Oil-shales of the United States and methods of testing

Acquaintanceship with the oil-shales of the United States is only just "being formed". Their possibilities as future producers of a substitute for petroleum will depend obviously on future demands for the products that can be synthetically made from the very complex organic material of the oil-shales. It is necessary that products from shale oil be made which closely resemble petroleum products as regards their commercial usefulness. There may be other uses, however, for shale oil products. The subject of oil-shales is of wide interest and much is published by able contributors on the economic, commercial, and technical problems, yet there can be little doubt that the solution of the chemical problems is only just begun.

OIL-SHALE OF THE UNITED STATES AND METHODS OF TESTING LEWIS C, ICARK1CK l i l B i i B M Digital Image © 2006 LEWIS C. KARRICK. All rights reserved. OIL - SHAIES OF THE UNITED STATES and METHODS OP TESTING By Lewis C* Karrick. Presented in Partial i?\ilfillraent of the Bequirementa for the Degree of Mining Engineer. Approved byj- - - T i .V .'■a - mi Digital Image © 2006 LEWIS C. KARRICK. All rights reserved. IHDBX Page Value of an Oil-Shale Difficult to Determine........................................ 2 Shale-Oils are Variable..................................................................... 5 Oil Yield is Indefinite ............................................................................. 6 Quantity vs. Quality................................................................................ 6 e Origin of Shale-Oil......................................................................................... 9 Non-Gracked Shale-Oils Impossible .............................................................12 Comparison of Oil-Shales Impossible without Standard Hetort*. ••••••• 12 A Retort for Testing Oil-Shales ............................................................... 16 Care of Retort Important...................................................................... 16 Heat Control................................................................................................ 16 Finely Ground Shale Required for Best Operation .................................. 19 Operation of the Retort .............................................................................. 23 Determination of Yield and Precautions .................................................. 26 Volumetric Method of Determining Yield.............................................. 26 Gravimetric Method of Determining Yield................................... 27 Factors Facilitating Calculations ........................................................... 31 Use of Steam in Retorting................................................................. 32 A Rotary Retort May Give Valuable Data................................................. 33 Oils Produced Must Be Classified......................................................• 35 Testing Small Amounts of Oil................................................................. 37 Condensation and Recovery of Scrubber Naphtha...................................... 36 Nitrogen Content of Shales Important ...................................................... 40 Variation in 0il-£hale8 ........................................................................ 41 23195? Digital Image © 2006 LEWIS C. KARRICK. All rights reserved.INaSX TO FIGURES* Page I Percentage Relations of the Products of Distillation of an Oil-Shale.......................................................... 11 II Curves Showing Influence of Rate of Distillation of Oil-Shale on the Properties of the Oil Produced •••• 15 III Oil-Shale Assay Retort............................................................. 17 Digital Image © 2006 LEWIS C. KARRICK. All rights reserved. OIL-SHALES OF THE UNITED STATES and METHODS OF TESTING. By Lewis C* Karrick, Associate Oil-Shale Technologist* Acquaintanceship with the oil-ehales of the United States is only just toeing formed. Their possibilities as future producers of a substitute for petroleum will depend obviously on future demands for the products that can be synthetically made from the very complex organic material of the oiL-shales. It is necessary that products from shale oil be made which closely resemble petroleum products as regards their conmercial usefulness* dbere may be other uses, however, for shale oil products. The subject of oil-shales is of wide interest and much is published by able contributors on the economic, commercial, and technical problems, yet there can be little doubt that the solution of the chemical problems is only just begun* The dearth of this Digital Image © 2006 LEWIS C. KARRICK. All rights reserved. olaas of information causes little wonder among those who have studied the subject from a scientific angle, for as yet there has been obtained little positive knowledge of the chemical or physical nature of the oil-producing material that is disseminated through the lean shales and forms the greater part of the rich oil- shales* Neither do we have much data on the behavior of this organic substance in the many types of shales when subjected to different conditions of destructive distillation* Value of an Oil-Shale Difficult to Determine* A scientific investigation of oil-shale deposits will have very little commercial Interest unless reasonably definite conclusions can be reached as to the quantity and value of the petroleum substitutes that can be produced from the shale* At