Improvements in and connected with the Extraction or Reduction of Zinc from Ores Compounds.
Year: 1889

page_text: Date of Application, 4th Dec., 1889
Complete Specification Left, 29th July, 1890-Accepted, 11th Oct., 1890
Improvements in and connected with the Extraction or Reduction of
Zinc from Ores Compounds.
I, CHARLES RABACHE of Morchain Somme 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 to be as follows:-
These improvements relate to the extraction or reduction of metallic zinc from
native ores, chemical oxydes or any other zinc containing compounds, in a single,
continuous indivisible operation, consisting in the fusion of such substances after
preliminary preparation and purification on the hearth of a specially constructed
hermetic furnace, by the action of the flameless combustion of gases, exclusive of
other fuel and atmospheric air, the combustion and combination of which gases, at the
same time producing the heat required for the fusion, and serving as re-agents for
eliminating the then remaining extraneous substances and entirely liberating the pure
metal.
Although the whole operation is unique, continuous and indivisible I will for its
easy understanding and for clearness' sake divide the whole operation into three parts
or sections.
I. The production and necessary transformation of the gases required as fuel and
re-agents and their storing into a gas holder.
II. The preliminary preparation and purification of the substances to be operated
upon, prior to firing.
III. The smelting process proper together with the recuperating apparatus of the
gases, so as to reuse them over and over again ad infinitum.
PRODUCTION AND TRANSFORMATION OF GASES.
The chemical principle of this operation is well known, but here it will take place
according to a new system or in special furnaces containing variously constructed
retorts into which proper substances are introduced so as to, in some produce carbon
dioxide gas CO2, and in the others transform the said carbon dioxide gas into carbon
monoxyde gas CO, which when so transformed, is stored in a floating compensation
gas holder of a new construction supplying the smelting furnace and other
instruments.
PRELIMINARY PREPARATION OF ZINC ORES OR OTHER ZINC COMPOUNDS.
This takes place in a series of apparatus which may differ according to the
nature of the materials to be dealt with. It consists first in breakers and crushers,
used for breaking and, crushing the raw material zine ores, and other compounds
when requisite, so as to reduce them to a granular powder of a volume not
exceeding three millimetres in diameter.. Second, In an apparatus called desiccator
into which the granular powder is introduced and the purport of which constitutes an
important feature in this new process viz.: the desiccation, disassociation and disinte-
gration of the different bodies forming the compounds, the adherence together of
which having been found to be due to the presence between them of a molecule of
water of combination or crystallisation; which water prevents their separation from
one another by any wet method. While the powder is in this instrument it is con-
tinuously shaken, heated to a temperature, variable as requisite, from 200 to 400° C.
produced by the combustion of carbon monoxyde gas CO, sufficient to vaporise the
water,. fuse, vaporise and carburate the volatile substances, such as phosphorous
sulphur &c. and eliminate them through the flue thus leaving only the metallic oxyde
with its disintegrated gangue. Third, A sifting apparatus called Volumetric Separator,
077

