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Wyszukujesz frazę "size distribution" wg kryterium: Temat


Tytuł:
Effects of operating pressure and stand-off distance on coal comminution by waterjet
Autorzy:
Li, Y.
Galecki, G.
Şen, G. A.
Şen, S.
Powiązania:
https://bibliotekanauki.pl/articles/110840.pdf
Data publikacji:
2017
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
coal
waterjet
comminution
particle size distribution
Opis:
Comminution of coal to ultrafine sizes by high-pressure waterjet coupled with cavitation cell provides a novel method for preparation of coal-water fuels for next generation, near-zero emission electric power generation. To establish the fundamental performance of the waterjet mill, the effects of the operating pressure and stand-off distance were comprehensively investigated using a high ash bituminous coal. The comminution products were evaluated in terms of the particle size, particle size distribution, and surface area change. The experimental results indicated that the waterjet-mediated comminution of coal was strongly affected by all these operating parameters. Higher operating pressure led to finer products, while the efficiency of the waterjet mill in terms of particle size strongly depended on the stand-off distance. This research provides a deeper insight into the high-pressure waterjet for coal comminution and a basis for process parameter optimization.
Źródło:
Physicochemical Problems of Mineral Processing; 2017, 53, 1; 394-401
1643-1049
2084-4735
Pojawia się w:
Physicochemical Problems of Mineral Processing
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Mathematical models of particle size distribution in simulation analysis of high-pressure grinding roll operations
Autorzy:
Saramak, D.
Powiązania:
https://bibliotekanauki.pl/articles/110253.pdf
Data publikacji:
2013
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
HPGR
comminution
particle size distribution
ore processing
Opis:
The high-pressure grinding roll (HPGR) technology is currently one of the most efficient methods of hard ore comminution from the scope of the energy consumption. Throughput and energetic models of performance are quite well developed, but technological models predicting the comminution effects still needs an in-depth research. In the paper author presents the method of modeling of HPGR products’ particle size distribution by using suitable mathematical models. A basis of the HPGR perfor-mance assessment and HPGR-based crushing circuits design is a product’s particle size distribution. In order to precisely determine the particle size distribution of a HPGR product, parameters of product’s particle size distributions should be conditional on the main technical parameters of the roller press like operating pressure and the speed of rolls. The most accurate approximation of a distribution of size parti-cle appears to be Weibull’s truncated distribution and it is possible to obtain significant relationships between the approximation formula and the value of operating pressure, or feed characteristics. It makes possible a determination of mass recoveries of the product’s respective size fractions and the productivity planning. Instead of pressure, the other HPGR operating parameters can be applied, but the pressure value appears to produce the most relevant relationship. A determination of HPGR product’s particle size dis-tribution is a basis of the press operation simulation analysis.
Źródło:
Physicochemical Problems of Mineral Processing; 2013, 49, 1; 121-131
1643-1049
2084-4735
Pojawia się w:
Physicochemical Problems of Mineral Processing
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
A study of selected properties of rhenium sulphide dispersion
Autorzy:
Pawlak, D. W.
Parus, J. L.
Skwarek, E.
Janusz, W.
Powiązania:
https://bibliotekanauki.pl/articles/951830.pdf
Data publikacji:
2014
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
rhenium sulphide
particle size distribution
zeta potential
Opis:
Due to potential application of rhenium sulphide in medicine and industry, this study is focused on the properties of synthetic and commercial rhenium sulphide. The main reaction of rhenium sulphide preparation involves potassium perrhenate and sodium thiosulphate in the acidic environment giving a mixture of rhenium sulphide and sulphur. The next step is removing sulphur by its dissolution in ether. Stabilization by Povidone K-25 is needed to obtain rhenium sulphide dispersed with the grain size of 0.5–4 m. The extrapolated value of pHiep for synthesised rhenium sulphide is 2.3 whereas for commercial samples this value is lower than 2. For synthetic sample a dependence of zeta potential on the carrier electrolyte concentration is found. It is larger than that for the commercial sample, probably due to surface oxidation during synthesis or purification.
Źródło:
Physicochemical Problems of Mineral Processing; 2014, 50, 1; 387-397
1643-1049
2084-4735
Pojawia się w:
Physicochemical Problems of Mineral Processing
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Surface probability model for estimation of size distribution on a conveyor belt
Autorzy:
Zhang, Z
Yang, J.
Dou, D.
