US1069085A - Process of recovering zinc and other volatile metals. - Google Patents

Description

T. HUNTING"I'ON & F HEB ERLEIN. rnoonss 0F REGOVER I NGZING AND OTHER VOLATILE METALS.

APPLIOA TION FILED 001.25, i910.-

1&069085, Patented July 29, 1913.

' WITNESSES:

a i Y r r ATTERNEYS. k

UNITED STATES PATENT OFFICE.

u'nonxs mm'imo'ron, or ennon, ENGLAND, Ann mammal: rmnnnmam,

-- rmnxron'r-on-rnn-uam, ennmanr.

rnocnss or moon-mine znwann ornnn-vom'rrm METALS.

Savignystrasse, Frankfort on the Main, Germany, have lnvented certain new and useful Improvements in Processes of Recoverin Zinc and other Volatile Metals, of

which the following is a full and exact specification. Owing to the deficiencies of the processes in general use up to now for the distillation of zinc ores in muffle furnaces, efforts,

have been made with a view of carrying out the zinc distillation in shaft blast furnaces, but-all such trials have been-unsuccessful. The failures are mainly due to the working of the blast furnace itself. Owing to the complete liquefaction of the slag and to the continuity of the process, it is found impossible to keep the escaping gases sufiiciently free from oxygen contained in the air blast and alsofrom other oxidizing gases, (carbon dioxid, CO and the like), the

presence of such oxidizing gases making it impossible to obtain the zinc vapors free from oxid and to then condense them into a compact metal. It is for these reasons that thus far only zinc oxid or zinc dust containing a high percentage of zinc oxid have been obtainedin blast furnaces.

The presentinvention has for zinc in a compact metallic form by means of a process in which air is blown through muffle residues.

the mass of ore. I

The invention is based on a well known process, the object of which is to volatilize the zinc and to recover it in the form of zinc oxid. This known process. consists in mixing zinc ores or 'zinkiferous products in a pulverulent or granular-form with fine coal or other fuel when not already contained therein, n-sfor instance in the case of The mixture is then fed into a suitable furnace, such as for instance the Huntingtcn-Heberlein converter furnace, and after starting ignition, submitting it to the action of a current air traversing the layer of material under treatment from below up to the surface of the charge. Owing to the phenomena of combustion,

Specification of Letters Patent. Application filed October 25, 1910. Serial 110. 589,082.

- v vent-ion this known an its object' blowing process is modified n sucha way the solving of the problem of recovering reduction and oxidation which take place, the zinc is volatilized and carried along in the form of oxid together with the escapmg combustion gases and is then recovered by' means of suitable filterin devices or the like. After the 'more or ess perfect removal of the zinc from the charge, a sintering of the furnace contents takes place and the process is thus finished. The sintered residues are then discharged, for instance by tilting the converter and the furnace is then fed with a fresh charge. Contrary to the blast furnace work, the process therefore is a discontinuous one.

In the process just described, as well as in other similar volatilization recesses where the air current is directed low to the top, the intention and result was always to recover the zinc in form of oxid. The methodwas either to employ a relatively thin layer of material in connection with a relatively low air pressure or a relatively thick layer with a relatively high air pressure. In both cases the gases always contained oxygen and other oxidizing gases (carbon dioxid and the like) in excess and the nascent zinc va rs therefore were con verted into oxid. n all these known processes it is neither intended nor is it ossible to recover the zinc in aliquid metallic form,

rem bepatented July 29,191abecause thepresence of anexcess of oxygen,

and otheroxidizing gases is thereby in-' ,evitable. No'w accordln to the present in that the air and gas current is not directed from below to the top but reversed, namely from the'surface of the charge through it to the bottom, the layer of charge being comparatively thick. In the course of trials carried out with .these new methods, the startling result was observed, that oxidation of the zinc vapors can be avoided, so that thesevaP rs 'on leaving the charge may be almost completely condensed and liquefied by suitable means and thus be recovered in a compact metallic state.

