US1478986A - Process for the manufacture of artificial charcoal - Google Patents

Description

Patented Dec. 25, W2.

UH g

JACQUE CYRUS MOB/BELL, OF NEW YORK, N. Y.

PROCESS FOR THE MANUFACTURE OF ARTIFICIAL CHARCOAL.

No Drawing.

To all whom it may concern Be it known that JACQUE C. MoRRELL, a citizen of the United States, residing at New York, in the county of New York and State of New York, has invented certain new and useful Improvements in Processes for the Manufacture of Artificial Charcoal, of which the following is a specification.

The present invention relates to the manufacture of artificial or synthetic charcoals such as are used for the adsorption and removal of impurities from air for res iration, and in various industrial and la oratory processes as the de-colorizing and purifying agent.

It relates more particularly to the preparation of a mixture of carbon material and a binder which mixture is subsequently treated in the ordinary methods or in such methods as are set out in my co-pending application Serial No. 284459 filed March 22, 1919, for artificial or synthetic charcoal and processes ofproducing the same.

Heretofore inpreparing mixtures of carbon material and a binder, difliculty has been experienced in obtaining thorough distribu-, tion of the binder throughout the body of finely divided carbon material. This is readily recognized when it is considered that the only binders suitable for such purposes are materials like pitch, which are either very viscous or very solid at ordinary temperatures. I

In my co-pendin application above referred to, I have escribed one method of accomplishing this distribution of the binder by suspending the binding material in the form of an emulsion or suspension in a very fluid medium, such as water. The present invention has to do with a process of accomplishing a similar result in a different manner. The carbon material used in the present process is preferably carbon-black or lamp-black but such others materials .as ground coke, coal, and Wood charcoal may be used. The binder that is to be used is pitch, or such materials as coal tar, bitumen and asphalt.-

It will be readily realized that mixing such binding materials with such carbon materials as are mentioned is very difiicult, and since uniformity of distribution of the binder has a marked effect upon the porosity and uniformity of' the charcoal, this question of properlyincorporating the binder is vital.

Application filed July 31, 1919. Serial No. 314,501.

The incorporation of the binder with the carbon material is accomplished in the present process by dissolving the binder in a suitable solvent, then intimately mixin the carbon material and this solution, an subsequently distilling off from the mixture the solvent material, leaving deposited u on the individual particles of the carbon a 1m of the binder. It may be remarked that such a process produces a material of which substantially each and every particle of the carbon material carries such a film of binder.

Suitable solvents for this purpose are benzene, solvent naphtha, toluene, xylene, carbon tetrachloride, low boiling point paraffine oil, or other suitable solvent Whose boiling tpoint is lower than the point at which the inding material begins to coke.

An example of one process involving the present invention is as follows (parts being, by weight) About ten parts of the binder, such as soft coal tar pitch (made by mixing a heavy coal tar oil and hard pitch in suitable proportions) is dissolved in a solvent such as.

enzene, usin from about twenty to about forty parts 0% the latter, depending on the carbon material to be used. Such carbon materials as carbon-black and lamp-black require a greater bulk of solution than heavier material.

The carbon-black (twenty or thirty parts) or other carbon material, is then thoroughly mixed with the solution.

The thin paste resulting from the above step is then placed in a suitable apparatus and the solvent distilled ofi and recovered, the temperature being controlled so as to remove only the solvent. The residue consists of the carbon material, the individual grains of which are coated with the film of the original binding material.

The product obtained by the above process can be readily compressed into a solid and subsequently treated in a fashion such as is described in my co-pending application above referred to. To accomplish the compression,

this product is placed in'a mold consisting of a sleeve, plunger and plug which is heated to about 90 C. and compressed with a pressure of 32,000-60,000 lbs. per square inch. Any substantial pressure, however, will suffice. The quality of the product improves with increase in pressure up to a certain point. The function of molding under pressure is a very important one, determining to a large extent the nature and quality of the finished product. The best types of charcoal possess a large degree of porosity and have supporting walls which are most dense. These are the qualities which molding under pressure gives the finished product. Also, the pores and ducts of the carbon should be of the continuous or spongy type. If the residue is heated without first molding under pressure a large proportion of the ducts are discontinuous and the product is friable because the walls are not sufliciently dense. In large Scale work a rotary press, whose molds pass through a heated zone, may also be used.

The temperature to which it is necessary to heat is dependent upon the melting point of the pitch which in turn is dependent upon thepercentage of oil in the mixture and the conditions can be controlled to allow compression in the cold and the pressure may be varied within wide limits depending on the final product desired.

The crude charcoal from the press is crushed and ground to from 8 to 10 mesh or any desired size. The grindings are utilized for regrinding to a powder after which they are recompressed without any other additions to produce charcoal. The ground material is introduced into a furnace and gradually brought to the decomposing temperature. Schedules of 4 hours at 850 C. then to 925 C. for one-half hour, and of 3 hours at 925 C. to 950 C. have proved satisfachave found that a final heat treatment following the above steps causes a marked improvement in the efiiciency of the charcoal. This is true not only of synthetic charcoals but also of other charcoals as for instance, standard cocoanut charcoal which showed an improvement of 50% in activity after this treatment. The apparent density of the charcoal after this treatment. shows a pronounced lowering which, it is thought, is caused by the internal oxidation by adsorbed air or the removal of hydrocarbons or both, by this heat treatment. Heating beyond a certain length of time in the first carbonization treatment causes little improvement in the charcoal. However, if the charcoal is allowed to cool to about 250 0., removed from the furnace and cooled in the air to room temperature to prevent the adsorption of hydrocarbons by the charcoal, upon a second heat treatment, the above described results take place. Since the walls of the furnace contain condensed hydrocarbons, the second heating is done in a different furnace (though if cleansed one furnace will suffice). The conditions under which this heat treating process is carried on should be at about 850 C. to 950 C. for about 2 hours. A third heat treatment also shows beneficial results. Heating in the presence of steam and other-mild oxidizing 1 ,avaeae agents also produces beneficial results. This may be done by any well known method, for example, by introducing steam directly into the retort.

