US1703192A - Art of treating shale and other bituminiferous solids - Google Patents

Description

W. H` HAMPTON ART-OF TREATING SHALE AND OTHER BITUMINIFEROUS SOLIDS Feb. 26, 1929.

'i0 complex combination.

, sometimes also with Ilvatcnted Feb. k26, 1929 UNITEDI STATES PATENT oFFl WILLIAM HUNTLEY HAMPTON, 0F PORTLAND, O BEGON.

I ABT 0.1!'A TREATIG SHALE AND OTHER BITUMINIFEBOUS SOLIDS.

, Application led December 30, 1921, Serial No. 525,896. Renewed .Tune.2 8, 1928.

This invention relates to `art of treating ,shale and other bituminiferous solids; and in particular the invention has -to do'with the digestion of-shalel lorthe like with a heavy mineral oil, in intimate mixture with a relatively `small' proportion of an added ammonia-liberating base, such as caustic lime, under conditions of temperature such that complex ni- 'trogen compounds present in the bituminiferous mineral are decomposed at least .to a substantial extent with liberation of ammonia which can be recovered by suitable means concomitantly with recovery of valpable hydrocarbon oil fractions vaporized during the digestion process,I while at the same time sulfur present in reactive condition is bound or fixed and its evolution as hydrogen sulfid and analogous undesirable volatile sulfur compounds is substantially suppressed. v

In prior copending applications Ser. No.' 318,833, Ifiled August 20, 1919, Ser. No. 344,016, filed December 11, 1919, Ser. No. 345,485, filed December 17, 1919, Ser. No. 431,188, filed December 16, 1920, I have disclosedand claimed methods of treating shale and other bituminiferous solids by digesting the same in finely divided condition and in fini d admixture with a relatively heavy mineral oil at temperatures preferably ranging from about 600 to 700 F., and recovering hydrocarbon oil fractions vaporized during the digestion, the residual solid mineral matter remaining after the digestion being lthen most desirably separated from the accompanying unvaporized oil and bitumens and subjected to destructive distillation for recovery of hydrocarbon products from such bituminiferous matter as mayhave resisted the liquefyng and resolving act-ion of the digestion oil. The process thus briefly outlined has proved thoroughly successful but in carrying the same out in .practice I have now found it especially advantageous to introduce cer-l tain modifications that achieve and increase the eiciency and economy of the process and otherwise favorably affect the results at-4 tained. The bitumens present in oil shale and like mineral matter tain appreciable percentages of nitrogen in Sulfur may also be present either in organic or inorganic combination, or both. The Y combination with hydrogen and carbon, and sulfur, in the form of amido or amido-sulfur compounds.

Under the conditions of digesting shale practically always con.

nitrogen exists partly inv with oil in accordance Withthe procedures disclosed in my prior applications aforesaid, practically none of the nitrogen existing in these complex forms is liberated as ammonia durin digestion. The oil fractions vaporized uring digestion and recovered as condensates, as well as the residual unvaporized body of oil comprised in the digested mixture, contain nitrogen compounds; andso does the residual solid bituminous matter that has resisted or escaped t-he breaking-down action of the hot oil present in the various oil fractions cause the oils to darken upon' standing. and to deposit but soluble in certain solvents such as alcohol .or benzol. The aforesaid residual solid bath. The nitrogen compoundsy bituminous matter, upon separation from the v i The sulfur content of the original shale or other bitumini-ferous mineral treated may be present asa constituent of or associated with bitumen complexes, in which form it is highly detrimental because itis largely reactive at the digestion temperatures in question and is evolved as hydrogen sulfid or analogous volatile sulfur compounds when digested at 670o to 700 F. under the conditions of operation set forth in my prior applications aforesaid. On the other hand, sulfur present in the form of iron pyrites, which are carried by some shales, is not evolved during digestion, iron pyrites being substantially inert at' the temperaturesof digestion. Similarl stable compounds such as sulfates are not a` ected.

