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Oulun yliopiston väitöskirjat

UTILISATION OF TUBE FLOW FRACTIONATION IN FIBRE AND PARTICLE ANALYSIS, ACTA UNIVERSITATIS OULUENSIS C Technica 382

ISBN-13:	978-951-42-9448-8
Kieli:	englanti
Kustantaja:	Oulun yliopisto
Oppiaine:	Tekniikka, matematiikka
Painosvuosi:	2011
Sidosasu:	pehmeäkantinen
Sijainti:	Print Tietotalo
Sivumäärä:	108
Tekijät:	LAITINEN OSSI

21.50 €

The tube flow fractionation method used in this thesis is one of the field flow separation processes,which can be used to fractionate particles over the entire size range of pulp particles (1–5000 µm)with high selectivity. The classification of particles in different size categories enables thefractional analysis of samples. According to this thesis, particle length is the most significantindividual shape factor in particle classification for different size categories using tube flowfractionation. The fractional approach investigated in this thesis offers an interesting tool for investigatingdifferent pulp types more thoroughly than many other conventional laboratory methods such asthe Bauer-McNett classification of pulp or the hyperwashing of DIP samples. The tube flowfractionator can be used to replace the Bauer-McNett device to determine the mass percentages ofpulp sample fractions. Furthermore, pulp fractionation can be done quickly with the tube flowfractionation method and the results achieved are also comparable to the Bauer-McNettclassification. The utilisation of recycled raw material in paper production is likely to continue to increase inthe near future. This fact leads to even more heterogeneous raw material becoming one of themajor challenges in deinked pulp production. Changes in the quality of raw material such as ageor paper type have a notable effect on the deinkability of pulp. This creates a need to develop newmethods for measuring DIP properties; in particular, information about the ink-releasing rate andink particle size would be useful in controlling the deinking process. If DIP is fractionated withtube flow fractionation, it is possible to study the ink size distribution and ink content inside eachfraction, thus obtaining fractional information on the ink release rate and ink particle size. A comparison of different DIP raw materials and process solutions can be performed with thefractional analysis presented in this thesis. It was noticed that aging had a negative effect on theslushing rate of LWC and SC raw material, but not on ONP. The ink detachment of LWC and SCwas poorer when furnishes aged. However, the aging of LWC and SC did not result in a significantfragmentation of ink particles. In contrast, strong ink fragmentation is typical of aged ONPfurnishes. The fractional approach gives new insight into deinking mechanisms, and could beessential for finding optimal deinking process conditions, for example in a pulping process orflotation environment. The method would also enable enhanced control of different DIP processstages and would contribute to creating a more efficient process with better waste management andimproved final product quality.

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