US1441037A

US1441037A - soderberg

Info

Publication number: US1441037A
Authority: US
Publication date: 1923-01-02
Anticipated expiration: 1940-01-02

Description

Lian. 2, 1923. 1,441,037.

a C. W. SODERBERG.

PROCES 0F BAKING CARBON ELECTRODES.

FILED uc.4.19n. -2 suzns-suzn mm! W Inventor, Carl Wilhelm SbderbQrg y M Attorneys 2 SHEEIS-SHEEI 2.

C. W. SODERBERG.

PROCESS OF BAKING CARBON ELECTRODES.

' FILED DEC.4. I917.

Jan. 2, 1923.

Inventor,

Car] Wilhelm Siderberg 13 $@&

W Attorneys Patented Jan. 2, 1923.

um'ranwsra'ras PATENT OFFICE.

CARL WILHELM sonnRBERG, or 'CHRISTIANIA, NORWAY, ASSIGNQR 'ro DIET NORSKE AKTIESELSKAB son ELEKTROKEMISK nmrrs'rm or NORWAY. or cnm's'rmnra,

NORWAY.

P3061385 OF BAKING CARBON ELECTRODES.

Application-filed December4, 1917. Serial No. 205,416.

To all whom it may concern:

Be it known that I, CARL Wimmmr 860cm BERG, a subject of Norway, and' a resident of Christiania, Kingdom of Norway, have 5 invented certain ;new and, useful Improve-z ments in the Processesof BakingCarbon Electrodes, of which the followings a speci is an improved; process for manufacturing the same and the electrode obtained there-.

by, V i

Electrodes for the. purpose abore mentioned are generally made from some carbonaceous material such as coal, coke, graphite, etc. -The material or materials select-, ed are reduced to the. desired fineness and mixed with a. suitable binder such as;tar.or pitch. The mixture is then moulded to the desired form and baked in a suitable furnace until the volatile products are driven off and the electrode has the desired density,

and conductivity.

,The raw. electrodes have a com aratively high resistance and are not con uctive to any appreciable extent. The resistance,

however depends somewhat upon the materials employed in the manufacture; for instance, an electrode of course graphite will have a higher conductivity, than-one composed of other carbonaceous materials. In

most cases the raw electrode will have a conductivity about 10000 times lower than it will have in the finished state.

Many attempts have been made to bake electrodes by means of the heat generated within the electrode itself when made a part of an electric circuit. but on account of the high resistance of the raw electrodes, this method has been found to be impractical.

According to my invention thisdiiiiculty is overcome by baking and rendering the electrode conductive in a part of its cross-section by means of heat electrically generated in a conductor connected in parallel with the electrode. This conductor may consist of metal or of a baked electrode. Preferably it is one or more iron bars inserted in" the electrode itself.

As will be understood from the following examples my method is susceptible ofmany variationsall of which embody theprocess above outlined. For instance, electrodes may be baked in a special electric furnace or thebaking may be carried on simultaneously with the use of theelectrode itselfin the furnace in whichit is mounted. In the.lat ter case a portion of the baking is accent-.1 plished by the heat of the furnace ingwhich the. electrode is employed.

In either of the instances citcd' -the electrode may be of the same. construction and made in the samemanner. A -mould maybe employed inthis process: in which is preferably mounted. a core of. conductiye material, such as a rod ofironindiameter,

for example. 1}". or a small carbonaceous electrode. The raw materials for-the elec trode are tamped around the core in the. usual manner and the mould removed-as,

15 e e-1 ployed for the baking of the electrode, the,

will bereadily understood. here a, separate furnace isv to raw electrodes are placed therein and are series-connected in the secondaryof a trans,-v former furnishing sufiicient current for the baking. With twenty electrodes, for example, a 400 kilowatt transformer of the voltage regulator type 'ving from. 220 to 110 volts may be used. 0 this end electrode No. 1 may be placed on a carbon-block, that is connected to one terminal of the secondary. On the top-end of the same electrodeis. placed a. short piece of carbon or graphite ,electrode of good conductivity, that will; take the current over to the top-end of electrode. No. 2. The lower end of No. 2 rests on another piece of a carbon or graphite electrode. Electrode No. 3 is placed, on the same piece of carbon or graphite. and so on, the last electrode of the series being connected to the other terminal of the. secondary. The spaces between the electrodes are then filled with fine sand or finely ground charcoal.

