Improvements in the Manufacture of Chlorine.
Year: 1896

page_text: PROVISIONAL SPECIFICATION.
Improvements in the Manufacture of Chlorine.
We EDWIN JAMES HUNT of Myrod House Wednesbury in the County of Stafford,
Manufacturing Chemist and EDWARD FAIRLIE WATSON, of No. 11 Church Street,
Wolverhampton, in the County of Stafford Electrical Engineer do hereby declare
the nature of this Invention to be as follows:-
Our invention consists of the process or processes hereinafter described whereby
chlorine is obtained by the electrolytic decomposition of a crude solution of
protochloride of iron, such as is obtained as a waste or residual product in the
treatment of iron with hydrochloric acid in certain manufacturing processes.
We operate upon the said crude solution of protochloride of iron for the
manufacture of chlorine in the following manner.
We take a tank, either metallic or non-metallic, in which we place a porous vessel
or we take a tank which is divided into two parts by a porous diaphragm. In the
porous vessel or in one division of the tank, we place a rod or plate of carbon and into
that portion of the division or cell containing the carbon rod or plate we introduce a
strong solution of common salt or chloride of sodium, the other portion of the tank
being filled with the solution of protochloride of iron.
Through the arrangement described we pass an electrical current, preferably from
a dynamo, the connections being so made that the current enters at the carbon which
constitutes the anode of the arrangement and passing through the electrolytes, that
is, the solutions of common salt and protochloride of iron and also through the
separating porous diaphragm, passes out at the tank, or where a non-metallic tank is
employed at strips of iron suspended in the protochloride of iron, the said metallic
tank or strips of iron constituting the cathode.
By the electrolytic action set up, chlorine is evolved at the anode, the said chlorine
being collected and directed into chambers containing quicklime for the manufacture
of bleaching powder, or employed for any other purpose to which free chlorine is or
may be applicable.
Pure iron is deposited on the cathode strips which, when a sufficient thickness has
been obtained are removed and replaced by fresh ones, the deposited iron being used
for purposes for which very pure iron is applicable.
The process described may either be intermittent or continuous; that is, the
solution of protochloride of iron may be operated upon by the electrical current until
its strength has been so far reduced that it cannot any longer be economically
employed when it may be drawn off and replaced by a strong solution; or a
continuous and gentle stream of a strong solution of protochloride of iron may be
introduced into the cell or compartment containing the cathode and by means of an
overflow pipe an equal quantity of the partially exhausted solution be allowed to run
out of the apparatus.
Although we have described our invention as carried into effect by the use of a

page_text: strong solution of common salt or chloride of sodium yet we wish it to be understood
that in place of the said chloride of sodium, chloride of potassium or the chlorides
of the earthy metals may be employed.
Dated this eighteenth day of December 1896.
W. T. WHITEMAN
Agent for the Applicants.
CUMI DEMIE DIEVITICATION.
Improvements in the Manufacture of Chlorine.
We, EDWIN JAMES HUNT, of Myrod House, Wednesbury, in the County of Staffor,
Manufacturing Chemist, and EDWARD FAIRLIE WATSON, of No. 11 Church Street,
Wolverhampton, in the County of Stafford, Electrical Engineer, do hereby declare the
nature of our invention and in what manner the same is to be performed to be
particularly described and ascertained in and by the following statement ;--
Our invention consists of the process or processes hereinafter described whereby
chlorine is obtained by the electrolytic decomposition of a crude solution of proto-
chloride of iron, such as is obtained as a waste or residual product in the treatment
of iron with hydrochloric acid in certain manufacturing processes, such for example
as the process commonly known as galvanizing.
We operate upon the crude solution of protochloride of iron for the manufacture of
.chlorine in the following manner.
We take a tank, either metallic or non-metallic, in which we place a porous vessel;
or we take a tank which is divided into two parts by a porous diaphragm. In the
porous vessel, or in one division of the tank, we place a rod or plate of carbon and
into that portion of the division or cell containing the carbon rod or plate we intro-
duce a strong or saturated solution of common salt or chloride of sodium, the other
portion of the tank being filled with the solution of proto-chloride of iron.
Through the arrangement described we pass an electrical current, preferably from
a dynamo, the connections being so made that the current enters at the carbon which
coustitutes the anode of the arrangement and passing through the electrolytes, that
is, the solutions of common salt and protochloride of iron and also through the
separating porous diaphragm, passes out at the tank, or where a non-metallic tank is
employed at strips of iron suspended in the protochloride of iron, the said metallic
tank or strips of iron constituting the cathode.
By the electrolytic action set up, chlorine is evolved at the anode, the said chlorine
being collected and directed into chambers containing quicklime for the manufacture
of bleaching powder, or employed for any other purpose to which free chlorine is or
may be applicable..
Pure iron is deposited on the cathode strips which when a sufficient thickness has
been obtained are removed and replaced by fresh ones, the deposited iron being used
for purposes for which very pure iron is applicable.
The process described may either be intermittent or continuous; that is, the
solution of protochloride of iron may be operated upon by the electrical current until
its strength has been so far reduced that it cannot any longer be economically
employed when it may be drawn off and replaced by a strong solution; or a continuous
and gentle stream of a strong solution of protochloride of iron may be introduced
into the cell or compartment containing the cathode and by means of an overflow pipe
an equal quantity of the partially exhausted solution be allowed to run out of the
apparatus.
Although we have described our invention as carried into effect by the use of a

