A Process of and Apparatus for Electrically Decomposing Solid Substances.
Year: 1897

page_text: Date of Application, 7th May, 1897
Complete Specification Left, 7th Mar., 1898-Accepted, 9th Apr., 1898
PROVISIONAL SPECIFICATION.
A Process of and Apparatus for Electrically Decomposing Solid
Substances.
I, WILLIAM SWART ROMME, Gentleman, a Citizen of the United States of
America, residing at 15, Hanford Avenue, in the City of New Rochelle, and
State of New York, United States of America, do hereby declare the nature of this
invention to be as follows:-
My invention relates to a process of electrically decomposing solid substances,
and to an apparatus for carrying out the process. The process is particularly
intended by me for the decomposition of salts of alkalies, such as the chlorides of
sodium and potassium, and the production of hydrates or hydroxides and chlorine
therefrom, but it is equally applicable to the treatment of other salts and compounds
which it is possible to decompose electrically. My invention consists in causing
water or other suitable fluid, a solvent of the substance treated, to percolate through
the mass treated while the decomposition is going on, the fluid being used in
such quantity as suffices merely to keep the mass moist without submerging it in
the fluid; and my invention consists also in the apparatus used for carrying out the
process.
The objects of my invention are, first, to provide a process of electrically
decomposing solid substances, such as those mentioned above, which shall require
less expenditure of energy than former processes and shall avoid waste of current
through the unnecessary decomposition of the water or other fluid surrounding
the substance treated; second, to provide a process which shall avoid the clogging
of the fluid surrounding the substance treated with the soluble products of
decomposition, which shall permit the withdrawal of these soluble products of
decomposition in a practically pure state while the process is going on, and which
may be carried out by the aid of simple apparatus and shall be comparatively
inexpensive; and third, to provide a simple, effective, and comparatively
inexpensive apparatus for carrying out this process.
My process is conducted in a suitable tank or vessel provided with electrodes
which are preferably horizontal and are placed one above the other, the lower
electrode being provided with perforations through which the soluble products
of decor position may flow off. The substance to be decomposed is placed between
the electrodes in a solid state. It is then moistened with water or other solvent
of the substance treated to permit the ready passage of an electric current and the
action of the current on the substance, and an electric current is passed through
the mass. During the time the electric current is passing I cause a stream of
water, or other solvent, to percolate through the mass undergoing treatment, which
keeps it moist and in a condition to be acted upon by the electric
current, and insures a uniform action upon the substance treated, and
in flowing away carries with it the soluble products of decomposition. Only
enough water used to keep the mass undergoing treatment moist throughout
without submerging it, and I avoid the use of water in such quantity that the

page_text: water itself is decomposed to any considerable extent, as work done in decomposing
the water is wasted. By using merely enough water to keep the mass under
treatment moist I avoid the decomposition of the water itself, and do not require
an electric current of as great potential as has been required by former systems of
electrical decomposition in which the substance treated is first dissolved and the
solution treated, or in which there is a large quantity of free water present between
the electrodes. In such systems an otherwise unnecessarily high current potential
is required in order to prevent the chlorine from combining with the water. As
my system of decomposition is conducted, there is practically no free water
between the electrodes, the mass of salt or other substance being merely moist,
and what water is present is saturated with the substance under treatment, and
does not absorb chlorine which may be liberated at the upper electrode. I also
avoid all of the trouble and inconveniences to which systems of electrical
decomposition in which the substance to be treated is first fused are necessarily
subject.
In the decompositon of many substances, such for instance as potassium and
sodium chloride, one product of the decomposition is a gas, which, if collected,
may be utilized to advantage. For this reason the tank may be provided with a
cover which may be closed and which will prevent the escape of gas. In order to
draw off the gaseous products of decomposition a pipe may be provided which may
if necessary be connected to an exhaust pump. Instead of drawing off the gas
it may be absorbed in an absorbent material, such as lime, within the tank.
The manner of carrying out the process may be illustrated by describing the
production of chlorine and sodium hydrate or hydroxide from sodium chloride,
i.e. common salt. The salt, in granular or crystaline form, is placed between the
electrodes and is moistened with water. The water dissolves a portion of the
salt, and holds it in solution in condition to be acted upon by the electric current.
