Production of Chloride of Zinc or of Zinc and Chlorine,
Year: 1896

page_text: Date of Application, 3rd Nov., 1896
Complete Specification Left. 3rd Sept., 1897-Accepted, 3rd Nov. 1897
Production of Chloride of Zinc or of Zinc and Chlorine,
I CARL HOEPPNER Doctor of Philosophy, Electrochemist E.C. London De Keyser's
Royal Hotel Victoria Embankment do hereby declare the nature of this invention to
be as follows:-
In order to produce in places like London or wherever sulphuric acid is
manufactured and sulphates of Alkalies have a market, cheap chloride of zinc and
chlorine, I proceed as follows:
Pure zinc ores or complex sulphide ores containing zinc, iron, lead, silver or
other metals, like the ores of Brokenhill in New South Wales, are roasted to oxides
in suitable furnaces and the sulphurous acid thus set free is converted into sulphuric
acid by the ordinary process.
The sulphuric acid so obtained from the zinc ores or obtained from other sources
is then mixed with cheap chlorides, such as chloride of potassium or of sodium, and
heated so as to produce sulphates of alkalies and gaseous hydrochloric acid.
In separate stirring vessels the latter is brought into contact with water or diluted
chloride solutions and with the roasted zinc ores containing an excess of oxide of
zinc.
Thus a neutral or basic solution of zinc is formed containing also other valuable
metals, if there were any present in the ore, but containing only small quantities of
iron.
Very conveniently the treatment of the roasted ores may be executed so that the
strong acid solution first acts upon a portion of the ores to a certain degree already
freed from its metal contents by a previous treatment thus extracting the last traces
of zinc and dissolving some oxide of iron and then in a warm state acts upon other
fresh quantities of ores containing an excess of oxide of zinc.
In this way the perchloride of iron forined by the action of an excess of
hydrochloric acid upon the exhausted zinc ores-eventually with the addition of free
chlorine-will dissolve the rest of the sulphides of zinc, lead, copper and silver or of
metallic silver and gold left in the ores and the resulting zinc chloride solution will
then by the contact with the fresh roasted zinc ore loose its free acid as well as most
of its iron contents.
The residue of the ores is finally washed with warın water or warm chloride
solutions so as to extract all the chloride of lead.
The final result is that a neutral or slightly basic solution of chloride of zinc is
obtained containing also other valuable metals extracted from the ore.
From this solution the gold, silver, lead and other metals are precipitated one after
another or simultaneously by known means such as cooling or electrolysis or metallic
lead and zinc or sulphides or oxides or carbonates or chromates and so on.
Also the rest of the iron and manganese left in the solutions is then precipitated
by chloride of lime and finally EL sufficiently pure solution of chloride of zinc is
obtained which is subjected to electrolysis giving chlorine and pure zinc.
By such electrolysis the solution is partially freed from its contents of zinc and
then containing not more than 1-3 % of zinc it is used over again for the absorption
of hydrochloric acid, the extraction of ores and electrolysis.

page_text: The steam or the heat necessary for the work of the sulphuric acid chambers may
very conveniently be taken from the purified exhaust steam of the engines driving
the dynamos or from distilling weak chloride solutions.
The sulphates of alkali obtained in this process can be sold on the market.
There is always a good market for great quantities of sulphate of potash as a
manure.
Before the sulphide ores are roasted they may be treated with acids such as
hydrochloric acid or substances like cupric chloride or perchloride of iron with the
purpose of extracting the silver and lead or part of the latter which if present in too
great quantities might be disagreeable in the roasting process.
The solutions to be electrolysed ought to contain sufficient quantities of chloride
of sodiuin, potassium, calcium or magnesium so as to secure a good conductivity of
the electric current.
When too much diluted they ought to be concentrated again by distillation.
The described method of utilizing hydrochloric acid for the production of Chlorine
is far more economical in its effects than the Weldon and Deacon processes since the
electrolysis of zinc chloride solutions conforming to previous patents of mine may be
considered a solved problem.
Dated this Third day of November 1896
COMPLETE SPECIFICATION.
Production of Chloride of Zinc or of Zinc and Chlorine.
I, CARL HOEPFNER, formerly residing at De Keyser's Royal Hotel, Victoria
Embankment, London, but now of Helgolander-Ufer 21, Berlin, N.W., in the Empire
of Germany, Chemist, 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:-
In order to produce cheap chlorides of zinc and chlorine, more especially in
places where sulphuric acid is manufactured and sulphates of alkalies have a market,
I proceed as follows:
Pure zinc ores or complex sulphide ores containing zinc, iron, lead, silver or other
inetals, like the ores of Brokenhill in New South Wales, are roasted to oxides in
suitable furnaces and the sulphurous acid thus set free is converted into common
sulphuric acid by the ordinary process.
The sulphuric acid so obtained from the zinc ores (or obtained from other sources)
and containing much water is then mixed with cheap chlorides, such as chloride of
potassium or of sodium, and heated so as to produce gaseous hydrochloric acid and
sulphates of alkalies.
In separate stirring vessels the gaseous hydrochloric acid containing much steam is
brought into contact with water or chloride solutions (such as chloride of zinc or
chloride of calcium solutions) and with the roasted zinc ores containing an
of oxide of zinc. Calamine ores however if subjected to this process need no
roasting.
The treatinent of the ores may conveniently be carried on in such a manner that
the strong acid solution first acts upon a portion of the ores which has already to
a certain degree been freed from its inetal contents by a previous treatment (thus
extracting the last traces of soluble zinc and dissolving some oxide of iron) and
then in a warm state, acts upon other fresh quantities of ores containing an excess
of oxide of zinc.

