US948343A - Electric furnace and method of operating the same. - Google Patents

Description

A. L. J. QUENEAU. ELECTRIC FURNACE AND METHOD OF OPERATING THE SAME. APPLICATION FILED NOV. 29, 1909.

948,343. Patented Feb. 8, 1910.

4 SHEETS-SHEET 1.

WITNESSES:

A.L.J.QUENEAU. ELECTRIC FURNACE AND METHOD OF OPERATING THE SAME.

' APPLICATION FILED NOV. 29, 1909, v 948,343.

Patented Feb. 8, 1910.

4 SHEETS-SHEET 2.

ATTORNEYS.

A. L. J. QUENEAU. ELECTRIC FURNACE AND METHOD OF OPERATING THE SAME.

APPLICATION FILED Rom-2e, 100a. 1 I

Patented Feb. 8,1910.

' INVENTOi? i W].

4 SHEETS-SHEET 3;

' ATTORNEY i f f 1 A. L. J. QUENEAU. I ELECTRIC FURNACE AND METHOD OF OPERATING THE SAME.

A'PPLIOATION FILED nov. 29, 1909.

948,343. Patented Feb.8 1910.

4 SHEETS-SHEET 4.

WITNESSES: INVENTOR I @Q/m M ATTORN EY6.

AUGUSTIN LEON JEAN QUENEAU, OF PHILADELPHIA, PENNSYLVANIA.

ELECTRIC FURNACE AND METHOD OF OPERATING THE SAME.

Application filed November 29, 1909.

Specification of Letters Patent.

Patented Feb. 8,119 10.

Serial No. 530,396.

To all whom it may concern:

Be it known that I, AUGUSTIN LEON J EAN QUnNnAU, a citizen of the Republic of France, residing at Overbrook, in the city and county ofPhiladelphia, State of Pennsylvania, have inventedcertain new and useful Improvements in Electric Furnaces and Methods of Operatin the Same; and I do hereby declare the ollowing to be a full, clear, and exact description of the invention, such as will enable others skilled in the art to which it appertains to make and use the same.

In the operation of electric furnaces, particularly those designed for the working and refining of iron and steel, serious difficulties have, in some instances, been noted, due to the so-called pinch eflz'ect, these difliculties sometimes resulting in the complete interruption of the operation of the. furnace. This pinch phenomenon, heretofore regarded as disastrous, and altogether to be avoided, I turn to useful account in the practice of my present invention, em loying it as an auxiliary to the electric urnace operation and, particularly, making it available as a means for more thoroughl mixin and refinin the charge. Thus, have iscovered that treated with a molten metal connection subject to the hydrostatic pressure of the bath, and by appropriately proportioning the electric current passing through saidconnection to the cross section thereof and to the hydrostatic head, I am enabled to roduce in the metallic connection and in c ose proximity to the bath a series of impulses or pulsations within the molten metal, which impulses or pulsationsare due to a series of disruptions of the molten metal in the connection and an alternate series of reestablishments of said connection. These disruptions are exhibitions of the action of the pinch phenomenon and the reestablishment of the connection after each disruption is, in my invention,

produced by the hydrostatic head of thesuperjacent metal in the bath; and the arrangement is such that at theplaoe where the resulting pulsations originate and where the disruptions occur, reducing conditions prevail so as to prevent the oxidation of the disrupted surfaces and. the interruption of the working current thereat.

In the accompanying drawin s, I have illustrated my inventionns app ied to an electric steel furnace, for which it is well providing the bath of metal to be adapted, but it will be readily understood that the heating and. mixing effect may be obtained in an electric furnace for the treatment of other metals (and also glass), or Wherever a molten metal, slag, salt or'other molten resister is to be used as the seat of the heating and mixing efiects, and whether the molten resister so employed is itself to be refined or varied, or whether it is employed for the purpose of transmitting its heating effects to a charge of some other material superposed upon it, as, for instance, a zinc ore charge made up of the usual mixture of zinc ore and coke for the production of spelter.