present there are a number of serious obstacles to be surmounted before such a conclusive analysis can be arrived at* tfe must aPPty* however, the technical information gained so far in guiding us toward the most valuable and logical conclusions* If one were to start out to determine the metal values of a certain complex 0 Digital Image © 2006 LEWIS C. KARRICK. All rights reserved. ore deposit, the necessary steps of his procedure would be quite definite, since they have been established and proven to be scientific and accurate* The survey is made and the samples taken within the predetermined limits by methods whose accuracy is commensurate with the value of the ore in 9 question* Next the sample is crushed, mixed and quartered, while observing the necessary precautions to avoid "salting", and is then sent to the assayer who easily performs the retired chemical determination of the metals. There is no difficulty,- the metals react with the reagents and the separation of the required values is obtained* Should further metallurgical data be required, the microscopist is called in, and he readily identi­fies the constituent minerals, since each has its characterisito crystallographic properties* Now if one were to attempt to determine the value of a certain oil-shale deposit, on the basis of its possible yield of oil, he would proceed as before in the preparation of the saiqple* 3 Digital Image © 2006 LEWIS C. KARRICK. All rights reserved. He might use a core drill for staple taking on a new deposit to make sure that the sample is representative and free from weathering* % His next step will he the actual determination of the oil-yielding capacity of the shale* with such minor additional analyses for nitrogen, sulphur and mineral matter as might he considered of value* The method, however, of amking the determination for oil yield will probably be subject to considerable criticism as being inaccurate and unscientific, and justly so, for there can be no proven successful method for this determination until it has stood the test of tir.e in its application along with commercial retorting operations, and has thereby shown itself capable of operation so as to give results that have a definite relation to the yield of a recognized successful commercial retort when treating the same shale* This is impossible at the present time, since there are, as yet, no successfully operating commercial retorts in America with which comparison could be made* There is a great possibility that the Scotch retort with modifications will operate successfully on American oil-shales, but there is no good argument for making the Digital Image © 2006 LEWIS C. KARRICK. All rights reserved. Scotch laboratory assay retort our standard for testing American oil-shalest even though it gives results that are definitely related to the yield of the Scotch commercial retort when both are operated on Scotch shales. American oil-shales differ greatly and it is probable that more than one type of commercial retort will be em- i ployed to treat the various shales most efficiently. Shale Oils are Variable. Many retorting tests have been made by the U. 2. Bureau of Mines on most of the important shales of the United States, with the result that knowledge has been gained which shows that identical methods of retorting do not produce similar oils from all abales, and furthermore, it is clearly evident that the sane shales when treated under different retorting conditions give markedly dif­ferent oils. It is also apparent that it may be impossible to produce equivalent oils from the different shales representing the major deposits of this country. Such results are to be expected when one thinks for a moment of what a great opportunity there has been for differences to exist in these shales due to differences of genesis o f the deposits. The many e; Digital Image © 2006 LEWIS C. KARRICK. All rights reserved. of the oil-shales, contained many changes in kind of plant and animal life from which the organic materials owe their origin, and the changing atmospheric conditions no doubt affected the degree of decomposition and alteration of the deposited material. ‘Jhese factors which might, at least, partly account for the very distinct difference between some oil-shale deposits* Of equal importance, possibly, are the influences of geochemical and physical processes which caused the x>**operties of the shale to alter, even within the same shale stata. Oil Yield is Indefinite. Under the head of oil-shale3 there is included a large class of rocks which contain greatly varying proportions of organic material* By definition, the organic constituent must yield oil when destructively distilled, or the rock is not an oil-shale* Now the word "oil" is just as generous a term as the word "oil-shale1* and as such, includes a great variety of organic substances, little re­gard being paid to the chemical constitutiomjor heterogeniety of mixtures* Consequently, it becomes necessary to observe, that the "oil yield" of a given sample of oil-shale, is the quantity of mixed hydrocarbons and their derivatives that is produced by destructive Digital Image © 2006 LEWIS C. KARRICK. All rights reserved.distillation, under definite conditions of pyrolysis; and for the sake of its commercial significance, there should toe included the idea of the relative comnercial value of this pro diet* The oil yield is not a fixed quantity, as in the assay of an ore for its metal content, hut is a 'variable with wide limits, and the quantity of oil obtained from the