US1219193A - Condenser in the metallurgy of zinc. - Google Patents

Description

J. THOMSON & F. A. J. FITZ GERALD.

coNnENsER IN THE METALLURGY oF zlNc.

APPLICATION FILED JUNE 2l. i916.

Patented Mar. 13, 1917.

2 SHEES-SHEET I.

I. THOMSON & F. A. I. FITZ GERALD.

CONDENSER IN THE NIETALLURGY 0F ZINC.

APPLICATION FILED JUNE 2l 1916.

Patented Mar. 13, 1917.

2 SHEETS-SHEET 2.

c nue v1v Lord UNTTED STATES PATENT OEEIOE.

JOHN THOMSON, F NEW YORK, AND FRANCIS A. J'. FITZ GERALD, OF NIAGARA FALLS,

NEW YORK, A-SSIGNORS TO JOHN THOMSON JERSEY, A CORPORATION OF NEW JERSEY.

PRESS COMPANY, OF JERSEY CITY, NEW

CONDEN SER IN THE METALLURGY OF ZINC.

To all whom z' may concern.'

Be it known that we, JOHN THOMPSON and FRANOISA. J. F rrz GERALD, citizens ofl the United States, and residents, respectively, of the borough of Manhattan, city of New York, county and State of New York, and of Niagara Falls, county of Niagara, State of New York, have invented certain new and useful Improvements in Condensers in the Metallurgy of Zinc, of which the following is a specification, reference being made to the accompanying drawings, forming a part hereof.

This invention relates to the metallurgy of zinc and particularly vpertains to 'condensers which are used in conjunction with or which constitute a part of an electric furnace that is adapted for purifying lowgrade spelter by the distillation thereof. Some of the objects of the invention are to obtain a high capacity` -in an integral condensing unit, to condense zinc-fume to liquid metal and to separately precipitate cadmium-fume, when such is present, in the form of an isolated powder, or as a concentrate with zinc-dust.

In said drawings which present a preferred embodiment of the invention,

Figure l is a vertical, longitudinal center section and elevation of a brick housing having the condenser mounted therein, all being at the right-hand side of an indicated electric furnace, A, in which the fume is produced.

Fig. 2 is an end elevation of the aforesaid housing showing a portion of the condensing apparatus.

Fig. 3 is a horizontal center section of the liquidcondenser and the precipitator, and is a view taken as on the lines B and C of Figs. l and 4, or as viewed from above with respect to Fig. 1.

Fig. 4 is a half center section, taken as on the line D, and a half side elevation looking at the condenser in the direction indicated by arrow E of Fig. 3; and

Specification of LettersrPatent. Patented Mar. 13, 1917, Appneation filed June 21, 191e.

Serial No. 104,837.

ers, which receive zinc-fume from a single.

source of supply, is much more dilicult than when the condenser itself is a self-contained unit.

In an electric furnace which can distil zinc at the rate of, say, one hundred and twenty pounds an hour, this means that about twelve cubic feet of fume per minute has to be dealt with. The thermal duty is probably quite as severe to emit as to receive heat-units; hence, in a structure having an adequate volumetric capacity, made of material immune to air-burning and wholly free from checks or cracks, the difficulty of construction is pronounced.

The practice, hitherto, has been to utilize the condenser itself as a container of the condensed liquid metal; which, from time to time, is partially or wholly tapped olf.

Vhen zinc is contaminated with cadmium, which is usually in the proportion of less than one per centum, it can be more orless vextracted by fractional distillation, which requires a furnace of special construction; by fractional condensation, which produces a minimum by-product of zinc high in cadmium, and by burning at the condenser-vent, which entails its loss as well as a certain amount of entrainedzinc-fume.

A brief analysis of the procedure and what is to be accomplished will now be given in that this will serve to clarify the following detail description. If there is no cadmium to be dealt with, all of the zincfume is to be condensed in a casing from which the hot liquid metal escapes as and when produced and it is then collected in a separate container from which it is intermittently withdrawn.

i' Theoretically, zinc and cadmium begin to slowly condense at about, or somewhat below, their respective conventional boiling points, 930c and 780 C.; but the'rate of liquefaction proceeds progressively anr rapidly with fall of temperature and in contact withan adequate cealescing surface. The conventional chilling, or freezing points are 4190 for zinc and 320o C. for cadmium. Y

Normally, the amount of the cadmium content in spelter, such as would usually be distilled, ranges from 0.20 to 0.50 per cent.; hence its volume, as fume, would range but from about 25 to 50 cubic feet in a ton of zinc. I

If cadmium fume is mingled with the zinc-fume, then the latter is not to be completely condensed, the thermicity being so controlled that the maj or portion of the condensation is effected between a relatively short range in temperature, 900 C., as a maximum falling to about 7 500 to 7 00o as mini-mums.

