IMPROVEMENTS IN THE TREATMENT OF BARK AND SPENT BARK FOR, THE MANUFACTURE OF PAPER AND PAPER BOARD AND IN APPARATUS, TO BE USED. THEREIN, PARTS OF WHICH PROVISIONAL SPECIFICATION
Year: 1882

page_text: LETTERS PATENT to William Moore Riddell of Finsbury Pavement in the City
of London, Civil Engineer, for an Invention of "IMPROVEMENTS IN THE
TREATMENT OF BARK AND SPENT BARK FOR, THE MANUFACTURE OF PAPER AND
PAPER BOARD AND IN APPARATUS, TO BE USED. THEREIN, PARTS OF WHICH
PROVISIONAL SPECIFICATION left by the said William Moore Riddell at
the Office of the Commissioners of Patents on the 19th September 1882.
WILLIAM MOORE RIDDELL of Finsbury Pavement in the City of London, Civil
Engineer "IMPROVEMENTS IN THE TREATMENT OF BARK AND SPENT BARK FOR THE
MANUFACTURE OF PAPER AND PAPER BOARD AND IN APPARATUS TO BE USED THEREIN
PARTS OF WHICH IMPROVEMENTS ARE APPLICABLE TO OTHER PURPOSES."
"
In treating bark or spent bark according to my invention in order to obtain a
fibre suitable for the manufacture of paper and paper boards I proceed as
follows:-
I place the bark or spent bark to be treated in a tank or vessel of suitable size
and shape provided with a steam-tight cover and a perforated false bottom or grid
on which the bark or spent bark rests. This vessel is throughout made of, or lined
with, some material which will not act injuriously on the tannic acid contained in
the bark. This vessel I connect by suitable pipes with a steam generator from
which dry steam is supplied to the upper part of the vessel and is caused to
percolate or filter through the mass of bark, cleansing it from all impurities and
extracting the tannic acid which it contains. The lower part of the vessel below
the false bottom is connected by suitable pipes with a receiver also made of a
material which will not affect or be affected by the acid, injuriously.
Suitable stop-cocks are provided, both for the admission and outlet pipes, and
these are so adjusted that the dry steam is supplied under some pressure, thus
ensuring the speedy and complete expulsion of the impurities such as the resin,
wax, and albuminous matters which pass away with the tannic acid as fast as the
steam is condensed.

page_text: When the pale colour of the extract indicates that the bark or spent bark has
been sufficiently subjected to the action of dry steam, and thoroughly deprived of
its tannic acid and other impurities, it is removed while still hot to a beating or
breaking engine enclosed in a case in connection with a steam generator, and is
therein subjected to the tearing or separating action of a series of iron spikes or
wire brushes in the presence of steam, until thoroughly torn into fibres.
This tearing engine enclosed in a case and supplied with steam as above described
may also be used with advantage in preparing straw and Esparto grass and similar
fibres for the manufacture of paper, as by rendering all parts of the straw or grass
equally tender, it ensures a uniform separation of the fibres.
It is important in carrying out. the above process that the vessel in which the
bark is subjected to the softening and cleansing action of the dry steam constantly
percolating or filtering through it, should not be made of such a metal, for example,
as iron, which would re-act on the tannic acid and cause the formation of tannate
of iron which would not only render the tannic acid valueless, but would leave the
fibres hard and tough and unsuited for the end in view, and for this reason I
preferably use a wooden or leaden vessel.
It is also important that no moisture should be added to the bark or spent bark
in the vessel beyond what results from the condensation of the steam, and that the
bark should be conveyed to the tearing engine while still hot and be kept hot by
contact with steam during the tearing operation.
The spikes or stiff metallic brushes of the tearing engine work over a bed plate
of corrugated metal, or over knives, spikes or brushes.
The fibrous mass after it leaves the tearing engine is washed by means of a
washing drum which is lowered into the tank in the usual manner, and it is then
ready for use in the manufacture of paper and paper board.