In the accompanying drawing illustrating a furnace adapted for performing the process in accordance with our invention a is a converter furnace filled with the charge a resting on the perforated grate f, while cl is 'a cover tightly secured upon the converter and provided with an air inlet 6. The out-v let for the gases and vapors is'at g. The

discontinuous air Converter can be-ti'lted over by turning the trunnions e on which it is supported.

The process may be carried out for instance as follows: The zinkifero'us ore or zinc products mixed with fuel is fed in a comparatively thick layer into a converter furnace. ()n the surface of the charge an ignition fire'is started and through theair-tight converter-hood a current of air is admitted. First a combustion of the fuel will take place in the upper part of'the layer, and

owing to the increase of temperature therebycaused, and also owing to the reaction of the ore-particles with the carbon present in the mixture and the carbon mo-noxid developed by the combustion, the zinc will hereduced in this upper layer and will pass vertically downward in form of metallic vapor together with the gas. current. The gases "coming fromthe upper layers will grad. ually preheat the mixture of ore' and. coalbelow., After some time, the whole'fuel of the upper layer will be'burned. out bringing the temperature in this layer to such a degree, that the mass is sintered. In the meantime, the zinc fromthis upper layer has dis-' tilled out, the completeness of its removal being considerably furthered by the close contact existing'in the moment of sintering between the coal still present in the charge, and the ore particles. Through the sintered upper layer which is screen-like interspersed with air-ch'annels,-the fresh air current is passing and reaches the lower unsintered layer, which still contains the bulk of its fuel-contents. The same phenomenon as in the uppermost layerwill now take place here, i. e. the fuel will be burnedby the oxy-' gen of the airand theKzi-nc volatilized, until finally the sintering of the whole mass is accomplished. These phenomena will continue downward from one layer to the other, until the sinte-ring zone has reached the bottom part of the charge, when the process is finished. The gases and metahvapors escaping .from the layer'which is near the sintering state, pass through the layers lying beneath until they escape at the bottom of the charge. Thus the gases Will preheat these layers of charge and prepare them, by. reducing and decomposing the oxids; carbonates, sulfates and like compounds contained in the charge and injurious to thesubsequent production of metallic zinc vapors. On the other hand,

oxidizing constituents of the gases will be reduced in passing through the still unsintered layers of the charge intermingled with live coal, so that on leaving the charge at the bottom, the gases essentially consist of only carbon monoxid (CO) and nitrogen.

The zinc vapors mixed with thegases will first be partly oxidized and retained in the charge in the form of zinc oxid, and partly condensedito a metallic state in the inferior cooler layers of the charge. During a cercar'ry along the carbon monoxid and the oxitain preliminary stage of the operation,

which according to the prevailing conditions I will be shorter or longer, no zinc vapors will thus escape from the lower part of the charge, but only the gases developed by the combustion of the carbon and the decomposi tion of the carbonates, sulfates, etc; as soon however as a sufiiciently high temperature is reached also in the lower layers of the charge, the principal stage of the process begins, during which also the zinc vapors will escape and may be condensed after having left the charge, by suitable. means, for in;

stance by .causing the gases to pass over cooled surfaces. Owing to the working of the charge in the preliminary stage and also to the reduction of the carbonic dioxid (CO contained in the gases, by'the incan descent coal of the charge, the gases are absolutely clean,'and. consist essentially of only \monoxid. of carbon and nitrogen, the condensation of the zinc vapors to liquid. (or solid) metallic" zinc is obtained without diifi culty and the formationof zinc dust and zinc oxid avoided. The astonishing phenomenon is, that in the process described the zinc does not escape from the charge in the form of zinc oxid, but mainly in. the form of metallic zinc vapors, capable of being condensed to liquid metallic zinc, whereas in the hitherto known analogous processes and in the known blast furnace work, only zinc. oxid could be obtained,'o'r under most favorable, circumstances an inferior quality of zinc dust. This is most probably due to the.

following reasons: .When in the process,

where an air current passes through the charge sintering the same, and the current is directed from the bottom to the top, it is not possible to obtain,.a uniform distribution of the-air over the whole area of the charge.

