US2457544A - Method of condensing zinc vapor - Google Patents

Description

E. c. HANDWERK ET Al. 2,457,544

METHOD OF CONDENSING ZINC VAPOR 2 Sheets-Sheet 1 Dec. 28, 1948.

original Filed Nov. 3, 1945 /vfifmr C. HAz/P INVENTORS @m FMMJM @www ATTORNEYS Dec. 28, 1948. E. c. HANDWERK ET AL 2,457,544

METHOD OF CONDENSING ZINC VAPOR Original F'iled Nov. 3, 1945 2 Sheets-Sheet 2 R//z//A/ C, //A Nom/ERK 641A Ry (HAUPT- INVENToRs AT TO RNEYS Patented Dec. 28, 1948 U NITED STATES PAT;

' M l 24575i4-. l. METHOD OFCONDENSING ZINC VAPOR n Erwin C. Handwerk, George'l'ltiahlerlr and Harry C. Haupt, Palmerton, Pa., assignorsto The New Jersey Zinc Company, NewYork; N. Y.',"a corporation of New Jersey Y Original application November 194,5,HSerial No.

626,508. Divided and this application Septemv ber 11, 1946, Serial No. .636,172 p p 2 Claims. (Cl.-75-88)f b This invention relates to' condensing zinc vapor, and has for its object an improved method of condensing zinc vapor.

In the customary pyrometallurgical practices of smelting zinc ores, the zinc is recovered as molten metal by condensing the zinc vapor con' tained in the gaseous products of the smelting operation. The condensers ordinarily used for condensing the zinc Vapor produce a considerable amount of zinc dust or `blue powder which usually isreturned to the smelting operation. For eX- ample, the condensers heretofore used with modern externally-heated vertical zinc retorts commonly produce blue powder or zinc dust amounting to '7 to 15% of the output of (zinc. It is ordinarily necessary to recirculate this blue powder through the vertical retorts,` since itis usually not in the form of salable zinc dust and is difiicult to melt down to liquid zinc withthe use of the heretofore available equipment. A particular object of the invention is the pro` vision of an improved method of condensing zinc vapor diluted with ordinary smelting gases, such as carbon monoxide and the like, with the formation of only a minimum amount of blue powder. The invention is particularly adapted for use with smelting equipment of relatively large capacity such as modern externally-heated vertical zinc retorts or electro-thermally heated retorts.

In accordance with the method of the invention, a gaseous stream containing the zinc vapor to .be condensed is passed through a shower or rain of molten zinc particles in a suitable `condensing chamber having a body of molten zinc in the bottom thereof from whence a substantially continuous and upwardly-directed sheet or shower of molten Zinc is hurled by centrifugal'v action with such violence as to provide by itself and by its splashing against the confining upper portion of the chamber turbulent sheet-like showers of molten zinc through which the gas stream passes. A condenser especially adapted for the practice oi the invention is described andV claimed in our copending application Serial No. 626,508, nled November s, 1945, of which this application is a division.

The foregoing and other novel features of the invention will be best understood from the following description taken in conjunction with the accompanying drawings, in which 4 Fig. 1 is a longitudinal sectional elevation of the aforementioned condenser,

Fig. 2 is a transverse sectional elevation onV the Section une 2 2 of Fig. y1, and

...JL o

Fig. 3 is atop plan view of the condenser.u f

Y The'condenser illustrated-in the drawings comprises a generally rectangular condensingl chamber -5 having a zinc vapor inlet S approximate one end andan exhaust or waste gasy outlet-f7 approximate` its other end. The condensing chamber is lined withsuitable refractory vmaterial and is exteriorly equipped with air or watercooling jackets 8 having appropriate inlets and outlets for the cooling medium as conventionallyV indicated by the arrows on the drawings: -The zinc vapor inlet B is connected by a pipe 9 to the source of zinc vapor, such as a Vertical zinc smelt-Y ing retort. 'The zinc vapor inlet 6 and the-gas outlet 'I are shielded by depending refractory bailles I0 and II, respectively, to prevent splashing or spraying of molten Zinc into the inlet Aand outlet. The condensing chamber communicates, beneath the` lower edge of its end wall I2, with a discharge well I3 having an overflow spout I4 determining the level (a) of the body of molten zinc in the condensing chamber. A collecting trough I5 receives the moltenmetal overflowing"y the spout VIII andA conveys it to casting equipment or the like. The lower portion of the end `wall I'2 dips into the molten metal between ithe 'con-V densing chamber-and the discharge 'well and seals the condensing chamber from theV atmosa phere at this point. The volume of molten zinc inr the cpndensingnchamber is thus maintained substantially* constant by" continuously "withdrawingmolten zinc from the chamber as zinc vapor is condensed therein. l Y A Y A generally cylindrical rotor i6 is mounted within the condensing chamberl. The rrotor is carried by a hollow or axially-bored metal'shaft, I I mounted in vbearings l8`outside the condenser.v

