-
wa=-5 -p
&&?77
ONTAMINANTS ENCOUNTERED IN WASHING AND FLOTATION
DElNKlNG PROCESSES A practical method for contaminant
analysis
BY T. MAH, F. REID, J. REYNOLDS, AND A. YAU
T. Mah, QUNO Corp., Thorold, ON.
4 F. Reid,
QUNO Corp., Thorold, ON.
UNO CORPORATION (formerly The Quebec and Ontario Paper Com- Q
pany), a wholly-owned subsidiary
of the Tribune Company of Chicago, is a major newsprint producer
in Canada. It has two newsprint mills, one in Thorold, ON, and one
in Baie-Comeau, QC. Total
newsprint production from these two mills amounts to about 830
000 tonnes per year(t/y).
In 1982, the Thorold mill was rebuilt and expanded in an
extensive modern- ization program. As the mill is far away from
wood sources and to take advan- tage of its proximity to the urban
forest in southern Ontario, a 230-t/d washing deinking plant was
installed as part of this modernization program.
At that time, the furnish to the paper machines consisted of 25%
washing deinked pulp, 15% sulphite, 15% CMP and 45% TMP. The waste
paper feed stock to the washing deink plant con- sisted of old
newspapers (ONP) only.
Again, in 1987, Thorold underwent another major modernization. A
500- t/d flotation deink plant was built and the washing deinking,
CMP and sulphite plants were shut down. This change allowed the
mill to expand the use of recycled fibres and take advantage of the
process flexibility provided by flota- tion deinking
technology.
Unlike the washing deinking system, flotation deinking can
handle both the ONP and magazines or coated paper. Presently, the
feed stock to the paper machine is about 25% TMP and 75% flotation
deinked pulp.
Over the past 10 years, our Thorold mill has had experience in
operating both washing and flotation deinking plants. As these
processes operate on different chemistries and use different types
of waste-paper feed-stock, the types of contaminants encountered in
their operation and present in the final deinked pulps are also
different.
This paper describes the types of con- taminants encountered in
these deink- ing processes and methods for their analyses.
OEINKING PROCESSES The following brief description of
the differences between these two deinking technologiey will
help explain why different contaminants are encountered.
The washing deinking process is essentially a laundry process.
First, the ink is detached from the waste papers by using deinking
chemicals, i.e. wetting agent and surfactant. The detached ink
particles are generally less than 10 pm and well dispersed in the
pulp slurry. These dispersed inks are removed from the pulp through
repeated dilution and thickening actions.
This washing technique is suitable for handling waste papers
with never- dried inks, i.e. ONP or old waste newspa- pers, which
do not form visible specks in the pulping step.
In the process, all other contami- nants present in the waste
paper feed stock are removed with conventional cleaning and
screening equipment. Fig- ure 1 shows the mechanism in the wash-
ing deinking process.
On the other hand, as shown in Fig. 2, the flotation deinking
process is based on ink agglomeration chemistry. After the ink is
detached from waste paper in the pulping step, the ink particles
are agglomerated by using a suitable collec- tor, e.g. fatty acid
soap. These agglomer- ates generally range from 30 to 100 pm in
size and are hydrophillic or water-lov- ing in nature. They would
remain in sta- ble suspension in the pulp slurry before the
flotation cell operation.
However, upon entering the flota- tion cells, the agglomerates
are modi- fied to become hydrophobic or water- repellent with the
addition of lime. In the flotation cells, these hydrophobic ink
agglomerates readily attach to the air bubbles and are discharged
as foam sludge.
The flotation deinking technique can handle both ONP and coated
waste papers, i.e. magazines, which form big- ger ink particles in
the pulping step.
52 PULP & PAPER CANADA 95:4 (1994) 4 T166
-
operation, the adhesives broke down into tidy but visible “dots”
which were gelatinous and tacky.