Powiązania:
https://bibliotekanauki.pl/articles/109982.pdf
Data publikacji:
2014
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
size distribution
surface probability model
conveyor belt
particles
Opis:
Estimation of size distribution by image analysis is a key issue in mineral engineering. However, only the surface information of ore piles can be captured, which is a headache problem in this field while only a few researchers pay attention to this problem. A new surface probability model was proposed for estimation of size distribution on a conveyor belt based on the Chavez Model in this investigation. This model was tested and verified to have smaller errors in single size fraction but have bigger errors in multiple size fractions. Several error trends were found and a correction factor was introduced to correct the higher errors. A series of linear equations were developed to calculate this specific correction factor according to Dm (average particle size) and the height of pile. Therefore, empirical probability can be estimated by the specific correction factor and calculated probability, and the surface information of ore piles can be converted into the global information of piles.
Źródło:
Physicochemical Problems of Mineral Processing; 2014, 50, 2; 591-606
1643-1049
2084-4735
Pojawia się w:
Physicochemical Problems of Mineral Processing
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Optical sizing of cement particles
Autorzy:
Gorsky, M. P.
Maksimyak, P. P.
Powiązania:
https://bibliotekanauki.pl/articles/174679.pdf
Data publikacji:
2017
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
transverse coherence
polarization interferometer
cement
size distribution function
Opis:
We represent the optical correlation technique of cement particle sizing based on the transverse coherency function measurement using a polarization transverse shearing interferometer. It is shown that a set of particles with random shapes and orientations produces a coherence function, which is the same as a function of the set of spherical particles. The proposed technique of experimental data processing decreases the dependence of the result on interferometer noise, emission source intensity fluctuations and differences in the refraction index of isolated cement particles. The described technique allows fast and high reliable determining of the size distribution function parameters for a set of cement particles.
Źródło:
Optica Applicata; 2017, 47, 4; 511-519
0078-5466
1899-7015
Pojawia się w:
Optica Applicata
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Evolution of droplet size distribution in selected nebulizers
Autorzy:
Dobrowolska, Katarzyna
Sosnowski, Tomasz R.
Powiązania:
https://bibliotekanauki.pl/articles/1450682.pdf
Data publikacji:
2020
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
spraying
liquid atomization
aerosol dynamics
particle size distribution
Opis:
Nebulizers are the class of atomizing devices used to disperse liquids to fine droplets. They found their application in selected technological (typically: small-scale) processes, but their most common use is related to the generation of medicinal aerosols for inhalation. In this work we present the experimental data on the evolution of the size distributions of water droplets generated by two nebulizers (pneumatic and vibrating-mesh) as a result of aerosol mixing with the ambient air. Such a process reflects the real situation, where aerosol emitted from a nebulizer is diluted by additional air sucked by a patient during inhalation. Droplet size distribution was determined by laser diffraction, and these results were further discussed including the data of the aerosol velocity measured by the Laser Doppler Anemometry (LDA). It was demonstrated – as expected - that dilution with the ambient air with moderate humidity results in the intense evaporation of the smallest droplets. However, larger droplet may be saved to a different degree depending on the velocity and geometry of the aerosol cloud emitted from the nebulizer, and on the volume of the diluting air. These parameters have an influence on the droplet coalescence which is another process shaping the droplet size distribution in the studied conditions. The results can deepen the understanding of the mist dynamics which can be applied in various fields of colloidal science and technology.
Źródło:
Physicochemical Problems of Mineral Processing; 2020, 56, 6; 32-40
1643-1049
2084-4735
Pojawia się w:
Physicochemical Problems of Mineral Processing
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
An evaluation of a modified product size distribution model based on t-family curves for three different crushers
Autorzy:
Umucu, Y.
Deniz, V.
Unal, N.
Powiązania:
https://bibliotekanauki.pl/articles/110242.pdf
Data publikacji:
2013
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
crusher
drop weight tests
t-family
size distribution
Opis:
Crushing is a process which is widely used in mineral processing plants, cement factories, aggregates plants and some other industrial plants. Specific fracture energy of the particles is not the only fundamental property that is important: the particle strength also plays a significant role in determining the overall comminution properties of the material. In the drop weight test, a known mass falls through a given height onto a single particle providing an event that allows characterization of the ore under impact breakage. It is known that there are many difficulties and problems in the drop weight and twin pendulum test methods such as being laborious, requiring long test time and requiring a special apparatus. In this study, breakage behavior of slag in different laboratory crushers was investigated. A new size distribution model equation was developed by a t-family value evaluation approach, and the validity of equation was tested.
