US1895878A - Metallurgical furnace - Google Patents

Description

Jan- 31, 1933 E. H BUNCE ET AL 1,895,878 METALLURGICAL FURNACE i Filed Nov. l5, 1927 mi 2f ,2; L 2z INVENTOR Ear/ h1. Bur/1Q hYfl/y 7, Has lar-r1 ATTORNEYS Patented Jan. 31, 1933` j 4UNrrlazD dSTATI-:s

j L. EARL rr. BUNCE AND HARRY NL HASLAM, or' rALMERroN, .PENNSYLVANIA ASSIGORS To THE NEW JERSEY zINc COMPANY, or NEW YORK, N. yf, A, CORPORAT-IO ,OFNEW i JERSEY v METALLURGICAL FURNAcE,4 'n

Application med November 15,1927'.` seriaiNo. 233,352.

This. invention" relates to metallurgical furnaces and has for its object the provision,

. in al metallurgical furnace, of an improved Vdevice for blasting or blowing metallic vapor issuing from the furnace.

United StatesgPatentgNo. 1,594,000 de- :scribes yan improvedV metallurgical furnace the metallic vapor is derived fromV the smeltprovided witha blasting device for'intensifying theV oxidation of metallic vapor issuing from the furnace. The blasting device described in this patent comprises a blow `box from which relatively cool oxidizing gas, such as airfunder pressure, escapes through an annular slot in the form of a circumferential blast that completely involves the stream of metal vapor issuing from the furnace. This typeof blasting device, While entirely satisfactory with streams of metallicvapor such as derived from the volatilizationof metal,

-does not.0perate with complete satisfaction upon vapor streams of relatively large sectional area such as derived from the smelting of ore. The stream of vapor derivedlfroln the volatilization of metal is highly concentrated'and hence is usually of relatively small sectional area. On the other hand, when ing of ore, it is diluted, usually with lcarbon monoxide gas, and furthermore the furnacing conditions usually preclude the building up within the furnace of any substantial gas j pressure. Hence, the gas outletsmust be rel,-A

atively large in sectional area,vv as compared with the gas outlets in a metal volatilizing furnace. The circumferential sheet of blast- .ing gas, such as produced by the device specifically described in the aforementioned patent, when directed against a vapor stream of relatively large sectional area tends to'develop into a swirling, rising shell of oxidizing gas which envelops, but does, not always Apromptly and completely penetrate, l the stream of vapors issuing lfrom thefurnace.

The present invention aims to provide an improved blasting device particularly adapty ed for use Witha metallurgical furnace in which the metallic vapor is derived from the smelting of ore. The invention is partcula-'n ly applicable to zinc oxide furnaces of the Wetherill grate type, whether of the station-- plicable for the production of ving, in Which-,

delivers fuel briquettes onto the, traveling,

ary or traveling grate forms. `While the invention may be applied y with advantage Wherever it is desired to blast or 4blow; al stream of metallicvapor, it is peculiarly ap- 4 j `zinc. ,oxide in furnaces of the Wetherill type.

v- The improved blastingdevice ofthe invention, in its preferred form, comprises va tubular gas compartment, conveniently of; circular section, adapted to rest upon the top 'or roof of the furnace and to surroundthe stream of vaporsissuing fromthegas outletin the furnaceroof. The inside wall of the tubular gas compartmentris providedwitha multiplicitv of per'forationsfor small openings adapted to direct, at anfappropriate angle, a substantially continuous Ibut individually separated ,series of gas jets r:against the stream ofvapors issuingfromV thejfurnacel Stood from the following description, taken in conjunctionwith F'g. 1,' i's aside elevation, partlyin section# Vof a `inetalluriginal furnace Ofl the Wetherill grate theinvention. 5 p 2is a top plan, partly'in section,- of the furnace ofFigl.v ,Y

3yis anfenlarged plan of the blasting elements shown in Figs. 1 and 2; and f ype embodying lthe improvements of soy The novel features of ,the improvedV blast- 70 n Ving device V,of the invention willbe best underthe accompanying ydraw- K Fig. 4 is a sectionalfelevation taken onithe f section line of Figli.;y e,

The furancelO illustrated in the drawing is "a Wetherill'furnacefof the traveling` grate type, particularly adapted :for the production of zinc oxide direct from ore. ,'The furnace has a moving perforated gratell, of the endlessV conveyor type, adaptedt'o advance the'. charge ,supportedV thereby througha coal ignition chamber 12 and then 'through a res -flucing and volatilizin'g chamber 13. Arhopperl'fl 'at'the charging end-'of the furnace vgrate and these briquettes arelfspreadto an A hopper 18 isprovided adjacent the-coal ignition chamber; between bulkheads or partitions 19 and 20 for the introduction of the metalliferous charge upon the ignited bed of fuel briquettes. This charge is preferably in lthe formof briquettes, such for example as a briquetted mixture of zinciferous and carbonaceous materlals.