They could not be removed along with the ink in the washing
operation. Even though most of the stickies were removed in the
fine slotted screen and through-flow cleaner operations, some
remained in the final deinked pulp.
These stickies deposited on the paper machine wire, contributing
to light spots on paper and adversely affect- ing the paper quality
and paper ma- chine runnability. In flotation deinking: The major
con- taminants encountered in the flotation deinking process were
ink particles, stickies, hot melt, and specks. However, as shown in
Table 111, only particles and specks were the major contaminants
present in the final flotation pulp.
It was found that the flotation cells not only remove ink but
also stickies. As shown in Table IV, about half of the stickies
present in the pulp after the pulping step were removed in the
flota- tion cell operation. The flotation cells together with the
screening and clean- ing steps removed almost all of the stick- ies
in the deinking system.
Hot melt contaminants originated from the hot melt adhesives
used in the magazine bindings. In the pulping oper- ation, most of
the binding remained intact and was in the form of strips and
broken fragments.
They could be readily removed in the screening operation and
hence were not present in the final flotation deinked pulp
Most of the specks present in the flotation deinking process
originated from the use of ultra-violet (W) cured coating in the
magazines. Unlike the normal solvent-based varnish coating, the UV-
cured coating is based on poly- acrylate chemistry. In the deinking
pro- cess, this coating breaks down into small but visible specks
which cannot be effec- tively removed by the conventional screening
and cleaning equipment.
Hence, its presence in the coated waste paper or magazine
feed-stock would contribute to increased dirt con- tent in
flotation deinked pulp and final paper products.
As the ink removal efficiencies of the flotation cells will
never reach loo%, there will be some residual ink remain- ing in
the deinked pulp sent to the paper machines. The quantity of ink in
the pulp depends on the ink removal efficiencies of the flotation
cells.
- R6sumQ: La societe papetiere QUNO a de I’experience en fait
d’exploitation d‘ateliers de desencrage par flottation et par
lavage. Cette communication decrit les genres de produits de
contamination rencontres dans ces exploitations ainsi qu’une
methode pratique d’analyse des produits de contamination.
0 o NTAM w A N T AN A LY s E s To identify the types and
quantity of
contaminants present in the deinking operation requires
developing reliable and practical analytical techniques.
Washed Contaminants deinked pulp
Flotation deinked pulp
Ink Specks
Stickies
Hot melt
Yes
Very low Yes
Very low
Yes
Yes
Very low
Very low
Stickies content (No. count per 25 g od pulp)
After pulper
After flotation cell
After fine slotted screen
After through flow cleaners
20 10 7 3
Level
No. count per 25 g Contaminant od pulp Percent
Ink
Specks
Hot melt
Plastics
Stickies
Total
1 04 30 0.0
12 1
147
71 21 0.0 8.0 1 .o
100
However, there is not yet any standard The quantity of the
contaminants are method available for these applications determined
by image analysis and visual in the industry. To meet the needs in-
counting, whereas their types are found house analytical methods
were devel- by microscopic examination. oped at QUNO using infrared
micro- A technique employed at QUNO for scopy, imaging analysis and
light the contaminant analyses involves first microscopy
techniques. separating the contaminants from 25 od
Abstract: Quebec and Ontario Paper Company (now QUNO
Corporation) has experi- ence in operating washing and flotation
deinking plants. This paper describes the types of contaminants
encountered in these operations and a practical method for
contaminant analyses.
Reference: MAH, T., REID, F., REI”OLDS,J., YAU, A. Contaminants
encountered in wash- ing and flotation deinking processes. Pub
Paper Cun 95(4): T166-169 (April 1994). Paper pre- sented at the
79th Annual Meeting of the Technical Section, CPPA, at Montreal, QC
onJanuary 25 to January 29,1993. Not to be reproduced without
permission. Manuscript received Novem- ber 15, 1993. Revised
manuscript approved for publication by the Review Panel September
16, 1993.