distillation of an oil-shale will depend on the conditions of operation, some of which conditions are now re­cognized. The quantitative limits of production of oil from an oil- shale, in which operation complete pyrolysis of the organic material is reached, will range from zero yield on one side where extreme destruction of the products of distillation is produced, to an in­definable numerical maximum oh the other side, where the minimum of secondary destruction takes place* In the former case extreme temperatures will be required with possibly the assistance of sane catalyst in order to effect the complete dissociation of the oil vapors into the two productss carbon and gas* The operations which will give the largest quantity of oil will include those conditions 7 Digital image © 2006 LEWIS C. KARRICK. All rights reserved. by which is produced the least free carbon and gas, both having remained associated in such combinations as to foxm "oil", in terms of our definition* Some of the conditions that work toward this objective will be discussed along with the explanation of assay methods* Quantity versus Quality* In striving to gain greatest quantity of oil while making the assay, one may sacrifice certain qualities desired' in the product, and obviously the problem with respect to its commercial application becomes one of marginal advantages of quantity and quality* 'Ihe assay should be performed under the conditions that will produce oil having properties as near as possible like the oil desired for commerce, and then conclusions should be drawn from the yield obtained as to the value of the shale in question. It is not necessary that the testing retort be a minature commercial plant in order to attempt such a scheme of determination, for it is easily demonstrated that wide variations in both quantity and quality of product can be realized by the application of certain simple retort­ing principles, which are conveniently applied in laboratory retorting Digital Image © 2006 LEWIS C. KARRICK. All rights reserved. and mast no doubt have rather wide limits of practical commercial application. It is quite possible that a successful comnercial retort will produce a superior product, as regards refinability, to that produced by the laboratory retort. One should keep in mind, however, that the determination is made primarily for ijuantitative data, but that in striving for maximum yield of oil in making the assay, the quantity of the oil obtained may differ considerably from that obtained under conditions that give oil of different pro­perties. A discussion of some of the reactions which are observed to take place during the pyrolysis of certain oil-shales# will suggest sane of the most Important factors which influence the variation in oil yields when the properties of the oil are caused to change by manipulation during retorting. Origin of Shale Oil (1) and (2) ___________The primary decomposition product of the organic component (1) Described in "Thermal Decomposition of Oil-Shale" by Ralph H. McKee and E* E. Iyder. (2) Data herein discussed were obtained in the laboratories of the U. S. Bureau of Mines. Intermountain Station. Salt Lake City. Utah. of oil-shales is a very heavy, high melting substance which is readily soluble in the conmon solvents of petroleum. This substance begins to be produced about 390°c in the shales tested; and under very 9 Digital Image © 2006 LEWIS C. KARRICK. All rights reserved.rapid heating it continues to form at temperatures as hig£ as 450°C* Were the temperature to remain for a long period at a temperature below 450°Cf it is likely that all the organic material would experience a complete change of state into the soluble form without the necessity of increasing the temperature* She greatest amount of soluble material that can be formed, will be slightly greater in amount than the combined weight of oil and gas that the shale will yield under average retorting conditions* The quantity of this material, however, that is available for recovery by solvents, will be less than the total weight of oil and gas that can be produced, due to the fact that some of the m aterial is simultaneously "cracked" inmedlately on its formation, and removed as oil distillate and gas* Not until a complete change of state is effected, at approximately 450°C, depending probably on the shale and the rate of heat supply, will the sum of the extractible material, the oil distillates and the gas, exceed slightly the total weight of the oil and gas which can be produced by a laboratory retorting test* 10 Digital Image © 2006 LEWIS C. KARRICK. All rights reserved. The curves in Figure I show the percentage relations of these various products throughout the critical range of tempera­tures of the shale undergoing destructive distillation. These curves were plotted from data obtained with the use of a rotary retort, pyrane trie ally c cut rolled, whereby the charge of finely ground shale durii^j rotation was continuously mixing and thereby insured that even heat distribution existed. The temperature of the shale was caused to rise rapidly and uniformly to the final oil-yielding temperature of the shale9 while simultaneously with­drawing at regular temperature intervals9 portions of the heat treated shale. On these portions were performed the determinations for percentages of soluble material produced. Arrangements wereNo n-C racked Shale Oils impossible* From the foregoing, it is quite evident that the oil recovered from the retorting of oil-shales, is a cracked distillate* Since