US1080912A - Method of electrically smelting volatile metals. - Google Patents

Description

W. MQAJOHNSON. METHOD OF ELEGIRIGALLY SMEL'IING VOLATILE METALS.

APPLICATION FILED JAN.17.1911.

Patented Dec. 9, 1913.

3 SHEETS-SHEET 1.

W. MOA. JOHNSON. METHOD OF ELEGTRIGALLY SMELTING VOLATI LE METALS.

APPLICATION FILED JAN. 17.1911.

Patented Dec. 9

8 SHEETS-SHEET 2.

WITNESSES W. MOA. JOHNSON.

METHOD OF ELBGTRIGALLY SMELTING VOLATILE METALS.

APPLICATION FILED JAN.1'7,1911.

1,080,912, Patented Dec. 9, 1913.

3 SHEETS-SHEET 3.

wooLsnYMoA. Jonrrsoir, or HARTFU-Rl-D, CGNNEGTICUT.

METHOD OF ELECTRICALLY SMELTING VOLATILE METALS.

l Specification of Letters Patent. 'a iaiemun inea January 17, 1911.

'Ezrtentcd Dec. 1913. Serial No. 603.

To all whom it may concern."

Be it known that I, Wonsnr MoA. JoHN- soN, a citizen of the United States, at Hartford, in the county of Hartford and State of Connecticut, have inventedcertaln new and useful Improvements in Methods ofEleeIrically Smelt-lug Volatile Meta-ls, of which the following is a full, clear, and exact description, such as will enable others skilled in the art to which it appertalns to make and use the same.

This invention deals with certain improve- 'ments in the art of obtaining from their ores. or compounda metals volatilizmg at their smelting temperatures, but inasmuch as certain notewortfif characteristics ofthe' invention prominent appeal" in its more intense aspect as amethod of reducing and separating zinc 'by a volatilizing process in I which, through tl1e, instru1nentality of an electric furnace, thcvapors of zinc, together 'with pcr-tions of the charge, are advantageously utilized as conductors of an electric; current; it will he conducive to clearnessc to.

specifically, disclose this invention by m of such embodiment thereof.

Newt-his invention has in contemplation the formulation of an essentially commercial method of deriving metallic zinc from its ores or compounds through the instrumen tfality of 'alnelectric furnace. and it seeks so. to devise and coordinate the several steps ofthis process .that each step will'not only specific purpose, but also will harmonize and cooperate with the other slcns'i-n enhancing the. general elliciency of the complete method.

Another and further object is to render commercially available complete zincsuielting process capable of a continuous o ieration in the treatment nilarge quantities of varied classesfof Zinc ores With a small labor charge, at a high thermal efiiciency. with a-low cost of repairs and requiring ,the investment of only a moderate amount of capitahand' which will be capahle of yielding directly merchantableproducts and by-proclucts such the specific treatment of zinc-bearing ores.

drawings exemplifying a preferred embodiresiding I as outlined in my ores relatively torexample. may he pure s elter; 1 lead-copper matte, base lead bullion; and

7 jriim about 40" high'i .m. be elcctricallyhcatcd' ment of a preferred means instriunental in carrying out certain steps of this process havebeen appended as a part of this disclosure, and in such drawings like characters of reference denote correspondmg throughout the several views, of which,

Figure l is a top plan View of an elec tric furnace'such as- I contemplate using, preferably in connection with sulfur-hearing ores of zinc which have first been treated UnitedStates Patent No. 868,345; Fig. 2 is a longitudinal verticalsection taken through said-furnace showing the hoppers in section and omitting certain parts for clearness; and Fig. 3 is a vertical transverse section taken along line 3-3 of Fig. 1 looking toward the left hand.side thereof.

