US1316267A - Metallurgical furnace - Google Patents

Description

Patented Sept. 16, 1919.

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METALLUBGICM. FURNACE.

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Patented Sept. 16, 1919.

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W. 0. BORCHERDT. METALLURGiCAL FURNACE. Armcmon man we zr. ma.

Patented Sept. 16, 1919.

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UNITED STATES PATENT OFFICE.

WALTER 0. BORCHEBDT, 0F AUSTIN'VILLE, VIRGINIA, ASSIGNOR T0 THE NEW JERSEY ZINC COMPANY, OF NEW YORK, N. Y., A CORPORATION OF NEW JERSEY.

METALLURGICAL FUBNACE.

Specification of Letters Patent.

Patented Sept. 16, 1919.

To @ZZ whom 'it may concern:

Be it known that I, WALTER 0. Boncunnn'r, a citizen of the United States, residin at Austinville, in the county of Wythe, State of Virginia, have invented certain new and useful Im rovements in Metallurgical Furnaces; an I do hereby declare the following to be a full, clear, and exact description of the invention, such as vvill enable others skilled in the art to which it appertains to make and use the same.

This invention relates to metallurgical furnaces, and has for its object the provision of certain improvements in such furnaces. More particularly, the invention relates to metallurgical furnaces for producing volatile metallic oxids, or sulfates, or basic sulfatos, such as zinc oxid, lead oxid lead sulfate, and the like, or mixtures of two or more of them. The aim of the invention in this connection is the provision of an improved furnace construction enabling the convenient firing, charging and Working of the furnace without contamination of the flue system with impurities. To this end, the invention contemplates the provision of an improved valve or damper, operatively included in the flue system of the furnace and adapted in one position to permit the' passage therethrough of volatile products, and in another position to prevent the 4assage therethrough of such products, While at the same time establishing communication between the combustion chamber of the furnace and the outside atmosphere, and in an intermediate position to permit of the entrance to the flue system of a regulated amount of air, when that is desirable.

The features of the invention Which are believed to be patentable are definitely set forth in the appended claims. These features, together With the construction and mode of operation of a furnace embodying the same, Will be best understood from the following description taken in conjunction With the accompanying drawings, in Which- Figure 1 is a transverse sectional elevation of a metallurgical furnace embodying the invention; Fig. 2 is a plan, artly in section, of the furnace, and Fig. 3 is a front elevation of the furnace.

The furnace `illustrated in the accompanying drawin fs is built of fire brick, or other suitable re ractory n'iaterial, suitably supported and strengthened by a steel framework of the usual type. The furnace illustrated in the drawings is composed of a series of sections or separate furnace units. Each furnace unit is operatively independent of the other units, although mechanically all of the units are combined in a single structure. The furnace units are arranged side by side, and each unit has an opening 5 at each end thereof. Vertically sliding doors 6 are arranged to completely close these openings or to regulate the opening thereof as desired. Each furnace unit has a grate 7 for supporting the charge, and through which air or other gaseous reagent may be blown or drawn.

The arch or roof 8 of each furnace unit has a pair of openings 9 therein, Which may be used for charging or which may communicate with a main Hue or conduit 10, as hereinafter more fully explained. The main flue 10 is in the form of a conduit or tunnel extending transversely of the furnace units and is common to all of these units. This flue is built of fire brick, or other suitable refractory material and is arranged above the furnace units and suitabl supported by the steel frame work thereofi A short vertical {iue 11, of refractory material, is arranged above each of the openings 9 and registers therewith. The openings 9 in the arch of the furnace are preferably lined with a fire brick arch 12. The vertical tiue 11 is supported by the steel framework of the furnace, and the space between the lower end thereof and the upper end of the arch 12 may be sealed with dust 13, or the like.

