US1508617A - Dehydrated lignite and process of producing the same - Google Patents

Description

Patented Sept. 16, 1924.

I UNITED STATES' PATENT osrics.

mom 2. scnocm'or ausm,

IDEHYDRATED LIGNITE m 230G138v OF PRODUCING m sum Drawln To all whom it concern:

Be it knownthat I, EUGENE P. scnocn a citizen of the United States, residing at' Austin, in the county of Travis andstate of lignite and a process of producing the same,

and has for its object to provide a procedure which will be comparatively inexpensive to xcarry out, and more e'flicient in practice than those heretofore proposed, while at the same time roducing a superior product. Wit these and other objects in view, the invention consists in the novel steps and combinations of steps constituting the process and in the novel dehydrated lump li r nite fuel constituting the product, all as m l be more fully hereinafter disclosed and particularly pointed out in the claims.

In order that the precise invention may be the more clearly understood, it is said:

Fresh lignite as obtained in the mines contains say from 25% to of moisture,

which it loses when heated at 110 C. to constant weight. Heated above this temperature, to 300 C. it gives up still more moisture, and some carbon dioxide; and heated still higher it be ins to yield tar, and combustible gases; t e dee -seated decomposition which it then un er oes involves an exothermic reaction so t at the heatin power of the products when used as a fue 1 is less than that of the originalmaterial and the decomposition thus entails an actual 10m of heating power.

When exposed to air, rawlignite 've s up a large fraction of its moisture an disintegrates so extensively as to become mostly dust or fine pairticles. thTllggfilggfldifitfition takes ace in e w "re a used as a'fiiel, and hence, unlasaapecial ates are provided, much of the I 'to lope unburned-int the ash pit. a.

Application fi led July 17, 1833. Serial Io. 878,058.,

heated in retorts or dryers to ex 1 the moisture, lignite disinte 'te's entirely pro ducing dust or very smal fra 'ments.

The large amount of water in lignite and the fact that it disintegrates whenever it loses its water either in storage or during combustion, naturally affects its commercial value greatly, andhence im roved processes. for making a better form oi fu'el-out of lignite have been and are being actively sought. 00 The ,only process heretofore known to me roposed, for, producing a better form or of fump fuel from lignite consists of retorting the material and briquetting the resultin powder. This requires 10% or more 66 of a class asphalt, coal tar pitch or other suitable carbonaceous hinder, a mix- .inn 0 ration to impregnate the pow er with t e binder, and then briquettin the material with strong presses. The difliculty 70 of doing this economically and the high cost of the initial'installation has retarded capitalists from entering into .this business. It results that the proper machinery, as well as the details of the wholeprocess are today still in their experimental stages.

I have discovered, on the other hand, that when fresh lump li ite is heated in a .still and immersed in thin petroleum oil, such as gas oil or engine distillate,'it gives up its moisture without forming any appreciable amount of powder or small fragments.

In fact, the original lumps remain intact, although they may have formed some cracks. Most of these cracks are very fine, while as large parts of the pieces are entirely free from cracks.-

This invention, however, 'is not limited to the use of the sgeeific Oll mentioned for oils having a are ne base as well as oils having an asp altic base of all degrees of thickness can be. used, but I prefer a thin oil to a thick one for most pm In carrying out this process, I therefore prefer to cover the lignite entirely with oil 9 and tgm use t1the lumpahaa th5y ordinarily come. m e mine w an rangeiaa in smallest dimensioii from 1 min to 5 mail es, and in largeetdimeneions from 8 to 8mcbaeTheumereqwsd m hatfl9 temperature of the mixture to 250 C. in

1 air dried lignite. Further. the fragments the still -is about two hours. At the end of fthat-time, no moisture appears to be comheating power of 19,250 B. t. u.

ing from the still. The oil is then drained 5 out of the still. An examination of. this oil-heated lignite shows that all the lumps retain their original form, and although the treated material is ibrittle, yet most of the 'piece siare sufiiciently firmto be handled .10 without disintegration. As compared with someof'the same lignite which is air-dried simultaneously, 'the oil-dried lignite shows I a much smaller'number 'of cracks, which do not gape open as wide as is the case in the formed on breaking the oil dried lignite are relatively large, whilethc air-dried material is cracked :so extensively that it separates readily ,into verv small fragments, and even intodust; particles.