Continuing now by way of a detailed (lescription of the method proposed in accordance with my invention. it will be conven rent to describe the structural details of this apparatus while tracing the pursued in carrying cially. as applied to successive steps out my method esperich in iron and sulfur. Turning now to the drawings. A indicates afurpace body which"conveniently may he rectangular in contour and he formed of refractory material. such as fire brick. built to form abuse portion or botloni l. a front.

wall 2'. a rear wall 3. two end walls 4 and the tone. Preferably. the latt'euwill also he made u p of tire bric s i"- placerl together in the town of an arch to form a strongly constructed roof for the furnace. in order to further enhance the strength of the fur- .nace body. an outer layer 7 of concrete surrounding the uprising walls may be used, and furthermore suitable stays. heavy angle irons. tie rods and the nloyed tostron zly bind the whole into a eel? contained and mechanically strong structure.

The construction above described provides an inclosed substantially air-tight chamber which may vary in dimensions but 'which, 307 by 60,". and higl enough to enable itcoutain a charge col- 'hich the charge is tit of contact with ill(3.'{1lI and the instrurne'ntality for sohoatihg consists of suitablv arranged electrodes me or more of Whirl are depending and another of which may hearranged to lead in, at or near'the bottom oi'. her. Thus, electrode 8 which, for iiithe treatment of zine like. may alsobe erniii! the furnace chamstance, may be made of two copper bars 1} by 4;", or may be constructed of other suitable material, such as graphite, carbon, or iron, leads through the walls of the furnace and extends toward or near the bottom surface thereof so as to expose a sufficient surface to afford an opportunity for the easy mssage of the electric curre'ht. Inasmuch as during the normal operation of the furnace, a layer of molten materialof extremely high electrical conductivity, such as lead, iron or fusible sulfid, accumulates in the hearth of the furnace, such electrode tends to heat considerably and by reason of the resultant expansion, tends to loosen the joint between such electrode and the material of the furnace body and thus possibly enable this molten material to run out and escape from the furnace. To obviatethis, I propose to surround or arrange adjacent portions of the electrode, a cooling means such as the coiled pipe 9, through which thus maintain a' tight joint in the parts.

In the drawings, I have also. shown a pair of depending carbon or raphitc electrodes 10 and 1 1, but-it is to .e noted that this invention in thisresp'cct is subjectto some modification. These electrodes are preferably constructed of some enduring material, such as graphite, capable of conveying I large currents. For example, the two u per chain 130i thebloc electrodes can be made 6" square, an

position up and down. To this end, l. recommend tiat the-upper ends of said graphiteelectrodes be placed within a contact block 12 which is sus ended by means of the and falls. Owin to thefact that these electrodes are exce ent conductors-of heat and thus tend to become highly heated at their u per ends, and in turn overheat the meta 10. connections, I provide the blocks 12 with one or more interior channels 14 through which cooling water is ,circulated by means 'of suitable flexible connections as with rubber hose, as indicated. This simple construction suitably carries the weight of the electrodes and. at the same time enables the o orator to very easily and rapidly adjust t e relation between these e lectrodcs and the bath of slag. The arch of the electric furnace is preferably provided with an aperture for eachelectr de, pieferably having downwardly converging sides, shown by 15. A packing of asbestos 16 forms a simple yet effective gas-tight joint and at the same time does not interfere with the adjustment of such electrodes.

The electrodes may be connectedin varh' ous ways, depending upon the character of the ore and reducing agent, and on the volt age tbatthe power plant can most con lellltlll ly deliver. Thus they may be connected in series so that tl upper electrodes as the neutral conductor.

water may be circulated to absorb all excessive heat and so- 'mounted as to permit of being adjusted in 35' on the hearth of the'furnace will act as an intermediate electrode for receiving the current passing downwardlyfrom one of the I and for delivcrin; such current upwardly to the companion electrode. placed so as to form an equilateral triangle connecting with a three-phase current, in which case the molten electrode will serve But the improved form of connection, and the one which posscsses social advantages and is mostpreferred or practical purposes, is that shown by the drawings. in which all of the upper uprising electrodes are connected only to one bus-bar of the generator or transformer and the lower electrode is conl'iectcd to the other bus-bar. The furnace is most advan- Or the upper electrodes may be tageousl operated by an electrical appara tus capa le of furnishing ower at a con stant amperage, and thus eit 'icr direct, single phase or polyphase current can be employed. The voltage suitable for my process can conveniently be 110 and the amperage 4500, and a good practical rule is to employ about 600 ampcres per square foot of smelting zone to bsorb 80 per-cent. of the net electric energy cent. in the slag bath, and about 2 per cent.

in the carbonaceous filter, which will be shortly described.

