Recycling the fibres on tetra pak cartons - Eko paket

R e c y c l i n g t h e F i b r e s o n
T e t r a P a k C a r t o n s
Mario Abreu
Tetra Pak Canada Inc.
Dec. 20, 2000

Index
Chapter
Page
I. Introduction 03
II. Why Recycle? 03
III. Fibres 05
Pulp Processing / Mechanical Processes / Semichemical processes /
Chemical processes/ Boards made for Tetra Pak/ Bleaching / Wet
Strength / Multi-ply boards
IV. Waste paper recycling 09
Pulping/ Screening/ Centrifugal Cleaning/ Refining/ Washing /
Systems
V. <strong>Recycling</strong> cartons 19
TBA, TFA, TWA, TPA/ TR/ TB, TT
Mixed cartons
VI. Existing systems (selection) 23
Atlantic/ Crown/ Fiskeby/ Klabin/ Orebro/ Papeles Nacionales/ Scott
Feldmuhle/ Turkey trials
VII. Bibliography 33
Annex I. Trials at Black Clawson (96) 34
Annex II. Trials at Celleco (98) 39
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I - Introduction
The main purpose of this paper is to give enough knowledge for Tetra Pak employees to
approach paper mills and discuss recyclability of Tetra Pak’s cartons.
In order to achieve this goal, this paper has two main parts. Chapters I to IV focus on
general papermaking, which aims to show how paper is actually made and recycled, and
is meant to be a reference for Tetra Pak employees working with environmental affairs.
Chapters V and VI, as well as <strong>the</strong> Annexes I and II, are specifically related to Tetra Pak
cartons and besides being used inside Tetra Pak, <strong>the</strong>y can be provided to paper mill
contacts as background information. The message is clear that recycling Tetra Pak’s
cartons is totally based on existing technology and machinery.
Technologies for <strong>the</strong> recovery of residuals from <strong>the</strong> papermaking process are not
included here. It can be found, though, on o<strong>the</strong>r papers.
II - Why Recycle (Paper) ?
Replacing mechanical pulp, 1,000 kg of waste paper will preserve approximately 2 m 3 of
wood, or some 150 m 2 of forest. Replacing chemical pulp, 1,000 kg of waste paper
preserve approximately 4 m 3 of wood, or some 300 m 2 of forest.
World-wide, over 95 million (1996 data) tons of paper are recovered each year, but this
is still just one third of all total fibre used. According to <strong>the</strong> American Forest and Paper
Association, in <strong>the</strong> US in 1987, some 50% of all paper products produced were
landfilled, and just over 20% were recovered. In 1997, landfilling was under 30% and
recovering over 40%.
Figure 1.Comparison among papers recovered for recycling and landfilled. (Source AFPA, 2000)
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In 1998, Canada consumed 4.7 million tons of waste paper, from which 2.2 million were
imported. Although recycling capacity has doubled in that country between 1990 and
1998, still only 22% of <strong>the</strong> papers made in Canada are made from recycled <strong>fibres</strong>.
Paper <strong>fibres</strong> can be <strong>the</strong>oretically recycled 6 to 7 times. Therefore a 1,000 kg of virgin
pulp <strong>fibres</strong> can generate up to 6,000 or 7,000 kg of various kinds of paper, through
successive recovery and recycling operations. Fibres will loose some of <strong>the</strong>ir properties
every time <strong>the</strong>y are recycled, as <strong>the</strong>y are repeatedly subject to pulping, refining, drying
and so on, leading to lower value papers. Blending recycled and virgin <strong>fibres</strong> is an option
and an opportunity for paper mills to develop market niches.
Ano<strong>the</strong>r relevant factor to be considered is energy. The production of paper from trees
is energy intensive. Values change a lot due to production ranges, types of trees, types
of processes, types of papers etc, but figures from 26 to 45 GJ are well accepted as a
total energy consumption (heat and work) per ton of paper manufactured from trees.
Considering paper made from recycled paper, comparable numbers would be 7 to 15, or
approximately 3 to 4 times less energy consuming.
In a big conservation effort, paper mills in <strong>the</strong> US are currently using recovered old
corrugated containers (OCC) to manufacture over 50% of all new paperboards in <strong>the</strong>
market. Old newsprint (ONP) is only approximately 17% of <strong>the</strong> supply for new
newspaper. Only 10% of high-grade <strong>fibres</strong> are recovered for <strong>the</strong> manufacturing of high
quality deinked papers.
Anyway, <strong>the</strong> demand for recycled <strong>fibres</strong> will increase for <strong>the</strong> production of highest
quality papers in <strong>the</strong> future. The regulations for papers with increasing levels of postconsumer
content will increase paper manufacturer’s concern for <strong>the</strong> implementation of
high quality systems and processes, while <strong>the</strong>ir suppliers will have to develop smoo<strong>the</strong>r
(and more effective, at same time) mechanical and chemical processes. Recycled <strong>fibres</strong>
are generally weaker than virgin <strong>fibres</strong>; <strong>the</strong>y have decreased bonding capabilities, higher
amounts of fines and fibriles and require streng<strong>the</strong>ning adhesives.
Data from 1995 states that only 30% of all trees cut in <strong>the</strong> US were used for paper
manufacturing, whereas 45% were used for lumber products and 20% as fuel. 55% of
all wood used for papermaking, however, was comprised of chips and sawmill dust and
residuals, which are waste products for <strong>the</strong> lumber industry. Therefore, <strong>the</strong> paper
industry is not only promoting recycling, but also trying to cut less trees as possible and
doing so reducing <strong>the</strong>ir footprint on Earth.
1,000 kg of paper recovered will save approximately 2.5 m 3 (equivalent to 2,500 litres)
of landfill.
Tetra Pak cartons were minded to save more than <strong>the</strong>y cost. Making paper from Tetra
Pak cartons is just ano<strong>the</strong>r way of saving natural resources.
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III - Fibres
Pulp Processing
The process of papermaking from wood can be done in a large amount of different
ways. These processes though are normally under 3 independent classes: chemical,
semichemical (or chemimechanical) and mechanical, and identified by <strong>the</strong> way <strong>the</strong> <strong>fibres</strong>
are extracted from <strong>the</strong> trees, if this coarse language can be used for very complex
systems. The original mechanical process is to extract <strong>fibres</strong> by attrition. Temperature
can be used to easy <strong>the</strong> process. Or chemicals can be used to make it even easier, when
we have a chemimechanical or semichemical process. Or chemicals can be <strong>the</strong> main
reaction and <strong>the</strong>n <strong>the</strong> process is called chemical. It’s obvious that as much chemicals
you use for separation of <strong>the</strong> <strong>fibres</strong>, more of <strong>the</strong> resins that hold <strong>the</strong> fibre toge<strong>the</strong>r are
lost, as <strong>the</strong>y are attacked by <strong>the</strong> chemistry and <strong>the</strong>refore <strong>the</strong> yield goes down, at <strong>the</strong>
same time that <strong>the</strong> final quality goes up.
The chemistry of wood cells is <strong>the</strong> subject of series of books and impossible to
summarise in this paper. It is important, however, to understand that final properties of
paper such as brightness, strength, tear strength, elongation, stiffness, hygroinstability,
sheet consolidation, freeness etc. are related to both <strong>the</strong> origin of <strong>the</strong> fibre (tree
species) and to <strong>the</strong> way <strong>the</strong> <strong>fibres</strong> were “obtained” from <strong>the</strong> trees.
Mechanical processes
Fibres are extracted from cut trees by attrition, generally by <strong>the</strong> action of a stone
spinning against wood, under a continuous flow of water. The original process, usually
called SGWP or just GP (stone groundwood pulp) was improved by <strong>the</strong> addition of
pressure, by heating, or both, generating process like TRMP (<strong>the</strong>rmorefiner mechanical
pulp) and TMP (<strong>the</strong>rmomechanical pulp).
The yield of <strong>the</strong> mechanical processes (amount of pulp generated divided by amount of
wood processed) is generally between 95 and 98%.
Figure 2. Cut and debarked tress being attacked by a stone
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Semichemical or chemimechanical processes
There are several ways to process wood doing a chemical treatment prior to
mechanically extract <strong>fibres</strong>. Those processes have names such as CMP
(chemimechanical pulp); CTMP (chemi<strong>the</strong>rmomechanical pulp); CRMP (chemirefined
mechanical pulp) and so on. Processes such as NSSC (neutral sulfite semichemical pulp)
are usually called semichemical, mostly because <strong>the</strong> properties of <strong>the</strong> pulp vary from
those mentioned before, which are called chemimechanical by some authors.
The chemical pre-treatment removes part of <strong>the</strong> lignin and of <strong>the</strong> hemi-cellulose,
reducing <strong>the</strong> bonding of <strong>the</strong> <strong>fibres</strong>, thus facilitating <strong>the</strong> mechanical extraction.
Yields of such processes vary from 65 to 92%.
Chemical processes
Are those where an aqueous alkali solution is used to process vegetable pulp
<strong>fibres</strong>. The most used process is <strong>the</strong> one called sulfate, due to <strong>the</strong> use of NaSO4,
which is reduced to NaS, <strong>the</strong> “digesting” element. The sulfate (or Kraft) process
can handle a wide range of different types of woods and allow pulp to be
bleachable to a very high degree.
Chemical processes require large systems for <strong>the</strong> recovery of <strong>the</strong> chemicals from <strong>the</strong>
called liquors and treatment of waste.
Some advantages of this process are: can handle several wood species without
significant changes; higher capacity; high achievable fur<strong>the</strong>r bleaching and high fibre
quality.
Yield of such processes, however, is very low, in <strong>the</strong> range of 40 to 65%.
100%
Groundwood
CTMP Sulfite
NSSC
Unbleached Sulfate
Bleached Sulfate
3
75%
50%
25%
0%
2
1
0
Yield (%)
x10^6 fibers /gram
Figure 3. Comparison of pulp processing, on yield and density
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Processes used for manufacturing board for Tetra Pak
Fibres used for Tetra Pak’s cardboard are normally from two different processes, <strong>the</strong>
kraft (chemical) process, due to high quality of <strong>the</strong> fibre and <strong>the</strong> CTMP
(chemitermomechanical) process, due to <strong>the</strong> stiffness and yield delivered.
CTMP is produced by modest chemical impregnation, performed during <strong>the</strong> steaming
stage to explore bonding properties.
Kraft pulps are very good for recycling operations, and once Tetra Pak cartons are made
of virgin kraft, <strong>the</strong>y are a reliable source of high quality secondary <strong>fibres</strong>.
<strong>Recycling</strong> CTMP affects negatively <strong>the</strong> water retention capacity. This can be
noticed at <strong>the</strong> very first time <strong>the</strong> <strong>fibres</strong> are recycled, and <strong>the</strong> loss can be close to
50%. Bonding potential is also affected when CTMP <strong>fibres</strong> are recycled.
Hardwood CTMP is a good raw material for tissue papers, due to its considerable
stiffness properties associated to high water retention capacity, although not for
high quality tissue, due to <strong>the</strong> lack of whiteness. However, recycled CTMP will
not be considered a good raw material for tissue, as <strong>the</strong> water retention capacity
goes down, freeness goes up, bonding is decreased and <strong>the</strong> lignin has a trend to
go yellowish <strong>the</strong> more exposed to light it is.
Bleaching
As mentioned before, chemical processes are <strong>the</strong> ones most suitable for bleaching,
although it’s possible to bleach all kinds of pulp. In spite of being <strong>the</strong> most bleachable,
unbleached chemical pulp is darker than <strong>the</strong> o<strong>the</strong>rs are. Once considered <strong>the</strong> best
bleaching agent, Chlorine is been banned from <strong>the</strong> pulp mills due to environmental
concerns. Nowadays several pulp mills do <strong>the</strong> bleaching as successive reactions among
<strong>fibres</strong> and chemical elements, mainly NaOH, H 2 O 2 , O 2 and O 3 .
Boards manufactured for Tetra Pak usually have multi-layers of paper, being at least <strong>the</strong>
outer one manufactured from bleached <strong>fibres</strong>. For some markets, such as North
America, most cartons are made from 100% bleached <strong>fibres</strong>. Tetra Rex® cartons are
also generally manufactured only from bleached <strong>fibres</strong>.
Wet strength
Properties of paper can be modified by <strong>the</strong> use of chemicals during <strong>the</strong> actual paper
manufacturing as well.
Normal paper is characterised by an almost complete loss of strength when wet.
Polyaminoacid epichlorohydrin, urea-formaldehyde and melamine resins are
commercially available, from several chemical industries, under different trade names, to
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increase paper resistance to wet environments. Fibres are treated with those chemicals
during papermaking under manufacturer’s technology and background, but <strong>the</strong> final
cure generally takes place on <strong>the</strong> machine dryers, which provides additional bonding to
<strong>the</strong> <strong>fibres</strong>. Wet strength resins are used in paperboard to allow it to be used in damp
and wet service conditions. Besides beverage containers, wet-strength resins are used
for packaging fruits, meats and vegetables. These resins make <strong>the</strong> board very difficult to
repulp and are undesirable from an environmental aspect.
Meanwhile, enhancing tensile and tear of <strong>the</strong> board under wet conditions, wet strength
resins provide integrity under moist and wet service conditions existing when cartons
are refrigerated or cooled. To aid repulping, caustic soda is <strong>the</strong> most effective media,
while hypoclorite and o<strong>the</strong>r oxidants can help, mainly when <strong>the</strong> board is totally
bleached. Hypoclorite is however not well seen, for environment, due to <strong>the</strong> presence of
chlorine. Caustic soda causes <strong>the</strong> <strong>fibres</strong> to swell and promote release of ink and wetstrength
added resins.
Researches using o<strong>the</strong>r kinds of chemicals have been done, where peroxyacid showed
to aid pulping tremendously for wet-strength containing boards, while economics being
a relevant factor to be considered on site. Peroxyacid, which is chlorine-free, should
enable a high-consistency pulper to deal with gable top cartons at neutral pH and low
temperature, achieving high yields.
New wet strength resins have been developed that, while providing adequate wet
strength to board, still produces a product that can be mixed into <strong>the</strong> old corrugated
container stream, at a maximum 30%, and allow same repulping of 100% OCC. So far,
<strong>the</strong>re are no reports of <strong>the</strong>se resins being used on boards for Tetra Pak.
Multi-ply boards.
The greatest advantage of a multi-ply board construction is stiffness. Inner plies gives
bulk to <strong>the</strong> board, thus increasing <strong>the</strong> distance and <strong>the</strong>refore <strong>the</strong> contribution of <strong>the</strong> top
and back liners to achieve high stiffness properties. Ano<strong>the</strong>r advantage is <strong>the</strong> possibility
of using lower quality <strong>fibres</strong> on <strong>the</strong> middle layers, once <strong>the</strong>y are not visible from <strong>the</strong>
outside.
Most of <strong>the</strong> boards manufactured for Tetra Pak are multi-plies. Even <strong>the</strong> ones called
“duplex boards” are generally multi-ply, like <strong>the</strong> one manufactured by Klabin, in Brazil.
Klabin makes a triplex board for <strong>the</strong> manufacturing of aseptic packages, where bottom
and middle layers are unbleached softwood pulps and <strong>the</strong> top layer is a mixture of
bleached softwood and hardwood pulps. All bleaching done at <strong>the</strong> Klabin mill is TCF
(total chlorine free). Above <strong>the</strong> top layer, a dual sizing is applied, where alum, starch
and some o<strong>the</strong>r chemistry are applied to improve printability and water resistance.
Klabin also manufacturers a two-ply board which is used for Tetra Rex®, with a mixture
of bleached softwood and hardwood pulps in both plies. Approximately 1,3% of <strong>the</strong>
weight of a triplex Klabin board consist of chemical inputs. Most hardwood <strong>fibres</strong> for
Klabin come from pine, while softwood <strong>fibres</strong> come from eucalyptus trees.
8

