TECHNICAL PAPER #53
UNDERSTANDING PAPER RECYCLING
By
John Vogler & Peter Sarjeant
Technical Reviewers
Philip Barr
Dr. I. B. Sanborn
Dr. Robert Brooks
William Burger
VITA
Published By
VOLUNTEERS IN TECHNICAL
ASSISTANCE
1600 Wilson
Boulevard, Suite 500, Arlington, Virginia 22209 USA
Telephone: (703) 276-1800, Fax: (703) 243-1865
Telex: 440192 VITAUI, Cable: VITAINC
Internet:
vita@gmuvax.gmu.edu, Bitnet: vita@gmuvax
Understanding Paper Recycling
ISBN: 0-86619-270-0
[C]1986, Volunteers in Technical Assistance
PREFACE
This paper is one of a series published by Volunteers in
Technical
Assistance to provide an introduction to specific
state-of-the-art
technologies of interest to people in developing countries.
The papers are intended to be used as guidelines to help
people choose technologies that are suitable to their
situations.
They are not intended to provide construction or
implementation
details. People are urged to contact VITA or a similar
organization
for further information and technical assistance if they
find that a particular technology seems to meet their needs.
The papers in the series were written, reviewed, and
illustrated
almost entirely by VITA Volunteer technical experts on a
purely
voluntary basis. Some 500 volunteers were involved in the production
of the first 100 titles issued, contributing approximately
5,000 hours of their time. VITA staff included Marjorie
Bowens-Wheatley
as editor, Suzanne Brooks handling typesetting and
layout, and Margaret Crouch as project manager.
The VITA Volunteers who wrote and reviewed this paper have
many
years of experience in the paper industry. Jon Vogler,
author of
Work from Waste, specializes in small-scale industries,
particularly
those based on recycled materials. Peter Sarjeant, dedicated
to keeping alive the processes of the old master
papermaker's
craft, is the author of Hand Papermakinq Manual. I. B.
"Bruce" Sanborn is associate director of research
and development
at Consolidated Papers, Inc.; Phil Barr is fiber logistics
manager
for the Weyerhaeuser Company; and Dr. Bob Brooks, also of
Weyerhaeuser, is the manager of pulp and paper educational
activities.
William Burger, retired mechanical engineer from
Kimberly-Clark
Corporation, assisted in the design of equipment for a
micro paper factory in Tanzania.
VITA is a private, nonprofit organization that supports
people
working on technical problems in developing countries. VITA
offers
information and assistance aimed at helping individuals and
groups to select and implement technologies appropriate to
their
situations. VITA maintains an international Inquiry Service,
a
specialized documentation center, and a computerized roster
of
volunteer technical consultants; manages long-term field
projects;
and publishes a variety of technical manuals and papers.
UNDERSTANDING PAPER RECYCLING
by Jon Vogler & Peter Sarjeant
I. INTRODUCTION
Papyrus, from which the word paper is derived, is known to
have
been in use as early as 3000 B.C. Developed in the Nile Valley,
it was made of strips cut from the papyrus plant stem,
soaked,
and laid, first lengthwise, then crosswise, to form a mat.
The
mat was then pounded and pressed into a thin sheet. Later,
similar processes elsewhere used other fibers such as silk.
True papermaking, which began in China about A.D. 105, uses
an
entirely different process than the preparation of papyrus.
It
begins with rags, straw, bark, wood, or other fibrous
materials
that are chopped or cut fine. The fibers are pounded or
pulped
until they are separated from each other and mixed with
water.
Then the fibers are lifted from the water in a sieve-like
screen
that allows the water to drain away, leaving a thin mat of
fibers.
The fiber mat, which can be dried in place or removed and
dried separately, becomes a sheet of paper.
The earliest recorded manufacture of paper is credited to
one of
the first "purchasing officers," Ts'ai Lun, head
of the Imperial
Supply Department of
Emperor Ho of China. Ts'ai Lun experimented
with a variety of
materials: vegetable fibers, old hemp, cotton
rags, old fishnets, and mulberry bark. The paper produced
was
cheap and durable
and the surface was good--and, significantly,
it was made of
recycled materials.
