Improvements in the Electrolytical Manufacture of Bleaching Liquid.
Year: 1895

page_text: Date of Application, 19th Sept., 1895
Complete Specification Left, 19th June, 1896-Accepted, 15th Aug., 1896
PROVISIONAL SPECIFICATION.
Improvements in the Electrolytical Manufacture of Bleaching
Liquid.
I, CARL KELLNER, of No. 29 Wasagasse, Vienna IX, Austria, Doctor of
Philosophy, do hereby declare the nature of this invention to be as follows:-
This
This invention relates to a method of electrolytically manufacturing bleaching
liquid having a high percentage of active chlorine, whereby the re-use of the
solution of the electrolyte, which is troublesome, is rendered unnecessary.
method consists in repeatedly passing the electrolyte rapidly through the decom-
posing cells, and continuously abstracting, by means of cooling apparatus, the heat
produced by the work of the current and by the reactions.
It has before been proposed to provide the electrolytic cells of electrolytic
apparatus with cooling apparatus, but these cooling apparatus have been too
complicated for industrial purposes, whilst even with their use hypochlorite
solutions having a high percentage of chlorine cannot be produced. Now, by
means of the method constituting the present invention, bleaching liquid having a
high percentage of active chlorine or active chlorine compounds can be produced
with any desired decomposing apparatus. According to my invention the decom-
position is effected only up to a slight degree (about 0.05% of chlorine) during
each passage of the electrolyte through the apparatus; the electrolyte is then
cooled, afterwards passed a second time through the decomposing cell, and then
again cooled; and this succession of decomposing and cooling operations is con-
tinued until the desired concentration (say about 1.5% of chlorine = 15 grammes
per litre) is attained.
=
As an 8 to 10% solution of chloride of sodium is suitable for this purpose, and,
in most bleaching processes 3% of active chlorine is sufficient to bleach the
material to be bleached, there are, for instance, required, for bleaching 100 kilogs.
200 litres
of raw material, 3000 grammes of chlorine 15 grammes of chlorine
= 20% salt.
of an 8 to 10% solution of NaCl-that is to say 200: 80 = 16 kilogs.
Consequently the electrolytic bleaching liquid prepared in this manner-such as
a solution of chloride of lime-can be charged into the pulp or stuff engines
bleaching vats etc., and then be run off with the washing-water, instead of
recovering it by means of washing-drums, pulp or stuff presses or other water-
removing apparatus, as has been necessary heretofore in all electrolytic processes.
It has been proved by experiment that the useful work done by the current does
not sink to any great extent below that determined theoretically by calculation.
Thus this simple arrangement enables a very important technical result to be
effected.
The accompanying illustrative drawing represents, by way of example, an
apparatus for carrying out this process.
A is a reservoir containing an 8 to 10% solution of electrolyte (preferably
sodium chloride). By means of a pump P and a pipe 5 this solution is passed in a
constant stream through the decomposing-cell Z, becoming thereby partly enriched
with chlorine. The solution flows through a pipe 1 back into the reservoir A, in
wbich there is situated a cooling apparatus K of any suitable construction. This
circulation of the electrolyte is continued until the solution shows the desired

