US1012676A - Briquet. - Google Patents

Description

' No Drawing.

erto unavailable small sizes such as UNITED STATES PATENT orrron.

CHARLES T. MALCOLMSON, OF CHICAGO, ILLINOIS.

BRIQUET.

To all whom it may concern: I

Be it known that I, CHARLES T. MALCOLM- SON, a citizen of the United States, residing at Chicago, Illinois, have invented a certain.

new and useful Improvement in Briquets, of which the following is a full, clear, and exact description, such as will enable others skilled in the art to which it appertains to make and use thesam'e.

This invention relates to a new and useful improvement-in themanufacture of briquets, the object being to produce a briquet having a dense compact body with a minimum amount of pitch or like binder.

Immense quantities of fine anthracite coal dust (culm) obtained in th'e'preparation of sized anthracite coal for market, are piled as refuse near the mines. Usually this culm contains too much deleterious ornoncombustible matter to. warrant its use commercially, so that when these culm banks are worked over to obtain the larger sizes contained in them, the coal is washed or jigged to remove part of the impurities. The same process is used in the preparation of commercial sizes of-anthracite at many 0 the mines to-day, making salable the batharley, rice,-etc. These smaller sizes are not suited to domestic-use, but are sold for steam purposes in the eastern cities, 01' burned on the locomotives of the anthracite carrying railroads, usually mixed with other coals. i

In the middle and far west large lignite bearing areas exist. The better grade of this-fuel is mined and sold for domestic and heating purposes, when higher grade coals are not available or are sold at such a high price that the lignitescan besold in competition and bring a reasonable-profit to the producer. These lignitic .coals produce considerable slack in mining, which on account of its low fuel value and the fact that it deteriorates rapidly when stored, is practically a waste product.

There are certain bituminous coals distributed throughout the country which will not produce coke. The slack from these coals has no value except for steam purposes. There are processes developed in Europe by means of which dry coals, lignite and peat can be utilized in making gas and the resulting by-prod'ucts find a ready market. But 1n the United States the low price of fuels and excessive cost of Specification of Letters Patent.

'coal.

PatentedDec. 26, 1911.

Application filed January 10, 1910. Serial No. 537,168.

these plants has restricted their use. Briqueting plants are being established in this country for the utilization of these low grade or hitherto waste fuels. By this'process the fine coal, culm or slack is mixed with a bonding material and compressed into briquets of various shapes and weighing from 2 ounces to 20 pounds. Briqueted coal produces results equal to or greater than lump coal from the same mine.

In general practice hard pitch made from coal or water} gas tar is the binder used in briqueting coal. The percentage of pitch required to make satisfactory commercial briquets varies with the size of briquet, character of the coal and. process used. In making briquets from anthracite coal from 10 to 13 per cent. of pitch is used: briquets made from coking bituminous coal require from 6 to 8 per cent, while in the briqueting of non-coking and semi-anthracite coals from 8 to 10 per cent. of hard pitch binder f the percentage be reduced to a minimum.

Pitch is composed largely of volatile hydrocarbons or the smoke producing "elements of Thus it is desirable to add as little pitch as possible in briqueting bituminous coals already high in volatile matter: In the treatment of anthracite and lean coals this feature is not objectionable.

Anthracite, the non-coking bituminous coals, sub-bituminous coals and lignites have no coking or caking property: that is, briquets made from these coals will disintegrate rapidly during combustion unless the bonding material, with which they are made, does not burn away faster than the coal in the briquet or remains unaffected at the temperatures necessary to the combustion of the coal. -Pitch forms of itself a coke durin combustion which is practically pure car on and therefore burns at approximately the same rate as the fixed carbon of the coal; but the coke thusobtained is less than one-half the mass of the original pitch and is a much inferior bonding agent.

By the addition, under pressure, of the necessary hydrocarbons contained in coal tar pitch, certain non-coking coals can be made bituminous coals,

in excess of that required to manufacture good briquets, in order that the coke formed during combustion will serve to hold the slower burning coal together until consumed.

An excessive amount of pitch is required to make briquets from raw lignite and subfor reasons explained below. It is also difficult to maintain the integrity of thebriquets during combustion owing to the. excessive moisture contained in the coal which causes rapid sparking as the imprisoned water is transformed into steam. r

The percentage of pitch required to make a perfect bond depends on the amount'of surface to be coated and the density of the coal.

V I tance. It has been shown that the percentage of voids for grains of uniform size is indeshape.

pendent of the size of the grain, and is at its maximum, about 43 per cent., 'when the grains are uniform in size but irregular in It is easily shown that pulverized coal which will just pass through a screen with 20 meshes to the inch has 6.35 times the surface to be coated as that presented by anequal weight of coal passed through a screen with 4 meshes to the inch. 1

Exhaustive experiments have shown that the cohesion or strength of the briquet begins with 4 per cent. of pitch and increases until 9 per cent. of binder is used, after which the cohesion of the briquet decreases until with 28 per cent. of binder the briquet equals that of the pitch. Well made briquets have a greater cohesion than the coal or pitch from which they are made. Y

Washing anthracite, in the preparation of small sizes, not only reduces the foreign substance or ash, but also takes away the very fine dust, leaving the small coal uniform in size and free from fines.

