Improvements in Treating the Residual Products of Certain Manufactures and in Treating Certain Metallic Ores for the Manufacture of Chlorine.
Year: 1893

page_text: Date of Application, 15th Dec., 1893
Complete Specification Left. 5th Oct.. 1894-Accepted, 10th Nov., 1894
PROVISIONAL SPECIFICATION.
Improvements in Treating the Residual Products of Certain
Manufactures and in Treating Certain Metallic Ores for the
Manufacture of Chlorine.
1 EDWIN JAMES HUNT, of Wednesbury in the County of Stafford, Manufac-
turing Chemist do hereby declare the nature of this invention to be as follows:-
My invention has reference to the manufacture of chlorine by the electrolytic
decomposition of chloride of zine and chloride of iron and consists of the improve-
ments hereinafter described in obtaining the said chlorides by treating residual
products of certain manufactures and also by treating ores containing zinc.
In the ordinary process of galvanizing and tinning iron the sheets or articles to
be galvanized or tinned are made chemically clean by being treated with dilute
sulphuric or hydrochloric acid or a mixture of these acids. When sulphuric acid is
used the spent acid consists essentially of a solution of sulphate of iron. This
solution when treated with cbloride of sodium or common salt yields chloride of
iron and sulphate of soda. The latter may be crystallized out leaving a sufficiently
pure solution of chloride of irou to be operated upon by an electric current
preferably from a dynamo when the chloride of iron is resolved into gaseous
chlorine and metallic iron. The former is collected and applied to the manufacture
of bleaching powder or to other purposes to which chlorine is applicable. The
metallic iron which is of great purity may be used for ordinary purposes or for
purposes where iron of great purity is required.
The residual sulphate of iron obtained in other processes may be treated in the
way described.
Metallic ores whether poor or rich in zinc may be treated by roasting by which
the sulphide of zinc contained in them is converted into oxide. This is extracted
from the roasted ore by sulphuric acid and the sulphate of zinc obtained treated
with common salt whereby a mixed solution of chloride of zinc and sulphate of soda
is obtained and the sulphate of soda being crystallized out the remaining solution
of chloride of zinc is resolved into chlorine and metallic zinc by electrolysis as
hereinbefore explained.
In the galvanizing process the bath of melted zinc is covered with a layer of
salammoniac. This in part volatilizes and in part gives rise to the formation of
chloride of zinc and the skimmings of the galvanizing bath consist of a mixture
of chloride of zinc salammoniae and oxide of zinc. The chloride of zinc from its
exceeding solubility may be removed by the use of water cautiously added, or the
whole may be treated with water and the salammoniac crystallized out from the
solution. The remaining liquid consists essentially of a solution of chloride of zinc,
sufficiently pure to be treated in the manner already described:
The remaining oxide of zinc may be dissolved in sulpliuric acid and chloride of
sodium added to the solution which is afterwards treated in the manner herein before
described.
Although my invention has for its primary object the manufacture of chlorine
yet the resulting iron and zinc have more than the commercial value of these
metals.
Dated this 15th-day of December 1893.
W. T. WHITEMAN,.
Agent for the Applicant.

page_text: COMPLETE SPECIFICATION.
Improvements in Treating the Residual Products of Certain
Manufactures and in Treating Certain Metallic Ores for the
Manufacture of Chlorine.
I EDWIN JAMES HUNT, of Wednesbury in the County of Stafford, Manu-
facturing Chemist, do hereby declare the nature of my invention and in what
manner the same is to be performed to be particularly described and ascertained
in and by the following statement :-
My invention has reference to the manufacture of chlorine by the electrolytic
decomposition of chloride of zinc and chloride of iron and consists of the improve-
ments hereinafter described in obtaining the said chlorides by treating residual
products of certain manufactures and also by treating ores containing zinc.