page_text: percentage of free chlorine, whereupon the pipe 1 is closed, and the contents of the
reservoir A are discharged through the cell Z and the pipe 2 into a receptacle B,
to be utilized in a similar mauner to a solution of chloride of lime. It is to be
understood that the operation of the apparatus may be arranged to be continuous,
by allowing fresh electrolyte to flow constantly from a receptacle C (indicated in
dotted lines) and through a pipe 3 into the suction pipe of the pump, and by
causing a corresponding quantity of strong solution to flow from the pipe 1 through
a pipe 4 (indicated by dotted lines) into the storage vessel B.
Dated this 19th day of September 1895.
F. WISE HOWORTH,
46, Lincoln's Inn Fields, London, W.C., Agent for the Applicant.
Improvements in the Electrolytical Manufacture of Bleaching
Liquid.
I, CARL KELLNER, of No. 29, Wasagasse, Vienna IX, Austria, Doctor of
Philosophy, 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 :-
This invention relates to a method of electrolytically manufacturing bleaching-
liquid having a high percentage of active chlorine, whereby the repeated use of
one and the sanie electrolyte solution for the bleaching process, which is trouble-
some, is rendered unnecessary.
The method consists in repeatedly and rapidly passing the electrolyte through
the decomposing cells, and continuously abstracting, by means of cooling apparatus,
the heat produced by the work of the current and by the reactions that take place
during the process.
It has heretofore been proposed to provide the electrolytic cells of electrolytic
apparatus with cooling apparatus, but these cooling apparatus have been too
complicated for industrial purposes, whilst even with their use hypochlorite
solutions having a high percentage of chlorine cannot be produced. Now, by
means of the method constituting the present invention, bleaching liquid having a
high percentage of active chlorine or active chlorine compounds can be produced
with any desired decomposing apparatus. According to my invention the decom-
position is effected only up to a slight degree (about 0.05% of chlorine) during
each passage of the electrolyte through the apparatus; the electrolyte is then
cooled, afterwards passed a second time through the decomposing cell, and then
again cooled, this succession of decomposing and cooling operations being con-
tinued until the desired concentration (say, about 1.5 % of chlorine = 15 grammes
per litre) is attained.
As an 8 to 10% solution of chloride of sodium is suitable for this purpose, and,
in most bleaching processes, 3% of active chlorine is sufficient to bleach the
material to be treated there are, required for bleaching for instance 100 kilogs. of
raw material, 3000 ÷ 15 = 200 litres of an 8 to 10% solution of NaCl-that is to
say, from 16 to 20% of salt.
Consequently the electrolytic bleaching liquid prepared in the manner described―
such for example as a solution of chloride of lime-can be charged into the pulp or
stuff engines bleaching vats, etc., and then be run off with the washing-water,
instead of recovering it by means of washing-drums, pulp or stuff presses, or other
water-removing apparatus, as has heretofore been necessary in all electrolytic
bleaching processes.
It has been proved by experiment that in carrying out my invention the useful

page_text: work done by the current does not fall to any great extent below that determined
theoretically by calculation.
Thus the simple method hereinbefore described enables a very important
technical result to be obtained.
The drawing filed with my Provisional Specification represents by way of
example, an apparatus for carrying out my invention.
A is a reservoir containing say an 8 to 10% solution of electrolyte (preferably
sodium chloride). By means of a pump P and a pipe 5 this solution is passed
in a constant stream through the decomposing cell Z and thereby becoming partly
enriched with free chlorine. The solution flows through a pipe 1 back into the
reservoir A, in which there is situated a cooling apparatus K of any suitable
construction. This circulation of the electrolyte is continued until the solution
shows the desired percentage of free chlorine, whereupon the pipe 1 is closed, and
the contents of the reservoir A are discharged through the cell Z and the pipe 2
into a receptacle B, to be utilized in a similar manner to a solution of chloride of
lime. The operation of the apparatus may be arranged to be continuous, by
allowing fresh electrolyte to flow constantly from a receptacle C (indicated in
dotted lines) and through a pipe 3 into the suction-pipe of the pump and allowing
a corresponding quantity of strong solution to flow from the pipe
past a valve
and through a pipe 4 (iudicated by dotted lines) into the storage-vessel B.
Having now particularly described and ascertained the nature of the said inven-
tion and in what manner the same is to be performed I declare that what 1
claim is :-
1. The herein described method for electrolytically producing a highly con-
centrated bleaching liquid by passing the electrolyte rapidly through a decomposing
cell in such a manner that it becomes enriched only to a slight extent with active
chlorine or active chlorine compounds, then cooling the same, again passing it
through the decomposing cell, and repeating this partial electrolysis and cooling
alternately until the desired percentage of active chlorine or active chlorine
compounds has been obtained, substantially as described.
2. The modification of the method specified in the preceding claim according to
which fresh electrolyte is supplied to the electrolyte circulating between the
cooling apparatus K and the decomposing cell Z, in the same proportion as
bleaching liquid of high percentage is drawn off from the decomposing cell,
substantially as herein before described.
Dated this 18th day of June 1896.
F. WISE HOWORTH,
46, Lincoln's Inn Fields, London,, W.C., Agent for the Applicant.