Improvements in Apparatus for the Extraction or Reduction of Zinc and other Metals from Ores or Compounds.
Year: 1890

page_text: Date of Application, 29th July, 1890-Accepted, 11th Oct.. 1890
COMPLETE SPECIFICATION.
Improvements in Apparatus for the Extraction or Reduction of Zinc
and other Metals from Ores or Compounds.
I, CHARLES RABACHE of Morchain, Sommo, in the Republic of France, Gentleman,
Honorary or Active Member of several Institutes or Scientific Societies of Europe
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 consists in apparatus especially suitable for carrying into effect the
process described in my patent application dated 4th December 1889 No. 19,501
and I shall therefore describe it with special reference thereto.
The process may be divided into the following parts viz. :-
1. The preliminary preparation, purification and refining.
2. The production and transformation of the gases.
3. The smelting process and recuperation of the carbon dioxide gas.
Figure 1 is a longitudinal section and Figure 2 a transverse section of a preparatory
apparatus.
A is a sheet iron shell which will, in practice, desirably be surrounded by sand,
B is a cover plunging into a gutter filled up by sand, and having a flue D for
the escape of vapours and gases. Within this shell is rotated a cylindrical or
slightly conical sheet metal drum E supported by suitable arms M M fixed upon a
The drum E is,
shaft which is mounted in bearings at the ends of the shell A.
at one end provided with a central opening through which the material to be
desiccated is spouted into the interior of said drum by a feed pipe H and with an
opening and pipe I, at the opposite end through which its contents are discharged.
Within and attached to the wall of the drum, are four longitudinal flanges G the
object of which is to impart, by the slow rotary motion of the drum a shaking action
to the powder, thereby facilitating the desiccating operation, and meanwhile directing
F
it to the discharge point J. The shell A is provided with an internal diaphragm
arranged to close the lateral and end spaces between the shell and the rotating drum
so as to direct the flame and burning carbon monoxide gas therein supplied through
pipe P, and cause them to pass inside of the drum and finally to escape through
flue D as indicated by arrows. The agitation of the pulverulent materials which is
going forward as the result of the rotation of the drum, exposes all parts of the
mass carried by the drum successively and repeatedly to the action of the gas flame
and heat. The heat penetrating the particles vaporizes the water therein contained
and melts vaporizes gasifies and burns the volatile bodies, such as sulphur and
phosphorus which are to be eliminated, and the vapours pass off through the flue D.
The pulverulent solids which reach the opening J fall to the bottom of the outer shell,
and escape through the subjacent spout I.
I have found that a suitable speed to be given to the revolving drum is about nine
revolutions per minute which however may vary according to the nature of the ore.
The amount supplied under these conditions, will commonly be about forty ions per
twenty-four hours. Each particle of zinc ore under these circumstances is caused to

page_text: remain about four minutes and a half inside.of the heated drum, in contact with the
flame, heat and gases produced by the combustion of the carbon monoxide gas. The
temperature of the apparatus should be kept at a minimum of 300° Centigrade
or 572° F. but may be higher if necessary.
The dimensions speed and temperature, may be varied according to circumstances,
the above named data being such as to be amply sufficient for the heat to penetrate
through all the particles, to vaporize the water of combination and to melt vaporize,
gasify and burn the greater part, if not the whole, of the existing volatile injurious
substances capable of being thus eliminated. The substances as they fall from the
opening of the drum into the spout I are thoroughly desiccated and no longer
adhere to one another, and are ready for their further and final preparation.
Preparatory to the last step or smelting operation the granular powder may if
desired be separated with respect to the volume or bulk of its particles and masses
of each size may be separately treated or the entire mass as it leaves the desiccator
may be passed directly to the smelting furnace after having undergone the following
last preparatory operation.
If before proceeding to the mechanical separation of the disaggregated substances
that pass from the desiccator, it is found desirable to size or classify the same
according to their bulk or volume, any suitable screening machine may be
employed.