page_text: strong solution of common salt or chloride of sodium yet we wish it to be understood
that in place of the said chloride of sodium, chloride of potassium or the chlorides of
the earthy metals may be employed.
Having described the nature of our invention we will proceed to explain in detail
the manner of carrying the same into effect.
The crude solution of proto-chloride of iron or ferrous chloride obtained as a
residual product in the pickling or treating of iron preparatory to galvanizing the
same contains besides proto-chloride of iron or ferrous chloride a portion of perchloride
of iron or ferric chloride and also some free hydrochloric acid.
We treat the said solution in the following manner;-
The free hydrochloric acid is first neutralised by treating the liquid with scrap iron
in a wooden tank for a few days. The resulting solution, containing only ferrous and
ferric chlorides, is heated with more scrap iron in iron tanks. The ferric chloride is
thereby decomposed into ferrous chloride and free hydrochloric acid. Most of the latter
passes off with the steam, the remainder forming ferrous chloride with the scrap iron.
The solution now containing only ferrous chloride, is then evaporated down to a
specific gravity preferably of about 1.4.
In order that our invention may be the better understood we have represented in
the accompanying Drawing the apparatus we employ in carrying our said invention
into effect.
Figure 1 represents in end elevation and Figure 2 in cross section one of the tanks
which we employ; Figure 3 is a longitudinal section of a portion of the same and
Figure 4 represents a part of the tank in plan.
The same letters of reference indicate the same parts in the several Figures of the
Drawing.
The tanks are made preferably of pitch pine and of a size about ten feet long by
two and a half feet deep by two and a quarter feet wide at top and a foot and a half
at bottom, but we do not limit ourselves to any particular proportions. Two square
pitch pine battens marked' a run the whole length of the tank on each side of the
bottom b. On these battens a at intervals of about ten and a half inches, boards c
seven, inches wide by a foot and a half long by one inch thick are placed: transversely
the said boards e forning the bottoms of the porous compartments. The number of
porous compartments depends on the strength of the electrical current employed
the portion of one compartment for every forty ampères of current being a suitable pro-
portion when the compartments are of the dimensions hereinbefore given. The two
sides of the porous compartment are formed of two slabs d of porous material, prefer-
ably firebrick, the edges of which are packed watertight in grooves formed by
battens c on the sides of the tank and on the false bottom c preferably by the use
of tar and tar clay.
In each compartment we place a plate of carbon having a size preferably two
feet and a half by two feet by two inches and we close the top of each compartment by
a lead cap h made gas tight round the joints by the use of tar and tar clay. The
said tar clay consists of three parts of clay to one part of tar, these materials being
well kneaded together.
These carbons g form the anodes of the cells, all the anodes in one tank being
connected together and to the cathodes of the next tank. The anodes of the first
tank of the series of tanks are connected to the positive terminal of the dynamo by
the copper cable i. From each cell or compartment a lead pipe k conducts the
chlorine evolved into the chlorine main.
Along the tops of the sides and ends of the tanks run strips of iron / fastened
metallically together and connected at one end by the gun metal connector m to the
copper cable from the anodes of the previous tank, the strips of iron of the last tank
of the series of tanks being connected to the negative terminal of the dynamo.
Between the porous compartments, rods of iron n are placed and are bolted at each
end to the iron strips. On these, strips of thin sheet iron are hung dipping into the
ferrous chloride solution with which the spaces between the several porous compart-
ments are filled. These thin strips of iron form the cathodes of the arrangement and

page_text: receive the deposit of iron. When the deposit is thick enough, say a quarter of an
inch or more, they are removed and fresh strips are substituted.
When the ferrous chloride solution gets weakened to a specific gravity of about 1-2
the brine in the inner cell decomposes, caustic soda being formed at the cathodes
which caustic soda uniting with the ferrous chloride forms a green or red precipitate
of hydrated protoxide or peroxide of iron. It is therefore advisable never to let the
strength of the ferrous chloride solution fall below 1.25.
Although we have only described our invention in connection with the use of a
solution of protochloride of iron obtained as a waste or residual product in the treat-
ment of iron with hydrochloric acid obtained in the galvanizing process yet we wish
it to be understood that our improvements are applicable to the obtaining of chlorine
from solutions of proto-chloride of iron obtained as a residual product in other like
manufacturing processes.
And although we prefer to employ a dynamo as the source of electricity employed
in carrying our invention into effect yet electricity from other sources such for
example as primary voltaic batteries may be employed.
Having now particularly described and ascertained the nature of our invention and
in what manner the same is to be performed we declare that what we claim as our
invention of "Improvements in the inanufacture of chlorine "
The use of solutions of chlorides of sodium or potassium or chlorides of the earthy
metals in the anode compartments of an electrolytic vat when ferrous chloride is
decomposed electrically to obtain therefrom chlorine and metallic iron, substantially
as hereinbefore described and illustrated in the accompanying drawing.
Dated the Sixth day of September 1897
EDWIN JAMES HUNT.
EDWARD FAIRLIE WATSON.