Improvements in the Manufacture of Chloride of Zinc and other Metal Chlorides, applicable also to the Manufacture of Acetate or Sulphate of Zino.
Year: 1895

page_text: PROVISIONAL SPECIFICATION.
Improvements in the Manufacture of Chloride of Zinc and other
Metal Chlorides, applicable also to the Manufacture of Acetate
or Sulphate of Zino.
I, CARL HOEPFNER, of 36 Frankfurterstrasse, Giessen, in the Empire of
Germany, Doctor of Philosophy, do hereby declare the nature of this invention to
be as follows:-
In order to obtain chloride of zinc for electrolytical purposes, I treat zincblende
and other ores or minerals which contain sulphide of zinc, as follows:
An acid or acids of nitrogen, chiefly pure nitric acid or nitric acid obtained from
saltpetre by the action thereon of sulphuric acid, is or are mixed with water and
hydrochloric acid or with materials or mixtures capable of developing or giving off
hydrochloric acid, for example chloride of sodium or other suitable chlorides and
sulphuric acid or acetic acid or sulphurous acid (which is to be oxydised to
sulphuric acid by this treatment), and with the powdered zinc ore. This mixture
must be made in such proportions and in such moderate concentrations and
temperatures, as to prevent the oxydation of the sulphur as well as the reduction
of the nitric gases to nitrogen or nitrous oxide (NO) and so as to recuperate
nearly all of the used nitric acid as gases easily to be regenerated. A solution of
chloride of zinc is thus obtained and the sulphur set free. The nitric gases are
utilised for the manufacture of sulphuric acid in any known way or regenerated to
nitric acid, which is obtained in a very pure state or used to treat fresh quantities
of ores.
In the described treatment of zincblende with nitric acid, air or oxygen may be
present so as to regenerate the nitric gases on the spot.
The chloride of zinc solution so obtained is neutralised and then either
evaporated or subjected to freezing by which treatment sodium sulphate is
separated. In some cases the elimination of the sulphate of soda need not be
complete and can be effected by simply mixing the solution with pieces of ice or a
portion of any refrigeration salt solution.
The resulting chloride of zinc solution, which may contain small quantities of
uitric salts, is purified from metals which are more electronegative than zinc, and
from any other impurities and finally electrolysed.
The greater part of the chloride of zinc is decomposed into chlorine and zinc by
the electrolysis. The residual diluted solution of chloride of zinc is if necessary
concentrated and used again in the aforesaid manner in the treatment of zinc ores
and in the regeneration of nitric acid as diluting agent. In this way any loss of
nitric acid is prevented. It is advisable for economical reasons, to carry out this
process by using nitrate of soda (Chilian saltpetre or soda saltpetre), sodium
chloride and common sulphuric acid and to utilise the regenerated pure nitric acid.
for other purposes.
The chloride of sodium can of course also be replaced by chloride of potassium
or magnesium chloride, or other suitable chlorides."

page_text: The addition of chloride of sodium or other chlorides to the sulphuric acid, can
be avoided, if instead of chloride of zinc, zinc acetate or sulphate is to be formed,
which latter can then be transformed into chloride of zinc or subjected to
electrolysis in its original state.
Other minerals and materials can be treated as above described with reference
to zinc blende and the metals be extracted as sulphates, acetates.
For instance lead as chloride of lead (PbCl,), nickel as chloride of nickel
(NiCl2), silver as chloride of silver (AgCl) and even iron as perchloride of iron
(Fe,C), which latter is a very suitable solvent of zinc from roasted zinc ores,
whereas the former metals can one after another be precipitated from the solution
by electricity or by chemical agents, such as metals, for instance zinc dust.
Copper can be extracted as cupric chloride which after the reduction to.
cuprous chloride can be similarly electrolysed. This reduction can take place by
sulphurous acid.
By this process free sulphur is obtained which contributes greatly to the
economical result of the process.
"This process can also be used for the treatment of sulphurets and other suitable
compounds of cobalt, nickel, copper, lead and other valuable metals except oxydes
of metals. It is advisable to treat the materials which are to be subjected to this
nitric process previously with an acid such as HCl or H,SO, so as to save nitric
acid and to dissolve soluble oxydes or sulphurets.
:.
The H2S thus produced can be utilized in different ways. The sulphuric acid
required in this process can be economically produced by the reaction of sulphurous.
Acid upon a solution of cupric chloride.
!
2 CuCl + 2 HgO + SO, :
=
Cu,Cl + H₂SO + 2 HCI.
Improvements in the Manufacture of Chloride of Zinc and other
: Metal Chlorides, applicable also to the Manufacture of Acetate
or Sulphate of Zinc.
::
1, CARL HOEPFNER, of 2 Helgolünder Ufer, Berlin formerly of 36 Frank-
furterstrasse, Giessen, in the Empire of Germany, Doctor of Philosophy, 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
30
In order to obtain chloride of zinc for electrolytical purposes, 1 treat zinc blende
and other ores or minerals which contain sulphide of zinc, as follows:
An acid or acids of nitrogen, chiefly pure nitric acid or nitric acid obtained from
saltpetre by the action thereon of sulphuric acid, is or are mixed with water and
hydrochloric acid or with materials or mixtures capable of developing or giving off
bydrochloric acid, for example chloride of. sodium or other suitable chlorides and
sulphuric acid or acetic acid or sulphurous acid (which is to be oxidized to
sulphuric acid by this treatment) and with the powdered zinc ore.
This
s mixture