The shaft I I is `horizontally disposed and extends through the side walls of the condensing cham# ber between the zinc vapor inlet and ther gas o ut" let in a direction generally transverse `to krthe direction of gas flow through the chamber. The rotor may be constructed of graphite,"` silicon carbide or other suitable refractory, and is sepa? rated from direct contact withthe shaft II`by' a sleeve I9 of insulating cement. The shaft I'I has a plurality of circumferentially spaced peripheral ribs 20 embedded in the cement sleeve, and

the bore ,of thefrotor `has a plurality of spaced l. recesses 2| lled with the cement of the sleeve, yso

that the'rsh aft, sleeve rand rotor are effectively keyedv togther. The shaft Il is cooled by .the flow of a cooling medium, such as water, tljir'oughY its L axial bore, the cooling medium y being suppll dy mbe @met@nagaatthe;starter;afgeeft-2.5

and discharged from the other end through a pipe 23.

The peripheral surface of the rotor I6 has a plurality of circumferentially spaced pockets or cups 2d; "The shaft IFI :is positioned at .a .level substantially above that of rthe `rnolten zinc adapted to be held in the chamber 5, and the rotor I6 is of such outside diameter that its low# er-most pocket is beneath the molten :zinc level.

(a) The rotor is rotated by means of a pulley secured to the shaft i1 Aand operatively *con* n emerges from the body of molten Zinc the pickednected to a suitable source of power,`"sa nch 'as an'f' electric motor (not shown).

The condenser is provided with effective seals for preventing the leakage ofzinc vapor through up lmolten .zinc is lthrown by centrifugal action from the pocket upwardly into the gaseous stream passing ithrough the condenser. The

ponkets 'pass-'dn rapid succession through the body of ,molten zinc with the result that a sub.

` st'ant'iallyv continuous upwardly-directed shower and the freezing of molten Zinc intheaperturesin the side walls through which the shaft Il eX'f" tends. Thus, the rotor I6 has a laterally-.extending sleeve 26 at ea-ch end thereof surrounding the cement sleeve `I 9 where the .latter extends through the wall of thecondenser. rIfherotating sleeves 26 extend through stationary sleevesll. Each stationary sleeve 2l .has a `constricted portion `28, near its outer end, to .provide a close clearance withthe rotating sleeve 26,.and -is elsewhere spaced from the rotating sleeve to provide an elongated inner annular space .29. The outer ends of the yconcentric sleeves I9, 26 and 2l are enclosed in a gas'seal vcomprisinga tight fitting cap or housing 3l having a gland bushing .32

through which the vshaft Il extends. A suitable non-oxidizing gas, such for example as a portion ofthe exhaust gas exiting .from the condenser through the outlet l, is .pumped into the caps SI through the inlet pipes 33 to maintaina sufciently .high gas .pressure Within the caps to prevent;

zinc vapor and diluting gas from ilowing outwardly between the stationary sleeves 2l and .the rotating sleeves 26.

The sleeves 26 and 2l are so.shaped that molten metal does not accumulate yin .the elongated an-y nular space 29 between the sleeves, but on the contrary runs out by .gravity into the molten zincV at the bottom of thecondensing chamber. Thus, the ends of the stationary sleeves 2T extend'into annular grooves 34 in the ends v,of the rotor I6, and the lower portions of these ends .are

internally beveled `or thinned to form :spouts 35, for discharging by gravity any molten .metal en? tering the space 29 between the sleeves. lThe annular grooves 3E are outwardly flared -to .facili-Y tate the now of molten metal therefrom. Tho upper portion of the end .of each sleeve .2711s beveled or thickened to form a backwardly sloping surface 36 for guiding any molten .metal falling on -or wetting the .upper surface of the sleevesy towards the condenser wall and. thence dow-nwardly over the sleeve to the body of molten metal. Y v