It istherefore a principal object of the present invention to so conduct thel digestion treatment of the shale or other bituminous mineral as largely to break down the nitrogen complexes present and to liberate ammonia which can be recovered as a valuable by-product separately from the oil fractions vaporized during ing formation and deposition of resinous substances of the character above mentioned not only in the lighter oil fractions but also in those not vaporized during digestion. Afurther object is to bind or fix reactive sulfur in such manner hydrogen sulfid or inl other volatile form while at the same time purifying the hydrocarbon oils produced by the process.

igestion, at the same time avoidi as to suppress its liberation as Other objects and advantages of the inven-l I' 70 resinous asphaltic substances lnsoluble in oils tion will become apparent as 'the 'description proceeds. t

The accompanying drawing shows diagrammatically one system of apparatus for carrying out the novel process.

I have found that the objects of the invention are attained by carrying ont the digestion treatment in the presence of a suitable proportion of a base that will react under the conditions l.of digestion to liberate nitrogen as ammonia, either wholly or to a substantial extent, from the combinations in which it occurs in the mineral; and that will also react to bind Areactive sulfur present. Any base capable of reacting to attain these results, can be utilized Within the broad scope of the present invention; but for practical purposes it is found advantageous to employ lime as the basic reagent in question, and especially to employ caustic lime (CaO), the hydrated form being usually much less effective. The exact quantity of lime or other basic reagent to be employed in a given instance naturally depends upon the proportions of nitrogen and sulfur contained in the shale in a form which they will react with such base. With the ayerage shale, an addition of 1 to 2 per cent by Weight of caustic lime is ordinarily suliicient to accomplish the purposes in view; and it is a very exceptional shale that requires as much as 5 per cent to achieve the results sought.

In order to secure the best results in carrying out the invention, it is of great importance to ensure that the caustic lime or other basic reagent is brought into proper reacting relation with the shale. For maximum effectiveness, both the shale and the lime should be finely pulverized and very intimately 'commingled. This is best accomplished by grinding the lime and shale together, the' shale having been previously. dried if necessary so that the lime undergoes little or-no hydration during the mixing or blending operation. In a particularly desirable Way of accomplishing this grinding in practice, the shale which has been previously coarsely comminuted by rough crushing, is delivered, together with the necessary amount of added caustic lime, from the bin 1 into the agitating means shown at 4. .The heavy oil to vbe usedr in the digestion mixture is supplied from the tank 2. The mixture is stirredand preheated to say 300 or 400 F., at which temperatures the shale becomes comparatively soft fand fr iable and is thus in particularly favorable condition to undergo line grindingin suitable grinding machinery, whereas without Such prt/heating' it-isvery much more dicult to pulverize. 'IIhe mixture thus prepared and preheated as described may be run into a ball mill or other suitable grinding device 5 and the solid constituents of the mixture reduced with comparative ease to a in'e'-" ness such that substantially all of the Solids will pass a 1D0-mesh screen, and in practice it is found desirable that the grinding or pulverizing be continued until 60% or more of t-he solids will pass 20G-mesh.' This treatmentachieves a most intimate commixture of the ca istic lime with the bituminous mineral, thereby favoringefticient reaction of the lime upon the decomposable nitrogen compounds of the mineral during the subsequent kdigestion with liberation of ammonia on the one hand, and binding of reactive sulfur as cal. cium sulfid (CaS) on the other. Furthermore, fine grinding effectively exposes the refractory bitumens of the shale tothe liquefying and decomposing action of the heavy digestion oil.

.The oil used for the digestion bath may vary considerably in character but it should desirably consist Wholly or in substantial part of oil fractions that 'do not vaporize extensively at or below' 700 F. In starting operations, this oil may be a stripped oil, a grade of steam cylinder stock known commercially as Congo cylinder oil being suitable, for example. After the process has'been operating for a sufficient period,-the digestion oil used may be the heavier fractions of oil de-` rived from the shale itself, said oil being supplied through pipe 28 and tank 3. vIn some cases it is advantageous to employ crude petroleum for making up the digestion bath. The amount of heavy oil so commingled with the shale and lime may vary considerably 'depending upon the character of the particular shale to be treated. In the case of a typical Colorado shale that normally yields about 30 gallons of oil .per ton by the ordinary Scotch distillation method, mixing about one volume of heavy oil with two volumes of crushed shale gives good results.