The crucible of the furnace is first charged with pig lead in such quantity to form, when melted, the load pool. Then the furnace may be started in various ways within the ordinary slrill of the art, as, for example, by preliminarily pouring hot metal or hot slag intothe same, or by simply striking an arc by contacting the electrodes with a coke covering carried by the lower electrode. and gradually raisingit as the slag melts, or a certain amount of slagmay be placed in the furnam and the latter then heated by building aiwood or coke, fire in the same and by utilizing theelectric current, as may be desired. i

Before commencing the regular charging for the continuous smelting operation, I pro pose that the furnace aud ts contents be thoroughly heated up to avoid untoward condensations of the metal. In this preliminary hcating run, the furnace is charged at intervals with old sla or with a. slag-makin charge. It is advisa do that this slag sha contain no Zinc or other volatile element of a nature capable of subsequently condensing to clog up the outlet pipes of the furnace or to accumulate in the condenser. After eight to ten ours of prolonged heating, using something like an average of 200 kQw. on a furnace of 500 it. w. rating, the slag will be. heated to 1300 to 1350 degrees (1, and the.

irectly in the smelting zone, about 18 per I e molten electrode 1 and by the heat deducted and radiated from 129 the furnace chamber. When these condi-' tions have been attained, the charging pipes are opened and a charge of zinc ore mixed 'with'fine coke or coal and. heated to a temperature somewhat above the melting point ofzinc, z. 6., above 415 C. This charging may take place through one or more charging funnels 17, which may be constructed pf fire clay and luted through the arched roof so as to terminate within the same a-short distazice below said roof. These funnels may be arranged in different locations in the roof, but preferably they are disposed adjacent the forward wall of the same as a matter of convenience in adding charge thereto; the constructin shown, the funnels 17 are maintained in a heated condition byt-he hot vapors in the upper part of the furnace, and they may. be jacketed above their entrance into the furnace by a reheating device.

It is important, cit er by introducing the charge in a sufficiently. heated. state, or by heating the funnels,'t-hat the column in such funnels be kept hot enough to enable it to feed properly. In initial runs, when the operators are unusedto the operation, it is well to measure the temperature of the first charges by one or more pyrometers 27 dispose somewhat as shown in the drawings, for if the charge be cold-and the reduction o'lZnO and the evolution of zinc vapor'and carbon monoxid be rapid, the charge in'the smelting chamber and in the charging pipes ,will condense zinc in their upper portions so as to disseminate through the charge the zinc as a solid metal in the form of frozen drops. This act-ion will cause a scaffold to form which will later be melted out by the g bath which will suddenly drop the cold charge on the heated slag and possibly cause an explosion, depending on the severity of ,such untoward conditions.

Under normal working; conditions I pro pose that the distance between the slag and the bottom of the overlyiigg'eleetrtxies shallbe'a'hout 8 to 10 inches hereby put into practical elfect my discovery that this is not only metallurgioally advantageous, but also con'nnercia-lly feasible by reason of= the conductivity of the disseminated iron and the zinc vapor present in the smelting zone, the conductivity of" which is marked and appreciable atthe temperature existing in the tie til.

,. proposes as a smelting; zone, i. new '6.