In order'to improve the physical condition of the oil-heated material still further it may: be submerged in hot asphalticoil such as Mexican crude fpetroleiun.of about 12- B. and retained thcrelnat'a. temperature of 250 to 300.C. for-abouttwo'hours" The oil isthcnjdrained out of the still-while it is. lVh'en' 5 this last f-named gprocedureis we obtain the following figures y calculatio'n: Heat obtained from the 10% oil in 1 lb. of material.- Heat obtained from .the 90% lignite in 1 lb. of materiaL- 11,107 B. t. u. Heating power of 100% of this lignite without oil 12,340 B. t. 11. Per cent loss of moisture and other non-combustible volatiles from ,Original lignite required to raise its heating power from 8,640 B. t. u. to

1.925 B. t. u.

12,340 B. t. u 30.0% Per cent of remaining volatile A combustible matter in raw lignite 30.22.

It should 'be noticed that in the above operation the lignite was heated much above 110? C. and that a part of the32.07% volatile combustible matter of the raw lignite was also expelled. That is, we should take from'th'e' above 30% loss of moisture and other non-combustibles the moisture content completed, it isf found that the lu'i'npsj have of 28.15%of the rawlignite to get-thejdif- Wiretaihed so little of this thick .oil'onthe out- ,"ide asrto': leavejf them 7 practicallvj ry, al-

thoughthe materialhas beenso thoroughly -;-permeated-w ith the oil as to 'befnon-brittleg land hencef'capableof standing a gooddeal of handlingwithout'extensive breaking of the lumps. 'Ini factgit is found that,-'"at most. I

- only jthe lumps with'diameterslargerthan 3 j .to 4 inches may break up, andt'tliatfjnonei on: 4 the. fragments formed are smaller'than a 40 I following results:

pecan nut, while' mostiof thenrgangieldmsize; from ahens.eggup'ward. I prefer to use a thin oil in'the first'treatment" because a thick 'oil foams whensteamis formed in it at or near the boiling point of water, and it probably does not soak into the-cracks as readily gt a relatively low temperatureas a-thinoil oes. Upon examination, the final product progives' the following results:

I .duced by the two treatments above-described Volatile combustible mattem- 51.13% Fixed carbon 39.42% Ash I 9.45% Heating power.' 13,032 B. t. u. Moisture None.

The same "raw untreated lignite gives the fere'nce amounting to 1.85% and this differ "ence of -1.85% should be subtracted from the 32.07 in the raw lignite, thus leaving the 30.22% of remaining volatile combustible matter arrived at' before.

' The ,latter per cent of volatile combustible matter (30.22) together with that of fixed carbon (31.59) and ash (8.19) in the raw lig-' 'ni'te-will' belarger in the trc'atedlignite by the amount: corresponding to the loss of 30.0%; volatiles lost mi nus 10%- oi -oil added, or in other words. the per cents of those ingredients .will. be increased ,in the ratio of to 90, and hence become,

,Volatile combustible matter plus 10%, oil. 48.90%

Fixed carbon; 40.60% Ash 10.50%

. These figures are found to'be in. part slightly greater and in partslightly smaller vthanthose'obtained by examining the treated lignite. Hence, .we may consider'that 10% of oil is approximately the amount absorbed. .Since the material was allowed to absorb and retain all of the oil that itwould,

we may further look upon the amount of 10% to be the maximum it can take up. This is of importance in comparing the cost of this process of treatinglignite with the,

cost of another process now proposed for the conversion of lignite to an industrially suit.

able form, namely that of retorting and nite is retorted to an extent that removes all the moisture plus some combustible gas and tar, and in this operation the lignite disintegrates practically entirely into a powder or granular mass. This mass must then be mixed with a suitable binder and pressed, with powerful presses, into briquettes of various suitable shapes.