the degree of cracking of petroleum seems to depend largely on the temperature, the time of reaction, the pressure and the influence of catalyzers, and since these factors are present to a rather important extent while destructively distilling the oil-shale, we may expect surely that shale oils will have characteristics that resemble cracked distillates of petroleum* It is well then to observe the factors which have been detennined to influence cracking of oils while making the laboratory retortii^ tests of oil-shales, and so modify the extent of the cracking influence as to produce desirable qualities in the oil recovered* Comparison of Shales Impossible Without Standard Testing Retort* A great deal of the preliminary work on oil-shales, done in the oil-shale laboratoiy of the U* S. Bureau of Mines, had to do with the use of a device for small scale retorting of oil- shales* The apparatus has come to be known as an "assay>v retort, and althougi the word "assay" is rather loose in its application to the testing of oil-shales, yet the retort has a good reputation V for reliability. Digital Image © 2006 LEWIS C. KARRICK. All rights reserved. It is free from eccentricity, and gives high yields of good products. The retort was developed for the purpose of deter­mining the oil yields from all classes of oil-shales under a wide range of operating conditions, and has proved itself capable of being easily operated. It will give very closely agreeing results from duplicate determinations, and is capable of flexi­bility in its operation so that many conditions of retorting can be employed* The oils which are produced are of very good quality, as the following table of results from a set of three distillation analyses will show. Oils produced from an American shale and a Scotch shale are used for comparison, and with them is included an identical distillation analysis of a crude shale oil produced by the Scotch commercial retort from average Scotch oil-shale. 13 Digital Image © 2006 LEWIS C. KARRICK. All rights reserved. Comparison of Shale-Oils made in Assay Retorts, and Scotch Shale Oil* Source of oil Scotch shale Retort- •Scotch Commercial Scotch shale Assay Shale from Soldier's Surrmit. Utah Assay ■ Yield of oil................................................. i Specific gravity of oil.......................... Setting point of oil,°C............................ | Distillation, first drop, °C................... per Cent distilled to 200°C..................... Unsaturation, 200°C. fraction percent. * Per cent distilled, 200°C -275°C........... Unsaturation, 200C*»27S° C fraction percent................................................... Vacuum fract ion to 200°C., Per cent..................................................... Specific gravity..................................... Viscosity................................................... Setting point, oc.................................. Vacuum fraction 200 - 225°C« Percent................................... Specific gravity*................. Viscosity................................ Setting point, °C................. Vacuum fraction 225°-260° 0., Percent............................ Specific gravity.................... Viscosity................................ Setting point, °C...................... Vacuum fraction 250°-27fiPc, • Percent................................. Specific gravity............... Viscosity........................... Setting point, °C........... Vacuum fraction 275°-300Pc Percent................................ Specific gravity............... Viscosity......................•.. Setting point, °C............. 0,877 28 49 12*22 28*0 23, 22 34*0 9.32 0*872 38 * 5,27 0* 881 40 * 7* 16 0*892 46 24*5 6* 13 0*902 52 29 6*07 0.911 60 34 18*1 0*864 32 44 16* 63 29*4 20.47 34*1 2* 10 0,868 38 « 4,38 0*872 41 * • 5*88 0*874 43 21.5 7.30 0*894 50 29 9*45 0*898 60 37 40,2 0*882 33 40 18*81 39*2 20*10 40*2 2*64 ** ** * 7*80 0* 880 42 * 9*20 0,889 48 18 14. 90 0*906 58 31*5 8* 88 0*928 72 40 * Not determined* **Q0mbined with next higher out. •14- Digital Image © 2006 LEWIS C. KARRICK. All rights reserved. The rate at which the heat is supplied to the assay retort has a very important influence on the properties of the oil formed. The curves in Fig. II indicate the direction in which a particular physical property of the oil tends to change with the change of rate of distillation. These data were taken from a long series of retorting tests and clearly show that when rapid retorting is employed, the yield of oil is a maximum, the specific gravity is high and the setting point high, while the percentage of saturated oils is low. With slow rate of retorting the yields are low and the oils have low specific gravities, low setting points but hi^ier value theref best f to whi saturated nilc. a*-- - Of^ DISTILLATION OIL PROOUCEI3, produced due to :atly alter the ield should, n decided upon as the probable use 2006 LEWIS C. KARRICK. All rights reserved. A Retort for Testing Oil-shales* In describing the "assay" retort and its method of operation, the writer suggests the use of this apparatus by those who desire to employ a method whose results are reproducible and retort whose operating characteristics are known* However, for con­venience and accuracy in rapid assays in the field and laboratory, and for providing a basis of comparison between assays, there is need for a retort and method wherein specifications are definitely fixed, and which will give results agreeing closely in duplicate determinations* No claim is made that the device and method will furnish sufficient data to warrant the outlay of any great amount of money in mine development or plant design* The retort is illustrated in Fig* III and the assembled outfit consists of the following essential partsj- 1* Gas burner, Fisher or similar type# 2* Cast iron amalgam retort, one pint capacity 3* Sheet iron asbestos lined jacket provided with built-in bottom with a hole to fit around top of burner* 4. A four-inch ring support* Digital Image © 2006 LEWIS C. KARRICK. All rights reserved. 