Assi-Domän, located in Sweden, manufactures a four-ply board for Tetra Pak’s aseptic
cartons. The bottom layer is made from unbleached hardwood pulp <strong>fibres</strong>, <strong>the</strong> two
middle layers are made from a mixture of unbleached <strong>fibres</strong> and CTMP <strong>fibres</strong> and <strong>the</strong>
top layer only bleached <strong>fibres</strong>. The coating is done over <strong>the</strong> top ply and includes CaCO 3 ,
TiO 2 and latex. All <strong>fibres</strong> are made under chemical process at Assi-Domän, whose forests
are FSC certified, such as Klabin’s, except for CTMP <strong>fibres</strong>, which are purchased from
STORA. Assi-Domän also has a TCF bleaching process. Most <strong>fibres</strong> used by ei<strong>the</strong>r Assi-
Domain or STORA comes from pine, spruce and birch.
Lately, more and more boards are manufactured for Tetra Pak using CTMP <strong>fibres</strong>, and to
understand why, it is important to understand <strong>the</strong> relative contribution of each individual
internal ply on a multi-ply board. If only kraft <strong>fibres</strong> are used in a six-layer board, <strong>the</strong>
relative contribution to <strong>the</strong> final delivered stiffness will be, approximately:
39%
45%
4%
1%
3%
8%
Top Layer
1st Middle Layer
2nd Middle Layer
3rd Middle layer
4th Middle Layer
Back Layer
Figure 4. Contribution on stiffness by layer in a multi-layer board.
As <strong>the</strong> figure shows, <strong>the</strong> contribution of <strong>the</strong> inner layers is approximately 16% for <strong>the</strong>
total stiffness of <strong>the</strong> board. For stiffness, <strong>the</strong> board can be compared to a concrete wall,
<strong>the</strong> thicker it is, <strong>the</strong> stronger. The use of CTMP <strong>fibres</strong> on <strong>the</strong> middle layers of <strong>the</strong> board
allows it to perform better for stiffness, at same time reducing <strong>the</strong> necessity of bulk and
enabling board manufacturers to offer Tetra Pak a finer and lighter board, which
performs as a thicker and heavier one of sulphate only <strong>fibres</strong>.
IV - Waste paper recycling
Pulping
If <strong>the</strong>re is a mill recycling papers, <strong>the</strong>re is a pulper <strong>the</strong>re. Every rule has exceptions and
as exceptions justify <strong>the</strong> rules, one can find very few plants that rely on different
machinery for recycling paper.
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The pulping (also cited as repulping) purposes are:
Produce a pumpable suspension of cellulose <strong>fibres</strong> into water
Release <strong>fibres</strong> from contaminants and inks
Perform a chemical mixing (if chemicals are needed)
Reduce ink particles
The first commercial installation of a pulper was back at late 30’s. Before that, a more
smashing equipment called Hollander beater was used. The Hollander was invented on
<strong>the</strong> 18 th century and allowed <strong>the</strong> setting of <strong>the</strong> recycled paper industry. Pulpers
increased <strong>the</strong> efficiency and have undergone many changes during <strong>the</strong> last decades,
including <strong>the</strong> development of a number of equipment for contamination removal. Black
Clawson patented <strong>the</strong> name Hydrapulper in <strong>the</strong> 50’s, which is world-wide spread
nowadays as a synonym for pulper.
In order to provide more information about pulping systems available in <strong>the</strong> market, it’s
interesting to split systems by <strong>the</strong> consistency at which stock is pulped and also by <strong>the</strong>
working regime.
Consistency:
Low-consistency pulpers run stock up to 6%.
Medium-consistency pulpers run stock from 8 to 11%.
High-consistency pulpers run stock from 12 to 18%.
Operating process:
Batch pulpers, means a load is pulped, <strong>the</strong>n discharged, and <strong>the</strong>n ano<strong>the</strong>r load is
pulped and so on.
Continuous pulpers, means loads are continuously fed into <strong>the</strong> pulper, while stock is
continuously extracted as well.
Consistency, operating process, pulping time, grade of waste paper and energy
consumption are related variables and every paper mill rely on experience to determine
<strong>the</strong> best combination to use
1. Batch pulpers, at low-consistency
Basic process, which pulpers were originally created for. Loads are fed into <strong>the</strong> pulper,
with water, to a certain desired consistency. At <strong>the</strong> bottom of <strong>the</strong> pulper <strong>the</strong>re are a
rotor and a drilled plate.
The pulper is filled with water and a load of paper is dropped into <strong>the</strong> vat, while <strong>the</strong>
rotor is already spinning. The rotor will provide <strong>the</strong> mechanical forces that will turn <strong>the</strong>
stuff into a solution. After a certain period of time, normally 10 to 30 minutes, <strong>the</strong> stock
is extracted through <strong>the</strong> drilled plate, which prevents coarse contaminants such as
plastic sheets to leave <strong>the</strong> pulper with <strong>the</strong> stock.
Very simple process generally associated to small production, low cost system for low
value final product.
2. Batch pulpers, at high-consistency
New kinds of rotor were developed in <strong>the</strong> last 30 years, enabling pulping to be done at
higher consistencies. The main advantage of higher consistencies is <strong>the</strong> great increase
of hydraulic forces inside <strong>the</strong> vat, promoting a gentle pulping action done fibre-to-fibre,
instead of rotor-to-fibre. Fibre strength properties improve as pulping consistencies go
10