4Richer vshales require relatively less heavy oil, and leaner shales more. The quantity of caustic lime used is advantageously somev Whatin excess of that theoretically required to effect the desired ammonia liberation and sulfur fixation, especially since the breaking down of some ofthe oxygenated vbitumens during the digestion apparentlyeiects hy.- dration of the lime to some extent and thus reduces its activity at this stage ofthe process, although this hydration is of advantage, at a later stage, as will hereinafter vbe pointed out.

As a rule, the use of t-Wo lper cent by Weight p of caustic lime, figured on the weight Aof the Y shale. 1s sufficient, yand in many' cases onevper 1" 'cent 1s enough.

"Ihe linely ground, mixture prepared as above described andy of slurry-like consistency, is led through' pipe 6 `intofthe digestor means shown at 7 and 8. 4The temperature 1f of digestion should be high enough to bringI about 'the desired liquefaction and breaking down of the shalebitumens in the oil digestion bath.` At the same time the temperature should not be allowed to go high enough A of from 600o to 700o F. being suitable, and the optimum range being about 680 to 700 F. The Huid mass should also be thoroughly agitated continuously throughout the digestion to cause constant rubbing of the mineral particles upon each other and thus expose fresh surfaces to the hot oil bath. It

may be noted here that the action of the hot oil bath on the shale bitumens is not merely a liquefying or solvent action, 'but involves a chemical breaking down and decomposition of said bitumens into lighter products.- The hea oil added to the shale in making up the dlgestion mixture is also Y in its turn broken down to yield lighter products, due apparently to chemical interaction between said oil and the shalebitumens under the conditions of digestion. c'

During the digestion, ammonia is liberated and is conducted with the oil vapors and the steam generated in the reaction, through vapor oltakes 9 into vapor line 10. No sulfuretted hydrogen is evolved the reactive sulfur being bound by the lime. The oil vapors may be fractionally condensed as shown at 16 to produce commercialdistillates and the ammonia scrubbed out at 17 or otherwise recovered 'according to known methods. The unvaporized portion of the digestion mixture is treated, as by centrifuging at 11, 12 and 13, or by dilution with a lighter oil and sedimentation, to separate residual solid matter or tailings, the oil separated from such tailings being amenable to treatment lfor production of valuablelubricating oils, for example. When treating the unvaporized portion of the ldigestion mixture by the centrifugin process just mentioned the continuous ow of wash oils is supplied to the successive centrifuging units hmeans of the tanks 419, 20, 21 and 24, toget er with the circulating pumps and flow pipes. In this manner, the heavy oils and other bitumens adhering to the tailings discharged from the separators are completely washed out. The

wash oil from the first unit 11'is returned-to the digestor 7; that from the third unit 13 is returned through'19 tothe tank 20; while that from the-second unit 12 passes through 24 and is separated into its light and heavy constituents by circulating through retort 23, towers 25 and 26, 4the respective fractions lbeing returned to the tanks 21 and 3. The

oils, both heavy and light, obtainedas described, have much less tendency to darken in color, and remain much clearer than when lime is not added to the mixture. Moreover `they do not 'deposit resinous matter upon standing.

If it is desired to subject the vapors leaving the retort system 7, 8, to further cracking 'to obtain a high yield of gasoline products, the valves 29 are closed and valve 30 opened and the vapors are delivered through vapor line 14 to suitable superheating coils as described in my previous application, Serial No. 431,188. The ammonia may similarly be recovered in such a system by the usual scrubbing means. i

It should be noted that carbonates of lime and magnesia, which are often carried by shales, do not function usefully in the pressought.