As a specimen of suitable screen I propose the one represented in Figures 3. 4
and 5. Figure 3 being longitudinal vertical section and Figures 4 and 5 transverse
sections. A is an external sheet or plate iron shell enveloping the screens. C, D, E are
spaces receiving successively the different screen discharges. F is a central perforated
screen receiving the dust from a spout L. G is an intermediate screen, receiving
the screenings from the inner screen F and H is an external screen receiving the
screenings from G. The perforations of the screens are of three different diameters
the central one being the largest so that the three produce parcels of 3 & 2 millimeter
and under in diameter. KK are arms on the shaft which support the screens.
M is a driving pulley.
After separation with reference to bulk or volume; the material discharged from
the screens should be further classified or separated as regards the respective
density of its parts, metallic oxide and gangue, so as to entirely eliminate the
latter.
Figure 6 is a sectional elevation of apparatus suitable for this purpose H is a
hopper containing the powder which slowly drops from it upon the summit of a
cone C, upon which it slides down all round. FF are wings or blades of a fan
the shaft of which is rapidly rotated by pulley P. The metallic parcels D being of
greater density fall vertically down, whereas the gangue parcels which are
much lighter are blown off in a horizontal direction thereby liberating the
pure ore.
Figure 7 shews another form of densimetric separator in vertical, section. A is
an upper sheet iron plate fixed upon iron arms and having in its centre a circular
opening in the form of a funnel like truncated cone. Four screws and nuts H
connect the plate A with a lower circular sheet iron plate B placed between six upper
and six lower arms fixing it. It is concave in its centre, pierced by a circular
gutter E and by four holes for the passage of the screws H, is an envelope fixed
upon the upper part of the case. D is a fan fixed on the shaft F, and D' is a hopper
serving as aspirator to the fan, and receiving the dust from a spout D" which
supplies the mineral dust coming from the volumetric classifier. E is a circular
gutter into which drop the densest parcels falling into a casing O. G is a pulley
for rotating the shaft with the two plates A and B and the fan D. The screws H
serve as guides to separate as required the two plates A and B and regulate the
apparatus according to the nature of the material to be treated.
K is the space
between the two plates. L L are iron radial arms. M M are internal sheet iron
divisions. N is an outer enveloping casing.

page_text: PRODUCTION OF CARBON DIOXIDE GAS, ITS TRANSFORMATION INTO CARBON, MONOXIDE
GAS AND THE STORING OF THE LATTER INTO A GAS HOLDER TO BE USED IN THE
WHOLE OPERATION.
The mode of producing carbon dioxide gas is well known as well as that of its trans-
formation into carbon monoxide gas as before said but in the present instance and in
case it should be found proper to produce or extract the carbon dioxide gas from
suitable carbonate I will here describe a new apparatus which gives most satisfactory
results. It is illustrated by Figures 8 and 9 which represent in vertical section and
in plan section on line X X two vertical cylindrical retorts 1 and 2 destined to receive
a mixture of carbonate of lime, or other preferred carbonate and crushed coal or coke
for first transforming such carbonate into lime and carbon dioxide gas. To that end,
said retorts are divided into two compartments by a horizontal fireproof grate F. The
lower compartments A A receive the carbonate and coal or coke mixture and the
upper compartments receive charcoal or coke rendered incandescent through which
the vapours and gas produced in the lower compartments pass for their trans-
formation into carbon monoxide gas. The retorts are fed, the lower compartments
from hoppers D containing the carbonate mixture through spouts and the upper
ones from hoppers J containing charcoal or coke through spouts I. Each inlet spout
is provided with closing or regulating damper or valve E. Both compartments are
provided with discharge pipes H and B for removing the ashes and lime. L L are
outlet pipes for the escape of gas M1 is a smoke chimney or flue N is a hot air gallery
round the retorts OO fire brick work P common brick work. S is the fire place
and grate. T tank filled with water to receive cinders. U is a casting for dividing
the flame. V is a slide for opening or shutting at will the communication between
the hoppers.
The carbonate furnace is constructed with common bricks and fire brick. The
retorts are made of annular pieces of fire clay placed the one over the other
assembled together by means of circular temnons and mortices and joined with fire
clay mortar.