Thus, the residual fume remaining in the condenser will. be a gaseous concentrate, high in cadmium. For the present purpose, let it be assumed that it is half and half. This low-temperature fume-concentrate is then to be conducted to a chilling prolong wherein it is precipitated as powder and more or less automatically7 separated in subchambers, ranging from zinc-dust, to zinc-cadmium dust, to cadmium-dust. y

The means for realizing the foregoing re sults may be vvariously modified and arranged accor-ding to existing circumstances;

but those which will nowlbe describedhave proven effective and will serve as an example based upon practical performance.

The dominant elements c-f the system are as follows: A, denotes a furnace in which the fume is produced and vfrom whence it passes, as through a throat or conduit I te a condenser J mounted in a brick housing K. L is the liquid zinc receiver having a drawoff spout 'M, and N is the dust or powder precipitatcr. p

rIhe condenser may be readily and inexpensively formed from two shallow pans, 6, 7, each a duplicate of the other, having flanges, 8, '9, which may be availed of for the application of suitable clamps, the latter not being shown. One end of each pan is partially removed so that, when the two are set together, they form a port 10 whose area approximates that of the furnace-throat.

Vithin the casing are a series of staggered bafiie-plates, as 12, conveniently sustained by being strung upon a central rod, 13, whereby the fume is caused to travel in a sinuous course, as shown by arrows a, and

`large `area; but, 1n the present case,

say from about' to also impinge upon a coalescing surface4 of these featuresare not introduced as the subjectmat-er to serve the basis for specific claims. rThe condenser, when thus assembled, is cemented to the throat, as at 14, and is setin the briclnhousing'with sharp down-slope therefrom, or'as shown at a decline of about 10, being supported as at 15, 16, Fig. 1.

At the end of and beneath the condenser, farthest from the throat, the extraneous zinc receptacle is set, which may be, as shown, an ordinary crucible provided with a tap-hole, 17. The interior of the condenser l is connected to the receptacle by a hole, 18,

formed in the bottom pan.

By a proper disposal of the baffie-plates and having regard to their number, and by controlling the temperature and the volume of the entering fume, the condensation may be distributed through a maj or portion or all of the condenser-casing, or a certain residualof fume may be taken ofi' through a vent. f

Due to the sharp decline of the condenser, the liquefied metal trickles down the bafiieplates; and runs rapidly along the bottom and thence passes down through the opening in the casing, as and when condensed, to the underlying receptacle, as arrow v, Fig. 1.

The consequences are that the temperature of the condenser casing can readily be maintained, for any given rate of fume-volume, with the utmost uniformity, and should a fissure develop in any portion of the casing, or at the Harige-j oint, the escaping fume will burn to Zn() and automatically seal the leak. In other words, the casing is solely a fume container.

The brick housing is provided with horizontal flues, as 18, 19; vertical connecting fines, as 20, and side openings, as 21. The zinc receptacle is preferably set on a spaced, brick grid, indicated by 22, and there is an opening, 23, in the front wall through which it may be conveniently inserted or removed, without disturbing the condenser casin its joint at the condenser, being cemente as at 2 The objects of the flues and side-openings are, firstly, for convenience in preliminarily heating the condenser and receptacle, as by means of charcoal fires in the flue 19 and on the hearth, 25, and to thereafter utilize them for controlling the rate of radiation by flow of cold air therethrough. These can be used simultaneously or separately, as desired. An additional control of the condenser temperature is at the top, as by partially or wholly removing, or by adding bricks upon, the cover-plates, 26. In this wise, the rate of heat-radiation is under such complete control it can be said that essentially any zone of the condenser-casing may be uniformly held to within a few degrees of a desired temperature. Moreover, such control may be readily attained and when'established little or no further attention is necessary. The concluding cordinating features of theinvention will now' be described in detail.