A briquet must be dense in order to reduce breakage in handling, to prevent the absorption of moisture (hygroscopic) and prevent excessive'smoke during combustion. A dense briquet is obtained byl filling the voids and manufacturing under igh pressure. Either one of these factors may be varied at the expense of the other. In the fabrication of small briquets the relatively large surface with relation to the volume makes possible a high total pressure on the surface of the briquet. Butas the volume increases, in order to maintain a constant ratio of mass and house heating furnaces, locomotives or wher-.:

ever it isdesirable to maintain a deep fuel bed.

It is essential that thebinder be distributed uniformly through the coal in order that each particle shall become effective. In

practice it is necessary to add sufiicient binder so that the minimum amount contained in any unit mass shall be equal to that necessary to make good briquets. This means that if the binder is not thoroughly mixed with the coal an excess of binder is necessary.

The difiiculties attendant on making a perfect mixture of coal and binder in a commercial plant increase wit-h a decrease in the percentage of binder used. Thus it is much easier to mix 25 per cent. of binder and 7 5 per cent. of coal than 6 per cent. binder and 94 per cent. coal. The finer the binder is divided the easier it is to distribute'it uniformly throughout the mass of coal.v

We will consider here only the use of hard dry pitch as a binder and not the process by which the pitch is melted independently and introduced into the coal as aliquid. Even very hard pitch is difficult to grind or pulve'rize by mechanical means, and if the reduction is very fine, it is practically impossible to convey, store or measure it mechanically. The powdered pitch sticks to the machinery, and tends to return to a solid mass if allowed to stand or if subjected to pressure or rubbing surfaces. The addition of coal to the pitch entirely eliminates these difiiculties.

In the treatment of anthracite small sizes with which we are particularly concerned,

it is diflicult and therefore expensive to reduce to fines the already minute and uniform rains of barley or rice by the use o mills or pulverizers available in the market today. The hammer type of crushers in general use depend upon the impact of a blow to break up the coal, and their effectiveness decreases rapidly with these small sizes.

In the formation of briquets according to my invention, I utilize fine hard anthracite particles of available sizes and fill the voids with a mixture of bituminous coking coal and pitch.

In the briqueting of anthracite coal in practice, I determine first the percentage of voids which we will assume to be 25 per cent. of the total volume of the coal. I then prepare the mixture of bituminous coking coal and pitch in the right proportion, say 25 per cent. of pitch and 75 percent. coking coal, having a total volume equal to the voids in the coal to be briqueted. This mixture of cokin coal and pitch which we will call the binder is pulverized very I fine and then thoroughly mixed with the can be easily coal. The mass is heated with the proper admixture of moisture to a temperature which will thoroughlyliquefy the pitch after which it is cooled to a temperature at which the agglomerate can be successfully briqueted, passed through a briqueting press and molded into masses of definite size and shape. By this means I utilize a coal which will not detract, in any way, from the quality of the anthracite briquets, but one which reduced to the proper size to furnish the necessary fines t-o fill the voids, thus making the densest possible briquet under minimum pressure and with the minimum requirement of pitch. The addition of the coking coal not only reduces the percentage of binder necessary to make mechanically perfect briquets, but, serves to hold the briquets together in the fire, and supply the volatile hydrocarbons essential to a high grade steam coal. The briquets will burn entirely from the sur face, be retained as a compact mass after the volatile hydrocarbons of the pitch are driven oil, and not disi ,tegrate in the fire until entirely consumed.

In the case of coking and non-coking bituminous "coals and sub-bituminous coals and llgn tes, my process serves to reduce the percentage of binder by a more even dis-- tribution ofthe pitch and a means of main,-

taining' the-proper percentage of fines to keep the voids at a minimum. With these coals my invention contemplates the use of nous coking coal 'minous coking coal particles,

particles of coal not to exceed 9; inch in diameter, in combination with smaller sizes in the proper proportion to reduce to a minimum, the percentage of voids, and'the total surface contained inthe briquet. With lignites I am able to produce briquets which overcome largely the difliculties encountered in the use of raw lignite. I The briquetswill burn similarly to those made from bituminous coal, maintaining a coherent mass untilentirely consumed." They will not be hygroscopic nor the weather. -/The' characteristic sparking will be retarded if not entirely eliminated, and the objectionable sparks or cin'ders greatly reduced.

I claim:

- 1. Abriquet composed essentially of hard anthracite particles, whose voids are filled with a composition of pulverized bitumiand pitch mixed to serve as abinder.

'2. A briquet composed of anthracite coal particles, pulverized pitch mixed with bituheated until the pitch being liquefies, and

then cooled to a proper-temperature for;

molding in a press.

3. A briquet composed ofanthracite coal particles and a binder comprising pulversaid mixture disintegrate when exposed to' ized pitch mixed with bituminous coal particles, the mixture of anthracite coal and binder being heated until the pitch 1i uefies.

In testimony whereof I hereunto a x my si ature in the presence of two witnesses, this 8th day of January, 1910.

CHARLES T. MALGOLMSONL' Witnesses:

F. R. CORNWALL,

M. P. SMITH.