5* Asbestos board cover* 6* l/4 inch street ell, screwed into lid for deliveiy tube* 7* 1/4 x 20-inch piece of galvanized pipe, straight* 8* l/4 inch Tee, upper opening reamed out to receive a one hole cork. 9* l/4 x 3 inch nipple, cut off at 45° angle at the plain end, and provided with a one-hole cork to fit into graduate* 10* Glass stoppered graduate, 100 cc capacity* 11* 60 linear inches of 5/l6 or 3/8 inch glass tubing for atmospheric condenser* All pip* threads should be painted with a coating of glycerine and pulverized calcined litharge before screwing tightly together* The best grade of corks must be used to fasten the graduate and condenser in place* zmwlijl. _ r 0/L-QHAL5 ASSAY RETORT. reserved.Care of Retort Important# Extreme care must be exercised in the preparation and maintainance of the contact surfaces between the lid and base of the retort* If the surfaces do not form a gas tight fit, they must be repaired by grinding them together by hand, using No* 200 carborundum and water* V/ith the lid clamped in an inverted position on a table, place the base in position with a small amount of grind­ing mixture between the surfaces, and rotate the base back and forth while pressing down lightly. After grinding, clean the parts care­fully with clean water and try the improved contact by clamping the lid in place and then forcing air into the retort with the lunges while immersing the retort in water. ‘Jlhere should be no leakage, and assurance can be had that no oil will be lost during the run. The use of gaskets and cecients between the contact surface is not recom­mended as no time is saved in their use and they conceal any evidence of leakage having taken place. Heat Control* A jacket is placed around the retort and a cover provided in order to insure evenness in heating. It is necessary that the Digital Image © 2006 LEWIS C. KARRICK. All rights reserved. same temperature relations persist throughout the entire run, that is, the bottom of the retort should be hottest, the sides not so hot and the top of lowest temperature* The top must be hot enough, however, so that, as the oil vapors begin to distil from the shale in contact with the bottom, there will be no condensation against the inner side of the lid, since the redistillation of this oil will cause losses and a great deal of undesirable cracking, by the oil dripping back into the shale* The temper ature of the sides should ndt be as high as the bottom, since in the early stages of the distillation much of the vapors will find their way to the exit by passing along the sidewalls where the opportunity for thermal decomposition is greatest* A short flame brought close to the bottom of the retort will cause the desired temperature relations to exist during the run* The retort should be filled completely with shale ground to pass a quarter inch sieve* If the shale is known to swell while heating, it may be necessary to reduce the charge slightly* There will be no bad effects produced on the evolved oil from packing the shale into the retort* However, some shales when heated, intumesce 19 Digital Image © 2006 LEWIS C. KARRICK. All rights reserved. and become so badly cemented together and to the sides of the retort that it will be found desirable to place the charge loosely within the retort. Finely Ground Shale Required for Best Operation. ' It is quite difficult to grind a rich oil-shale and there is a surprising amount of energy consumed in reducing, say, "forty gallon shale" to completely pass a quarter inch screen. Rolls are suitable for grinding if the feed is not allowed to flood and cause the production of much objectionable dust. By screening well between each pass there will be a minimum of .dust formed* IXist should be avoided since in retorting much is carried over into the oil and bad emulsions sometimes form* The desirable limits of fine grinding of the shale, for use in the assay retort, should be con­sidered irrespective of the labor required to produce the required fineness* There are certain thermal relations that are desirable, to obtain, and the use of finely ground shale works toward the realization of the ideal conditions* However, the poor heat conducting qualities of oil shale and the heat consuming reactions of the organic material nearest the source of heat limit, to a large extent, the possibility . Digital Image © 2006 LEWIS C. KARRICK. All rights reserved.of producing a uniform temperature throughout the shale charge when very rapid rates of heat supply are employed* It is desirable / to have all organic material approximately at the same temperature at the same time so that the pyrolysis will progress equally throughout the entire mass, and vapors of the same temperature will evolve simultaneously. In other words, there should be no temperature lag between the different parts of the shale charge* As the finely ground shale presents a much greater surface than coarse shale in proportion to its mass, there will be a tendency toward a more uniform pyrolysis throughout the charge when