The double hopper D is of a capacity to contain a ton of carbonate and 6 cwts. of
small coke mixed together. In front of the upper tube of the retort is a safety pipe
terminating at its upper end by a light valve, which should open in case of the grate
bars becoming choked and the passage of gas into the upper compartment becoming
obstructed. The charge of charcoal or coke is about 25 or 26 inches high. The
retorts are say nearly ten feet high inside measurement and say 3 feet in diameter.
By these contrivances the carbon dioxide gas produced in the lower compartment
passes up into the upper compartment filled with charcoal or coke in which it takes
hold of one or more equivalents of carbon, and is thereby transformed into carbon
monoxide gas according to the chemical formula C.0, +0=200.
=
Figures 10 and 11 are vertical section and plan section views which illustrate the
furnace containing the retorts for retransforming into carbon monoxide gas the carbon
dioxide gas produced in and recuperated from the smelting furnaco, by the com-
bination of the C.O gas with the oxygen gas O contained in the ore according to the
reverse formula CO + 0 = CO, or Zn + 0 =
Zn + CO₂.
This furnace is
intended to contain eight retorts A A (a number which may vary ad libitum) designed
to receive the carbon dioxide gas produced in the smelting furnace hereinafter
described, and to transform such gas into carbon monoxide gas. These eight retorts
provided with grates near their lower end, are by means of hoppers D D charged
with charcoal or coke rendered incandescent and are provided with proper connecting
coronal and inlet feeding pipes E at their lower part, and coronal outlet connecting
discharge pipes Bat their upper part. The furnace is constructed of a first enveloping
internal circular wall G in fire brick separated from a sheet iron external cylindrical
casing H by a space I say about 4 inches wide filled up with heat non-conducting

page_text: material. Inside of this wall are placed the eight transforming retorts A isolated
from each other so as to receive the full action of heat all round their external surface
from the gallery K that surrounds them. The eight retorts are made of fireclay or if
thought proper of cast iron or other suitable material. When charged with charcoal
or coke, they receive in their lower part under the grate from the coronal feeding
pipe E a supply of carbon dioxide gas coming from the smelting furnace which gas is
to be retransformed into carbon monoxide gas by taking up in its passage through the
incandescent charcoal or coke one equivalent of carbon according to the already
mentioned formula CO₂ + C = 2 CO which transformed gas escapes through the
upper outlet and coronal pipes B to be taken up by the exhauster hereafter described
and stored in a gas holder ready for re-use. The furnace is heated by means of gas
introduced in the combustion chamber and its divisions M P. The feeding hoppers D D
must be kept hermetically closed to avoid the escape of gas.
The regenerating retorts will be kept at a temperature of about 2000° F. minimum
by means of the requisite amount of mixed gas and air supplied in the combustion
chamber. The number and dimensions of such furnace and retorts should be in pro-
portion to the work required. The gas obtained by this transformation costs still less
than that originally produced in the carbonate retort.
The exhauster and regulator is shewn at the vertical section Figure 12 A is a
receiver in the form of a small common gas holder, containing water. B is a bell
containing pipes CO₁forming the inlet and outlet for gas. D is a rod supporting
the bell B and serving as a guide in the rising and lowering of same.
D' is a
plate separating the upper part of bell B into two sections so that, when lowered
the communication is intercepted. E is a lever fixed to a pinion G and sliding
between pulleys F. F, M is a valve moved automatically by its rack H gearing
with the pinion G, by the fall or rise of the bell B. Jis a fan taking up gas
through openings K, and forcing it into outlet pipe O, to the gasholder P Pare
guides for the bell.
A gas holder of any known system may be employed for storing the gas, but
I have devised and improved one which I name a floating compensating valveless
gas holder, offering many advantages. Figure 13 is a vertical section and Figure 14
à detail view of such a gasholder. It consists of an ordinary gas holder basin,
built in brickwork N and a floating sheet iron bell A both of cylindrical form.
