New Process for Extracting Zinc from Pyrites Containing Blende, the Waste of the same and from any other Ores Containing Sulphide of Zino.
Year: 1888

page_text: New Process for Extracting Zinc from Pyrites Containing Blende,
the Waste of the same, and from any other Ores Containing
Sulphide of Zino.
I, JOSEF PERINO, of Charlottenburg near Berlin, Prussia, 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:-
The new process has for its object to convert in a simple and direct manner the
sulphide of zinc of materials containing blende into soluble sulphate of zinc by the
oxidising action of nitrate of iron at low temperatures (say at from 50 to 200° C).
The nitrate of iron is very readily decomposed in the presence of oxidisable substances,
such as sulphide of zinc, already at temperatures below 100° C., in producing
sesquioxide of iron, nitrous gases, and free oxygen, the latter acting in its nascent
state directly upon the sulphide of zinc for converting it into sulphate.
The material containing blende is very intimately mixed with nitrate of iron in
the proportions of about five parts of the latter to one part of the amount of zinc
contained in the former and the mixture is exposed in suitable clay retorts to a
temperature of about 50° C. and the heating is then gradually increased up to 150° C.
and 200° as long as there are brown-red nitrous vapours still escaping.
When the reaction is finished, which will be the case after 1 or 2 hours, according
to the increase of the temperature, the residue is lixiviated with hot water, whereby
the sulphate of zinc enters in solution. In addition to the other constituents of the
ore, there is in the residue of the lye the sesquioxide of iron resulting from the
decomposition of the nitric iron salt. When, beside sulphide of zinc, the ore contains
also sulphuret of iron, the latter oxidising with more difficulty than sulphide of zinc,
will remain intact on suitably regulating the temperature. By this means a perfectly
pure lye of sulphate of zinc may be obtained.
The nitrous vapours escaping during the process of conversion into sulphate, are
conducted by means of an air current into receivers filled with water, and the formation
of nitric acid takes place therein in a proportionately short space of time. The nitric
acid is then used for producing nitrate of iron.

page_text: In working the waste of pyrites containing sulphide of zinc the yield of oxide of
zinc resulting from the roasting operation remains always in the residue of the lye.
To produce nitrate of iron, this residue is treated with the recovered nitric acid,
whereby the sesquioxide of iron is dissolved into nitrate of iron. The oxide of zinc
which has been added, is dissolved at the same time by the nitric acid. By a repeated
use of these produced nitrates as a material for converting into sulphates, and by
treating the residue with the recovered nitric acid, the nitric salt of iron is gradually
more and more enriched with nitrate of zine; when the yield of zinc is sufficient, the
sesquioxide of iron is precipitated by means of an admixture of washed oxide of zinc,
and a solution of pure nitrate of zinc is obtained. The latter is inspissated, the residue
of vaporisation is heated to a light glow and oxide of zinc and nitrous vapours are
thereby obtained, the latter of which are absorbed by water and converted into nitric
acid, which is employed in the above described manner for producing nitrate of
iron.
The solution of sulphate of zinc obtained by this process is then further worked
according to any known method.
Having now particularly described and ascertained the nature of this inven-
tion and in what manner the same is to be performed I declare that what I
claim is :-
The above described process for extracting zinc from pyrites containing blende or
from the waste of the same, or from any other ores or products containing sulphide of
zine, by means of nitrate of iron used as a means for converting into sulphates in such
that an intimate mixture of the nitrate of iron with the ores is gradually
heated in suitable apparatus up to about 200° C. and the residue lixiviated with hot
water, whereby a solution of pure sulphate of zinc is obtained which may be further
worked according to any suitable method for any intended purpose.
a manner,
ABEL & IMRAY,
Agents for the Applicant.