Keywords: ANALYSIS, DEINKING, FLOTATION, IMPURITIES, WASHING,
DEINKED STOCK.
54 PULP & PAPER CANADA 95:4 (1994) 4 T168
-
48tipippita Annual General Conference .Melbourne, Australia (+61
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Apr. 30-May 4
TAPPI Coadng Coaftlreace W M Marriott Hotel, San Diego, CA
(404-446-1400) FIEPAG '94 - 13 Intl. Packing, Paper 8c Graphic Arts
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Regency, Vancouver, BC (G.D. Black, 5148666621)
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Washington, Washington, DC (C.Todd-Moffat, 708-9560250)
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(Lucie Veilleux, 514866-6621)
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; deinked pulp in a 0.004in. slot screen. 'he contaminates
retained on the creen are then dried on a filter paper nd examined
with the aid of a stereo nicroscope and a sharp stainless steel
robe.
As each contaminant responds differ- ntly to the contact of the
probe, they an be readily classified into different pes. The
content of each contaminant i expressed as number of count per 25 g
id gram of deinked pulp analyzed. Lesults of a typical flotation
deinked iulp contaminant analyzes using this xhnique are shown in
Table V.
The contaminant types classified by his technique were confirmed
by IR nalyses.
As the technique involves screening he deinked pulp through a
0.004 in. lot, contaminants smaller than 0.004 in. lr 100 pm in
diameter would likely pass hrough the screen and not be analyzed.
Iowever, contaminants of this size are ot visible and do not appear
to have any oticable effect on our paper machine peration and paper
quality.
Along with image analyzing which etermines the content but not
the type f the contaminants, this method has een successfully used
for contaminant nalysis in QUNO's deinking operations.
Contaminants encountered in the ulps from the washing and
flotation einking processes are different. The iajor contaminants
in the washing einked pulp are ink agglomerates and tickies while
in the flotation deinked ulp major contaminants are ink parti- les
and specks from the magazine coat- igs. This difference is
attributed to the ifferent waste papers used and methods mployed in
these deinking processes.
QUNO has developed practical and :liable in-house analytical
methods to uantify and classify the contaminants in i e deinking
processes and deinked ulp produced.-
Innovations Experiments Discoveries Technical papers keep you up
to date on the latest in industry research . Every month
T 169 4 PULP & PAPER CANADA 95:4 (1994) 55
-
1994 INTERNATIONAL PULP BLEACHING CONFERENCE Hyatt Regency
Hotel, Vancouver, B.C., June 13-16,1994
Jcintlysponsaed bytheTechnicd Sedion, CPPA, TAPPI cndSPCI
t
PRELIMINARY PROGRAM
THE IMPACT OF BLEACHING ALTERNATIVES ON EFFLUENT CHARACTERISTICS
AND ENVIRONMENTAL IMPACT
TCF BLEACHING -TOWARDS HIGH STRENGTH, HIGH BRIGHTNESS AND COST
COMPETITIVENESS
Monday, June 13 0830-1 200 1. "Biological and Chemical
Characterization of Effluent from a Bleached Kraft Mill before
and after Conversion to Increased Chlorine Dioxide
Substitution", T. HALL, L. LaFLEUR, R. HALEY and R. MINER
2. "Effluent Quality in Different Combinations of Bleaching
Sequences at Aracruz", M. MONTANHESE de LIMA, A.C. OLlVElRA FILHO,
A. WACKSLAVOWSKI and M.A. PEIXOTO
3. "On the Nature of High Molecular Weight Effluent Materials
from Modern ECF- and TCF-Bleaching", 0. DAHLMAN, A. REIMANN, L.M.
STROMBERG and R. MORCK
4. "A Comparison of Chlorinated Phenolic Compound Concentrations
and Loadings in Bleach Plant and Treatment System Samples at Eight
Mills", D.B. SPENGEL, B. BICKNELL, D.A. ANDERSON, M. SMITH and D.G.