using fine shale since much of the heat, after distillation starts, is carried inwardly by convection, and more heat will be absorbed by the shale in a given unit of time due to the increased surface presented* It is impossible to complete a retorting test of coarse shale as quickly as fine shale and obtain a similar oil* Obviously each fine particle has practically the same temperature inside as on its surface, and, therefore, will destructively distil throughout 20 Digital Image © 2006 LEWIS C. KARRICK. All rights reserved. almost simultaneously* A large piece of shale, however, will reach the desired temperature on its surface in the same time as the small particle, but due to the temperature lag caused by the poor heat conducting property of the shale, the heat consuming reactions as distillation progresses iiwardly, and the heat carried outward from the interior of the shale lump in the total heats of the gases and vapors; there will obviously be a great temperature difference between the inside and the surface of the large lump of shale* The larger the diameter of the shale piece the greater will be the difference in temperature between the interior and the surface of the piece for any given rate of rise of retort temperature* In order to determine the magnitude of the temperature dif­ference, experiments were performed on a mass of shale four inches thick to which heat was supplied equally on all sides* The rate at which the temperature was raised was such that one and one-half hours elapsed while the entire mass of shale passed from the intial to the final oil-yielding temperature, or approximately three hours from the start to finish of the heating process* When the outside 21 Digital Image © 2006 LEWIS C. KARRICK. All rights reserved. or hottest part was beginning to distil at 365°C the interior had reached barely 100°C*, Also when the outside had completely finished distillation at 520°C the interior was only at 265°C, and finally when the interior was nearing the final oil-producing stage at 520°C, i the outside had reached 725°C* Such a temperature would very rapidly produce incondensibles and carbon from the oil vapors* Now oil vapors on issuing from the inside of a lump of shale are divided into capillary streams caused by the porous texture of the shale thru which they pass* This affords an excellent opportunity for them to receive all the super­heat that is possible from the highest temperature of the shale lump* Moreover, the vapors certainly must force their way out under pressure, and since the pores of the spent shale contain deposited cabon, a catalyzer of cracking, we must conclude that the conditions for cracking are ideally represented. Actual tests on shale, ground to different t finenesses, show that oil of a more cracked condition is produced from the coarse shale when treated in the assay retort under conditions which are best suited for retorting, fine shale* 22 Digital Image © 2006 LEWIS C. KARRICK. All rights reserved. The disadvantages produced from rapid retorting of coarsely ground shale, will be eleiminated if heating is controlled so as to take place very slowly. But here another difficulty arises, that of increasing the time of reaction and it has already been shown that the time is of great importance in effecting the decomposition of the oils formed. (See curves Fig. II.) Y/e are, therefore, forced to the adoption of a size of shale for a standard in the use of the retort that compromises the advantages against the disadvantages, and many tests have shown that minus one quarter inch shale is very convenient. Operation of the Retort. When the retort has been filled and tested for leakage, it should be placed in the support with the jacket, the graduate and condenser attached and the cover adjusted. die burner is lighted anu the flame regulated so that oil will start to appear in the graduated cylinder in about 45 minutes which is about the minimum time that the shale can be brought up to distillation temperature and yet have no portion of the charge below the condensation temperature 23 Digital Image © 2006 LEWIS C. KARRICK. All rights reserved. of the oil formed. This procedure will eliminate the possibility of losses occuring through redistillation of oil which might other­wise condense in the cooler part of the shale charge* When two or three cubic centimeters of oil have accumulated the flame should be increased since distillation must progress rapidly if it is intended to produce the minimum decomposition of the oil vapors and a maximum yield of oil* The oil should be produced at a uniform rate* An excellent sight control method for regulating the increase in in­tensity of the gas burner flame is afforded by the use of a manometer to indicate the pressure of the gas next to the burner* With this method of control the flame can be increased regularly by equal anounts by noting the corresponding increase in pressure shown by the manometer. If it is desired the accumulation of oil can be made to follow exactly any predetermined "time-quantity" curve for the shale in question. For any shale there is a maximum rate of retorting in excess of which the oil produced will suddenly become inferior in quality and yield. (See Curve 2, Fig# II.) This maximum rate of retorting should be determined by the assay retort for any new shale by making a series 24 Digital Image © 2006 LEWIS C. KARRICK. All rights reserved. of four or five retorting tests at different rapid rates. A curve can be drawn representing the oil yields obtained at the different rates, and it will show by its peak the rate at which the yield would be the greatest* (Fig* II. 2-hour rate) Check runs can then be made to get final data on the yield for this rate which will be the greatest possible yield with the apx^aratus. If the rate of accumulation of oil has been uniform during the retorting operations, there will be a sudden decline in the amount of oil produced per unit interval as the final oil is distilled off. The heat should be increased once more as soon as the decline begins since it is desirable to remove the last oil from the retort as rapidly as possible so as to minimize decomposition. > A white gas may appear at the end of the run, but this has been found to be non-inflamable and to carry no oil vapors.