In the case of one. s peoific type of ore which a, some degrees above 'my process is adapted to handle with peculiar advantage, sulfids of zinc, lead and iron are concomitantly present in material quantities. ln such case, this invention preliminary step in the processthe external preparation of such ore in accordance -with the plan outlined in my United States Patent No, 868,345, granted October 15, 1907, in accordance with which continuously ancewheel.

such oxide or compounds as PbO, Fe,0 and FeO .(SiO,,).z, etc., are formed from the sulfids by an outside carefully conducted roasting operation, and said compounds 1educedby carbonaceous material in an exterior furnace, heated charge will contain from to 25 per cent. of sponge iron. this step is to obtain a starting material in which further reactions and reductions can take place in a continuous way in the electric furnace. In any event the charge isintroduced into the electric furnace as rapidly as smelted.

Assuming that the furnace has been brought into a condition of normal operation, its contents willordinarily be as ref;- resented by the drawings, in which 18 in cates a bath or lowermost layer of lead in a molten ciondition lli indicates an overlying layer of'matte, and 20- represents a considerable body of fluid slag. ()rdina-rily the lead pool will be about 2 to 3 deep and preferahly'a lead well shown by 23 isluted through thefurnace wall, which is-provided with a recess. 24 underlying the lea'd well to heat or cool the latter; A tap 26 enables the slag to be run out, and an underlying tap enables a proper amount of matte to be maintained, say from 4" to 8 deep. These taps may be water-cooled and disposed according to circumstances and may serve to drain the furnace whenever this is desirable. The mass of slag is of. considerable advantage'inasmuch as it serves in the capacity of a thermal. balance whee], so towspeak, and furthermore, may be utilized for the generation of additional heat in the electric furnace by reason of its resistance to the passage of the electric current. The sla bat-h acts also as an emergency rheostat anc gives a definite fixed minimum internal so that the preparedand pre- The purpose of resistance to-th'e furnace that prevents shortcircuit-in by exaggerated arcing through the zinc vapor. Vhile in. normal operation it works as a thermal balance wheel, in periods of need it acts as an electrical bal- The charge 21 will occupy a large portion of the furnace chamber, as shown by the drawings, and-between it and the upper surface of the bath-of slag a layer, rich in carbon, such'as coke 22, may be When the electric current through the electrodes, will be partly absorbed 20 and partly in the smelting zone. In said smelting-zone the current is conducted partly through somesolid contacting portions of the charge. and partly also through the zinc vapor which is present and which is utilized in part as a carrier for the current.

As the'slagbath plays a peculiar'part in my process, it is perhaps advisable to ami is passed its electrical energy by-the bath of slagplify its purpose and its characteristic re lation to other parts of the process, to aercutuatc to those skilled in the art the in--' tcrdepcndence of the various steps of my process and the manner in which they pro-f 5 mole a smooth and controllable smelting by mutually acting m an automatic compensate in capacity. This slag bath operates as means instrumental in carrying'out that partof my process whereby about 18-to 20 per cent. of the total amount of electrical energy is directly and specifically absorbed and transformed by resistance into heat so that as its temperature increases ,by any means, the heat thrown upward also increases, and as the heat internally gainedby the slag bathv decreases, its reslstance decreases. Thus, as the furnace is operated on constant amperage the voltage of the fur the total energy is absorbed by the slag bath, and accordingly a nearly constant flow of heat keeps the smelting zone at the proper temperature for the smelting. The

heat of anyintense and momentary local} nace decreases and a smaller proportion of heating of the smelting zone is absorbed.

by slag-bath. Its great latent heat com bined with the cooling effect of the descends lug charge which has great heat require ments keeps heat supplied to the smelting zone in such degree as to keep the smelting zone at +1033 (3., should the temperature there fall below this smelting temperature, and thus the smelting conditions are kept uniform.

The is most. advantageously 'made of a lime iron-oxid scsquisilicate with not over 12 per cent. Al O and to increasefluidity l' may incorporate in the charge from 5 to '10 per cent. of floor-spar. This, however, is

not essential. I advise the operation of the furnmze be such that the slag kept about 100 degrees C. above its running temper.- tnrc. This is easily effected by the. per" :t

control over temperature that my electr0-' thermic sniclting'proccss allows. 'lhe slag bath continually absorbs the mineral components of the charge in a manner exactly similar the role of slag in a lead or iron blast-furnace.

