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1
Content available The accurate algorithm of new surface area of single particle comminution, incorporating particle shape and roughness
Guo Qing, Zhou Qiang, Pan Yongtai, Zhu Changyong, Wei Yinghua
Physicochemical Problems of Mineral Processing
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2021
|
Vol. 57, iss. 1
259--272
EN
Energy efficiency can be obtained by measuring accurate new surface energy in the crushing process. For the calculation of new surface energy, most researchers only pay attention to particle size distribution and ignore the influence of particle shape and roughness on the surface area. In this paper, the image processing technology was used to calculate the shape parameters and surface fractal dimension of the crushed granite sample. According to the different combinations of particle shape and roughness, the new surface area corresponding to the four basic models was calculated. For the surface area of a single particle, the calculation result of the rough model considering the surface fractal dimension is higher than that of the smooth model. Moreover, the ratio of the calculation results of the rough model and the smooth model increases significantly as the particle size increases. For 0.1 mm particles, the area ratio of the two models is 8, but for 25 mm particles, the area ratio reaches 130. In contrast, the particle shape is a secondary factor that affects the surface area calculation. The ellipsoidal model considering the particle shape has a surface area 30% larger than the spherical model. If the roughness and particle shape are considered when calculating the surface area, the energy efficiency of crushing is higher.
2
Wpływ właściwości kruszyw na procesy ich klasyfikacji
Ławińska Katarzyna, Modrzewski Remigiusz
Kruszywa : produkcja - transport - zastosowanie
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2020
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Nr 2
38--47
PL
Niniejsza praca analizuje wpływ właściwości materiałów sypkich i kruszyw mineralnych na proces przesiewania tych mediów ziarnistych. Właściwości te to przede wszystkim wilgotność materiału i związany z nią współczynnik tarcia wewnętrznego, jak również kształt i rozmiary ziaren. Ponadto wprowadzono pojęcie tzw. funkcji wypływu, która również może być ważnym narzędziem opisującym właściwości materiałów w ich procesach przeróbczych.
EN
This paper analyses the influence of the properties of bulk materials and mineral aggregates on the sieving process of these granular materials. These properties include first of all: the water content of a material and the relevant coefficient of internal friction as well as particle shape and size. Moreover, the notion of the so called outflow function is introduced, which can be an important tool describing the properties of materials during their processing.
3
Content available Effects of ultrasonic treatment on the particle size, shape and ash content of fine coal
Mao Yuqiang, Xie Guangyuan, Liang Long, Xia Wencheng, Peng Yaoli
Physicochemical Problems of Mineral Processing
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2019
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Vol. 55, iss. 3
679--688
EN
The effects of ultrasonic treatment of different time on the particle size, morphology, ash content, and elementary composition of fine coal particles (74-45 μm) were investigated in this paper. The size reduction of coal particles induced by ultrasonic treatment was analyzed through the Focused Beam Reflectance Measurement (FBRM) and the variation of mechanical pulverization mechanism was discussed. The Scanning Electron Microscope (SEM) measurements showed that the sharp corners on coal particles was ground to round ones after ultrasonic treatment. This may be not conducive to coal flotation. It was also found that the ash content of 74-45 μm coal particles was increased gradually with the increase of ultrasonic time, while the ash content of -45 μm fraction was decreased. This was supported by the EDS measurements, indicating that the carbon content on the surfaces of 74-45 μm coal was reduced while the aluminium and silicon contents were increased after ultrasonic treatment.
4
Content available Investigation on the particle size and shape of iron ore pellet feed using ball mill and HPGR grinding methods
Abazarpoor A., Halali M.
