scholarly journals Particle size grouping method as a control system of efficiency flotation process on the example of coal

2020 ◽  
pp. 33-33
Author(s):  
Dorota Kalisz ◽  
Kamil Kuglin ◽  
Anna Młynarczykowska
Keyword(s):  
Particle Size ◽  
Fine Particles ◽  
Flotation Kinetics ◽  
Particle Volume ◽  
Initial Size ◽  
Flotation Process ◽  
Carbon Particles ◽  
Coal Particles ◽  
Total Particle ◽  
Size Of Particles

Agglomeration of coal particles during flotation can be analysed with the Particle Size Grouping (PSG) method. Numerous experiments were carried out to theoretically explain the effect of carbon particles agglomeration, but the result still remains incomplete. In this paper the PSG method was used to analyse agglomeration groups of carbon particles of initial size 100-400 ?m, maintaining the total particle volume. The size of particles population with definite radius and density was determined for 1 Mg coal. The influence of density and size of particles with given mixing energies and parameter ? on agglomeration was analysed. It was stated that the size of the particles had an effect on their agglomeration. In the analysed cases the dimensionless parameter of collision turbulence t* needed for particles agglomeration in particular size groups was importantly shorter for particles of initial size 300 and 400 ?m. The change of the mixing energy did not have influence on the agglomeration of coal particles. The theoretical analyses based on computer calculations were supplemented by the analyses of the coal flotation process on an aqueous model. Experiments lied in introducing a foaming agent in the form of aqueous solution of hexanol which, without changing pH of the pulp, lowered surface tension value, and consequently increased the dispersion of air in the suspension. The experimental results were presented in the form of flotation kinetics curves. Fine particles 100-200?m. turned out to be best for flotation, unlike coarse 400-500 ?m.

Effect of Storage in Flour and of Particle Size on the Bioavailability of Elemental Iron Powders for Rats and Humans

1977 ◽  
Vol 60 (4) ◽  
pp. 759-765 ◽  
Author(s):  
Ramesh S Verma ◽  
Ilary Motzok ◽  
Shy-Show Chen ◽  
Jaroslava Rasper ◽  
Henry U Ross
Keyword(s):  
Particle Size ◽  
Carbonyl Iron ◽  
Fine Particles ◽  
Iron Absorption ◽  
Iron Supplement ◽  
Electrolytic Iron ◽  
Biological Value ◽  
Iron Powders ◽  
Elemental Iron ◽  
Size Of Particles

Abstract Elemental iron powders produced by different processes were separated by nitrogen elutriation into fractions based on particle size. The fractions containing fine particles (7–10 μm) of electrolytic iron, hydrogen (H2)- and carbon monoxide (CO)-reduced iron, and the whole sample of carbonyl iron (92% <11 μm) were blended into freshly milled wheat flour and stored at about 21°C. Storing the enriched flour up to 9 months had no effect on the relative biological value (RBV) of iron for rats from each type of iron supplement. Baking bread with flour containing electrolytic, H2-reduced, and carbonyl iron after storage for 10 months also had no effect on the RBV of the iron powders. There was no change in the RBV of iron for rats from flour enriched with electrolytic iron (200 mg/kg) and ascorbic acid (200 and 1665 mg/kg flour) after storage for 1 week and 3 months. The decreases in RBV due to increase in size of particles (7–10 vs. 20–26 μm) were significant for H2-reduced iron and CO-reduced iron but not for electrolytic iron and carbonyl iron. The RBVs of elemental iron powders for rats were similar to the values obtained with humans, based on iron absorption after an overnight fast.

scholarly journals A comparison of light backscattering and particle size distribution measurements in tropical cirrus clouds

2011 ◽  
Vol 4 (3) ◽  
pp. 557-570 ◽  
Author(s):  
F. Cairo ◽  
G. Di Donfrancesco ◽  
M. Snels ◽  
F. Fierli ◽  
M. Viterbini ◽  
...  
Keyword(s):  
Particle Size ◽  
Optical Properties ◽  
Volume Density ◽  
Size Distributions ◽  
Backscatter Coefficient ◽  
Particle Size Distributions ◽  
Particle Volume ◽  
Total Particle ◽  
Research Aircraft