page_text: This
for classifying, if needed the powder in say three different bulks or volumes.
apparatus may assume different forms. And fourth an apparatus called densimétric
or ventilo separator the object of which is to separate, by means of their respective
density and a powerful blast of air, the metallic oxyde from its gangue, The mixed
disintegrated powder on being introduced into this apparatus subject at the same time
to the action of axifugal force and that of the blast of air separates. The metallic
oxyde in consequence of its superior density and weight, drops down into receivers,
whereas the gangue, owing to its relative lightness is blown off horizontally by the
blast of air. Then the dropped material is purified and reduced to pure zinc oxyde
powder, ready for the smelting furnace.
SMELTING APPARATUS.
This apparatus forms an important part of my invention. It consists in a new
system of small horizontal, hermetical furnace, terminating in a vertical gorge or
gullet, and having in its centre a syphon serving as a free and constantly opened
outlet for the fused metal. Before beginning the smelting operation the furnace must
be heated to the minimum temperature of 600° C. by the combustion of a mixture of
carbon monoxyde and air introduced by one or more tuyeres. When the necessary
temperature is attained, the powder is introduced in a continuous stream, and in small
well regulated proportions, into the furnace through the upper part of the gullet from
which it dropped down on the furnace hearth. Meanwhile the introduction of air is
suppressed and carbon monoxyde gas only is supplied. In falling, the powder meets
with an ascending current of carbon dioxide gas CO2 produced by the combustion of
carbon monoxyde and the oxygen of the air, which dioxyde, having the minimum
temperature of 600° C. communicates heat to the falling powder so that on reaching
the furnace's hearth, it is in a molten state. Directly the carbon monoxyde gas CO
introduced, combines with the oxygen contained in the zinc oxyde Zn O it burns
without flame and forms carbon dioxide CO2 which escapes through the gullet and
leaves the metal Zn entirely liberated from all extraneous substances, and consequently
pure. The reaction is as follows: Zn + CO = Zn + CO2. The metal runs off in a
continuous flow through the syphon and is by it deposited in proper receivers or
moulds.
Near its summit, the gullet is fitted with a lateral pipe which receives and
recuperates the ascending gas CO2 carbon dioxyde, and leads it to a regulating
valve from which it is sent back to the transforming retorts of Section I there to
be retransformed into carbon monoxyde CO stored again in the gas holder to be
used anew, and indefinitely as fuel and reagent, thus saving a large expense.
By the above described process, the whole quantity of zinc contained in the ore or
compounds is obtained without loss in a pure metallic state at a very much lower cost
than that of the present distilling process.
Improvements in and connected with the Extraction or Reduction of
Zinc from Ores or Compounds.
I, CHARLES RABACHE of Morchain, Somme 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:-
These improvements relate to the extraction or reduction of metallic zinc from
native ores, chemical oxides, or any other zinc-containing compounds, in a single,
continuous, indivisible operation consisting in the fusion of such substances after

page_text: preliminary preparation and purification on the hearth of a specially constructed
hermetic furnace, by the sole action of the flameless combination of gases, exclusive of
other fuel, and atmospheric air; the combustion and combination of which gases, at
the same time producing the heat required for the fusion, and serving as reagent
for eliminating the then remaining extraneous substances and entirely liberating the
pure metal.
By this new method the cost of the fusion and reduction is greatly diminished.
The invention comprises the elimination of the gangue or the principal part thereof,
water, sulphur phosphorus, acids and other waste substances from the ores or com-
pounds preliminary to smelting. It also consists in the exclusive use of pure carbon
monoxide gas in the absence of atmospheric air for fusing and reducing the ore or
compound after it has been freed from impurities. The invention also comprises the
recovery and transformation into carbon monoxide gas of the carbon dioxide gas
produced during the operation of smelting and reducing, in order that the same
may be used again and again, for the smelting and reducing or other heating
рurровее.
The methods of reducing zinc ores as heretofore for many years practised, are
known under the names of English, Silesian, and Belgian processes, every one of
which might be considered as a distilling operation, preceded by more or less
numerous and repeated calcinations or roastings the purport of which being the
elimination as far as thus obtainable, of volatile and combustible substances, sulphur,
phosphorus and other impurities existing therein and the reduction of the material to
more or less impure oxide of zine still mixed with its gangue, after which the thus
modified substances are introduced into fireclay crucibles, pipes or retorts, heated in
furnaces so as to obtain, through the action of a high temperature, the vaporization
and distillation of the pure metal, which operation, besides the time it requires
and its large expenses leaves a considerable caput mortnum causing a great loss in
metal.
Numerous processes have been tried for the purpose of separating and eliminating
the gangue and "deads" prior to distilling but so far none, I believe, have given
satisfactory results.
By the process herein described, the gangue and deads are first thoroughly
separated and eliminated from the metallic ore, so that practically only the latter is
submitted to the action of smelting heat. No coke or solid fuel is used, there is no
distillation, but only fusion. The smelting as well as the reducing is effected by pure
carbon monoxide gas alone, in the absence of atmospheric air. The carbon monoxide
gas, after having been used once, and thereby been transformed into carbon dioxide
gas, is recuperated and regenerated in suitable retorts provided for the purpose, so as
to be available for use again as fuel and reagent. This re-use over and over again of
the carbon monoxide gas, practically reduces the cost of the fuel and reducing agent
to a merely nominal sum. No flux is required; the ore being melted when in a
state of practical purity, the metal obtained is free from extraneous impurities, and
the smelting being produced solely by the combustion of the carbon monoxide gas in
the absence of air, and solely by its union with the oxygen yielded by the ore, the
metal produced is of a complete purity and requires no further operation.
The process is intended to be performed by a continued or uninterrupted series of
operations, in which the substances being heated are successively and automatically
delivered from one apparatus into another, without manual labor, and in a continuous
cycle commencing with the ore in its raw state and terminating with the perfect
metal produced. Nevertheless, if thought proper, the operations might be divided
and separated. Therefore I divide the following description into three sections.
Section I will be the preliminary preparation purification or refining of the substances
to be operated upon, before fusing. Section II will be the necessary production and
transformation of the gases required to begin operations as fuel, and as reagent for
Section III will consist in the
reducing and storing the same in a gasholder.
smelting process proper together with the recuperation of the gas, so as to be retrans-
formed and used over and over again ad infinitum,

