Method of Bleaching Paper Pulp or other Flocky Substances.
Year: 1894

page_text: Date of Application, 5th May, 1894--Accepted, 30th June, 1894
COMPLETE SPECIFICATION.
Method of Bleaching Paper Pulp or other Flocky Substances.
I, JOHAN WILHELM ÅBOM, Engineer, of Fredmansgatan No. 5, Stockholm,
Sweden, do hereby declare the nature of this invention and in what manner
the same is to be performed to be particularly described and ascertained in and
by the following statement :-
If, into a concentrated solution of some, one or more, of the chlorides of the
alkalic metals or the alkaline earthy metals an electric current (using carbon as
conducting plates) is conducted, the solution will be decomposed, so that some
chlorine is formed at the one pole and much hydrogen at the other and the solution
will besides contain a hypochlorite of the used metal.
The bleaching is performed so that paper pulp or other flocky substances are
introduced into a bleaching receptacle of wood or stone or, in general, of a non-
conducting material which is not influenced by the chlorine. The receptacle is
provided with a stirring device. The chloride solution is poured into the receptacle
in sufficient quantity, whereupon the electric current is let in to the pole plates and
the stirring device is put in action. The conducting plates are preferably arranged
so that one pole will be located at the circumference of the vessel and the other
pole at or near it centre. When the current has been in action during 20 to 40
minutes the contents of the receptacle are discharged into another suitable vessel,
where the after bleaching is carried on during 10 to 20 hours. New chloride
solution and material to be bleached are introduced into the receptacle, the stirring
device is put in action, current is let in and so on.
When the after bleaching has completely taken place, the solution used is
discharged, the bleached material is washed out with a little water which is added
to the solution together with a little of the chloride corresponding to the chloride
remaining in the goods, whereupon the solution is used over again.
During the bleaching operation the temperature must not from any cause be
allowed to rise to 608° C. as the hypochlorite will then easily be transformed to
chlorate, the chlorine of which is lost to the bleaching process.
On the accompanying drawing,
Figures 1 and 2 represent in vertical section and plan respectively a plant for
executing the above method.
In the vessel A provided with a stirring device a the bleaching material is
washed with the chloride solution whereupon the mass is led through the channel a¹
into the proper bleaching vessel B which is provided with the pole plates and ¹
which preferably consist of retort coke. The plates of the one pole are preferably
located at the wall of the vessel and the plates of the other pole in the middle of
the vessel so that the washed bleaching goods are forced by the paddle wheel B' to
pass between the pole plates. When the bleaching is completed the goods are let
down through the channel 62 into the vessel C in which the after bleaching takes
place. After the bleaching is performed and the bleaching goods have been
separated by means of a strainer the solution is pumped up into the vessel A in
order to be used over again. During the bleaching it is advantageous to reverse
the current now and then so that the pole plates which for the time have been
positive will be negative in order that both sets of plates may be evenly used.

page_text: Having now particularly described and ascertained the nature of my said inven-
tion and in what manner the same is to be performed I declare that what I
claim is:
In the bleaching of paper pulp and other flocky substances by electrolysis of the
chlorides of alkalic metals or alkaline earthy metals the method of exposing the
substances to be bleached to the simultaneous action of the ions which will act in
the nascent state.
Dated this 5th day of May 1901
JENSEN & SON,
77, Chancery Lane, London, W.C., 'Patent Agents.