If the current is switched on with about 200 volts between the terminals, the ameter will immediately register about 800 amperes The current drops slightly at the start and then gradually rises to. about 2500 to 3000 amperes during a period of 24 to 36 hours as the baking of the electrodes proceeds. At the end of this time the baking is finished and the drop of potential will be about 6.

volts per electrode if thecurrent is 3000mm ]:t'|(:-. l: is p s ible to use a transformer without voltage regulation, but thepbaking will then proceed more slowly.-

The electrodes baked as above are allowed to cool before removing from the furnace. This requires about 36 hours. v

if an iron core has been employed its presence in the finished electrode v0u'ld7depend on the temperature obtained during baking. if it is dsired to bakeatfrbhi 'lfiflfl" to 1600" C. t-h e iron will obviously melt and the baked poi tiOn alone of the -electrode carry the current to complete 'thefiiaking. Generally so high temperatures are not necessary and'the'iron-rod will'be found in the electrode after the baking. 7 I

As a variation 'in the above method of baking in a separate furnace, it is readily possible if desired to make use of baked electrodes in place of an interior core. In that case the following.arrangementsof electrodes will be employed",

Thera'w electrodes and'thc ready baked electrodes are biiilt-"ilpfioget-her,,'always one raw and one'bakedelectrode close together and with top "and bottom' connected to the same conductor. At first the current will slightly conductivl'and takes part in the" transmission of current." The 'conduct ivity and the resultmg'lfeiit de'relopment increase until the raw electrode is'fihallv hiiked. The 'secpndniethod 'ofibakirii electrodes. f

to wit; by the useof the fu'rr iiiceiin which particularlyadyantageoiis wher very long electrodes ar''dsired, though obviously not limited th ereto'l fThe present type of electrode is about six feet long and to employ. tl1ese.in'-the"fui naces referred to requircs their being joined together and the present practice is to use a "fragile carboiinipplefor this purpose. Tlie .metlibd now to be con sidered not onl eliminates this difiicultyliut. in makinig nse of theclectric furnaceitself. for baking makes possible" the continuous supply o fele ctrodes \vithout shnltir rc down the furnace for'theinstallaliou of new (l.r trodes. d

This method is shonn (liagrauunatirallv in the drawings which form a part hereof and which itisdofhc understood. arc for illustrative purposes onl In these drawings i Figure l isa diagranunatir vertical sect ion of. a simple electric shaft {IH'HIKQ for the manufacture of pig-iron: and

Fig. 2 is a diagrammatic (1'()S. ':i(llltil1 of the usual type of metallurgical furnace.

The figures illustrate not only the diflvr cut t pes of furnace to which theproccssis applicable but different methods of baking the electrodes themselves. 1 V i i aii danthiacite used for making-the electrodc is filled in the funnel l and tamped around one or moreiron bars 2. The current is lcd to the furnace through one or more of thcsr -iron bars which may also serve as a. suspending means for the electrode. The iron ha rs may be corrugated or provided with small sliding on them.

As the raw electrode mass is a poor conductor, the' iro n bars initially will alone carry the whole current above the shaft and knots in order to prevent the electrode from in the upper and cool part of the shaft.

Through the heat electrically generated in the bars and the h eat'from the [smelting crucible the eleet'rode'is gradually baked and becomes conductive and will take part in the transmission of the current. Still nearer the zone of fusion-as at 3the temperature of the electrode is so high. that the iron core melts out, the newly baked carbon electrode alone carrying the current.