page_text: Section I. Preliminary preparation, purification, and refining of the substances to
be operated upon.
This consists chiefly in the complete, or practically complete, elimination of the
gangue and waste material contained in the ore, and is accomplished by first reducing
the ore to a fine granular powder, and then subjecting it to a high temperature for
the purpose of evaporating the water which causes the adherence together of the
metal and the impurities which are to be separated therefrom, and for fusing
volatilizing, gasipping or burning extraneous volatile injurious substances. After
such desiccation and vaporization has been realised, the valuable portion of the ore,
the oxide, and the worthless portion are separated by means suitable for the purpose,
separation both by bulk and by density being proposed and preferred, as will be
hereinafter set forth.
These preliminary operations, of course, will differ according to the nature of the
ore or substance to be dealt with. If, for instance, it is pure zinc oxide powder it
will only require the desiccating process whereas if it is a raw ore in a rocky state it
will first require to be sorted by the hammer so as to reject the rocky barren portion,
and divide the rest into parcels of from 0.20 to 0.25 cubic centimetres ready for the
first apparatus, the breaker, which will divide it into parcels of from 0.02m to 0.03m
and deliver them into a crushing machine which will reduce them into granular
powder varying from 0.001 to 0.003m in diameter.
From this crushing apparatus the powder is delivered into a desiccator in which it
undergoes a temperature sufficiently high for first vaporizing the water of combination
or crystallisation contained in the substance and thereby dissociate, disaggregate them,
thus separating the gangue from the metallic part. Secondly, smelting, gasifying and
burning any volatile bodies, such as sulphur and phosphorus, therein contained, thus
freeing the metallic oxide, and thirdly, by the rotary shaking motion therein produced,
to disintegrate the various substances the one from the other. The desiccator delivers
the remaining modified powder, (when found necessary) into a volumetric separator
the object of which is to separate the powder into parcels of 0.001" and under 0.002™
and 0.003 in diameter, when they are ready for a last apparatus called densimetric
separator, the object of which is to separate the metallic oxide from its gangue in
consequence of their unequal density thereby eliminating the latter.
Section II. The production and transformation of gases.
The chemical principle of production of carbon dioxide gas, and of its transformation
into carbon monoxide gas, is perfectly known to chemists. Several methods can be
and are daily industrially employed which all can be applied in the present instance,
without departing from my invention. They consist in first producing carbon dioxide
gas, which can be obtained, (1) by the action of diluted sulphuric acid on carbonate
of lime or any other carbonate, (2) by the fermentation of saccharine substances such
as takes place in breweries and distilleries, (3) or by the transformation, in suitable
furnaces, of hydrated carbonate of lime into quick lime and carbon dioxide gas, and
second, to transform the carbon dioxide gas thus obtained, in carbon monoxide gas,
the means of which being equally known.
Section III. The smelting process, and recuperation of the carbon dioxide gas.
This section relates to the furnace and to the operation of therein smelting ores in a
purified pulverulent desiccated state practically free from gangue by the flameless
combustion of pure carbon monoxide gas in the presence of the purified ore and in
the absence of atmospheric air a combustion which takes place in consequence of the
combination of the carbon monoxide gas with the oxygen contained in the previously
heated ore.
Raw ores are compounds or mixtures of gangue joined to one or several metals in
different states of combination or crystallisation. Zinc ores mostly consist in three
different sorts, named calamine, blende and zincite. The first consists principally of
carbonate of zinc or oxide, mixed with gangue, water and traces of silica, manganese,
iron oxide and other matters. Blende is a combination of zinc and sulphur with
gangue with traces of iron and other matters. Zincite is an oxide of zinc joined with
small proportions of gangue and extraneous substances, the respective proportions of

