IMPROVEMENTS IN THE TREATMENT OF FIBROUS MATERIALS SUITABLE FOR THE MANUFACTURE OF PAPER
Year: 1870

page_text: PROVISIONAL SPECIFICATION left by Thomas Routledge at the Office
of the Commissioners of Patents, with his Petition, on the 14th
March 1870.
I, THOMAS ROUTLEDGE, of Ford Works, near Sunderland, Paper
Manufacturer, do hereby declare the nature of the said Invention for
"IMPROVEMENTS IN THE TREATMENT OF FIBROUS MATERIALS SUITABLE FOR THE
MANUFACTURE OF PAPER," to be as follows:-
This Invention relates to the preparation of wood or woody fibres
for the manufacture of paper stock and paper, part of which is also
applicable to the treatment of esparto, straw, and other fibres, and
also of rags which are to be employed in the manufacture of paper, and
consists,-
First. In subjecting wood or woody fibres to the action of an alkaline
ley at or below the ordinary atmospheric pressure.
Second. In the employment of a bowking arrangement of an improved
form in order to economize the quantity of alkaline solution usually
employed.

page_text: Third. In the employment of a system of washing or rinsing whereby
the alkaline ley remaining with an in the fibres or fibrous materials
after treatment with an alkaline ley is separated and is rendered available
either for the treatment of a fresh quantity of fibrous materials or for the
economical recovery of the soda therein.
Fourth. In the employment of spent or effete leys for the treatment
of the wood or woody fibres.
In carrying out the first part of my Invention it is essential that the
wood or woody fibres be first divided or reduced mechanically by any
convenient process into fine fibres, chips, shavings, or otherwise, which
should be as regular in form as possible. The disintegrated or com-
minuted fibres are then soaked, digested, or boiled in an alkaline ley
composed of soda by preference on account of its cheapness, the soda
being either in the carbonated or caustic state, the per-centage strength
of the soda in relation to the fibres being governed by the amount of
gum resin and extractive matters contained therein or combined there-
with. I place the finely divided wood or woody fibres in an open vessel
or boiler and boil or digest it in the alkaline solution sufficient to cover
it at or under atmospheric pressure, that is to say, at or under the boiling
point of the solution. The time required will vary from 6 to 12 hours
or more, depending upon the state of division of the fibre and the
nature of the material treated. If more convenient a closed vessel
rotating or otherwise may be employed, and steam at a pressure equal to
two or more atmospheres may be employed with a view to expedite the
process. I find that a temperature of 212° Fahrenheit, or the boiling
temperature of the solution, is sufficient to bring the gum resin and other
compounds combined with and in the wood or woody fibre into a soluble
condition so as to enable the soda ley to act upon and neutralize them,
and so set free-the extractive and coloring matters with the minimum
of waste, and also to bring the fibre into such a condition that after
being rinsed and washed it can be readily bleached and reduced into
paper stock or pulp fit for making into paper by itself or blended with
other materials, but I may remark that a larger quantity of bleaching
material is necessary than is usually employed. The strength of the ley
should be proportioned to the character of the wood or woody fibres,
some being stronger and containing more gum resin than others. For
woods of a soft nature the soda leys may be weak and used by preference

page_text: in the mild or carbonated form or condition, but for those of a stronger
nature or containing more resinous compounds the soda is preferably
used in the caustic condition and of a higher degree of strength. The
vessel or vessels in which the boiling or digesting process is conducted
may be of any convenient form, and it is desirable that circulation be
from time to time kept up. The vomitting or bowking keir used for
esparto, straw, and other paper-making materials may be employed, or
square or other convenient formed vessels heated from the bottom by
steam or by blind pipes with high pressure or superheated steam
circulating therein, or other convenient method, the system of heating
by blind pipes being preferable, as the normal strength of the ley is not
reduced. As it is, however, desirable to recover the soda employed, the
method I prefer is the digestion of the woody fibres in a soda ley of
from 6 to 15 times the strength that would be afforded by employing
a weak ley containing only from 6 to 15 per cent. of soda to the
fibre treated, and when the first charge is sufficiently operated upon or
cooked introducing further successive charges of fibre therein. As only
so much soda in each successive charge of digesting or boiling is
neutralized as combines with the gumming, resinous, and extractive
matters or compounds of the woody fibres, the remaining portion con-
tinuing free and active and ready to operate upon the further successive
charges until the leys are exhausted or neutralized and thus rendered
inoperative; or more soda may be added to the leys until they become
too heavily loaded with extractive matters for effective use. When this
point is reached the effete or spent leys are run down into pans or
otherwise, the water evaporated and the residuary mass incinerated to
recover the soda, which may be employed in future operations. It will
be obvious that by this system of boiling or digesting the original ley
necessary to immerse or cover the fibre can be used 6 or more times,
and the cost of evaporating the spent leys reduced pro tanto, the residuary
resinous mass as incinerated assisting as fuel.
In order (further) to carry on the process with the minimum of soda,
as also to reduce the quantity of water, which by the system now
practiced in the treatment of raw fibres for paper making is very great,
I prefer conducting both the boiling and washing processes in a series
of round or square vessels connected together by pipes in such manner
that by hydrostatic pressure when the boiling is finished and rinsing
commenced the clear water running into the top of the first of the series

page_text: which is connected by a pipe from under a false bottom to the upper
portion of the second of the series is forced or gravitated downwards and
then upwards successively and continuously through 8 or more pans
or vessels, by which system the clear or rinsing water will be used in
each of the 8 or more vessels consecutively until it becomes charged
with or takes up the soda left combined with the fibre in the pans after
boiling, and the resulting liquor will thus be concentrated and can then
be run off to be evaporated and the soda recovered, as with the spent
leys used for boiling,
This process is particularly suited for esparto grass, straw, or similar
raw fibres, and I find that after the rinse water has passed through eight
or more vessels it has become so charged with soda as to be as strong as
the original strong spent leys run off from the first boiling process.
For wood or woody fibre where strong leys are employed and successive
charges of fibre immersed therein I either pack the fibre in a perforated
cage which I suspend by chains or otherwise and let down each suc-
cessive charge into the vessel containing the ley, and when such charge
is done remove it to a series of washing vessels, as first described, or I
abstract by a pump the leys after a charge is boiled, introducing the leys
into another vessel over the fibres placed therein.
In order further to economise soda by increasing the density of the
leys, and at the same time reduce the cost of fuel for boiling or digesting
I attach to the bottom of an ordinary vomiting keir at and under
the centre of the false bottom a jug or vessel proportioned to the
size of the keir; for instance, for a kier capable of boiling one ton
of esparto the dimensions are about 8 feet 6 inches in diameter,
and 5 fect 6 inches deep, the interior diameter of, the puffing or
vomiting pipe being about 6 inches. In this case I make the jug or
vessel attached to the bottom of the keir 18 to 20 inches deep, and
from about 15 to 20 inches in diameter continuing the puffing pipe
furnished with the usual pipe which conveys the steam to induce the
vomit or continuous ascension of the leys to and over the esparto, woody
fibres, or other materials being treated therein. By this system the leys
may be used in a much more concentrated form and increased in strength,
whereby less soda is required and the cost for the evaporation of the
spent leys is also much economised, and the woody fibres or fibrous
materials being then treated by the system of rinsing or washing before
referred to,

page_text: I use the effete or spent leys after boiling esparto grass, straw, or
other materials used in paper making for boiling wood or woody fibre,
as I find the gum resin combined therewith materially assists the process;
and woody fibre thus treated comes up to a better color in bleaching,
besides which one evaporation of the spent leys is thus saved,