Abstract. An FSSP-100 Optical Particle Counter designed to count and size particles in the micron range and a backscattersonde that measures in-situ particle optical properties such as backscatter and depolarization ratio, are part of the payload of the high altitude research aircraft M55 Geophysica. This aircraft was deployed in tropical field campaigns in Bauru, Brasil (TROCCINOX, 2004) Darwin, Australia (SCOUT-Darwin, 2005) and Ouagadougou, Burkina Faso (SCOUT-AMMA, 2006). In those occasions, measurements of particle size distributions and optical properties within cirrus cloud were performed. Scope of the present work is to assess and discuss the consistency between the particle volume backscatter coefficient observed by the backscattersonde and the same parameter retrieved by optical scattering theory applied to particle size distributions as measured by the FSSP-100. In addition, empirical relationships linking the optical properties measured in-situ by the backscattersonde, which generally can be obtained by remote sensing techniques (LIDAR), and microphysical bulk properties like total particle number, surface and volume density will be presented and discussed.

scholarly journals A comparison of light backscattering and particle size distribution measurements in tropical cirrus clouds

2010 ◽  
Vol 3 (5) ◽  
pp. 4059-4089 ◽  
Author(s):  
F. Cairo ◽  
G. Di Donfrancesco ◽  
M. Snels ◽  
F. Fierli ◽  
M. Viterbini ◽  
...  
Keyword(s):  
Particle Size ◽  
Optical Properties ◽  
Volume Density ◽  
Size Distributions ◽  
Backscatter Coefficient ◽  
Particle Size Distributions ◽  
Particle Volume ◽  
Total Particle ◽  
Research Aircraft

Abstract. An FSSP-100 Optical Particle Counter designed to count and size particles in the micron range and a backscattersonde that measures in-situ particle optical properties such as backscatter and depolarization ratio, are part of the payload of the high altitude research aircraft M55 Geophysica. This aircraft was deployed in tropical field campaigns in Bauru, Brasil (TROCCINOX, 2004) Darwin, Australia (SCOUT-Darwin, 2005) and Ouagadougou, Burkina Faso (SCOUT-AMMA, 2006). In those occasions, measurements of particle size distributions and optical properties within cirrus cloud were performed. Scope of the present work is to assess and discuss the consistency between the particle volume backscatter coefficient observed by the backscattersonde and the same parameter retrieved by optical scattering theory applied to particle size distributions as measured by the FSSP-100. In addition, empirical relationships linking the optical properties measured in-situ by the backscattersonde, which generally can be obtained by remote sensing techniques (LIDAR), and microphysical bulk properties like total particle number, surface and volume density will be presented and discussed.

scholarly journals Rapid formation of large aggregates during the spring bloom of Kerguelen Island: observations and model comparisons

2014 ◽  
Vol 11 (3) ◽  
pp. 4949-4993 ◽  
Author(s):  
M.-P. Jouandet ◽  
G. A. Jackson ◽  
F. Carlotti ◽  
M. Picheral ◽  
L. Stemmann ◽  
...  
Keyword(s):  
Particle Size ◽  
Mixed Layer ◽  
Late Summer ◽  
Surface Mixed Layer ◽  
Particle Volume ◽  
Kerguelen Island ◽  
Underwater Vision ◽  
Rapid Formation ◽  
Total Particle ◽  
Spherical Diameter

Abstract. We recorded vertical profiles of particle size distributions (PSD, sizes ranging from 0.052 to several mm in equivalent spherical diameter) in the natural iron-fertilized bloom southeast of Kerguelen Island (Southern Ocean) from pre-bloom to early bloom stage. PSD were measured by the Underwater Vision Profiler during the Kerguelen Ocean and Plateau Compared Study cruise 2 (KEOPS 2, October–November 2011). The total particle numerical abundance was more than 4 fold higher during the early bloom phase compared to pre-bloom conditions as a result of the 2-weeks bloom development. We witnessed the rapid formation of large particles and their accumulation at the base of the mixed layer within a two days period, as indicated by changes in total particle volume (VT) and particle size distribution. The VT profiles suggest sinking of particles from the mixed layer to 200 m, but little export deeper than 200 m during the observation period. The results of a one dimensional particles dynamic model support coagulation as the mechanism responsible for the rapid aggregate formation and the development of the VT subsurface maxima. Comparison with KEOPS1, which investigated the same area during late summer, and previous iron fertilization experiments highlights physical aggregation as the primary mechanism for large particulate production during the earlier phase of iron fertilized bloom and its export from the surface mixed layer.