The metalusedfor reinforcing the electrode. need not be ironj, An metal can he used that has 'zi melting: point sumcientlv high above the temperature at which'the electrode mass becomeswgood conductor. and which has snfiic-ient mechanical strength. The reinforcing metal can thus be chosen according to the smelting process in question. they 'are employed'is heatihgelementspis In the example just dcscribedi the' entire smelting current vas'initihllj led to the'funv na ce throughthe iron core and the cross-seetion of.the -coremustdbefet'ore be large enough to carry the whole current. It is also possibleto bake'the electrode. br'a current that is onlyaffraction of the cnrrent used for the smelting operation. in this case the crossfsection of thc. iron-bars can b(' much smaller. "Fig. 2 illustrates the. cm; ployment of such "a method by the use of :1 separate transformer. l n this figure the portion 4 of the electrod uscd'fnr smelling is diagrammatically illustrated as already having been baked and as suspended from (he electrode-ho dcr 3 through which it is supplied with the working current for e.\' ample. IRON!) arupcres. from the sci-oudary 1 of the l wer transtnrlurr. The upper (1! ranportion of the clcclrode'T formed by lamp in;' the raw material ar und the iro lmrg as is readily understood. is connected in s rics with the secondary R of the upper ll 'lllF former and snppliz-tl villi a. linking r-urrcnl ull cicnl to ause slow baking; lol' cvnzzplu. about 2000 ampercs. This transformer is preferably of'low voltage and potential regulating type. As the lower portion 4. of the electrode is burned away; the electrode holderfi is shifted to the newiyimked por tion 7 of the electrode which is then used in the smelting operation.

The foregoing detailed description has been given for clear'hess of understanding and no undue limitation should be deduced therefrom, but the appended-'c'iaitns should be commied asbroadl' asf 'eiinissible' in view of the prior art;

hat I claim as" a'ttd' desire to secure by Letters Patent fthe United States is:-

1. The mcessmFbakingcarbOn electrodes which consists in connecting'a'conductor in parallel wit-lra-raw' lectrcde and applying an electric curreht whereby a-=-part ofthe raw electrode'is'baked and rendered conductive by heat electrically generated conductor an'd theJ of heacelectrically generated in conductor andin the electrode itself.

2; Therocess off-"baking electhe pp ying-auelectric current ,vmereay a part the conductor" and the-'bakiiigcontinuedby means ofheatlectr'tcallyg'eneratd in the conductor'end in-theeb'trode itself; said conductor being incorporated'with the raw electibde. V p

3. The process" of baking carbon elec trodes" which consists iir o'nflectihg ametal conductor in: parallel with a raw electrode and applying ah electric current whereby a part of the raw electrodeEis-baked and rendered conductive by heat electrically generated in the metal conductor and the baking continued by means of heat electrically generatgd in the conductor and in the electrode itsel 4. The process of baking carbon electrodes which consists in connecting a metal conductor in parallel with a raw electrode and applying an electric current whereby a part of the raw electrode is baked and rendered conductive by heat electrically enerated in the metal conductor and the aking continued by means of heat electrically generated in the metal conductor and in the electrodc itself. said metal conductor being incorporated with the raw electrode.

5. The process of baking carbon electrodes which consists in connecting an iron conductor in parallel with a raw electrode and applying an electric current whereby a partof th raw electrode is baked and rendered conductive by heat electrically generated in the iron conductor and the baking continued by means of heat, electrically generated in the iron conductor and in the elect rode itself.

(5. The process of baking carbon-"elm-- trodes which consists in connecting an iron conductor in parallel with a raw electrode and applying an electric current whereby a in I the biking" continued bv' part (ff the raw electrode is dered conductive by heat 0 era ted in the iron conductor continued trode itself.-

' means of erated 1n the iron con d baked and roll lcctricn ll genand the baking;

heat electrically gem uctor and in the elecsald iron conductor being incorpora'ted with the raw electrode.

