Improvements relating to the Electrolysis of Salts and to Apparatus therefor.
Year: 1893

page_text: Improvements relating to the Electrolysis of Salts and to Apparatus
therefor.
I, THOMAS CRANEY, of 624 Harrison Street, in the City of Bay City, County
of Bay, and State of Michigan, United States of America, Manufacturer, 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 more specifically to that class of electrolytic apparatus
designed for the electrolysis of salts in solution.
My invention consists in a novel method, whereby the desired product of
electrolysis is obtained in a high state of concentration, and it further consists in
an apparatus for carrying out such method.
In the following description I will describe and show my invention as applied to
the manufacture of sodic hydrate from salt brine, and the apparatus which I have
devised for the purpose of carrying out my method is specifically designed for the
commercial manufacture of such sodic hydrate in concentrated form, so that the
product may be used commercially, as for instance in manufacturing soap.
In the accompanying drawings,
Fig. 1 shows a vertical, central section of one of the electrolytic cells of which
my apparatus is composed.
Fig. 2 shows my apparatus in elevation.
Fig. 3 is a plan view of Fig. 2.
My apparatus consists of a series of cells A each containing two communicating
compartments as shown in Fig. 1.
B representing the anode compartment, and B¹ the cathode compartment of the
cell, the two being formed preferably integral in one piece connected at the base
through a hollow trunk C.
The cell may be formed of stone or glassware or any other of the different
materials found suitable for the purpose.
Each of the chambers B B is preferably of cylindrical shape with an annular
flange D around the top into which fits the cover E, which cover is suitably
apertured to respectively receive an anode F and cathode G.
The anodes and cathodes may be of any known construction; in the drawings
the anode F consists of an open ended tube of glass or stoneware or other like
indestructible material, and is filled or packed with carbon with which the terminal
of the circuit is in electrical connection.
The lower end of this tube projects into a cup H, which is also filled with carbon
exposed on the surface to contact with the solution to be electrolized. The
cathode G to which the other terminal of the electric circuit is secured is shown as
consisting of a sheet of metal loosely rolled so as to prevent a large surface in
contact with the solution.
The two compartments B B₁ are covered at the bottom to a suitable height
above the trunk passage C, with an inert porous substance such as asbestos,
sand, etc., or preferably with a body of the solid substance to be electrolized, which
in the case of the decomposition of brine would be a body of common salt. Above
this to a certain height the compartments are filled with the salt brine.
Each compartment has inlet and outlet connections J, K, on opposite sides, and
the inlet connection J extends upwardly and the outlet connection K extends down-
wardly, and the two connections are adapted to form a joint when the cells are
arranged in a descending level as shown in Fig. 2 and 3.
compartments as shown in Fig. 1.
B representing the anode compartment, and B₁ the cathode compartment of the
cell, the two being formed preferably integral in one piece connected at the base
through a hollow trunk C.
The cell may be formed of stone or glassware or any other of the different
materials found suitable for the purpose.
Each of the chambers B B¹ is preferably of cylindrical shape with an annular
flange D around the top into which fits the cover E, which cover is suitably
apertured to respectively receive an anode F and cathode G.
The anodes and cathodes may be of any known construction; in the drawings
the anode F consists of an open ended tube of glass or stoneware or other like
indestructible material, and is filled or packed with carbon with which the terminal
of the circuit is in electrical connection.
The lower end of this tube projects into a cup H, which is also filled with carbon
exposed on the surface to contact with the solution to be electrolized. The
cathode G to which the other terminal of the electric circuit is secured is shown as
consisting of a sheet of metal loosely rolled so as to prevent a large surface in
contact with the solution.
The two compartments B B are covered at the bottom to a suitable height
above the trunk passage C, with an inert porous substance such as asbestos,
sand, etc., or preferably with a body of the solid substance to be electrolized, which
in the case of the decomposition of brine would be a body of common salt. Above
this to a certain height the compartments are filled with the salt brine..
Each compartment has inlet and outlet connections J, K, on opposite sides, and
the inlet connection J extends upwardly and the outlet connection K extends down-
wardly, and the two connections are adapted to form a joint when the cells are
arranged in a descending level as shown in Fig. 2 and 3.

