US1836880A - Electrode - Google Patents

Description

M. 0. SEM

ELECTRODE Dec. 15, l 931.

Filed Jan. 16, 1928 v 1 4 MW fffllflfll 1,1,! mw/%/rI!ffl /M I r'fffff'"! flll/ '//U "/44 rfI/Md' lM/fIl/Il' m 4/!!! 6 a Doc. 15, 1931 UNITED STATES PATENT; OFFICE IATHIAB OV'BOI BEE, OI BUFFALO, NEW YORK, ABSIGNOB '10 DE! N038 AK'I'IESEL-' m1: 1'03 nI-nxraomxsx INDUSTBI OI NORWAY, OI OSLO, NORWAY Emio'rnonn Application fled January 18, 1888, Serialll'o. $47,241, and in Norway January 15, 1 927.

This invention relates to electrodes which are baked while in use in the electric furnace. Such electrodes are generally provided with 'a metallic casing, whlch acts as a mould 5 for the electrode and at the same time transmits'the current to the baked part of the electrode. In certain cases such a metallic casing has various drawbacks which require special precautions. The object of the present invention is a casing which eliminates 16 contamination is'so small that it nee of aluminum special precautions must be taken to prevent contamination of the rod uct. This may be avoided by employing a mantle consisting of aluminum. If the contacts are clamped to the external sides of the electrode as is common practice with selfbaking electrodes I have however found that such a mantle cannot be employed as there will be a voltage drop of 0.3-0.5 volt between contact and aluminum mantle. As the total furnace voltage is only 6 volts the said voltage drop is a serious drawback which must be eliminated if first class results are wanted from the electrode. Also in the use of mantles of other material there will be a certain voltage drop and I have therefore found that in such cases it is often advantageous to do entirely without the metallic mantle. U. S. A. Patent No. 1,442,031 describes a modification of self-baking electrodes in which the metallic mantle may be avoided. When employing the procedure described in this patent certain difiiculties are found which are more or less prevalent in the difierent types of electrode mass used and according to the various other conditions under which the electrode works. As shown in the patent it is necessary to give the electrode an armature which moulds the electrode and keeps it together until it is sufliciently baked to do without support. This armature often has the shape of a casing into the upper end of which the electrode mass is filled and whose 'This layer will then lower end is connected with a combined electrode holder and cont-act arrangement. The baking must then be effected in such a manher that the holder will be situated on a baked part of the electrode.

When using electrodes of thetype above described it is found that the aste has a tendenc to stick to the surroun ing casing and to t e contact. This is especially noticeable if the electric current after the lowering of the electrode in the holder must pass throu h a layer of electrode paste which is not ba ed. very rapidly become baked while its organic binders (generally tar and pitch) are coked and the paste will thus stick so tightly to the contacts that the electrode can only with difiiculty be lowered when this again becomes necessary to compensate for the electrode consumption in the furnace. Also in the upper part of the guiding casing is found that the paste easily sticks and its upper part will more or less remain in the guiding casing without following the electrode down into the furnace. This latter phenomenon may however be avoided by placing metallic rods, wire or netting of suitable composition in elec- 'trode paste whereby the upper oi the. paste 13 better connected with the lower part.

The method of working will however be quite satisfactory unless the present invention is used and the electrode mass is stir rounded by a coatingp-rei erably non-inetallic coatingwhich may suitabl consist of organic substances or the like which prevent the sticking. This coating may be employed in the form of a casing consisting for instance of wood, veneer, cellulose card board or the like which envelopes the electrode. The said materials may be employed alone or impregnated with substances which prevent saturation with tar as for instance water glass or glue. The non-metallic casing must be of such strength that the paste is held together without the use of a special external guiding mantle. In many cases it is however advantageous to employ a guidin mantle which may be metallic or non-me allic. 'A composition of graphite and oil or cardboard impregnated with said mixture may then also is greatly facilitated.

be employed. This composition may also be applied on the guiding mantle before the electrode mass is filled in. The composition will then form a layer of graphite around the electrode whereby the lowering of the electrode non-metallic casing may at the same time act as a heat insulatorfor the electrode and must then of course be made with due regard to this fact.

If in the manufacture of such a non-metallic casing inorganic compounds are employed which increase the resistance between the electrode contact and the baked electrode it may be advantageous to make the electrode holder in such a way that it will 'automatically remove the non-metallic coating surrounding the electrode when the electrode is lowered through the holder. This may be done for instance as taught in Patent 1,657 ,948

'to Westly.

I have made thorough investigations with this method and have found that the sticking as already mentioned above is especially prevalent if the current is supplied to the electrode in such a manner that the current will tion if electrode holder and contact are made in such a wa that the cooling of the electrode becomes neg igible. It is then suitable to employ a contact which is allowed to run hot, allowing the electrode mass to become baked all the way out towards the contact. It is preferable to let the contact become red-hot and it should therefore be made of a temperature-resistant metal, for instance nickelchromium or the like.

An electrode as mentioned above has the drawback that it will become red-hot under the holder and the action of the air will then easily cause consumption of the electrode. Such consumption may however be avoided in the modification shown in Fig. 1, where the electrodeis surrounded by a mantle entirely enveloping the electrode and only being open downwardly. In this way oxidizing air may be prevented from reaching the electrode between the clamps. 1 is a selfbaking electrode having a casing 1a of organic substance, 2 is the enveloping mantle, 3 is a contact clamp, 4 is current supply.

This modification also has an advantage in that the electrode will only draw very small amounts of heat away from the electric furnace for which reason the efiectivity of the electrode in the smelting furnace is very good.

An electrode made in this way may only be lowered comparatively short distances at 1,sse,aeo

a time as otherwise unbaked mass will enter the contact thus causing the above mentioned drawbacks and also increasing the chances holder clamp. As will appear from the drawings contacts are used which are placed above the electrode holder and which if desired may be so made that they can be moved independently of the said holder. The electrode baking may then be regulated by regulating the distance between contact and holder and difiiculties due to adhesion between unbaked mass and contacts need not be feared, especially if the contacts are so made that they may be moved independently of the holder.

What I claim as new and desire to secure by Letters Patent of the United States is:

1. Electrode which is baked while in use in the electric furnace comprising raw electrode mass, a non-metallic casing for said mass and a mantle surrounding said casing, said mantle having contact members and gripping members, the contact members being placed above the gripping members and electrically insulated therefrom.

2. An electrode which is baked while in use in an electric furnace comprising raw electrode mass, a mantle surrounding the electrode. contact members for the electrode, and gripping members therefor, the gripping members being electrically insulated from the contact members.

3. An electrode which is baked during its use in the electric furnace, comprising raw electrode mass. and a casing of organic substance enveloping said electrode mass adapted to hold the material of the mass together and prevent sticking of the electrode to a holger in connection with which it may be use 4. An electrode which is baked in a furnace in which it is used, comprising raw electrode mass, a casingfi of organic substance in which said mass is contained. and an outer metallic casing surrounding the first said casing and separated by the latter from the electrode mass.

5. An electrode which is baked while in use in the electric furnace comprising raw electrode mass, a casing made up of organic material in which said mass is supported and contained, an outer metallic casing surrounding the first said casing, and a clamping arrangement carried by the said outer metallic v in an electric furnace comprising a casing of organic material having electrode mass contained therein, said casing being impregnated with a substance for reventmg saturation of the casing by the bmder of the electrode mass, and a metallic casing surrounding the first said casin MATHIE'S OVROM SEM.

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