US1936882A - Treatment of coal - Google Patents

Description

Nov. 28, 1933.

H.. J. ROSE El' AL TRETA'TMEN-T OF GOAL May 5, 1930 BY ATORZEY. y

.Patented Nov. 28, 1933 UNITED STATES PATENTOFFICE 1,936,882 TREATMENT or con.

application May 3, 1930. serial No. 449,040

1 Claim. (c1. 44-1) This invention relates to treatment of coal and more particularly to a processv of recovering coal from coal solutions. n

In our copending application Serial No. 97,467,

led March 25, 1926, We have set forth a process of dissolving coal in oils such as coal tar, water gas tar, and distillates thereof including tar oils. Coking coals are practically completely soluble in these solvents, while such materials as splint, cannel, anthracite, and lignite are much less soluble.

In the preparation of coal solutions, oil and raw coal are brought together and heated to dissolve substantially all the coal proper of the raw coal treated. The temperature employed is Such thatA solution of the coal in the oil takes place without decomposition or change in the chemical character of the coal to any substantial extent.

' For example, a solution of coal may be obtained by heating, with or Without pressure, a coal such as Pittsburgh seam coal in any of the above solvents to a'temperature of around 300 C. to 350 C., depending on the given coal and its decomposition temperature. vThe insoluble matter in the raw coal, namely, the mineral charcoal or fusain, the ash and the pyrites, not considered a part of coal as such, may remain. to substantial extent-suspended in the coal solution, and if desired it maybe removed by ltration, centrifugation or in any other manner.

An object of the present invention is to provide a process whereby the coal may be easily recovered from a solution.

'Ihe process of the present invention comprises .heating a coal solution in a thin uniform layer or in the form of globules, preferably in the presence of steam. By this method, the solvent is evaporated without overheating the coal substance. The coal substance remains as a solid 40 residue and its nature is such that it can be readily removed from the surface with which it is in contact. When tar is used as the solvent, the residue contains pitch uniformly distributed throughout the coal mass.

A form of apparatus used for carrying out the present process is shown in the accompanying drawing in which the single figure is a vertical sectional view of the apparatus, partly in elevation.

The apparatus shown comprises a rotary cylindrical retort 1-, the outer surface of which is uniformlyheated. Any heating means'such as the furnace 2 may be provided.

A exible joint 3 is provided at one end of the retort so that coal solution and steam may be fed into the retort and vapors Withdrawn therefrom while the latter is in motion. The coal solution is fed through a pipe 4 and the steam is fed through a pipe 5, a, portion of which is perforated. A pipe 6 serves 'as an outlet for the vapors coming 60 from the retort.

The pipes 4, 5, and 6 are concentrically arl ranged and are positioned' axially with respect to the retort l, with the exception of the perforated portion of the steam pipe 5, which portion is preferably close to the inner surface of the retort to permit steam to impinge on the surface of the material treated. In the apparatus shown, rings 7 and 8 are provided So that the coal solution layer extends over that portion of the retort which is in direct Contact with the hot gases from the furnace. As the retort 1 revolves the coal solution is distributed over the inner surface of the'retort and the' resulting oil vapors and steam pass -out 75 through pipe 6 to a condenser 9.

After thesolventhas been removed from the coal, the now `of steam is cut off and the rota tion of the retort is stopped. A cover plate 10 at the end opposite that through which steam, coal solution and` vapors pass, is removed. The dry coal is Aloosened and raked out of the retort 1.

The applicationA of vheat and steam or other inert `carrier gases may be adjusted Yso that any product intermediate between the original coal solution and the oil-free coal substance may be obtained.

Numerous olher forms of apparatusand proc-'- esses may be suggested for carrying out the present invention. The processes may be continuous `or in batch. The retorts used may be horizontal, inclined or vertical. Coal solution may be introduced by spraying, squirting or flowing it onto the heated surface. Heating of the material may be accompanied by pressure of Vacuum. Superheated steam or other carrier gases such as carbon dioxide or flue gases may be introduced and plows or Scrapers may be used to continuously remove the heat-treated material.

Coal may be recovered from a coal solution vby spraying or atomizing l\he solution into a hot chamber. The solventis vaporized and the vapors withdrawn and recovered. A finely divided solid coal substance Settles. to the bottom of the chammaterial, such as molten metal or salts. This method can be made continuous by owing the coal solution on one end of the hot bath and mov- King it across the surface thereof. The heating of the coal solution may be regulated .so that a portion of the solvent remains in the coal. In this' case the coal preferably' while hot, may be easily compressed into any desired form.

While heating 'coal solutions to evaporatethe solvent they may be treated with air or oxygen. The eect of this treatment is to change the properties of the coal.- For instance, its coking, sticking and softening properties may be altered or practically destroyed.' l

Certain materials may be added and mixed with coal solutions before the solvent is evaporated or at any other stage. For instancel coke breeze, coal slack, anthracite culm and the like may be added. If it is desired to recover coal having special characteristics as for instance equivalent to those of activated carbon, We may treat the coal solution with aluminum chloride, zinc chloride, metal oxides and the like. Also, oxidizing materials may be added to produce a coal substance of higher softening point.

By the present process, a tough strong lump coal may be produced from slackor nes. One of the most serious economic problems in the coal industry is the disposal of slack and fines which are produced in large quantities and sold at very from the same mine.

The above process permits of After the above treatment, the coal is in ja unique condition that is quite diierent from that in which itis found in nature. It is uniform and homogeneous throughout and may be practically free from ash. 'I'he product may be used in water gas machines,v in gas producers, for coking purposes, as a fuel for domestic or industrial use, in powdered or lump form. Dierent ranks of coal may be combined in solution and recovered therefrom in homogeneous condition.

Owing to the method of manufacture, the product of the present invention is free from the laminations and cleavage planes which are characteristic of raw bituminous coals and possesses unique strength and toughness for this reason. This srength may be further increased by the addition of fillers as described above.

We claim as our invention:

A process comprising heating coal and-tar together in thin layers in the presence of steam and

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