The digestion can be carried on in any suitable digestor as at 7 and 8 equipped vwith stirring means 15 and 15, and provided with vapor ol'takes 9 leading to a-condenser system 16 and 17. The stirring means may adent process and-do not produce the results vantageously serve to advancethe fluid digestion mixture in a systematic manner from a point of feed to a point of discharge. Ap-

paratus of this general type being known in the art, rio detailed description-thereof v is necessary here. The residual solids or tailings from the digestion having been washed successively with a light oil in the centrifugal separators =and dried, while passing by means of screw con- `veyors through the drier 22, may be destructively distilled inretort 23 to obtain further hydrocarbon oils from such bituminous matter therein as resisted or escaped the action of the hot oil bath, and also to obtain more ammon'iafJlhe character of the tailings is such that this can be effected at temperatures ranging from 700 F. initial to 900 Fgnal, the final temperature beingobviously much lower than is ,required in the Scotch process. a This is because the prior digestion has rendered the residual bitumens lessrefractory and more amendable to heat treatment. As

regards the ready liberation of ammonia, the partially hydrated'lime serves to supply the.

steam needed at the highertemperatures of destructive distillation to and in theammollt) nia-forming reactions. It isto be noted in this connection that as a 'result of the prior digestion the lime is present in peculiarly intimate commixture with the residual solids and can thus react most effectively. The distillation is carried to coke, the. hydrocarbons driven .oi being condensed in-towerl `18 and the ammonia recovered in the scrubber. 17.

The total yield of oils vfrom shale treated bythe method hereinaboveS described is far greater than by the ordinary Scotch destructive `distillation of raw shale, and the amlmonia recovery is also larger and is obtained 'at much lower temperatures.r

y The invention has beendescribe'd more particularly with reference t0 treatment '0i bituminous shale, vfor the sake of a concrete volvedfand also because the invention at present finds its most important practicalI application in that field. Moreover, the treatment of shale is a problem distinct'from the treatment of other bituminiferous solids oW- ing to the peculiarly refractory and resistant character of the bitumens contained in shale .which has baffled many attempts to extract tively distilled to coke, the process yielding valuable hydrocarbon oil fractions, ammonia and coke by the rational and relatively low-temperature treatment set forth.

i In the treatment of shale and peat,`where the coky residue from destructive .distillation ofthe tailings is usually of too lowr calorific value for direct use as fuel, there may be a third stage in the ammonia recovery, as follows: The fixed car` bon of the aforesaid coky residue, and whatever carbon compounds have survived the Vfinal heating to 900 F., are in highly active condition at the close of the vdistillation and will take fire readily if exposed to air.. By admitting such air through inlets or tuyres 24 into contact with the coky residue in regulated quantity in retort 25, partial combustion may be effected whereby the temperature is considerably 'raised and further ammonia liberated and recovered. By proper control of the air admission, a type of producer gas can also be obtained.

lVhat I claim is:

l. In the treatment of solid bituminiferous mineral matter to obtain valuable products therefrom, the process which comprises heating| such bituminiferous matter in intimate fluid commixture with an ammonia-liberating base and a mineral oil at temperatures not substantially exceeding about 700 F., and recovering volatilized products. v

2.v In the treatment of solid bituminiferous mineral matter to obtain valuable products therefrom, the process which comprises digesting, at temperatures not substantially exceeding about 700-F., such bituminiferous matter in finely divided condition and in intimate-Huid commixture with finely divided caustic lime anda mineral oil, and recovering volatilized products.

3. In the treatment of solid bituminiferous mineral matter to obtain valuable products therefrom, the process which comprises heating such bituminiferous matter in intimatefluid commixture With an ammonia liberating base and a mineral oil at temperatures not substantially exceeding about 700 F., the

"mixture being agitated kand maintained fluid throughout the digestion, recovering velatilizcd products during digestlompseparatmg residual solid mattei' from the still fluid mixture after digestion, and distilling such separated'solid matter to distillate. f 4. 'Ihe process as defined in claim 3 further characterized 'by conducting the coking distillation at temperatures from about 700 F. up to about 900 F.

