US1339428A - Method of operating an electric furnace - Google Patents

Description

M. R. THEMBOURE METHOD OF OPERATING AN ELECTRIC FURNACE.

APFLICATI'ON FILED MAR. 24, I916.

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Patented May 11, 19200 EEAX. it. TREMBOUR, QIF WATEEVLIET, NEII' YORK, ASSIGNGB, BY MESNE ASSIG'EQ' MEETS, TQLUDLUM ELECTRIC FURNACE CORPORATIGE.

MEIHQB OF GPEEATING AN ELECTRIC FURNACE.

Be it known that 1, MAX R. Tnmucouu, a sub ect of'the German Emperor, residing at the city of Watervliet, in the county of Albany and State of New York, have invented certain new and useful Improvements in Methods of Operating anElectric 'l urnace, of which the following is a specification. My invention is a new method of melting and refining metals and alloys by means of electricalheating, and is especially adapted for use in"the electric furnace described in my copending application on electric furnaces.

lt has heretofore been believed by metallurgists that contact of a carbonaceous electrode with a molten charge of metal, such as iron or steel, would result in an excessive absorption of carbon by the metal from the electrode. For this reason great care has been exercised and various processed have been developed to maintain such electrodes out of contact with the metal-charge. hen in some types of furnaces electrical contact has been made to the molten metal an artificially cooled metal-electrode has been resortedto, or the use of electrically conducting refractory furnace-linings has been recommended.

I have found, however, that under certain conditions this absorption of carbon by the metal is so slow, particularly when agraphitic electrode is used,that during ordinary furnace operation the amount absorbed is quite negligible and is in fact less than required in any event for the great majority of electric-furnace products. These conditions can be obtained by means of an adjustable electrode introduced into the furnace from above the level ofthe charge and in adjusting this electrode, when the current is flowing, in such a way that it contacts with the metal so as to convey the current without appreciable heating effect at the contact points and withdrawing this electrode from contact with the metal when no current is flowing, unless it is intended to carbonize the metal by means of the electrode-carbon.

In accordance with my present invention, 1 have taken advantage of this discovery to provide an improved process of refining molten metals, whereby electrical heat is applied to the metal and tothe refining slag by means of adjustable carbonaceous elec- Specification of Letters Patent.

Patented May llfl, 192d. ieic. Serial no. 86,419.

trodes, at least one of which contacts with the metal without appreciable-heating effect, while at least one electrode is spaced away from the metal without contacting and at such. a distance as to produce the proper heating effect, forcing the current tb pass through the refining slag, which, according to chemical composition and physical properties, will offer more or less electrical re sistance. 1

l have also provided an improved process for the melting and refining of a metal charge, wherebythe same electrical equipment is used for both phases of the process, in such a way that during the melting pe riod, when the furnac and its contents arc still relatively cold, all t e electrodes are adjusted in such a way as to gencrate heat. while during the reli ing process at least one electrode is adjusted to Contact with the metal, thus eliminating the heating effect of the same. and transferring it to the other electrode or electrodes, which are kept.v spaced away from he metal without contacting. The electric current employed in 8 this process must be of a tension sufficient to bridge aingaps poor contacts by an arc and to force its way through semi-conductive materialsuch as slag, for which purpose a voltage of around. 100 volts between the phases has been found very satisfactory for a basic furnace, while an acid furnace re quires a still highe voltage.

In the preferred embodiment of my invention the process is carried out in an oblong furnace chamber with a clmrgiug door, 3. at each end of the longer axis {an electrode, i and 6, near each door where the dissipation of heat is greatest; and an electrode, 5, near the center of the furnace. This furnace is described in the copending application and shown in the acconuaanying drawing, in which: I

. Figure 1 is a plan.

along the lines, aa, on

n i a g. 2 is a section E19". 1.

51g. 3 is a section along the lines, b b, on Fig. 1.

Fig. a is a side elevation.

we is Similar letters refer to similar parts throughout .the several views.