In the drawings, Figure 1 represents the adaptation of my invention to a tiltable steel furnace, the molten metal connections being adapted for use with a three-phase alternating current; Fig. 2 represents, on a smaller scale, a front elevation thereof, partly in section; Fig. 3 represents a horizontal section and plan view taken on a plane indicated by the line 3-3 of Fig. 1; Fig. 4 represents a view similar to Fig. 1, but shows a furnaceparticularly adapted for either a monoohasealternating current or a direct current; Fig. 5 represents a hori-' zontal section and plan view taken on a plane indicated by the line 55 of Fig. 4; Fig. 6 represents a section taken on a plane indicated bv-the line (3-6 of Fig. 4; and Fig. 7 indicates a further modification wherein the current, either direct or alternating, is used not only to produce the pinch effect in the molten metal connections from the bath, but also to develop the heating effect of an are produced between a top electrode and the bath orv the slag floating upon the bath.

Similar letters of reference indicate similar parts throughout the several views.

Referring to the drawings, it will be noted that I have chosen as an illustration a steel furnace of the tiltable type. Thus, in Figs. 1 and *2, the main body portion A of the furnace is mounted to rock upon the supports a and is provided'with the usual pouring nose b and with a hearth for containing the bath 0 of molten metal, together with the roof B, arched, as shown, and having an opening which is closable by the cap 6.

Subjacent to the main bod portion of the furnace are branches 0. Tliese branches C and also the hearth of the furnace are lined with the usual fire brick lining f and an inner lining (Z of burned magnesia mixed with tar and rammed in place, the lining for the roof being usually of silica brick. It will be found suitable to place the subjacent branches or legs C at an angle of say twenty degrees from the vertical, and it will be understood that the metallic frame work, water-cooled at any desired place as is customary in steel metallurgy, is suitably bound together, by its metallic plates or frame work so as to constitute a structure of the necessary inherent strength and stability.

The several legs C are provided with channels g, which channels converge upwardly toward a common central point represented by the opening in the furnace roof closed by the removable cap 6, so that, on removing the cap 6, it will be feasible, at any time, to repair the rammed lining of the channels 9 by inserting a suitable former (as, for instance, a metal rod of corresponding cross section) through the roof and into the channel 9, or from the opposite end of the said channel after removing the solid electrode h, whereupon, the tamping material may be tightly rammed about the former so as to effect a speedy and etficient repair. Ifthe rod employed is simply to subserve the functions of a former, it may then be removed from the channel, thereby leaving the channel open forthe reception of molten metal from the bath when the charge is poured in; but, in some instances, the former may consist of the electrode h itself if the electrode is of such material (preferably that of the bath) that on the passage of the current it willbecome liquefied as indicated in Figs. 1 and 4.

The tamping of the hot mixture of burned magnesia and tar employed for making the inner lining D of the hearth and the subjacent legs is preferably rammed by-means of the well known pneumatic rammer, and it will be understood that in thus making the inner lining, {the portion of said lining occupying the subjacent legs C is first inserted, and that, when this portion has been brought to the level of the bottom of the hearth, the remainder thereof is firmly rammed in place to form the hearth bottom and sides. ater-cooled bronze collars i are now firmly attached to the electrodes h, which electrodes may conveniently be made of iron. The molten metal which is to serve as the bath 0 in the furnace is then poured upon the hearth and to the working depth required, and this molten metal enters the channels in the subjacent legs C at a tem erature sufficient to enable it to reach the ottom of the channels and make electric connection with the electrodes h. The three electrodes it being connected up with the leads of a three-phase alternating current, the current employed is to be so chosen as not only to bring the metal in said channels to the desired molten condition, but also to produce the pinch phenomenon therein. This pinch phenomenon will exhibit itself at a short distance below the entrance to the hearth and will thereupon cau'se a disruption of the column of metal. Thereupon, owing to the hydrostatic pressure of the bath, the column is immediately reestablished, a new contact being made, and without oxidation, inasmuch as the conditions prevailing at the locus of the pinch effect are reducing. A good electric contact is, therefore, made as often and as soon as abreak takes place, and the alternate series of disruptions and contacts thus produced result in a series of pulsations or impulses. These impulses or pulsations effect a thorough mixing of the metallic bath, thereby increasing the efiicency of the chemical reactions and shortening the time of the operation, and the same-phenomenon is reproduced in eaclrof the three legs or branches, to the corresponding advantage of the operation.