page_text: As each succeeding cell in the series is placed upon a lower plane than the
preceding cell the level of the solution in the different cells is in like manner
maintained in different horizontal planes gradually descending from the first cell to
the last cell from which the product is discharged.
The solution of the salt to be decomposed is fed either in a continuous stream or
intermittently into the two compartments of the first cell, the drawing showing a
feed pipe L, from which valve-controlled supply pipes M M' pass into the com-
partments BB'. From there the solution overflows from one compartment into
the corresponding next one and so on through the series of cells, being discharged
from the compartments on the last cell into separate receptacles 0 0.
In the manufacture of sodic hydrate the common salt brine as taken from the
salt wells may be used, and this is decomposed by the electrolytic action of the
current which is made to pass through all the cells by means of suitable feeders PP'
arranged in multiple between the main conductors QQ of the generator. The
products, of decomposition is then sodic hydrate which is formed in the compart-
ments B accompanied by the formation of hydrogen gas, while chlorine gas is
evolved in the compartments B.
The chlorine gas in a measure will be carried off in solution with the overflow
into the receptacle O and may be recovered therefrom, if desired, for instance, by
heating the solution or it may be allowed to escape through suitable openings
formed in the cover of the compartments B.
The gaseous chlorine being heavier than atmospheric air will, if no other escape
is provided, flow from one cell into the next and escape at the discharge of the last
cell where it may be separately connected. The hydrogen gas may also be allowed
to escape from each compartment B' separately through suitable openings or pipes
or as it is lighter than atmospheric air it may be allowed to rise into the highest
compartment and from there allowed to escape.
In explaining my invention let us now suppose an ample flow of the liquid to be
electrolized to be taking place into the anode compartment of the first cell from
which it overflows into the corresponding compartment of the next cell, and so on
to the last cell, from which it is discharged.
This will maintain in the different anode compartments through the whole
series practically a saturated solution of the salt to be electrolized.
The supply of solution into the cathode side of the apparatus is regulated
according to the capacity of the apparatus to decompose most or all the salt by
the time it overflowed from the last compartment B1 of the series.
It will be seen that the amount of solution fed into the cathode side of the
apparatus is subjected to decomposition in each compartment and thus the quantity
of sodic hydrate will increase from cell to cell, but the gradual concentration of
the sodic hydrate will not arise only from this cause, but as the anode com-
partments contain practically a saturated solution of the salt maintained by an
abundant feed, the anode chambers will actively continue to transfer sodic hydrate
into the cathode chamber, and thereby constantly add to the quantity of sodic
hydrate.
By this accumulative method of electrolizing I have succeeded to obtain sodic
hydrate in any desired state of concentration by merely regulating the feed into
the cathode chamber. My method is altogether different from the ordinary process
of subjecting a certain quantity of a solution of salt to electrolysis, as even if the
decomposition of the salt shall be carried to its utmost possible limit (which is
practically too expensive) the product would not be concentrated, while with my
method can produce sodic hydrate having the consistency of syrup as regards
concentration.
The solution of salt of the cathode side need not be concentrated as even if
water alone would be introduced, the process would not be very materially
altered as the liquid is mainly necessary to discharge the sodic hydrate from the
apparatus. Up to a certain point however, the amount of sodic hydrate discharged
from the apparatus is increased by feeding a solution of the salt into the cathode

page_text: side of the apparatus, but if more is fed than can be decomposed the final product
of sodic hydrate would of course contain some of the undecomposed salt.
To obtain the product in a concentrated form it is necessary that the contents of
each cathode chamber should be as much separated as possible from any other
chamber, both for the purpose of preventing the reuniting of the different products
as well as to prevent the sodic hydrate in one compartment from mixing with that
in another compartment. The first object is obtained by separating the com-
partments in each cell by a porous diaphragm, and the second is obtained by means
of the different levels maintained by the solutions in the different cells.
The arrangement by which this is carried out is also of great importance as it is
about the only way in which a series of cells can be joined together. In my mode
the joint between two cells is never submerged by the liquid in the cell for if this
were the case it would be practically impossible to prevent leakage, as sodic
hydrate would attack and soon destroy any of the known cements that could be
used for a packing between the connections J and K.
With my construction there is no difficulty from leakage and if desired gas
tight joints may be readily made and maintained by the use of cement.
In the case of manufacturing sodic hydrate from common salt, the solution going
to waste on the anode side by overflowing is not of much account as it ordinarily
costs merely the price of pumping, but if desired, it can be freed from chlorine and
used again.
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 :-
:-
1. An electrolytic cell having separate anode and cathode compartments each
provided with a separate system of supply and discharge adapted to maintain the
liquid in the respective compartments in a uniform condition during continuous
operation, substantially as described.
2. An electrolytic apparatus composed of cells having separate anode and
cathode compartments in which the like compartments are connected in series,
and separate connections for supplying fresh liquid in regulated quantities into the
first compartment of each series and thereby producing a continuous flow through
all the compartments and a discharge from the last compartment of each series in a
manner to maintain each cell in a uniform condition of operation.
3. The herein described method of electrolizing salts in solution, the same
consisting in subjecting the solution to electrolytic action in a cell having separate
anode and cathode compartments, in supplying the anode compartment with fresh
solution in quantity to maintain it in concentration, and in removing the product
from the cathode compartment by a regulated supply of fresh liquid, substantially
as described.
Dated: 01.4
1000
THOMAS CRANEY.
Haseltine, Lake & Co.,
45, Southampton Buildings, London, Agents for the Applicant.