Year: 1888

page_text: I, CHARLES FREDERICK CROSELMIRE, doing business at 115 to 123 Chestnut
Street, in the City of Newark, County of Essex, and State of New Jersey, one of the
United States of America, Metallurgist, 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:-
My invention consists in the process of extracting pure zinc by roasting the
pulverized zinciferous ore, and then subjecting the same to an aerated acid bath, and
finally depositing or precipitating the zinc, substantially as I will now proceed to
particularly set forth and claim.
It is well known that great loss has occurred in separating zinc from zinciferous
ores and the zinc obtained was impure, and where the ore contained the precious
metals, and especially silver, much of the latter has been driven off in vapor with the
zine, in the operation of suiciting. In addition where there is a considerable percentage
of zinc with the silver it is impossible to carry on the smelting operation.
An effort has been made to get rid of the zinc in galenas, carrying silver and
metallic sulphides and oxides, but with only partial success, and the zinc obtained
was impure, and when the ore contained iron and manganese, the zinc was largely
impregnated therewith.
The zine obtained by this last mentioned method is practically valueless as an
article of commerce, while the zinc obtained as the result of my method is chemically
pure.
In carrying out my process 1 first pulverize the ore, and then feed it dry into a
furnace, preferably a reverberatory one, and roast it, using either a blast, or a jet of
steam during the operation of roasting.

page_text: The heat is regulated so that a considerable percentage of the sulphide of zinc in the
ore is converted into a sulphate.
I next remove the roasted ore from the furnace into a tank containing a dilute
solution of sulphuric acid, which has the effect of holding the zinc in suspension,
while the other metals are precipitated, unless the ore contains iron and manganese,
the effect on which, by the acid, will be hereinafter explained.
The acid solution used is one of definite proportions and consists of one equivalent
of the acid for each equivalent of zinc, contained in the ore, which can be determined
by analysis. I have found by experiment that this is essential if chemically pure zinc
is to be obtained.
In other words if the ore should contain sixteen parts of zinc the acid solution
should be in the same proportion, or one part of acid to sixteen parts of water.
The proportions, parts and equivalents above referred to will be either by weight,
liquid, or other measure, but I do not desire to limit myself to the mode and means
employed in determining and measuring the said quantities.
The zinc in solution produced by the use of sulphuric acid will of course be a
sulphate.
If it should be desired to obtain the chloride of zinc instead, I substitute hydro-
chloric acid for sulphuric in the same proportions.
If the ore contains iron and manganese, it will be apparent that these two metals
will also be attacked by and largely held in solution by the action of the dilute
acid.
To get rid of these metals I introduce a blast into or through the tank containing
the acid and ore, and the result is that I throw down the iron and manganese by thus
forming peroxide thereof, leaving the zinc above in suspension.
I then draw off this solution, and the zinc may be deposited directly therefrom by
the use of a dynamo-electrical machine, or it may be precipitated as a carbonate or
oxide, by any of the known methods.
The precipitated pulp remaining in the tank, after the zinc solution is drawn off,
may be washed, moulded into bricks and smelted, or the different metals may be
separated by any of the usual and customary processes.
I use either a hot or cold blast in the tank to precipitate the iron and manganese as
a peroxide, and while I prefer to use superheated steam, I do not limit myself to the
use of such means.
It will be seen that the solution used is so weak that it does not attack the silver or
lead in the ore, and only to a limited degree the iron and manganese, and that
the two last named metals are wholly precipitated as peroxides by the blast, as already
stated.
I prefer to use the blast as already described through, or over the ore in the operation
of roasting, and generally do so in practice.
It is not absolutely essential that it be always used and might sometimes be dispensed
with; but in this event, a stronger and therefore more expensive acid solution would
be necessary, as there would be no sulpbates of the zinc, which would be readily
soluble in a weak acid.
The value and importance of my improvement will be readily apparent.
I am enabled to produce from zinciferous ores a chemically pure zine; a result
hitherto unattainable, and that too at a comparatively insignificant cost. Where
such ores contain silver by my process I leave the latter entirely free from zinc
alloy.
Having thus fully described my improvement, what I claim as my invention and
desire to secure by letters patent is-
Ist. That improvement in the art of obtaining pure zinc from zinciferous ores,
which consists in pulverizing the ore, roasting the pulverized ore in a suitable furnace,
and passing a blast through or over it, next immersing the roasted ore in dilute acid,
passing a blast through the solution until the impurities are oxidized, and finally

page_text: drawing off the zinc solution, and depositing or precipitating the zinc, substantially
as set forth.
2d. The process which consists in immersing roasted zinc ore in dilute acid,
passing an air blast through the solution until the impurities are oxidized, and finally
drawing off the zinc solution and depositing or precipitating the zinc, substantially as
set forth.
Dated this 20th day of March 1888.
CHARLES FREDERICK CROSELMIRE.
By Jensen & Son,
77, Chancery Lane, London, W.C.,
Patent Agents.