scholarly journals On the issue of wood dust deposition in the electrocyclone

2017 ◽  
Author(s):  
В.А. Прусакова ◽  
В.П. Кривоколеско ◽  
В.А. Рогов
Keyword(s):  
Particle Size ◽  
Electrostatic Field ◽  
Fine Particles ◽  
Air Flow ◽  
Wood Dust ◽  
Centrifugal Forces ◽  
Dust Deposition ◽  
Size Of Particles ◽  
Curvilinear Trajectory ◽  
Harmful Effects

Деревообрабатывающая промышленность сегодня развивается быстрыми темпами, оказывая вредное воздействие на состояние окружающей среды и, следовательно, на здоровье населения. Наиболее эффективными пылеулавливающими аппаратами для очистки пылевоздушного потока в деревообрабатывающих цехах являются электроциклоны. В них частицы древесной пыли удаляются под воздействием центробежных и электрических сил. Для увеличения эффективности очистки пылевоздушного потока необходимо увеличение размера частиц. Силы электрической природы эффективно влияют на взаимодействие дисперсных частиц в системе и приводят к существенным изменениям в дисперсном составе. При воздействии электростатического поля на тонкодисперсные частицы древесной пыли происходит их коагуляция. Приведены теоретические исследования движения пылевоздушного потока в электростатическом поле, проведены математические расчеты. Выявлены силы, действующие на частицу пыли в электростатическом поле. Получено уравнение траектории движения частиц под действием электростатического поля. В результате частица движется по криволинейной траектории, при этом чем больше размер частицы, тем быстрее происходит процесс осаждения. Чем меньше размер частицы, тем ближе ее траектория к окружности и тем медленнее она осаждается. Эффективность очистки увеличивается с увеличением размера частиц. При влиянии электростатического поля в циклоне на частицу действует электрическая сила, которая не дает выброса частиц менее 10 мкм. Частицы разных размеров при воздействии электростатической и центробежной сил осаждаются с высокой эффективностью. Таким образом, расчетным путем установлена высокая степени очистки воздуха от тонкодисперсных частиц древесной пыли в электроциклоне. Достигается высокая суммарная степень очистки, тем самым коэффициент степени очистки в электроциклоне достигает 99,9%. The woodworking industry develops in high gear today, making harmful effects on state of environment, and, therefore, on health of the population. The most effective dust removal devices for cleaning dust-air flow in woodworking shops are electrocyclones. In them particles of wood dust are removed under the influence of centrifugal and electric forces. For increase in efficiency of cleaning dust-air flow there is a need of increase in the size of particles. Forces of the electric nature effectively influence interaction of disperse particles in system and lead to essential changes in disperse structure. In case of impact of electrostatic field on fine particles of wood dust there is their coagulation. Theoretical researches of movement dust-air flow are given in electrostatic field, mathematical calculations are carried out. Forces operating on a dust particle in electrostatic field are revealed. The equation of a trajectory of motion of particles under the influence of electrostatic field is received. As a result the particle moves on a curvilinear trajectory, at the same time, the more the particle size, the quicker there is a sedimentation process. The particle size is less, the closer it a trajectory to a circle and the more slowly it is besieged. Efficiency of cleaning increases with increase in the size of particles. In case of influence of electrostatic field in a cyclone the particle is affected by the electric force which doesn't give emission of particles less than 10 microns. Particles of the different sizes in case of impact of electrostatic and centrifugal forces are besieged with outstanding performance. Thus, by a settlement way it is established high extents of purification of air of fine particles of wood dust in an electrocyclone. High total extent of cleaning is reached, thereby, the coefficient of extent of cleaning in an electrocyclone reaches 99,9%.

scholarly journals Understanding the Optical Properties of Ambient Sub- and Supermicron Particulate Matter: Results from the CARES 2010 Field Study in Northern California

2016 ◽  
Author(s):  
Christopher D. Cappa ◽  
Katheryn R. Kolesar ◽  
Xiaolu Zhang ◽  
Dean B. Atkinson ◽  
Mikhail S. Pekour ◽  
...  
Keyword(s):  
Particle Size ◽  
Optical Properties ◽  
Average Particle Size ◽  
Submicron Particles ◽  
Average Particle ◽  
Carbonaceous Aerosols ◽  
Total Particle ◽  
Size Of Particles ◽  
Pm2.5 And Pm10 ◽  
Photochemical Age