Źródło:
Physicochemical Problems of Mineral Processing; 2013, 49, 2; 473-480
1643-1049
2084-4735
Pojawia się w:
Physicochemical Problems of Mineral Processing
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Mineral matter in municipal solid waste
Autorzy:
Sniadecka, N.
Tonderski, A.
Hanel, A.
Wojda-Gburek, J.
Hupka, J.
Powiązania:
https://bibliotekanauki.pl/articles/110706.pdf
Data publikacji:
2016
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
mineral matter
municipal waste
separation technologies
size distribution
Opis:
Municipal solid waste (MSW) contains mineral materials which are seldom considered as a potential resource. Currently, the waste management sector pays attention to recyclable parts, biodegradable material, waste-to-energy fraction, and residues after waste reuse and recycle. In contrast, this study focus as on the mineral matter in MSW. The aim was to analyze and discuss the sources of mineral matter in MSW, the impact which the minerals have on waste management technologies, and finally, the possibility to recycle the mineral matter. The contribution of inorganic matter in the MSW stream is significant (about 20 wt.%). In the years 2012–2015, the average content of mineral matter in mixed MSW in Poland ranged from 16 wt.% to 36 wt.%, and the content of organic in MSW ranged from 20 wt.% to 42 wt.%. Minerals in MSW have rather negative impact on waste management technologies and their final products, and can be sorted out from the MSW stream, either in the households or in a central sorting line. However, in central collection and separation systems it is difficult to obtain a mineral matter fraction in subsequent processing steps due to technological limitations (inefficiency of devices), high degree of waste fragmentation and pollution of mineral matter with other waste. This indicates a hampered ability to separate minerals in a form available for reuse, so an effective system should be based on improved segregation at the source.
Źródło:
Physicochemical Problems of Mineral Processing; 2016, 52, 2; 973-990
1643-1049
2084-4735
Pojawia się w:
Physicochemical Problems of Mineral Processing
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Selected mineral materials grinding rate and its effect on product granulometric composition
Autorzy:
Olejnik, T. P.
Powiązania:
https://bibliotekanauki.pl/articles/110220.pdf
Data publikacji:
2013
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
ball mill
specific grinding rate
contact points
size distribution
Opis:
The article presents investigation on the grinding rate constant. A selection function was measured for different raw materials using a ball mill, and effects of the grinding ball diameter and feed particle sizes on the materials grinding rate constant were investigated. The study was conducted for the mill on a semi-technical scale. The process was carried out periodically using several sets of grinding media. Relations for all investigated materials were expressed by the modified Snow equation. Additionally, the descriptions of the grinding rate was examined. The tendency in the variation of the grinding rate constant with the particle size was similar for all materials used, and was independent of the ball diameter. The author used two selection functions derived theoretically by Tanaka.
Źródło:
Physicochemical Problems of Mineral Processing; 2013, 49, 2; 407-418
1643-1049
2084-4735
Pojawia się w:
Physicochemical Problems of Mineral Processing
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Structure of aluminosilicate-supported nickel and iron oxides nanocomposites in gaseous and aqueous media
Autorzy:
Goncharuk, Olena
Dyachenko, Alla
Skwarek, Ewa
Ischenko, Olena
Andriyko, Lyudmila
Borysenko, Mykola
Sulym, Iryna
Sternik, Dariusz
Kowalska, Klaudia
Marynin, Andrii
Powiązania:
https://bibliotekanauki.pl/articles/2146949.pdf
Data publikacji:
2022
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
oxide nanocomposites
NiO/FexOy
textural properties
particle size distribution
Opis:
A series of mixed oxides was synthesized by deposition of a guest phase on a highly dispersed oxide matrix. Fumed nanooxides SiO2, Al2O3, SiO2/Al2O3, and SiO2/Al2O3/TiO2 with the specific surface area of 65-91 m2/g were selected as highly dispersed matrices. NiO/FexOy was deposited as a guest oxide using solvate-stimulated modification of a surface of fumed nanocarriers with nickel nitrate and iron(III) formate and subsequent heat treatment up to 600 °C to form NiO/FexOy. The aim of this work was to study the influence of the composition and structure of fumed oxide matrices and deposited guest phase on the behavior of the composites in gaseous and aqueous media using XRD, nitrogen adsorption and SEM/EDX, and quasi-elastic light scattering (QELS) methods. The lowtemperature nitrogen adsorption isotherms have a sigmoid shape with a narrow hysteresis loop characteristic of mesoporous materials. The specific surface area of composites varies from 65 to 120 m2/g. SEM data show denser aggregate structure of nanocomposites compared to the initial carriers. The primary particle size was in the 30-60 nm range. According to QELS data, there is a tendency to form aggregates of 100 nm - 10 µm in size in the aqueous media. The XRD method shows that the deposited metal oxides are in the form of crystalline phases of NiO with crystallites of 7-23 nm in size, but the iron oxide reflexes were not identified for NiO-containing composites.
