Górnictwo i Geoinżynieria
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ISSN 1732-6702
Issue Date
2007
Volume
R. 31
Number
Nr 4
Description
Journal Volume
Górnictwo i Geoinżynieria
R. 31 (2007)
Projects
Pages
Articles
Jak termodynamika i mechanika opisują makroskopową oraz molekularną istotę zwilżalności
(2007) Grodzka, Janina; Pomianowski, Andrzej Aleksander
Recent studies on wetting lead to the two most important conclusions: description (estimation) of wettability needs the knowledge of not only the macroscopic wetting angle but also of the nature of molecular aqueous films that occupy surfaces of all solids; mechanical equilibrium of the wetting process is generally much more rapidly established than the thermodynamic equilibrium of the whole system. In consequence, the macroscopically measured wetting angle is different from the equilibrium angle, when the thermodynamic equilibrium and the formation of the molecular water film on the solid are not attained. Rapidly proceeding investigations of molecular wettability, carried out with the use of AFM (atomic force microscopy), will lead in the near future to unification of the theory and practice of wetting, and in particular will solve the question of the hysteresis of wetting, resulting from changes in the structure of water, directly adjacent to the surfaces of solids.
Zależność napięcia powierzchniowego zwilżania od zawartości popiołu w zbiorze bardzo drobnych ziaren węglowych
(2007) Lenartowicz, Marek
Surface tension of wetting in products obtained from sampling of IZ type flotation machines by film flotation method has been investigated. The obtained results allowed to calculate the equations of regressions which characterize the dependence of surface tension of wetting of particles on the ash content of different rank of coal with the comparatively high correlation coefficient. The equations describing this dependence and research results let us carry out considerations about the relationship between surface properties of particles (surface tension of wetting) and the ash content in the particles. The outcomes of surface tension of wetting calculations of given particles fractions and their ash content showed independently that there exists certain dependency. When the ash content of particles rises, the surface tension of wetting is also higher. This dependence may be used for analysis of work of flotation machines.
Pomiary hałasu na stanowiskach pracy w zakładzie przeróbczym kopalni węgla kamiennego
(2007) Lutyński, Aleksander
In the article measurements of noise level in hard coal processing plants are presented. Apparatus and results of noise measurements at selected thirty six production stands characteristic for coal processing plants are presented. The results of investigation of five employees subjected to noise while moving at the plant are described.
Badania możliwości stosowania we flotacji pakietów wkładów lamelowych
(2007) Marciniak-Kowalska, Jolanta; Wójcik-Osip, Edyta
The paper presents the results of coal suspensions flotation laboratory research in the cell with lamella packets. In the presented investigations, the lamella packets of various working surface and various inclination angles (60 degrees and 90 degrees) were applied. The obtained results of laboratory research show that the effect of, approximately 5 times, increasing of flotation cell surface cause the growth of process efficiency, sustaining the comparable ash contents in flotation concentrates. This may cause the improvement of flotation process economics in future. The applications of packets with inclined to surface by angle 90 degrees influence only on the stabilization of flowing conditions, slightly improving the process efficiency in comparison to the flotation without lamella packets.
Ocena zawartości popiołu w pokładach węgla za pomocą nieparametrycznych metod statystycznych
(2007) Niedoba, Tomasz
The paper presents the distribution of ash contents in coal, treated as the mixture of distributions taken from the individual coal beds. In purpose of their approximation, apart from traditional log-norm distribution function, the non-parametric statistical methods were applied: kernel method and orthogonal Fourier series method. The best results of approximation were then mixed and the risk probability of evaluating the ash contents in the whole deposit was estimated.