higher. Low-consistency rotors cut <strong>the</strong> <strong>fibres</strong> a lot, compromising some of <strong>the</strong>ir
properties, while high-consistency rotors were designed with non-cutting edges. It is
proved that this action among <strong>fibres</strong> is much more powerful to detach ink particles from
<strong>the</strong> <strong>fibres</strong>, which led several deinking plants to choose high consistency pulping. Ano<strong>the</strong>r
obvious advantage is <strong>the</strong> augment of production, once some three times more <strong>fibres</strong> can
be processed comparing to a low-consistency pulper of same size.
It is said <strong>the</strong> high-consistency batch pulping is <strong>the</strong> best for difficult grades of paper,
even wet-strength.
High-consistency batch pulpers may have an extraction plate under <strong>the</strong> rotor or not.
Those who don’t, require an additional piece of machinery, a detrasher, also normally
called Poire (trademark of <strong>the</strong> first one developed, created by Lamort), which pumps out
all stock and retain contaminants.
Figure 5. High-consistency pulping, with a detrasher
Batch pulpers, at medium-consistency
Hybrid rotors were created, trying to ga<strong>the</strong>r <strong>the</strong> advantages of both processes of high
and low consistency, in only one. Of course, disadvantages are ga<strong>the</strong>red as well. The
most important feature is a combination of rotor-to-fibre and fibre-to-fibre actions,
which is especially interesting for wet-strength papers or wax-coated boards. Lowconsistency
pulpers can normally be retrofitted by replacing <strong>the</strong> rotor by a mid-con rotor
(and generally <strong>the</strong> motor as well, for one more powerful) providing an increase of
production, without significant mechanical changes. These pulpers always have drilled
plates under <strong>the</strong> rotor and don’t require a detrasher.
Continuous pulpers, low-consistency
Since pulpers have to be cleaned, every now and <strong>the</strong>n, it was impossible to run pulpers
continuously without <strong>the</strong> invention of detrashers, which work in batch cycles, removing
water, <strong>fibres</strong> and contaminants from <strong>the</strong> pulper and <strong>the</strong>n dumping <strong>the</strong> contaminants
away from <strong>the</strong> system, allowing <strong>the</strong> pulper to keep running. For large productions, drum
washers are installed after <strong>the</strong> detrashers, washing <strong>the</strong> contaminants and recovering as
much <strong>fibres</strong> as possible.
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Continuous pulpers are calculated by <strong>the</strong> assumption of how long it takes for
defibering papers, which is <strong>the</strong>oretically <strong>the</strong> ratio between <strong>the</strong> volume of <strong>the</strong> vat
and <strong>the</strong> flow at <strong>the</strong> accepts chamber.
Figure 6. Continuous pulping
Detrashers (for continuous pulpers):
Detrashers can be compared as small pulpers, which will receive most of <strong>the</strong>
contamination from inside <strong>the</strong> main pulper, accept <strong>the</strong> good stock through its own
perforated plate and <strong>the</strong>n be cleaned. The process is batch and generally automated.
During <strong>the</strong> “extraction” stage, stock is freely flowing from <strong>the</strong> pulper to <strong>the</strong> detrasher
and once accepted through <strong>the</strong> detrasher it flows for fur<strong>the</strong>r processing. During <strong>the</strong>
“washing” stage, stock stops flowing from <strong>the</strong> pulper and water is injected at <strong>the</strong>
detrasher for washing <strong>the</strong> plastics and accepting as much <strong>fibres</strong> as possible. Then <strong>the</strong>re
is <strong>the</strong> “dumping” stage, where <strong>the</strong> contaminants are released form <strong>the</strong> detrasher ei<strong>the</strong>r
to a bin or to a drum washer for a final fibre recovery.
Drum washers:
A perforated rotating cylinder receives <strong>the</strong> rejects from <strong>the</strong> pulper or from <strong>the</strong> detrasher.
Showers help washing those rejects and recovering <strong>fibres</strong>. Rejects are dumped for
fur<strong>the</strong>r processing, while <strong>the</strong> white water is reused.
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Figures 7 and 8. Drum washer (sketch and picture)
Continuous pulpers, high-consistency
Drum pulpers were designed to perform gently as high-consistency rotors do, while
delivering a superior capacity. A rotating drum internally divided in a defiberizing and a
screening section. Both sections have series of baffles and lifters to reduce bales and
loose furnish into a fibre and water slurry. A whole set of showers and pumps help <strong>the</strong>
process and allows <strong>the</strong> final stock and rejects to be discharged.
Bales and loosen papers are fed into <strong>the</strong> defiberizing section, where <strong>the</strong>y are chemically
wet (water and caustic soda). Through <strong>the</strong> combination of baffles, lifters and rotation,
furnish is dropped several times while travelling through <strong>the</strong> section. Effective shearing
forces fiberize papers with minimum degradation of contaminants. From <strong>the</strong> defiberizing
section, <strong>fibres</strong> are transferred to <strong>the</strong> screening section, where <strong>the</strong> consistency is
gradually dropped and stock is accepted through <strong>the</strong> holes (typically 7mm). Rejects are
all materials not accepted at <strong>the</strong> screening section of <strong>the</strong> drum repulper.
Figures 9 and 10. Drum pulper, sketch and working principle
For liquid packaging repulping, a shredder must be installed at <strong>the</strong> inlet section of <strong>the</strong>
drum repulper, o<strong>the</strong>rwise <strong>the</strong> laminated boards will be hardly defiberized, and high
temperatures are higher pH are used. Ano<strong>the</strong>r inconvenience of drum pulpers is its cost,
much higher than <strong>the</strong> o<strong>the</strong>rs kinds of pulper mentioned before.
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After <strong>the</strong> defibering has occurred inside <strong>the</strong> pulper, <strong>the</strong> stream of water and
<strong>fibres</strong> (stock) has to be cleaned, as contamination is expect when you deal with
post-consumer and even post-industrial waste paper. The way to clean <strong>the</strong> stock
is ei<strong>the</strong>r by density (sorting materials which density is different than that of
water (1) and pulp (near 1) or by size.
Screening
Pressurised screens are used to clean stock by removing debris that larger in at least
one dimension than papermaking <strong>fibres</strong>. High quality papers will demand a large
number of screens (series and various stages) with minimum openings. The first
screens in <strong>the</strong> system are called coarse screens and generally have holes (1 to 3mm)
and are followed by o<strong>the</strong>r pressure screens with slots (0.1 to 0.4mm) called fine
screens. Pressure screens are built in a number of sizes and are sized by <strong>the</strong> flow and
quality required.
Stock (water and <strong>fibres</strong>) is pumped into <strong>the</strong> machine and forced to pass through <strong>the</strong>
holes or slots. For this hydraulic system to run, a differential pressure is always kept
between inlet/outlet, to avoid <strong>fibres</strong> to form a mat over <strong>the</strong> screen and consequently
blind <strong>the</strong> openings of <strong>the</strong> drilled/slotted screen. Some stock is continuously rejected,
carrying most of <strong>the</strong> contaminants.
In order to recover <strong>fibres</strong>,
secondary, tertiary and even
quaternary stages are used,
screening <strong>the</strong> residuals of each
previous stage. Generally all
stages use same type of screen
and <strong>the</strong>ir accepts can be redirect
to <strong>the</strong> system or to <strong>the</strong> stage
before.
Normal types of debris
screenable are plastics,
undefibered paper flakes like
wet-strength papers and
adhesives. Pressurised screens
can be horizontal or vertical.
Cylindrical screens are always
used, and a rotor cleans <strong>the</strong>
openings and maintains <strong>the</strong> flow.
Figure 11. An Ultra-V Pressure Screen
14

Pressure screens are also
used for fractionation,
which means <strong>the</strong>
separation of long and
short <strong>fibres</strong>. This is very
interesting when a multilayer
paper is
manufactured and different
quality is required for each
layer. Linerboard, for
instance, will benefit of <strong>the</strong>
use of long <strong>fibres</strong> at <strong>the</strong> top
ply. Therefore, a screen
can be set for a higher rate
of rejection than normal
(up to 50%) which will
enable more of <strong>the</strong> long
<strong>fibres</strong> to be rejected, while
short <strong>fibres</strong> will most likely
pass through he openings
of <strong>the</strong> screen.
Figure 12. Comparison among
screen holes and slots and
contaminants size
Centrifugal cleaning
Contaminants such as dust and sand can not be sorted by size. Density is used for <strong>the</strong>
separation of very small particles, which density is not near 1. Usually centrifugal
cleaners are called only cleaners and <strong>the</strong>y can be high-density (HD) cleaners; medium
density (MD) cleaners; forward cleaners and reverse cleaners. The working principle is
basically <strong>the</strong> same for all of <strong>the</strong>m.
Stock is fed tangentially close to <strong>the</strong> top of <strong>the</strong> cleaner body. Stock <strong>the</strong>n rotates within
<strong>the</strong> cleaner body. The vortex created, as speeds are higher while <strong>the</strong> diameter of <strong>the</strong>
cleaner is diminishing, make heavier particles concentrate at <strong>the</strong> centre of <strong>the</strong> vortex. As
<strong>the</strong> volume is restricted, <strong>the</strong> inner area of <strong>the</strong> vortex is forced to move ei<strong>the</strong>r up or
down, and is conducted out of <strong>the</strong> cleaner body, thus separating <strong>the</strong> heaviest particles
in suspension.
HD cleaners are low-efficient cleaners, but deal with large volumes and high
consistency, so <strong>the</strong>y are used just after <strong>the</strong> pulper and will remove metals, glass,
grit and o<strong>the</strong>r heavy stuff, than can damage <strong>the</strong> pressure screens.
15

MD cleaners are sometimes used as an additional protection to <strong>the</strong> slots of fine screens
<strong>the</strong>refore installed between coarse and fine screens.
Forward cleaners are generally installed in banks and most are manufactured in PVC.
They will sort particles over 1.0 in density, and are very good for sand removal.
Reverse cleaners perform as
<strong>the</strong> o<strong>the</strong>r cleaners, but here
<strong>the</strong> idea is to separate <strong>the</strong>
particles on <strong>the</strong> outside area
of <strong>the</strong> vortex, which are
lighter, from <strong>the</strong> stream.
Reverse cleaners were
developed for <strong>the</strong> removal
of wax, paraffin, glues and
o<strong>the</strong>r light contamination.
Figure 13. A bank of X-Clones
Normal types of contaminants are:
Type of contaminant Density (kg/dm3) Particle sizes (µm)
Clay 1.8 – 2.6 < 40
Hot melts 0.95 – 1.1 40 to 4000
Ink 1.2 – 1.6 < 400
Latex 0.9 – 1.1 40 to 4000
Metal 6.0 – 9.0 > 4000
Polyethylene 0.9 – 0.97 > 400
Polystyrene 1.04 – 1.1 > 400
Styrofoam 0.3 – 0.5 > 400
Wax 0.9 – 1.0 < 40
Every solid particle inside a cleaner is subjected to four different forces:
Centrifugal, always directed away from <strong>the</strong> centre of <strong>the</strong> cleaner;
Buoyancy, due to pressure gradient, as a result of <strong>the</strong> displacement of <strong>the</strong> equal
volume of fluid;
Drag, toward <strong>the</strong> centre of <strong>the</strong> cleaner, as most of <strong>the</strong> fluid is flowing from <strong>the</strong> outer
vortex to <strong>the</strong> inner vortex;
Lift, as particles are also spinning and tumbling about its own centre of gravity.
Refining
Refiners are used to reduce <strong>the</strong> freeness of <strong>the</strong> stock. In o<strong>the</strong>r words, change drainage
characteristics. Also, refining will affect sheet strength, bulk, porosity, smoothness and
16