(. The

process of baking carbon electrodes which consists in connecting a conductor in pp y conductive by the conductor and rendered heat electrically generated in and the which is baked tsimultaneousl 8. The process-of. co wasting:away of an -e trode'at-iits 0 which comprlses adding raw rial to theoppositeend of th baking said 'ra thereto.

9..'I-he process 0 wastin away bakin means of heat electrically conductor and i conductor and electrode serieswith another; cond o continued in generated in the n'the electrode itself. said uctor and electrode,

mpensating for the lectric furnace elecperatin'g end-within a furnace.

electrode matee electrode and w material afterits addition f compensating for the of an electric furnace electrode at its operating end within a furnace. which comprises-adding raw rial to its opposite material paitlly rent through-t 1e heat generated :1

end and b electrode an electrode when in use.

10. The process of trodes continuousl produci electrode man-- aking Silltl raw by passing an electric curd partly by the t the operating end of the.

ng carbon eleu y in the furnace in which they are employed, which comprises supplymg in electrode form raw together with nection therewith whereby the r dered conduct electrode material a conductor in parallel conaw electrode is we in and applying current baked and rcnpart by the heat electrically generated in the electrode itself and in part by the heat generated a end of the electrode when in t the opcral in; use.

6 process of baking carbon clec trodes for electric furnaces which consists in connecting a raw electrode rent whereby baked and rendered conductor in l and a )arallcl with a pplyin; :in electric cur a part of the raw electrode is conducti trically generated in the conductor and [lie baking continued by means cally generate electrode itself. said elect-rod d in the condu trode of an electric furnace.

12. The

of heat electricto i and in the e being the clc process of baking rarlion clcrtrodes for electric furnaces which onsists in connecting raw electrode rent whereby baked and ren trically gencr baking contin a conductor in and applying; a part of the l ated in the con ued by means parallel with :I an electric (:uraw electrode is dered conductive by heat elecductor and the of heat electriill! vullv generated in tln-v conductor and in the rent whereby a part of the raw electrode is baked and rendered conductive by heat electrically generated in the conductor and the baking continued by means of heat electrically generated in the conductor and in the electrode itself. said electrode being the electrode of an electric furnace, the electrode being continuously formed in said furnace.

14. The process of balcing carbon elec trodes for electric furnaces which consistsin connecting a conductor in parallel with a raw electrode and applying an electric cur' rent whereby'a part of the raw electrode is baked and rendered conductive by heat electrically generated in the-conductor and the baking continued by means of heat electrically generated in the conductor and in the electrode itself, said electrode being the elm? trode of an electric furnace. and said conductor being able to carry the total electric current led to the electric furnace.

15. The process of baking carbon electrodes for electric furnaces which consists in connecting a conductor in parallel with a raw electrode and applying an electric current whereby a part of the raw electrode is baked and rendered conductive by heat electrically generated in the conductor and the baking continued by means of heat eler trically generated in the conductor and in the electrode itself, said electrode being the electrode of an electric furnace, and said conductor being able to carry only part of the total electric current led to the furnace.

16. As a new and useful article of manu- 18. As a new and useful article of menufacture, an electrode baked in the furnace in whichit is used and comprising when in use a baked vportion and'a partially baked porti0n.

19. As a new and useful article of manufacture, an electrode baked in the furnace in which it is used and comprising when in use a body portion, a part of which is baked and a part'of which is unbaked, and a reinforcing member of conductive material in parallel electrical relation therewith.

20. As a new and useful article of manufacture, an electrode for use in an electric furnace comprising a body portion structurally differing at its two ends and a rein forcing member of conductive material in parallel relation therewith, the c0nductivity of the body portion being permanentlv greater at the working end thereof.

CARL WILHELM SGDERBERG.