The main or transverse fiue 10 is provided With a short horizontal flue, of refractory material, 14, for each of the vertilcal flues 11. The corresponding and coperatin short ues 11 and 14 ths extend at rig t angles to each other, and these flues are so arranged that their central axes intercept. The fines 11 and 14 form, in conjunction With the valve or damper to be hereinafter described, an auxiliary flue from the combustion chamber of the furnace to the main or transverse fine 10.

The valve or damper connecting the short flues 11 and 14 consist of a hollow cylindrical drum 15 having a substantially semicircular port or opening 17 in its cylindrical side. Each cylindrical valve is rotatably mounted on four stationary rollers 1G and is arranged to be turned so that both lines 11 and 14 are in communication with the hollow interior of the val ve through the port 17 thereof, as indicated at the right in Fig. 1, or so that the flue 14. is closed and the flue 11 in communication with the outside atmosphere through the. port 17 of the valve, or so that the flue 14 is in communication with both the flue 11 and the outside atmosphere.

The outer peripheral end surface of the horizontal fine 14 and the u )per peripheral end surface of the vertical flue 11 are concave to provide a relativel snug' fit between these flues and the cylindrical surface of the drum. These concave peripheral end surfaces have substantially the saine center of curvature and may be considered as valve seatsy l'or the rotatably mounted hollow c): .liudrical valve 15. ll will be evident from the drawings that thc cylindrical valve l5 is inountcd for rotation about a horizontal axis substantially intcrcepting the intersection of the central axes of the fines l1 and 14 and substantially at right angles to each of these axes.

The hollow cylindrical valve 15 is of fire brick, or other suitable refractory material, and may be conveniently built up of three main parts or elements; (.1) a substantially semi-cylindrical shell a., and (2 and 3) circular end closures Zi and c, each of which has a substantially semi-cylindrical peripheral flange d of the saine external and internal diameters as the shell a, and adapted to coperate therewith to form the outer cylindrical surface of the drum with the port 17 therein. This construction of the cylindrical valve 15 will be clearly seen from an inspection of the lower left-hand corner of Fig. 2 of the drawin s. The end closures b and o are bolte to metallic end plates 18. Each end plate has an inwardly extending cylindrical ring or flange 19 to which is integrally secured a bracket 20. A back plate 21 is bolted between the brackets 20 and serves to securely hold the shell a and end closures b and c in position.

A sprocket wheel 22 is secured to the outer end of each plate 18, and is preferably integral therewith. A sprocket chain 23 engages with each of the sprockets 22 and with sprockets 24 secured to a rotatably mounted shaft 25. A worm wheel 26 is secured to each shaft 25 and meshes with a worm 2G on a shaft 27. The shaft 27 has a squared end with which a wrench or hand wheel may be associated for rotatin the shaft to turn the hollow cylindrical valve or damper 15. Since the valve is never called upon to make a complete rotation, the sprocket wheel 22 may advantageously take the form of'a smooth wheel-or circular flange and the sprocket chain 23 can be bolted thereto at one point.

The hollow cylindrical valve, 15 is so mounted that the cylindrical ianges l) of the end plates 18 act as tires and rest upon the rollers 1G. By rotating the shaft 27, the cylindrical valve cau he turned to any desired operating position. ln one extreme position, determined by the engagement of the hack plato 21 with the upper end of the vertical flue 11. or its steel reinforcin frame 11', the port 17 of the hollow cylindrical valve establishes communication between the flues 11 and 1l and thus permits the passage of volatile products from the combustion chamber of the furnace to the main flue 10, as illustrated at the right in Fig. 1. In its` other cxtreme position, determined by the engagement of the back plate 21 with the upper outer cud of the horizontal liuc Il, the valve serves to close the Hue 14- and at the saine tiiuc establishes. through the port 17, coininunication between the coinhustion chamber of the furnace and the outside atmosphere, as indicated at the left in Fig. 1 of the drawings. If desired, the valve may be turned to occupy any position intermediate the two extreme positions just described and illustrated in Fig. 1. In Fig. 2 of the drawings, the positions of the two valves of the upper furnace unit correspond to the positions of the valves in Fig. 1. In the lower furnace unit of Fig. 2, the left-hand valve 15 is turned to establish communication, through the port 17, bctween the flue l1 and the Hue 14. The right-hand valve 15 of the lower furnace unit has been omitted in Fig. 2 in order to show the upper construction of the vertical flue 11 and the arrangement of the rollers 16.

