IMPROVEMENTS IN THE PREPARATION OF MATERIALS FOR THE MANUFACTURE OF PAPER, AND APPARATUS THEREFOR
Year: 1874

page_text: PROVISIONAL SPECIFICATION loft by Edward Alfred Cowper at the
Office of the Commissioners of Patents, with his Petition, on the
27th October 1874.
I, EDWARD ALFRED COWPER, of No. 6, Great George Street,
Westminster, in the County of Middlesex, do hereby declare the nature
of the said Invention for "IMPROVEMENTS IN THE PREPARATION OF MATERIALS
FOR THE MANUFACTURE OF PAPER, AND APPARATUS THEREFOR," to be as
follows:-
My Invention relates to an improved process and apparatus for the
preparation of materials for the manufacture of paper, more particularly
applicable to the treatment of vegetable substances, such as bamboo,
having a siliceous coating.
I boil the material in a solution of caustic alkali (preferably soda) in
a vomiting pan or other vessel in which a rapid circulation is maintained
by steam or heat, and when the alkali has become somewhat neutralised
or spent I either while it is still hot run off the liquid into another
vessel and boil it with lime so as to render the alkali again caustic, or I
remove the charge of vegetable matter from the pan and introduce lime

page_text: to recausticise the alkali, the liquid being thus rendered again capable of
acting on the vegetable matter.
The material may be first boiled in weak caustic or in the black liquor
or spent lye of previous boilings which has been recausticised as described
above, and when the liquor has become weakened or spent it is again
causticised and used several successive times. When the material has
been' thus sufficiently treated it is boiled in clear caustic alkaline
solution and finally in water to remove such colouring matter as may
have remained in it after the previous boilings. Before the final boiling
in caustic and water, the material may be passed between rolls to express
the colouring matter with the black liquor more thoroughly. The
vegetable material is more readily acted on as described above, if it has
in the first place been passed between rollers or subjected to the action
of stampers or hammers, as the liquor can thus be made to penetrate it
more freely; and in the case of bamboos and other materials having knots,
it is preferable to remove the knots in the first place.
As in the manufacture of silicate of soda it has been found that a high
temperature and a considerable pressure are required to quickly dissolve
silica in a solution of caustic soda, so when fibrous materials containing
silica arc treated at moderate temperature as above described, only a
very small portion of the alkali is absorbed by the silica, the greater part
remaining useful for disintegrating action upon the fibres, the silica
being in great measure disengaged in the form of uncombined silica or
sand.
The process set forth above may be carried on in one or more boilers,
the material being allowed to remain in the boiler and the liquor run out
to be causticised being replaced by liquor which has been causticised, or
the material may be moved from one boiler to another after each
operation.
When the spent liquor is removed from the boiler for the purpose of
being recausticised, I prefer to arrange the boilers and causticising
vessels in such a manner that the liquor can be readily run or caused to
flow from the one to the other by gravity or by pumps, injectors, or other
convenient means.