US2440374A - Smelting furnace - Google Patents

Description

SIELTING FUBNACE Filed Sept. 16, 1943 3 Sheets-Sheet 2 NJA April 27, 1948. L. s. LONGENECKER 2,440,374

SMELTING FUFNACE Filed sept. 16, 194:5

3 Sheets-Sheet 5 Patented Apr. 27, 1948 UNITED STATES PATENT OFFICE IMIMM SMELTING FUBNACE Levi S. Longeneokm Mount Lebanon, Pn. Appllcatlon September 18, 1943, Scrl!! No. $02,581 Glalml. (Cl. 286-10) This invention relates to furnaces for smelting' such materials as copper and nickel and it relates more particularly to what are commonly termed reverberatory furnaces for smelting such materials.

In the present day commercial type furnaces used in smelting copper and nickel, all of the fuel enters the furnace chamber through burners located in the furnace back wall-the wall remote from the settling end of the furnace. These burners are placed in a row side by side, and either four, or six or more burners are used at present.

The material to be smelted is either dropped through pipes tted into fettling holes in the furnace roof to form side wall banks, or the material is introduced through openings in the sides of the furnace by means of screw devices or powerful plungers. In either case, the material to be smelted is entered adjacent the furnace side walls and extends throughout the length of the melting section which varies in length in dierent furnaces.

From the location of the material to be smelted and the position of the burners. it is apparent that the flames from the two outside burners in the row of burners-either four. six or more-are the only names that contact directly with this material. The ames from the intermediate burners-two, four or more as the case may be are projected into the furnace chamber above the pool of matte and slag located between the side wall banks. The names from these intermediate burners therefore do not contact with the side wall banks with maximum flame temperature.

Some present day reverberatory smelting furnaces run up to about 130 feet in length and have a width, between the side walls in the smelting portion of the furnace. of as much as 30 feet.

For some time, it has been my impression that the present back wall method of firing these long reverberatory furnaces (the present commercial method) involves a misappllcation of fuel, since the maior part of such fuel is burned completely out of contact with the material to be melted.

One object of this invention is to produce an improved reverberatory furnace for smelting material such as copper and nickel.

Another object is to produce a reverberatory smelting furnace in which the fuel is much more efilciently utilized than is done in present day commercial furnaces.

Another object is to produce a reverberatory smelting furnace in which. without any material increase in heat input, it is possible to maintain 2 a relatively high substantially constant flame temperature above and in contact with the material to be smelted throughout substantially the full length of that part of the furnace chamber extending from the furnace back wall to the exhaust duct, and at the same time maintain a relatively low exhaust gas temperature.

A further object is to produce a reverberatory smelting furnace in which it is possible to maintain a relatively high temperature in the settling chamber without adding any material amount of heat to the exhaust gases.

A further object is to produce a smelting furnace that has a greatly increased smelting capacity as compared with the present day commercially operating furnaces.

A still further object is to produce a reverberatory furnace for smelting such material as copper and nickel, in which it is possible to obtain lower metal values in the slag than in the present day commercial smelting furnaces.

These and other objects, I attain by means of the furnace described in the specification and illustrated in the drawings accompanying the same and forming part of this application.

In the drawings:

Figure i is a top plan view of a furnace embodying this invention in one of its forms. The furnace roof is omitted for the purpose of more clearly showing the side wail design, the location of the burners and the location of the f ettling holes with relation to the burners. While the fettllng holes are in the roof, which is omitted in this viewI their location with relation to the burners and side walls is indicated by circles. The approximate shape. location and length of the names is indicated. The furnace of this figure comprises three smelting zones arranged in end to end relation between the furnace back wall and the exhaust gas duct. In this form the side walls of each smelting sone converge from the inlet end of the zone to the outlet end thereof.

Fig. 2 is a view similar to Fig. l but of a modied form of furnace of this invention. In this form the side walls of the smelting zones, instead of converging, parallel the longitudinal center line of the furnace.

Fig. 3 is a sectional elevational view and closely approximates views taken along the longitudinal center of either Fig. l or 2.

Fig. 4 is a sectional view taken on line IV-IV of Fig. 1 and closely approximates a sectional view such as one taken on line Iva-Iva of Fig. 2; a dierence in width being the only variation.

Fig. 5 is a sectional view taken on line V-V 3 of Fig. and closely approximates a sectional view tak n on line Va-Va of Fig. 2 or line Vb-Vb of Fig. l, a difference in width being the only variation: and

Fig. 6 is a sectional view taken on line VI-VI of Fig. 2.