When the mass is moist throughout the electric current is turned on and passes
from the one electrode to the other. In passing through the mass of salt the
electric current decomposes the salt in solution into its elements, viz., metallic
sodium and chlorine gas. The chlorine gas rises and may be drawn off through
a suitable pipe, and may be utilized in various ways, as for instance, in the
production of bleaching powder. It may also be absorbed by an absorbent
material, as lime, in the tank. The metallic sodium liberated immediately com-
bines with the water to form caustic soda, or sodium hydrate or hydroxide, as it is
more properly termed. The caustic soda is carried by the water through the
perforations in the lower electrode and may be collected in any suitable manner.
Water is constantly supplied, but in such quantity only as suffices merely to keep
the mass moist, to take the place of the water which combines with the sodium
and flows off through the perforations in the lower electrode. If the quantity of
water used be properly regulated the fluid which flows through the perforations in
the lower electrode will be a strong solution of caustic soda, containing little or
no sodium chloride.
As the decomposition goes on the products of the decomposition are carried away
immediately. In former processes of decomposition, where the salt has first been
dissolved, the caustic soda is left in the solution when formed and so clogs the
solution. Moreover as the process proceeds the salt solution becomes weaker, and
it is impracticable to utilize all of the salt in the solution. Moreover a good deal
of the current is wasted in decomposing the water itself, and a current of
greater potential is required than by my process, since the resistance
of the solution is much greater than the resistance of the moistened mass
of salt between the electrodes of an apparatus used for carrying out my
process, and since in former processes a higher potential than would otherwise be
needed is required to prevent, so far as possible, the chlorine from dissolving in
the water. In my process the chlorine is liberated above the greater part of the
mass of salt, and moreover what water there is in the mass is saturated with salt,
and does not dissolve the chlorine. Also, when the water itself is decomposed

page_text: some ozone is generated and attacks the positive electrodes, soon destroying them.
All of these objections are avoided in the process above described. The treatment
of the salt in a solid state instead of dissolving it before placing it in the apparatus,
has the further advantage that the apparatus may be much smaller than when
Bolutions are used.
Sodium carbonate, when treated in a similar manner, is decomposed into carbonic
acid gas and sodium oxide. The sodium oxide when formed is immediately
converted into the hydrated oxide or hydroxide, and passes off as before.
Salts of substance similar to the sodium salts, such as, for instance, the potassium
salts, may be treated in the same manner with corresponding reactions.
Instead of introducing water as a liquid, I may introduce it as steam, which
will immediately become liquid in the tank. Steam, however, penetrates the mass
undergoing treatment more readily than a liquid.
EDWARDS AND Co.,
65 and 66, Chancery Lane, London, Agents for the Applicants.
A Process of and Apparatus for Electrically Decomposing Solid
Substances.
I, WILLIAM SWART ROMME, Gentleman, a Citizen of the United States of
America, residing at 15, Hanford Avenue, in the City of New Rochelle, and
State of New York, United States of America, 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, and accompanying
drawing, that is to say:
-
My invention relates to a process of electrically decomposing solid substances,
and to an apparatus for carrying out the process. The process is particularly
intended by me for the decomposition of salts of alkalies, such as the chlorides of
sodium and potassium, and the production of hydrates or hydroxides and chlorine
therefrom, but is equally applicable to the treatment of other salts and compounds
which it is possible to decompose electrically. My invention consists in causing
water or other suitable fluid, a solvent of the substance treated, to percolate through
the mass treated while the decomposition is going on, the fluid being used in
such quantity as suffices merely to keep the mass moist without submerging it in
the fluid; and my invention consists also in the apparatus used for carrying out the
process.