5; The process as defined in claim 3 further characterized by subjecting the resultant coke, without cooling, to controlled'combustion', and recovering ammonia from the comh bus'tion gases. condition With lime and a heavy oil, dlgested `as before described, and the tailings destruc- 6. The process of treating solid bituminiferous mineral matter to obtain valuable products therefrom, which comprises digesting an intimate commixture of such bituminiferous matter and an ammonia liberating b..se, both in finely divided condition, in a mineral oil bath,at temperatures above 500 F. but not vsubstantially exceeding 7 00 F., and recovering volatilized products. erous mineral matter to obtain valuable products therefrom, which comprises digesting an intimate fluid commixture of finely divided fbitmniniferous matter anda finely divided ammonia liberating base with a heavy mineral oil, at temperatures Within the approxi- -mate range of from 600 to 700 F., to liberate ammoniafandv volatilize certain hydrocarbon oil fractions.

8. The process of treat-ing solid bituminiferous mineral matter to obtain valuable products therefrom, which comprises digesting a finely ground mixture of such bituminiferous matter and not exceeding about 5 per cent of its Weight of caustic lime with a heavy mineral oil a't temperatures approximating 680 to 7 00 F., to liberate ammonia and volatilize certain' hydrocarbon oil fractions.

9. The process of treating solid bituminiferous matter of the shale type, to obtain valuable products therefrom, which comprises digesting an intimate mixture of such bitumin-iferous matter and an ammonia'liberating base with a mineral oil at temperatures sufficiently high to liberate ammonia but insufiiciently high to cause substantial deposition of carbon, and also recovering valuable hydrocarbons from said mixture.

10. The process of treating solid bituminiferous matter of the shale type, to obtain val- The process of treating solid bituminif-v coke With recovery of v rial at temperatures Withinihe approximate 'l range of from 600 to 700 F. with sufficient heavy mineral oil to provide a. fluid digestion mixture, and recovering both liberated ammonia and volatilized hydrocarbons.

Y11. The process of treating bituminous shale or the like to obtain valuable products therefrom, which comprises preparing a mlxture of pulverized shale or the like with caustic lime and enough heavy mineral oil to ive the mixture a, fluid consistency, d igesting said mixture with the aid of agitation at temperatures sufficiently high to liquefy a substantial portion of the shale bitumens but insufficiently high to cause substantial carbon deposition, said mixture remaining fluid during the digestion, recovering ammonia liberated and hydrocarbons volatilized during digestion, separating residual solid matter from the digestion mixture, and destructively distilling such separated solid matter.

12. The process of vtreating bituminous shale or the like which comprises heating and agitating a fluid mixture of inely ground shale, finely ground caustic lime and a heavy mineral oil, at temperatures above 500 F. but not substantially exceeding 700 F., and recovering liberated ammonia and volatilized hydrocarbons.

13. The process as dened in claim 12 in which approximately l to 2 per cent of lime is employedin the mixture.

14.-. The process as defined in claim 12 characterized by the further steps of destructivel; dist-illing the residual solid matter from t e digestion to obtain coke and further volatile matter including ammonia.

l5. The process of treating solid bituminilerous mineral matter which comprises digesting such matter in finely divided condition, at temperatures above 500 F. but insuliiciently high to eect substantial cracking, in admixture with mineral oil and a basic reagent capable of binding sulfur present in reactive state under the conditions of operation, and collecting a distillate.

16. The process of treating bituminous shale or the like which comprises digesting, at temperatures above 500 F. but not substantially higher than 700 F., a fluid mixture comprising inely divided shale, a heavy mineral oil, andv a relatively small proportion of caustic lime, and collecting distillate from the digestion.

In testimony whereof I hereunto alix my s1gnature.

WILLIAM HUNTLEY HAMPTON.

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