page_text: fibre suitable for the manufacture of paper, paper boards and other useful purposes.
In order that the Invention may be well understood and explained in detail I
have hereunto annexed a Sheet of Drawings on which letters of reference are
marked on corresponding parts on all the Figures alike.
DESCRIPTION OF DRAWINGS
Fig. 1. represents a vertical section of the chamber, tank or receptacle in which
the bark to be treated is first placed for being cleansed and softened.
Fig 2, represents a plan view of the second chamber tank or receptacle (with its
steam tight cover removed) in which the bark after its removal from the first
vessel is placed for final treatment preparatory to its being converted into pulp, and,
Fig 3. represents in vertical section half of the teasing or tearing roller enclosed.
in the second steam tight vessel together with the corrugated bed or plate between
which and the teeth of the said roller the fibrous bark is passed.
In these Figs a is the first chamber tank or vessel in which the bark or spent
bark to be treated is placed, this vessel a is provided with a steam tight cover a¹.
and safety valve a³, a false perforated bottom or grid b is fixed in this vessel upon
which the bark rests. The vessel a is throughout made of or lined with some
material which will not act injuriously on the tannic acid contained in the bark
preferably of wood or lead because if iron were used it would cause the formation
of tannate of iron which would not only render the tannic acid valueless, but
would leave the fibre hard and tough, and unsuited for the end in view. The
upper portion of the vessel a I connect by the pipe 6' with a steam generator, and
the pipe 6 with a hot water cistern or boiler, both pipes being provided with the
stop cocks or taps c. and c'. The steam pipe b¹. I extend so as to allow it to enter
the lower portion e, of the vessel or tank a below the false perforated bottom b,
thereof, the said extended length of the steam pipe 6' I also provide with a stop
cock or tap c², and the space e of the tank a I also provide with an outlet pipe and
stop cock or tap c³.
When the tank or vessel a has been filled with bark or spent bark the lid or
cover a¹ is lowered and secured down by the bolts f f. so as to make a steam tight
joint on the seating of the tank a When the cover a¹ is so secured down the
stop cocks or taps c and c³ only are opened which allows high pressure steam to be
admitted to the upper portion of the tank a which percolates or passes through the
mass of bark contained in the tank which cleanses. it from all impurities and
extracts therefrom the tannic acid which it contains.-The impurities as extracted
pass away with the condensed steam through the perforated false bottom b, into
and out of the space e, through the exit pipe c³. The dry steam so admitted under
pressure ensures the speedy expulsion of impurities such as resin wax and other.
extraneous matter contained in the bark which pass away through the exit pipe c³.

page_text: -
but in order more thoroughly to cleanse, soften and prepare the bark for its final
treatment in the second chamber or receptacle hereinafter described I further
subject the bark or spent bark to a process of boiling under pressure as follows:-
I close the steam cock c and exit cock c³ and then open the cocks c³ and c¹ the
former of which admits steam to the lower receptacle e below and through the
perforations of the false bottom b. and the latter admits hot water to the upper
space of the tank a above the bark.-Immediately the steam and hot water
are thus admitted the Steam ascends through the mass of bark and so causes the
water to boil under pressure, the limit of such pressure being governed by the
safety valve a².
.
When the pale color of the extract indicates that the bark or spent bark (by
testing at the tap or cock c³) has been sufficiently subjected to the steaming and
boiling process, and thoroughly deprived of its, tannic acid and other impurities
the lid or cover a' is removed so as to expose the bark in the tank a which is then
tilted or turned on its central supports g. g into a position which will allow of the
easy removal of the cleansed hot bark from the said tank into the second chamber
or receptacle h (see Fig 2). This chamber h contains a breaking Engine provided
with a roller i containing around its periphery a number of iron spikes or stiff
wire brushes.
When the hot or spent bark has been placed in the chamber or receptacle h. the
whole is closed in by a Steam tight cover and steam is admitted thereto through
the pipe k, and hot water by the pipe The tearing or breaking roller i driven
by the pulley m is then caused rapidly to revolve. The lower surface or bed
plate o. of the chamber h immediately under the iron teeth, spikes, or stiff metallic
brushes of the roller i (as seen at Fig 3) is corrugated or formed of knives, spikes,
or brushes, so that when the roller i is rapidly revolving it first decorticates and
disintegrates the outer skin or rind of the hot bark submitted to its action which
is carried off by the washing action of the hot water which circulates and passes.
out from the steam chamber through the interior of the washing drum n by the
exit pipe p.
Or in lieu of the roller i Edge-runners may be employed for tearing
and separating the fibres whilst in the steam tank h.
The continued rapid action of the breaking or tearing roller i or Edge runners
in the presence of Steam tears and converts the remaining interior portion of the
bark into a fine fibrous condition. This fibrous mass after being washed in the
same vessel by means of a washing drum lowered therein in the usual manner is
ready for use for being manufactured into paper or paper boards.
The tearing roller i or edge runners enclosed in a tank or chamber and supplied
.with steam and water in manner as herein described may also be used with
advantage in the preparation of Straw, Esparto Grass and similar fibres for the
manufacture of paper as by rendering all parts of the Straw or Grass equally tender
it insures a uniform separation of the fibres.
It is important that no moisture should, be added to the bark or spent bark in
the tank a beyond what results from the condensation of Steam until the tannic
acid is removed, and before the entrance of Steam and Water for boiling under
pressure is commenced, and it is further important that the bark. when the process
is completed in the first tank a should be conveyed to the second tank h whilst still
hot, and be kept hot by contact with steam as described during the tearing
process.
Having now described the nature of my said Invention together with the means
I employ for carrying the same into practical effect I wish it to be understood in
conclusion that what I claim as new and as of my Invention is
First treating or subjecting bark or spent bark when enclosed in the tank a in
the Drawings annexed to the process. of Steaming and washing for cleansing and
softening in the manner as herein substantially described set forth and illustrated
in the Drawings annexed-and,
J
Secondly subjecting such bark or spent bark after it has undergone the

page_text: cleansing and softening process to the action of the tearing roller i contained in a
steam tight closed tank h in the manner and for the purpose as herein substantially
described set forth and illustrated in the Drawings annexed.
In witness whereof I the said William Moore Riddell have hereunto set my
hand and seal this the nineteenth day of March in the year of our Lord,
One thousand eight hundred and eighty three.
Witness :-
THOMAS WRIGLEY.
75 Chancery Lane W.C
WILLIAM MOORE RIDDELL (L.S.)