The objects of my invention are, first, to provide a process of electrical decom-
position of substances, such as those above mentioned, which shall require a
comparatively small expenditure of electric current and shall avoid waste of
current through the unnecessary decomposition of the water or other fluid solvent
of the substance treated; second, to provide a process of electrical decomposition
by which the substance to be decomposed may be placed in the decomposition
chamber and between the electrodes in a solid condition, thus avoiding the necessity
of dissolving the substance treated as a step preliminary to the charging of the
decomposition chamber, and which shall avoid the clogging of the fluid in the
decomposition chamber with the soluble products of decomposition, shall
permit the withdrawal of the soluble products of the decomposition as they
are formed and in
a practically pure state, while the process is going
on, and which may be carried out by the aid of simple apparatus and

page_text: shall be comparatively inexpensive; third, to provide a process of electrical decom-
position by which all danger of recombination of the products of the decom-
position may be removed; and fourth, to provide a simple, effective, and
comparatively inexpensive apparatus for carrying out the process.
These objects are attained in the process of and apparatus for the electrical
decomposition of solid substances herein described, the apparatus being illustrated
in the drawings which accompany and form a part of this specification, in which
the same reference numerals indicate the same or corresponding parts, and in
which:-
Figure 1 is an elevation and partial longitudinal section of the apparatus;
Figure 2 is a transverse section of the apparatus; and Figure 3 is a detail section
illustrating a device for feeding down the substance to be treated to the field
between the electrodes, which may be substituted for the device for the same
purpose shown in Figures 1 and 2.
In my process the substance to be treated is placed between the electrodes in a
solid state. It is then moistened with water or other solvent of the substance
treated to permit the ready passage of an electric current and the action of the
current on the substance, and an electric current is passed through the mass.
During the time the electric current is passing I cause a stream of water or other
solvent to percolate through the mass undergoing treatment, which keeps it moist
and in condition to be acted upon by the electric current, and insures a uniform
action upon the substance treated, and in flowing away carries with it the soluble
products of decomposition. Only enough water is used to keep the mass under-
going treatment moist throughout, and I avoid the use of water in such quantity
that the water itself is decomposed to any considerable extent, as work done in
decomposing water is wasted. By using merely enough water to keep the mass
under treatment moist, I avoid the decomposition of the water itself by the electric
current, and do not require an electric current of as great potential as has been
required by most of the former systems of electrical decomposition, in which the
substance treated is first dissolved and the solution treated, and in which there is a large
quantity of free fluid present between the electrodes. In such systems, it has
usually been found necessary or preferable to employ a porous layer or partition of
some sort, separating the positive and negativo electrodes, and which is ordinarily
termed a diaphragm," to prevent the substances liberated at the positive and
negative electrodes from re-combining. The diaphragm adds considerably to the
electrical resistance of the cell, and so necessitates a higher potential than is required
by my system.
As my system of decomposition is conducted, there is practically no free fluid
between the electrodes, and what fluid is present is saturated with the substance
under treatment, and does not absorb the gas which may be liberated at one
electrode. The absence of free fluid is due to the fact that the mass under treatment
is merely kept moist with the fluid.
L
This process also avoids all of the troubles and inconveniences to which systems of
decomposition in which the substance to be treated is first fused are necessarily
subject.
In the drawings, 1 is the tank within which the treatment takes place, the walls
of which are formed of some electric non-conductor. 2 is the negative electrode,
which should be composed of some substance which will not be acted upon by the
fluids in the tank, and which, for the decomposition of the salts of sodium and
potassium, may with advantage be zinc. This electrode, as shown in the drawings,
is a perforated plate, though as the equivalent of this construction a series of bars
connected together and placed close to each other may be used. The electrode
forms a false bottom to the tank. Beneath the electrode 2 is an inclined false
bottom 3, which serves to catch the fluid as it flows through the perforations in the
electrode. 4, 4, are the positive electrodes, and should be composed of some material
which will not be affected by the fluids or gases within the tank, and which may
with advantage be carbon rods or sticks.. They are supported at the ends in

page_text: insulating plugs 5. The ends of both the positive and negative electrodes project
through the sides of the tank 1, and are connected to conductors leading to terminals
of a dynamo 6 or other source of current. Near the positive electrodes are one or
more pipes 7 for introducing water, and which are perforated to spray the water
and so distribute it uniformly over the substance treated.