printing characteristics. Refining is energy consuming and is often done just as
necessary to permit a good final bonding of <strong>fibres</strong> for <strong>the</strong> paper that will be
manufactured. Refining does not clean <strong>the</strong> stock, although sometimes it reduces <strong>the</strong> size
of <strong>the</strong> contaminants, breaking <strong>the</strong>m to pieces.
Compared to virgin <strong>fibres</strong>, recycled <strong>fibres</strong> generally present: lower freeness, reduced
fibre length, increased amount of fines, lower strength properties, increased opacity,
inferior bonding, less swelling and flexibility, lower water retention and reduced
fibrillation. Disk or conical plates are used, presenting a wide range of dimensions, to
perform mechanical attrition. Intensity and choice of treatment is designed according to
<strong>the</strong> <strong>fibres</strong> to be processed, <strong>the</strong> final product to be made and to <strong>the</strong> kind of refiner used
Washing, Deinking and Dispersion
Washers are pieces of equipment that remove dispersed ink, fines and starch from <strong>the</strong>
stock. They are mainly used in tissue mills, where softness is a desirable feature of <strong>the</strong>
paper, by removing fillers. It is a typical rinsing process, performed at a wide range of
consistencies and operating conditions.
Deinkers are used for ink removal. The most
common types of deinkers are flotation cells
that use air bubbles dispersed in <strong>the</strong> stock at
low-consistency. Air bubbles are injected at
<strong>the</strong> bottom of <strong>the</strong> equipment, whereas stock
comes from <strong>the</strong> top. On <strong>the</strong>ir way to <strong>the</strong>
surface, <strong>the</strong> bubbles tend to grab ink
particles, which area is bigger than <strong>the</strong> area
occupied by <strong>fibres</strong>. Both washing and
deinking stages will increase <strong>the</strong> brightness of
<strong>the</strong> final papers.
Figure 14. A MacCell Flotation cell (operating principle)
Dispergers are designed to shred small particles of ink and o<strong>the</strong>r contaminants into
pieces. The goal here is to reduce <strong>the</strong> amount of visible particles of contamination, but
not to effectively remove <strong>the</strong>m from <strong>the</strong> stock.
Systems
A system designed for waste paper treatment is a combination of equipment listed
above, and is generally tailor-made, or designed according to specific requirements of
each paper mill, to product, performance, cost and manufacturer’s experience.
17

A typical high-class tissue system could be:
High
Consistency
Pulper
Poire
High
Density
Cleaners
Coarse
Pressure
Screen (2
stages)
Drum
Washer
Secondary
Fine Screen
(2 stages)
Primary
Forward
Cleaners (4
stages)
Primary
Flotation
Primary
Fine
Screens (2
stages)
Reverse
Cleaners (2
stages)
Thickener Dispersion Primary
Bleaching
Secondary
Bleaching
Washing
Secondary
Forward
Cleaners (3
stages)
Secondary
Flotation
Tertiary
Bleaching
Refining
This sketch looks complex, but still doesn’t show rejects handling, <strong>the</strong> water
system, chemistry system, pumps, steam and so on. The most complex <strong>the</strong>
waste paper treatment is, <strong>the</strong> highest its capacity to turn cheapest <strong>fibres</strong> into
high value paper products.
18

V - <strong>Recycling</strong> cartons
TBA, TFA, TWA, TPA
Aseptic cartons are easily repulpable in water. They can be recycled virtually by any kind
of pulping process previously described in this document. And <strong>the</strong>y pulp fast, due to <strong>the</strong>
quality and properties of <strong>the</strong> <strong>fibres</strong> used. Defibering <strong>the</strong> cartons is not a problem, and
<strong>the</strong> process happens as water penetrates inside <strong>the</strong> polyethylene layers and is absorbed
by <strong>the</strong> <strong>fibres</strong>. It may require few additional minutes in batch processes, however, but
defibering is so easy pulping times are very conventional and well below general
expectations.
As an exception, continuos pulping at low-consistency should be avoided whenever
possible. Low residence time for <strong>fibres</strong> inside <strong>the</strong> pulper and <strong>the</strong> difficulty to handle
residuals are <strong>the</strong> main reasons. Also, as polyethylene is lighter than water, <strong>the</strong>re is a big
trend to float, jeopardising <strong>the</strong> process after a while. If low-consistency continuous is
<strong>the</strong> only process available, special attention has to be given to running <strong>the</strong> pulper at a
low level, to increase <strong>the</strong> agitation capacity. Also, detrashing cycle time (if available)
shall be adjusted. Alternatively, blending aseptic cartons with o<strong>the</strong>r secondary <strong>fibres</strong>,
such as OCC, should enable low-consistency continuous pulping, as reported in a trial in
Australia done at Amcor Botany Mill, that concluded: “The trial shows that aseptic
cartons … could be repulped in a continuous operation toge<strong>the</strong>r with mixed paper
grades at levels up to 5%”.
Despite <strong>the</strong> general perception that aseptic cartons are hard to pulp, <strong>the</strong> real problem is
<strong>the</strong> amount of non-wood materials in <strong>the</strong> carton. <strong>Recycling</strong> paper mills are generally not
prepared to deal with more than 5% of contamination of solids on post-consumer
papers inside <strong>the</strong> pulper, but aseptic cartons can deliver from 25% (TBA 1000ml base)
to some 50% (TFA 500ml). For batch processes, all those residuals have to be taken
away from <strong>the</strong> vat of <strong>the</strong> pulper, before a new batch commences. For continuous highconsistency
processes, <strong>the</strong> residuals will be continuously dumped, while continuous lowconsistency
processes will require that a detrashing system is in place (usually is) and
reset for new timing intervals for purging <strong>the</strong> unit.
The most effective manner to clean batch pulpers is to use a drum washer, directly
piped to <strong>the</strong> pulper vat. Residuals inside <strong>the</strong> pulper can be flushed away into <strong>the</strong> drum
screen, where showers will help washing remaining <strong>fibres</strong> away from <strong>the</strong> contaminants
and <strong>the</strong>refore allowing those <strong>fibres</strong> and water to be reused in <strong>the</strong> following batch.
As any o<strong>the</strong>r source of <strong>fibres</strong>, heated water will make pulping easier, but is not
mandatory. Important, no chemicals are needed for <strong>the</strong> pulping of aseptic cartons,
despite <strong>the</strong> general perception. Bringing a new source of <strong>fibres</strong> to a paper mill may
require some attention to <strong>the</strong> chemical products already in use at <strong>the</strong> mill. Fibre
flocculants for instance are sometimes used for improving sheet formation, however
<strong>the</strong>y tend to agglomerate <strong>the</strong> bleached <strong>fibres</strong> from multi-ply boards and show white
spots on paper.
19

Paper products manufactured from recovered aseptic cartons can be of a very good
quality. Around <strong>the</strong> pulper is usually <strong>the</strong> place to spend time in a paper mill until figured
out how to achieve <strong>the</strong> best performance from <strong>the</strong> system. Attention also has to be paid
for <strong>the</strong> screening to avoid contamination of <strong>the</strong> final product from pieces of aluminium
and plastic.
Yield may be a concern to a certain extent. Of course <strong>the</strong> paper mill will not benefit from
<strong>the</strong> plastic and aluminium and so yield can’t be higher than 75%, as mentioned above,
considering all <strong>fibres</strong> are recovered and <strong>the</strong> rejects are very clean. It is very obvious and
intuitive to say that a newspaper or a magazine will deliver a better yield, as seems to
be no unrecoverable material <strong>the</strong>re. What yield does a paper mill achieve using o<strong>the</strong>r
materials?
Numbers below are <strong>the</strong> ones guaranteed by equipment suppliers, for new state-of-<strong>the</strong>art
stock preparation systems, designed to remove maximum contamination while
loosing as few <strong>fibres</strong> as possible. Cheaper systems powered with less technology (<strong>the</strong>
majority in <strong>the</strong> market) will ei<strong>the</strong>r deliver more contamination on <strong>the</strong> paper with
approximate yield or, most probably, reduce yield by dumping <strong>fibres</strong> with contaminants
to reach quality standards.
Product Raw Material Yield (%)
Newsprint Old Newsprint-ONP (60%) and Old Magazines-OMG (40%) 85-88%
Topliner White Ledger (100%) 74-76%
Fine Paper Mixed Office Waste – MOW (100%) 68-72%
Tissue White Ledger (80%) and Old Magazines-OMG (20%) 62-66%
Cardboard Old Corrugated Containers – OCC (%) 93-95%
Due to chemistry, unrecoverable <strong>fibres</strong> etc. yields from waste paper are not as high as
perception could suggest and all those unrecovered materials will have to be handled by
<strong>the</strong> water treatment system of <strong>the</strong> paper mill. Replacing o<strong>the</strong>r raw materials with aseptic
cartons a paper mill may be able to maintain its normal production yield while refreshing
<strong>the</strong> water treatment system operation.
TR
The bleached <strong>fibres</strong> used for Tetra Rex ® cartons are a very good raw material for tissue
mills and for o<strong>the</strong>r high quality white grades of paper.
TR cartons by <strong>the</strong>mselves are generally suitable for all pulping processes, like aseptic
cartons. Although not having aluminium (except for some HAAD Tetra Rex packages)
<strong>the</strong> plastic layers can be easily peeled from <strong>the</strong> board inside <strong>the</strong> pulper.
The chemistry varies depending on <strong>the</strong> board manufacturer and some wet-streng<strong>the</strong>ning
chemistry may be used, enforcing <strong>the</strong> use of chemistry for pulping. If so, medium and
high consistency pulping is generally desirable, at hot temperature (for faster fibre
impregnation with water) and under a high pH (9 to 12). Temperature can be achieved
by <strong>the</strong> use of steam and recommendation is around 60 o C. The pH is increased with
caustics. O<strong>the</strong>r chemical products can be used to specifically break <strong>the</strong> wet strength of
20

