US1216961A - Electric furnace. - Google Patents

Description

H. DE NOLLY. ELECTRSC FURNACE. APPLlcATioN-HLED 11111. a1. 1914.

A Patented Feb. 20, 1917.'

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HECTOR DE NoLLY, 0F sT. cHAMoND, FRANCE, AssIoNoR 'ro SOCIT ELECTB0- MTALLURGIQUE DE sT. BRON, oF LYON, FRANCE.

ELECTRIC FURNACE.

. p Specification of Letters Patent.

Patented Feb. 20, 1917.

Application filed January 31, 1%.)14. Serial No. 815,802.

To all whom z't may concern.'

Be it known that I, HECTOR DE NOLLY, a citizen of the French Republic, residing at St. Chamond, in the Republic of France, have invented certain new and useful Improvements in Electric Furnaces, of which the following is a specification.

The present invention has for its object an electric furnace suitable for all purposes in the electro-chemical industry, but which, owing to its special arrangements, is more particularly applicable to the fusion of ferro-alloys such as ferromanganese, ferrochromium, ferrosiliciuni and so forth utilized in the manufacture of Steel.

The furnaces intended to fuse the alloys which serve as addition.' in the manufacture of steel or of any other metallurgical compound, should permit of the frequent taking of a variable quantity of fused metal; particularly in the case of products obtained in the converter. Hitherto only rocking furnaces have rendered it possible to solve this 'problem in a satisfactory manner, but in addition to the complicated mechanism that they necessitate, these furnaces present the disadvantage of allowing the scoria to be poured at the sametime as the metal which constitutes a double inconvenience.

1. As this scoria is added to that already contained in the converter or the pocket there is a risk of its remaining mixed with the steel and moreover it frequently exerts a corroding action upon the linings of the furnace.

2. As this scoria is partially eliminated each time a quantity of metal is taken it must be re-formedv to the detriment of the alloy, while if itis caused to remain constantly in the electric furnace, the loss of metal and the wear of the lining are simultaneously reduced, because when once it has become saturatedwith the oxid of the produce that is being fused, it reaches a neutral condition and ceases to exert any harmful effect either upon the bath or the lining.

An example of the improved furnace is illustrated in the annexed drawings.

` Figure Al is a vertical section of the furnace. l

Fig. 2 is a plan view of Fig. 1.

The furnace comprises essentially a fusion chamber of large horizontal section in which two electrodes A of like polarity operate. These electrodes may, however, by means of a suitable switch c2 he given different polarities at certain tines, for instance, to prime the furnace or for any other exceptional eircumstances but in normal working thev have the same polarity. The switch a2 directly connecting the conductor c fixed to one of the electrodes A with theA positive pole of source S of electricity and the other electrode A is in constant connection with the same b V means of the conductor a.; and by turning the switch at the conductor a can he connected with the negative pole of S. The electrodes A are arranged' above a hearth B containing the metal of the same horizontal section as the fusion chamber and placed in communication with a fore-hearth C which is preferably lined with electric conducting material and which the fused metal is only able to enter through a passage l) which forms a siphon and through which it is impossible for the slag indicated at b to pass. The fore-hearth is provided with upright electrodes E of which the lower ends are in electric contact with the conductive lining J. .l of the fore-hearth C; the upper ends of the electrodes E are connected by means of the conductors c c with the negative terminal of the source S of electricity which is therefore of contrary polarity to that for the electrodes A during normal working of the furnace. Moreover the section of the fore-hearth C and the section of the passages D which connect the bottoms of the hearth and fore-hearth, are together less than the horizontal section of the hearth B. so that, owing to the increase in density of the electric current produced by this reduction of the respective sections of C and I), the fused metal therein, free of scoria, is