The foregoing general and detailed description of the functions of the slag: bath always must. be kept in mind in connection zone percolate upward through the descending charge, thereby heating it, and

few degrees above 862 C. (Richards lllctallurgical Calculations, Part III, page {322, shows thisto-bc minimum temperature at which equal volumes of Zn and CO can coexist in gaseous state under 760 min. pressure), and passfrom the top of the charge jcolumn, through the, cductor to the coni'dcuser. The charge scltlcs downward. rcg- Zularly, being replenished by the fall of fresh charge from the feed pipes to the furnace chamber. I

Such is the general smelting operation. To enable one skilled in the art to gain a chemical details of the smelting zone, let us consider the course of a small cube of hire of +415 C. As such an element dc scen ds, itieomes continuously in contact with the gases of. reduction ever growing hotter as the elcment'progresses toward the smelting zone and its temperature isra-ised to the temperature at. which the charge is conductive. This critical smelling temperature is about 950 (1. As soon as the element attains this critical smelting temperature, it has reached, of necessity, the smelting zone. Here the current density of the element increases from zero to an appreciable figure and the electrothermic result'is that the element rapidly assumes the reduction tempcrature for zinc oxid, e., +1033 C. Inunediatcly thereafter the current density through the element of charge again increases for the zinc vapor a utogenmisly gen- ,erated acts as gaseous conductor. The iam- -porature would rise very quickly much above 1033" C. were it not for the great .hcat-absorbimc capacity of the charge, for the reaction ZnO+C=Zn+CO is strongly endothermic and in the caseof pure hot materials with hot products it absorbs per cal. l, page 50).

As a natural result, the reduction proceeds actively and its rate is proportional to the rate at which electrical energy is given to the element of charge, for the reaction velocity of the reduction of the zinc oxid by carbon is a geometrical. function of the temperature of the reacting bodiesless 10323 (1. have Zn()l-C:F ("-ZnO+C-1033 C.)

lhei.-rcti cally, with ample electrical energy at hand, immense amounts of ZnQ+C time, but. from a practical sh. dpolnt, the rate of reduction is limited by the necessity the charge,-by the maximum allowable canat +1033 G. arising from the smelting are at the same time themselves cooled to a,

more practical. knowledge of the electro charge leaving the feed pipe at a te1npera-.

k1. of zinccontents approximately 1500' (See Richards Met. C'aZn-ulotions, Part Mathematically expressed, we,

could be reduced in a very short space of for a progressive. and regular descending of positions of the upper electrodes to the bath as the main resistor, it has threespecific suband therefore the reduction proceeds from I ZnO+Fo=FeO+Zn to proceed quietly and '2 temperature best suited for condensation.

' nosoma ductance of the electrodes and by the ability to evolve the upward through the charge and not downward into the slag.

By effecting the reduction of zinc oxid in a fusion electrothermic zincproces'sthe reacting bodies are in a state of hot solution 20 to 100 timesas fast as in the zinc retort and the smelting proceeds 2 to 10 times as fast as in a copper-matting furnace.

The above. shows theelectrocheinistry of the smelting zone. The purely electrical action, of the smelting operation is partly arcing throiigh the zinc vapor and partly conductance through the solid and liquid particles of the charge. In the smelting zone, the furnace doesnot operate on the resistance principle of electric smeltingor on the arc principle, but on a combination of the two classes of electric smelting operations.

At its surface the slag has a tern eralure of +1250 C. Which is su cient tor the reactions, ZnS+Fe=FeS+Zn,

smoothly. These reactions are not so strongly endothermic the reduction of nine oxid by carbon.- They absorb both electrical heat and heat radiated and conducted upward from the slag bath.

