Segregation of Construction Materials in Silos. Part 1: Experimental Findings on Different Scales

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

doi:10.1080/02726351.2011.553880

Cited by 8 publications

(15 citation statements)

References 2 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Prescott et al 10 claim that such fluidization tests can reveal the tendency for a powder mixture to segregate vertically by accumulating fines to the surface layers of the bed in silos filled pneumatically or with free fall. However, the results for our previous investigations 14,15 imply that side-to-side or horizontal segregation with a surplus of fine particles at the walls of a centrally filled silo most likely occurs for both products tested here.…”

Section: Preliminary Testscontrasting

confidence: 50%

“…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: 96%

“…Four of the commercial products included in this work were also included in a sampling campaign performed during normal production conditions for the surge silo shown in Figure 5. In this previous work, 14 bags of final products were picked from the conveyor belt between filling spouts and palletizer throughout the discharging process. These bags were filled from the middle outlet/spout of the surge silo, and their size compositions were determined by sieving.…”

Section: Segregation Datamentioning

confidence: 99%

“…Figure 7) as reported previously. 14,15 Segregation at filling is caused by embedding, fluidization, and air-current effects. The mass fraction less than 125 μm gives the best indication of segregation.…”

Section: Segregation Datamentioning

confidence: 99%

“…Even though many construction materials induce the same segregation pattern, the magnitude of segregation at the end of complete discharge from a specific silo clearly depends on certain material properties such as the particle size distribu- tion. 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.…”

Section: Introductionmentioning

confidence: 99%

See 4 more Smart Citations

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 Testscontrasting

confidence: 50%

Section: Preliminary Testsmentioning

confidence: 96%

Section: Segregation Datamentioning

confidence: 99%

Section: Segregation Datamentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations