Improvements in and relating to the Extraction of Zine from its Ores.
Year: 1888

page_text: Date of Application, 10th Dec., 1888-Accepted, 24th Aug., 1889
Improvements in and relating to the Extraction of Zine from
its Ores.
I, HENRY AUGUST HUNICKE a Citizen of the United States residing at the City of
St. Louis State of Missouri United States of America Mining Engineer and 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:
This invention relates to an improved process of reducing zinc and is based on the
fact that metallic zine is oxidized by carbonic acid (CO,) between the temperature at
which zinc volatilizes and the temperature at which carbonic monoxide (CO) reduces
zinc oxide (Zn 0) and that above the last named (reduction) temperature metallic zinc is
not oxidized by carbonic acid and no reaction occurs. In carrying out the process the
ore to be reduced and the fuel, which serves to supply both the reducing-agent and
the means for maintaining the reduction temperature are immediately associated
within the reduction-chamber, as thereby the operation of reducing zinc is rendered
more continuous and economical, the appliances employed are not worn out as rapidly,
and various grades of ores can be readily and successfully treated in the reducing-
chamber.
To this end the process consists as follows; the ore to be reduced, together with a
proper amount of suitable fluxing material, but separate from the fuel to be used
within the reduction-chamber, must be heated in an oxidizing atmosphere, to the
temperature for reducing zinc before introducing it into the reduction-chamber. The
fuel used within the reduction-chamber, together with a proper amount of fluxing-
material, is similarly pre-heated.
The two, the ore and the fuel, as well as the flux mentioned, at the temperature
described, are then passed into the reduction chamber wherein, and by means of a
suitable supply of air introduced into the reduction-chamber for the purposes of the fuel-
combustion therein, the ore (Zn 0) combines with the carbonic monoxide, generated
from the burning-fuel, at a temperature at which carbonic monoxide reduces zinc-
oxide and zinc in the form of a vapour is produced. The temperature maintained
within the reduction-chamber should in practice exceed that at which zinc-oxide is
reduced in order thereby to have the entire interior of the reduction-chamber
including, the outlet leading to the condenser so heated as not to be chilled below
the zinc oxide reduction point whenever the réduction-chamber is opened to receive
the ore and fuel, and so that the zinc-vapour when once generated shall not be
chilled below the zinc-reduction point and, by reason of the carbonic acid present,
be reconverted into zinc oxide. The process is completed by transferring the zinc
vapour to a condenser and there converting it into liquid zinc as rapidly as it prac-
tically can be done. Successive lots of ore, fuel and flux are introduced into the
reduction-chamber as fast as those previously introduced are treated, and meanwhile
the air-supply is kept up, the air supply in practice being an air-blast such as
employed in many forms of cupola-furnaces but suitably graduated so as not only
to furnish the requisite amount to the fuel but, on the other hand, not to cause
such an extreme pressure outward as to carry the zinc-vapour too rapidly through
the condenser so as to be ultimately carried off with the other gases. The slag is
drawn off below the zone of fusion. The volatilized zinc is constantly going to
the condenser which is constructed and operated to effect the liquefaction of the
zinc in the shortest possible time. The other gaseous currents proceeding from the
cupola, which saving the outlet to the condenser is substantially a closed chamber,
pass with the zinc through the condenser and are finally discharged through an
outlet separate from that for the liquefied zinc. By pre-heating as described the