sup \.rheat(al and maintained in a condition of perfect fluidity. AIf ata given moment the temperature of the metal contained in the fore-hearth is found to be too high, it is sufficient to change for a short time the polarity of one of the principal electrodes A by means of the switch a2 so that the conducting wire c connects the said electrode with the negative terminal of the sourci` S of electricity and that only part of the, total current passes through the fore-hearth and which will almost immediately result in the desired lowering of temperature: when by again turning the switch a2 normal working can be resumed. The two main electrodes A are guided and caused to effect a movement-of ascent and descent by means of a screw rod F operated by means of a crank G and gear wheels G', G2, the said rod turning in a fra-me F', supporting the elec! Aelect-rie furnace remains very low, at all events in certain cases, in such a manner as vto avoidvolatilization, should presenta very large cross section and cover the metallic bath almost completely f'h'ich has the great advantage of avoiding so called vaults which in ordinary furnaces are rapidly rendered useless and constitute an important source of expenditure, apart fromitlie difficulties and stoppages necessitated by their replacement.

By causing one of these electrodes A to descend into the metallic bath, the.e fused alloy is forced into the fore-hearth and'is poured by means of a spout H, lthe sill vof which is above the normal level of the fused metal in the hearth, the said `.spout leading into a pocket not shown in the drawings arranged on abalanced bridge the oscillation of which, lwhen it has received the desired weight of metal, establishes an electriccontact which automatically causes the electrode to rise. In view of the large cross section of the electrodes A, a very small movement of the same is sufficient for displacing the necessary quantity of metal.` If desired, a yedunterweight arranged upon the beam `carrying the pocket: might be displaced in such a ,manner that the Vllatter does not descend until the moment when it lilas lreceived the necessary weight of metal, which may vary from one operation to another. y r

During the downward movement of one electrode A, the other electrode can be 'raised in'such a manner asl to free the aperture through which it enters the furnace, and the quantity of solid ferro-alloy intended 4to replacethe (luaiitity removed in the liquid state can he in reduced ln cases in which a refined alloy is to be fused the carbon lining J, J, of the foreliearth can lie replaced either by a lining J1,- J. of iion-carboiiizing conducting materials electrically connected with the negative pole of thc source by means of the conducting wire c1, or hy any other suitable lining of non-conducting materials, thereturnof the current being insured (Figs. il and 4) either v in the ytiret case,jhy condiuitor e, or, in the latter case', 'h v. means cfa' pendent electrode ll" connected with the negative pole S 4by conductor c2, switch c and conductor cl. ln cvci'y case the` lining J is connected with the negative pole of H by conductor c. 'Ilie pendent electrode F1 can be left almost conithese electrodes pletely short-circuited into the fore-hearth C upon the fused metal Without the interposition of slag.

This electrode El ,can be raised or loW- ered and can be turned out, if desired, by means of a screw rod F3 operated by means of a crank G3 and gear wheels G4, G5, the said rod turning in a frame F4 supporting the pendent electrode E1 and slidingV on' guides F5, in such a manner as to allow its bringing out of circuit when a` suiicient temperatuie has been reached in the fore-hearth lining J1, J1, J1, directly connected if the with the negative pole of the source S of electricity, is formed of materials lwhich become conductois when heated.

The two main electrodes A being in parallel, there is never any difficulty in replacing one of them Without stopping the furnace; to do so it is only necessary to rotate through 90o the bracket from which they are suspended and to reduce momentarily the quantity of energy supplied to the furnace in such a manner that the density of the cur# rent passing through the electrode which alone remains operative, does not exceed the maximum permissible in practice.

Similarly in case in which the two main I electrodes A are of different polarity one of them can be dispensed with for its replacement because the proper circulation of current can always be insured by giving previously the positive polarity to the other electrode A which remains in circuit, the return being insured by the lining J or J1L or by the pendent electrode E and lining J (Figs. 3 and 4) of a larger or smaller fraction of the total current. y

The lining .of the furnace is constituted by'. appropriate materials either basic, acid or neutral according to the naturemf the ferro-alloys to be fused.