<strong>the</strong> cartons and when used can reduce pulping time (generally 20 to 40 minutes) and
improve yield.
Gable top packages manufactured by o<strong>the</strong>r companies (IP, for instance) are usually
harder to pulp and not fall under <strong>the</strong> specifications above.
TB, TT
Without aluminium and with a minimum of wet-strength chemistry added to <strong>the</strong> <strong>fibres</strong>,
<strong>the</strong>se cartons are quite easy to pulp and when mixed with o<strong>the</strong>r grades of waste paper
are hardly noticed by a paper mill.
If recovered as a separate stream, <strong>the</strong> great amount of plastic present on Tetra Top ®
packages will require same attention as aseptic cartons for <strong>the</strong> pulping residuals
Mixed cartons
Most of <strong>the</strong> times, cartons don’t come separate for pulping. All information above was
concerning separate streams and is valid to understand what happens when cartons are
mixed. But <strong>the</strong> way cartons are recovered for recycling depend on market share,
collection system and so on.
Cartons can also be mixed among <strong>the</strong>mselves or with o<strong>the</strong>r grades of waste paper
(secondary fibre). Of course, cartons manufactured by <strong>the</strong> competitors of Tetra Pak are
also possibly in <strong>the</strong>se mixtures. We know that aseptic cartons manufactured by
Combibloc behave approximately like <strong>the</strong> ones made by Tetra Pak. Gable tops from
International Paper, however are way tougher to repulp than TR. The gable top
packages require temperatures over 65 o C, pH of 11-12 and pulping time at highconsistency
is 40 to 60 minutes.
Blends of aseptic cartons and gable tops are probably <strong>the</strong> most usually found mixtures
of beverage cartons available. Pulping TR, Aseptic cartons and Gable Tops toge<strong>the</strong>r is
not desirable, once pulping conditions are not <strong>the</strong> same. Therefore <strong>the</strong>re are basically
three conditions:
Mixtures where aseptic cartons are dominant, with small amounts of <strong>the</strong> o<strong>the</strong>rs (TR
is much more tolerated than GT). In this case, pulping conditions for aseptic cartons
should be used, and most of GT will not pulp, becoming part of <strong>the</strong> residuals and
reducing yield. This also normally jeopardises <strong>the</strong> reuse of <strong>the</strong> pulping residuals
(polyethylene and aluminium) as <strong>the</strong> GTs will be mixed toge<strong>the</strong>r with <strong>the</strong>m.
Mixtures where GT and TR are dominant, so aseptic cartons become contaminants.
Due to <strong>the</strong> high pH conditions, <strong>the</strong> aluminium foils will oxide and granulate,
becoming a major problem as paper contamination. Also, <strong>the</strong> long time required for
pulping will increase <strong>the</strong> shredding of <strong>the</strong> aluminium/poly sandwich, leading to
increasing levels of contamination. Some recyclers in <strong>the</strong> USA do not tolerate over
5% of aseptic cartons when pulping GT.
21

Mixtures where beverage cartons are blended with o<strong>the</strong>r grades of paper, generally
in amounts below 50%. Pulping conditions will be determined by a handful of
factors, including paper to be made, grades of o<strong>the</strong>r <strong>fibres</strong> pulped, type of pulping
process etc. This is probably <strong>the</strong> most common application, as <strong>the</strong> collection of
beverage cartons is usually smaller than <strong>the</strong> consumption of a paper mill. It is also a
good way to start supplying <strong>fibres</strong> to a paper mill, so <strong>the</strong>y become familiar with <strong>the</strong>
quality of <strong>the</strong> <strong>fibres</strong>.
Trials recently done by Voith show how blends of cartons behave as a function of
pulping time. The 1st chart, comparing separate streams at same temperature, shows
no significant improvement on <strong>the</strong> defibering of GT cartons, even after 80 min of
pulping. Tetra Rex® cartons, however, achieves same degree of repulping that aseptic
cartons, but after a six times longer period. Experiences at Atlantic Packaging in Canada
with Gable Top cartons, in a medium consistency batch pulper at room temperature and
neutral pH showed that defibering was not achieved even after 3 hours of pulping.
Fibre Flakes versus Pulping Time
Full Scale Trial
fibre flakes (Somerville // 0.15 mm) [%]
70
60
50
40
30
20
10
0
Customer trial:
Trial no.:
Series 1 (100 % TBA)
Series 5 (100 % GT)
Series 25 (100 % Tetra Rex)
0 10 20 30 40 50 60 70 80 90
Lund 3
08712
Pulping Time [min]
Ano<strong>the</strong>r chart from those trials compare blends of aseptic cartons and gable top cartons,
with separate streams as wells. It is notable how a long tome residence inside <strong>the</strong>
pulper compromises <strong>the</strong> pulping of aseptic cartons.
22

Fibre Flakes versus Pulping Time
Full Scale Trial
fibre flakes (Somerville // 0.15 mm) [%]
70
60
50
40
30
20
10
0
Series 1 (100 % TBA)
Series 5 (100 % GT)
Series 6 (50 % GT, 50 % TBA - 80 °C)
Series 10 (50 % GT, 50 % TBA - 40 °C)
Series 16 (75 % TBA + 25 % GT)
0 10 20 30 40 50 60 70 80 90
Customer trial:
Trial no.:
Lund 3
08712
Pulping Time [min]
VI - Existing systems (selection)
This is a selection of paper mills currently running cartons manufactured by Tetra Pak.
Upgrades to this paper shall be done and reports from o<strong>the</strong>r mills are also welcome.
Atlantic Packaging, Scarborough, ON, Canada
This centennial mill was <strong>the</strong> first one in Canada to produce only 100% recycled papers.
Their tissue operation starts with two 14’ BC mid-con pulpers of same size installed side
by side, each one capable of respond to <strong>the</strong> total capacity of <strong>the</strong> inclined wire paper
machine. In <strong>the</strong> year 2000, Atlantic added a Selectpurge 5000 drum washer to one of
<strong>the</strong>ir mid-con pulpers, thus
enabling <strong>the</strong> recycling of
aseptic cartons. The
Selectpurge selected for <strong>the</strong>
operation has 3/8” holes and
for additional washing control,
a variable speed motor was
installed, to allow adjustments
to <strong>the</strong> timing of <strong>the</strong> washing
cycle.
Figure 15: Mid-con pulper
23

As <strong>the</strong>re are twin pulpers in this mill, <strong>the</strong> Selectpurge was installed in one of <strong>the</strong>m, so
Atlantic runs “clean raw materials” that means few residuals inside <strong>the</strong> pulper, on pulper
#1 and aseptic cartons or o<strong>the</strong>r materials with high amounts of residuals on pulper #2.
Being clean material doesn’t necessarily mean a high yield, as it is normal for mixed
office waste to yield only 60%, due to high amounts of starch and fines.
Rejects from <strong>the</strong> Selectpurge are conveyered to a baler, that presses and form bales, to
allow long distance travelling. Results from <strong>the</strong> first bales showed less than 2%
remaining humidity and also very few <strong>fibres</strong>, although not measured. The baler is
horizontal, with automatic tying system, loading 210 bar with a 178mm cylinder.
Figure 16: Rejects from drum washer
Figure 17: Bales of Poly and Al
Currently, <strong>fibres</strong> extracted from aseptic cartons are been mixed with OMG, ledger and
graphic clippings to manufacture paper towels. The mill can run up to 100% using
aseptic cartons, and paper from 100% aseptic cartons was once done, as shown below,
but is not a reality as <strong>the</strong> volumes recovered from post-consumer collections are far
below <strong>the</strong>ir capacity. Atlantic could handle all aseptic cartons sold by Tetra Pak in
Canada in 1999.
After pulped, <strong>fibres</strong> are high-density cleaned and coarse screened with Finch 1.8 mm
coarse screens (one loop for each pulper), when <strong>the</strong>y are blended in a storage chest, for
fur<strong>the</strong>r fine screening (as low as 0.10mm), forward cleaning, washing, deinking,
bleaching and refining.
24

Figure 18: Prototype paper roll made only from TBA cartons at Atlantic Packaging
Crown Packaging, Burnaby, BC, Canada
Greencoast is <strong>the</strong> name of <strong>the</strong> plant Crown Packaging has in Burnaby. They are
dedicated to making paper from recycled <strong>fibres</strong>. Their main product at that plant is
gypsum, sold to gypsum board manufacturers.
They decided to recycle beverage containers using a BC 14’ft mid-con pulper, same as
Atlantic Packaging. Greencoast added a Selectpurge 5000 to <strong>the</strong> system, with holes of
6.2mm. All water from <strong>the</strong> Selectpurge is used to fill <strong>the</strong> pulper for <strong>the</strong> following load.
Figure 19: Rejects from drum washer, after pulping
Greencoast started recycling aseptic cartons as of October 2000, and will add gable tops
six months later. For <strong>the</strong> gable tops, <strong>the</strong>y will be using water from a hot water tank, pre
25

mixed with caustics, which will be delivering water at pH 11 to 12 and water from 60 to
75 o C.
In order to have as few <strong>fibres</strong> mixed with <strong>the</strong> rejects as possible, several trials were
performed in order to find <strong>the</strong> best way to handle <strong>the</strong> dump of <strong>the</strong> pulper. The current
cycle used is to extract <strong>the</strong> <strong>fibres</strong> through
<strong>the</strong> extraction plate for as long as possible.
More water is <strong>the</strong>n added and when <strong>the</strong>
level in <strong>the</strong> pulper is approaching 1/3, <strong>the</strong>
dump valve is opened to some 20% and
<strong>the</strong>n slowly ramped up to 50%, while <strong>the</strong>
water extracted by <strong>the</strong> drum washer is
being fed again in <strong>the</strong> pulper. The whole
process takes approximately 4 minutes and
has delivered so far very “clean” rejects.
Figure 20: Aspect of <strong>the</strong> rejects from drum washer
From <strong>the</strong> pulper, <strong>fibres</strong> (ei<strong>the</strong>r from aseptic cartons or gable tops) will pass through HD
cleaners, 1.4mm Ultra-V coarse screens, medium consistency cleaners (3, in parallel),
Ultra-V fine screens with 0.25mm slots, 2 stages of BC X-Clones (60-3-cbt and 6-3-bt)
reverse cleaners and 3 stages Bird forward cleaners (22, 8 & 3), before refining,
dispersion and approach-flow final cleaning.
Fiskeby, Sweden
This Swedish company recycles a mixed waste stream, that includes aseptic and gable
top cartons using a large high consistency continuous drum pulper, from Ahlstrom. From
<strong>the</strong> drum pulper, centrifugal cleaners and pressurised screens clean <strong>the</strong> <strong>fibres</strong>. Rejects
from <strong>the</strong> pulper are a blend of different contaminant materials and are landfilled.
Fiskeby has ano<strong>the</strong>r line with a high-consistency pulper, which <strong>the</strong>y use for gable top
cartons.
The main products manufactured by Fiskeby are packaging boards for food boxes
Figure 21: High consistency rotor at Fiskeby
26

Klabin Fabricadora de Papel e Celulose, Piracicaba, SP, Brazil
This mill started-up a new linerboard system for boxboard production, early in 1999.
Their brand new system was designed to handle and blend two separate processing
lines, 250 metric tons per day of OCC and 50 metric tons per day of Tetra Pak aseptic
cartons, from ei<strong>the</strong>r post-consumer or post-industrial source. The OCC line has
continuous pulping, fractionation and several screening and cleaning steps.
Figures 22 and 23: Pulping aseptic cartons on a high-consistency pulper
The line that is dedicated for recycling Tetra Pak cartons is comprised of <strong>the</strong> following
steps:
High-consistency pulping: batch pulping on a 12-foot diameter Hi-Con Pulper, no
chemicals are added and pulping time is around 21 minutes. Total batch time is slightly
over 32 minutes. Capacity for this pulper is almost 100 tons a day. The pulper has
drilled plate underneath <strong>the</strong> rotor, with 9.5 mm holes, for fibre/water extraction. There
is no automated consistency control, but 12% to 15% is <strong>the</strong> desired range of operation.
Drum washer: A Selectpurge 4500
was installed beside <strong>the</strong> pulper,
where <strong>the</strong> residuals are dumped at
<strong>the</strong> end of each batch. The drum
screen has <strong>the</strong> same size of holes as
<strong>the</strong> pulper (9.5 mm) and <strong>the</strong> washing
water is reused for filling up <strong>the</strong>
pulper every new batch.
Figure 24: Drum washer
HD Cleaner: A Liquid Cyclone #10 with automated reject dumping is used for <strong>the</strong>
removal of heavy contaminants that eventually will come from <strong>the</strong> waste stream. Typical
contaminants are sand and plastic pieces like PET bottle’s closures.
27

