and Collecting the Metallic Zinc therefrom.
Year: 1887

page_text: HAH
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and Collecting the Metallic Zinc therefrom.
1, EDWARD WALSH, Jr., of 417 Olive Street in the city of St. Louis, State of
Missouri, United States of America, Glass Manufacturer, 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 relates to an improved mode of, and arrangement of apparatus for
reducing the oxide of zinc in native or calcined ores and of collecting the metallic
zinc therefrom in a liquid form.
Oxide of zinc is ordinarily obtained from the natural zinc ore by three processes:
The Belgian, the Silesian and the English. The former have the same general method
of accomplishing the result, and the choice between them depends upon local circum-
stances, viz. price of fuel, class of ore, and the amount of metallic zinc contained
therein; in both systems small cylindrical retorts heated externally by a Siemens gas
furnace or hand fired furnace are used, and into the retorts is charged the mixture
of calcined ores and fuel, the distilled zine being collected or condensed in the
prolongation of the retort which is firmly luted on to the end of the retort outside the
furnace. These processes are very wasteful and very laborious. Several attempts
have been made to treat zinc ores in a cupola furnace, but hitherto with little success,
practically, owing to the condition appertaining to a cupola furnace and the
temperature at which the various reactions take place not having been understood and
provided for.
My invention has for its object to overcome these difficulties and to effect the
reduction of the zinc ores as well as the condensation and collection of the metallic
zinc therefrom in a liquid form by practical and economical means in which the
conditions pertaining to a cupola furnace and the degrees of temperature at which the
various reactions take place are considered.
Zinc oxide reduces at 1300° F., and the metal distils at about 100° F., lower than
that temperature, volatilization taking place immediately on reduction of the zine
oxide. At a temperature of 1300° F., carbon is entirely unaffected by the action of
carbonic acid, and the carbonic acid generated from the reduction of the zinc oxide is

page_text: carried off with the zinc vapor at that temperature. Carbonic acid at a temperature
below 1300° F., when mixed with zinc vapor again oxidizes the latter, thereby pro-
ducing an undesirable result. But I have discovered that when zine vapor and
carbonic acid, both at a temperature of between 1400° F., and 1500° F., or slightly in
excess thereof, are allowed to pass through carbon or carbonaceous matter which is
also at a temperature of between 1400° F., and 1500° F., that the carbonic acid is
immediately converted into carbonic oxide, and that thus the zinc vapor does not
undergo any further oxidation; that the result of thus allowing carbonic acid and
zinc vapor at the temperature of between 1400° F., and 1500° F., or slightly in
excess thereof to pass through. carbon or carbonaceous matter at a like temperature
is to produce zinc vapor and carbonic oxide, and I have utilized this discovery of
the various temperatures at which these reactions take place and my knowledge of
the conditions pertaining to a cupola furnace so as to effectually reduce zinc ores
in a cupola furnace.
On the accompanying drawings Figure 1 is a sectional elevation of a cupola
furnace with its condenser and appurtenances; specially designed for carrying out
my invention; Figure 2 a sectional plan thereof, Figure 3 a sectional end view
taken on line 1, 1 in Figure 1 with top portions of the furnace removed; Figure 4
a sectional elevation of the furnace on a plane at right angles to Figure 1 and
charged with fuel and ores. Figure 5 a transverse section on an enlarged scale of
the condenser on line 2, 2 in Figure 1, Figures 6 and 7 longitudinal section and
end view respectively also on an enlarged scale of one of the outlet or discharge pipes
from the condenser, and Figures 8 and 9 modifications of Figures 1 to 4, like letters
of reference denoting like parts in all the figures.
A represents the furnace into which are charged through the hopper or shoot B the
fuel and calcined ores, mixed in such proportions that sufficient fuel is present to
effect a reduction of the zinc oxide to volatilize the zone and fuse the properly fluxed
impurities contained in the ores, these proportions being 1000 pounds of fuel to a gross
ton of ore, according to the quality of ore and fuel, and the construction of the
furnace. The mixed fuel and ores so charged are finally superadded to by fuel or
carbonaceous matter Conly through the auxiliary hoppers and shoots D. The shoot B
is so arranged that its lower end will descend into the body of the furnace A far
enough to ensure a delivery of the mixed fuel and ores at a point in the furnace A
where the temperature of the materials is at 1500° F., or slightly in excess of that
temperature and yet not so far into the furnace A as to expose the shoot B to the most
intense heat of the furnace A where its parts would be destroyed. In this shoot B
the mixed fuel and ores between the point of charging and the point of delivery are
in a state of preparation with a view of preventing the oxidation of the zinc vapor, the
moisture contained in the fuel is being expelled by the heat, and the contents of the
shoot B as it approaches the point of delivery, being gradually heated to a temperature
of about 1500° F. The same applies to the fuel contained in the auxiliary hoppers D,
the effect being that the moisture is expelled from the contents of the shoots B and D
and that the mixed fuel and ore and superadded fuel are delivered into the furnace A
in such a condition and at such a temperature that the zine vapor on its exit from the
furnace A is not oxidized.
The following is the method of operation:-The furnace A, being fired when the
mixed fuel and ore and also the overlying fuel C have reached a temperature
of 1500° F., the zinc vapor and carbonic acid (generated from the previous reduction
of the zinc oxide) from the calcined ores pass through the overylying mass of fuel or
carbonaceous matter C and in so doing the carbonic acid is immediately converted
into carbonic oxide, the effect of which is to produce zinc vapor and carbonic oxide
which pass off through a conducting tube (or tubes) to the condenser where the zinc
vapor is condensed and from which the carbonic oxide is carried off through suitable
pipes for use.
For the purpose of condensing the zinc vapor so that the zinc is deposited and
withdrawn in a liquid state and the carbonic oxide, nitrogen and other uncondensable
gases expelled, I maintain the condenser which is separate from the furnace A and may