The bell A terminates, at its lower part, in an annular case or air chamber B
hermetically closed the object of which is to contain a sufficient quantity of air
to form a counterpoise to the total weight of the bell and its accessories which by
this means, will float on the water contained in the. basin N. The gas inlet and
outlet pipes are formed of two bent limbs G. H one pari H of which is made to
plunge into a larger pipe I shewn more clearly in Figure 14 containing water so
as to prevent any lack of gas. The gas enters by the pipe K and passes off to
the pipe K. This gas holder receives the gas as supplied by the exhauster, stores
it, and delivers it as required, either for the smelting furnace or for any other
heating purposes, by means of the above mentioned outlet pipe K' fitted with all
required valves and cocks. The capacity of the gas holder is not limited but here
is fixed to about 3000 cubic feet, a capacity which will amply suffice for holding
such a store of gas as will be needed for the smelting of 20 tons of metal in
24 hours.
SECTION III.
Figs. 15 and 16 are vertical sections in two different profiles and Fig. 17 a plan.
A is a valve regulator to determine the precise quantity of gas and air to be
introduced into the smelting apparains and B a pipe leading the gas to the tuyere ().
B, B', are pipes leading the heated gas and air into the valve regulator. The cast
iron tuyere is divided in three compartments, two of which lead air when firing
the furnace and the third receiving the gas from the gasholder. By proper form

page_text: of the pipes, this tuyere serves as an injector for the regulated introduction of said
Dis a horizontal
gas mixture, or pure gas as required, into the smelting furnace.
retort, forming a crucible like hearth which at the bottom communicates with a
syphon O. a is the vertical part of a retort and its first envelope made of fire
clay rings. is its second envelope made of fire clay bricks. d is an annular space
to be filled with heat non-conducting substances and e a sheet iron casing enveloping
the whole. is an escape pipe for smoke or gas CO, when smelting takes
place. is a pipe leading the carbon dioxide gas into the valve regulator E.
k, kare the pipes of the valve regulator. Fig. 16 is a sight hole fitted with glass
permitting to look inside the furnace. The valve regulator E has a cone valve F
for regulating the passage of the carbon dioxide gas from the smelting furnace to the
transforming retorts. K is a colander, or apparatus to distribute the powder, into
the gullet or gorge of the retort furnace, and L an elevator for the powder. M. is a
pan for receiving the molten metal and N the pipes for the carbon monoxide. The
molten metal runs off through the syphon O into the receiver M in a continuous
manner as soon as melted and before it has time to re-oxydize. The syphon and
receiver must be in infusible material and set in a manner as to be properly
heated from their outer surface. The receiver is provided with a cover with an
escape pipe m for gases or vapors that may exist therein. The furnace flue, gullet
or gorge is hermetically closed at the top by a metal case into which the pulverulent
desiccated material is delivered through a spout provided with a valve and to which
it is elevated by any suitable apparatus, as, for example by the endless chain bucket
elevator I shewn here. Through the top of the case extends down a spindle provided
at its lower end within the case with a series of diverging colander cams Karranged
in the path of the pulverulent material falling from the spout, and adapted by their
revolution to disperse them in their fall into the gullet. The spindle is suitably
driven as for example by bevel gearing indicated on top. The pipe f of about same
diameter as the gullet, carrying the carbon dioxide gas produced by the combustion
of the carbon monoxide gas with the oxygen supplied by the ore in the smelting
furnace bends downwards and then upwards, and terminates above the water line
in the trough or box of the hydraulic regulating valve E shown in Fig. 15 and
within one compartment of the divided bell of this valve. From within the other
compartment of same bell passes a second pipe fitted with a regulating graduated
conical valve F which leads to the regenerating retorts already described, and
whence its contents are taken into said retorts by the coronal inlet pipes. The
hydraulic valve bell is adapted to be raised and lowered by any suitable means,
one familiar form of which is shewn. The hydraulic furnace regulating valve
serves not only to control the draft of the furnace and the passage of the gas
therefrom, but also to condense any volatile substances that may remain in the gas.
