US2534825A - Smelting furnace - Google Patents

Description

Dec. 19, 1950 L. s. LONGENECKER SMELTING FURNACE 5 Sheets-Sheet 1 Original Filed Sept. 16, 1943 om m m NEON v N wtoN \lall III III l Dec. 19, 1950 L. s. LONGENECKER SMELTING FURNACE 3 Sheets-Sheet 2 Original Filed Sept. 16, 1943 n u o 5 G L. S. LONGENECKER Dec. 19, 1950 SMELTING FURNACE 3 Sheets-Sheet 5 Original Filed Sept. 16, 1945 Patented Dec. 19, 1950 USED STATES ENT OFFICE Original application September 16, 1943, Serial No. 502,581. Divided and this application November 23, 1945, Serial No. 630,265

3 Claims.

This invention relates to furnaces for smelting such materials as copper and nickel, more particularly to what are commonly termed reverberatory furnaces for smelting such materials and is a division of my copending application Serial No. 502.531. filed September 16, 1943, now Patent No. 2,440,374, issued April 27, 1948.

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 fitted 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 different 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 burnerseither four, six or more are the only flames that contact directly with this material. The flames from the intermediate burnerstwo, 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 flames 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 feet.

For some time, it has been my impression that the present back wall method of firing these long reverberator furnaces (the present commercial method) involves a misapplication of fuel, since the major 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 provide 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.

Another 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.

Another object is to provide means for reducing the temperature of the gases passing through the exhaust duct of a reverberatory smelting furnace.

A further object is to provide means for effectively shielding the exhaust gases from the heat of the settling chamber of a reverberatory smelting furnace.

A further object is to produce an effective shield between the settling chamber and the exhaust duct of a reverberatory smelting furnace.

A still further object is to produce an improved settling chamber for reverberatory 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 1 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 wall design, the location of the burners and the location of the fettling holes with relation to the burners. While the fettling holes are in the roof, Which is omitted in this view, their location with relation to the burners and side walls is indicated by circles. The approximate shape, location and length of the flames 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 zone converge from the inlet end of the zone to the outlet end thereof.

Fig. 2 is a vi w similar to Fig. 1 but of a modified 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 Figs. 1 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 Ivar-I la of Fig. 2; a difference in width being the only variation.

Fig. 5 is a sectional view taken on line V-V of Fig. l and closelyapproximates a sectional view taken on line Va--Va of Fig. 2 or line 3 VbVb of Fig. 1, a difference in width being the only variation; and

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

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

The settlin chamber is located beneath the exhaust duct and its temperature is independently controlled.

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 chamher, 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 it to end wall H of exhaust duct 62, is of more or less sawtooth shape in plan as shown in the drawings. This sawtooth shape provides longitudinally extending portions i3, i5 and it which, from their rear to their forward ends, converge toward the longitudinal center line of the furnace. The forward end of portion 13 is joined to the rear end of portion [4 by a wall portion l6 which is substantially perpendicular to both portions l3 and Id. The forward end of portion 14 is joined to the rear end portion H: by a wall portion i? which is similar to wall portion l6 and is also substantially perpendicular to portions l4 and 15.

Back wall it of the furnace is formed of two angled portions lBa which join at the longitudinal center line of the furnace. Each portion lBa is substantially perpendicular to the adjacent side wall portion :3.

The smelting section of the furnace extends from back wall 59 to the inner ends of side wall portions l5. From here on to the furnace front wall IS, the side wall portions iii are parallel and parallel the longitudinal center line of the furnace.

End wall ll of the exhaust duct is located at the junction of side wall portions l5 and I9, while the rear wall of the settling chamber, which is numbered 20, is located forwardly of end wall II.

A shadow wall extends from the front end of the furnace to a point adjacent rear wall 20 of the settling chamber. This shadow wall overlies the settling chamber, causes the exhaust gases to bypass the settling chamber and shields such gases from the heat of the molten slag and matte with'n the settling chamber.

This shadow wall comprises a refractory roof portion 22, a refractory fioor 23 and a refractory end wall 24 and 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. The shadow wall is adapted to be cooled by air circulated therethrough between the roof and floor portions.

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 l, 2 and 3 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 inc: r Lu 4 dependent burners (one for each side) each of which is so constructed and arranged as to project a high temperature flame substantially parallel to the adjacent side wall portion l3, M or 5 as the case may be.

Burners 26 for zone I extend through openings in portions 10a of back wall i9. Burners 2'! for zone 2 extend through openings in end wall portions E6 of zone 2, while burners 28 for zone 3 extend through openings in end wall portions ll of such zone. These burners may be of any desired type, but I prefer to use a sealed in burner of the type which produces a relatively short high intensity flame. At 25a, 21a and 28a I have attempted to illustrate the six flames produced by such burners, and as will be seen, these flames are arranged in tandem relation but slightly olfset.

