US1215700A - Carbon electrode and method of manufacturing same. - Google Patents

Description

UNITED STATES. PATENT omen.

ROBERT D. PIKE, OF SAN FRANCISCO, CALIFORNIA.

cnanoifnrncraonn AND warrior or muracrumnc sum- No Drawing.

To all whom it may concern:

-Be it known that I, ROBERT D. PIKE, a

citizen of the United States, residing in the manufacture of illuminating gas from petroleum possess certain qualities lacking in the ordinary carbon electrodes, noticeably a denser structure freer from porosity and a higher degree of electric conductivity.

The former feature is not possessed by any other carbon electrodes made from materials as cheap as this refuse lamp black and the latter quality namely of electric conductivity is not possessed in such high degree by any other carbon electrodes used for these purposes. These qualities are of advantage, in that less of the material being treated is absorbed by a dense carbon than by a porous carbon and there is less tendency for the carbon to disintegrate and the higher electric conductivity enables more electricity to be conducted to the work for a given weight of electrode. Inasmuch as refuse lamp black is a very cheap by-product produced in reat abundance wherever illuminating gas is manufactured from pctroleum, as in California and Oregon, I am able to produce electrodes of superior quality at a very low cost.

By the term lamp black refuse as employed herein is not meant lamp black in the true sense commonly employed, '2. e.

finely divided carbon deposited from smoke or smoky flame. On the contrary, the lamp black refuse from gas plants is neither a true lamp black nor a true coke, but, in realit is a distinct form of amorphous carbon, being just as distinct from either the coke or true lamp black as these two latter differ from each other.

True lamp black is a product containof illuminating gas, tar and re Patented Feb. 13, 1917.

Application filed larch 18, 191.6. Serial No. 88,788.

ing no impurities; as produced it is ractically purecarbon. It is this form 0 lamp black which has heretofore been employed 1n connection wit the manufacture of electrodes and carbo 1 Q Refuse lamp black is one of the byproductsderived from the manufacture of illuminating gas from petroleum, and the manner of its production is, inbrief, the spraying of petroleum, air and steam upon red hot fire bricks in an inclosed'space or i chamber, resulting in a molecular re-arrangement, and the consequent fproduction use lamp black; the last named is separated from the gas by passage through cold water. The temperature of its formation is high, the

gases carrying the'refuse lamp black in suspension having a tem erature of approxi-' mately 1800 degrees Falin, before plunging into the cooling water which precipitates the so-called lamp black. This so-called refuse lamp black is gritty and when dried and purified is'a steel gray color, and when examined under a high power microscope discloses a different characteristic structure of particles from true lamp black. The name lamp black as indicating a refuse by-product from gas manufacturing plants, is em loyed by those connected with the manu acture of gas to designate such byproduct for lack of a more expressive term. True lamp black is lighter in weight; the weight of a cubic inch of true lamp black is about of an ounce, whereas the Wei ht of a cubic inch of refuse lamp black, a er being purified and dried, is about .42 oz.

I have found that the so-called lamp black refuse from the manufacture of illuminating gas from petroleum, per hundred pounds contains the following in about the proplortions given T ree pounds of soluble and insoluble ash, 0IWh1Cl1 two and one-half pounds is solu e: I

In carrying out my process for the manufacture of carbon electrodes from the mentioned lamp black, the first of the im-.

purities be eliminated is the tar.

For th1s purpose the mass of refuse matcertain portion of the tar may be added ter is subjected to hot water washing and milling, in what is known as a chaser mill or wet pan. This operation, wh 1ch 1s carried on for a period of approximately twenty minutes agglomerates the tar Into pellets about the size of a pea and flatwafers, which is separated by washlng 1n a screen of suitable mesh. The resultant product is finely divided lamp black, which is treated for the elimination of soluble ash by any suitable washing apparatus, wherein the washing is done with successlve charges of water, each charge being drained off for washing away the soluble ash. The material with the soluble ash eliminated therefrom is then treated in a roaster or.

drier, wherein it is agitated while subjected to atemperature of approximately 1000 degrees Fahn, for the removal of all moisture and the high volatile hydrocarbons. This roasting operation is continued for approximately three hours, after which the material is in a dry powdered form, but still contains a trace of hydrocarbon volatiles and from five to ten per cent. by weight of occluded air. To eliminate such volatiles and the occulated air, the material is then charged in fire clay muifles and subjected to a bright red heat at a temperature of between 1800 degrees to 2000 degrees Fahn, and subjected to such roasting for approximately eighteen hours. The resultant product is a gray substance partaking of the qualities of a coke of a high degree of purity and also of a lamp black, though not so fine in grain as the latter, containing approximately one quarter of one per cent. of volatile matter and one half percent. of insoluble ash.

I have found that from certain gas plants a refuse lamp black is obtainable free from soluble impurities, in which case the process for washing these out may be eliminated. I have also found that in certain cases where it is desirable to have an electrode with a high degree of tensile strength rather than an extreme fineness of grain, a

before the material is roasted in the fire clay muflies.

After the material has become cool it is ground in a' suitable mill and reduced to a fine powder, which is run through separators to remove ironparticles which may be contained therein and thereafter there is intermixed therewith a suitable quantity of coal tar or coal tar pitch and oil toact as a binder for the placing of the mixture in a plastic condition, and the same is then compressed into cylindrical cakes. These cakes are formed into green carbon sticks, which are baked in the usual manner for forming carbon electrodes.

The carbons produced from the so-called lamp black refuse of the plants manufacturing illuminating gas from petroleum have proved to be more efficient than the carbon electrodes at present, in use.