The proper adjustments in the relative of slag can be made in several ways: (1)

Electrodes can he raised as slag level raises by any well known mechanical means, such as a differential block. In this case the slag is removed by tapping intermittently. (2) The slag can be. tapped continuously and the level of slag bath held constant.

The proper relative position and dimensions of electrodes, slag bath and charge to make the smcltingmost cfiici ent,'depend on cost of ow'er, on cost of ore, price of products, c aracter of ore and reducing agent, and on voltage at which power can best be furnished.

In order to carry out my process successfully, the electrometallurgist should. pay attention to the subordinate function of the charge. Besides furnishing the material to be smelted and acting with its productsfunctions. (a) It filters out any lead fume and condenses any lead vapor (thereby making a 99.80 per cent. pure spelter) and filters out any of the fumes of silicon, aluminum, and any dust. (Z?) it fixes any tarry vapor and. lessens the clogging u of the condenser by tar. (o) it cools t e gases to the Thereby the condenser is relieved of Work and its capacity accordingly is increased. The traiisfer of'heat units to the "descending charge by t "upward percolating gases resen the heat reqtrirements'of the smelting operation.- is gained, for the amount of electrical en ergy needed for smelting a charge of given composition is lessened and the capacity of the condenser is enhanced.

In this way a double advantage In the normal operation of the process, a

top layer 30 of carbonaceous material preferably will be used. geously be introduced through the pipes 31 which paw through the furnace root adjacent the regular charging funnels 17 and which preferably are arranged so that the carbonaceous material will gravitate around the discharge ends of the funnels and aroundthe depending electrodes. In this Wig, all vapors must first pass through this I re uc nace. By using this material in this manner, it i'smaintained at an effective temperature Without employing any heatingmeans other than the furnace, with a resultant economical operation.

This 'may advautaing medium before leaving the fur- The charging of the furnace with -the mix and also with the charcoal or equivalent material for supenreducing can be done either intermittently by directly opening the cluirge holes of by some apparatus as a louhle bell and hopper. In the latter case. a plus pressure of some reducing orindifi'ercut gas as hydrogen, carbon monoxide]; nitrogen or a miizture of the three as a high -grade rn-o luccras had bestbe applied to the charging mechanism in order to prevent the ingress of air to the furnaccduring the charging operation. simplest way is to feed the furnace continuously and directly through fire clay or cast iron pipes extending to level of the charge column. of these by the condensation of zinc in them to solid form, it is only necessary to insure that the rhaige in the feed-pipes be kept. slightly abovethc melting point of zinc 415 C. according to one of the three following ways: (1) Charging the mix hot, above 415 and below a temperature at which any amount of zinc can coexist with carbon monoxid in the gaseous state, say 500 .C.

But the best and To prevent the clogging (2) By designing the feed pipe so that the internal heat of the furnace keeps the charge above 415 and below 500 C. By jacketingthe pipe and surrounding it -With an atmosphere of gases above 415 C. and below 500 C. In any event. the frict-ional resistance to flow of gas of the mix in feed pipes ,must be so great that the -zinc vapor has the chance to condense on the descending"inix in the feed pipes, as it is well to make the furnace always strongly c'xhalant. escaping at the feed pipes can be burnt o1- -it can e fuel. This facilitates the condensation by. enriching the as for the liquid zinc'is re-volatilined Any carbon monoxid collected and used as a gaseous n the charge descends into the smelting zone and finally passes out as zinc vapor through the eductor into the con-- densing apparatus.

After themix is charged, a layer of char coal is introduced through the appropriate charging apertures. This serves several purposes. A. part of the electrical energy, 2 per cent, passes through it and present local points of arcing, givingrise to carbon vapor.- Thus the reduction of anv weak oxidizers, such as S0,, place. This prevents the these oxidizers of the zinc vapors in the condenser and reduces to a minimum the formation of blue powder. any heavy tars into lighter hydrocarbon that Wlll not. as the heavy tars will, clog up the condenser. The reduced vapors leave the furnace through the eductor 32 which is preferably inclined into the furnaee chan'iber at a relatively stee gradient, say 1""; or ll, so that while it may act as a collection chamber, it will also allow such products asmay condense therein to gravilate'hack into the furnace and there be revo-latilizwl'. This eductoris so made and connmted with the condenser, that the operator n'lay insert a rabble through the condenser and push the dust back into the swelling chamber. This eductor is heavily insulated with mineral wool or asbestos 31-3 incased in sheet iron, so that but little molten zinc will be condensed therein.