page_text: In this way the perchloride of iron formed by the action of an excess of hydrochloric
acid upon the exhausted zinc ores will dissolve the rest of the oxides and sulphides of
zine, lead, copper and silver or metallic silver and gold left in the ores, and the
resulting zinc chloride solution will then, by contact with the fresh warm roasted
zinc ore, lose its free acid as well as most of its iron. The aforesaid action may, if
desired, be supported by adding an aqueous solution of free chlorine to the
hydrochloric acid or to the exhausted ores under treatment; or by leading chlorine
gas to the exhausted ores to be treated by the said hydrochloric neid or into the said
acid-itself. This dissolving operation may also be supported by adding an aqueous
solution of free chlorine gas to the said solution containing perchloride of iron; or
by leading free chlorine gas into the said solution or to the ores under treatment.
In this way nearly the whole of the hydrochloric acid is turned to profit.
The residue of the ores is finally washed with warm water or warm chloride solutions
so as to extract all the chloride of lead.
The final result is that a neutral or slightly basic solution of chloride of xine is
obtained containing also other valuable metals extracted from the ores.
From this solution the gold, silver, lead and other metals that are more electro-
negative than zinc are precipitated one after another or simultaneously by known
ineans such as by cooling, by electrolysis, by metallic lead and zine, or by sulphides,
oxides, carbonates, chromates, or other suitable compounds. I prefer electrolysis for
the purpose of complete purification.
The remainder of the iron and manganese left in the solutions is precipitated by
chloride of lime or similar chemical agents such as chlorine and hydrate of lime or
hydmte of xine, until finally a sufficiently pure solution of chloride of zine is
obtained, which is subjected to electrolysis giving chlorine and pure xine.
By such electrolysis the solution is partially freed from its contents of zine and
then (containing not more than 1% to 3% of zinc) it is used over again for the
absorption of hydrochloric acid, the extraction of metals from the ores and
electrolysis.
The steain necessary for working the sulphuric acid chambers, or other acid
producing apparatus, may very conveniently be obtained from the steam generated
by distilling weak ebloride solutions, more particularly such that have undergone the
electrolytic treatment; or the said steam inay be obtained partly from the parified
exhaust steam of the engines driving the dynamos and other machinery employed.
Such utilization of waste steam enables great economy to be effected.
The sulphates of alkalies obtained in this process can be sold on the market.
There is always a good market for sulphate of potash as a manure.
Before the sulphide ores are roasted they may be treated with acids such as
hydrochloric or substances like cupric chloride or perchloride of iron, for the purpose
of extracting the silver and lead, or part of the laiter, which if present in too great
quantities might be objectionable in the roasting process.
The solutions to be electrolysed should contain such quantities of chloride of
sodium, potassium, calcium or magnesium as to ensure a good conductivity of the
electric current.
When too much diluted as for instance by the water contained in the sulphuric
neid and hydrochloric acid respectively, the solutions should be concentrated again
by distillation, and the steam so obtained be utilized as above specified.
The described method of utilizing hydrochloric acid for the production of chlorine
is far more economical than the Weldon and Deacon processes, since the electrolysis
of zine chloride solutions, in view of previous patents of mine, may be considered
a solved problem. It is obvious that in the same way also the hydrochloric acid
derived from the Hargreaves process or similar processes may be utilized, the
necessary steam for this process being obtained from steam generated by the
distillation of weak chloride solutions or partly obtained from the exhaust steam of
the engines as already stated.
If the ores to be subjected to this process, for example calamine, contain much calcium
or magnesium, a certain quantity of hydrochloric acid will be transformed into

page_text: chloride of magnesium or chloride of calcium which latter according to a previous
patent of mine can be used to produce chloride of zinc.
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. A process for obtaining from ores a solution of chloride of zinc or metallic zine
and chlorine substantially as described.
2. In the aforesaid process the condensation of gaseous hydrochloric acid by
chloride solutions or by a mixture of chloride solutions with finely divided zinc ores,
substantially as described.
3. In the aforesaid process the methodical and economical extraction of zinc by
hydrochloric acid substantially as described.
4. In the aforesaid process the complete purification of the zinc chloride solutions
from metals more electro-negative than zinc and the precipitation of silver and
lead from the same, prior to the electrolytical production of zine, substantially as
described.
5. In the aforesaid process the concentration of the circulating solution when it
becomes too diluted, substantially as described.
6. In the aforesaid process the feeding of the sulphuric or other acid producing
apparatus with steam generated by concentrating the circulating solution of chlorides
or with the exhaust steam of the steam engines substantially as described.
7. In the aforesaid process the treatment of the mixed sulphide ores with cupric
chloride or perchloride of iron substantially as described, and for the purpose set
forth.
8. In the aforesaid process the production of sulphates of potassium substantially
as described and for the purpose set forth.
Dated this 2nd day of September 1897.
HASELTINE, LAKE & Co,
45 Southampton Buildings, London, W.C., Agents for the Applicant.