Physicochemical Problems of Mineral Processing
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2017
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Vol. 53, iss. 2
908--919
EN
An effect of a grinding method, that is ball mill and high pressure grinding rolls (HPGR), on the particle size, specific surface area and particle shape of an iron ore concentrate was studied. The particle size distribution was meticulously examined by sieve, laser and image analyses. To measure the specific surface area of particles, Brunauer-Emmett-Teller (BET) and Blaine methods were used. It was found that for samples having equal Blaine specific surface areas numbers, the amount of fine particles produced in HPGR was higher than that produced in a ball mill. A higher surface area was observed from HPGR treatment in comparison to ball mill grinding, provided by a higher porosity, cracks, roughness and new surfaces. A shape factor of particles was determined using the circularity, roughness, and aspect ratio. It was also observed that HPGR produced particles that were more elongated, less circular and rougher than those processed by the ball mill.
5
Content available Zastosowanie metody DEM do badania wpływu kształtu ziaren na charakter wysypu materiału rozdrobnionego podczas opróżniania silosu
Chutkowski M., Zapała W.
Inżynieria i Aparatura Chemiczna
|
2015
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Nr 3
71--73
PL
W oparciu o metodę DEM przeprowadzono symulacje komputerowe procesu opróżniania modelowego silosu, które pozwoliły zbadać wpływ kształtu ziaren trzech materiałów roślinnych na profile porowatości lokalnej w charakterystycznych punktach. Uzyskane w wyniku badań zróżnicowane rodzaje wysypu pozwoliły na zaproponowanie bezwymiarowego kryterium pomocnego w ilościowej ocenie charakteru wysypu ziaren, na podstawie przebiegu profili porowatości lokalnych podczas wysypu.
EN
On the basis of DEM method computer simulations of silo discharge process were performed and the effect of particle shape for three plant materials on local porosity profiles in selected characteristic regions of a model silo were investigated. The obtained various types of powder motion allowed the formulation of new dimensionless criterion for a quantitative assessment of powder flow type to be proposed on the basis of local porosity course during the model silo discharge.
6
Content available Particle shape effect on macroscopic behaviour of underground structures: numerical and experimental study
Szarf K., Combe G., Villard P.
Studia Geotechnica et Mechanica
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2014
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Vol. 36, nr 3
67--74
EN
The mechanical performance of underground flexible structures such as buried pipes or culverts made of plastics depend not only on the properties of the structure, but also on the material surrounding it. Flexible drains can deflect by 30% with the joints staying tight, or even invert. Large deformations of the structure are difficult to model in the framework of Finite Element Method, but straightforward in Discrete Element Methods. Moreover, Discrete Element approach is able to provide information about the grain–grain and grain–structure interactions at the microscale. This paper presents numerical and experimental investigations of flexible buried pipe behaviour with focus placed on load transfer above the buried structure. Numerical modeling was able to reproduce the experimental results. Load repartition was observed, being affected by a number of factors such as particle shape, pipe friction and pipe stiffness.
7
Pomiar kształtu i wielkości cząstek : automatyczna analiza obrazu
Arcichowski P.
LAB Laboratoria, Aparatura, Badania
|
2006
|
R. 11, nr 4
12-16
8
Content available remote Percolation threshold model and its application to the electrical conductivity of layered BaTiO3-Ni
Ambrozic M., Dakskobler A., Valant M., Kosmac T.
Materials Science Poland
|
2005
|
Vol. 23, No. 2
535--539
EN
The electrical conductivity percolation threshold of the materials composed of conducting particles embedded in a non-conducting host matrix has been investigated. A statistical, numerical method was used, in which the particles are randomly placed, one by one, into the non-conducting host, and the conducting path is searched. The influence of different particle shapes on the percolation threshold is considered. It has been found that, in addition to the anisotropy in the dimensions of particles, the angular distribution of their long axes plays a dominant role in the calculations of the conductivity percolation threshold. Finally, the non-uniform space distribution of positions of particles is taken into account and the model is used to analyze the percolation threshold of the AC conductivity of layered BaTiO3- Ni composites.
9
Rozbieżności wyników analiz granulometrycznych
Składzień J., Szymków J.
Inżynieria i Aparatura Chemiczna
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2004
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Nr 3s
139-140
EN
In the paper a random vector describing geometrical parameters of particle and an n-dimensional probability density function were considered. Discrepancies of granulometric analyses were discussed and illustrated via experiments.
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