Early European papers were also made from recycled linen or
cotton rag. It was thick and rough, and the surface needed
to be
"sized" with gelatin or the ink soaked in. Ulman
Stromer set up
a mechanized papermill in Nuremberg, Germany, in 1390, using
water-powered hammers for beating the material, a method
already
used by the Chinese. The craft accompanied the early
settlers to
America.
True mechanization was not achieved until 1799, when the
Frenchman
Nicholas Robert built a machine with an endless wire mesh
and
a pair of squeeze rolls. The device was taken to England and
marketed by two stationers, the Fourdrinier brothers. In
1804,
Brian Donkin, a millwright-engineer, built the first
successful
papermaking machine, in Two Waters Mill, Hertfordshire,
England,
and another in America in 1827. Crude early designs improved
steadily. By the end of the nineteenth century, Fourdrinier
technology
was widespread; machines just over 2 meters wide supplied
25 metric tons per day to the growing market for newsprint.
Modern machines form paper in a continuous ribbon or web,
not a
single sheet at a time as did the ancients. A good
papermaker in
the olden days could make enough sheets in a day to weigh
about
90kg. Today, an average machine makes 90,000kg per day! Much
of
the paper produced ultimately ends up as waste paper,
mountains
of it in some areas, which can often be recycled into other
papers and paper products.
The recycling of waste paper is the
focus of this paper.
II. MODERN PAPERMAKING
FIBERS AND PULPS
Fibers are the fine, thread-like wisps from which paper,
textiles,
and many other materials are made. Tear a piece of paper
and the fibers can be seen at the torn edge (more clearly
with a
magnifying glass). Paper fibers are made of cellulose, the
basic
building material of plants and trees. These materials can
be
made into paper by pulping (breaking them down until the
fibers
are loose and free of the substances that bind them), then
reforming
them while wet and finally drying.
Softwood (or coniferous) pulps are used for tough wrapping
and
packaging papers because of their long fibers; deciduous or
hardwood pulps provide fine fibers for printing and writing
papers.
To understand the waste paper industry it is important to
know
about the major types of primary wood pulp used in
papermaking:
mechanical pulp, and chemical pulps, which include kraft
pulp,
and sulphite pulp. Pulp made of recyled paper is known as
secondary
pulp.
Mechanical Pulp
Mechanical pulps yield the most paper per ton of wood, but
are
the weakest. They are made by pounding or grinding cellulose
fiber, such as wood or sugar cane bagasse. One of the
commonest
uses of mechanical pulps is in the manufacture of newsprint.
Newsprint is relatively weak and loses its strength
altogether if
wetted--a characteristic of mechanical pulp. It is used for
rapid
newspaper printing because printing ink is soaked up and
dries
very quickly, but it lacks the permanence of paper made from
kraft or sulphite pulp. Strong chemical pulp is often added
to
mechanical pulp to give newsprint better strength.
Mechanical
Pulp often contains tiny particles of wood that have not
been
reduced to fiber and are visible to the naked eye, so paper
made
from it is described as "woody."
Chemical Pulps
A stronger paper product is most cheaply made by pulping
cellulose
fibers in such a way that they are not weakened by
mechanical
damage. The wood or stalks are first reduced mechanically to
small chips, then cooked at high pressure with chemicals
that
attack the bonds between the fibers. The chemicals most
commonly
used are:
1. Caustic soda and
sodium sulfate, which produce coarse, very
strong papers
known as kraft, suitable for paper sacks and
boxes that hold
heavy weights.
2. Various sulfides
(such as ammonium and calcium), which
produce finer fibers,
suitable for making high quality,
strong (but
expensive) printing and writing papers (usually
bleached white).
Secondary Pulp
Secondary or recycled pulp is made by vigorously agitating
wastepaper
in water (usually in a hydro-pulper, a tank containing
rotating blades) to separate the fibers bonded during the
original
papermaking process. As these bonds are weaker than those of
the original cellulose plant, hydro-pulping is a more gentle
process than primary wood pulping and consumes less energy.