In the decomposition of many substances, such for instance as potassium and
sodium chloride, one product of the decomposition is a gas, which, if collected,
may be utilized to advantage. For this reason the tank may be provided with a
cover 8 which may be closed and which will prevent the escape of gas. In the
drawings this cover is shown as bolted down, but other well known fastening
devices which permit a more ready removal of the cover may be used instead. In
order to draw off the gaseous products of decomposition a pipe 9 is provided which
may if necessary be connected to an exhaust pump. Instead of drawing off the
gas it may be absorbed in an absorbent material, such as lime, within the tank 1.
In the drawings I have shown a removable tray 14 for holding lime, in the upper
part of the tank, and have shown passages 15 in the sides of the tank through
which the gas may pass into the upper part of the tank into proximity with the
lime in the tray 14.
In order that the operation may be continued uniformly for a considerable
period of time without removing the cover 8 to recharge the apparatus, I provide in
the tank 1, and above the positive electrodes, a series of polyagonal bars 10
revolubly mounted in the sides of the tank 1 and geared together so that they may
be revolved together. The bars are close to each other and prevent the passege of
the substance to be treated except when they are revolved. When they are
revolved they feed the substance down slowly.
Instead of using a series of polyagonal bars 10 for feeding down the substance
to be treated, I can use instead a simpler feeding device, shown in Figure 3, and
consisting of two perforated plates, 11 and 12, the lower, 11, being stationary, and
the upper, 12, being movable laterally and being provided with an eccentric rod
and eccentric by which it may be vibrated.
My process is applicable to the treatment of any solid substance capable of being
decomposed electrically, whether such substances be in the form of cakes, lumps,
crystals, granules or powder. The feeding apparatus illustrated in Figures 1
and 2 is of course applicable only to the feeding of substances in a granular or
pulverulent state, or the lumps or crystals of which are of no very great size. If
it is required to treat substances in cakes or lumps of considerable size some other
appropriate feeding mechanism must be used or it may be necessary to charge by
hand from time to time.
The manner of carrying out the process may be illustrated by describing the
production of chlorine and sodium hydrate or hydroxide from sodium chloride,
i.e. common salt. The salt, in granular or crystaline form, is placed between the
positive and negative electrodes and also in the chamber above the grate bars 10,
and the mass of salt which lies between the electrodes is moistened by water
from the pipes 7. The water dissolves a portion of the salt, and holds it in solution
in condition to be acted upon by the electric current. When the mass is moist
throughout the electric current is turned on and passes from the positive electrodes
to the negative electrode. In passing through the mass of salt the electric current
decomposes the salt in solution into its elements, vis, metallic sodium and chlorine
gas. The chlorine gas rises and is drawn through the pipe 9, and may be utilized
in various ways, as for instance, in the production of bleaching powder. It may
also be absorbed by an absorbent material, as lime, in the tank 14. The metallic
sodium liberated, immediately combines with the water to form caustic soda, or
sodium hydrate or hydroxide, as it is more properly termed. The caustic soda
is carried by the water through the perforations in the negative electrode and falls
upon the inclined false bottom 3 from whence it runs out through the pipe 13.
Water i: constantly supplied, but in such quantity only as suffies acidly to keep
the mass moist, to take the place of the water which combines with the sodium

page_text: and flows off through the perforations in the lower electrode. If the quantity of
water used be properly regulated the fluid which flows from the pipe 13 will be
a strong solution of caustic soda, containing little or no sodium chloride.
It will be observed that as the decomposition goes on the products of the
decomposition are carried away immediately. In former processes of decom-
position, where the salt has first been dissolved, the caustic soda is left in the
solution when formed and so clogs the solution. Morcover as the process proceeds
the salt solution becomes weaker, and it is impracticable to utilize all of the salt
in the solution.
The electrical resistance, in my process, is proportionately less than in those
systems and apparatus in which a solution is treated and in which diaphragms
separating the electrodes are employed. In my process the chlorine is liberated
above the greater part of the mass of salt. The wasteful decomposition of the
water itself by the electric current is practically avoided, and this is an advantage,
aside from the current saved, because when the water itself is decomposed, some
ozone is generated and attacks the positive electrodes, soon destroying them. All
of these objections are avoided in the process above described. The treatment of
the salt in a solid state, instead of dissolving it before placing it in the apparatus,
has the further advantage that the apparatus may be much smaller than when
solutions are used.