Coarse Screen: Two pressurised Mini-Screens model 50 running in parallel are used at
this cleaning step. Holes of 1.6 mm were chosen for <strong>the</strong> perforated screens and <strong>the</strong>
rejects are sorted on an open
vibratory screen, to ensure
maximum fibre recovery.
Fine Screen: A pressurised model
50 Mini-Screen with slots of 0.2 mm
was chosen to remove small pieces
of plastic (and / or aluminium) that
shall be shredded inside <strong>the</strong> pulper.
Rejects are also sorted in an open
vibratory screen.
Figure 25: Pressurised Screens
Forward cleaners: Centrifugal cleaners
were added to remove particles more
dense than water, such as small flakes
of aluminium, which were too small to
be screened. Three stages of 3-inches
Ultra Clones were used, <strong>the</strong> last one
being equipped with tips for maximum
fibre saving. A total of 46 individual
cleaners are installed, being 34 active.
Figure 26: Forward Cleaners – 3 stages – 3
inches bottles
From <strong>the</strong> cleaners, accepted stock is thickened up to 4.5% in a 60x48 Free-Flow and
sent to refiners. Refining is done accordingly to <strong>the</strong> final product and Klabin’s proper
expertise. The <strong>fibres</strong> from <strong>the</strong> system are mainly used on <strong>the</strong> top ply of <strong>the</strong> linerboard,
due to its quality and cleanliness.
Measurements done by Klabin indicated that only 0.5% of <strong>fibres</strong> were lost with <strong>the</strong>
residual plastic and aluminium (500 grams of <strong>fibres</strong> per 1000 kg of residuals). The mill
state-of-<strong>the</strong>-art water treatment plant ensures this plant totally recycles all waters used
in <strong>the</strong> process, generating no water effluent.
Currently, Klabin sells a product called Ekoliner Out, grade 5 or 10, which is
manufactured with recovered <strong>fibres</strong> from Tetra Pak cartons, containing a minimum of
ei<strong>the</strong>r 5% or 10% of <strong>the</strong>se <strong>fibres</strong>.
28

Figure 27: Kraftliner jumbo roll –
approx. weight 4000 kg
System flow diagram:
CARTONS
PULPER
COARSE
SCREEN
FINE
SCREEN
Fiber + water
HD CLEANER
Polyethylene + aluminium + water
FORWARD
CLEANER
PAPER
PRODUCTION
DRUM WASHER
PLASTIC
PROCESSING
29

Klabin is also a supplier of board for Tetra Pak, <strong>the</strong> only one in South America. They
supply duplex boards for aseptic cartons and also bleached boards for Tetra Rex®
cartons. Klabin is and one of <strong>the</strong> very few American pulp and paper industries to have
<strong>the</strong>ir forests certified by <strong>the</strong> FSC (Forest Stewardship Council).
Orebro Kartongbruk, Sweden
Orebro Kartongbruk belongs to <strong>the</strong> Gypsum Division of Lafarge Platres, a major player in
<strong>the</strong> Gypsum board business world-wide. Orebro Kartongbruk supplies 100% of <strong>the</strong>ir
production to Lafarge for gypsum manufacturing.
The plant has a capacity of 45000 pbl (plasterboard liner), consuming 60000 tons of
recycled <strong>fibres</strong> per year. They have a multi-cylinder machine and <strong>the</strong> board is made
from 100% mixed waste papers, including some average 20 to 25% of post-consumer
beverage cartons,
from Sweden and
Germany. OK has
a high consistency
pulper running at
18% consistency,
operated at 45
degrees Celsius.
No chemicals
added. Pulping
time is 18 to 20
minutes.
Figure 28: hanged high consistency rotor pulping mixed waste
Orebro has a Valmet trommel, near <strong>the</strong> pulper, where <strong>the</strong>y dump <strong>the</strong> pulper load when
20% of <strong>the</strong> volume of
<strong>the</strong> pulper is reached.
Trommel has 8mm
holes while <strong>the</strong>
extraction plate inside
<strong>the</strong> pulper has 15mm.
After pulping <strong>the</strong>y
have conventional
cleaning systems,
including 0.25mm fine
screens and also
fractionation with
0.15mm screens.
Figure 29: Valmet drum washer and Celli high consistency pulper
30

For <strong>the</strong> white top layer, OK uses mainly beverage cartons (post-industrial scraps from
competitors), mostly gable top, bleached wet-strength sulphate pulp, that is pulped at
high-consistency as well, under hot temperature and high pH (caustics added).
Residuals from <strong>the</strong> pulping operation are processed in a fluid bed boiler for energy
recoverage, energy that ultimately is used at <strong>the</strong> paper mill production.
Papeles Nacionales, Pereira, Colombia
(From a report by Fernando Neves)
Papeles Nacionales is a paper mill located about 200 Km from Bogotá. This factory
produces recycled tissue paper using 50% Old corrugated containers (OCC), 25%
Catalog Paper (CP) and 25% Old Newsprint (ONP). Their total production is 175
ton/day. Pulping is done in a High consistency pulper (~ 15%) with Helico rotor,
manufactured by Lamort. The <strong>fibres</strong> and rejects pass through a poire (detrasher) after
repulping. The pulp goes direct to <strong>the</strong> pulp tank and <strong>the</strong>n <strong>the</strong> waste (polyethylene and
aluminium) is collected in a container, located under <strong>the</strong> poire.
Figure 30: Poire installation
Figure 31: Rejects from pulping
No problem was detected in <strong>the</strong> paper production or in <strong>the</strong> paper properties. The paper
quality was considered very good and <strong>the</strong> visual aspects were good as well. The photo
below shows that polyethylene and aluminium (toge<strong>the</strong>r with o<strong>the</strong>r contaminants from
waste paper) were discharged quite clean (few <strong>fibres</strong>).
There is ano<strong>the</strong>r pulper that can be used to repulp TBA at 100%. This equipment is a
low consistency pulper with lateral discharge and perforated plate. It is feasible to install
a drum washer.
Papeles Nacionales can use up to 7% of aseptic cartons in <strong>the</strong> pulper, but in order to
have a safety operation it was agreed to work with only 5%.
Papeles Nacionales can consume 150 ton per month that represents 27 % of <strong>the</strong> Tetra
Pak Colombia total production.
31

Scott-Feldmuhle GmbH, Germany
This tissue plant has a 3.25 diameter drum repulper, extended length, that reportedly
runs 180 admtpd of office waste and liquid packaging boards. Office waste is 50 to 60%
of <strong>the</strong> blend, <strong>the</strong> balance being liquid packaging boards. Pulping time is 30 minutes in
average, pH up to 10, temperatures from 40 to 60 degrees Celsius. Fur<strong>the</strong>r steps of <strong>the</strong>
stock preparation include high-density cleaning, coarse screening, forward cleaning, fine
screening, dispersion, flotation and washing. Reported liquid packaging boards include
aseptic cartons and those multi-layered featuring CTMP.
Unit Mixed Waste Office Papers Liquid Packaging
Pulping Time min 20 25 40
Freeness ml 160 390 425
Fines ( 220 µm PPM 2084 4550 1440
Dirt 20-220 µm PPM 18070 9784 695
Yield % 99.5 99.7 68.9
Reject consistency % 24.9 24.5 22
Table 1: Laboratory results for drum repulpers, from European household mixed waste, office papers and
mixed liquid packaging containing sulphate and CTMP <strong>fibres</strong>. (Ahsltrom Kamyr)
Trials on paper mills in Turkey
(From a report by Fernando von Zuben)
Ankara Paper Mill has an old paper machine producing 42 g/m 2 dyed red fruit wrapping
paper. Their production is 20 ton per day mainly from Mixed Office Waste (MOW), using
a low consistency 10 m 3 batch pulper. Fibres are extracted through a perforated plate
underneath <strong>the</strong> rotor. Rejects are separated by using a trap device in <strong>the</strong> top of <strong>the</strong>
pulper as shown below.
Figure 32: Cleaning <strong>the</strong> pulper
32

The normal repulping time for MOW is around 60 minutes and for TBA only 20 minutes.
It means saving time and energy while improving quality by replacing some MOW (short
fibre) for TBA (long fibre). Pulp quality has shown no contamination of plastic or
aluminium meaning <strong>the</strong> cleaning process, without any modification, worked quite well.
Selkasan Paper Mill is located 50 km far from Tetra Pak converting plant in Izmir and is
capable to produce 180 ton per day of corrugated medium using OCC as raw material.
They have one continuous pulper and two high consistency pulpers from Lamort. One of
<strong>the</strong>n (12 m 3 ) is not in use and can be easily adapted to recycle TBA material. The
repulping time for OCC is 20 minutes and <strong>the</strong> total cycle time around 40 minutes.
Dentas Paper Mill is located in Denizil and make 100 tons per day of Kraft liner and
medium paper based on OCC and also produce corrugated boxes on <strong>the</strong> same site. They
have two Voith continuous pulpers and one medium consistency pulper of 22 m 3 . With a
drum washer <strong>the</strong>y could use up to 50 tons per day of TBA as a raw material.
VII - Bibliography
1. Abreu, M. <strong>Recycling</strong> of Tetra Pak Aseptic Cartons. Tetra Pak Canada Inc., Markham,
2000.
2. Darlington, W. B., Lanier, W. G., Gonstad, J.A., McMillen, T.L. Development of a
Repulpable Wet Strength Board. <strong>Recycling</strong> Symposium. TAPPI Press, Atlanta. 1996.
Pg. 91.
3. Ford, Philip A. Recycled Fibre – Its Use And Effect In Fine Papermaking. <strong>Recycling</strong>
Symposium. TAPPI Press, Atlanta. 1995. Pg. 355.
4. Houston, J., Babb, C., Homans, J. Pulping Wet-strength Milk Cartons. <strong>Recycling</strong>
Symposium. TAPPI Press, Atlanta, 1995. Pg. 403.
5. Koffinke, Dick. Drum Repulping System For Liquid Packaging. <strong>Recycling</strong> Symposium.
TAPPI Press, Atlanta. 1996. Pg. 375.
6. Law, K., Valade, J., Quan, J. Effects of recycling on papermaking properties of
mechanical and high yield pulps: pt. I: Hardwood pulps. Tappi Journal volume 79,
no. 3, pg. 167. TAPPI Press, Atlanta. March 1996.
7. Libby, C. E. ET all. Pulp and Paper Science and Technology. Volume II, Paper.
McGraw-Hill, New York. 1962.
8. Phillip, P., ET all. Celulose e Papel, Volumes I and II. IPT - Instituto de Pesquisas
Tecnológicas do Estado de São Paulo, São Paulo, 1988.
9. Spangenberg, R. J., ET all. Secondary Fibre <strong>Recycling</strong>. TAPPI Press, Atlanta. 1993.
10. Von Zuben, F. <strong>Recycling</strong> of Tetra Pak Cartons. Tetra Pak Ltda. Brazil, 1997.
33