Źródło:
Physicochemical Problems of Mineral Processing; 2022, 58, 2; art. no. 144375
1643-1049
2084-4735
Pojawia się w:
Physicochemical Problems of Mineral Processing
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Proposal of concept for structural modelling of hybrid beams
Autorzy:
Kożuch, Maciej
Skrętkowicz, Łukasz
Powiązania:
https://bibliotekanauki.pl/articles/2172884.pdf
Data publikacji:
2022
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
sand
mean grain size
mean pore size model
pore size distribution
water retention curve
Opis:
Investigation on the behaviour of a hybrid beam is presented. Hybrid beam stands for an element with hybrid cross sections. This means sections that consist of steel and concrete parts, connected together with composite dowels, and both are considered for shear flow analysis. In practice, a more general solution may be used for bridges in the form of a beam in which the span sections are hybrid and the support sections are concrete. Recently such a solution has been introduced for bridge engineering in Poland and a new problem with performing a global analysis of hybrid beams was identified. The solution is new itself and requires also a new approach for internal forces determination. Discussion of this problem is made in the paper. Influences of (1) concrete cracking, (2) rheology of concrete and (3) methods of modelling on the redistribution of internal forces are highlighted. On an example of one of the real bridge girder (being currently under design) analysis is made to show how the abovementioned factors are affecting obtained results. Results are analysed and conclusions are presented. As a final step, a new concept of hybrid beam design is proposed. The proposed solution enables a quick and easy engineering approach to perform a static calculation of the considered structure.
Źródło:
Studia Geotechnica et Mechanica; 2022, 44, 4; 317--332
0137-6365
2083-831X
Pojawia się w:
Studia Geotechnica et Mechanica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Investigation of laboratory conditions effect on prediction accuracy of size distribution of industrial ball mill discharge by using a perfect mixing model. A case study: Ozdogu copper-molybdenum plant
Autorzy:
Gharehgheshlagh, H. H.
Ergun, L.
Chehreghani, S.
Powiązania:
https://bibliotekanauki.pl/articles/110599.pdf
Data publikacji:
2017
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
ball mill scale-up
perfect mixing model
particle size distribution
simulation
Opis:
In this study, the perfect mixing model was used to investigate its accuracy level, under different laboratory conditions, in predicting the particle size distribution of industrial ball mills discharges. For this purpose, data sets of two laboratory ball mills with eight different compositions of balls and two industrial mills of a copper processing plant for seven different tonnages, which totally included 56 simulation operations, were used. For simulation, the necessary data were obtained through performing the breakage distribution function and kinetic grinding tests using laboratory mills. The results were used to determine the first order grinding kinetics and normalized breakage rate parameters. For the industrial scale, the simulation process was carried out using data, perfect mixing model equations and JKSimMet software. The results showed that the operating conditions of the laboratory mills were quite affected by the predictive power of the desired model. Comparing the measured and simulated values of P80, it is clear that 2 minutes of first order grinding using the Bond laboratory ball mill with standard operating conditions and single size ball load of 20 mm provided the best prediction with trivial errors, less than 10%, for all seven tonnages of the industrial mills. The results of this study together with more investigations on different plants can be helpful in optimization, simulation and scale-up procedures of ball mills.
