Experimental Results for the Settling Behaviour of Particle-Fiber Mixtures

Abstract

Sedimentation of organic fibres and inorganic particles can be observed in several industrial applications. Fibres are involved not only in wastewater treatment but also in other separation applications. In the paper industry, the separation of inorganic filler and coating particles from short cellulose fibres is still a challenge in the recycling process. During that process, particles have to be removed to obtain a purified fibre suspension. These fibres can be used again to produce new paper. With the currently applied techniques, like screening and flotation, the efficiency of short fibre separation is very poor. Moreover, also separation by sedimentation fails due to similar settling velocities of heavy-small particles and the light and larger fibres. This paper concentrates on the sedimentation of organic fibres and inorganic particles in water. The investigated suspensions are made by resolving two different and specially produced papers a coated and an uncoated one, as well as the single components used for its production. We observe a different sedimentation behaviour according to the concentration of fibres and particles in the suspension and the pHvalue of it. The main result is that, according to the fibre rate, the sedimentation behaviour is particle dominant or fibre dominant.

The Stokesian Dynamics Method and the Settling behaviour of Particle‐Fibre‐Mixtures

“…Feist et al [10] investigates experimentally the separation behaviour of screened fibre suspensions. Their main result was, depending on the fibre to particle ratio the separation behaviour is dominated by the alignment and clustering of the fibres.…”

“…But hardly any experiments can be found with fibre-particle suspensions. Feist et al [10] investigates the settling behaviour of screened paper suspensions. They found out that depending on the particle to fibre ratio in the suspension an alignment and clustering of the fibres dominates the settling.…”

Sedimentationsuntersuchungen zum Trennverhalten von Faser‐Partikel‐Suspensionen

“…Erste Ergebnisse der Versuche wurden bereits in Feist et al [8] ausführlich diskutiert. Versuche mit der Sedimentationswaage lieferten das Ergebnis, dass die Sedimentationsgeschwindigkeitsverteilung des ungestrichenen Papiers unabhängig von der Feststoffkonzentration monomodal ist.…”

Stokesian dynamics and the settling behaviour of particle–fibre‐mixtures

“…Harlen et al (1999) made experiments with a big sphere in a fibre suspension and established that the drag coefficient of the sphere has a dependence on the concentration of the fibres. Finally, Feist et al (2007) showed by experiments with particle-fibre suspensions, gained from recycled paper filtrate, that there is a dependence of the sedimentation velocity distribution on the pH-value and the concentration. But their main result was that the sedimentation is significantly effected by the fibre portion in the suspension.…”

“…But hardly any experiments can be found with fibre-particle suspensions. Feist et al (2007) investigates the settling behaviour of screened paper suspensions. They found out that depending on the particle to fibre ratio in the suspension one can observe an alignment which dominates the settling.…”