Even
so, each time paper is recycled it becomes weaker. Secondary
Pulp is therefore never as strong as the primary fiber from
which
it was made. It can be almost as good, provided pure waste
paper
of the same type is used. For example, pulp made by
hydro-pulping
clean kraft sacks will make new sacks of only slightly lower
quality, particularly if mixed with a proportion of primary
kraft
Pulp. If, however, the secondary pulp is made from material
that
contains newspapers or quantities of dirt, dust, or clay, it
w.11
not be strong enough to make sack paper.
Coated Papers. In some cases the matted, absorbent surface
of a
paper is coated with a material that makes it glossy and
smooth.
This coated paper is better for printing. Coated papers are
frequently used in magazines that are financed by the
advertisements
printed. In the process of hydro-pulping coated wastepaper,
the coating is washed out; thus, the weight of fiber
obtained from a ton of coated paper is less, often by 20
percent,
than that obtained from a ton of uncoated paper. As a
result, the
value of scrap coated paper to the paper mill, and its
selling
price, will be lower.
If the coating is plastic or other material that will not
disperse
in water, the waste paper will require specialized machinery
to recycle it and may reduce the value of more pure paper
with which it is mixed. The same is true of polyethylene
film,
cellophane, glued paper, string, and any material that will
not
break down in water. Some of the various coated papers can be
kept warm and wet in storage, then cooked in a hot caustic
solution
in order to biodegrade and break down the coating to release
the fibers. Again, these papers require special machinery
and
handling to recycle and they may not be as valuable as
simpler,
plain papers.
Printed and Colored Papers. Both printing and tinting reduce
the
value of papers to be recycled. They make the pulp and the
paper
made from it dull grey in color unless bleached, which is
expensive,
or de-inked, which is also expensive. Tinting colors the
pulp, which must then either be used for a limited range of
similarly colored products (or cheap, grey products), or
must be
bleached. Therefore, white waste paper is more valuable than
similar material that is colored. Unprinted waste paper is
of a
greater value than the same material printed.
STRUCTURE OF THE PAPERMAKING INDUSTRY
A review of the papermaking industry is needed to understand
the
ways in which waste paper is used. The manufacture and use
of
paper is one of the world's biggest industries; it takes
place
in:
1. pulp mills, which
process wood chips or other materials to
make pulp;
2. paper mills and
board mills, which use pulp or waste paper to
produce finished
paper and board;
3. paper converters,
which use paper or board to produce boxes,
tubes, rolls of
tissue, boxes of blank office paper, stacks
of printing paper
cut to standard sizs, etc.;
4. printers, who
usually buy from converters, although larger
firms such as
newspaper presses may buy directly from the
paper mills; and
5.
"integrated" mills, which make pulp and then use it themselves
to make paper.
These industries are huge, highly mechanized, and efficient.
There are many of them, so they compete fiercely for the
available
markets. In countries where huge markets, skilled managers
and technicians, and the massive capital needed for
investment
are available, handmade and small-scale paper manufactureres
find
it very hard to compete. Large or small, where these
industries
exist they represent potential markets for recycling waste
paper--particularly
in developing countries which may lack other
resources for producing pulp.
III. WASTE PAPER COLLECTION
TYPES OF WASTE PAPER
Collecting waste paper is only difficult in a few poorer and
more
rural parts of the world. Elsewhere it is abundant. Selling
it is
often far more difficult, and only those who thoroughly
understand
stand the market are successful. The different types of
wastepaper
will therefore be considered in relation to their markets,
starting with the most valuable, and going on to those of
less
value.
Printing and Writing Papers
This category includes the best quality, most expensive
papers
that bring the highest waste paper prices. They are mainly
made
from bleached kraft and sulphite pulps. They are listed here
in
descending order of value.
Computer printouts. This is usually used to make high
quality
printing and writing papers.
Computer punched cards (tab cards). These may be
buff-colored,
the most valuable, or colored.
Printer trimmings. These are the edge trimmings left when a
printer, boxmaker, or converter cuts the product to its
final
size. Their high value results from cleanness, lack of
printing,
and quality of the material. The value is increased if the
printer has kept different grades separate. If not, it is
usually
worthwhile for the collector to sort the paper into
different
grades and separate the printed material from the unprinted.
This
labor-intensive activity needs no investment and can create
many
jobs. White trimmings should be sorted from colored, but
different
colors need not be separated. All may be sold to makers of
printing and writing papers.