In the ordinary process of galvanizing and tinning iron the sheets or articles to
be galvanized or tinned are made chemically clean by being treated with dilute
sulphuric acid or hydrochloric acid or a mixture of these acids. When sulphuric
acid is used the spent acid consists essentially of a solution of sulphate of iron. This
solution when treated with chloride of sodium or common salt yields chloride of
iron and sulphate of soda. The latter may for the most part be crystallized out
leaving a sufficiently pure solution of chloride of iron to be operated upon by an
electric current preferably from a dynamo when the chloride of iron is resolved
into gaseous chlorine and metallic iron. The former is collected and applied to
the manufacture of bleaching powder or to other purposes to which chlorine is
applicable. The metallic iron which is of great purity may be used for ordinary
purposes or for special purposes where iron of great purity is required.
The residual sulphate of iron obtained in other processes may be treated in the
way described.
Metallic ores containing zinc, whether rich or poor in zinc, may be treated by
roasting by which the sulphide of zinc contained in them is converted into
oxide. This is extracted from the roasted ore by sulphuric acid and the sulphate
of zinc obtained treated with common salt whereby a mixed solution of chloride of
zinc and sulphate of soda is obtained and the sulphate of soda being crystallized
out the remaining solution of chloride of zinc is resolved into chlorine and metallic
zinc by electrolysis as herein before explained.
In the galvanizing process the bath of melted zinc is covered with a layer of
salammoniac. This in part volatilizes and in part gives rise to the formation of
chloride of zinc and the skimmings of the galvanizing bath consist of a mixture
of chloride of zinc, salammoniac and oxide of zinc. The chloride of zinc from its
exceeding solubility may be removed by the use of water cautiously added, or the
whole may be treated with water and the salammoniac crystallized out from the
solution. The remaining liquid consists essentially of a solution of chloride of zinc
sufficiently pure to be treated in the manner already described.
The remaining oxide of zinc may be dissolved in sulphuric acid and chloride of
sodium added to the solution which is afterwards treated in the manner hereinbefore
described.
Although my invention has for its primary object the manufacture of chlorine
yet the resulting iron and zinc have in consequence of their purity more than the
commercial value of these metals.
.In the accompanying drawing Figure 1 represents in elevation and Figure 2
in vertical section, partly in elevation, the apparatus I employ in electrolysing
chloride of iron or chloride of zinc according to my invention; Figure 3 represents

page_text: 5
50
half plan and half horizontal section of Figure
an of Figure 2.
and Figure repressu
The same letters of reference indicate the same parts in the several figures of
e drawing.
For simplicity of description I will refer only to the decomposing of proto-
aloride of iron.
a is the containing vessel in which is placed the solution of the protochloride to
e operated upon, the said vessel being made of iron or earthenware or other
aterial not injuriously acted upon by chloride of iron. When the vessel a is of
etal it is supported upon insulators a³, a³ to prevent leakage of the electric
urrent: bis a vessel of porous earthenware having a series of holes *, * which
oles are filled with slag wool, asbestos or other porous or fibrous material which
vill permit of the passage through it when impregnated with the solution under
operation of the electric current employed. The upper edge of the vessel b has in
t an annular depression or trough 6 into which the cap or lute c, made preferably
of lead, dips. Water being poured into the trough 6 a water joint is formed.
The bottom 6 of the vessel b is preferably made separate from the cylindrical or
body part of the vessel, the said body part fitting on the bottom in the manner
shown in Figure 2, and having preferably a packing or washer 6 of slag wool or
the like. The bottom 6 rests upon the blocks 6°. Strips d of sheet iron are hung
Where the said vessel a is of metal it is
around the interior of the vessel a.
unnecessary to connect these strips of iron d together but when the said vessel is
made of a non-metallic material the said strips must be connected by means of a
metal band or otherwise electrically connected: e is a solid or hollow cylinder of
carbon forming one of the electrodes, the strips of iron d forming the other
electrode. In order to connect the conductor f electrically with the carbon
electrode e the strand of wires of which it is composed is opened out at its end as
best seen in Figure 4, the open end occupying a shallow recess in the closed top of
the electrode e. Melted lead being poured into the said recess effects the electrical
A packing 9 (see
connection of the conductor f with the carbon electrode e.
cap c and
Figure 2) of slag wool or asbestos makes a gas tight joint between the
the carbon electrode c. The electrical connection of the conductor f with the strips of
iron d constituting the other electrode is effected by the binding screw i fixed on
the vessel a when the said vessel is made of metal. When the said vessel a is made
of a non-metallic substance the binding screw i for the reception of the conductor f
is attached to the top of one of the metallically connected strips d.