A hopper 30 is suspended from I-beam trolleys 31 and is thus adapted to be moved into chai-ging position with relation to any one of the furnace units. A pivoted chute 32 is mounted at the lower end of the hopper in order to facilitate delivery of the charge into the port 17 of the cylindrical valve, lVhen the hopper is to be moved along the trolleys 31, the chute 32 can be turned up out of the way.

The operation of the furnace will be better understood from the following description: When the charge of zinc ore and coa-l has been smelted in the combustion chainber of the furnace for a. sulicient length of time, so that the larofer part of the zinc and other valuable metals has been driven out, the valve or damper is rotated to the position whereby the main flue is cut off from the atmosphere and combustion chamber, and the combustion chamber is put into communication with the atmosphere. The doors 6 at the ends of the combustion chainiber of the furnace are then opened and the spent char rc or clinker is 'broken up by means of Aars and scrap-ed out into the clinker pit. A charge of fine coal, known as bed or firing coal, is then dumped upon the grate from an overhead hopper through the rotating valve, or else is thrown in through the open doors by means of shovels. This bed coal is then leveled by means of scrapers into a uniform layer 'and the doo-rs (i are either then closed or a piece of lightsheet-iron is hun over the opening to keep out excess air. he fire-brick arch of the furnace, still red hot from the previ-ous charge which has been smelted therein, radiates sufficient heat to the bed coal to cause its prompt ignition. As soon las this ignition has taken place, air is admitted under the grate, which. blowing up through the coal, fans it into incandescence, the dust and smoke, or soot, passing out to the atmosphere through the rotating damper. As soon as the excess of volatile matter has been burned out of the coal, and it has assumed a uniform clear glow and emits a clear flame, the air pressure under the grate is cut ofi" and the mixed charge, consisting of zinc. ore and coal, or coke, and any desired flux, is placed in the furnace by dumping it from the overhead hopper 30 through the rotating valve and into the combustion chamber. This charge is properly leveled off and the doors of the furnace are then closed; a pressure of air again being admitted under the gratas. In a short time the charge of ore and coal is ignited by the comb-ined action of the incandescent bed coal and the radiant heat from the fiie-brick arch of the combustion chamber. At first, this `action results in the sintering or sticking together of the ore articles, also sometime-s called fritting, an during this period considerable quantities of water vapor lare distilled out of the charge and expelled to the atmosphere through the rotating damper. The charge then commences to ignite and quantities of smoke, consisting of soot and dust, are expelled to the atmosphere, and as the temperature of the charge gradually increases, the more volatile metals, such as cadmium, commence to distill ofi'. After the combustion of the charge has progressed still further, zinc and lead begin to distil off, and with the apiearance of a sufficient volume of the white umes evidencia the presence of the oxids of these metals, t e rotating damper or valve is turned into that position in which the combustion chamber of the furnace is directly connected to the main flue, so that these metallic oxids are drawn, by the action of a fan, through 'this main flue and various connecting flues to the 1point of collection at the bag hiouse. If, during the working of the charge, it becomes desira ble to admit atmospheric air to the main flue, this may be "accomplished by turning the rotating valve to an intermediate position, so that air can be drawn into 'the main flue without interrupting the connection bctween the combustion chamber of the furnace and the main iue. When the charge has been worked the required time, the above cycle of operations is repeated.

The functions of the rotatable valve or damper in the flue system of the furnace are three-fold. ln the order of their relative importance, these functions may be tabu lated as follows:

(l) In one position, to permit the passage therethrough of volatile products and gases from the combustion chamber of the furnace to the main flue, and at the same time to cut ofi' the main flue from the atmosphere.