Office papers. Such papers as invoices, ledgers, letter
papers,
and record cards are included in this group. Printed or
written
on papers are separated from blank paper, and whites are
separated
from colors. Carbon paper and self-duplicating paper are
also
separated from the rest.
Grease proof and plastic-coated papers, file covers and bookbindings,
metal file clips, string, and other office materials should
be removed. For sales to a big mill it is unnecessary to
remove
staples or paper clips as the mill will remove these with
magnets;
smaller mills may reject them. Envelopes, including a few
of the cheaper manilla variety (light brown), can be mixed
in
with whites, as can cream-colored envelopes and papers in
any
quantity. Adding machine rolls are usually good, white and
unprinted.
Office papers may be sold to makers of printing paper
and high quality board.
School and letter papers. Letter papers may be of good
quality,
but school exercise books are low in value, although they
often
contain little ink (faint ruling does not count), because
they
are mostly of mechanical pulp. They can be sold to makers of
printing and writing papers.
Pamphlets and magazines. Known in the trade as
"pams," these are
the lowest grade of (printing) papers other than newsprint.
They
are often coated and have heavy printing and large amounts
of
color. They are not worth sorting unless a paper mill has a
Particular demand. They are heavy and it is easy to collect
a
great weight quickly. They are best sold to makers of low
quality
board.
Newspapers. In some countries, newspapers are little in
demand
due to their low strength. Telephone directories and some
magazines
are also made from newsprint. Their principal uses are as
mixed waste paper for the manufacture of cheap flutings,
grey
board (cheap cardboard), or the middle layers of multilayer
boards. There are three important exceptions:
o In poor countries
where little is thrown away, even low
quality raw
materials are in short supply.
o Some countries
that are heavily industrialized but lack
their own sources
of mechanical pulp, operate "de-inking
plants."
These remove ink from old newspapers by washing or
bleaching. If such
plants exist, or if it is economical to
ship to countries
that have them, prices for newspapers may
be higher.
o Unprinted
newsprint is discarded by the newspaper presses,
as are trimmings
from the sides of the paper and reel ends
(the material at
the center of the reel of newsprint, which
cannot be used for
technical reasons). The former can be
sold back to
manufacturers of newsprint and low quality
writing paper. The latter is clean and large
enough to be
cut up and sold at
a high price for food wrappings.
Packaging Papers
Several types of packaging papers may be collected and
recycled.
Again, they are described here in descending order of their
value.
Kraft Sacks. Kraft paper is recognized by its strength and
brown
color. It is used for large sacks, in two or three ply
thicknesses,
or for smaller bags and wrapping papers. Occasionally,
whitish,
bleached kraft is used. Watch out for sacks with
polyethylene
linings, often used to protect chemicals from damp, which
are frequently reinforced with canvas or similar material.
Tarred
Papers (waterproof) are unmarketable and reduce the value of
the
load. Be sure sacks are empty.
An important decision is whether a greater profit can be
made by
selling kraft for re-use as sacks or to board or kraft paper
mills for pulping. Re-use may entail repair or more sorting,
transportation, and selling costs, but this usually pays
off.
Corrugated Cardboard. This is a brown board made of three
layers.
The flat top and bottom layers are called liners and the
corrugated
(wavy) center is the fluting. The liners are often made of
primary kraft, sometimes with secondary material (e.g.,
kraft
sacks or old corrugated boxes) mixed in. The fluting is made
from
low quality material. Its function is to give stiffness to
the
wall of the finished box. Pulp for fluting manufacture may
have a
high proportion of mixed waste paper. Corrugated board is
used to
make packing boxes or cartons and these are in demand
everywhere.
Where there is no board mill, boxes can often be sold for
re-use.
They are rarely contaminated with impurities, though some
corrugated
board and sack paper has been treated with an invisible
resin, which gives it superior strength when wet. This
material
will cause problems for the paper mill, since it will be
very
hard to repulp. As a result, the value of this otherwise
attractive
waste paper will be lower.
