A1 Journal article (refereed), original research

Study on the filtration characteristics of green liquor dregs

Publication Details
Authors: Golmaei Mohammad, Kinnarinen Teemu, Jernström Eeva, Häkkinen Antti
Publisher: Elsevier
Publication year: 2017
Language: English
Related Journal or Series Information: Chemical Engineering Journal
Volume number: 317
Start page: 471
End page: 480
Number of pages: 10
ISSN: 1385-8947
eISSN: 1873-3212
JUFO-Level of this publication: 2
Open Access: Not an Open Access publication


Separation of dregs from green liquor is a major challenge in kraft pulp mills, and it results in compressible

filter cakes with high specific cake resistance. In industrial applications, the use of lime mud as a filter

aid is a practical approach to reduce the resistance of the dregs cake. However, the amount of solid waste

then increases considerably, because the lime mud has to be disposed with the dregs. In this study, green

liquor sludges from two different pulp mills were filtered without filter aids by using laboratory-scale

pressure filters. The effect of some variables, such as the permeability of the filter cloth, the temperature

of filtration, the filtration pressure, and the storage period on the filterability of the green liquor sludges

was investigated. The results provide information for optimizing the process parameters to improve the

filterability of the sludge. The lowest cake resistance (2.20 1012 m/kg) was obtained at filtration the temperature

of 80 C. However, the higher operating temperature did not necessarily have a positive effect on

the recovery of sodium (valuable element for the process) from the cake. The results showed that higher

amounts of certain elements, such as Na, K and B were recovered from the dregs cake at the filtration

temperature of 60 C. It was also observed that the storage period had a negative effect on the filtration

properties. In addition, elemental analysis of the filtrate and dregs cake samples showed that harmful

metals, such as Al, Cd, Fe, Mn and Zn were mostly insoluble and remained in the dregs.

Research Areas

LUT Focus Areas

Last updated on 2018-19-10 at 07:55