For the treatment offj steel, such as, for instance, steel which has been decarbonized to the usual extent met with at the termination of the blow and the disappearance of the carbon flame in the Bessemer converter and which has thenbeen poured into the electric furnace, the current employed will usually'be of low voltage and of high amperage, so as to develop the required large number of amperes (say from 1000 to 3000) per square inch, necessary to develop the pinch phenomenon, at the hottest point of the molten metal column as against the countervailing hydrostatic head. By suit.- ably regulating the amperage of the current with respect to the hydrostatic head, until the impulses or pulsations manifest themselves, in the bath, the o erator will be able to obtain the desired e cot and to regulate its value and intensity. So also, if it is desired 'to give a rotary motion to the bath, the channels in which the metal g is contained maybe so built as to have their axes in planes inclined to the vertical axis of the hearth, so as to set up a corresponding whirling motion. The usualmetallurgical reactions having been effected and the quality of metal being satisfactory, the furnace is tapped if stationary, or tilted if tiltable, as desired, or at least until the tubular channels are exposed. In carrying out the metallurgieal reactions, the metal may be deoxidized, desulfurized, dephosphorized, 0r otherwise purified, and then converted into steel by the usual additions, all as is well understood in the art.

If, after the furnace has been tapped, an examination reveals the'necessity of repairs, the modus opcramlz' is as follows: Through the side doors of the furnace and through the opening in the roof, (closed during active operations by the cap 6), a pneumatic chipping tool is introduced and the eroded portions of the magnesia lining (Z are re moved. In the meantime, if the metal 9 in the channels of the legs C has been permitted to remain, it will have solidified therein to such an extent that, by means of hydraulic jacks or the like, pressure applied to the electrodes It will force the solidified metal 9 upwardly until its extremity is slightly above the bottom of the hearth, the electric connection and water-cooling block i having first been removed, if necessary. A fresh mixture of magnesia and tar is then thrown into the furnace around the ends of the solidified metal projecting from the channels, and is rammed tightly in place by a pneumatic rammer, the sides and bottom being likewiserepaired by a similar mixture. I In case the furnace has been tilted to such an extent as to drain the molten metal 9 from the channels, the necessary repairs to the lining of the channels may be eflected by inserting the forming rod through the opening in the roof of the furnace and similarly ramming the mixture of magnesia and clay as described.

In the form of the invention shown in Figs. 4, 5 and 6, the same construction and mode of operation described with reference to the form of furnace shown in Figs. 1, 2 and 8 'is preserved with the exception that in the furnace of Figs. 4c, 5 and 6 the electrodes are adapted to be connected either to a source of direct current supply or to a source cor" inonophasealternating current supply.

In the form of the invention shown in Fig. 7, one of the current leads may be connected to the carbon electrode D. The pinch etfect, incident to the practice of my inven tion, is, as in the two former modifications shown in the remaining figures, realized as before, in the molten metal 7 contained in the channels of the depending legs; but the heating effect is reinforced by the arc established between the carbon D and the bath.

it will be understood that, in starting the furnace of Fig. 7, the electrode C may be brought into actual contact with the bath or the slag floating upon the bath, but, in

operation, it will preferably be withdrawn restablishments of the connection by the hydrostatic pressure due to the bath; sub stantially as described.