Special Packaging and Wrapping Papers. These come last in
the
order of value because of the problems they cause with
impurities,
or contraries. Much modern packaging mixes plastics, metals,
and other materials with paper and board, and it is
difficult
or uneconomical to separate them. Greaseproof, cellophane,
and "wet strength" papers do not break down in
water, cannot be
pulped, and are difficult to recognize and remove. The main
material is cardboard, containing a high proportion of cheap
grey
board (sometimes inside an outer layer of good quality).
'he
amount of color printing is high too. Therefore, although
such
papers or boards are expensive to produce, their value as
waste
is no higher than that of mixed waste paper and may be lower
due
to contraries.
Mixed Waste Paper
Mixed waste paper is the lowest usable grade, and may have
almost
any composition. Grey board or multilayer board and similar
packaging materials not acceptable in any other grade, as
well as
mixed, unsorted grades are satisfactory. A number of points
are
worth noting:
o This is the
material often collected from municipal (town)
garbage dumps by
scavengers, or at specially built composting
or refuse-sorting
plants.
o In a district of
offices, factories, or wealthy homes, mixed
waste paper may
contain valuable grades, worth sorting out
for separate sale
if labor costs are low or time is available.
It is important to
realize that the material left,
after better
grades have been removed, may bring a lower
price. This
leftover material is principally made up of
newspapers,
packaging, and cheap cardboard. However, if
local mills make
corrugated board, toilet tissues, and cheap
grey board, then
separated kraft sacks, brown paper, and old
cartons can go to
the first and printing and writing papers
to the second. These can be sold for higher
prices and will
not reduce the
price of the remainder for making grey board.
o Mixed waste paper
can be an important source of material for
recycling because,
although merchants may have cornered
supplies of high
quality materials such as kraft, corrugated
cartons, and
printing and writing papers, quantities
of mixed waste
paper may still be obtained from municipal
refuse by those
who know what is valuable and what is not.
o Opportunities
exist here for creating more jobs. Once the
principles of
sorting have been taught, the work requires
neither capital,
technical skill, nor bodily strength and
may be undertaken
by the disabled or mentally retarded.
o Mixed waste paper
is worth half to a third of the value of
old cartons, and
this value is reduced if it is dirty, as
is most material
extracted from refuse dumps. By sorting
out the higher
grades and selling to the right market, a
value equal to
that of cartons may be achieved. The gain,
however, has to be
compared with the time and cost of sorting,
selling, and
transporting to several markets instead
of only to one.
SOURCES OF WASTE PAPER
Waste paper can be collected from the following places,
starting
with that which is likely to be the most profitable:
Computer offices produce the most valuable of all.
Printing shops usually sell the trimmings themselves, or
else
they are collected by a merchant.
Newspaper presses almost always sell the edge trimmings and
reel
ends themselves.
Offices throw out quantities of blank paper as well as
office
records, letters, etc. If offices are small or located away
from
the city center, they may not have made arrangements to sell
their waste.
Warehouses receive goods in sacks and corrugated boxes and
often
discard these after unpacking. Quantities may be large.
Factories may also have large quantities of packaginq that
they
do not want. These will get dirty on the factory floor
unless
rescued.
Shops receive goods in cartons; supermarkets and food stores
often give or sell these to their customers. Small shops may
not
Produce enough to make a visit worthwhile unless there are
other
shops nearby.
Householders may sell their waste paper. It may be dirtied
by
food waste or ashes and may
not be in large enough quantities to
make a visit worthwhile. Still, thousands of people in many
countries make a living by collecting household waste paper,
sometimes paying the householder a small sum.
Refuse dumps receive only the paper that no one else has
collected.
Refuse collectors often keep saleable materials, but
quantities of good quality waste paper continue to arrive at
refuse dumps all over the world.
WASTEPAPER HANDLING
Transportation
Some method of transporting the collected material is
essential.
This may be:
o Sacks
o Handcarts
o Handcarts
supported by a vehicle. When full, each cart is
wheeled to the
pick-up point, material is transferred to a
vehicle, and the
cart returns to collection. A good balance
might be six carts
to one vehicle.
o Horse-drawn carts.
For the stop-go process of waste paper
collection, this
is not "old fashioned" but highly effective.
o Motor vehicle.