BODIEN "Assessment of the Ecological Risks Associated with the Use
of Chlorine Dioxide for the Bleaching of Pulp", D.C. PRYKE, H.
BERGMAN, D. MACKAY, K. SOLOMON, R. HUGGET and B. McKAGUE
5.
ADVANCES IN CHLORINE DIOXIDE DELlGNlFlCATlON FOR LOW AOX
Monday, June 13 14001700 1. 2.
'The Evolution of Pulp Bleaching Practices at MB Harmac", D.J.
McKENZlE "Gas-Phase Chlorine Dioxide Delignification of Softwood
Kraft, Kraft-Oxygen, Poly- sulfide-AQ, and Polysulfide-AQ-Oxygen
Pulps for High Brightness and Ultra Low AOX", V.R. PARTHASARATHY
and G.F. RUDlE
3. "Process Modifications to Decrease Organochlorine Formation
during Chlorine Diox- ide Delignification", D.W. REEVE, K.M.
WEISHAR and L. LI
4. "Modified Modern ClO2-Bleaching", S. LJUNGGREN and E. BERGNOR
5. "Short Retention Time C102 Delignification for Improved Effluent
Quality: The Effect
of Reaction Time on the Characteristics of Whole Effluents and
Effluent Fractions from OD(E0) Bleaching of Softwood Kraft Pulp",
T.A. SCHWANTES and T.J. McDONOUGH "Chloride Ions can Decrease the
Formation of AOX in D and DC Prebleaching", A. TEDER and A.
TORNGREN
6.
OZONE BLEACHING
1.
2.
3.
4. 5.
Tuesday, June 14 0830-1 200 "Development and Progress in Ozone
Bleaching at the Skoghall Mill", R. HELANDER and G. BOHMAN "Pilot
Plant Bleaching with Ozone at High Concentration and Medium
Consistency, G. SACCIADIS, H. BARCLAY, R. BERRY, L. SHACKFORD, J.
ROUNSAVILLE, K. KASANO. V. MAGNOTTA and V. AYALA
Wednesday, June 15 0830-1200 1.
2.
3.
4.
5.
"Effective TCF Bleaching of Eucalyptus to Market Brightness",
D.R. LAZAR, C. FOELKEL and D.F. SEITER "TCF Bleaching of Industrial
Softwood Kraft Pulp to High Brightness with and without Ozone", J.
ODERMATT, R. PATT and 0. KORDSACHIA "TCF Bleaching of Softwood and
Birch Kraft Pulps to High Brightness - Sequences and Pulp Quality",
R. MALINEN, T. RANTANEN, R. RAUTONEN and L. TOIKKANEN
"OZP-Bleaching of Softwood and Hardwood Kraft Pulps to Full
Brightness", U. GERMGARD and S. NORDEN "Energy Efficiency in ECF
and TCF Bleaching", T. LAXEN and K. HENRICSON
NEW OXIDANTS FOR BLEACHING
Wednesday, June 15 1400-1530 1. "Activated Oxygen
(Dimethyldioxirane), a Selective Bleaching Agent for Chemical
Pulp Bleaching, IV: A Successful Pilot Trial and Process Designs
for an Industrial Application", C.-L. LEE, R. HOGIKYAN, J.T.
WEARING, A. SKOTHOS, G. SAC- CIADIS, C.W. OLOMAN, B. AMINI, W.W.
TEETZEL, P. FETISSOFF, L. TENCH and S. HARPER "Totally
Chlorine-Free Bleaching with Dimethyldioxirane", T.J. McDONOUGH, A.
MARQUIS and A.J. RAGAUSKAS "Persulphate Bleaching of Softwood Kraft
Pulp", A. WONG, S. WU, C. CHlU and J. ZHAO
2.
3.
POSTER SESSION
Wednesday, June 15 (approximately 45 poster presentations)
1530-1830
DECRE~SING BLEACH PLANT EFFLUENT - TOWARDS SYSTEM CLOSURE
Thursday, June 16 0830-1 200 1.