The slag contained in the .furnace being always the same there is no inconvenience in its presenting any desired thickness and this consideration, in conjunction'with the eniployinent of a low voltage, explains the possibility of avoiding volatilization almost completely even iii the case/of highly volatile metals such as manganese zinc and so forth,-

because the arc propercan always be disestablished and the furnace operated in series.

Finally, a tapping hole I- is provided which permits of emptying the furnace completely when it is desired to stop or repair: it.

lV hat l claim as my invention and desire to secure by Letters Patent of the United States is I; i

l. iln'an electric furnace for the fusion of metals, the combination ofa hearth of large section forming the lower part of a fusion chamber, a fore-health of `smaller .section than that of said hearth, conduits connecting, below the surface of the fused metal.

'ica

l to stop its working,

the bottom of said hearth with the bottom of said fore-hearth, so that the scoria which forms in the hearth cannot pass into the fore-hearth which is electrically connected with the negative pole of the source of electricity, an outlet conduit from said forehearth the sill of which is above the normal level of the surface of the fused metal in the furnace and allowing the metal of the fore-hearth to flow out when the level of the said metal is higher than the sill of the said outlet conduit, means allowing the furnace to be completely emptied when it is desired two vertically movable electrodes in said fusion chamber covering almost entirely the surface of the metal contained in said hearth, a switch for connecting; one of said electrodes to either or other of the poles of the source of electricity, the other electrode beinf,r connected with the positive pole of the said source of electricity and means whereby either one or other of the electrodes may be forced down into or removed from the metal contained in said hearth.

2. In an electric furnace for the fusion of metals, the combination of a hearth of large section forming the lower part of Va fusion chamber, a fore-hearth of smaller section` than that of said hearth, conduits con necting, below the surface of the fused metal,

'the bottom of said hearth with the bottom of said fore-hearth, so that the scoria which forms in theA hearth cannot pass into the fore-hearth which is electrically connected with the negative pole of the source of electricity, an outlet conduit from said fore-A hearth the sill of which is above the normal level of the surface of the fused metal in the furnace and allowing the n'ietal of the fore-hearth to How out when the level of the said metal is higher than the sill of the said outlet conduit, means allowing the furnace to bc completely emptied when it is desired to stop its working, two vertically movable electrodes in said fusion chamber covering almost entirely the surface of' the metal contained in said hearth, a switch for connecting one of said electrodes to ciiher one or other of. the poles of the source of cleitricity, the other electrode being wie ncctcd with the positive pole of the said source of electricity. 'means whereby either one or other of the electrodes may be forced or a f necting, below the surface of the iused metal,

2h the bottom that the scoria which the bottom of .said hearth w of said fore-hearth, so

forms in the hearth cannot pass into the fore-hearth which is electrically connected with the negative pole of the source of electricity, an outlet conduit from said forehearth the sill of which is above the normal level of t-he surface kof the fused metal in the furnace and allowing the metal of the forehearth to flow out when the level of the said metal is higher than the sill of the said outlet conduit, means allowing the furnace to be completely emptied when it is desired to stop its working, two vertically movable electrodes in said fusion chamber coveringrr almost entirely the surface of the metal con-- tained inv said hearth, a switch for connecting one of said electrodes to either one or other of the poles of the source of electricity, the other electrode being connected with the positive pole of the said source of electricity,

means whereby either one or other of the electrodes may be forced down into or moved from the metal contained in said hearth, a liningv of fire-proof material and conductive of electricity arrai'ig'ed Vin said fore-hearth and a vertically displaceable pendant electrode forming the electric connection of said fore-hearth with the negative pole of the source of electricity, the lower end of said pendant electrode being,r brought almost into contact with the surface of the fused metal contained in said fore-hearth.

In witness whereof I have sig-ned this specification in the presence of two witnesses.

HECTOR nu NOLLY. [Ls] lVit-nesses:

ALMN 'DU Palin, JNAN (nnimwn.

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