Each of the furnaces disclosed in Figs. 1 and 2 comprises three independently tired smelting zones arranged end to end between the furnace back wall and the exhaust duct. The burners project their ames adjacent and substantially parallel to the side walls.

The settling chamber is located beneath the exhaust duct and is independently ired by burners which extend through the furnace front wall.

The gases traversing the exhaust duct on their way to the waste heat boilers (not shown) are shielded from the heat in the settling chamber by a shadow wall which extends rearwardly from the furnace front wall above the settling chamber, and is of hollow construction capable of being air cooled.

In the form of Fig. 1, each furnace side Wall. extending from the furnace back wall I to end wall II of exhaust duct I2. is of more or less sawtooth shape in plan as shown in the drawings. This sawtooth shape provides longitudinally extending portions II. I4 and i! which. from their rear to their forward ends. converge toward the longitudinal center line of the furnace. The forward end of portion I3 is joined to the rear end of portion Il by a. wall portion I8 which is substantially perpendicular to both portions I3 and I4. The forward end of portion Il is joined to the rear end portion Il by a wall portion Il which is similar to wall portion I8 and is also substantially perpendicular to portions I4 and Il.

Back wall i0 of the furnace is formed of two angled portions Ia which join at the longitudinal center line of the furnace. Each portion Illa is substantially perpendicular to the adjacent side wall portion I3.

The smelting section of the furnace extends from back wall I0 to the inner ends of side wall portions I5. From here on to the furnace front wall I8, the side wall portions I5 are parallel and parallel the longitudinal center line of the furnace. t

End Wall II of the exhaust duct is located at the junction of side wall portions IE and i9. Rear wall of the settling chamber is located forwardly of end wall II of the exhaust duct. thus allowing the exhaust gases to bypass the settling chamber and rise directly into the exhaust duct. Exhaust duct I2 leads the exhaust gases to waste heat boilers (not shown) as is usual.

A shadow wall comprising a refractory roof portion 22, a refractory floor 23 and a refractory end wall 24 is supported independently of the furnace side walls by transversely extending structural members 25 which project beyond the side walls and are secured to the outside furnace steel structure. 'I'he shadow wall is adapted to be cooled by air circulated therethrough between the roof and floor portions. The shadow wall is so located as to shield the exhaust gases from the heat of the molten slag and matte within the settling chamber.

The furnace side Walls in the smelting section because of their sawtooth shape divide the smelting section into three smelting zones which I have numbered I. 2 and 2 and which are arranged in end to end relation between the furnace back wall and the exhaust duct.

Each of these zones is provided with two independent burners (one on each side) each of which is so constructed and arranged as to proiect a high temperature name substantially parallel to the adjacent side wall portion Il, Il or Il as the case may be.

' Burners 2l for zone I extend through openings in portions Ina of back wall I0. Burners 21 for zone 2 extend through openings in end wall portions IB of zone 2, while burners 28 for zone l extend through openings in end wall portions Il of such zone. These burners may be oi any desired type. but I prefer to use a sealed in burner of the type which produces a relatively short high intensity llame. At 22a, 21a and 28a I have attempted to illustrate the six flames Produced by such burners, and as will be seen. these llames are arranged in tandem relation but slightly offset.

The roof of the furnace is illustrated in Pigs. 3, 4, 5 and 6. This is of the suspended type as indicated in these figures and is preferably formed of interlocking tile or blocks.

The roof section 29 over zone I is flat throughout its major part, is stepped down at the sides as at 30 and at its forward end is provided with a downwardly extending knuckle-like projection Il. This downwardly extending knuckle and the converging side wall portions Il restrict the outlet to zone I and tend to improve its reverberatory characteristics lengthwise of the furnace.

In zone 2, the central portion 22 of the roof is fiat while the side portions 33 which are raised above the central portion connect with the central portion by downwardly inclined portions 24, and with the extreme side portions 35 which are narrow and flat, by means of downwardly inclined portions 28.

At the outlet end of zone 2, each fiat portion 33 (the roof portions above the flames) terminates in a downwardly extending knuckle-like portion 31. thus a roof pocket is formed above each burner flame. The central roof portion 32 of zone 2, as will be seen from Fig. 3, is slightly lower than roof portion 29 of zone I.

The roof over zone 2 is similar to that over zone 2 but its flat central portion 3B is slightly higher than the central portion 32 of zone 2. Zone 3 at its outlet end is provided with depending knuckle-like projection 38 corresponding to knuckles 3l at the outlet end 0i' each name pocket.