Abstract. Measurements of the optical properties (absorption, scattering and extinction) of PM1, PM2.5 and PM10 made at two sites around Sacramento, CA during the June 2010 Carbonaceous Aerosols and Radiative Effects Study (CARES) are reported. These observations are used to establish relationships between various intensive optical properties and to derive information about the dependence of the optical properties on photochemical ageing and sources. Supermicron particles contributed substantially to the total light scattering at both sites, about 50 % on average. A strong, linear relationship is observed between the scattering Ångstrom exponent for PM10 and the fraction of the scattering that is contributed by submicron particles (fsca,PM1) at both sites and with similar slopes and intercepts (for a given pair of wavelengths), suggesting that the derived relationship may be generally applicable for under standing variations in particle size distributions from remote sensing measurements. At the more urban T0 site, the fsca,PM1 increased with photochemical age whereas at the downwind, more rural T1 site the fsca,PM1 decreased slightly with photochemical age. This difference in behavior reflects differences in transport, local production and local emission of supermicron particles between the sites. Light absorption is dominated by submicron particles, but the there is some absorption by supermicron particles (~15 % of the total). The supermicron absorption derives from a combination of black carbon that has penetrated into the supermicron mode and from dust, and there is a clear increase in the mass absorption coefficient of just the supermicron particles with increasing average particle size. The mass scattering coefficient (MSC) for the supermicron particles was directly observed to vary inversely with the average particle size, demonstrating that MSC cannot always be treated as a constant in estimating mass concentrations from scattering measurements, or vice versa. The total particle backscatter fraction exhibited some dependence upon the relative abundance of sub-versus supermicron particles, however this was modulated by variations in the median size of particles within a given size range; variations in the submicron size distribution had a particularly large influence on the observed backscatter efficiency and an approximate method to account for this variability is introduced. The relationship between the absorption and scattering Ångstrom exponents is examined and used to update a previously suggested particle classification scheme. Differences in composition led to differences in the sensitivity of PM2.5 to heating in a thermodenuder to the average particle size, with more extensive evaporation (observed as a larger decrease in the PM2.5 extinction coefficient) corresponding to smaller particles, i.e. submicron particles were generally more susceptible to heating than the supermicron particles. The influence of heating on the particle hygroscopicity varied with the effective particle size, with larger changes observed when the PM2.5 distribution was dominated by smaller particles.

scholarly journals Study on Microstructure Effect of Carbon Black Particles in Filled Rubber Composites

2018 ◽  
Vol 2018 ◽  
pp. 1-11 ◽  
Author(s):  
Li Hong Huang ◽  
Xiaoxiang Yang ◽  
Jianhong Gao
Keyword(s):  
Particle Size ◽  
Carbon Black ◽  
Polymer Nanocomposites ◽  
Volume Fraction ◽  
Particle Volume Fraction ◽  
Uniaxial Tensile ◽  
Particle Volume ◽  
Carbon Particles ◽  
The Difference ◽  
Microstructure Effect

The cross sections of blended natural/styrene-butadiene (NSBR) composites filled with different volume fractions of carbon particles were observed using a Quanta 250 scanning electron microscope. In addition, the sizes and distributions of the carbon particles were analyzed using Nano Measurer. A two-dimensional representative volume element model (RVE) for a rubber composite reinforced with circular carbon particles was established, and the uniaxial tensile behaviors of polymer nanocomposites with different particle size distribution patterns were simulated using the ABAQUS software. The results showed the following. (1) For the random models, if the difference of particle size was larger and particle distance was closer, stress distribution would be denser as well as the stress concentration would become greater. However, if the difference of particle size was small, for the case of same particle volume fraction, the particle size has little influence on the macromechanical properties whether the average size is large or small. (2) The correlation between the volume fraction and distribution of the carbon particles revealed that when the volume fraction of carbon black particles was larger than 12%, clusters between carbon particles in the polymer nanocomposites could not be avoided and the modulus of the composites increased with an increase in the cluster number.

scholarly journals Study of Combustion Characteristics of Carbon Particles Clouds