The reducing and volatilizing chambferil I Y is provided with gas outlets 21, in the roof of the furnace structure, Vfor the escape of the -gaseousproducts'of the smelting or reducing operation. Down-legs 22, usually equipped with peep-holes at their lower ends, rest upon stand-pipe castings 23 located over the outlets 21. While the furnace shown inthe accompanying drawing has a separate and inde-V pendent down-leg'22 for each `gas outlet-21, all ofthe gas outlets 21, particularly in a furnace of the traveling grate type,lmay open Y into a common hood vor manifold havingy a single ydown-leg. f r l The improved'blasting device of the invention is mounted Onthe roof of theffurnace 'above each of the gas Voutlets 21. As illustrated in thel drawing, the blasting device, comprises a hollow tubular member 27 havingv a lateral hollow extension 27 adapted to be Vconnected to the air. or other oxidizing gas main 24 through a pipe 25 provided with a damper or valve 26. TheV gas main 24; is

preferably sufficiently elevated, orY spaced, from the. furnace proper, as shown in the drawinggso that airpassingtherethrough is y'substantially not preheated. The pipe`25 preferably extends downwardly vfrom thegas main 24m such a Way. as showmthat it will be exposed to a minimum of vheat coming from tlmfurnacev walls.A It is aimed to per.- y mit thepassage of. air through thegas main a multiplicity oflperforatious or small, holes .28, through which gasfescapes, from the gas compartmentfprovidedby thehollow interior y Y .v c, l

Y Y Vlic VZinc is volatilized. The furnaceals closed L as tightly as practicable to exclude ther-adof` the tubular member. M Y

The holes28 arepreferably drilled through the wall of thetuhular; member 27., These holes.. are arranged as a continuous series in the form of a circle. Adjacent holes are sufliciently spaced from .one another so that the; streams or jetsof gas issuing from. each hole are substantiallylseparate and'independ- Sent, although these separate gasfjets taken in their entirety-completely envelope' the stream of vapors;v issi-ng fronr the outlets 21.

Te this end the wallthickness ofthe tubularV 'dischargedthrough the holes 28'. lThe holes Y are moreover arranged to direct the enveloping gasfjets against the vapor'stream at an appropriateangle', while each hole is l directed towards the ycenter axis of the tubular.

member.

Merely by way of example, we will describe twenty-eightinches. Thewallthickness ofk the member` was one-halfinch, -s'othat the circular section of the hollow interior of the The member was four inches in diameter.

holes-28V were three-eighths inch in diameter weredrilledl at ani-angle of-Aaboutf? with.

respect to a horizontal-plane." It.will,'"of course, be understoodl that the dimensionsl of the blasting device, including the .number of perforationsV or: holes, their size and 4angle of f vat f inclinationswill depend uponthepressure and volume of the issuingl streamfof vapors, .the dimensions and suction draftuoftheld'ownlegs and' the pressure and quantityofblasting gas tobe employed.I Simple-.investigations will serve to adequately determine the optimum dimensions for 'any Aparticular'fur naclfng operation.- v

' The operation `of the apparatus hereinbefore described while producing zinc 'oxide from a briquettedcharge is as follows: `l

Suitable fuel briquet-tes are' fed' into ythe hopper 14j vv As Vthe traveling grate 11 con- Veys a layer 'of' these .briquettes through the ignition chamber 12, the `briquette'es are -ignited. VAlayer of' briquetted zinciferous-and carbonaceous Vmaterials is deposited Vfromy the hop-per 18-onto thev ignited fuel briquettes. Combustion and ,smelting ofth'ewbriquettqes are aided by ablast of air* passing up vthrough 'the perforated grate 11. f -lrq As the "highly heated briquetted' `change passes. through the chamber v13,;hef'zinefermipounds `are reduced and the resulting metal- `vthe chamber 13 flowy from the Vvfurnace throughthe outlets 21,'and are-"subjected to the blasting action of the relatively @mi on:

d izing gasdischarged from the Ablasting de- Vlce. Y,

The strengthand volumerofthe blast isin part controlled by the damper'si261v Itl of course preferred Ythat the fari-{ (not. 1

supplying'the airto the main feeder", pipe be operatedat apredeterminedspeedsothat a substantially uniform supply of air may be passed to the blasting elements.