Practical experiments have demonstrated that carbons or electrodes manufactured in accordance with the described invention have a current carrying capacity of about ten per cent. (10%) higher than carbons or electrodes asat present manufactured; for example, after a series of experiments covering about six months time, it was found desirable to reduce the size of the carbons or electrodes from g standard to and when so reduced the cross sectional area of the improved carbon or electrode had equiv 'alent properties with other carbons with crossssectiona'l areas about ten per cent. (10%) greater. When the improved earbons or electrodes were in the full size of 5 they would not operate to the best advantage, as they were underloaded when subject to the conditions which are considered standard for use of g electrodes.

Another dilference in favor of the improved carbon or electrode found to exist over thestandard form of carbons or electrodes in general use, probably based upon their ability to carry a high amount of current, is the characteristic which they possess of carrying an are free from hissing, when subjected to very high currentsand with a shortair gap between the electrodes, the improved f in diameter when carrying from 40 to 42 amperes direct current producing a perfectly quietarc with a short air gap; whereas, under like conditions the standard carbons at present in use causehissing and often a so-called mushroom would form on the lower or negative electrode.

These above mentioned features bearing upon both the current carrying capacity of the carbon or electrode and upon its production of a quiet are, under diflicult and unusual conditions,'are of extreme importance in determining the commercial value of the electrode.

Relative to the specific density of the carbons or electrode produced under the present invention, this can be varied over a considerable range at the will of the manufacturer by changing several different and nonessential factors in the process of manufacture, such as fineness of the dust and density of the coal tar or coal pitch. Tests have demonstrated the improved electrode to have from 10%to 20% less porosity than the standard electrodes at this time placed.

ture theaters, spot lights, etc. There isno difference, however, in the manufacture in the production of electrodes for use in projecting, except that it is preferable to add suitable fiuxing material to the powder before the coal tar or coal pitch is mixed with it. This flux (usually boracic acid) has a property of combining with the small remaining quantity of ash in the electrodes and being fused by heat of the are into small pellets, which drop, and, therefore, prevent the ash from accumulating in the electrodes and interfering with the arc. However, the use of such av flux is in no way essential and may be dispensed with, either when applied to the production of carbon electrodes for use in electro-chemical indus try and dry batteries, or for use in project ing machines.

The so-called illuminating gas, which is usually the main product of manufacture when refuse lamp black -is produced, can be used, of course, for other purposes than as an illuminant, that is in gas engines or as a fuel for firing kilns, boilers, etc. It is,

therefore, possible and the scope of this invention contemplates such a possibility for the manufacturer of carbon electrodes to produce his own refuse lamp black, utilizing the illuminating gas produced for the purpose of firing kilns and the generating of the power used in the factory. The advantage of this method of manufacture would be principally a high degree of control over the quantity, and, in a certain degree, over the quality of the refuse lamp black produced, for its quality is dependent almost entirely upon the degree of care exercised in preventing its admixture with outside impurities, whose presence is in no way essential to the process of the manufacture of illuminating gas.

I am well aware that true lamp black has heretofore been utilized in connection with the manufacture of electrodes, and 1 therefore do not wish to be understood as claiming the use of such material, but, on the contrary, confine the invention to the use of a so-called lamp black refuse derived from plants manufacturing illumlinating gas; and this irrespective as to whether the manufactured gas be utilized for illuminating, heating or power purposes.

Having thus described the invention what is claimed as new and desired to be protected by Letters Patent is 1. As an article of manufacture, a carbon formed from lamp black derived from the waste by-products of the manufacture of oil gas, and a carbonaceous binder intermixed therewith.

2. The method of producing carbon electrodes from the refuse lamp black? product of the manufacture of gas, which consists in eliminating from said product foreign impurities, thence forming the material into a plastic body, thence producing green sticks therefrom and finally baking said sticks for the production of carbon electrodes.

3. The method of producing carbon electrodes from the lamp black refuse derived from the manufacture of gas from oil, which consists first in eliminating therefrom by washing the tar contained therein, thence removing the soluble ash, thence roasting under agitation for the removal of moisture and the high volatile hydrocarbons, thence roasting at a higher temperature for the elimination of remaining hydrocarbons, thence reducing the material to a powder, adding thereto a suitable flux and forming the whole into a plastic body, thence forming the same into green carbon sticks and finally baking the same for the production of the required carbon electrodes. I 4. The method of' producing carbon electrodes from lamp black refuse derived from the manufacture of gas from oil, which consists first in eliminating from the material by washing and roasting the impurities contained therein, thence forming the material into a plastic body, thence producing green sticks therefrom and finally baking said sticks for the production of carbon electrodes.

5. The method of producing carbon electrodes from lamp black refuse derived from the manufacture of gas from oil, which consists first in eliminating from the material by Washing and roasting the impurities contained therein, thence reducing the material to a powder having incorporated therein a suitable flux, then forming the material into a plastic body and producing therefrom green sticks, and finally baking said sticks for the production of the carbon electrodes.

6. The method of producing carbon electrodes which consists in separating from the carbonaceous refuse product of gas manuproduction of electrodes.

8. The method of producing carbon electrodes, which consists in separating the volatiles from the waste bfy-products of the In testimony whereof I have signed my, manufacture of oil gas or the recovery name to th1s spec1ficat1on in the presence of therefrom of the so-called lamp black, retwo subscriblng witnesses.

ducing the same to a finely divided condi- ROBERT D. PIKE. 5 tion, intermixing therewith a carbonaceous Witnesses: V

binder, and thence baking the same for the N. A. AOKER,

. produetion of cal-bone. D. B. RICHARDS.