The products of combustion or exhaust gases from zone I mingle with the products of combustion in zone 2 and these combined gases, after passing below knuckle 31 at the exhaust end oi' zone 2 mingle with the products of combustion formed in zone 3.

Depending knuckle 39 at the exhaust end of zone 3, together with the converging wall portions I5 of such zone not only serves to reverberate heat waves back into the smelting section of the furnace but, constricting the outlet to the smelting section, tends to build up the pressure in such section. The same of course is true of zones I and 2. since the converging side walls and depending knuckles 3| and 21 of these zones reverberate heat waves back into each of these zones.

The incremental building up of the furnace pressure by the converging side walls of the zones and the depending knuckles increases the temperature adjacent the burners for the zones,

atacan thereby smoothing out, so to speak, the temperature gradient lengthwise of the furnace between back wall Iii and knuckle ll. This causes a sharp drop in the temperature gradient adjacent knuckle I! and insures that the exhaust gases will enter exhaust duct i2 at a relatively low temperature.

The fore bay, which includes settling zone or chamber 2l and the shadow wall, insures low metal values in the slag withdrawn from the settling chamber or zone. The slag and matte in the settling chamber may be withdrawn through separate openings as is now customary. Buch openings may either be in the settling chamber side walls or in its front wall.

-In order to maintain the material within the settling chamber at the proper temperature for efficient settling. one or more burners I are provided in the furnace front wall. The flame or flames from these burners are proiected between the top surface of the slag within the settling chamber and the under surface of iloor 2l of the shadow wall. These burners are operated independentiy of the smelting zone burners and may be of any type found most desirable for keeping the slag thin and liquid in order to effect good sepgration of slag and matte.

The roof section over each smelting zone is shown as provided with a series of aligned charging openings or fettling holes. The holes for zone i are numbered Il. those for zone 2 are numbered 42 and those for zone 3 are numbered Il. It will be seen that the two lines of charging openings of zone I which deposit material to be smelted along the side walls of such zone and thus form side wall banks, project a distance into zone 2, parallel with the charging openings 42 of such zone. It will also be noted that the line of charging openings oi' zone 2 projects a distance into zone I, paralleling charging openings I3 of such zone. These overlapping lines of charging openings form what may be termed double, or twopeaked, side wall banks as disclosed in Figs. 5 and 8 at 4I and 4l, thus increasing the area of the side wall banks with a corresponding reduction in width of the channel between the banks.

The side wall banks in zone I' are numbered 4t. and from Figs. 4, 5 and 6, it will be apparent that flames 26a, 21a and 22a of the different smelting zones contact and scrub the side wall banks throughout substantially their full length. For this reason, these dames are most effectively utilized. and it will be apparent that this effective utilization of these flames insures a sharp drop in the temperature gradient adjacent the inlet end of exhaust duct IZ--that end immediately adjacent roof knuckle 3l.

With sealed in burners, and roof knuckles which reflect the heat of flames back into the zones. charging openings or fettling holes may be employed in the roof adjacent the zone end walls in order to provide additional wall banks of material to be smelted. This not only increases the total bank area, but serves as a protection for the end walls as well. While these openings are not indicated, it will be apparent how the same may be located and utilized.

The form of Figure 2 In the form of Fig. 2 of the drawings. the side wall portions l1 of zone i, 4I of zone 2 and 49 of zone l are parallel, and parallel the longitudinal axis of the furnace.

The furnace back wall which is numbered 50 is perpendicular to side wall portions 41. End wall portions BI of zone 2 are perpendicular to side wall portions I1 and ll. Side wall portions I2 of zone I connect with side wall portions t8 of zone 2 by inclined portions l2.

In this form of the invention, the burners for zone 3 are numbered and extend through openings in end walls I4 of zone I. These burners direct their names Bla toward the furnace back wall En. In this form. the inner portions of the double peaked banks of material to be smelted in zone I are supplied through charging openings or fettling holes It which extend rearwardly from end walls t4.

It will be apparent from the drawings and the above description that zones 2 and I are succeeding zones of the series and that each succeeding zone is wider than the zone that precedes it, that is. zone 2 succeeds zone I which precedes it and zone 3 succeeds zone 2 which precedes it.

The inner side wall portions of the pockets formed in the roof sections of zones 2 and I in both forms of Figs. 1 and 2 reflect or reverberate heat from the flames located below such roof pockets to the side wall banks and thus increase the smelting effectiveness of the flames.