2015 ◽  
Vol 16 (1) ◽  
pp. 210-216
Author(s):  
S. G. Orlovska
Keyword(s):  
Mass Concentration ◽  
Fine Particles ◽  
Equal Mass ◽  
Coarse Particles ◽  
Burning Time ◽  
Carbon Particles ◽  
Coal Particles ◽  
Surface Burning ◽  
Temperature Heat ◽  
The Mean

High temperature heat and mass transfer and chemical kinetics are modeled in polydisperse cloud of coal particles taking into consideration reactions in pores and Stefan flow at the surface. Burning characteristics are calculated of bimodal aerosol, with the assumption of equal mass concentration of two fractions with two or three-fold difference between the mean particles diameters. It is shown that ignition delay of coarse particles in bimodal aerosol is significantly less than that of equal size particles in monodisperse aerosol. Also a burning time of fine particles is substantially less in bimodal aerosol. It is demonstrated that burning temperature is higher in case of bimodal aerosol in comparison with monodisperse one.

scholarly journals Increasing Spontaneous Combustion Risk While Reducing the Coal Particle Size

2019 ◽  
Vol 105 ◽  
pp. 01029
Author(s):  
Vyacheslav Portola ◽  
Hi Un Lee ◽  
Denis Botvenko ◽  
Vladimir Ludzish ◽  
Arhip Pavlov
Keyword(s):  
Particle Size ◽  
Incubation Period ◽  
Coal Particle ◽  
Spontaneous Combustion ◽  
Coal Dust ◽  
Chemical Activity ◽  
Technological Processes ◽  
Toxic Gases ◽  
Coal Particles ◽  
Size Of Particles

Extraction, storage and transportation of coal are complicated by the danger of spontaneous combustion centers due to toxic gases emission. At various technological processes, the formation of clusters consisting of coal particles of various sizes is possible. In the course of the research, the influence of the size of coal particles on the danger of spontaneous combustion of oxidizing material clusters was estimated. The studies of coal chemical activity have shown that for most seams of Kuzbass mines, the amount of absorbed oxygen increases significantly with decreasing particle size. Coal dust can be more active than coal in 3-8 times. For some seams, the coal breakage has almost no effect on its chemical activity in relation to oxygen. It is determined that the duration of incubation period of spontaneous combustion also varies depending on the size of particles forming the coal cluster. For the appearance of spontaneous combustion centers, the size of coal dust clusters may be in 2– 4 times smaller than for coal. In order to increase the safety of work for all the seams it is necessary to study the chemical activity in relation to oxygen, the tendency to spontaneous combustion, and the duration of the incubation period not only for coal samples, but also for coal dust.

Contribution of Calcite to the Particle-Size Spectrum of Lake Michigan Seston and Its Interactions with the Plankton

1987 ◽  
Vol 44 (11) ◽  
pp. 1898-1914 ◽  
Author(s):  
Henry A. Vanderploeg ◽  
Brian J. Eadie ◽  
James R. Liebig ◽  
Stephen J. Tarapchak ◽  
Rebecca M. Glover
Keyword(s):  
Particle Size ◽  
Feeding Rate ◽  
Lake Michigan ◽  
Light Extinction ◽  
Size Spectrum ◽  
Calcite Precipitation ◽  
Particle Volume ◽  
Total Particle ◽  
Different Seasons ◽  
A Minor

We determined the contribution of calcite to the total particle-size spectrum of Lake Michigan seston during different seasons in 1978–83 and 1985, employing a novel Coulter counter method, to examine the intensity and ecological effects of calcite whitings that result from autogenic precipitation of calcite. The whitings were most intense during September, when 12–56% of the total particle volume was calcite. Overall, food web dynamics were more controlling of than controlled by whitings. Year-to-year variation in calcite concentration was probably caused by predation-controlled variation in primary production, which drives calcite precipitation through CO2 uptake. Feeding rate of cladocerans in Lake Michigan is slightly reduced (16%) by calcite, but that of copepods is not. Light extinction is only slightly increased. Coprecipitation and sinking of P with calcite is probably a minor factor in regulating P concentration in the epilimnion of Lake Michigan. Removal of nutrients is enhanced by increased sinking rates caused by inclusion of calcite in fecal pellets and matter. Although all of the effects of calcite on plankton dynamics appear to be subtle in Lake Michigan, large effects can be expected for lakes of greater calcium hardness and eutrophy.

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