Many binders have been proposed for this purpose, but at present only two kinds seem to be suitable: (a) a thick asphaltic or pitchy residues left and obtained in the distillation of coal tar or of crude petroleum. These residues must be made up of compounds which are stiff and tough when cold, but thin when hot. (6) Starchy or syrupy residues such as are obtained in making sugar (e. g., black strap molasses), and from paper manufacturing (sulphite pitch). These binders are soluble in water and hence are less suitable than the class (a) binders.

The better class of bindersthose of class (a) must be used in a minimum amount of 10%. Even this amount will not coat every speck of the lignite powder so thoroughly as to prevent the absorption of moisture. Furthermore, the asphalt or pitch must be of high grade, that is, it must become so stifi' on cooling as to give the briquettes the proper rigidity.

These extreme and costly requirements, on the other hand, do not need to be met by the thick oil I use to impregnate the lumps of oil-heated lignite. This thick oil serves to make the mass elastic, and while it glues together some of the split-planes, yet the rigidity is maintained by inherent hardness of most of the material and not by the' binder. It is surprising that only 10% of oil is absorbed by this lump lignite, even though no attempt is made to press the cracks, etc., close together. But a probable explanation resides in the fact that none of the tar 0r oily components of the original lignite are destroyed by my oil-heating process, while any process of retorting lignite certainly destroys from 5% to 10% of these components present. My procedure, accordingly, takes advantage of this important fact.

In order to reduce the volatility or flashing of my product to a minimum I remove the lighter oils from the thick oil by bubbling steam through it while the lignite is heated with it. The resulting oil will naturally glue up the cracks somewhat firmer than a thinner oil, yet this is not essential to make the material retain its shape while it is handled. The steaming out of the light oil is done only to remov'esome of the most volatile oil.

From the foregoing, it will now be clear that my process provides a procedure which is comparatively inexpensive and simple to carry out, while it also produces fuel lignite of a high calorific value in its natural lump form capable of being handled without briquetting. Further, it is found that this oil treated dehydrated lump lignite is not materially affected by re eated wetting and drying in the hot sun. It does not soften in the flame and the lumps do not crack to an objectionable extent while burning, but retain their form until burned to ash. In other words, the finished product simulates the behavior of bituminous coal on burning, except it does not melt and fuse together.

An important feature of the invention resides in the fact that it requires only relatively cheap oils which are plentiful instead of equal amounts of the expensive asphalts now used in briquetting. The bearing of this upon our large undeveloped lignite deposits needs no comment.

The finished product is preferably produced in the lump form above mentioned but of course it could be as readily produced in a finer or a coarser form, or it could be used as a raw material like finely divided coal for making bri uettes, or it could even be mixed with coal. en in the lump form after treatment with a thin oil it has a toughness comparable with charcoal and dark smooth surfaces. After the treatment with a heavy crude oil the toughness is increased and the lumps take on the dark shiny appearance of soft coal. In both cases the product can be readily distinguished from the raw li ite both by its physical appearance and its toughness.

It is obvious that those skilled in the art may vary the'details of the procedure. as well as the form of the'finished product without departing from the spirit of the invention, and therefore I do not wish to be limited to the above disclosure except as may be required by the claims.

What is claimed is:

1. The process of treating lignite which comprises heating the same in contact with a hydrocarbon oil to drive off the moisture present, and removing the oil not absorbed by the material, substantially as described.

2. The process of treating lignite which comprises coating the same with a hydrocarbon oil; heating the coated lignite to a temperature suflicient to drive off a substantial portion of the moisture present; and removing any oil not absorbed by the lignite, substantially as described.

3. The process of treating lignite which comprises coating the same in the form of lumps with a hydrocarbon oil; heating the coated lignite to a temperature sufiicient to drive 011' a substantial rtion of the moisture present but ins cient to destroy its lump like form; and removing any oil not absorbed by the lignite, substantially as described.

4. The process of treating lignite which 5 consists in coating lumps of the raw material with a hydrocarbon oil; heating the coated lumps to a temperature sufiicient to dehydrate the same; draining off any oil not absorbed by said lumps; again heating said lignite with a hydrocarbon oil; and re- 10 moving the surplus oil, substantially as described.

In testimony whereof I aflix my signature.

EUGENE P. SCHOCH.