Cold metal scrap may be heated and melted in this furnace in any convenient Way, for instance, by striking an arc to the metal from each electrode, thus distributing the heat throughout the chamber, which is desirable when the furnace is cold one the doors kept closed.

d lien a fluid metal bath, 7, has been oband the has been covered with the refining slag, 8, the middle electrode, is lowered tarough the slag to contact i a metal. T his at once increases the seating enect at the lower ends of the outside electrodes, and 6, at the same time veringthe temperature in the center of a furnace. In other words, the heat is cneinted and apo ied to the metal and slag near the doors, wnere at the time oi refining it is mostly needed, due to the fact that the doors must be opened repeatedly for observing and. man.ij ulating the slag, for San g and for making additions. Applye heat where it is needed, not only c power, but also prevents ov rp lin i a or d on it M w i and around clriy l I but it may rormed, and ith the metal process is still carried- 01L is adaptable to any ccnnnei yphaqe alternating current off trz'insforinerconnection may be used and the contacting electrode may be cc nected directly to one or the lines or phases, or in such a way as to form the neutral pointsystem.

of tne licre'special current conditio..-s favor the "'or t' n of electrodecarbon by the metal, a; rig electrode should be a usted in such r that the same touches the ctal, col tacting only sulllciently-to convey current without appreciable heating cl? ccntactpoints, it is also 1,: use a ph carboi being a- HiiiCli be r conductor carbon,v rc uires a much con -.ct surface for a given curr ll minimize the carburizan r: C";

desire ing and refining .n electric fumacc which consists ing an electric current through the c between an electrode adjusted to are ,he charge and an electrode of carbonainaterial adjusted to contact with the using the electric current" both to r a bath, while :1 rest 0'." in process cit melting. it

lessees supply heat at the arcing electrode as well as to prevent carbonization of the char e and dissolution the contacting electr e.

2, The method of melting and refining metals in an electric furnace which consists in passing an electric current through the charge between two or more electrodes, one at least of which electrodes is in arcing relation to the charge, and another of which electrodes is', or a plurality of other which electrodes of the same polarity are, of carbonaceous material, and directly contacted process by keeping'the electrode ends on,

of perfect contact with the metal charge, and in substantially eliminatin this heating of one or more electrodes during the refin ing process by directly contactin the ends of these electrodes with the me ted metal charge, thus transferring the heating effect to the other electrode or electrodes.

4-. "The method of electrically refining and melting metal which consists in adjusting the electrodes near the door-opcnin s of the furnace so as to be discontactcd from the charge and. to supply heat, while adjusting one or more 01:": the electrodes remote from the doors so as to contact directly with the charge, thus conveying the current without appreciable heating effect. I

5. The method of operatin an electric furnace for the melting and re 'ning' of metals, which consists in supplying the heat required for the melt-ing'uniforml from all electrodes, and then refining t e molten metal in contact with a suitable slag and eliminating the heating effect of any or all of the electrodes remote from the door-openings and concentrating it upon the electrodes near the doors.

6. The method of regulating heat in an' e ectric furnace -for the melting and refining of metal, which consists in conveying the electric current to acharge by a number of carbonaceous electrodes and in substantially eliminating the heat under one or more of the electrodes by contacting the same with the charge'only during the How of current,

thereby continuing to carry current thro'u h this electrode while transferring the heating one electrode directly'with said pool ofmol- ,ten metal so as to convey the current by this electrode without an arc, while maintaining the arcs on the other electrode or electrodes.

8; The method of melting and refining metal in an electric furnace of elongated shape, having a series of electrodes extending lengthwise of the furnace, which consists in adjusting the outer electrodes to be out of contact with the charge, and to supply heat, while adjusting one or more of the intermediate electrodes to contact with the charge, thus conveying the current with 15 less heating effect in their region.

In testimony whereof I have afiixed my signature in presence of two witnesses.

MAX R. TREMBOUR. Witnesses:

J. WM. CRU'MP, v CLARENCE B. BOYNE.

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