ANNEX I – Report on Black Clawson’s trials in 1996
Upgrading carton Stock
By: Colin S. Bowser
The Black Clawson Company
Shartle Division –Technology Center – Middletown, Ohio
Report 37033
June 21, 1996
Objective:
The objective of <strong>the</strong> trial was to demonstrate <strong>the</strong> upgrading of a poly and foil covered
carton stock using secondary fibre processing technology.
Summary:
Th client supplied two bales of post-consumer milk and juice carton stock and one bale
of shredded post-industrial stock as furnish for trials. Two separate 8-foot Hi-Con
Hydrapulper batches were pulped for two different trials. A blend of <strong>the</strong> shredded and
unshredded was used for each. The pulped stock was extracted through an under rotor
bedplate having 3/8 inch holes. Residual plastics retained in <strong>the</strong> pulper after extraction
was diluted and fed to <strong>the</strong> Selectpurge for washing and dewatering.
Coarse and fine screening were demonstrated on <strong>the</strong> stock from <strong>the</strong> initial pulper batch
with a model 100 Ultra-V pressure screen. A 0.062” UP screen cylinder was used to
demonstrate coarse screening. Fine screening of <strong>the</strong> coarse screen accepts was
conducted with a 0.008” PSP cylinder screen. The accept stream from <strong>the</strong> fine screen
was collected for fur<strong>the</strong>r processing.
Fine screening was followed by through flow centrifugal cleaning with a single 3” X-
Clone to remove low specific gravity contaminants. Accept stock from <strong>the</strong> X-Clone was
forward centrifugal cleaned through a 3” Ultra-Clone to remove high specific gravity
contaminants. This concluded <strong>the</strong> trial on <strong>the</strong> first pulper batch.
The second pulper batch was coarse screened as <strong>the</strong> first. Coarse screen accepts were
<strong>the</strong>n washed and thickened using a model 100 DNT washer and Fibercone Press in
sequence. The press thick stock was collected in Gaylord boxes.
Samples were collected from all equipment demonstrations. Tests performed on <strong>the</strong>
samples included consistency, freeness, dirt, brightness, strength tests and beater
curves. The test results, complete equipment operating data and observation
handsheets are included in this report.
34

Hydrapulper:
Pulping for each trial was conducted in an 8’ diameter Hydrapulper fitted with a 40”
diameter Hi-Con rotor. Batch one consisted of a blend of 610 air-dry pounds unshredded
and 290 air-dry pounds shredded poly and foil covered carton stock. These were added
to 900 gallons of water at 70 o F. Batch two was a blend of 601 air dry pounds
unshredded and 282 air dry pounds shredded poly and foil covered carton stock. These
were added to 700 gallons of water at 70 o F. Both batches were pulped approximately
35 minutes and extracted through a 3/8” drilled hole bedplate. Residual plastics and foil
retained in <strong>the</strong> pulper after extraction were diluted and fed to <strong>the</strong> Selectpurge for
washing and dewatering. Due to large sheets of plastic in <strong>the</strong> initial pulper batch <strong>the</strong>re
was difficulty feeding <strong>the</strong> plastics through <strong>the</strong> small diameter pipes in <strong>the</strong> pilot plant.
The second batch, having no large sheets of plastic, was easily processed through <strong>the</strong>
Selectpurge.
Batch #1 #2
Date April 29, 1996 May 2, 1996
Rotor Diam. / type 40” – Hi-Con 40” – Hi-Con
Rotor Speed 290 rpm 290 rpm
Bedplate holes 3/8” 3/8”
Connected hp 200 200
Furnish – unshredded/ shredded 610 lb / 290 lb 601 lb/ 282 lb
Water volume 900 gal 700 gal
Water temperature 70 o F 70 o F
Chemicals used None None
Sample time 35 min 35 min
Stock consistency 13.3% 14.37%
Residuals left (air dried) - 205 lb (23.2% by weight)
Aspect of <strong>the</strong>
residuals after
pulping.
35

Coarse Screening: The initial pulper batch was diluted to 2.63% consistency in
preparation for coarse screening. Coarse screening was accomplished using a Model 100
Ultra-V Screen fitted with a 0.062” UP screen cylinder. Screening was done in a closed
loop with accept and reject flows returning to <strong>the</strong> fed tank. Once parameters stabilised,
samples were collected and <strong>the</strong> accept flow was diverted to a holding tank while rejects
were sewered. Screen accepts were <strong>the</strong>n fine screened.
The second pulper batch was coarse screened in <strong>the</strong> same manner as <strong>the</strong> first, however
<strong>the</strong> feed consistency was 1.99%. Coarse screen accepts were collected in a holding tank
and <strong>the</strong>n washed. Coarse rejects were sewered.
Batch #1 #2
Cylinder hole / type
0.062” / UP
Rotor type / foils number
Drum – 3 foils
Rotor Speed 645 rpm 650 rpm
Consumed hp 31 19
Connected hp 100 100
Freeness (feed) 529 CSF 630 CSF
Freeness (accept) 540 CSF 601 CSF
Freeness (rejects) 586 CSF 687 CSF
Flow rate (feed) 650 gpm 505 gpm
Consistency (feed) 2.64% 1.99%
Hydraulic reject rate 20.8% 20.0%
Fine Screening: A model 100 Ultra-V Pressure screen fitted with an 0.008” PSP slotted
cylinder and LowPower Rotor accomplished <strong>the</strong> fine screening. Coarse screen accepts
from <strong>the</strong> first trial were diluted to 1.46% consistency for fine screening. The screen was
operated in a closed loop. Samples of <strong>the</strong> feed, accept and reject streams were collected
for testing. The accept flow was <strong>the</strong>n diverted to a holding tank and <strong>the</strong> rejects were
sewered. Fine screen accepts were <strong>the</strong>n prepared for cleaning.
Batch #1
Cylinder slot / type
0.008” / PSP
Rotor type / foils number
LP 1 – 3 foils
Rotor Speed
780 rpm
Consumed hp 26
Connected hp 100
Freeness (feed)
503 CSF
Freeness (accept)
476 CSF
Freeness (rejects)
570 CSF
Flow rate (feed)
630 gpm
Consistency (feed) 1.46%
Hydraulic reject rate 20.6%
36

Centrifugal cleaning: Fine screen accepts were diluted to 0.87% consistency and heated
to 120 o F. The stock slurry was <strong>the</strong>n pumped to a single 3” X-Clone cleaner. The X-Clone
was operated at an inlet pressure of 26 psi with a differential pressure of 15 psi between
<strong>the</strong> feed and accept screens. X-Clone accepts were collected in a holding tank and <strong>the</strong>
rejects were sewered. Samples were taken for laboratory analysis. X-Clone accepts were
pumped to a single 3” Ultra-Clone cleaner. The Ultra-Clone was operated at an inlet
pressure of 35 psi with a differential pressure of 20 psi between <strong>the</strong> feed and accept
streams. Samples were collected with stable operating conditions. This concluded <strong>the</strong>
trial on <strong>the</strong> initial pulper batch.
Batch #1 #1
Cleaner type X-Clone Ultra-Clone
Cleaner Size 3” 3”
Feed pressure 26 psi 35 psi
Accept pressure 11 psi 15 psi
Delta P 15 psi 20 psi
Freeness (feed) 516 CSF 523 CSF
Freeness (accept) 524 CSF 437 CSF
Freeness (rejects) - 610 CSF
Flow rate (feed) 44 gpm 50 gpm
Consistency (feed) 0.87% 0.97%
Hydraulic reject rate 9.77% 12.3%
Washing: A Model 100 DNT Washer with a Trio Tech 114 wire operated at 3,000 ft/min
was used to wash <strong>the</strong> coarse screen accept from <strong>the</strong> second trial. The stock was fed at
280 gallons per minute at 1.86% feed consistency. DNT thick stock was fur<strong>the</strong>r
thickened in a Fibercone Press and <strong>the</strong> DNT filtrate was sewered. The Fibercone Press
thickened <strong>the</strong> stock to 26%. The press thick stock was collected in Gaylord boxes. The
press filtrate was sewered. Samples were taken around <strong>the</strong> washer and <strong>the</strong> press.
Batch #2
Connected hp 100
Freeness (feed)
592 CSF
Freeness (accept)
702 CSF
Freeness (rejects) -
Flow rate (feed)
280 gpm
Consistency (feed) 1.86 %
Consistency (accept) 10.42 %
Consistency (reject) 0.14 %
Hydraulic reject rate 83.3 %
37

Dirt Count and Brightness Results – Batch #1
PPM
50
45
40
35
30
25
20
15
10
5
0
46.5
Coarse Screen
1.6mm
30.8
Fine Screen
0.2mm
Accepted stock
19.9
Through-flow
cleaners 3"
6.4
Forward
cleaners 3"
From <strong>the</strong> same samples, paper sheets were made from cleaned <strong>fibres</strong> and sent to Miami
University in Oxford, Ohio, which reports are shown on <strong>the</strong> charts below.
500
450
400
350
300
250
200
150
100
50
0
Freeness (CSF)
Tensile Index (N.m/g)
0 5 10 15
Beating time (min)
14
12
10
8
6
4
2
0
Tear Index (mN.m2/g) Burst Index (kPa.m2/g)
Breaking Length (km)
0 5 10 15
Beating time (min)
Note: Please contact <strong>the</strong> author at mario.abreu@tetrapak.com if you need copies of detailed reports from
<strong>the</strong> Miami University and copies of handsheets from <strong>the</strong>se trials.
38

ANNEX II – Report on Celleco’s trials in 1998
Tetra Pak Carton Systems AB, Lund, Sweden
and
Alfa Laval Celleco Inc., Lawrenceville, GA
Repulping Characteristics Of Italian OCC Mixed With TBA
OBJECTIVE: To test <strong>the</strong> repulping properties of Italian OCC when combined with limited
quantities of Tetra Brik® Aseptic Packaging.
Test Date: April 13-17, 1998
Release Date: June 22, 1998
Written By: Brian Alton
Laboratory Report: # 98 317
EXECUTIVE SUMMARY
OBJECTIVE
The objective of <strong>the</strong> present study was to examine <strong>the</strong> response of OCC when repulped
with pre- and post-consumer Tetra Brik® Aseptic (TBA) packaging.
MATERIALS TESTED
1. Pre-consumer Tetra Brik® Aseptic packaging obtained from Tetra Pak training center in
Italy.
2. Post-consumer Tetra Brik® Aseptic packaging obtained from pilot scale collection
programs in Italy
3. OCC material received from <strong>the</strong> paper mill Cartiera Dell’ania S.p.A in Italy.
CONCLUSIONS
1. The addition of TBA to <strong>the</strong> OCC material improved <strong>the</strong> physical properties of <strong>the</strong>
resulting repulped mixture, as well as increasing brightness and lowering dirt
counts.
2. Longer pulping time improved <strong>the</strong> physical properties of each mixture but had a
negative effect on <strong>the</strong> dirt count of <strong>the</strong> resulting material.
3. Increasing <strong>the</strong> percentage of TBA in <strong>the</strong> pulper batches fur<strong>the</strong>r improved <strong>the</strong>
physical properties of <strong>the</strong> final product, but also increased dirt counts in <strong>the</strong> final
product.
39

