the degree of gas-bubble dispersion, were assessed on the basis of the five typical dispersion patterns. The removal of oxygen from water was carried out analogously to the process of removing hydrogen from aluminium. The curves of the rate of oxygen removal from the model liquid were determined, showing the course of oxygen reduction during refining with the same inert gas flows and rotor speeds mentioned above.

• Klíčová slova
• aluminium, physical modeling, refining, rotary impeller,
• Publikační typ
• časopisecké články MeSH

The paper presents the results of tests carried out during the refining of the AlSi9Cu3(Fe) alloy in industrial conditions at the FDU stand. In the tests, three different rotors made of classical graphite, fine-grained graphite and classical graphite with SiC spraying were tested for the degree of wear. A series of tests was conducted for five cases-0% to 100% of consumption every 25%-corresponding to the cycles of the refining process. The number of cycles corresponding to 100% wear of each rotor was determined as 1112. The results of the rotor wear profile for all types of graphite after the assumed cycles are presented. Comparison of CAD models of new rotors and 3D scans of rotors in the final stage of operation revealed material losses during operational tests. The study assessed the efficiency of the rotor in terms of its service life as well as work efficiency. It was estimated on the basis of the calculated values of the Dichte Index (DI) and the density of the samples solidified in the vacuum. The structure of samples before and after refining at various stages of rotor wear is also presented, and the results are discussed.

• Klíčová slova
• aluminum refining, graphite wear, rotary impeller, wear testing,
• Publikační typ
• časopisecké články MeSH

The article focuses on the issue of improving the efficiency of a Foundry Degassing Unit (FDU) via operational testing of aluminium alloys during casting at MOTOR JIKOV Slévárna a.s.. As part of the research, the efficiency of the refining process in the FDU was assessed. The main emphasis was placed on determining the moment of the greatest decrease in the hydrogen content in the melt and whether it is possible to shorten the refining cycle. The values of the Dichte Index were determined, on the basis of which the degassing curve was plotted and the progress of the melt degassing was assessed. To ensure the required quality of castings, the maximum allowable value of the Dichte Index ranged from 3 to 4%. During the process, the temperature drop during the refining cycle was also determined. The total temperature drop from pouring the melt into the ladle to the end of refining ranged from 26 to 32 °C, which is within the acceptable limits of the foundry. Based on the knowledge resulting from the operational experiments, recommendations were formulated to optimize the refining technology at the FDU for the MOTOR JIKOV Slévárna a.s. foundry.

• Publikační typ
• časopisecké články MeSH

3-MCPD esters are contaminants that can form during refining of vegetable oils in the deodorization step. It was experimentally shown that their content in the vegetable oil depends on the acid value of the vegetable oil and the chloride content. 3-MCPD esters form approximately 2-5 times faster from diacylglycerols than from monoacylglycerols. It has been proved that the higher fatty acids content in the oil caused higher 3-MCPD esters content in the deodorization step. Neutralization of free fatty acids in the vegetable oil before the deodorization step by alkaline carbonates or hydrogen carbonates can completely suppress the formation of 3-MCPD esters. Potassium salts are more effective than sodium salts.

• Klíčová slova
• 2-Diol, 2-Dipalmitate, 3-CPD esters, 3-Chloropropane-1, 3-MCPD esters, Deodorization, Palm oil, Refining,
• MeSH
• alfa-chlorhydrin analýza   chemická syntéza   MeSH
• chloridy analýza   MeSH
• diglyceridy chemie   MeSH
• estery MeSH
• kyseliny mastné neesterifikované chemie   MeSH
• manipulace s potravinami metody   MeSH
• mastné kyseliny analýza   MeSH
• odoranty MeSH
• oleje rostlin chemie   MeSH
• Publikační typ
• časopisecké články MeSH
• Názvy látek
• alfa-chlorhydrin MeSH
• chloridy MeSH
• diglyceridy MeSH
• estery MeSH
• kyseliny mastné neesterifikované MeSH
• mastné kyseliny MeSH
• oleje rostlin MeSH

Elephants are on the verge of extinction due to extensive poaching to obtain ivory and illegal income. According to international law, the trade in ivory of African elephants is outlawed, with a few exceptions, as for example in European Union for antique ivory obtained before 1947. There is basically only one physical method for determining the age of ivory and that is radiocarbon dating. The method uses artificially temporarily enhanced 14C content in the atmosphere to date relevant samples with high resolution. Since this advantage is slowly fading, the question arises of how to fill in the loss of the resolution. One possibility is exploiting the chronology of ivory. This work studies a whole elephant tusk and uses radiocarbon dating of samples obtained longitudinally and transversely from along the tusk to analyse the growth rate.