Vans and trucks are a very expensive way of
collecting any but
the most valuable grades. With a wire
mesh cage on top,
to increase the load, they may be more
economical.
o Trailers. These,
also fitted with a cage top, make collecting
even more
profitable.
Cartons and boxes must be flattened before transport, by
treading
down or "baling."
Baling
Waste paper is baled to reduce the costs of transportation
and
storage. Baling involves squashing loose material into a
densely-
Packed, square-shaped bundle that is then strongly tied, in
two
or three directions, with wire or string.
Baling makes transport cheaper because a load of loose paper
will
overflow before it reaches the weight limit that the
vehicle an
carry. Baling makes storage cheaper because material, as
well as
being denser, can safely be stacked much higher.
Baling also reduces the risk of fire--a serious and
ever-present
risk in waste paper processing. Baling prevents air reaching
the
inside of the bundle, so flames only char the outside.
However,
baling does not totally remove the risk of fire,
particularly if
there is unbaled material lying around or if paper is wet,
which
causes it to ferment and the temperature to rise high enough
for
burning to begin.
Baling is most efficiently done in a press, a strong box
equipped
with some means of compressing the material and holding it
while
it is tied. In order of cost, this may be:
Treading Box: The simplest, cheapest baling press is a
strong,
hinged four-sided wooden frame with no top or bottom but a
joint
at one hinge. To operate, strong string is laid in the empty
box,
which is filled with paper, well trodden down. The string is
tied, then the box joint opened to release the bale.
Hand-powered mechanical presses are used to obtain higher
baling
pressures. Some use levers; some use screws with capstan
nuts
(nuts fitted with long turning arms); and some use steel
cables
wound (with a handle) around a spindle bearing a ratchet (a
device to keep the spindle from turning the wrong way). See
Figure 1.
upr1x11.gif (600x600)
Motorized screw presses can be used where electric power is
available. The press has a strong steel frame bearing an
electric
motor. The motor turns a vertical screw, which moves the
"platen"
(the strong, flat board that compresses the paper) up and
down.
Bales are so tight that thick wire must be used to bind
them.
Hydraulic baling presses can be built to almost any size and
power. They are expensive and need careful maintenance,
especially
in countries where there is desert sand or gritty soil
nearby,
but they are fast and very efficient. A wide range of
automatic
Controls and automatic wiring devices can be fitted onto the
press.
MARKETS FOR WASTEPAPER
The markets for waste paper may be any of the following:
Merchants, who buy from printers, converters, and small
collectors
and sell at a profit to the mills;
Exporters, who buy from anyone, to sell on the world market;
Mills, full-size industrial paper or board mills;
Papermakers, small-scale operations (usually plants
producing
less than 30 tons per day); and
Small industries that make high-quality paper by hand, or
that
use paper to make other products.
In countries where large-scale paper mills do not operate,
or
where subtantial amounts of products are imported, there may
be
opportunities to set up small-scale or even handmade
papermaking
industries. These processes are described in the technical
paper,
"Understanding Small-scale Papermaking." Readers
should be extremely
cautious about any plans to compete with the economics of
large-scale papermaking within any given country, as that
paper
makes clear. Other
possible uses of waste paper--other than for
repulping and paper production--are described below.
IV. ALTERNATIVE USES FOR WASTEPAPER
SHREDDED PAPER AS ANIMAL BEDDING
Banks, government agencies, and other organizations often
shred
waste paper into thin strips to prevent confidential
information
from being read. In England, this material is being marketed
as
bedding for animals. One commercial company, Shredabed
Limited,
markets both the material and the machinery for making it.
They
claim that:
1. Pigs bedded on this material keep cleaner.
2. Poultry gain a little more weight and suffer less
mortality
than birds bedded on wood shavings, straw, or sand.
3. Other livestock suffer less from respiratory (breathing)
problems when bedded on paper instead of straw.
4. Shredded paper is much easier to remove from pens and
stables
after use. It spreads easily on fields and breaks down to
form excellent manure.
5. Shredded waste paper is easy to bale; as a result, the
cost
of transportation and storage is low.
In cities where livestock sell for high prices, but straw or
other bedding materials are hard to obtain, this business
may
yield good profits, particularly if combined with an
operation to
sell the manure to gardeners.
