IMPROVEMENTS IN THE MANUFACTURE OF SULPHIDE AND OTHER COMPOUNDS OF ZINC, AND IN THE PRODUCTION OF BYE-PRODUCTS RESULTING THEREFROM
Year: 1878

page_text: LETTERS PATENT to Carl Friedrich Claus, of Charlotte Street, Fitzroy Square,
in the County of Middlesex, Chemist, for the Invention of "IMPROVEMENTS IN
THE MANUFACTURE OF SULPHIDE AND OTHER COMPOUNDS OF ZINC, AND IN
THE PRODUCTION OF BYE-PRODUCTS RESULTING THEREFROM."
Sealed the 4th February 1879, and dated the 16th August 1878.
PROVISIONAL SPECIFICATION left by the said Carl Friedrich Claus at the
Office of the Commissioners of Patents on the 10th August 1878.
CARL FRIEDRICH CLAUS, of Charlotte Street, Fitzroy Square, in the County of
Middlesex, Chemist. "IMPROVEMENTS IN THE MANUFACTURE OF SULPHIDE AND
OTHER COMPOUNDS OF ZINC, AND IN THE PRODUCTION OF BYE-PRODUCTS RE-
SULTING THEREFROM."
This Invention relates to improvements in the manufacture of sulphide and other
compounds of zinc, and in the production of bye-products resulting therefrom, and
consists,-
First. In a process for the production of chloride of zinc from the galvanizers'
refuse, called skimmings, which consists chiefly of chloride of zinc, oxide of zinc,
some sal ammoniac, and considerable quantities of salts of iron. The object of this
part of the said Invention being to separate the chloride of zinc from the salts of
iron with which it is contaminated: The said separation I propose to effect by
heating the skimmings, and in various ways, that is to say,-
A: On the bed of a reverberatory furnace, either by itself, or mixed with charcoal
or small coke, or mixed intimately with chloride of calcium or chloride of magnesium,
with or without the admixture of charcoal or coke.
B. In a kiln or cupola furnace, to which air blast may be applied, the skimmings
being mixed with coke alone, or with coke and chloride of calcium or chloride of
magnesium. If the heating of the skimmings in the cupola, together with coke
alone is adopted, muriatic acid gas may be admitted into the cupola at the same
time. By heating the said substances or mixtures to a red heat; the chloride of
D

page_text: zinc becomes volatilized, leaving the iron behind. Its vapors are conducted into a
condenser similar in construction to a muriatic acid condenser, where, by the appli-
cation of water, the same as in a muriatic acid tower, the vapors become condensed
to a solution of chloride of zinc in water.
pro-
Instead of using the skimmings, I also use mixtures of zinc ashes, roasted blende,
or calamine, with chloride of calcium, or chloride of magnesium, and charcoal, or
coke, and treat the same as described above in reference to skimmings. Or I
duce first a solution of impure chloride of zinc by dissolving skimmings, zinc ashes,
roasted blende, or calamine in hydrochloric acid, which, when desiccated, I treat in
the same manner described above in reference to skimmings. The solution of
chloride of zinc thus obtained from the condenser, I propose to use as an ingredient
for the manufacture of sulphide of zinc in the manner described in the Specification
of Letters Patent granted to John Bryson Orr, dated the 10th February, A.D. 1874,
No. 517, or in the different manners or processes herein-after described for the
manufacture of sulphide of zinc to be used as a white pigment, and which processes
form part of this Invention.
The said Invention consists, secondly, in the production of sulphide of zinc, and in
the production of mixtures of sulphide of zinc and sulphate of baryta in the
following ways, and by the following re-actions, that is to say,-
(1.) I take chloride of zinc free from iron, lead, and similar impurities, and add
thereto an equivalent quantity of sulphide of ammonium. Sulphide of zinc is
formed, and chloride of ammonium. The sulphide of zinc is separated by filtration,
washed, dried, and treated as described in the said Specification of John Bryson
Orr. To the chloride of ammonium I add an equivalent quantity of sulphide of
barium in solution, whereby sulphide of ammonium and chloride of barium are
produced. The sulphide of ammonium is separated from the chloride of barium by
distilling off and condensing the sulphide of ammonium, or it may be distilled with
lime. Or I may precipitate the oxide of zinc with caustic ammonia separate, by
decantation or filtration and wash. I then add the sulphide of barium solution to
the oxide of zinc, when sulphide of zinc and caustic baryta is formed. Or I re-
dissolve the oxide of zinc in ammonia, and then add sulphide of barium. The
chloride of ammonium may be treated as above described, or it may be used as
hereafter described, or it may be decomposed by lime, the ammonia distilled off and
condensed.