page_text: Figure 1 is a longitudinal section and Figure 2 a transverse section of a pre-
paratory 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 vapors 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 shaft L which is mounted in bearings at the ends of the shell A. The
drum E is, 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
it to the discharge point J. The shell A is provided with an internal diaphragm F
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 vapors 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 he given to the revolving drum is about
9 revolutions per minute, which however may vary according to the nature of the,
The amount supplied under these conditions, will commonly be about 40 tons
per twenty four hours. Each particle of zinc ore under these circumstances is caused
ore.

page_text: to remain about 4 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 J 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.
Other forms of desiccating apparatus may be employed without departing from my
invention.
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 froin 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.
The screens may be revolving or they may be horizontal and shaking, and should
preferably be graduated to give three or more sizes. Said screens are preferably
adapted to operate upon the material as fast as the desiccator supplies it, in order
that the entire apparatus described, and to be described, may be connected to work
in a continuous manner and by automatical delivery from one machine or part of the
apparatus into another.
As a specimen of suitable screen I propose the one represented in Figures 3, 4, 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 per-
forated 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 and 2 millimeters and under in diameter. K K are arms in 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. Any
suitable apparatus for the separation of pulverulent substances of unequal density
may be employed for this purpose, and inasmuch as these machines are well known in
various arts no illustration or description is deemed necessary. I will merely state
that I prefer to employ some one of the axifugal machines with blowers or fan, as
being more reliable than those which operate by the action of air current alone or on
the common principle of aspiration.
Figure 6 is a sectional elevation of a form of apparatus that may be used. 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. F F are wings or blades of a fan the
shaft of which is rapidly rotated by a 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

page_text: gutter E and by four. holes for the passage of the screws H. C is an envelope fixed
upon the upper part of the case. D is a fan fixed on the shaft F and D¹ 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 regalate 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.
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
transformation 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 prepared 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 transformation into carbon monoxide gas. The retorts are fed, the lower com-
partments, from hoppers D containing the carbonate mixture through spouts C and
the upper ones from hoppers J containing charcoal or coke through spouts I.
inlet spout is provided with closing or regulating damper or valve E¹. Both com-
partments are provided with discharge pipes H and B for removing the ashes and
lime. L L are outlet pipes for the escape of gas. M is a smoke chimney or flue.
N is a hot air gallery round the retorts. 00 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.
Each
The
The carbonate furnace is constructed with common bricks and fire brick.
retorts are made of annular pieces of fire clay placed the one over the other,
assembled together by means of circular tennions and mortices and joined with fire
clay imortar. 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 com-
partment 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 equivalent of carbon and is thereby transformed into carbon
monoxide gas according to the chemical formula CO₂ + C. 2 CO.
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 furnace, by the com-
bination of the CO gas with the oxygen gas 0 contained in the ore according to
the reverse formula CO + 0 = CO 2 or ZnO + O Zn + CO 2.. This furnace is