(2) ln another position,

(a) to permit carbon or soot and (or) reducing gases to be expelled to the atmosphere from la freshly ignited charge, thus making practicable the use of coal which would not otherwise be suitable because the carbon or soot would blacken the oxid or other valuable product of the furnace, and the carbon, or reducing gases, would interfere with the oxidization of zinc to zinc oxid, or with other reactions which should take place in the main flue.

(b) to permit of turning to the atmosphere volatile metals, such as cadmium, which are distilled out o-f the fresh charge before much zinc distils ofi', and whose presence in the product of the furnace is deleterious thereto, thus permitting the use of ore which would not otherwise be suitable.

(c) to permit of the excess water vapor from the fresh charge being expelled to the atmosphere.

(d) to permit top charging into the combustion chamber of the furnace, while at the same time preventing the entrance of air, gases, dust, or dirt into the main flue.

(3) In an intermediate position to permit of the entrance to the mam flue of a regulated amount of air, when that is desirable.

It will be seen from the foregoing description that the most important function of the rotatable valve is to provide for the elimination of excess carbon or soot from the bed coal, and from the coal mixed with the charge, and also to prevent the entry of dust to the main flue While the spent charge is being drawn and a new charge is being placed in the furnace. The provlsion of the valve thus enables the use of grades of coal which cannot be satisfactorily used in previously existing types of oxid furnace, because of the large amount of vollatile carbone contained in such coal. Semianthracite culm, containing about 14% of volatile carbon, may thus be satisfactorily used in my improved furnace, whereas this fuel causes so much soot as to make it impossible to produce clean oxid with any previously existing type of oxid furnace known to me.

l`rom the foregoing description, it will be observed that the entire Hue system of the various furnace units is composed of refractory material and is thus enabled to withstand the effects of very high temperatures. The volatile products from the combustion chamber thus come in contact with no metallic parts during their passage through the Hue system. The hollow cylindrical valve 15, in so far as it constitutes a part of the Hue system, is likewise built of refractory material, and is thus enabled to withstand rthe same high temperatures as the other parts of the Hue system. The cylindrical valve rests on the four rollers 1G and is not otherwise mechanically secured or attached to the furnace structure. The valve can thus bc very conveniently removed for repairs by lifting it o-H` of its supporting rollers. The mechanical construction of the valve and its cooperating parts are compact and simple. and its operativi` mounting does not complicate the furnace structure. At the same time the use of this valve provides a convenient means for firing, charging and working the furnace and for preventing the contamination of the Hue system with dust and other impurities resulting from such operations.

I claim:

I. A metallurgical furnace comprising a combustion chamber having an opening in its roof. a Hue, and a valve operatively associa-ted with said Hue and arranged in one position to place said flue in communication with said chamber through said opening and in another position to close said Hue and to place said chamber in communication with the outside atmosphere so as to permit charging of said chamber through said phcre; substantially as described.

2. A metallurgical furnace comp-rising a combustion chamber, a Hue communicating with said chamber, a cylindical valve operatively included in said flue, said valve having a port in its cylindrical side, and means for turning said valve so that in one position thereof said port permits the passage thro-u h the Hue of volatile products from said c amber and in another position thereof said ort establishes communication between said chamber and the outside atmosphere; substantially as described.

3. A metallurgical furnace comprising a combustion chamber, a main Hue having an inlet Hue communicating therewith, an auxiliary Hue communicating with said chamber, said inlet Hue and said auxilia Hue each having a concave valve seat with substantiall the' same center of curvature, a hollow cy indrical valve operatively associated with said valve seats, said valve having a port in its cylindrical side, and means for turning said valve so that in one position thereof said port establishes communication between said auxiliary Hue and said inlet flue and in another position thereof said port establishes communication between said auxiliary flue and the outside atmosphere; substantially as described.

