Segregation of Construction Materials in Silos. Part 2: Identification of Relevant Segregation Mechanisms

Engblom, Niklas; Saxén, Henrik; Zevenhoven, Ron; Nylander, H; Enstad, Gisle G.

doi:10.1080/02726351.2011.552097

Cited by 11 publications

(16 citation statements)

References 13 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…However, the magnitude of segregation for these products cannot be clearly differentiated perhaps with the exception of products P1 (at low filling rate) and P2 (at high filling rate) being slightly more prone to segregate compared to the other products. Our previous work 14,15 showed that all products tested for sifting/rolling segregation induce an unconventional segregation pattern at discharge from the surge silo shown in Figure 5. For P2 a surplus of fine particles was observed at the silo walls during filling, and for all products the mass fraction of fines increased at the end of emptying.…”

Section: Preliminary Testsmentioning

confidence: 95%

See 1 more Smart Citation

Analysis of Segregation Data for a Dry Mineral-Based Construction Materials Plant

Engblom

Saxén

Zevenhoven

et al. 2012

Ind. Eng. Chem. Res.

View full text Add to dashboard Cite

In this work, segregation data for seven commercial products at a dry mineral-based construction materials plant have been analyzed. The segregation manifests itself as an increase of the fines content to unacceptable levels at the end of complete emptying from a surge silo situated upstream of packing. Results for preliminary tests for sifting segregation and fluidization show the difficulty in estimating a priori the segregation patterns observed in practice. Knowledge of the segregation mechanisms occurring with similar materials at silo filling and the discharge flow pattern is utilized to explain the segregation at silo emptying: Accumulation of fine particles at the silo walls during filling and discharge in expanded flow cause fines-rich regions from the vicinity of walls in the lower parts of the silo to be withdrawn last. Large variations in the magnitude of segregation for each product cannot be explained for example by production run size, but are caused by size variations in the silo input, uneven distribution of fines over the heap surface during filling, unpredictable stagnant zones during discharge, and sampling procedure. Segregation at discharge mainly increases with increasing particle size distribution, but the product with the widest size distribution does not segregate the most. The width of the particle size distribution for the products correlates with the mass fraction of fine particles, and inclusion of a special additive (synthetic fibers) in very small proportions is also seen to affect segregation. Therefore, a regression model based on the mass fraction of fines and fibers was employed to organize the products according to the magnitude of segregation. Results for the model show that segregation does not always increase with an increase in the width of the particle size distribution and is negatively affected by inclusion of light and elongated particles (fibers).

show abstract

Section: Preliminary Testsmentioning

confidence: 95%

“…14 Segregation at discharge occurs mainly because the material is unevenly distributed over the silo's cross section during filling as a result of the embedding, fluidization, and aircurrent mechanisms. 15 Designing the silo to give mass flow may not entirely eliminate segregation at the end of the emptying process. 16 1.3.…”

Section: Introductionmentioning

confidence: 99%

Analysis of Segregation Data for a Dry Mineral-Based Construction Materials Plant

Engblom

Saxén

Zevenhoven

et al. 2012

Ind. Eng. Chem. Res.

View full text Add to dashboard Cite

show abstract

“…This condition is known as ‘core flow’ or ‘funnel flow’ and frequently leads to pockets of non-flowing material stagnating at the hopper wall near the outlet [3]. Material within these stagnant zones is typically the last to exit the hopper [4]. Ideally, material ‘first in’ will also be ‘first out’, ensuring that it can be reliably tracked and not jeopardize quality or safety.…”

Section: Introductionmentioning

confidence: 99%

“…This has been theorized to result from an imbalance of forces pushing larger particles upwards as smaller particles fill the voids below them [5]. The degree of segregation is influenced by many factors, primarily particle size ratio, and differences in shape and density, while the mechanism of segregation is related to the absolute particle sizes in the mixture [4,6,7].…”

Section: Introductionmentioning

confidence: 99%

Granular size segregation in silos with and without inserts

et al. 2021

View full text Add to dashboard Cite

The storage of granular materials is a critical process in industry, which has driven research into flow in silos. Varying material properties, such as particle size, can cause segregation of mixtures. This work seeks to elucidate the effects of size differences and determine how using a flow-correcting insert mitigates segregation during silo discharge. A rotating table was used to collect mustard seeds discharged from a three-dimensional (3D)-printed silo. This was loaded with bidisperse mixtures of varying proportions. A 3D-printed biconical insert was suspended near the hopper exit to assess its effect on the flow. Samples were analysed to determine the mass fractions of small particle species. The experiments without the insert resulted in patterns consistent with segregation. Introducing the insert into the silo eliminated the observed segregation during discharge. Discrete element method simulations of silo discharge were performed with and without the insert. These results mirrored the physical experiment and, when complimented with coarse graining analysis, explained the effect of the insert. Most of the segregation occurs at the grain–air free surface and is driven by large velocity gradients. In the silo with an insert, the velocity gradient at the free surface is greatly reduced, hence, so is the degree of segregation.

show abstract

“…The structure of a hopper is simple, but the flow behavior of the particles inside is very complicated, which is very interesting. In the past few decades, segregation of particles in hoppers has attracted great attention from scholars. , Scholars have done a lot of research work on particle size segregation in hoppers by experiments and the discrete element method (DEM). − Geometric parameters, − particle properties, − and interaction parameters have significant effects on segregation, and there is obvious percolation on the free surface . Among them, DEM, as an effective method, has been widely used in the simulation of particle motion. − Some information that cannot be directly obtained in experiment can be obtained through DEM simulations.…”

Section: Introductionmentioning

confidence: 99%

Local Percolation of a Binary Particle Mixture in a Rectangular Hopper with Inclined Bottom during Discharging

et al. 2020

View full text Add to dashboard Cite

To reveal the local percolation characteristics of a binary particle mixture in a rectangular hopper with inclined bottom, the discrete element method (DEM) is used to simulate the discharging process. A local percolation evaluation method is proposed, and the percolation strength grid maps are drawn. The effects of geometric parameters, particle properties, and interaction parameters on percolation are investigated. Apart from the free surface, percolation is mainly concentrated near the wall and at the bottom. With the increase in the orifice width, the average local percolation strength index (ALPSI) of the near-wall region increases and that of the bottom region decreases. The effect of the angle on percolation in the near-wall region can be ignored. The effect of friction on local percolation is significant. Increasing the fine particle mass fraction and reducing the difference in particle size can effectively avoid percolation.

show abstract

Segregation of Construction Materials in Silos. Part 2: Identification of Relevant Segregation Mechanisms

Cited by 11 publications

References 13 publications

Analysis of Segregation Data for a Dry Mineral-Based Construction Materials Plant

Analysis of Segregation Data for a Dry Mineral-Based Construction Materials Plant

Granular size segregation in silos with and without inserts

Local Percolation of a Binary Particle Mixture in a Rectangular Hopper with Inclined Bottom during Discharging

Contact Info

Product

Resources

About