According to another method, I take a solution of sulphate of zinc, add an
equivalent quantity of ammonia or such quantities as may be required to form the
desired proportions of sulphate of zinc and sulphate of baryta, allow the oxide of
zinc to subside, decant, and wash; add sulphide of barium or redissolve the oxide
in excess of ammonia first before adding the sulphide of barium. The sulphate of
ammonia may be distilled with lime, and the ammonia condensed in water, or it
may be decomposed by sulphide of barium for the production of sulphide of am-
monium, and white saleable sulphate of baryta.
My Invention consists, thirdly, in the extraction of zinc from roasted blende or
calamine, from zinc ashes or skimmings, by boiling the same with the solutions of
chloride of ammonium obtained in the various operations described herein, and in
utilizing such solutions of zinc in the manner described in reference to chloride of
zinc in the production of sulphide of zinc.
My Invention consists, fourthly, in the extraction of zinc from roasted blende, or
calamine from zinc ashes, or sometimes also from zinc skimmings by means of
caustic alkalies, in preference by caustic ammonia and caustic potash, for the purpose
of producing from such solutions sulphide of zinc to be used as pigment, and for
producing valuable bye-products. I effect the solution by macerating or digesting
the pulverized materials or calcined ores in caustic ammonia or potash.
My Invention consists, fifthly, in the precipitation from such alkaline solutions of
oxide of zinc, the sulphide of zinc by sulphides of alkalies, or by sulphide of barium.
Thus, if I have a solution of oxide of zinc in ammonia, I may precipitate by means
of sulphide of ammonium, and I obtain sulphide of zinc and caustic ammonia. The
:

page_text: caustic ammonia is separated from the sulphido of zinc by distillation. If I preci-
pitate with sulphide of barium, I obtain caustic ammonia and caustic baryta mixed.
After the mixed solution is separated from the zinc precipitate by filtration, I
separate the caustic baryta from the ammonia by distillation. The caustic baryta
may be boiled down and crystallised, and is a saleable article of value. Or it may
be used for producing caustic potash by decomposing sulphate of potash with it.
But the ammoniacal solution of oxide of zinc I decompose also by sulphide of
potassium, when caustic potash and caustic ammonia are produced, which also may
be separated by distillation. If I have produced a solution of oxide of zinc by
caustic potassa, I prefer to precipitate by means of sulphide of potassium, and I
obtain a quantity of caustic potassa as product, equivalent to the sulphide of zinc
formed. Or if I precipitate with sulphide of barium, I obtain a mixture of caustic
baryta and potassa, which may, if necessary, be separated by crystallization, but can
also be used for decomposing a quantity of sulphate of potassa equivalent to the
hydrate of baryta in solution.
In the same way, sulphide of ammonium may be used to precipitate the zinc from
the potassa solution. What has been said in reference to hydrate of potassa and
sulphide of potassium would also apply to the corresponding soda compounds, but
their application is not so profitable.
It is obvious that if mixtures of sulphide of zinc and sulphate of baryta are
desired for a pigment, sulphate of zinc can be added in the desired proportion to
which two equivalents of caustic ammonia have been previously added, or what is
more profitable to do, is to add the sulphate of baryta (in the required quantity),
which was produced by decomposing sulphate of potash by means of caustic baryta,
due care being taken to have said precipitate free from iron or colouring matter,
:
}

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed by
the said Carl Friedrich Claus in the Great Seal-Patent Office on the 14th
February 1879.
-
CARL FRIEDRICH CLAUS, of Charlotte Street, Fitzroy Square, in the County of
Middlesex, Chemist. "IMPROVEMENTS IN THE MANUFACTURE OF SULPHIDE AND
OTHER COMPOUNDS OF ZINC, AND IN THE PRODUCTION OF BYE-PRODUCTS RE-
SULTING THEREFROM."