While the present day back wall tired type of smelting furnace has probably reached its ultimate length and capacity. `it is believed that it will be apparent that smelting furnaces employing the zoning feature of this invention can be made as long as desired and of as great capacity as desired. Any number of independently tlred smelting zones of the type of either form here disclosed can be employed without lowering the enlciency of the furnace. Available space for the furnace is the only size limiting factor.

Having thus described my invention, what I claim as new, and desire to secure by Letters Patent is:

l. In a smelting furnace, furnace side walls that are so constructed and arranged as to provide a number of smelting zones extending in end to end relation between the furnace back wall and the exhaust duct. with each succeeding zone of greater width than the zone that precedes it. and means for maintaining a substantially oonstant relatively high flame temperature along both furnace side walls throughout the combined length of such zones.

2. A smelting furnace provided with a settling chamber adjacent its front wall and which from the furnace back wall to such settling chamber is divided into a number of separately fired smelting zones of different widths; that adjacent the furnace back wall being narrowest, with each succeeding zone of greater width than the zone that precedes it.

3. A smelting furnace having a settling chamber adjacent the furnace front wall: at least one side wall which is formed with offset portions which provide successive smelting zones of different widths and which are so constructed and arranged that the zone adjacent the furnace back wall is the narrowest, the next zone is of greater width and the next zone of still greater width; a roof over such zones provided with material charging holes adjacent the furnace side walls, and means for independently firing each zone.

4. In a smelting furnace, a settling chamber adjacent the furnace front wall, means dividing the space between the furnace back wall and such settling chamber into a succession of separately fired zones with each succeeding zone of greater width than that of the zone that precedes it.

5. A smelting furnace having a settling chamber adjacent the furnace front wail: at least one side wall which is formed with odset portions which provide successive smelting sones of different widths and which are so constructed and arranged that the zone adjacent the furnace back wallisthenarrowest,thenextzoneisofgreater width and the next sone of still greater width, a roof over such zones provided with depending knuckles at the outlet to such zones and means for independently firing each zone.

6. A smelting furnace provided with a settling chamber adjacent its front or exhaust gas end, and which between its back wall and such settling chamber is divided into a number of smelting zones of different widths; the zone adjacent the furnace back wall being the narrowest. each succeeding sone being of greater width than the zone that precedes it; means for establishing on opposite sid of each succeeding zone overlapping banks of material to be smelted and means for independently firing such zones.

7. In a smelting furnace. at least two separately fired smelting zones of diil'erent widths extending lengthwise of the furnace between the furnace back wall and' the furnace exhaust duct; with each succeeding zone of greater width than the zone that precedes it.

8. A smelting furnace comprising at least two smelting zones of different widths arranged end to end between the furnace back wall and the furnace exhaust duct, a settling chamber adjacent such duct, a shadow wail arranged to shield the exhaust gases traversing such duct from the heat in the settling chamber and a pair of burners for each zone arranged to project heating names adjacent to and substantially paraileling the zone side walls.

9. A smelting furnace comprising a number of smelting zones of diiierent widths arranged end to end between the furnace back wall and the furnace exhaust duct. a settling chamber adjacent such duct. a shadow wall arranged to shield the exhaust gases traversing such duct from the heat in the settling chamber, a pair of burners for each sone arranged to project heating flames adjacent to and substantially paraiieling the zone side walls and independent means for supplying heat to the material in the settling chamber.

l0. In a smelting furnace having an exhaust duct adjacent its front wail and a settling zone below such duct, a shadow wall overlying such zone and arranged to serve as -a shield between such duct and such zone, and means dividing the furnace space between such duct and the furnace back wall into a number of longitudinally extending smelting zones of different widths; each succeeding zone having a greater width than the zone that precedes it.

l1. In a smelting furnace havingV` an exhaust duct adjacent its front wall and s. settling zone below such duct, a shadow wall overlying such zone and arranged to serve as a shield between such duct and such zone. means dividing the furnace space between such duct and the furnace back wall into a number of longitudinally extending melting zones of dierent widths; cach succeeding zone having a greater width than the zone that precedes it, and a pair of burners for each such zone with each pair so constructed and arranged as to project a pair of heating names adjacent the zone side walls and throughout substantially its full length whereby a substantially constant high flame temperature is malntained throughout the furnace from the back wall to such duct and a relatively low temperature is maintained within the exhaust duct.