2.
"Closing up a TCF Bleach Plant", L. AHLENIUS, C-J. ALFTHAN, L.
UHLIN and E. WIKBERG "A German Closed Cycle Sulfite Mill -
Development and Implementation", N. NIM-
3.
4.
MERFROH, H.U. SUSS, H-P. BOETTCHER and W. LUTTGEN "Effect of
Dissolved Organic Material from Various Sources on the Efficiency
and Selectivity of MC Ozone Bleaching", E. HALINEN, C.-A. LINDHOLM
, J. GULLICHSEN and K. HENRICSON "Bleach Plant Close-up and
Conversion to TCF: A Case Study Using Mill Data and Computer
Simulation", T.R. BROOKS, L.L. EDWARDS, J.C. NEPOTE and M.R.
"Pilot Plant Experience with Ozone in TCF Bleaching of Eucalypt
Pulp", A. MOKFIEN- SKI and B.J. DEMUNER "Studies of Ozone
Delignification of Oxygen Bleached Pulps", L.B. SONNENBERG
ccMinimizing Strength Degradation during Totally Chlorine-free
Bleaching including an Ozone Stage", C. CHIRAT and D. LACHENAL
CALDWELL 5. "A New Process toward Bleach Plant Closure", G.
MAPLES, R. AMBADY, S. STRAT-
TON, R. CARON and R.V. CANOVAS 6. "Strategies for Metal Removal
Control in Closed Cycle Mills", H. LINDBERG, H.
ENGDAHL and R. PUUMALINEN
ADVANCES IN PEROXIDE BLEACHING - SYSTEM CLOSURE, THE NEXT
GENERATION OF ENZYME BLEACHING METAL MANAGEMENT AND HIGH
PERFORMANCE
Tuesday, June 14 14001700 1. "Oxidative Bleaching Enzymes; the
Next Generation?", M.G. PACE, R. BOURBON-
NAIS, F. ARCHIBALD, I.D. REID and L. JURASEK 2. "Biobleaching
Process Using Hyper Lignolytic Fungus, Strain IZU-154 and its
Mutants", M. KAKEZAWA 3. "Role of Pulp Metal Profile on
Enzyme-Aided TCF-Bleaching", J. BUCHERT and L.
VllKARl 4. "Novel Enzyme Treatment for Dioxin-Free Bleaching of
Kraft Pulp with High Kappa
Factor and Low C102 Substitution", J.S. TOLAN and B.E. FOODY 5.
"Microscopic and Chemical Examination of the Effect of Treating
Unbleached Soft-
wood Kraft Pulp with Hemicellulase Enzymes", X. YU, J.L. MINOR,
R.H. ATALLA, M.M. LABBAUF and R.L. FARRELL
Thursday, June 16 1400-1700 1,
2.
3.
2.
3.
"Improvement of the Chelating Stage in aTCF Sequence when
Closing up the Bleach Plant", 0. LINDEBERG "Metal Management in
TCF/ECF Bleaching", J. BASTA, L. HOLTINGER and P. LUNDGREN "A
Comparison between Acid Treatment and Chelation prior to Hydrogen
Peroxide Bleaching of Kraft Pulps", J. BOUCHARD, H.M. NUGENT and
R.M. BERRY "Pressurized Peroxide Bleaching of Kraft Pulp - Can
Fully Bleached TCF Pulp Be Produced in One Stage?", R. SZOPINSKI,
"Behaviour of Residual Lignin in Kraft Pulp during Bleaching", D.
LACHENAL, J.C. FERNANDEZ and P. FROMENT
I I For further information please contact Glen Black, Technical
Section, CPPA, 1155 Metcalfe St., Suite 1900,
Montreal, Quebec H3B 4T6, Canada: Telephone: (514) 866-6621,
Fax: (514) 866-3035 L I
