SLIDE 1 by Yves Dionne - Bowater, Gatineau (Qc) Michelle Ricard - FPInnovations, Paprican, Pointe-Claire (Qc) Gilles Dorris - FPInnovations, Paprican, Pointe-Claire (Qc) Claude Daneault - CIPP/ UQTR, Trois-Rivières (Qc)
Flotation Column: A Process Unit for Cleaning Up Papermachine Whitewater Circuits
SLIDE 2 W hitew ater Circuit
Source: Bonin, J. ( 1 9 8 8 )
SLIDE 3 Problem atic
Loss of brightness on the paper machine which
amplifies during Summer
Generates
loss
- f production time, higher
rejects rate, higher freshwater consumption, loss
- f quality, increase
- f bleaching
cost, delays in delivering paper to our customers, insatisfaction of customers and higher level of stress to the employees.
This
brightness loss is estimated at 1.365M $Cnd.
SLIDE 4 Paper Machine No 6
Beloit Bel-Form Installed in 1967 Rebuilt in 1993 9,1 m width 980 m/ min 180,000 ADMT/ y
SLIDE 5
Brightness Loss PM6
SLIDE 6
Problem Analysis
After many cycles of recirculation,
fines lose brightness, are tainted by repeated dye applications, and are contaminated in extractives, micro- stickies and metals.
SLIDE 7
Solution
Improve fines management by incorporating a treatment process:
Cleaning? Retaining? Flushing?
SLIDE 8
Proposed solution
Installation of a flotation column at
the wire pit in order to clean up the papermachine whitewater circuits.
SLIDE 9
Flotation colum n
Technology from the mining industry Limited success in the P&P industry
(Kvaerner Hymac Inc - 11 installations around the world in 2006)
Always aimed to replace conventional
flotation technology
SLIDE 10 Flotation colum n
ACCEPTS AIR FEED W ASH W ATER REJECTS
Froth Zone Collection Zone
SLIDE 11
Our goals
Higher fines brightness in the wire pit
= brighter paper
Fines less sticky = Cleaner Paper
Machine = Higher runnability
Lower fresh water consumption =
Lower fibre loss to sewer
Reduction in overall chemicals
SLIDE 12 PRELI MI NARY TRI ALS
Conventional lab flotation unit
PM6 Feed Accepts- No chemistry Rejects – No chemistry Accepts – 0.05 % surfactant Rejects – 0,05 % surfactant Consistency (%/o.d.) 0.381 N.D. N.D. N.D. N.D. Brightness (ISO) 53.87 57.08 41.37 58.28 40.91 L 79.26 81.38 70.47 82.37 69.9 a* 1.26 1.12 1.95 0.69 1.97 b* 2.07 2.58 0.40 3.28 0.22 ERIC value 264.8 172.6 904.5 117.4 930.0 Ash (%) 17.6 N.D. N.D. N.D. 35.2
N.D. Not determined
SLIDE 13 Flotation colum n
diam etre 1 0 ,2 cm height 4 ,6 5 m
SLIDE 14 Characteristics - PM w hitew ater silo
Table I. Characteristics of mill whitewater sam ples. Type of whitewater Silo M ill Product Newsprint DIP, % 50 TM P, % 50 Consistency, % 0.53 Ash Content, % 15.2 ISO Brightnessa, % 56.1 ERIC
a, ppm
195 DCM Extractivesa, % 2.1
a M
easured on handsheet of fines
SLIDE 15 I m pact on extractive m aterials
3 6 0.0 0.5 1.0 1.5 2.0 2.5
Flotation Time, min DCM Extracts, % (w/w)
SLIDE 16 I m pact on ink rem oval
3 6 50 100 150 200 250
ERIC, ppm Flotation Time, min
SLIDE 17 I m pact on brightness
3 6 54 55 56 57 58 59
Flotation Time, min Brightness, %
SLIDE 18
Brightness gain + 1 .8 %
Feed 5 6 ,1 % Accepts 5 7 ,9 % Rejects 4 1 ,2 %
SLIDE 19 Changes in particle size
0.1 1 10 100 1000 2 4 6
Fee d Acce pt Reje ct
Particle Diameter, µm Frequency, % of Volume
SLIDE 20 Evolution of m ean particle size
1 2 3 4 5 6 10 20 30
Accepts Rejects
Flotation Time, min Mean Particle Diameter, µm
SLIDE 21
Conclusion ( 1 )
Total extractives reduction up to 85 % Ink removal up to 64 %
Brightness lift of 1.8 points Column flotation removes selectively
the smallest fines/ filler that are the most hydrophobic
Longer flotation time increases
performance but also increases material loss
SLIDE 22
Conclusion ( 2 )
Selective removal of lipophilic material leads to a cleaner paper machine whitewater circuit with potentially improved optical and strength properties of paper.
SLIDE 23
Acknow ledgem ent
Management, BOWATER Gatineau FPInnovations, PAPRICAN
Christine Lapointe Nathalie Pagé Yuxia Ben
EKA Chemicals
SLIDE 24
