Application of the Discrete Element Method to Study the Effects of Stream Characteristics on Screening Performance

Vibrating flip-flow screens (VFFS) are widely used to separate high-viscosity and fine materials. The most remarkable characteristic is that the vibration intensity of the screen frame is only 2–3 g (g represents the gravitational acceleration), while the vibration intensity of the screen surface can reach 30–50 g. This effectively solves the problem of the blocking screen aperture in the screening process of moist particles. In this paper, the approximate state of motion of the sieve mat is realized by setting the discrete rigid motion at multiple points on the elastic sieve mat of the VFFS. The effects of surface energy levels between particles separated via screening performance were compared and analyzed. The results show that the flow characteristics of particles have a great influence on the separation performance. For 8 mm particle screening, the particle’s velocity dominates its movement and screening behavior in the range of 0–8 J/m2 surface energy. In the feeding end region (Section 1 and Section 2), with the increase in the surface energy, the particle’s velocity decreases, and the contact time between the particles and the screen surface increases, and so the passage increases. When the surface energy level continues to increase, the particles agglomerate together due to the effect of the cohesive force, and the effect of the particle’s agglomeration is greater than the particle velocity. Due to the agglomeration of particles, the difficulty of particles passing through the screen increases, and the yields of various size fractions in the feeding end decrease to some extent. In the transporting process, the agglomerated particles need to travel a certain distance before depolymerization, and the stronger the adhesive force between particles, the larger the depolymerization distance. Therefore, for the case of higher surface energy, the screening percentage near the discharging end (Section 3 and Section 4) is greater. The above research is helpful to better understand and optimize the screening process of VFFS.

Section: The Dem Model Setting Of Vffsmentioning

confidence: 99%

A Numerical Study of Separation Performance of Vibrating Flip-Flow Screens for Cohesive Particles

Geng

Wang

2021

“…In the BPM, the mineral grains in a rock sample are represented by rigid spheres bonded at their contacts. This model has many applications from fundamental research on rock mechanics [24] to large-scale applications [25]. Potyondy and Cundall [26] first introduced the parallel BPM, which had a few shortcomings.…”

Section: Flat-jointed Bonded Particle Modelmentioning

confidence: 99%

Effect of Stress Path on the Failure Envelope of Intact Crystalline Rock at Low Confining Stress

Patel

Martin

2020

Numerical modelling is playing an increasing role in the interpretation of geological observations. A similar phenomenon is occurring with respect to the interpretation of the stress–strain response of intact rock measured in laboratory tests. In this research, the three-dimensional (3D) bonded particle model (BPM) with flat-jointed (FJ) contact was used to investigate the impact of stress paths on rock failure. The modified FJ contact model used for these studies numerically captured most of the intact rock behavior of Lac du Bonnet granite observed in the laboratory. A numerical simulation was used to track the behavior of this rock for different stress paths, starting with uniaxial tension and compression loading conditions. The migration from uniaxial tension to triaxial compression is challenging to simulate in physical laboratory tests but commonly observed around underground excavations. The numerical modelling methodology developed for this research tracks this stress path and the impact of the intermediate stress on peak strength at low confinements, commonly found around underground excavations.

“…It is affected by the relative difference among various properties such as particle shape, size distribution and material density. Davoodi et al [12] discuss the application of the discrete element method to study the effects of stream characteristics on the screening performance. Discrete element method is a method for analysing the interactions among individual particles and between particles and a screen deck in a controlled environment.…”

Section: The Special Issuementioning

confidence: 99%

Editorial for the Special Issue: “Physical Separation and Enrichment”

Farrokhpay

2020