* The delivery tube should be kept fairly warn throughout the run in order to prevent congealing of the oil therein, and thus save delay in draining at the end of the run. When the bottom of the retort has become a dull red, it can be safely assumed that the distillation of the oil is at an end as this temperature is well afeove the final oil yielding Digital Image © 2006 LEWIS C. KARRICK. All rights reserved.temperature of any oil-shale* Determination of Yield and Precautions* Lack of experience in measuring the accumulated oil will cause a much greater error in results than lack of refinement in retorting technique. Since there is some dust and considerable water given off during the distillation, some of which occurs during the latter stages, there is little doubt but that much will remain in suspension in the partly congealed oil. By carefully warming and allowing plenty of time to settle, most of these impurities can be eliminated. Volmetric Method for Determining Oil Yield. The stoppered graduate and contents must be warmed until the oil is in a very fluid condition. Allow the oil to settle well, while keepii^j it in a very fluid condition. The graduate must be closed tightly during the time the oil is fluid to prevent loss of light volatiles. In order to read accurately the volume of the oil and water, it is necessary to assist the formation of a perfect meniscus lay releasing any oil and water droplets adhereing to the sides of the graduate* This is best accomplished by revolving the graduate between the palms of the hands while the contents are still ; Digital Image © 2006 LEWIS C. KARRICK. All rights reserved.warn* Read the upper level of the oil and then the lower level, if it is well defined and is not rendered obscure by emulsion, sediment, or clinging oil and water* The following procedure will facilitate accurate readii^ of the lower meniscus, and also provide against the possibility that water and sediment may not have settled out completely. Draw off with a pipette all except five cubic centimeters of the oil while still warn* Dilute the remaining oil with ten to twenty cubic centimeters of clean gasoline, and agitate gently till the emulsion disappears* Allow the shale-oil and gasoline solution to settle, then draw off all but five cubic centimeters and add gasoline as before* Bepeat as often as required until a clear meniscus results* How read the oil-water meniscus and subtract from the first reading to determine the total cubic centimeters of oil produced* From the number of cubic centimeters of oil obtained calculate the gallons of / oil per ton of shale* This method does not take into account the effect of temperature on the volume of oil* Gravimetric method for determining oil yield. For very accurate determination of oil, weight the graduate 27 Digital Image © 2006 LEWIS C. KARRICK. All rights reserved. and contents and allow to settle well, while warm. The graduated cylinder must be kept tightly closed. Then proceed to remove the oil by the method described below,and determine the weight of oil produced, by difference. Draw off with a large pipette all t&e oil except five cubic centimeters, and set it aside for specific gravity determination, as it will be a sufficiently representative sample of the total oil recovered. Great care should be exercised in pre­venting water or sediment fran being drawn into the pipette through bringing its tip too near the level of the water beneath the oil* Never draw down to within a quarter inch of the water level unless the oil is very clear and assurance can be had th^t the water-oil nemiscus is not disturbed. Dilute the remainii^ few cubic centi­meters of oil with twenty cubic centimeters of warn kerosene or gaso­line and while adding the solvent wash down the inner sides of the graduate with the solvent* »7hen all the water and solids have settled and the remaining shale-oil is well mixed with the solvent, 28 Digital Image © 2006 LEWIS C. KARRICK. All rights reserved. draw off the clear liquid to a safe distance from the level of the water, and discard it* Repeat this washing process several times, finally using petroleum ether, until a colorless solution of ether remains on top of the water and no shale-oil remains clinging to the walls of the graduate. Remove the ether to approximately the level of the water and eliminate the balance by evaporation. The last of the ether is very quickly removed by tipping the graduate as far to one side as possible, without spilling the contents and then revolving the graduate while directing a current of air into it; the ether is picked up on the side walls of the graduate during rotation, thus providing a large evaporating surface* As soon as the ether disappears, which will require scarcely a minute's time, weigh the graduate, now containing