US1191435A - Process for the electric melting of metals. - Google Patents

Description

c. A. KELLER-.-

PROCESS FOR THE ELECTRIC MELT ING 0F METALS.

APPLICATION ElLED 056.23, 1913.

Patent'ed July 18, 1916.

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same cnARLEs ALBERT KELLER, or PARIS, ERANcE.

Specification of Letters Patent.

PRocEss FOR THE ELEcTRIc MELTrNG or METALs.

Patented July 18, 1916.

flriginal application filed August 12, 1902, Serial No. 119,385. Divided and this application filed December 23, 1913. Serial No. 808,333.

To all whom it may concern;

I Be it known that I, CHARLES ALBERT KEL- LER, a citizen of the Republic of France, residing at Paris, France, have invented certain new and useful Improvements in Processes for the Electric Melting of Metals, of" -which the following is a specification.

The obj ect'of the present application is an electric process for melting and refining metals and other substances, particularly iron, cast iron and steel, applicable to various metallurgical operations, for instance, (1) the introduction into one receptacle of one or several tappings coming from one or several melting apparatus, and there maintaining them at a temperature produced by electric current; (2) the refining of the ma terial or its mixture with others at anymoment; (3) the melting, and the mixture of metallic waste, particularly of iron and steel.

. The process is based on the employment of an auxiliary chamber, generally a casting ladle, the contents of which can be easily and'rapidly interposed in an electric circuit or be subjected to the action of the latter.

The annexeddrawing gives an example of apparatus suitable for carrying out the process, in which the figure shows the arrangement when a casting ladle is used. In said figure, the casting ladle a rests, by means of pivots or trunnions, on one end of a beam 6,

the other end of which carries a counterweight 0 intended for balancing the ladle and its charge; this beam is carried by a truck d, which can be moved on rails. This arrangement allows of bringing the ladle a to the proximity of a melting furnace to receive the successive tappings, or to the proximity of each of a series of furnaces to receive in succession the tappings from such furnaces; it also permits of bringing the dle under an apparatus comprising vertical electrodes e, 6 supported by chain tackle so as to raise or lower them into the ladle for the requirements of the operation as hereinafter described.

The ladle at, having a refractory lining, does not form part of the electric circuit; the current enters and leaves through vertical electrodes 6, 6, arranged above it; these electrodes can be regulated and each constitutes in eflect a separate furnace, and in practice I employ more than two electrodes for each pole; this permits of always being able to reace an electrode at Work without inter rupting or disturbing the .course of the oper ation. If only one electrode were provided, its removal would cause the breakage of the circuit. On the other hand, if each pole carries a minimum of two'electrodes, it will be possible to remove one of them and this would only result in an increase of current in the remaining electrodes.

As an example the manufacture of iron or of steel will be described. The metal, iron or steel contained in the ladle can be easily put into the electric circuit through the suitable lowering of the electrodes into the bath. The ladle is carried on a truck adapted to be moved so as to be brought successively under the tapping orifices of furnaces of the same battery. This arrangement will be particularly useful with a battery of electric furnaces, as the respective output of this kind of apparatus is less than that of blastfurnaces or metallurgical melting furnaces of the ordinary kind. After each tapping or set of tappings the molten material finished and otherwise ready for casting contained in the ladle is introduced into the electric circuit and the reheating is effected by a current of suitable strength, regulatable as required. By these means the metal is maintained at the required temperature; the

quantity of heat necessary for this purpose will simply compensate that quantity lost by radiation.

I The slag which will -l1ave probably been tapped with'the metal from the furnaces is removed in convenient quantity from the ladle so as not to be superfluously reheated.

vThis removal is eflected bysimply tilting the ladle.

The electric current is' interrupted when l the ladle has again to'be placed under the openings of the melting furnace or furnaces, to receive. a further tapping or tappings and-the reheating, if-required thentakes place as described above.

By this process a new method of working 1s reallzed; very large castings of iron or steel can be made with apparatus, the practical output of which is much less than the weight of these pieces. The temperature of the molten metal can be easily regulated and the metal remaining in the ladle after tapplng Wlll not be wasted as often happens,

as it can be kept hot until mixed with other tappings; the founder can therefore estimat t e amount of metal req i d forth filling up of large molds without fear of waste resulting from too high an estimate, which leads him sometimes to under-estimate and to spoil castingsthrough insufficiency of metal in the ladle.

To refine or make additions .to the metal collected in the ladle itis introduced into the electric circuit, and the removal of slag proceeded with if required, as already described; the current is then regulated so as to considerably reheat the metal to berefined, and the necessary additions are then made to obtain the required quality. For example, steel can be manufactured with cast iron from ordinary cupolas by refining this castiron by the addition of oxid and, just as in the Martin furnace, one can desulfurize, dephosphorize and deoxidize.

This process therefore permits of transforming an ordinary 3 foundry into a steel foundry. This process of refining or mixing can also be employed for the metal coming from ordinary furnaces as well as for that from electric furnaces. The process can also be easily applied to the melting and mixture of steel and iron waste which it may be required to remelt, owing to the extreme facility it olfers of taking samples, because of the continuous access it permits to the metal in the ladle. For this purpose a certain quantity of molten metalv (iron, steel or cast iron) is first introduced into the ladle, and a certain quantity of orewhich covers over the metal. The electric current is then passed intothe ladle and the operation having thus commenced, pieces of metal to be remelted and mixed are introduced into the liquid layer. These pieces of metal could not be placed in circuit in the empty ladle on account of their weak'elecmenses trical resistance, or an electric current of a strength inadmissible in practice would have to be used and which would cause large fluctuations in the operation. With this process, which utilizes the usual strengths of current employed in electric melting, the operation is rendered normal and effective by throwing the respective pieces of metal to be melted into the initial metal bath formed in the ladle as described. Under I these conditions, the electric working of the apparatus is in no way disturbed and when the melting is complete, the additions can be made and the operation efi'ected according to the usual method of mixing and refining of metals. It is evident that for the refining operations in the case of ladles, neutral, acid or basic linings are employed, as the case may be.

This application is a division of my copending application Serial No. 119,385, filed August 12, 1902.

I claim 1. The treatment of molten steel consisting in transferring it into an electric fur- In testimony whereof I afii x my signature in presence of two witnesses.

CHARLES ALBERT KELLER. Witnesses:

Hanson 0. (30x12, EDMOND JAC UAT.

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