The prolong or anterior chamber" member, as depicted 1n the drawmgs, 1s formed of a metal cylinder, 27, open at one end a-nd inclosed by. an integral head, 27, at the other, on which is a bored spud, 28, adapted to be inserted in a side-opening in one of the pans, preferably at the'termination of the sinuous fume-circuit. The main body of the prolong projects horizontally intol Now, bearing in mind that any desired aliquot part of the condenser-fume, which, with respect to its entering temperature at the throat, will be relatively cool, can be retained as a residuum (in practice, say, about one or two per cent.) and will thence flow into the prolong, the consequence is that it is chilled in the air-cooled'cylinder and by impingement upon the bathe-plates being precipitated as a powder, fw, see Fig.'

Moreover, as the chilling, or freezing, temperature of cadmium is about 100 C., below that of zinc, there will be an accumulation of dust in the spaces between the wings of the baffle-plates becoming pro- .gressively higher in cadmium' toward the far end of the cylinder, or as from n to 7', to s, to to z. Then by carefully withdrawing the central rod with its attached plates, and collecting the powder from each compartment a separation of the different powders' or concentrates thereof can be effected.

If there is no cadmium in the spelter, the prolong needs simply be removed, in which instance the usual circulating, or name-vent.,I

would be in the condenser casing; but if powder is being precipitated the vent would be in the far end of the prolong, as at 35, Fig. 5.

Obviously, the prolong may readily be water-cooled, if a high rate of precipitation is desired, as by means of an encircling pipecoil. So, too, as has` been previously proposed, a further control of the rate of flow ,of fume` therein can be, effected by means of suction, preferably produced by aneinducing flow of air undermoderate pressure applied at the far end of the prolong.

To indicate the commercial practicability of this invention it can be stated that a single condenser, having a depth of 6 inches .with a breadth and width of about 28 X 48 inches, has 4condensed over one and a half tons of liquid zinc in 24 hours, and that a powder concentrate has been precipitated 4containing nearly 29 per cent. of cadmium to^71 per cent. of zinc from spelter which originally contained less than fifteen hundredths of one per cent., equivalent to three pounds in a ton of zinc.

What is claimed is:

1. In the metallurgy of zinc, a condenser, set at a decline from the source of fumesupply and in which liquid metal is produced but not retained, combined with a separate underlying zinc receptacle disposed in such manner that it can be removed without disturbing the said condenser.

' 2. In the metallurgy of zinc, a condenser in which zinc fume is condensed, the resulting liquefied zinc not being retained in the condenser, an underlying container for receiving said liquefied zinc and a'brick-hous- 4ing provided with side-openings and horizontal flues, whereby extraneous heat may -be applied simultaneously or separately either to the said condenser or the container. 3. In the metallurgy of zinc, a condenser in which fume is condensed but not retained,

an underlying container for receiving the liquefied zinc and a brick-housing provided with horizontal and connecting vertical viues, openings in the side-wallsand a sectional removable cover, whereby thearate of heat-radiation from the condenser may be controlled at all portions of its surface and sufiicient heat be retained in the container 'to prevent the liquid metal therein from solidifying.

4. In the metallurgy of zine, a furnace for producing fume by distillation, a con` denser in which fume is condensed but not retained as liquid metal; and means for so controlling the flow of fume therethrough and its rate of heat-emissivity that any desired aliquot portion of the entering fume reaches y the far end of said condenser at a` definite diminished temperature. s

5. In the metallurgy of zinc, a furnace for producing fume by distillation, a condenser in whlch fume is condensed but not retained as liquid metal, and means for so tially all of the entering zinc-fume is condensed when the fall of temperature will have reached 7 50 to 700o O.

6. Inl the metallurgy of zinc, a furnace for producing fume by distillation, a ccndenser 1n which a major portion of the fume is 'condensed to liquid metal and attached dust-precipitating prolong provided with winged baille-plates, forming sub-compartments along the bottom thereof, whereby progressive concentrations of zinc-cadmium or cadmium-zinc powder are collected and may be separately removed.

This specification signed and witnessed the fourteenth day of June, A. D.v 1916, in the city of New York, borough of Manhattan, State of New York, by-

JOHN THOMSON, and the 16l day of June, A. D. 1916, at Niaoara Falls, county of Niagara and' State of New York, Icy- FRANCIS A. J. FITZ GERALD. Nitnesses for John Thomson:

W. C. MAneEsom M. F. KEATING. Witnesses for Francis A. J'. Fitz Gerald:

R. H. WARREN, H. W. CLARK.

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