In consequence of their tendency to expand, the gases are seeking a passage throughthc charge at those'points, which otter the least resistance. Thu's crater-like channelswill be formed in some parts of the charge and through these'channels the air reaches the surface of the charge in a more or less unaltered condition, mixing there with the gases and. vapors escapin from the charge. In addition, this crater-formation causes an irregular combustion and sintering to' take place, so that, the-sintering-does not propagate upwardly by uniform layers, but irregularly with respect to the horizontal and vertical section of the mass. Furthermore,

I the above-mentioned preparatory preheating and reduction is prevented and there are many parts of the mass in which the volatilization of the zinc is taking place simultaneously with the reduction of the abovementioned injurious oxids, sulfates, carbonthat the gases holding the zinc vapors also ates, and like compounds, with the result d-izin elements (carbon dioxid, etc.) generated y the reduction of the oxids, sulfates, carbonates, etc., whereby the zinc vapors are converted to oxid. The word oxidizing is used herein the sense that the elements gen erated by the reduction of oxids, sulfates,

carbonates, and like compounds exert an oxid'izing action upon thezrnc vapors. If however according to the present invention, the

s and air current is directed from the surace of the charge downward, and a relatively high layer of charge used, the expansion of the gas current is counteracted by the fact of the resistance offered by. the

charge tothe assage of the gases which increasestowar the bottom-in consequence of the greater density .of the lower layers of the charge Andthis will have for effect that the gas current is distributed uniformly over 20 the whole area of the charge and crater-like formations are avoided, hence a uniform preparation of the charge and a uniform propagation'of the sintering toward the bottom will take place. And hereby again it is possible to have the escaping gases contain only carbon monoxid and vapors of metallic zmc.

From the foregoing it is, obvious that the success of the invention depends upon using relatively thick layers of charge, a rela'- tively thick layer meaning aheight of for instance 100 centimeters. If the layer is too thin, there will be no preparatory reduction and decomposition of the oxids, sulfates, carbonates, etc., nor will the gases be cleaned" from oxidizing constituents, which according to the above explanations, is indispensable for obtaining condensable metallic zinc vapors. The height of layer required for each case however depends upon the percentage of zinc and the nature of the material to betreated, and must be established for each material by practical experience.

It is evident that the pressure and quantity of the air passing through the mass must be proportionate, that isto say adapted to the height of layer employed and other prevailing circumstances. Pure oxygen ora'ir enriched in oxygen or preheated air or oxygen may of course be employed instead of air/ In: workiiigathelpiocess practically, it was found that it was difiicult to distil the zinc out of the lower layers of the charge in a metallic form, which difliculty may be ex-' plained by the fact that the bottom layer of the charge does not exert asuflicient reducing action upon the'combustion gases and zinc vapors prior to their escape from the charge. To avoid this difficulty it is advis-- able -to add in the bottom layer of the charge a larger quantity of reducing fuel than in the rest of the charge. Owing to this in crease of reducing fuel in the lower layer, the dangerof reoxidation of the zinc vapors is lessened and it is possible to distil the zinc in metallic form also out of the lower layers of the charge. Itmight be advisable to'have no ore at all in the bottom layer ofthe furnace, but to allow the charge to rest upon a layer of reducing fuel (preferably coke). This reducing bottom layer might serve as a grate, by putting for instance on the bottom of the furnace first a la-yer of coarse coke, and upon this alayer of finer coke, upon which-the charge itself 'is fed. It might also be advisable to separate the charge into several layers and provide a layer of charge richer in fuel (or of fuel only) between two such layers. The arrangement of layers of higher reducing capacity between or un..lcrneath the charge may have another favorable effect, inasmuch as these layers. secure, during the whole operation, a more perfect reduction of the oxidizing constituents of the'gases and of the already generated metallic oxid.