The carbon-black-binder mixture produced by the above process is a black powder which flows almost as readily as the original dry carbon-black, and advantage is taken of this fact in carrying out a modification of the above described method, which modification also permits the accomplishing of a very desirable object.

In the distillation of crude tars and oils, such as coal and pine tars and petroleum oils, for the purpose of recovering the valuable low boiling components, much trouble is occasioned by the accumulation of the pltch upon the walls of the distillation apparatus. This pitch forms a thick lining which acts as a heat insulator, incidentally increasing fuel cost, and it is necessary at frequent intervals to interrupt the distillation process in order to remove this disturbing factor. The ordinary method of removal is to allow the apparatus to cool and have the pitch chopped away by hand.

Since the carbon-black binder mixture produced as described above is pulverulent and has the property of flowing readily, it is proposed to utilize this property in preventing the accumulation of pitch upon the walls of the distillation apparatus or retort. This may be readily done by adding to the crude tar or oil about to be distilled an amount of carbon-black or other carbon material which corresponds to the amount of pitch which will be produced by distilling the tar or oil and distilling the mixture. It will be found that the pitch and carbonblack may be readily raked out of the retort without the necessity of cooling the apparatus and without difiiculty.

The pitch resulting from such distillation remains adsorbed upon the carbon-black or other carbon material and this mixture may then be treated in the same manner as the mixture produced by the first process herein described.

The present invention, therefore, contemplates intimately mixing carbon-black or other carbon material with a material which contains pitch and a low boiling solvent or a material which contains the constituents of such pitch and solvent and from which pitch and solvent may be produced by distillation.

By the term carbon as used in the claims, I propose to include pure carbon of natural or artificial origin or a mixture of natural or artificial origin which contains a high percentage of carbon; also various charcoals of animal, vegetable or mineral origin.

It should be noted that the present invention is not limited to the exact details and depending upon the exact materials used,

but is to be limited only by the appended claims.

Claims: I

1. In a process of making built-up structural adsorbent charcoal, mixing carbon in a finely divided condition with a solution in a low boiling solvent of a binder which chars on heating, distilling off the solvent, molding the residue under substantial pressure, charring the binding material therein and then activating by heating.

2. In a process of making built-up structural adsorbent charcoal, mixing carbon in a finely divided condition with a solution in a low boiling solvent of a binder which chars on heating, distilling off the solvent, molding the residue under substantial pressure, comminutin the molded material and charring the bindm material therein and then activatin by eating.

,3. n a process of making built-up structural adsorbent charcoal, mixing carbon in a finely divided condition with a solution in a low boiling solvent ofa binder which chars on heating, distilling 03 the solvent, molding the residue under substantial pressure, charrin the binding material therein and then activating by heating and treatment with a mild oxidizing agent.

4. In a process of making built-up structural adsorbent charcoal, mixing carbon in a finely divided condition with a solution in a low boiling solvent of a binder which chars on heating, distilling off the solvent, molding the residue under substantial pressure, comminutin the molded material and charring the bindlng material therein and then activating by heating and treatment with a mild oxidizing agent.

5. In a process of making built-up structural adsorbent charcoal, mining carbon in a finely divided condition with a solution in a low boiling solvent of a binder which chars on heating, distilling ofi the solvent, molding the residue under substantial pressure, charring the binding material therein and then activating by heating and steaming.

6. In a process of maklng built-up structural adsorbent charcoal, mixing carbon in a finely divided condition with a solution in a low boilin solvent of a binder which chars on heating, istilling off the solvent, molding the residue under substantial pressure, com minuting the molded material and charring the binding material therein and then activating by heating and steaming.

7. In a process of making built-up structural adsorbent charcoal, mixing carbon in a finely divided condition with a solution in a low boiling solvent of tar pitch, distilling off the solvent, molding the residue under substantial pressure, charring the binding material therein and then activating by heatmg. g

8. In a process of making built-up structural adsorbent charcoal, mixing carbon in a finely divided condition with a solution in a low boiling solvent of tar pitch, distilling oil the solvent, molding the residue under substantial pressure, comminuting the molded material and charring the binding material therein and then activating by heating.

9. In a process of making built-up structural adsorbent charcoal, mixing carbon in a finel divided condition with a solution in a low oiling solvent of tar pitch, distilling oil the solvent, molding the residue under substantial pressure, charring the binding material therein and then activating b heating and treatment with a mild oxidizing agent.

10. In a rocess of making built-up structural adsor ent charcoal, mixing carbon in a finely divided condition with a solution in a low boiling solvent of coal tar pitch, distilling oil the solvent, molding the residue under substantial pressure, comminuting the molded material and charring the binding material therein and then activating by heating and treatment with a mild oxidizing agent.

11. In a process of making built-up structural adsorbent charcoal, mixing carbon in a finely divided condition with a solution in a low boiling solvent of coal tar pitch, distilling off the solvent, molding the residue under substantial pressure, charring the binding material therein and then activating by heating and steaming.

12. In a rocess of making built-up structural adsor ent charcoal, mlxing carbon in afinely divided condition with a solution in a low boiling solvent of coal tar pitch, distilling oil the solvent, molding the residue under substantial pressure, comminuting the molded material and charring the binding material therein and then activating by heating and steaming.

In testimony whereof I aflix my signature.

JAG CYRUS MORRELL.