. This Invention relates to improvements in the manufacture of sulphide and other
compounds of zinc, and in the production of bye-products resulting therefrom, as
herein-after specified.
The said Invention comprises the manufacture of a white pigment consisting of
sulphide of zinc, or of mixtures in various proportions of sulphide of zinc and
sulphate of baryta, by which manufacture certain valuable bye-products are
obtained. I precipitate sulphide of zinc from solutions of zinc in solutions of
caustic alkalies (such as potassa, ammonia, and soda) by means of solutions of any
of the sulphides of the alkalies (namely, the sulphides of potassium, ammonia, and
sodium), or by solutions of sulphide of barium.
The precipitate of sulphide of zinc can be used alone, but a superior pigment is
obtained if precipitated sulphate of baryta is mixed with the same.
The sulphuric
acid necessary for the formation of the sulphate of baryta is derived in all the
different methods herein described from sulphate of potassa or soda. By the action
of the oxide of zinc in the alkaline solution upon sulphide of barium, sulphide of
zine and caustic (or hydrate of) baryta will be produced. By the action of the
latter upon sulphate of potassa, sulphate of baryta and caustic (or hydrate of)
potassa will be produced. The sulphate of baryta formed is mixed with or added
to the precipitate of sulphide of zine. This result can be effected either by the said
precipitate of sulphate (baryta being produced in a separate operation, and then
adding it to the precipitate of sulphide of zinc in the desired proportions), or the
precipitation of the sulphate of baryta may be effected simultaneously, that is to
say, in the same liquor, with the sulphide of zinc, by adding the sulphate of potassa
thereto (preferably in solution). The latter method ensures a more intimate mixture,
and is therefore preferred.
The alkaline solutions of zinc are produced by digesting or macerating materials
containing zine or oxide of zinc (such as roasted calamine, roasted blende, zinc ashes,
or galvanizers' skimmings) in the solutions of caustic alkalies named above, but
metallic zinc may also be dissolved in the caustic alkalies. If skimmings (flux) are
used it is well to first remove the chlorides they contain by treating the same with
cream of lime, and washing with water before dissolving them in alkali. To these
alkaline solutions I add (if a mixture of sulphide of zinc and sulphate of baryta is
desired to be produced) a solution of sulphate of potassa in such quantities as to
form the desired proportion of sulphide of zinc and sulphate of baryta; then a.
solution of sulphide of barium is added in sufficient quantity to precipitate the
sulphuric acid of the sulphate of potassa, and to form the equivalent quantity of
sulphate of baryta. Thus, if a mixture of one equivalent of sulphide of zinc and
one equivalent of sulphate of baryta is to be produced, one equivalent of sulphate
of potassa and one equivalent of sulphide of barium must be added to the alkaline
solution of zinc. The filtrate in this case contains all the potassa which was used
as the solvent of the zinc oxide, and in addition a quantity of caustic potassa is
formed equivalent to the quantity of sulphate of potassa added to the liquor.
This caustic potassa may be utilized in any convenient manner.
If more than one equivalent of sulphide of zinc to one equivalent of sulphate of
baryta is desired to be obtained (for instance, two of sulphide of zinc. to one of
sulphate of baryta), and the extra or additional equivalent of zinc is precipitated by
sulphide of barium, then the filtrate will contain also one more equivalent of caustic

page_text: baryta in solution. This may be separated from the caustic potassa by crystal-
lization and utilized, but it is preferred to effect the precipitation of the extra
equivalent of zinc by means of sulphide of potassium. What has been said or will
be described in reference to potassa and its compounds is also applicable to the
corresponding compounds of soda, but the use of soda compounds is not so
profitable.
The sulphide of potassium, of sodium, or ammonium may be prepared advan-
tageously for the above purpose by decomposing the sulphate of potassa, of soda,
and of ammonia by means of sulphide of barium.