During the progress of the treatment, the grate bars 10 are slowly revolved,
or, ir the form of feeding device shown in Figure 3 is used, the upper plate 12 is
vibrated. This feeds the salt down slowly into the lower portion of the tank, thus
supplying fresh salt to take the place of that which has been decomposed, and keeping
the quantity of salt between the electrodes practically constant. This insures uni-
formity in the operation of the apparatus and keeps the potential required
practically uniform.
Sodium carbonate, when treated in a similar manner, is decomposed into carbonic
acid gas and sodium oxide. The sodium oxide when formed is immediately
converted into the hydrated oxide or hydroxide, and passes off as before.
Salts of substances similar to the sodium salts, such as, for instance, the potassium
salts, may be treated in the same manner with corresponding reactions.
Instead of introducing water through the pipes 7, as a liquid, I may introduce
it as steam, which will immediately become liquid in the tank. Steam, however,
penetrates the mass undergoing treatment more readily than a liquid.
I do not mean to imply, by terming the process herein described a process for
the decomposition of solid substances, that the decomposition takes place while the
substance under treatment is in a solid condition. I so term my process to dis-
tinguish it from the processes mest generally used heretofore, in which the
substance to be decomposed is dissolved as a preliminary step, and in which an
excess of the solution is present while the decomposition is going on, so that a
diaphragm or other device is required to prevent recombination of the products of
the decomposition. It is probable that in my system only that portion of the
substance which is actually in solution at any given instant is undergoing decom-
position at that instant. By my process, however, the amount of fluid present is
80 small that it is always saturated with the substance treated, and for this reason
does not absorb readily any gas which may be liberated.
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 18:
1. The herein described process of decomposing solid substances electrically,
which consists in placing the substance to be acted upon between electrodes, and
causing a liquid solvent of the substance treated to percolate through the mass
in such quantity as suffices merely to keep the mass moist, without submerging
the mass in said fluid, and passing an electric current through the mass,
substantially as described.

page_text: 2. The herein described process of decomposing soluble salts of sodium and like
substances, which consists in placing the salt in a solid state between electrodes, and
causing water to percolate through the mass in such quantity as sustices merely to
keep the mass moist, without submerging the mass in the water, and passing an
electric current through the mass, substantially as described.
3. The herein described process of decomposing sodium chloride and like chlorides
electrically, which consists in placing the sodium or other chloride in a solid state
between electrodes, and causing water to percolate through the mass in such
quantity as suffices merely to keep the mass moist, without submerging the mass in
the water, and passing an electric current through the mass, substantially as
described.
4. In an apparatus for electrically decomposing solid substances, the combina-
tion, with a tank adapted to contain the substance treated, of electrodes within said
tank, placed one above the other and between which the substance treated may be
placed, and adapted to be connected to an electric generator and to pass an electric
current through the mass to be treated, the upper electrode having passages through
which the substance to be treated may descend to the space between the electrodes, and
the lower electrode being provided with openings through which fluids may pass,
means for supplying a fluid to the mass within said tank, and means for collecting.
the soluble products of the decomposition which flow through the openings in said
lower electrode, substantially as described.
5. In an apparatus for electrically decomposing solid substances, the combination,
with a tank adapted to contain the substance treated, of electrodes within said
tank, placed one above the other and between which the substance treated may be
placeu, and adapted to be connected to an electric generator and to pass an electric
current through the mass to be treated, the upper electrode having passages
through which the substance to be treated may descend between the electrodes,
and the lower electrode being a perforated plate forming the bottom of the chamber
in said tank in which the decomposition takes place, means for supplying a fluid to
the mass within said tank, and a collecting chamber below said lower electrode
adapted to receive the soluble products of the decomposition which flow through
said electrode, substantially as described.
Dated this 7th day of March 1990.
EDWARDS AND CO.,
65 and 66, Chancery Lane, London, Agents for the Applicant.