The gas and air sent to the tuyere to be introduced therefrom, into the smelting
chamber, are previously heated to about 570° F. in their passage through the
pipes N, N, which to this end are conducted through the brickwork of the furnace
in any desirable manner, and said pipes re provided with all needful valves and cocks
not necessary here to be pointed out.
The following dimensions of the furnace, will be in proportion to the previously
described members of the apparatus adapted to operate upon about 40 tons of ore
in 24 hours. The furnace will be about 20 inches wide inside. This vertical
gullet, gorge or flue, is composed of superposed annular blocks of mixed fire clay,
fire sand and graphite amalgamated with a small quantity of asbestos. Around
these annular blocks is a body of brickwork and between the brickwork and an
external sheet iron shell is a body of sand. The horizontal portion of the furnace
is lined with fire bricks and the hearth is faced with a hard rammed mixture of
fire clay, fire sand and grit or graphite amalgamated with asbestos like that forming
the interior wall of the gorge.
The smelting operation comprises, first, the firing of the furnace and the heating
of the same up to a temperature of about 2780° F., and second, the smelting of the

page_text: metal contained in the ore, by the flameless combustion of the carbon monoxide
gas with the oxygen of the ore, in the absence of atmospheric air. The heating
of the smelting furnace requires from 4 to 5 hours to bring it up to the smelting
point, before the smelting operation begins. When the suitable temperature has
been reached, the dispersing colander K at the top of the furnace gorge is set in
motion and the pulverulent ore is introduced, while the introduction of atmospheric
air through the fuyere C, is suppressed. In dropping the powder it meets with
resistance from the ascending current of gas resulting from the combustion of the
carbon monoxide gas in the furnace, and in consequence of such resistance it will
accomplish its fall slowly and when it reaches the hearth it will have arrived at a
suitable temperature.
===
As soon as the purified powdered ore has fallen to the bend at the bottom of the
gorge, it is enveloped by the carbon monoxide gas forced into the furnace through
the tuyere, air being then excluded, and the absorption of the molecules of oxygen
in the molten ore takes place as a result of their combination with those of the
carbon monoxide gas, giving rise in this instance to the reaction expressed in the
formula Zn 0+00: Zn + CO2, which liberates one equivalent of zinc to one of carbon
monoxide gas, by forming one equivalent of carbon dioxide gas. The reaction taking
place in the absence of atmospheric air, produces a flameless combustion which gives
rise to a temperature exceeding 4350° F., which is more than sufficient for the purpose.
The metal thus set free, runs into the depression or crucible in the smelting chamber
of the hearth together with the "deads" should any remain floating on the surface of
the molten mass in the shape of slag. This reduction being effected by the agency
of the gas alone without any intervention of air, prevents the injurious effects which
would be produced by the nitrogen of the atmosphere. As soon as smelted and freed,
the pure metal runs off in a continuous stream through the syphon ◇ which leads it
to the receiver M.
As soon as the smelting furnace commences yielding carbon dioxide gas, atmospheric
air being excluded, the produced gas, on being directed to the transforming retorts, is
by them transformed again into carbon monoxide gas, and delivered to the gasholder
which supplies the smelting furnace and other apparatus. At that moment the smelting
cycle is complete and the smelting operation is continuous. The ore, therefore is
smelted at the cost merely of the charcoal or coke used in the conversion of the carbon
dioxide gas into carbon monoxide gas. Inasmuch as the fuel is applied only to the
purified ore, the cost, for fuel, per ton of the product in the method herein described
is exceedingly small.
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 ;-
For the extraction or reduction of zinc and other metals from ores or compounds :
First. An apparatus for preliminary preparation, purification or refining of metallic
zinc and other ores, consisting of a casing provided with sand-luted cover or closed
against the entry of air, a rotatable drum arranged within the casing and into one end
of which the ore to be treated is fed and through which it is conveyed being exposed
therein to a shaking action by slanting internal ledges or equivalent appliance, a
perforated pipe or pipes for carbon monoxide to issue upon the drum and to enter the
same at the ore feed end to act upon the ore for vaporizing the water of crystallisation,
and fusing melting, gasifying or burning the sulphur, phosphorus and other volatile
substances, and to issue at the other end and pass off by an exit flue at the ore feed
end of the casing while the treated ore passes off by an exit at the other end of same,
substantially as set forth.