12.1nasmelting furnacehavinganexhaust ductadjacentitsfrontendasettiingzonebelow such duct, a shadow wall shielding such duct from said settling sone, means dividing the space between the furnace back wall and said duct into a number of longitudinally extending melting zones of diiferent widths: each succeeding zone belngofgreaterwidththanthezonethatnrecedes it, means for directing a heating flame adjacent and substantially parallel to each zone side wail with each such flame maintained at top flame temperature throughout substantially the full length of each such zone and means for directing a heating iiame into the settling zone below said shadow wall.

13. In a smelting furnace. a series of smelting zones of different widths arranged end to end between the furnace back wall and the furnace exhaust duct with each such zone extending from side to side of the furnace and with each succeeding zone of the series of greater width than the zone that precedes it. a rpair of burners for each zone arranged to project heating flames adjacent to and substantially paralleling the zone side walls and a furnace roof provided with a pocket therein above each flame in each succeeding zone of the series.

14. A smelting furnace comprising a number of smelting zones of different widths arranged end to end between the furnace back wall and the furnace exhaust duct and a roof over such zones provided with a transversely extending downwardly projecting knuckle at the outlet end of each such zone.

15. In a smelting furnace. a series of smelting zones of diiferent widths arranged end to end. with each succeeding zone of the series of greater width than the zone that precedes it and with the side walls of each zone converging toward the longitudinal center line of the furnace.

16. In a smelting furnace, a series of separately fired smelting zones of different widths arranged in end to end relation between the furnace back wall and the exhaust duct. with each succeeding zone of greater width than the zone that precedes it. each zone having its greatest width at its entrance end and from such end decreasing in width to its exit end.

i7. In a smelting furnace, at least two separately fired smelting zones of different widths arranged in end to end relation between the furnace back wall and the exhaust duct with each succeeding zone of greater width than the zone that precedes it; the side walls of such zones being parallel and paralleling the longitudinal axis of the furnace; the burners in the smelting zones adjacent each exhaust duct being so arranged that the names therefrom are directed toward the furnace back wall.

18. A smelting furnace having a settlingchamber adjacent one end and between its opposite end and such settling chamber comprising a series of separately fired smelting zones arranged end to end. each succeeding zone of such series being of greater width and height than the zone that precedes it.

19. In a smelting furnace, a settling zone at one end, means dividing the space between the opposite end of the furnace and such settling zone into a series of smelting zones arranged in end to end relation, each succeeding smelting zone being of greater width and height than the zone LEVI B. IDNGENECKER.

REFERENCES cmm The following references are ot record in the 111e of this patent:

Certiiicate o! Correction remt. No. 2,440,314.

5 UNITED STATES PATENTS Number Name Date 278,279 Sackett May 22, 1803 1,021,144 Gordon Mar. 26, 1912 lo 1,607,854 Urquhart Nov. 23. 1928 1,729,408 Wasstai Sept. 24, 1029 2,006,001 Rowe June 25, 1980 April 27, 1948.'

LEVI S. LONGENECKER It is hereby certified that errors appear in the specification of the above numbered patent req correction as follows:

olumn 8, line 4, claim 12, after the word end inserti-zlnnr-lnine 58, claim 17, for zones reed zona; line 59, same claim, for each read the; and that the said Letters Patent should be read with these corrections therein that the same may conform to the record of the case in the Patent Signed and sealed this 22nd day of June, A. D. 1948.

THOMAS F. MURPHY,

Assistant Uommsassoner of Patente.

LEVI B. IDNG.

REFERENCES cmm The following references are ot record in the 111e of this patent:

Certiiicate o! Correction remt. No. 2,440,314.

5 UNITED STATES PATENTS Number Name Date 278,279 Sackett May 22, 1803 1,021,144 Gordon Mar. 26, 1912 lo 1,607,854 Urquhart Nov. 23. 1928 1,729,408 Wasstai Sept. 24, 1029 2,006,001 Rowe June 25, 1980 April 27, 1948.'

LEVI S. LONGENECKER It is hereby certified that errors appear in the specification of the above numbered patent req correction as follows:

olumn 8, line 4, claim 12, after the word end inserti-zlnnr-lnine 58, claim 17, for zones reed zona; line 59, same claim, for each read the; and that the said Letters Patent should be read with these corrections therein that the same may conform to the record of the case in the Patent Signed and sealed this 22nd day of June, A. D. 1948.

THOMAS F. MURPHY,

Assistant Uommsassoner of Patente.

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