The roof of the furnace is illustrated in Figs. 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 l is flat throughout its major part, is stepped down at the sides as at 39 and at its forward end is provided with a downwardly extending knuckle-like projection 3|. This downwardly extending knuckle and the converging side wall portions l3 restrict the outlet of zone I and tend to improve its reverberatory characteristics.

In zone the central portion 32 of the roof is flat while the side portions 33 which are raised above the central portion connect with the central portion by downwardly inclined portions 34,

. and with the extreme side portions 35 which are narrow and flat, by means of downwardly inclined portions 35.

At the outlet end of zone 2, each 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 is similar to that over zone 2 but its fiat central portion 38 is slightly higher than the central portion 32 of zone Zone 3 at its outlet end is provided with depending knuckle-like projection 39 corresponding to knuckles 3'! at the outlet end of 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 3? at the exhaust end of 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 revcrberate 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 secti A. The same of course is true of zones 1 and since the converging side walls and depending knuckles 3i and 3? of these zones reverberate heat waves back into each. of these zones.

ihe 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, thereby smoothing out, so to speak, the temperature gradient lengthwise of the furnace between back wall It and knuckle 39. This causes a sharp drop in the temperature gradient adjacent knuckle 39 and insure that the exhaust gases will enter exhaust duct l2 at.a relatively low temperature.

The fore bay, which includes settling zone or chamber 2! 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. Such 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 efiicient settling, one or more burners to are provided in the furnace front wall. The flame or flames from these burners are projected between the top surface of the slag within the settling chamber and the under surface of floor 23 of the shadow wall. These burners are operated independently of the smelting zone burners and may be of any type found most desirable for keeping the slag thin and liquid in order to eifect good separation 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 5 are numbered 5!, those for zone 2 are numbered 32 and those for zone 3 are numbered 43. 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 of zone 2 projects a distance into zone 3, paralleling charging openings Q3 of such zone. These overlapping lines of charging openings form what may be termed double, or two-peaked, side wall banks as disclosed in Figs. 5 and 6 at Ali and i5, 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 1 are numbered 46, and from Figs. 4:, 5 and 6, it will be apparent that flames 26a, Zia and 28a of the different smelting zones contact and scrub the side wall banks throughout substantially their full length. For this reason, these flames 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 l2--that end immediately adjacent roof knuckle 39.

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 4'5 of zone 9, 38 of zone 2 and 49 of zone 3 are parallel, and parallel the longitudinal axis of the furnace.

The furnace back wall which i numbered 55 is perpendicular to side wall portions 47. End wall portions 59 of zone 2 are perpendicular to side wall portions 4'! and 48. Side wall portions 6. 49 of zone 3 connect with side wall portions 48 of zone 2 by inclined portions 52.

In this form of the invention, the burners for zone 3 are numbered 53 and extend through openings in end walls as of zone 3. These burners direct thei flames 53a toward the furnace back wall 59. In this form, the inner portions of the double peaked banks of material to be smelted in zone 3 are supplied through charging openings or fettling holes 55 which extend rearwardly from end walls 54.

It will be apparent from the drawings and the above description that zones 2 and 3 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 precede it.

The inner side wall portions of the pockets formed in the roof sections of zones 2 and 3 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 fired 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 fired smelting zones of the type of either form here disclosed can be employed without lowering the efiiciency 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:

1. In a reverberatory smelting furnace having an exhaust duct adjacent its front wall, a settling chamber below such duct, means for supplying heat to the material in the settling chamber, a wall extending rearwardly from the furnace front wall, overlying such chamber and arranged to serve as a shield between such duct and such chamber, a smelting section between such duct and the furnace back wall and a roof over such section having a depending knuckle at the outlet end of such section for constricting the outlet from the smelting section to the settling chamber.

2. In a reverberatory smelting furnace having its exhaust duct adjacent its front end, a settling zone below such duct, air cooled refractory means shielding such duct from such settling zone, a smelting section extending from the furnace back wall to such duct, a suspended roof over such smelting section provided with a depending knuckle at the outlet end of such section, and means for directing at least one heating flame into the settling zone below such refractory means.

3. In a horizontal reverberatory type smelting furnace having a smelting section and an exhaust duct leading from the outlet of such section, a settling chamber below such duct and having its floor positioned below the level of the floor of the smelting section, a refractory wall extending rearwardly from the furnace front wall over the settling chamber and between such chamber and such duct, and means independent of the heating means for the smelting section for heating the settling chamber.

LEVI S. LONGENECKER.

(References on following page) 7 REFERENCES CITED Number The following references are of record in the 1,500,651 file of this patent: UNITED STATES PATENTS 5 2:180:08!) Number Name Date 645,179 Miles Mar. 13, 1900 732,265 Boss June 30, 1903 Number 732,268 Boss June so, 1903 726,466

Name Date Smith July 8, 1924 Frink Mar. 25, 1930 Morton Mar. 8, 1938 McDermott Nov. 14, 1939 FOREIGN PATENTS Country Date France Mar. 7, 1932

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