Study on coal microstructure for porosity levels assessment

Miedzińska, Danuta; Niezgoda, T.; Małek, E.; Zasada, D.

doi:10.2478/bpasts-2013-0049

Cited by 3 publications

(3 citation statements)

References 20 publications

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“…The model described above assumes that the particles flocculate during their sedimentation, which accelerates the process. The models available in literature often do not take particle shape into account, while some models assume variable densities [53][54][55]. In this model, the density of particles is constant, which is irrelevant in this case, and the model developed fits all flocculation processes as it takes into consideration intermolecular interactions.…”

Section: Discussionmentioning

confidence: 99%

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Bulletin of the Polish Academy of Sciences: Technical Sciences

Rząsa,

Łukasiewicz

2021

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Coagulation is a process during which a flocculent suspension may sediment. It is characterized by its polydisperse structure. There are three main fractions of sedimentation particles after coagulation: spherical, non-spherical and porous agglomerates. Each of the fractions sediments in a different manner, for different forces act on them, due to interactions between the particles, inhibition or entrainment of neighboring particles. The existing sedimentation models of polydisperse suspension do not consider the flocculation process, i.e. the change of one particle into another during sedimentation, resulting from their agglomeration. The presented model considers the shape of particles and flocculation, which is a new approach to the description of the mathematical process of sedimentation. The velocity of sedimentation depends on the concentration of particles of a given fraction in a specific time step. Following the time step, the heights of individual fractions are calculated. Subsequently, new concentration values of individual fractions are determined for the correspondingly reduced volume of occurrence of a given fraction in the volume analyzed, taking particle flocculation into consideration. The new concentration values obtained in this way allow to recalculate the total sedimentation rates for the next time step. Subsequent iterations allow for numerical simulation of the sedimentation process.

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Section: Discussionmentioning

confidence: 99%

“…On this basis, the concentration of fractions I, II and III are calculated from formulas (47), (48) and (49). The particle numbers of fraction II are then calculated by formula (55), and for fraction III by the formula below:…”

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confidence: 99%

Bulletin of the Polish Academy of Sciences: Technical Sciences

Rząsa,

Łukasiewicz

2021

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“…For example, for samples of chalk and ceramics, the emission spectrum of electric fields is in the range of 10 3 ÷10 7 Hz [24]. Microcracks also form in coal in addition to the natural pores in the coal structure [27].…”

Section: Micro-cracks In the Rock Structurementioning

confidence: 99%

Bulletin of the Polish Academy of Sciences: Technical Sciences

Mydlikowski

Maniak

2021

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The paper analyzes the operation of innovative composite measurement instrumentation for spontaneous electromagnetic emission. The designed receiver measures and records both components of the EM field emitted by rocks subjected to increased mechanical stress. The range of signals transmitted by the receiver system and its dynamics were determined. A receiver was used to observe electromagnetic signals generated during a hard coal sample crushing in laboratory conditions. Test results confirmed the high dynamic range of the system at 98 dB and the ability to observe signals over a range of frequencies up to 50 kHz. The experimental results confirm the signal bandwidth characteristic of coal mine EM field emission obtained in earlier studies. The constructed autonomous receiver can be used in mine workings as a complementary warning system for emerging mine hazards.

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Experimental study on influence of carbon dioxide on porous structure and mechanical properties of shale rock

Miedzińska

2017

Biuletyn WAT

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Shale rocks are geological formations which can be unconventional gas reservoirs. During their interaction with carbon dioxide, which can be used as a fracturing fluid in shale gas recovery process, many phenomena take place that can influence rock structure and mechanical properties. The research on changes in rock structure under super critical carbon dioxide interaction and their influence of shale properties were presented in the paper. The structural tests were carried out with the use of microscopic techniques with different resolutions of visualization. The uniaxial compression test was applied as a mechanical properties assessment experiment. As a research results some dependence was observed. The bigger decrease in porosity after infiltration in lower zooms was, the bigger increase in porosity in high zooms and mechanical properties was noticed. Keywords: geomechnics, shale rock, carbon dioxide.

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Study on coal microstructure for porosity levels assessment

Cited by 3 publications

References 20 publications

Bulletin of the Polish Academy of Sciences: Technical Sciences

Bulletin of the Polish Academy of Sciences: Technical Sciences

Bulletin of the Polish Academy of Sciences: Technical Sciences

Experimental study on influence of carbon dioxide on porous structure and mechanical properties of shale rock

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