From the foregoing disclosure it will be perceived that l have succeeded in devising an electric zinc smeltinr method in which the various commercia. requirements are adequately fulfilled and that, while said method is essentially simple in character, it nevertheless is capable of yielding metallic zinc ot' a very high grade and free from the impurities which are ordinarily found in zinc bullion conunercially produced from ordinary ores.

\Vithout further elaboration, and in the light of current knowledge, the foregoing disclosure will sulliciently suggest and otherwise enable those skilled in this art to readily utilize various interchangeably available and mechanically equivalentsteps and treatments which, although perhaps cal- (ulated to appear widely different under a superficial inspection, and follow in a varied sequence. would nevertheless embody certain, if not all of the herein-described features which, from the aspect of the prior art, constitute essential and advantageous characteristics of this invention, and there fore such processes should and, accordingly are intended to be secure by Let:

(It), or H O, takes oxidization by' v coniprehehdcd in the wording and scope of the following claims.- my invention, what I" a volatile metal, which consists in electrically heating a charge proportioned to yield a fusible slag, conducting the volatile reaction products-into contact with carbon heated to its temperature of maximum reductivity, continuously replacing the carbon and condensing the metal, substantiall y as described. v i

2. A continuous smelting process of the nature. disclosed, which consists in super posing a heat reducible charge'containing a volatile metal upon a molten electrode, and causing an electric current to pass through the charge and through the evolved metallic vapors, and also through the electrode.

3. The method of smelting ores yielding a volatile metal which consists in progressively heating in the absence of extraneous air, a charge proportioned to yield, a fusible slag, conducting the volatile reaction products through the charge, thereby pro gressively cooling the same, and condensing the metal apartfrom the charge.

4. The method of smelting ores yielding a volatile metal which consists in heating, in the absence of extraneous air, a charge comprising a reducing agent and proportioned to yield a fusible slag, preventing the escape from the charge with the volatilized metal of an agent capable of combining witlr the volatilized metal, and condensing the volatilized metal apart from the charge.

5. The method of smelting ores yielding a volatile metal which consists in heating,

in the absence of extraneous air, a charge comprising a reducing agent and proportioned to yield a fusible slag, preventing the escape from the charge with the volatilizcd metal of gaseous agent capable of combining with the volatilized metal, and condensing the volatilized metal apart from the charge.

6. The method of smelting ores yielding a volatile metal which consists in heating, in the absence of extraneous air, a charge comprising a reducing agent and proportioned toyield a fusible slag, preventim the escape from the charge with the volatilized metal of a gaseous agent capable of oxidizing the volatilized metal, and condcns ing the volatilized metal apart from the charge.

7. The method of smelting zinc-ores which consists in heating, in the absence of extraneous air, a charge of ore and agents having agreater affinity for other elements of the volatilized products than for zinevapor, yield a fusible slag, preventing the escape from the charge with the zinc-vapor of a gaseous agent capable ofcombining with the zinc-va por, and condensing the zinc vapor apart from the charge.

8, The method of srnelting zinc-ores the charge being proportioned to which consists in progressively heating, in the absence of extraneous air, a charge consisting of'ore and agents having .a greater -theescape from the charge of a gaseous affinity for other elements, of the volatile products than for -zinc, the charge being proportioned to ducting the volatile reaction products through the charge, thereby progressively cooling the same, and maintaining the temperature of the charge such as to prevent agent capable of oxidizing the zinc-vapor, and condensingthe zinc apart from the charge.