2. The method of treating a bath of molten metal in an electric furnace, which 'consists in providing the bath with a connection likewise of molten metal, and passing through said molten metal connection an electric current so proportioned to its cross section as to cause a series or disruptions in said connection in close proximity to the main body portion of the bath, alternating with a series of reestabli'shments of such connection by the hydrostatic pressure of the bath; substantially as described.

3. The method of treating a bath of molten metal in an electric furnace, which consists in providing the bath with a connection likewise of molten metal, passing through said molten metal connection an electric current so proportioned to its cross section as to develop a series of disruptions in said conductor, alternating with a series of reestablishments of the connection by the hydrostatic pressure of the bath, and preventing oxidation of the molten connection at the place of disruption by providing reducing conditions thereat; substantially as described.

i. The method of treating a bath of molten metal in an electric furnace, which consists in providing the bath with a connection likewise of molten metal, passing through said molten metal connection an electric current so proportioned to its cross section as to cause a series oi? disruptions of the connection, alternating with a series of reestablishments of the connection by the hydrostatic pressure due to the bath, and effecting a thorough mixture of the metal in the bath by the pulsations due to said alternate disruptions and restablishments; substantially as described.

5. The method of treating a bath of molten metal in an electric furnace, which consists in providing a bath with a multiple connection likewise of molten metal, and passingthrough the said multiple connection a. multi-phase current so proportioned to its cross section as to cause a series of dis ruptions of the connection, alternating with a series of reestablishments of the connection by the hydrostatic pressure due'to the bath; substantially as described.

The method of treating a bath of molten metal in an electric furnace, which consists in providing the bath with a connection likewise of molten metal, establishing an electric are above and out of contact with the bath and passing across the arc and through said molten metal connection an electric current so proportioned to the cross section of the molten metal connection as to cause a series of disruptions of the connection, alternating-with a series of reestablishments of the connection by the hydrostatic pressure due to the bath; substantially as described.

T. The method of treating a bath of molten metal in an electric furnace, which consists in providing the bath with a multiple connection likewise of molten metal, establishing an electric are above and out of contact with the bath and passing across the arc and through the molten metal multiple connection a multi-phase current so proportioned to the cross section of the multiple molten metal connection as to cause a series of disruptions thereof, alternating with a series of restablishments of the connection by the hydrostatic pressure, due to the bath; substantially as described.

8. An electric furnace provided with a hearth for containing a bath of molten metal, subjacent branches depending from the hearth and having channels communicating therewith, said channels being so proportioned with respect to the working capacity of the hearth that, upon the passage of the predetermined current necessary for treating thebath of metal thereon, there will be produced a series of alternate disruptions and reestablishments of connection in the molten metal contained in said channels; substantially as described.

9. An electric furnace provided with a hearth for containing a bath of molten metal, subjacent branches depending from the hearth and having channels communicating therewith, said channels being upwardly and inwardly inclined, and a furnace roof accessible for repair; substantially as described.

10. An electric furnace rovided with a hearth for containing a ath of molten metal, subjacent branches depending from the hearth and having channels communicatin therewith, said channels being upward y and inwardly inclined, toward a common center, and a furnace roof having a closable opening through which all of said channels are accessible for repair; substantially as described.

11. An electric furnace, provided with a hearth for containing a bath of molten metal and having subjacent branches upwardly and inwardly inclined toward a common center, a permanent lining for said hearth and branches, a su plemental tamped lining, and a furnace roof through which, with the cooperation of a suitable former, repairs to the tamped lining may be made; substantially as described.

12. In an electric furnace, the combination with a hearth for containing a molten metal bath, of subjacent branches depending therefrom, said branches containing upwardly and inwardly extending channels communicating with the hearth, a furnace roof, and a closable o ening in said roof throu h which a suit le former may be passe into any of the channels so as to permit their wall lining to be made and repaired by tamping; substantially as described.

In testimony whereof I afiix my signature,

- in presence of two witnesses.

AUGUSTIN LEON JEAN QUENEAU.

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