From the process of distilling zinc in blast fu1-naces,;w-l1icl1 never has been successful, the present'gprocess differs substantially in that ('1) iii'Lt-he present processthe slag is not converted into a fluid state, but' only sinterecl; (2) the present process is not carried. out continuously, but discontinuously, 27. c. in each operation a determined quantity of charge is submitted to distillation and when completed the work begins once again. As in the well-known blast-furnace distil lation the zone at which the slag is liquefied must nearly coincide with the zone at which the generation and distillation of the zinc takes place, it is inevitable thatpart of the air blown in or the carbon dioxid generated by the combustion, reaches the zinc distillation zone and thereby reoxidizes the zinc vapors. Moreover, in the blast furnace worlgthere is not suflicient preparation of the charge, '5. c. injurious oxids, carbonates, sulfates, etc., are not sufficiently reduced and decomposed before zinc reduction is taking place and because in blast furnace the layers are naturally charged loosely, the gases traverse them quickly and without the necessary close contact with the particles of the charge.

The startling result obtained by the present invention, in recovering in a metallic state the zinc vapors on their leaving the charge, may partly be ascribed to the factthat the charge forms a densely stratified mass, the mass of material being a pulverulent or granular state. or when in form of briquets, 'the spaces between the briquets must be completely filled in with fine coal or fine charge material. The thus obtained densitv of the charge will further the uniformity of the gas distribution, and a more intimate contact of thegases with the particles of the charge, and also will slacken the passage of the gas current through the mass of the charge, whereby a uniform and tained.

'WVOIlU-Bd with profit on materials poor in efficacious The trials on which the present invention 1s based, were carried out in a converter furnace, such as is ma'deu se of in the Huntlngton-Heberleln' process, for roastinglead ores. The converter, and consequently the charge contained therein, was tapered toward the bottom and it appears that this tapering form of, thecharge is of a certain importance for the success of the invention, especial-1y for the purpose of producing clean metallic zinc vapors. sequence of this downward tapered section of discharge, the uniformity of the gas distribution is furthered, and-the craterformation counteracted, a better preparation ofthe charge is secured and a better cleaning of the gases, inasmuch as the downward passing gases are coming into more intimate contact with the charge in the lower reduced section of the furnace. Furthermore it-has been found -in thepractical working of the invention, that a certain amount of water or other vaporizable liquid in the charge exerts a favorable influence upon the course of the process. It would seem that owing to such water contents the preliminarylperiod, during which the charge is being gradually brought to the rolatilization temperature of the zinc, and prepared in other respects, is extended, and that in the mass of the charge a system of fine channels is formed by the, escaping water vapors. The volatilization temperature is thereby distributed with greater uniformity over the whole mass of the charge. Moreover, the favorable effect of the water is perhaps due to certain chemical reactions of the water (formation of hydrogen, decomposition of.

injurious compounds, etc). In. comparison with the present zinc distillation processes in muffie furnaces, the present process'has the advantage of much greater cheapness and .very simplified working. Moreover the new process can be zinc, such as for instance in the case of retort residues and ore-talllngs, low grade zinc ores and the like. A further advantageof the present invention consists in the facti that the zinc recovery-is a good one Doubtnot necessarily confined to the production of'me'tallic zinc. In making 'use of the methods characterizing the process, zinc may also be recovered in form of oxid, if the zinc-vapors after hav ng escaped from the charge, are allowed to come in contact with air and thereby burned tooXid.

The invention is not only applicable to zinc, but also to other volatilizable meta-ls,

preparation of the charge is ob- Because in consively throughout the lower portions of the charge, the metal having the lowest tem per-ature of volatilization first passes from the furnace as a vapor, and then the metal having the next higher temperature of volatilization passes from the furnace, and so on. If, for instance, zinc and lead are mixed together in the charge, substantially all the zinc vapor escapes first, and then, after the bulk of zinc is volatilized, the lead .vapor starts to pass from the furnace, so

that the two may be recovered separately, as, for example, by directing the zinc vapors into one place and then diverting'the following vapors into another place at the time that the lead starts to volatilize; or, as an. alternative. to the procedure in this example, the. air current may be shut off and the-process terminated after the volatilization of the zinc is completed. The residue from which the zinc content has been extracted then remaining in the furnace, may be treated in a blast furnace for recovering the lead content. Easily volatilized metals, such as arsenic, antimony, mercury, already escape priorto the volatilization, of the zinc and may also be recovered separatelyif desired; la ing thus described our invention whatwe claim as new and desire to secure by, Letters Patent, is:

LflQhe process of recovering zinc and other volatile metals fromores or other mareducing, decomposing and reducing by said downward escaping combustion gases the compounds of the charge which may be injurie-us toth'e subsequent production of metallie vapors, reducing the oxidizing constituents of the gas current by the incandescent fuel, distillingthe volatile metals out of the charge, condensing the metallic vapors, sintering substantially the entire residues and discharging the sintered mass.

for preparing the furnace to receive-a fresh charge.

2. The process for recovering zinc and other volatile metals from ores or other materials, which consists in charging a comcompounds of the charge which may be injurious to the subsequent production of me tallic vapors, reducing the oxidizing constituents of the gate current by the incandescent fuel, distilling the volatile metals cutof the charge, condensing the'metallic vapors, sintering the residues and dischargi fresh charge. 1

ing them for preparing the furnace to receive a fresh charge.

3. The process of recovering zinc and other volatile metals from ores or other materials, which consists in charging a comparatively thick layer of the ore-or other material mixed with reducing fuel and moistened with a vaporizable liquid, into a suitable furnace, igniting the charge at the top,

forcing an air current downward throu h the charge, decomposing and reducing hy the downward escaping combustion gases the compounds of the charge which may be injurious to the subsequent production of metallic vapors, reducing the oxidizing con- I stituents of the gas current by the incandescent fuel, distilling the volatile metals out of the charge, condensing the metallic va- )ors sinterin the residues and dischargin them for preparing the furnace to receive a i. The process of recovering zinc and other volat le metals from ores or other materials, which consists in charging a comparativelj thick layer of the ore or other material mixed with reducing fuel into a suitable furnace and upon layers of in creased reducing power, igniting the charge at the top, forming an air c urrent'downward through the charge, decomposing and reducing by thc downward escaping combustion gases the compounds of the charge which may be injurious to the subsequent production of metallic'vapors, reducing the oxidizing constituents of the gas current by the incandescent fuel, distilling the volatile metals out of the charge, condensing the metallic vapors, sintering the residues and discharging them for preparing the furnace to receive a fresh charge.

5. The process of recovering zinc and other volatile metals from ores or other ma-. terials, which consists in charging a comparatively thick layer of the ore or other material mixed with reducing fuel into a suitable furnace and upon layers of fuel, igniting the charge at the-top, forcing an air current downward through the charge, decomposing and reducing by the downward escaping combustion gases the compounds of the charge which may be injurious to the subsequent production of metallic vapors, reducing the oxidizing constituents of the gas current by the incandescent fuel, distilling the volatile metals out of the charge, condensing the metallic vapors, .sintering the residues and discharging them for preparing the furnace to receive a fresh charge.

6. The process of recovering zinc and other volatile metals from ores or other materials, which consists in charging a com paratively thick layer of the ore or other material mixed wit-h fuel and moistened with'water, into a converter furnace tapered toward the bottom, and upon layers of increased reducing power, igniting the charge at the top, forcing an air current downward through the charge, decomposing and reducing' by the downward escaping gases of 1 sintering the residues and discharging them,

for preparing the furnace to receive a fresh charge. r

w 'Lfljlie process of treating ores or other materials containing zinc and other volatile metals, which consists in charging a comparatively thick layer of the ore or other material mixed with fuel into a suitable fur,- nace, igniting the charge at the top, forcing an air current downward through the charge, decomposing and reducing by',.the downward escaping combustion gases the compounds of the charge which may be injurious to the subsequent production of metallic vapors, reducing the oxidizing constituents of the gas current by the 1ncandescent fuel, distilling the volatile metals out of the charge, burning the metallic vapors to .oxid after-they have left the charge,

downward escaping combustion gases the compounds of the charge which may be injurious to the subsequent production of metallic vapors, reducing the oxidizing constituents of'the as current by the incandescent fuel, distilling one or more of the volatile metals out of the charge and leaving behind in the residues the other less volatile metals, condensing the metallic vapors, sintering substantially the entire residues and discharging thesintered mass for preparing the furnace to receive a 'fresh charge.