A continuous or non-alternating electric current preferably from a dynamo being
passed in the proper direction by means of the conductors through the solution of
chloride of iron with which the vessel a is nearly filled the said chloride is
decomposed into metallic iron which is deposited on the strips d and gaseous
The said
chlorine which is evolved at the surface of the carbon electrode e.
chlorine rising into the cap c passes by means of the pipe having the water joints l
and to the main k by which it is delivered into chambers containing quick lime
for the manufacture of bleaching powder.
The chlorine may be applied to purposes other than the manufacture of bleaching
powder.
The evolution of chlorine does not commence until the electric current has
passed sufficiently long through the solution to convert the protochloride into
perchloride of iron when the evolution of gaseous chlorine immediately commences.
m is a funnel for the introduction of the solution into the vessel a.
I prefer to use a solution of protochloride of iron having the specific gravity
indicated by sixty degrees of Twaddel's hydrometer but I do not limit myself
to this strength of solution. I prefer to operate on the solution at ordinary
temperatures. I prefer to use from fifteen to thirty of the decomposing vessels
5.5 represented, each of which may be capable of holding two hundred to three hundred
gallons connected in series as indicated in the drawing and to employ an electric
current preferably that of a dynamo having an electro motive force of about two

page_text: hundred ampères but I do not limit myself to these details, the electrical current
and the solution of chloride being proportioned to each other according to the well
known principles of electro-metallurgy..
In decomposing chloride of zinc I proceed in the manner already indicated with
respect to chloride of iron. In treating a solution. of. chloride. of zinc the
decomposition immediately commences on the passage of the electric current
through the solution, there being no formation of a per salt as described with
reference to protochloride of iron.
In operating upon chloride of zinc the plates d on which the zinc is deposited are
preferably made of zinc.
I prefer to operate on a solution of chloride of zinc having a specific gravity of
60 to 70 degrees indicated on Twaddel's hydrometer.
Having now particularly described and ascertained the nature of my inven-
tion and in what manner the same is to be performed I declare that I claim as
my invention of "Improvements in treating the residual products of certain
manufactures and in treating certain metallic ores for the manufacture of
chlorine";-
First. Concentrating by evaporation the dilute solution of chloride of iron
obtained as a residual product in the galvanizing or tinning of iron sheets or
articles to the specific gravity or about the specific gravity indicated by sixty
degrees of Twaddel's hydrometer and treating the said solution by an electrical
current, preferably that of a dynamo, whereby the said chloride of iron is first
converted into perchloride of iron which perchloride is by further action of the
electrical current resolved into chlorine and metallic iron substantially as herein-
before described and illustrated in the accompanying drawing.
Secondly. Treating the solution of sulphate of iron obtained as a residual product
in the galvanizing or tinning of iron sheets or articles with chloride of sodium or
common salt whereby chloride of iron and sulphate of soda are produced;
separating the greater part of the sulphate of soda from the chloride of iron by
concentration and crystallization and treating the remaining solution by the process
herein before described and claimed in the prior claim.
Thirdly. Treating the skimmings of galvanizing baths in the manner hereinbefore
described so as to produce therefrom a crude solution of chloride of zinc and
treating the said solution by an electrical current so as to resolve it into chlorine
and metallic zinc substantially as herein before described and illustrated in the
accompanying drawing.
Fourthly. Treating metallic ores containing zinc in the manner hereinbefore
described so as to obtain therefrom sulphate of zinc, treating the solution of
sulphate of zinc with chloride of sodium or common salt so as to obtain a solution
containing chloride of zinc and sulphate of soda, crystallizing out the greater part of
the sulphate of soda and operating upon the crude solution thus obtained by an
electrical current, preferably that of a dynamo, so as to decompose it into chlorine
and metallic zinc substantially as herein before described and illustrated in the
accompanying drawing.
Dated the Fifth day of October 1894