y In vthe practice of the invention in .thezcondenscr illustrated in the drawing, a lcontinuous .stream of gas -containing zinc vapor enters the condensn ing chamber beneath the baille I0 of the inlet, 6, and flows in a generally horizontal direction through the chamber to the exhaust gas outlet .'l. Where the entering Vgas is derived from a vertical retort smelting operation it will have a .temperature of around 820 to 900 C.. .and will generally contain around to 50% zinc vapor diluted for the `most part with carbon monoxide gas. .Dissiby regulating the cooling medium flowing through the :jackets 8 to maintain within 'the Acondenser an operating temperature of about :5.00 to 550 C. The rotor I 6 is rotated 'ata V'relatively high speed,

p aticn of heat from the condenser is `controlled .of moltenfmetalisfthrown into the gaseous stream. 'IIThe-poclnets 12d-'have a generally scoop-like secn'tiornvviizh ya relatively long advancing fiat surface and, a shallow semi-circular depression at the inner end or bottom of the pocket. The pockets terminate .short of the .circumferential peripheral4v ends of the rotor, .so that little nr .no molten metal 'is 'thrown' laterally against `the .side walls of the condensing chamber'. The npw-'ardlydirected and .rapidly succeeding sheets orsliowers of molten metal splash into the .shower Aorwrain Cooling oifthe shaft Il permits the use of a metal shaft, and the sleeve [9 of insulating ...cement inhibits appreciable cooling of 'the condens-` ing 'chamber `by "the cooling 'medium owing through' the shaft, .and .eliminates any 'thermal stressesv in the rotor" I6. The special .conliguration of the stationary sleeve 'Z1 prevents the colilection and freezing .of 'Zinc metal in the .close clearance between the sleeves 26 and '2.1, `and consequent stoppage of the drive shaft.- VThe ,gas seals prevent 'the escape ofzinc vapor through the rotating contact between the sleeves .2,6 'and 2l, and 'thus insure free relative .movement `of .these'sleevesL I While theinvention is ,particularly applicableV tothe condensation of' zinc -vapor'from ther gaseous products .of Zinc smelting operations ycarried out in externally or electrically heated retorts;

where the zinc V'vapor lcontentis Vrelatively ,nig-h,

it is also applicable'to the condensation of ,zinc vapor fromY larger relative .amounts fof #diluting gases. .For example, the invention may be ladvantageously applied to l(zonden.sing Zinc vapor from the gasesproduced in Zincsmelting opera-v tions" vcarried out in blast -or cupola furnaces,- where ythezinc vapor content of 4the gas maybe as .low .as .2 to .5%gprovided lthe 'carbon dioxide..

content" of such gases is .low enough and i-f 'the temperatureis sufiiciently below the zinc :dew

point.`V vln `all/cases, the condensingf=eiiicier1cy Yis high, .and the exhaust .gas contains only -a relatively small percentageof luncondensed zinc, vand little .or no blue Apoi/vider is :otherwise formed. lWhile the upwardly-directed @and splashing. sheets Ior showers of molteny .zinc are preferably stage of its passagethrough the chamber, by rotation of the rotor` i6 clockwise as viewed in Fig. 1, the rotor may be arranged to throw the splashing sheets or showers of molten zinc into the gas stream at any stage in its passage through the condensing chamber.

We claim:

1. The method of condensing zinc vapor which comprises passing a gaseous stream containing zinc vapor through a condensing chamber having a body of molten zinc in the bottom thereof, and hurling by centrifugal action a substantially continuous and upwardlydirected shower of said molten zinc of suc-h violence as to provide by itself and by its splashing against the conning upper portion of the chamber turbulent sheet-like showers of molten zinc through which the gaseous stream passes.

2. The method of condensing zinc vapor which comprises passing a gaseous stream containing zinc vapor through a condensing chamber having a body of molten zinc in the bottom thereof, and picking up in rapid succession from said body of molten zinc small amounts thereof and hurling by centrifugal force said small amounts oi molten zinc upwardly in the condensing chamber and against the walls thereof and thereby pid viding sheet-like showers of molten zinc through which the gaseous stream passes.

ERWIN C. HANDWERK.

GEORGE T. MAHLER.

HARRY C. HAUPT.

REFERENCES CITED The following references are of record in the le of this patent:

UNITED STATES PATENTS Number Name Date 1,884,088 Miller Got. 25, 1932 2,348,194 Crane et al May 9, 1944 FOREIGN PATENTS Number Country Date 55,473 Sweden May 24, 1922

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