9. Theprocess of recovering zinc and other Volatile metals from ores or'otherma- 5 terials, which consists in charging a comparatively thick layer of the vore or other material mixed with fuel into a suitable furnace, ignitingthecharge at the top, forcing an air current downward through the 10 charge, decomposing, and reducing by the "downward escapiitg combustion gases and the compounds of the charge which may be injurious to the subsequent production of metallic vapors, reducing the oxidizing con 15 stituents of the. gas current by the incandescent fuel, distilling the volatile metals one after the other; out of the charge, con densing separately the different metallic vapors, sinte'ring the residues and discharging them for preparing the furnace to receive a 20 fresh charge.

In testimony whereof we havensigned our names to this specification in the presence of two subscribing witnesses.

THO As HUNTINGTON; I I FERDINAND HEBERLEIN.

'l/Vitnesses:

JEAN GRUND, CARL GRUND.

Glipies of this patent may be obtained for fivejc'ents each, by addressing the Commissioner of Patents 1 Washingtom). c.

It hereby certified that int Letters Patent No. 1,069,085, granted July 29, 1913, upon the application of Thomas Huntington, of London, I England, and Ferdinand Heberlein, ot Frankfort-on-the-li/liain, Germany, for an improvement in "fPro cesses of Recovering Zinc and other Volatile Metals, an error appears in v the printed specitic-ation requiring correction as follows: Page 5, line 43, for the word. forming? readforcing; and that the said Letters Patent" should be read with this correction I therein that the same may conform to the record of the case the Patent Qtfice.

Signed and sealed this 7th day of October, A. D., 191 3. d

R. T. FRAZIER,

Acting Commissioner of lqtents.

discharging thesintered mass for preparing the furnace to receive a 'fresh charge.

9. Theprocess of recovering zinc and other Volatile metals from ores or'otherma- 5 terials, which consists in charging a comparatively thick layer of the vore or other material mixed with fuel into a suitable furnace, ignitingthecharge at the top, forcing an air current downward through the 10 charge, decomposing, and reducing by the "downward escapiitg combustion gases and the compounds of the charge which may be injurious to the subsequent production of metallic vapors, reducing the oxidizing con 15 stituents of the. gas current by the incandescent fuel, distilling the volatile metals one after the other; out of the charge, con densing separately the different metallic vapors, sinte'ring the residues and discharging them for preparing the furnace to receive a 20 fresh charge.

In testimony whereof we havensigned our names to this specification in the presence of two subscribing witnesses.

THO As HUNTINGTON; I I FERDINAND HEBERLEIN.

'l/Vitnesses:

JEAN GRUND, CARL GRUND.

Glipies of this patent may be obtained for fivejc'ents each, by addressing the Commissioner of Patents 1 Washingtom). c.

It hereby certified that int Letters Patent No. 1,069,085, granted July 29, 1913, upon the application of Thomas Huntington, of London, I England, and Ferdinand Heberlein, ot Frankfort-on-the-li/liain, Germany, for an improvement in "fPro cesses of Recovering Zinc and other Volatile Metals, an error appears in v the printed specitic-ation requiring correction as follows: Page 5, line 43, for the word. forming? readforcing; and that the said Letters Patent" should be read with this correction I therein that the same may conform to the record of the case the Patent Qtfice.

Signed and sealed this 7th day of October, A. D., 191 3. d

R. T. FRAZIER,

Acting Commissioner of lqtents.

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