9. The method of smelting ores yielding a volatile metal which consists in heating a diarge of ore, carbon, and agents having a greater aflinity for other elements of the volatilizedproducts than for Zinc-vapor, the charge being proportioned to yield a fusible slag, conducting the volatilized zinc through the charge, preventing the escape from the charge with the'zincvapor of a gaseous agent capable ofcombiiiing with the zincvapor, condensing the zinc-vapor apart from thecharge, and separately collecting such of the products as would combine with the zinc-vapor.

10. The method of smelting ores yielding a volatile metal which consists in progressively heating, in the absenceof extraneous air, a charge comprising a reducing agent and proportioned to yield a fusible slag, conducting the volatile reaction products through the charge, thereby progressively cooling the same, preventing the escape fromthe chargeof an agent capable of combining with the volatilized metal, and. con densing the metal apart from the charge.

11. The method of smelting zinc-ores which consists in progressively heating a charge of oreand agentshaving a greater affinity for other 'elements of the volatilized roducts than for zinc-vapor, the charge eing proportioned to yield a fusible slag,-

conducting the volatile reaction products through the charge, thereby progressively cooling the same, preventing the escape from the charge with-the zinc-vapor of a gaseous agent capable of oxidizing the zinc-vapor, and condensing the'zinc-vapor apart from the charge.

12. The; method of smelting ores yielding a volatile metal which consists in progressively heating a charge of ore, carbon, and

agents having a greater afiinity for other elements of the volatilized products than for zinc-vapor, the charge being proportioned to'yield a fusible slag, conducting the volatilized zinc. through ithe charge,

thereby progressively coolingthe same, pre-,

venting the escape from the charge with the zinc-vapor of a gasous agent capable yield a fusible slag, con

of combining with the zinc-vapor, condens-.

ing the zinc-vapor apart from the charge, 85 and separately collecting such of the products as would combine with the zinc-vapor.

13. The method of smelting ores yielding avolatile metal which consists in progressively heating a charge comprising carbon, and proportioned to yield a fusible slag, conducting the volatileireaction products through the charge in the direction to progressively cool the same, providing temperature conditions of the charge such that any other volatile product escaping from the charge with the volatilized met-a1 will be rendered incapable of oxidizing the vola-' tile metal after escaping from the charge, and condensing the volatilized metal apart from the charge;

14. The method of smelting ores yielding a volatile metal which consists in heating a charge comprising carbon and proportioned to yield a fusible slag, conducting the volatilized reaction products through the and condensing the metal apart from the charge. I v

16. The method of smelting zinc ores, which consists in electrically progressively heating, in the absence of extraneous air, a charge proportioned to yield a fusible slag, conducting the volatile reaction products throughthe charge and into contact with carbon-heated to a reducing temperature, and condensing the zinc.

17. The method of smelting zinc ores, which consists in progressively/ heating, 1n

the absence of extraneous air, a charge proportioned to yield a fusible slag, said charge comprising carbon, conducting the volatile reaction products through the charge and into contact with portions thereof heated to the temperature of maximum reductivlty of carbon, and condensing the'zinc apart from the charge.

In testimony whereof I affixmy signature, 12!" in the presence of two witnesses.

WOOLSEY MoAQ JOHNSON. Witnesses: i

J. THoMsoN,

L. A. WA'rson.

Correction in Letters Patent No. 3,080.912.

1913, upon the application of Woolseyv McA. Johnson, of Hartford, Connecticut, for an improvement in Methods of Electrically bmelting Volatile Metals, an

error appears in the printed specification requiring correction as follows: Page 5, Y line 97, for the word as read e; and that the said Letters Patent should be read with this correction therein that the same may conform to the record of 1' the case in the Patent Office.

Signed and sealed this 30th day of December, A. D., 1915.

' [SEAL] T. NEWTON,

Acting Commissioner of Patents.

It is hereby certified that in Letters latent No. 1,080,912, granted December 9; i

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