I prefer to precipitate the sulphide of zinc by the sulphide of the base in which
the zinc is dissolved, but it is possible also to precipitate the zinc dissolved in one
alkali by the sulphide of another alkali. Thus, for instance, if I have a solution of
oxide of zinc in ammonia, I may precipitate by means of sulphide of ammonium,
and I obtain sulphide of zinc and ammonia. The ammonia is separated from the
sulphide of zinc by filtration and distillation. If I precipitate with sulphide of
barium I obtain ammonia and caustic baryta mixed. After the mixed solution is
separated from the zinc precipitate by filtration I separate the caustic baryta from
the ammonia by distillation.
The caustic baryta may be boiled down and crystallized, and is in this condition a
saleable article, or it may be used for decomposing sulphate of potassa as described;
but the ammoniacal solution of oxide of zinc may also be decomposed by sulphide
of potassium, and the caustic potassa and ammonia produced by this operation may.
be separated by distillation; or, vice versa, from a solution of oxide of zinc in potassa
the zinc may be precipitated by means of sulphide of ammonium, or by sulphide of
barium; the filtrate in this case will contain caustic baryta and potassa or
ammonia.
The precipitate of sulphide of zinc, or the more useful mixtures of sulphide of
zine with sulphate of baryta, obtained by any of the various operations or methods
above described, is separated by filtration (or filtration and distillation respectively)
from the mother liquor, and is dried and calcined in closed muffle furnaces or in
retorts. The calcined product is then cooled out of contact with the air, or by
throwing the same while hot from the furnace into water; it is then ground,
washed, and levigated, and is then ready to be used as pigment.
According to another but less advantageous method I also produce sulphide of
zinc by precipitation from chloride of zinc by means of sulphide of ammonium.
Mixtures of sulphide of zinc and sulphate of baryta I produce (for instance, if two
equivalents of the former to one equivalent of the latter be desired) by taking one
equivalent of chloride and one equivalent of sulphate of zinc, and adding thereto
two equivalents of sulphide of ammonium. Sulphate of ammonia and chloride of
ammonium is formed, and two equivalents of sulphide of zinc. I then add two
equivalents of sulphide of barium, and I obtain two equivalents of sulphide of zinc,
one equivalent of sulphate of baryta, and in solution one equivalent of chloride of
barium and two equivalents of sulphide of ammonium. After the precipitate is
separated from the liquid by filtration I distill off the sulphide of ammonium in
filtrate from the chloride of barium. The sulphide of ammonium I may use
repeatedly for the same purpose.
It is obvious that by altering the quantities of the materials any other proportion
of sulphide of zinc and sulphate of baryta may be produced.
Having thus fully described my said Invention, and the manner of performing the
same, I wish it to be understood that I claim,-
First. The manufacture of sulphide of zinc by precipitating the same from solu-
tions of zinc in caustic alkalies by means of solutions of sulphides of alkalies or
sulphide of barium as above described.
Second. The manufacture of mixtures of sulphide of zinc and sulphate of baryta
by precipitation from solutions of zinc in caustic alkalies by means of sulphide of
barium and sulphate of potassa (or soda) alone, or by the aid of sulphides of the
alkalies, as above set forth.
-

page_text: Third. The production of caustic baryta, potassa, ammonia, and soda from the
sulphides of these alkalies, and of caustic potassa or soda from their sulphates as
bye-products in the manufacture of sulphide of zinc and mixtures of sulphide of
zinc and sulphate of baryta, as above set forth:
Fourth: The manufacture of sulphide of zinc by the action of sulphide of ammo
nium upon chloride of zinc as above set forth.,
}
Fifth. The manufacture of mixtures of sulphide of zinc and sulphate of baryta by
the action of sulphide of ammonium upon chloride and sulphate of zinc, and of
sulphide of barium upon the sulphate of ammonia formed therein, as above set
forth.
Sixth. The utilization of the precipitates of sulphide of zinc and of the latter, and
sulphate of baryta produced as described, for the manufacture therefrom by known
means of a white pigment, as above set forth.
.
:
In witness whereof, I, the said Carl Friedrich Claus, have hereunto set my
hand and seal, this Seventh day of February, in the year of our Lord One
thousand eight hundred and seventy-nine.
AADI DIEDRICH CUL ATTO
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