EGG AND FRUIT BOXES FROM OLD CARTONS
A variety of strong, compartmented packing boxes can be
produced
from old, corrugated cartons with a small amount of
hand-operated
equipment (i.e., guillotine or paper shears, folder, punch
for
slotted tray pieces, and stapling machine).
The old cartons are cut down to accurate size, refolded, and
stapled. It is important that the trays fit exactly and do
not
move during transportation. To make the trays, off-cuts from
the
boxes are guillotined to a standard size and punched.
FRUIT AND EGG CARTONS FROM WASTEPAPER PULP
Another process makes egg cartons from paper pulp using a
small-scale
paper plant called the Super Melbourne. Waste paper is
first soaked, then pulped
and refined. Pulping can be done in a
domestic washing machine.
The equipment includes a refiner that reduces the pulp to
basic
fibers. The slurry that results is poured onto a sheet of
mesh
stretched over the forming tank of the Super Melbourne and a
valve in the tank is opened. The water draining from the
tank
sucks moisture from the layer of pulp, which is then pulled
from
the tank on its sheet of mesh. The layer of pulp is folded
over
once and pressed between specially shaped dies, then it is
laid
to dry.
The process employs four people but labor costs are reduced
when
Super Melbourne machines are batched together for greater
output.
Output is 60 egg trays per hour, or 60 sheets of paper 84 x
66
cm. The machine requires only 300 watts of electrical power.
Most
of the water used is recycled. Floor space required is two
square meters for the machinery and five square meters for
drying.
More sophisticated machinery is availale for producing form
200
to 4,000 30-egg trays or equivalent products per hour
Such a
machine is made by Tomlinsons, but careful market research
is
essential before contemplating the heavy cost of a machine
that
tends to saturate any but the largest market.
BUILDING MATERIAL
All over the world the poor use waste paper to construct
their
homes. It is cheap, and will offer protection from wind and
sun,
but there the advantages end. It does not resist water, is
highly
flammable, and is eaten by rats. It is also weak, tears
easily,
and rots or becomes brittle after a short time. It is an
unsuitable
material that demonstrates the desperate condition of those
who have no alternative. Asphalted paper, described below,
is a
great improvement.
ASPHALTED ROOFING SHEETS
Low-quality, low-cost roofing sheets with a life of about
five
years can be made from the very lowest grades of mixed waste
paper, grades that would not be acceptable for papermaking
due to
the amount of dirt and contraries present. A factory with
three
molding machines costs about $200,000 for plant and
machinery
and can produce about 8,000 sheets daily, each about one
square
meter in area (over two million square meters annually).
About 35
people are employed and 50 tons of paper per week are used.
In
India, the roofing material retails at around $0.25 per
sheet; in
South America, at about $0.60 per sheet. The manufacturing
process
consists of the following steps:
1. The waste paper
is washed and pulped in a hydropulper. A
mechanical
hammer mill or a Hollander beater may be used
instead.
2. The pulp is
passed through a screen, to remove dirt, grit, or
other
impurities, and a board-forming machine to produce a
continuous
length of board that is cut to length as it comes
off the machine.
3. The board is
spread on the ground and dried in the open air.
The edges are
trimmed on a rotating slitter.
4. The board passes
through an oven at the end of which are
corrugating
rollers. The corrugated sheets are then trimmed
again and
stacked in cradles.
5. Next, they are
dipped in a bath of hot asphalt. (Asphalt is
flammable so the
means of heating must be carefully chosen.
The asphalt
hardens rapidly at air temperature and the sheets
are unloaded and
stacked.
6. When quite hard
the sheets are either:
o
taped in bundles for sale as third quality;
o
sprinkled with mineral chips (while asphalt
is soft) prior
to packing as
second quality; or
o
hand painted and packed as first quality.
INSULATING MATERIAL
In Canada and the United States, there has been some
experience
using shredded waste paper as a thermal insulation material
(a
material that keeps warm houses warm and cool houses
cool. The
thermal efficiency (i.e., the effectiveness in preventing
movement
of heat) of the shredded and fluffed-up waste paper is
almost as good as glass fiber. To guard against fire, the
paper
is soaked in a solution of borax or alum, or other fire
retardant,
and then dried. Such material is much cheaper than other
thermal insulators and could be used widely where no straw
is
available, provided each batch is tested to ensure that the
fire-retarding
treatment is effective. It should be noted that rodents
like the salty treated waste paper for bedding and
penta-chlorphenol
Phenol is sometimes used against them. This is carcinogenic,
however,
and very hazardous to use.
