Improvements in the Purification of Saccharine Juices by Electro- lytic Treatment, and Means employed for that Purpose.
Year: 1895

page_text: Date of Application, 6th Apr., 1895-Accepted, 6th July, 1895
[Communicated from abroad by LA SOCIÉTÉ ANONYME RAFFINERIE SAY, of
Paris, France.]
Improvements in the Purification of Saccharine Juices by Electro-
lytic Treatment, and Means employed for that Purpose.
I, OLIVER IMRAY, of No. 28 Southampton Buildings, Chancery Lane, in
the County of London, Chartered Patent Agent, do hereby declare the nature of
this invention and in what manner the same is to be performed to be particulafly
described and ascertained in and by the following statement :-
For some time past my foreign correspondents have made use of metallic alloys
for forming the anodes serving for the electrolytic treatment of cane juice, and
they have found advantages in such use relatively to certain deposits which tend to
form on the anodes and thus interfere with the electrical action.
There are however some saccharine juices which, notwithstanding the use of
these anodes, resist a complete purification in consequence of an adhesive deposit
therefrom which forms on the surface of the anodes.
A careful examination has shown that the principal constituent of these deposits
is an oxide of lead which a certain number of weak organic acids contained in
the saccharine juices cannot saturate, in consequence of which the electrolytic
action is incomplete.
The salts formed by these weak acids are no doubt decomposed, but in consequence
either of these acids being insoluble, or of their affinity for the oxide of lead being
too feeble, the combination is not produced. From this a twofold inconvenience
arises, namely, on the one hand the acidification and consequently alteration of
the saccharine juices, and on the other hand the oxide of lead more or less mixed
with other substances, forms on the surface of the anodes a kind of insulating
coating which obstructs the passage of the electric current.
According to the present invention these difficulties are obviated by the
combination of a chemical and a mechanical treatment, each of which can
sometimes be used separately but which it is preferred always to employ
simultaneously.
For this purpose there is added to the saccharine juice a certain dose (which
may be from th to 1 of the weight of the ashes of the saccharine matter) of a
salt such as chloride of sodium or of an energetic acid that will combine readily
with the lead for forming an insoluble salt, or one that is only slightly soluble.
This salt being decomposed by the electrolytic action in proportion as the
purification proceeds, gives hydrochloric acid which, in constantly attacking the
metal, maintains the lead plate of the anode in a perfectly clean or uncoated
condition, thus allowing the plumbic combinations to take place which could not
occur without this precaution.
Furthermore, in consequence of this small degree of affinity, it is essential to
cause all parts of the anode to be in intimate contact with all parts of the
saccharine juice.
In order to obtain this result, instead of employing an anode of flat form, it is,
according to this invention, made of a pleated or corrugated form in vertical section,
forming sinuosities or corrugations which occupy nearly the whole of the width of
the compartment of the saccharine juice.
This anode can receive, by means of an excentric, a reciprocating vertical motion
corresponding to the length of an undulation. Under these conditions it will be

page_text: This
seen that not only will the lead be brought in contact with all the saccharine
molecules in the width of the compartiment, but the movements caused in the liquid
mass will produce an agitation which will multiply the points of contact.
arrangement is consequently of considerable importance, both in theory and in
practice. It satisfies the theoretical condition of diminishing as much as possible
the thickness of the layer of liquid subjected to electrolysis, and in practice, it
enables apparatus to be constructed with large compartments which diminishes
the first cost of installation, and facilitates the progress of the operation, while
preventing a too rapid and too compact deposit of the lead sludge.
Having now particularly described and ascertained the nature of this inven-
tion and in what manner the same is to be performed, I declare that what I
claim is :-
--
1. In the purification of saccharine juices by electrolytic treatment, the use of
a soluble salt produced by an energetic acid which will form with lead insoluble or
only slightly soluble salts, such first named salt being added to the saccharine
juice in such manner that by its progressive decomposition during the electrolytic
operation, it maintains the anode in a clean or uncoated condition so as to allow
of the completion of the purification of the whole of the saccharine juices,
substantially as described.
2. In the purification of saccharine juices by electrolysis, the use of anodes of
a sinuous, pleated or corrugated form, having a reciprocating motion imparted
thereto, so as to produce an intimate and continuously repeated contact of the
lead anode with the saccharine liquid in which it is immersed, substantially as
described.
3. In the purification of saccharine juices by electrolysis, the combined use of
the soluble salt referred to in the first claim and of the construction of anode
referred to in the second claim, substantially as described.
Dated this 6th day of April 1895.
ABEL & IMRAY,
Agents for the Applicant.