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Dynamic mills
Pokluda, Petr ; Frühbauer, Jiří (referee) ; Malášek, Jiří (advisor)
This bachelor's thesis focuses on dynamic mills, i.e., devices designed for crushing materials. It contains a theoretical part discussing their classification, construction, principles of operation, and areas of application. The theoretical part is followed by a research section describing global manufacturers of dynamic mills and the specifications of the machines they offer. Subsequently, the practical section presents diagrams that integrate the entire process of selecting a mill from the customer's perspective. The final part of the thesis is devoted to the simulation of grinding. It describes the essence of the specific software's functionality and the practical implementation of the simulation on a particular machine.
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Monitoring the effect of sample treatment in determining selected properties of biofuel
Štenclová, Kristýna ; Lachman, Jakub (referee) ; Lisá, Hana (advisor)
Diploma thesis is focused on the treatment of biofuel prior to combustion and effect of this treatment on the biofuel characteristics. The first part is a review of literature encompassing characteristics of fuel, preparation of samples, methods of analysis of individual characteristics and a presentation of various types of mills. The second part of thesis is experimental. It is an analysis of sample characteristics under various mill settings with regard to the temperature in the mill during grinding.
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The influence of grinding on the limestone properties
Pavlík, Tomáš ; Bednárek, Jan (referee) ; Šiler, Pavel (advisor)
This bachelor thesis deals with dry limestone grinding in the vibratory mill and ball mill. Three different limestone samples were used for milling. Samples were ground in the mills without the addition of surfactants. Several methods of grinding were performed in the vibratory mill. At first, the same weight of limestone samples was ground for different grinding time without any interruption except for one case of grinding with breaks for cooling off the grinding tablet. Another method was grinding of different weights of the same sample. The last one used the same weight of different samples. In the ball mill, sample of one type of limestone was ground for various milling time. The particle size, shape of particles, phase composition and crystallite size were studied for the ground samples. Sieve analysis, laser diffraction analysis, scanning electron microscopy, powder X-ray diffraction analysis and X-ray fluorescence analysis were used to determine these properties. For each mill, the amount of energy consumed for limestone grinding was calculated.
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Effect of sample treatment on biofuel characteristics
Zlevorová, Tereza ; Lachman, Jakub (referee) ; Lisá, Hana (advisor)
The subject of this bachelor thesis is experimental solution of the problem focused on the effect of sample treatment on bioful characteristics. The theoretical introduction includes biofuel classification, explanation of each biofuels‘ trait and description of methods used to their determination. It continues with sample preparation with broader focus on milling. The following experimental part examines basic traits of four materials before and after milling on high-speed rotor mill using multiple sieves of varying fineness. The traits were determined using normalised methods. For determination of moisture had been selected gravimetric method. In this thesis, there is described every procedure and following calculations. The results are stated in tables and processed in graphs.
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Determining the possibilities of increasing binding potencial of fly ash for the usage in cement composites
Jančaříková, Denisa ; Ďurica,, Tibor (referee) ; Klečka,, Tomáš (referee) ; Kulísek, Karel (referee) ; Hela, Rudolf (advisor)
The deliberate use of fly ash in the production of concrete has been used for decades, but recent trends tend to maximise its utility properties. These are different types of activations from chemical through thermal to mechanical. An alkaline agent is added to chemical activation which, by etching the glass structure of the ash grain, promotes its reactivity. Mechanical activation is mainly focused on granulometry and particle size distribution curve. In this thesis three mechanical activation methods are compared: separation the ash into fractions by grain size, mixing these fractions to achieve the ideal particle size distribution curve and grinding. Four types of ash were collected from the Tušimice power plant – ash from individual electrostatic separators (I, II and III) and SESYP ash which represents the total volume of production. Ash from individual separators differ not only in the particle size but also in the chemical composition and reactivity. Better properties generally have smaller ash particles. This is used by mechanical activation by sorting. When mixing the individual ash fractions, the aim is to achieve an optimal grading curve of either the ash itself or the fine particle set in the concrete. In this work, ash is only used to calculate the mixing ratio and the grading curve according to Funk was selected as optimal. The last compared option of activation was grinding ash. Grinding was carried out in an industrial mill for 15, 30, 45, 60 and 75 minutes. The efficiency of the modified ash was monitored for cement paste in terms of rheology and for concrete in terms of consistency, strength and durability. Based on the results we can say that mechanical activation by sorting is suitable for special purposes, but it’s necessary to realise that coarser ash fractions remain unused. When mixing the fractions to ensure matrix density, the efficiency was shown mainly on the durability characteristics. Grinding cause positive effect.
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Kaoline whitness improvement by mechano-chemical treatment
Uher, Samuel ; Bartoníčková, Eva (referee) ; Šoukal, František (advisor)
The thesis deals with the issue of increasing the whiteness of kaolin by acid leaching simultaneously with milling. Kaolin was prepared from kaolin raw material from the Otovice quarry (Sedlecký kaolin a.s.), which was subsequently grined in suspension with oxalic acid, tartaric acid or citric acid in a ball planetary mill. We had been observing the influence of the type and concentration of acid and grinding time on many aspects, such as: the whiteness index, the amount of leached Fe and Ti, the distribution of Fe and Ti in kaolin, and the kaolin structure order.
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