• MeSH
• obchod MeSH
• radioaktivní datování * MeSH
• sloni * MeSH
• zachování přírodních zdrojů MeSH
• zločin MeSH
• zvířata MeSH
• Check Tag
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH

Physical modelling is successfully used to understand mechanisms involved in the aluminium refining process by injecting inert gas into the liquid metal through rotors. Two types of industrial impellers, which are extremely different in construction, were tested in the research. The aim of the research was to determine the effectiveness of their operation depending on their degree of wear. This type of research has not been tested on water models so far. During the process, the parameters were changed, such as the gas flow rate from 13 to 19 L/min, the rotor speed from 325 to 400 rpm and the height of the rotor from the bottom of the refining reactor. Tests were carried out for new and worn rotors. Oxygen removal rate curves were prepared on the basis of tests determining changes in oxygen content in the model liquid as a function of time for changing rotor speed values. It was found that the efficiency of hydrogen removal from the model liquid was higher when worn impellers were used in the model. In order to verify results of model tests, a metallographic analysis of samples obtained in industrial conditions and using the analysed process parameters was carried out.

• Publikační typ
• časopisecké články MeSH

Our study compares short-range order parameters refined from the diffuse scattering in single-crystal X-ray and single-crystal electron diffraction data. Nb0.84CoSb was chosen as a reference material. The correlations between neighbouring vacancies and the displacements of Sb and Co atoms were refined from the diffuse scattering using a Monte Carlo refinement in DISCUS. The difference between the Sb and Co displacements refined from the diffuse scattering and the Sb and Co displacements refined from the Bragg reflections in single-crystal X-ray diffraction data is 0.012 (7) Å for the refinement on diffuse scattering in single-crystal X-ray diffraction data and 0.03 (2) Å for the refinement on the diffuse scattering in single-crystal electron diffraction data. As electron diffraction requires much smaller crystals than X-ray diffraction, this opens up the possibility of refining short-range order parameters in many technologically relevant materials for which no crystals large enough for single-crystal X-ray diffraction are available.

• Klíčová slova
• 3D difference pair distribution functions, 3D electron diffraction, 3D-ΔPDF, 3DED, single-crystal diffuse scattering,
• Publikační typ
• časopisecké články MeSH

OBJECTIVES: To provide a contemporary statement on focal therapy (FT) for localised prostate cancer (PCa) from an international and diverse group of physicians treating localised PCa, with the aim of overcoming the limitations of previous consensus statements, which were restricted to early adopters, and to offer direction regarding the various aspects of FT application that are currently not well defined. MATERIALS AND METHODS: The FocAL therapy CONsensus (FALCON) project began with a 154-item online survey, developed following a steering committee discussion and literature search. Invitations to participate were extended to a large, diverse group of professionals experienced in PCa management. From 2022 to 2023, a Delphi consensus study consisting of three online rounds was conducted using the Modified Delphi method. A 1-9 Likert scale was used for the survey, which was followed by an in-person expert meeting. The threshold for achieving consensus was set at 70% agreement/disagreement. Six main aspects of FT were covered: (i) patient selection; (ii) energy source selection; (iii) treatment approach; (iv) treatment evaluation and follow-up; (v) treatment cost and accessibility; and (vi) future perspectives. RESULTS: Of 246 initial participants, 148 (60%) completed all three rounds. Based on participant feedback, 27 new statements were added in the second round, and 33 questions related to personal expertise, for which consensus was not necessary, were excluded. After the third and final round, consensus had not been reached for 69 items. These items were discussed at the in-person meeting, resulting in a consensus of 57 additional items. Consensus was finally not reached on 12 items. Given the volume of data, the voting outcomes are summarised in this article, with a detailed breakdown presented in the form of figures and tables. CONCLUSIONS: The FALCON project delivered a significant consensus on the approach to FT for localised PCa. Additionally, it highlighted gaps in our knowledge that may provide guidance for future research.

• Klíčová slova
• Delphi study, ablation techniques, consensus, energy source selection, patient selection, prostate cancer, treatment evaluation,
• Publikační typ
• časopisecké články MeSH

Fly ash microspheres, also called cenospheres, have many valuable properties that allow them to be widely used. Some of its most important properties are its mechanical and thermal strength as well as its chemical stability. These features constitute an important commercial parameter. Refining processes aim to select the highest quality product from raw materials that meets the expectations of recipients. Generally, preparing a final product involves selecting the appropriate sequence and parameters of the grain separation process. However, the key to the optimal selection of these parameters is knowledge of the specificity of the processed raw material. Microspheres are materials that are created spontaneously, uncontrolled, and without the possibility of intentionally influencing their properties. Therefore, due to the potential directions of microsphere use, it is justified to study the relationship between density, grain size, and mechanical strength. Understanding these relationships in microspheres from various sources is particularly important at the stage of planning refining processes. This paper presents the results of research on microspheres from two different sources. The tested raw materials (microspheres) are subjected to densiometric and grain analysis. Also, mechanical strength was determined for the separated density fractions and grain classes. The test results did not show significant correlations between the tested features of the microspheres. In the case of both raw materials, the highest density was observed in the smallest grain classes, and the highest mechanical strength was determined for microspheres with grain sizes in the range of 75-100 µm. For this grain size range, the value of mechanical strength is 26 for raw Material 1 and 38 for raw Material 2. The shares of this grain fraction in the microsphere stream are 11.2% and 16%, respectively. An important difference that may significantly affect the efficiency of the refining process is the method of distribution of the primary falling parts, which affects the mechanical strength of the tested raw materials.

• Klíčová slova
• cenospheres, fly ash, microsphere, mineral resources, mineral waste recovery,
• Publikační typ
• časopisecké články MeSH