BACKGROUND
European countries have been recycling OCC for many years. As a result, present-day
OCC in Europe consists of shorter <strong>fibres</strong> than its American counterpart, hence creating a
weaker final product. This study was developed to determine if Tetra Brik® Aseptic
packaging material could be added to <strong>the</strong> pulping batches to increase <strong>the</strong> strength of
<strong>the</strong> final product without a detrimental effect on its cleanliness.
TEST PROCEDURES
Pulper batches consisting of 1000 lb. of material (<strong>the</strong> composition of <strong>the</strong> individual
pulper batches is outlined in Table 1 on <strong>the</strong> next page) were placed in <strong>the</strong> pulper and
water was added to reduce <strong>the</strong> consistency to approximately 13% BD consistency. Each
pulper batch was pulped for <strong>the</strong> time indicated in Table 1, <strong>the</strong>n was discharged to <strong>the</strong>
dump chest. Any debris remaining above <strong>the</strong> extraction plate was discharged to <strong>the</strong>
trommel (drum) screen, from which <strong>the</strong> accepts also went into <strong>the</strong> dump chest.
The dump chest was <strong>the</strong>n diluted to approximately 1.8% and <strong>the</strong> contents transferred to
<strong>the</strong> coarse screen feed tank. The coarse screen accepts went forward to <strong>the</strong> cleaner
feed tank while <strong>the</strong> rejects were sewered. The cleaners were operated in recirculation
mode until samples were taken (<strong>the</strong> accepts were double-sampled so that one sample
could be sent to an external lab for physical properties testing), and <strong>the</strong> feed tank was
<strong>the</strong>n drained. All tanks in <strong>the</strong> process were drained and hosed out, and <strong>the</strong> next pulper
batch was placed in <strong>the</strong> pulper for testing. Due to process limitations, pulper batches
were not initiated until <strong>the</strong> majority of <strong>the</strong> stock from <strong>the</strong> preceding test has been
removed from <strong>the</strong> system. This procedure was repeated until all six tests were
complete. At <strong>the</strong> conclusion of <strong>the</strong> sixth test, one pulper batch was made up which
consisted only of TBA. Only <strong>the</strong> pulper was used for this test (Test 7), and <strong>the</strong> sample
that was taken was sent with <strong>the</strong> six cleaner accept samples to <strong>the</strong> external testing lab
(IPST) for physical properties testing. At IPST, <strong>the</strong> Test 7 sample was screened, <strong>the</strong>n
refined. Both <strong>the</strong> unrefined and refined post-screening pulps were subjected to physical
properties testing, <strong>the</strong> results of which appear later in this report as T7 and T7-1300,
respectively. All results for Tests 1-6 refer to analysis performed upon <strong>the</strong> cleaner
accept samples.
For analysis and reporting purposes, <strong>the</strong> accepts samples from <strong>the</strong> CLP700LD cleaners
(#1P ACC) were considered <strong>the</strong> final product. All results refer to <strong>the</strong> analysis performed
on <strong>the</strong>se samples, unless o<strong>the</strong>rwise noted. As <strong>the</strong> Alfa Laval Celleco laboratory does not
have <strong>the</strong> capacity to perform physical properties testing, an extra set of each of <strong>the</strong>
cleaner accept samples were taken during <strong>the</strong> trial and sent to IPST, who performed <strong>the</strong>
physical properties tests. Thus <strong>the</strong> analyses were performed as follows: ALC performed
<strong>the</strong> consistency (T240); Somerville (UM242); CSF (T227); ash (T211); Kajaani and
sticky/plastic counts (Celleco standard methods). IPST performed <strong>the</strong> analysis for
brightness (T452); tear (T414); tensile, stretch, TEA, modulus, tensile index, and
breaking length (T494); dirt count (T213, T437); and <strong>the</strong>ir own ash testing (T-211). All
test numbers in paren<strong>the</strong>ses refer to TAPPI test methods.
40

Table 1
Pulper Test 1 Pulper Test 2 Pulper Test 3
% CNS: 15 % CNS: 15 % CNS: 15
Temp: Ambient Temp: Ambient Temp: Ambient
Time: 15 min Time: 15 min Time: 30 min
Chemical: None Chemical: None Chemical: None
Hole size: 6 mm Hole size: 6 mm Hole size: 6 mm
OCC 100% OCC 85% OCC 85%
TBA* 0% TBA* 15% TBA* 15%
Pulper Test 4 Pulper Test 5 Pulper Test 6
% CNS: 15 % CNS: 15 % CNS: 15
Temp: Ambient Temp: Ambient Temp: Ambient
Time: 30 min Time: 15 min Time: 15 min
Chemical: None Chemical: None Chemical: None
Hole size: 6 mm Hole size: 6 mm Hole size: 6 mm
OCC 100% OCC 75% OCC 50%
TBA* 0% TBA* 25% TBA* 50%
*The material called “TBA” consists of equal parts of pre- and post-consumer Tetra
Brik® Aseptic packaging.
Process Specifications
Trommel Screen Coarse Screen 1 (CS1) #1P cleaner header
Hole Size: 8 mm Rotor: Tapershear Cleaner type: 700LD
Shower 75.7 lpm Clearance: 0.32 mm Cleaner #: 3
Drum speed: 12 rpm Tip Speed: 70 Feed psig: 29 psig
Drum dia.: 947.74 mm Basket type: Hole Accept psig: 8 psig
Drum length: 2438.4 mm Basket size: 1.4 mm % RRv (HWR): 8
Accept lpm: 1211.2 % RRv (LWR): 15
Reject lpm: 204.39
Dilution lpm: 68.13
RESULTS (Physical Properties)
Test Tear Tensile Stretch TEA Modulus CSF Ash †
mN KN/m % J/m 2 N/mm ml %
1 656 2.48208 1.94 32.53581 304.89642 243 10.45
2 738 2.49958 2.12 36.83071 295.31259 274 9.4
3 718 2.69706 2.2 42.57083 316.12332 298 10.17
4 721 2.54572 1.98 35.31547 311.39061 304 9.92
5 756 2.73039 2.12 40.88524 336.2633 347 8.82
41

6 760 2.77789 2.08 41.24317 345.05747 367 7.67
7 673 2.14292 1.42 21.47151 326.43168 * *
7-1300 891 3.59327 2.56 63.24187 390.28271 * *
RESULTS (Contamination Levels)
Test CNS Somerville Kajaani Stickies Plastics PPM Brightness
% % debris Mm count count mm 2 /m 2 %
1 0.74 0.42 1.31 57 46 34.21 29.56
2 0.79 0.62 1.37 91 71 23.66 32.13
3 0.8 0.42 1.4 67 52 25.7 32.58
4 0.82 0.45 1.36 87 41 43.14 30.42
5 0.85 0.58 1.43 62 67 37.2 33.64
6 0.84 0.56 1.44 59 118 40.85 33.11
7 * * * * * 13.98 41.19
7-1300 * * * * * ** 37.53
* These analyses were performed at <strong>the</strong> ALC lab, which did not analyze samples T7 or T7-
1300.
**Dirt counts were not performed after refining of <strong>the</strong> T7 sample.
† Ash testing was performed at both <strong>the</strong> ALC lab and at IPST. Comparison of <strong>the</strong> values
revealed that <strong>the</strong> IPST numbers were significantly lower than <strong>the</strong> ALC numbers. This
discrepancy was resolved by <strong>the</strong> revelation that IPST performed <strong>the</strong>ir ash testing from
handsheets, whereas <strong>the</strong> ALC lab used consistency pads with ashless filter paper, which
would retain more ash than a handsheet mold. The ALC numbers are reported here.
The IPST numbers appear with <strong>the</strong> raw data at <strong>the</strong> end of this report.
Power Draw
Test Initial 30 sec Final
1 115 N/A 117
2 160 130 120
3 160 130 120
4 160 130 116
5 170 150 131
6 170 150 130
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Test Breaking Tensile Tear E-Modulus
length Index Index (MPa)
km N.m/g mN.m 2 /g N/mm 2
1 3811 37,4 9,9 2595
2 3846 37,7 11,1 2039
3 4152 40,7 10,8 2468
4 3883 38,1 10,8 2087
5 4139 40,6 11,2 2585
6 4247 41,6 11,4 2585
7 3294 32,3 10,1 2499
7-1300 5412 53,1 13,2 3412
60%
50%
40%
30%
20%
CSF (ml)
TEA (J/m2)
Tear (mN)
Tensile (kN/m)
10%
0%
100% OCC 15% TBA 25% TBA 50% TBA
Increase on properties due to blending OCC with <strong>fibres</strong> from TBA cartons
DISCUSSION
As can be seen from <strong>the</strong> table of physical properties results, <strong>the</strong> addition of TBA to <strong>the</strong> OCC
had a positive effect on <strong>the</strong> strength of <strong>the</strong> resulting final product. In fact, greater
percentages of TBA in <strong>the</strong> mixture improved sheet strength even fur<strong>the</strong>r. Increasing <strong>the</strong>
amount of TBA also had a positive impact on sheet appearance in terms of brightness gain
and lowered dirt counts. However, <strong>the</strong> tests containing 25% and 50% TBA by weight had
elevated dirt counts compared to <strong>the</strong> 15% batches.
On <strong>the</strong> whole, <strong>the</strong> thirty-minute pulper batches had better physical properties than <strong>the</strong>
fifteen-minute batch of <strong>the</strong> same mixture. Conversely, <strong>the</strong> dirt counts were higher after
thirty minutes of pulping than after fifteen for a given batch composition, though <strong>the</strong>
brightness did not change appreciably.
43

Allowing for material variance between pulper batches, <strong>the</strong> sticky contaminant levels were
relatively constant throughout all tests, while <strong>the</strong> level of plastic contaminants in <strong>the</strong> final
product was higher in those batches containing TBA, and was roughly proportional to <strong>the</strong>
percentage of TBA in <strong>the</strong> mixture. Average fibre length also increased as <strong>the</strong> amount of
TBA present in <strong>the</strong> pulper batch increased, and slurry freeness rose accordingly. Ash levels
were seen to be lower in those mixtures containing TBA. The Somerville debris levels in
<strong>the</strong> final product increased when TBA was added, but were lowered by increasing <strong>the</strong> time
of pulping.
Pulper amp draw was greater for those batches containing TBA, and batches with greater
percentages of TBA drew higher amp loads than those with lower percentages of TBA.
The low initial amp reading of <strong>the</strong> first pulper is a result of a large portion of material that
had not fully engaged <strong>the</strong> rotor at <strong>the</strong> time of <strong>the</strong> initial amp reading. After this portion of
material engaged <strong>the</strong> rotor, <strong>the</strong> amp reading rose, but due to <strong>the</strong> fact that <strong>the</strong> remainder
of <strong>the</strong> material had undergone some pulping, this amp value remained as it was recorded.
44