page_text: ore and fuel, and especially by pre-heating the ore, the temperature of the reduction-
chamber, especially at the immediate points where the zinc oxide is reduced, is not
chilled below the reducing temperature so as to cause reaction, and zinc oxide to
be formed within the reduction-chamber, and by condensing the zinc-vapour as
speedily as possible as is practicable the zinc oxide which otherwise is liable to form
at that point is in amount reduced to a minimum:.
The process as thus far described is a practical one, and by means of it valuable
results can be obtained. The carbonic acid however which is present may be carried
to the condenser and to some extent interfere with the operation. For, after the
various substances have been charged into the reduction-chamber and the reducing
operation is progressing, and the carbonic monoxide generated from the burning
fuel is combining with the zinc oxide (Zn 0) and reducing it to metallic zinc (Zn)
the gases going off consist not only of metallic zinc vapour (Zn) and unconsumed
carbonic monoxide but also of carbonic acid derived froin the reaction of carbonic
monoxide on zinc oxide (Zn O) and which carbonic acid owing to a lack of sufficient
time or other cause is not, by the carbon (C) in the fuel present, reduced to carbonic
monoxide but is carried to the condenser along with the zinc vapour and carbonic
monoxide. .
To prevent, or at least to hinder this and to provide an improved process of
reducing zinc is the aim of this invention which consists in passing the above described
gaseous current, consisting of zinc-vapour carbonic monoxide, and carbonic acid, and
heated as described through a chamber or passage charged with coke or any other
solid carbonaceous fuel which has been heated prior to charging, to a temperature at
least sufficient to reduce carbonic acid to carbonic monoxide and thereby causing the
carbonic acid to be so reduced to carbonic monoxide and then, delivering the zine-
vapour-carbonic monoxide current to a condenser of suitable construction whero the
zine vapour is liquefied and whence the carbonic monoxide is discharged to any
desirable point. That is to say, in the place of delivering the gaseous-current from
the reduction-chamber directly to the condenser, it is first brought into contact with
carbon, heated as described, and afterward delivered to the condenser. The more
thorough the contact, the more effectually is the process carried out. The condenser is
preferably one having cooling surfaces which are chilled by means of a cold liquid
circulating in the rear of thein.
I do not desire to be restricted to any special form of carbon-chamber or to any
special mode of subjecting the carbonic acid-bearing gaseous current to the heated
carbon therein, saving that such construction and mode be such as to promote the
action of the carbon in freeing the gaseous current of the carbonic acid and thereby
minimising the opportunity of the zinc vapour becoming oxidized in their passago to
the condenser and of the condenser becoming choked with oxidized zinc, and thereby
increasing the output of the plant and cheapening the cost of the zinc reduction.
A desirable plant for carrying out the above described improvement is as follows:-
reference being had to the annexed drawing in which
Figure 1 is a vertical section on the lines x-y and v-w of Figure 2.
Figure 2 is a vertical section on the lines rs and t-u of Figure 1.
The same letters of reference denote the same parts.
A Figure 2 represents a furnace for heating the ore.. It is preferably of the ordinary
reverberatory type such as is commonly used in the roasting of zinc ores.
The ore is
introduced into an upper compartment a' thence raked into a lower compartment a² and
thence when properly heated, delivered through the outlet a³ onto the chute a whence
when the bell B Figure 1 is raised it drops into the cupola C Figure 1. D represents
the furnace wherein the fuel is heated. There may be several of these furnaces as
shown at D, D, D Figures 1, 2. The fuel is introduced into the furnaces D at the
top thereof and is supplied through the openings d which may be regulated by valves
and the heated fuel is withdrawn from the furnace at its bottom d' and delivered, when
the bell B is raised into the cupola C. The ordinary means E Figure 1 as used to
raise and lower the bell which, saving when the ore and fuel are being introduced
thereinto, serves to close the cupola at its top. The reducing chamber wherein the

page_text: ore (ZO) is reduced is preferably of the cupola-type shown, the material to be treated
being received into it at its top, the slag being tapped through the usual outlot at the
bottom of the cupola, the air for maintaining the combustion of the fuel being suitably
admitted through the inlet c Figure 1 and the gases generated from burning the fuel
in the presence of the ore and at the temperature at which carbonic monoxide combines
with and reduces zinc oxide and consisting of the elements above enumerated are
discharged from the cupola into a chamber F Figure 1 containing carbon heated
as described. The chamber F is preferably an upright one adapted to receive tho
carbon at its top and having a suitable opening at its lower end for withdrawing the
ashes or whatever needs to be removed from the chamber. The gaseous current
enters the chamber F through the inlet and is discharged therefrom through the
outlet into the condenser G, Figures 1-2. The condenser is placed as near as is
practicable to the chamber F to enable the zine vapours to reach the condenser before
being reduced in temperature below the reduction point. After reaching the condenser
the zine vapour should be condensed in the quickest practicable time. To this end
and as a desirable practical construction, the condenser is made to consist of a series
of vats or flues g and separated and perhaps surrounded laterally by cooling surfaces g'.
These surfaces are produced by hollow box-like constructions through which some
cooling fluid can circulate. The zinc vapours drop through the passages 9 and are
thereby converted into liquid zinc which is suitably tapped off a gFigure 2 and the
uncondensed gases are conducted off through the outlet g³. There may be two carbon
chambers F interposed between the cupola and the condenser and the gaseous current
coming from the cupola may be sent through the chambers F alternately to which
end there are suitable branch passages controlled by valves leading to and from the
chambers F. By this means the carbon may be heating in one of the chambers F
while the other chamber is being used.
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.
First. The herein described process of manufacturing zinc, the same consisting in
pre-heating the ore and flux separately from the fuel as described, then introducing
them so heated as well as the fuel which serves to supply both the reducing agent and
the means for maintaining the reduction temperature and air for supporting com-
bustion into a reduction chamber, and therein, and at the temperature at which carbonic
monoxide reduces zinc oxide, combining the ore and carbonic monoxide and producing
zinc-vapour and then without allowing the temperature to fall transferring the zinc-
vapour directly or indirectly to a condenser and there liquefying it.
Second. The herein described process of manufacturing zinc, the same consisting in
introducing the zinc ore, fuel and flux together with air into a reduction-chamber and
therein and at the temperature at which carbonic monoxide reduces zinc oxide com-
bining the ore and carbonic monoxide and producing zinc vapour, carbonic monoxide
and carbonic acid, then conducting the zinc vapour carbonic monoxide-carbonic acid-
gaseous current into a separate chamber and into contact with carbon heated as
described therein and reducing the carbonic acid of the current to carbonic monoxide,
and then transferring the current to a condenser and liquefying the zinc and discharging
the carbonic monoxide.
HASELTINE, LAKE & Co.,
45, Southampton Buildings, London, Agents for the Applicant.