Źródło:
Physicochemical Problems of Mineral Processing; 2017, 53, 2; 1175-1187
1643-1049
2084-4735
Pojawia się w:
Physicochemical Problems of Mineral Processing
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
An analytical model to predict water retention curves for granular materials using the grain-size distribution curve
Autorzy:
Bouacida, Linda
Feia, Sadok
Denine, Sid Ali
Della, Noureddine
Powiązania:
https://bibliotekanauki.pl/articles/2172891.pdf
Data publikacji:
2022
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
sand
mean grain size
mean pore size
density index
model
pore size distribution
water retention curve
Opis:
The present work aims to propose a new analytical model intended to predict the water retention curves for granular materials based on data from tensiometric tests. Different analytical models have been used for the evaluation of soil water retention curves so far. It should be noted that the proposed model considers only one criterion in the selection of soils. This criterion is the physical property of particle distribution curve that can be used to determine the values of D50 and CU. In this study, the pore-access size distribution is investigated considering the effect of the coefficient of uniformity of sandy soils that were prepared with different density indexes (0.5, 0.7, and 0.9). Moreover, the proposed model equation is based on the physical properties of soil. This equation made it possible to describe the water retention curve and to estimate the pore-access size distribution without performing any experimental tests. The findings allowed asserting that the uniformity of the particle size curves corresponds to a good uniformity of the pore-access size distribution. In addition, it was revealed that the suction increased as the density index went up, which matches well with the experimental data. Moreover, it may clearly be noted that the distinctive retention properties of unsaturated soils can be observed on the above-mentioned curves. Further, it was found that the ratio of the grain size over the pore-access size increased as the uniformity coefficient augmented.
Źródło:
Studia Geotechnica et Mechanica; 2022, 44, 4; 354--369
0137-6365
2083-831X
Pojawia się w:
Studia Geotechnica et Mechanica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Analysis of large particle sizes using a machine vision system
Autorzy:
Zhang, Z.
Yang, J.
Su, X.
Ding, L.
Powiązania:
https://bibliotekanauki.pl/articles/109404.pdf
Data publikacji:
2013
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
machine vision
particle size distribution
equivalent ellipse
best-fit rectangle
representing analysis
Opis:
Many methods based on machine vision were used to estimate coarse particles size distribution in recent years, but comparison of accuracy parameters representing particle size has not been carried out and a related representing analysis has not been yet proposed. Nine parameters were investigated. The results indicated the minor axis of equivalent ellipse and breadth of the best-fit rectangle were the most suitable for representing particle size. The former accuracy ratio was 86.43% and the latter accuracy ratio was 85.39%, while the accuracy of other parameters was less than 70%. A related representing analysis was proposed to explain this phenomenon. This research is instructive and meaningful for the size distribution estimation by machine vision.
Źródło:
Physicochemical Problems of Mineral Processing; 2013, 49, 2; 397-405
1643-1049
2084-4735
Pojawia się w:
Physicochemical Problems of Mineral Processing
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
The effect of ball size distribution on power draw, charge motion and breakage mechanism of tumbling ball mill by discrete element method (DEM) simulation
Autorzy:
Panjipour, R.
Barani, K.
Powiązania:
https://bibliotekanauki.pl/articles/110020.pdf
Data publikacji:
2018
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
discrete element method
ball mill
ball size distribution
mill power
breakage mechanism
Opis:
In this research, the effect of ball size distribution on the mill power draw, charge motion regime and breakage mechanism in a laboratory ball mill was studied using the discrete element method (DEM) simulation. The mill shell and crushing balls were made of Plexiglas® and compressed glass, respectively. Modeling was performed using Particle Flow Code 3D (PFC3D). Model parameters were back-calculated by comparing the power draws and images obtained from simulation and laboratory test works. After determining the model parameters, the mill was simulated in mill fillings of 15, 20, 25, 30, 35 and 40% with ball media of 2 and 2.5 cm in diameter. For every mill filling, the numbers of big and small balls were changed and 11 scenarios were chosen. The results showed that at a constant mill filling, the power draw was changed with changing the ball size distribution and for all mill fillings the maximum power draw occurred when the fraction of small balls was between 30-40%. The effect of ball size distribution increased with increasing mill filling and for the mill filling of 35%, the ball size distribution had the maximum effect on the power draw. When the mill charge contained mono-sized balls, the ball flow regime inside the mill transited to the cataracting and impact breakage was the main breakage mechanism. Increasing the fraction of big balls from 0 to 70% led the flow of balls into the cascading regime and breakage mechanism to attrition.
Źródło:
Physicochemical Problems of Mineral Processing; 2018, 54, 2; 258-269
1643-1049
2084-4735
Pojawia się w:
Physicochemical Problems of Mineral Processing
Dostawca treści:
Biblioteka Nauki
Artykuł

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