4. A metallurgical furnace comprising a combustion chamber, a plurality of auxiliary Hues communicating with said chamber through the roof thereof, a main flue havinrr an inlet Hue for each of said auxiliary ues, a valve cooperating with each auxiliary flue and its corresponding inlet Hue, and means for turning each of said valves so that in one posit1on thereof the auxiliary Hue is in direct communication with the main Hue and in another position thereof the corresponding inlet flue closed and the auxiliary Hue is in communication with the outside atmosphere; substantially as described.

5. A metallurgical furnace comprising a pluralityv of combustion chambers arranged slde by side, a main Hue arranged above said chambers and extendin transversely there of, an auxiliary Hue or each combustion chamber operatively connecting the chamber to the main Hue, and a valve operatively included in each of said auxiliary Hues and arranged in one position to open the Hue to permit the passage of volatile products' therethrough and in another position to close the Hue to the passage of such products and at the same time to establish communication between the chamber and the outside atmosphere; substantially as described.

6. A metallurgical furnace comprising a combustion chamber, a flue communicating with said chamber and having two sections arranged substantially7 at right angles to each other, a cylindrical valve operatively connecting said two Hue sections, said valve having a port in its cylindrical side, and means for turning said valve so that in one position thereof ,said Hue sections are in communication through said port and in another osition thereof, one of said Hue sections 1s closed and the other flue section is in communication with said chamber and with the outside atmosphere through said port; substantially as described.

7. A metallurglcal furnace comprising a combustion chamber, a main Hue, an auxiliary flue operatively connecting said cham-` ber with said main Hue, a hollow cylindrical valve operatively included in said auxiliary Hue, said valve being composed of a sector-shaped cylindrical shell and circular end closures having sector-shaped Hanges secured together to form a hollow cylinder with an opening in the cylindrical side thereof, and means for turning said valve whereby both said main and auxiliary Hues,

or only said auxiliary flue, may communicate through said opening with the hollow interior of the valve; substantially as described.

8. A metallurgical furnace comprising a combustion chamber, a flue of refractory material communicating with said chamber and havin two sections arranged substantially at right angles to each other, a cylindrical valve of refractory material operatively connecting said two flue sections, said valve having a port in its cylindrical side, and means for turning said valve whereby said port is in communication with both or only one of said two flue sections; substantially as described.

9. A metallurgical furnace comprising a combustion chamber, a flue communicating with said chamber, a hollow cylindrical valve operatively included in said iue, said valve being built of fire brick and composed of a sector-shaped cylindrical shell and circular end closures having sector-shaped flanges secured together to form a hollow c linder with an opening in the cylindrical slde thereof, and means for turning said valve to bring said opening into the desired position; substantially as described.

10. A metallurgical furnace comprising a combustion chamber, a fluevof refractory material communicating with said chamber, and a valve of refractory material operatively included in said flue and arranged in one position to open said flue to permit the passage therethrough of volatile products Copies of this patent may be obtained for from said chamber and in another position to close said flue tothe passage of such products and at the same time to establish communication between said chamber and the outside atmosphere; substantially as described.

11. A metallurgical furnace comprising a combustion chamber, a flue of refractory material communicating with said chamber, a rotatably mounted hollow cylindrical valve of refractory material operatively included in said flue, said valve having a port in its cylindrical side communicating with the hollow interior thereof, and means for turning said valve to bring said port into the desired position; substantially as described.

12. A metallurgical furnace comprising a combustion chamber, a flue of refractory material communicating with said chamber, a plurality of stationary rollers, a hollow cylindrical valve of refractory material rotatably mounted on said rollers and operatively included in said flue, said valve being composed of a sector-shaped cylindrical shell and circular end closures having sector-shaped flanges secured together to form a hollow cylinder with an opening in the cylindrical side thereof communicating with the hollow interior, and means for turning said valve on said rollers to bring said opening into the desired position; substantially as described.

1n testimony whereof I allix my signature.

WALTER 0. BORCHERDT.

ve cents each, by addressing the Commissioner of lPatents,

Washington, D. 0.

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