page_text: 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 B at 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 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 fire-
clay 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 CO, + 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
proportion 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 cominon gas holder containing water. B is a bell
containing pipes C C¹ forming 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. D¹ 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. J is a fan taking up gas through
openings K, and forcing it into outlet pipe O, to the gasholder. P P are guides for
the bell.
A gas holder of any known system may be employed for storing the gas, but I
have devised an improved one which I name a floating compensating valveless gas
holder offering many advantages.
Figure 13 is a vertical section and Figure 14 a 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 part H of
which is made to plunge into a larger pipe I shewn more clearly in Figure 14 con-
taining water so as to prevent any leak of gas. The gas enters by the pipe K and
passes off to the pipe K¹. 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 K¹
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.

page_text: Figures 15 and 16 are vertical sections in two different profiles and Figure 17 a
plan. A is a valve regulator to determine the precise quantity of gas and air to be
introduced into the sinelting apparatus and B a pipe leading the gas to the tuyere C.
B¹, B' are pipes leading the heated gas and air into the valve regulator. The cast
iron tuyere C 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 of
the pipes, this tuyere serves as an injector for the regulated introduction of said gas
mixture, or pure gas as required, into the smelting furnace. D is a horizontal
retort, forming a crucible like hearth which at the bottom communicates with a
syphon O. a is the vertical part of a retort and 6 its first envelope made of fire clay
rings. c 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 C.O, when smelting takes place.
g is a pipe leading the carbon dioxide gas into the valve regulator E. h, k, are 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 L 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 arms K arranged
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 compart-
ment 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 are 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 numbers 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,

page_text: 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 2730° F., and second, the smelting of the
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 point 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
tuyere 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 O + C.O = Zn+C.0, 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 O which leads it
to the receiver M.
As soon as the smelting furnace commences yielding carbon dioxide gas, atmo-
spheric 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 churcoal 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
The apparatus herein described forms the subject of another patent application
dated July 29th 1890 No. 11,851 and is not specifically claimed in this specification.
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 method of treating zinc ores; which consists in releasing the metallic
part of the ore from its gangue, by the vaporization of the water of combination, and
the mechanical separation of the metal or metalloid portion of the ore thus released
from the gangue, preliminary to the operation of smelting the purified ore.
Second. The method of treating zinc ores herein described, which consists in
reducing the ore and gangue to a granular powder subjecting said powder to a high
heat, by which the water of combination is vaporized, and the volatile substances are

page_text: gasified and dispelled, and thus separating the worthless solids from the metallic part
of the ore, and finally smelting the latter.
Third. The method of smelting the ore, which consists in heating the same when
purified, to the smelting point by the combustion of carbon monoxide gas in the
presence of the ore, atmospheric air being excluded.
Fourth.. The method of reducing ores, which consists in pulverising the ore, then
raising it to a high heat (or by dropping it down a heated furnace gorge) and
subjecting it to the combustion of carbon monoxide gas, atmospheric air being
excluded.
Fifth. The method of conducting the operation of ore reduction which consists in
exposing the ore in a pulverulent condition and in a continuous regulated strain to
the heat of burning carbon, monoxide gas, atmospheric air being excluded, then
recuperating and re-transforming the carbon dioxide gas thereby produced, again into
carbon monoxide gas, and in using the regenerated gas over again in the different
smelting operations.
Sixth. The combined process for the extraction or reduction of zinc from ores or
compound substantially as described with reference to the accompanying drawings.
Dated this 10th da
T1
JENSEN & SON,
77, Chancery Lane, London, W.C., Patent Agents.