The air forced into the member 27 circulates within the hollow compartment thereof and is made to issue through the multiplicity of holes 28. This air is supplied under suflicient pressure to make individual streamlets of air pass through the holes. .As the stream of zinc vapor issues from the outlet 2l, it is met by these numerous streamlets of air. Each streamlet of air tends to penetrate the moving stream of Zinc vapor to its very center. Since the whole stream of zinc Vapor is promptly and directly penetrated with these numerous streamlets of air, the vapor is very promptly oxidized togzinc oxide.

The volume and draft of air is sufiicient to almost instantaneously cool down the Zinc oxide particles before they have a chance to coalesce. In this manner particle growth due to heat is substantially inhibited. means that all of the zinc vapors are quickly contacted with air to form Zinc oxideparticles,'which are almost instantaneously cooled. This results in a zinc oxide pigment of exceedingly fine and uniform particle size.

While the foregoing represents an illustrative working exampleof the present invention, it is to be understood that the principles of the invention may be readily practiced in other ways. Any stream of zinc or other metallic vapors, no matter how obtained, may be oxidized by the method and apparatus contemplated. For example, the stream of metallic vapors may be obtained directly from the smelting of ores, or from the melting and volatilization of metal. Moreover, the stream of metallic vapors may be circular, oval, square, or ,rectangular in section, and blasting elements of appropriate size and shape may be provided to operate in connection with such streams of vapors.

The improved blasting device of the invention is readily and convenientlymounte-d in position on the furnace. The angle of inclination of the perforations is easily controlled to give the optimumangle of blasting against the issuing stream of metallic vapor. Moreover, theV construction and arrangement of the blasting device is such that the walls of the outlets 21 are not subjected to undesirable cooling with the consequent formation of troublesome accretions, and such accretions as do form about the blasting lelement are removed from time to time without difliculty and at slight labor expense.

We claim l. A metallurgical furnace comprising a zinc reduction chamber, a vapor conduit communicating with said reduction chamber, an air discharging device operatively associated with and surrounding the exit end of said conduit, said air discharging device comprising a hollow member having its wall perforated with a multiplicityl ofholes adapted This to direct a multiplicity of streams of air t0- wards zinc vapor issuing from said conduit.v

2. A zinc metallurgical'furnace comprising a reduction chamber, a vapor conduit communicating with said reduction chamber, an air discharging device operatively associated with said conduit, an air supply conduit communicating with said air discharging device, said air supply conduit being spaced away from the normally hot'furnace walls so that air passed therethrough will not be materially preheated in transit, said air discharging device comprising a hollow member having its wall perforated with 'a multi-l plicity of holes adapted to direct a multiplicity of. streams of air directly into zinc vapor issuing from said vapor conduit.

aoV

3. A zinc metallurgical furnace of the VVetherill grate type for the manufactureof zinc oxide comprising a reduction chamber defined by a perforated grate adapted to supv porta charge ofY zinciferous material and carbonaceous reducing agent and surrounding furnace walls sealed against undue admission of outside air and furnace arch, azinc vapor-gas discharge conduit communicating with said reduction chamber through the arch thereof, an air-discharging device-,op-

eratively associated with said conduit, said air. discharging device comprising a hollow member having its wall perforated with a multiplicity of holes adapted to direct a multiplicity of jets of air directly into zinc vapor issuing from lsaid conduit.

4. A zinc metallurgical furnace according to the preceding claim, in which an air supply conduit connects with said air discharging device, the air supply conduit being spaced awayV from the normally lhot furnace walls so that air passed therethrough will knot be materially heated in transit.

5. The combination with a z1nc metallurgi- Y cal furnace of the Wetherill grate type for the tures.

' EARLH. BUNCE. Y v lHARRY M. HASLAM.l

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