FUEL
It is possible to pulp waste paper, compress it into
briquettes,
sun-dry these, and burn them as fuel. However, these
briquettes:
1. produce sooty
smoke, making them a poor choice for cooking or
use in the home;
2. burn poorly,
unless made as very small sticks; and
3. give out low
heat.
Only in the absence of any conventional fuel are they likely
to
be regarded as acceptable for domestic use. Industrial users
have
tried "refuse-derived" fuel pellets made from
municipal garbage
but these have not proved satisfactory. Undoubtedly, there
is a
Potential here but research and development are needed.
BIBLIOGRAPHY/SUGGESTED READING LIST
Ainsworth, J.H. "Paper the 5th Wonder," Thomas
Printing and Publishing
Company, 1959.
Appropriate Industrial Technology for Paper Products and
Small
Pulp Mills.
Vienna, Austria: United Nations Industrial
Development
Organization (UNIDO) , 1979.
Brook, S. "The Fine Art of Printing," Atlantic
Monthly, April,
1974 (112-115) .
Becker, W.J.
"The First Ten Years of the Fourdrinier,"
Paper
Trade Journal,
April 17, 1972 (34-41).
Becker, W.J.
"The First 145 Years of the Paper Machine in the
U.S.,"
Paper Trade Journal, May 27, 1972 (140-150).
Casey, James P.
"Papermaking," Pulp and Paper, Vol. II, New
York, New York:
Interscience Publishers, Inc., 1960.
Goodwin, Rutherford
"The William Parks Paper Mill at Williamsburg,
Virginia",
Lexington, Virginia: Bibliographical Society
of America,
1939.
Hunter, Dard Papermaking Pilgrimage to Japan, Korea, and
China,
New York, 1936.
Hunter, Dard Papermaking, New York, New York: Alfred A.
Knopf,
1967.
Hunter, Dard Papermaking in the Classroom, the Manual Arts
Press
Peoria,
Illinois.
Hunter, Dard "Watermarking Handmade Papers,"
Scientific American,
March 26, 1921.
Norris, F.H. Paper and Paper Making, New York, New York:
Oxford
University
Press, 1951.
Sarjeant, Peter T. Hand Papermaking Manual. Covington,
Virginia:
Paper Make,
1976.
Small-scale Paper-making, ILO Technical Memorandum No. 8.
Geneva,
Switzerland: International Labour Office, 1985.
Sweetman, J. "Making Paper by Hand," Appropriate
Technology,
Vol. 3, No. 4.
London: Intermediate Technoloqy Publications
Ltd.
Thomas, C. The Paper Chain. London: Earth Resources Research
Ltd., 1977.
Tsein, Tsuen-Hsuin
"China, the Birthplace of Paper, Printing and
Moveable
Type," Pulp and Paper International Journal, February,
1974.
von Hagen, V.W. The Aztec and Maya Papermakers, New York,
New
York: Hacker Art
Books, 1944.
Western, A.W. Small Scale Pulp and Paper Manufacture,
London:
Intermediate
Technology Publications Ltd., 1979.
EQUIPMENT SUPPLIERS
Paper
Mill Plant and
Machinery Manufacturers Ltd.
181 S V
Road
Jogeshwari, Bombay
400060
India
Hindon
Engineering Works
Clubley,
Bajoria Marg,
Saharanpur 247001
UP India
Indo
Berolina Industriea, Pvt. Ltd.
I.B.I.
House
5-86
Andheri Kurla Road
Bombay
400059
India
Jessop
and Co Ltd.
63 Netaji Subhas Road
P.O. Box
108
Calcutta, India
SOURCES OF INFORMATION
Association of the Pulp and Paper Industry
One Dunwoody Park
Atlanta, Georgia 30341
Write for free four-page booklet, "How You Can Make
Paper":
American Paper
Institute
260 Madison
Avenue
New York, NY
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