page_text: be of any desired form and material, at a temperature of from 780° F., to somewhat
less than 1200° F., a condition which I find to be essential, for below a temperature
of 780° F., the zine would solidify, and above 1200° F. would vaporize and be expelled
from the condenser with the other gases whereas between those temperatures the gases
will be deposited in a liquid form as required.
The condenser as shown is composed of two cast iron vessels or chambers G G¹
of suitable length and preferably egg shaped transversely. They are arranged side
by side with the longest diameters of their transverse sections vertical and their
narrowest portions downwards on the floor of a flue chamber H which is formed
by brickwork I, and encloses the entire condenser. The vessels or chambers G G¹
are connected and communicate with each other through their upper and widest
portions by inverted U or syphon shaped pipes J which extend upwards into the
flue chamber H and are arranged parallel with each other at suitable distances
apart. Attached to and communicating with the vessel or chamber G through its
upper and widest portion in front of the connecting pipes J is the inlet or
induction pipe K which extends upwards or outwards through the brickwork I of
the flue chamber H to the cupola furnace A with which it communicates whilst
at the corresponding portion of the vessel or chamber G' behind the connecting pipes J
is an outlet or eduction pipe L extending upwards or outwards through the brick-
work I and either communicating with the flue or fire space M beneath the flue
chamber H or conductor to other places where the gases may be otherwise utilized.
Communicating with the lowest and narrowest portions of the vessels or
chambers G G and projecting from the ends of the latter through the brickwork I
are discharge pipes N opening at their outer ends into the external air and provided
with suitable contrivances for opening or closing their communications with the vessels
or chambers G G¹ as hereafter more particularly described.
For maintaining the condenser at a temperature of from 780° F., to 1200° F.,
I utilize the products of combustion arising from a furnace connected with the apparatus
by directing them into the flue or fire space M from which they pass through the
openings or passages O leading from the flue or fire space M where they surround the
condenser and impart a uniform temperature thereto. Or in lieu of the products of
combustion from à furnace I may use heated air from any source.
The zinc vapor, carbonic oxide and other gases passing from the cupola A through
the inlet or inducting pipes K enter the vessel or chamber G and thence circulate
through the pipes J into the vessel or chamber G' and in so doing the expansion of
the zinc vapor and the abstraction therefrom of heat by the simultaneous expansion of
its associated gases cause the condensation and precipitation of the zinc in a liquid
form to the bottom or narrowest portions of the vessels or chambers G G¹ from which
it is discharged for use through the pipes N, the carbonic oxide, nitrogen and other
associated uncondensed gases meanwhile escaping from the condenser through the
outlet pipe L either into the heating flues surrounding the condenser for utilization
in heating the latter or for other uses as desired.
For regulating the discharge of the liquid zinc from the condenser through the
pipes N, I surround the condenser end of each pipe N with a fillet or flange P having
a slot Q through its lower portion. Against the outer face of this fillet or flange P
bears a circular plate R through which is a corresponding slot or opening S the
plate R being provided with a central spindle T terminating in a handle U by which
the plate R is rotated from the outside of the open front end of the pipe N so as to
bring the slot or opening S over the slot Q for permitting the discharge of the liquid
zinc from the condenser and bringing the solid portion of the plate R over the slot Q
for shutting off the discharge of the liquid zinc from the condenser.
In the modifications seen in Figs. 8 and 9, I dispense with the central shoot B and
auxiliary hoppers and shoots D previously referred to and charge the furnace A¹ with
the mixture of fuel and ore directly through the central hopper B¹.
I also direct the conducting tubes E' upwards from the wall of the furnace A¹ and
then downwards to the condenser F in lieu of directly downwards to the latter as in
Figs. 1 to 4.

page_text: By this means the outlet for the zinc vapor and escaping gases is placed at a portion
of the furnace where the temperature exceeds 1400 degrees Fah. and as the reduction
of the ores and volatilization of the zinc take place at a temperature of 1.300 degrees
Fah. the zine vapor and carbonic acid generated are thereby made to pass through
a bed of fuel heated to a temperature of at least 1400 degrees Fah. or in excess
thereof.
Having now particularly described and ascertained the nature of my said invention
and in what manner the same is to be performed I declare that what I claim is :-
1. The method of and apparatus for reducing zinc ores in a cupola furnace consisting
firstly in charging the furnace with the mixed ore and fuel in the proportions
substantially as named, secondly charging the furnace with carbonaceous matter
independently of the other charge at one or more independent points above the mixed
fuel and ore. Thirdly, causing the carbonic acid and zinc vapor to pass through the
superincumbent layer of carbonaceous matter, and fourthly, maintaining a temperature
of about 1400° to 1500° F., in the furnace at the point to which the mixed fuel and
ore is delivered and in the superincumbent carbonaceous matter, substantially as and
for the purpose hereinbefore described and illustrated by the accompanying drawing.
2. Conducting the resultant zinc vapors and carbonic oxide from the cupola furnace
to a separate condenser for reducing zinc ores maintained at a temperature of
from 780° F., to 1200° F., substantially as and for the purpose hereinbefore
described and illustrated by the accompanying drawing.
Dated this 19th day of May 1887.