page_text: is made in such proportions and in such moderate concentrations and temperatures,
as to separate as far as possible the whole of the nitric acid in the form of nitric
oxide N() as to prevent the oxidation of the sulphur as well as the reduction of the
nitric gases to nitrogen or nitrous oxide (N,O) and so as to recuperate nearly all of
the used nitric acid as gases easily to be regenerated. A solution of chloride of
zinc is thus obtained and the sulphur set free.
The reaction will take place conforming to the following equations:
2 HNO, +3 ZnS + 6 HCI
-
3 ZnCl, +3 S + 2 NO + 4 H₂O.
and consequently no excess of sulphuric or nitric acid nor excess of heat is to be
employed and during the reaction a good mixing of the acid with the mineral is
required.
The solution so obtained should contain about 10-20 per cent. of zine.
The nitric gases may be conveniently utilized for the manufacture of sulphuric
acid in the known way or regenerated to nitric acid, which is obtained in a very
pure state or preferably used over and over again to treat fresh quantities of ores.
In this treatment zinc blende with nitric acid, air or oxygen may be present so
as to regenerate the nitric gases on the spot.
The chloride of zinc solution so obtained is neutralized and then either
evaporated or if containing sulphate of alkalies, subjected to freezing by which
treatment sodium sulphate is separated.
The elimination of the sulphate of soda need not always be complete and can
sometimes be effected by simply mixing the solution with pieces of ice or a portion
of any refrigerated salt solution, for instance chloride of zinc.
The resulting chloride of zinc solution is purified from metals which are more
electronegative than zinc, and from any other impurities and finally electrolysed or
used to other purposes, for instance the manufacture of oxide of zinc.
As a rule the greater part of the chloride of zinc so obtained is decomposed into
chlorine and zinc by the electrolysis. The residual diluted solution of chloride of
zinc is used again in the aforesaid manner in the treatment of zinc ores, serving in
the regeneration of nitric acid as diluting agent. In this circular way any loss of
nitric acid is prevented.
The chloride of sodium can of course also be replaced by chloride of potassium,
or magnesium chloride, or other suitable chlorides.
If it is desired to produce sulphate or other salts of zinc instead of chloride of
zinc obviously no hydrochloric acid or chloride is necessary for this process,
conforming to the first equation. Such sulphate or salt of zinc may then at will
and by known methods or by any known chemical precipitant be transformed into
any desirable compound of zinc.
In an analogous manner, to that described for the production of chloride of zinc
or of sulphate of zinc and the like from zinc ores containing sulphide of zinc, also
chlorides, sulphates or another salt of other metals can be obtained from ores or
materials containing such metals in the form of their sulphides; for instance, lead
may be obtained as chloride of lead (PbCl,) or acetate of lead from ores containing
sulphide of lead, or nickel is obtained as chloride of nickel (NiCl,) or sulphate of
nickel or as acetate from materials containing sulphide of nickel, or silver may be
obtained as chloride of silver (AgCl) or iron can also be obtained in an analogous
manner as ferric chloride (Fe,C₁₁)-this chloride is a very good solvent of zinc
from roasted zinc ores-or ferric sulphate [Fe,(SO),] or acetate, or copper is
obtainable as sulphate, chloride or acetate from material, containing sulphide of
copper, in an analogous way to that described for the extraction of zinc from
materials containing sulphide of zinc.

page_text: Following equations may illustrate the chemical reactions thereby taking place
by way of example.
=
3 CuS +2 HNO3 + 6 HCI 3 CuCl + 3 S + ? NO + 4 HO
3 PbS + 2 HNO, + 6 C₂HO₂ = 3 Pb (С₂H₂O₂), + 3 S + 2 NO + 4 H,O.
Copper can be extracted as cupric chloride which after the reduction to cuprous
chloride can be similarly electrolysed.
By this process the free sulphur obtained contributes greatly to the economical
result of the process.
It is advisable to treat the materials which are to be subjected to this nitric
process previously with an acid such as HCl or H,SO, so as to save nitric acid
and to dissolve soluble oxides or sulphurets.
The HS thus produced can be utilized in different ways.
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. The process of treating materials or minerals containing metallic sulphides,
preferably sulphide of zinc, by mixing such materials with water and nitro-
geniferous acid or acids or materials capable of developing such acid or acids in
the presence of the acids to be combined with the metals of the said materials (such
as hydrochloric, acetic, or sulphuric acid) or in the presence of materials or
mixtures capable of developing such acids, in order to obtain a solution of chloride
or oxygen salts of the said metals adapted to be employed for the electrolytical or
chemical separation of the metals, in which process the materials or minerals to be
treated with water and the nitrogeniferous and other acids or materials are mixed
in such a way in such proportions and in such moderate concentrations and
temperatures as to prevent as much as possible the oxydation of the sulphur as
well as the reduction of the nitrogeniferous gases to nitrogen or nitrous
oxide (N,O) and so as to recuperate nearly all of the used nitrogeniferous acid as
gases which are easily regenerated.
2. The manufacture of ferric salts suitable as a solvent of zinc from roasted zinc
ores by treating ferriferous ores or materials containing sulphides of iron by the
process referred to in Claim 1.
3. For the process referred to in Claims 1 and 2 the preparatory treatment of
the said materials or minerals to be subjected to the said processes with an acid, so
as to dissolve soluble oxides or sulphurets and to save nitrogeniferous acid.
Doted this 11th der of Jen 1806
HASELTINE, LAKE & Co.,
45 Southampton Buildings, London, W.C., Agents for the Applicant.