Second. An apparatus for separating or screening according to bulk or volume
metallic zinc or other metallic substances consisting of two or more rotatable screens
mounted upon the same shaft one within the other and having perforations of different
gauge, three or more spaces for securing the screenings, one being at the feed end to
receive material from the annular space between the innermost screen and the next

page_text: outer screen, another at the opposite end to receive material from the innermost screen,
and one intermediate one below the screens the whole being arranged in an enclosing
case, substantially as set forth.
Third. A densimetric separator for separating powdered metallic zinc or other
metallic substances into their constituent parts of unequal density consisting of a cone
dise upon which the material descends from a hopper at the apex, and a fan arranged
below the cone on a vertical axis whereby the heavier particles drop more or less
vertically while the lighter ones are blown away laterally, substantially as set forth.
Fourth. A densimetric separator for separating powdered metallic zinc or other
metallic substances of unequal density consisting of two plates fixed on the same
vertical rotatable spindle at an adjustable distance apart the upper plate having a
funnel wherein is a fan fixed on the same spindle and into which the powder is drawn
from a feed pipe, the lower plate being concave in the middle and provided with lower
annular outlet to an inner compartment for receiving the heavier particles while the
lighter ones pass out between the plates.into another compartment, the whole being
enclosed in a casing substantially as set forth.
Fifth. An apparatus for producing carbon dioxide gas consisting of a fire brick lined
chamber containing one or more upright retorts divided by a fire grate cross partition
and heated from a fire below, the lower compartment receiving the carbonate and coal
or coke mixture; and the upper compartment receiving the charcoal or coke, rendered
incandescent and having upper outlet for the carbon monoxide formed by the vapours
and carbon dioxide gas from the lower, compartment passing through it both compart-
ments being provided with upper feeding hoppers and lower waste discharge openings
substantially as set forth.
Sixth. An apparatus for transforming carbon dioxide gas into carbon monoxide gas
consisting of a fire brick lined chamber containing a series of upright retorts connected
at the top to a common carbon monoxide outlet pipe connected at the bottom to a
common carbon dioxide inlet pipe, the retorts having hermetically closed upper hoppers
for supply of coke or charcoal and being heated by a gas fire from below, substantially
as set forth.
Seventh. A gas exhauster and regulator consisting of a gas holder tank containing
water and a bell luted thereby and having a partition which when the bell is descending
shuts off the communication between the inlet and outlet pipes which rise therein the
latter pipe communicating with a box containing the exhausting fan by a valve which
is regulated by a connection to the bell, so that in the rise and fall of the latter the
valve is opened or closed substantially as set forth.
Eighth. A floating compensating valveless gas holder, consisting of a gasholder
tank containing water and a bell luted thereby and having a lower annular closed air
chamber, said bell being provided with syphon shaped inlet and outlet pipes the lower
limb of each being adapted to work up and down in a cylinder containing luting water
and around an inner pipe such inner pipes connecting respectively one with the gas
pipe from the exhauster and the other with the gas pipe to the furnace substantially
as set forth.
Ninth. A smelting furnace consisting of a suitably lined hearth provided with means
for admitting a regulated quantity of gas or gas and air thereto and with syphon
outlet to a receptacle for receiving the molten metal before it has time to re-oxidize
and of a furnace shaft or retort rising from the hearth made with fire resisting and
heat non-conducting material and provided with a colander or feed apparatus at the
hermetically closed top and with exit flue to a valvular draught regulator for conducting
the carbon dioxide gas to an apparatus for transforming it into carbon monoxide
substantially as set forth.
Tenth. The several constructions of apparatus shewn in the drawings.
of July 1890.
JENSEN & SON,
77, Chancery Lane, London, W.C., Patent Agents.