the water and sedinent only and subtract this weight from the original weight, the difference will be the total weight of the oil obtained from the shale. Determine the specific gravity of the oil first removed, with the Barrett or similar type 29 Digital Image © 2006 LEWIS C. KARRICK. All rights reserved. specific gravity bottle, and divide the weight of oil obtained by the specific gravity. The result will be the true cubic centimeters of oil produced at the temperature at which the specific gravity was taken. This value is converted to gallons of oil per ton of shale by use of the formula: Gallons of oil per ton of shale = Cubjp centimeters of oil X 240 Grams of shale used in retort# Duplicate volumetric determinations should agree within two per cent in the volumetric method, and in gravimetric determinations well within one per cent. The table of factors given below will facilitate calculations. For any given weight of shale used (column 1 or 2) select the corresponding factor in column 3. Divide the number of cubic centimeters of oil collected by this factor in order to convert into gallons of oil per ton of shale. For shale charges whose weights in grams are not an even multiple of ten, it will be necessary to interpolate to obtain the proper factor when using the following table. Preferably use a weight of shale vhich is an aven multiple of ten so as not to require interpolation. 30 Digital Image © 2006 LEWIS C. KARRICK. All rights reserved. FACTORS FACILITATING- CALCULATIONS tfeight of Retort Charge Grams Ounces Fact or Grams \ieight of Retort Charge Ounces Factor 1 2 3 1 2 3 10 •35 • 042 310 10,94 1.294 20 • 71 .083 320 11.30 1#335 30 1*06 .125 330 11.65 1.377 40 1.41 • 167 340 12.00 1.419 SO 1.76 • 209 350 12.36 1.460 60 2* 12 • 250 360 12.71 1.502 70 2.47 .292 370 13.06 1.544 80 2.82 • 334 380 13.41 1.586 90 3.18 .376 390 13.77 1.627 100 3.53 • 417 400 14.12 1.669 110 3.88 .459 410 14.47 1.711 120 4.24 • 501 420 14,83 1.753 150 4.59 ,542 430 15.18 1.794 140 4.94 • 584 440 15.53 1.836 150 5.29 .626 450 15.88 1.878 160 5.65 • 668 460 16.24 1.919 170 6.00 .709 470 16.59 1.961 180 6*35 • 751 480 16.94 2.003 190 6.71 .793 490 17.30 2* 045 200 7.06 • 835 500 17.65 2.086 210 7.41 • 876 510 18.00 2« 128 220 7. 77 • 918 520 18. 36 2.170 230 8.12 • 960 530 18.71 2, a 2 240 8*47 1.001 540 19.06 2.254 250 8.82 1«043 550 19.41 2.295 260 9.18 1.085 560 19.77 2.337 270 9.53 1*127 570 20.12 2,379 280 9.88 1.168 580 20.47 2.420 290 10.24 1. 201 590 20.83 2#462 300 10.59 1.252 600 21.18 2,504 An alignment chart, or straight line diagram. has been prepared by the U. S. Bureau of Mines, the use of which greatly faoi- lltates the obtaining of results on the basis of gallons of oil per ton of shale. This geometrioal method of calculating results requires the use of the following factorsi- weight of &ale used, and volume of oil X In cubio centimeters obtained from the retorting test; or for more . Digital Image © 2006 LEWIS C. KARRICK. All rights reserved.accurate results the weight of shale, the weight of oil obtained, rt and its specific or Baume gravity* Use of Steam in Retorting. Provision for the introduction of steam into the retort could readily be made by providing a connection to the bottom of the retort, or by passing a steam line down through a stuffing-box in the lid and penetrating to a point near the bottom of the shale charge* The use of steam in assays is not recommended due to the difficulty that will be experienced in controlling the supply to a degree that will give uniformity in results. The use of steam can produce slightly beneficial results if used under proper conditions, but it is quite often the case that^ very badly cracked oils are produced by the use of steam when its temperature greatly exceeds that of the oil vapors. Also the increased volume of vapors that must pass from the retort when steam is added, will cause much dust to be carried out into the collected oil, and emulsions will be formed* The breaking up of the emulsions so formed will often become a dif­ficult problem and accuracy in obtaining quantitative data will be sacrificed. Digital Image © 2006 LEWIS C. KARRICK. All rights reserved. A Rotary Retort Hay Give Valuable Data* Investigatdra desiring to obtain additional data on the temperature of distillation of the oil-shales, the character of the gases and oils given off at the different temperatures, the influence of rate of heating and fineness of shale particles on the oils pro- duced, etc*, will find an electrically heated horizontal rotary retort .very convenient# There need be no temperature lag between different parts of the shale charge in this type of retort, but there may be considerable difference in the inside, end, and center temperatures, of the shale charge, unless great care is used in designing the retort* A good rule is to reduce the length of the cylindrical shale container to not more than one and one-half times its diameter# Also provide a set of deflecting baffles of helical shale whose slope is nearly sixty degrees with the retort axis# These deflectors will direct the shale away from the ends and toward the center, thus causing continuous circulation# Many experiments performed in the laboratories of the U# S# i Bureau of Mines on different types .of retorts have demonstrated that 33 Digital Image © 2006 LEWIS C. KARRICK. All rights reserved. the rotary gives uniformly a more decomposed oil* The cause for this is largely in the opportunity for decompos it ion of the vapors due to their stagnation within the retort* It is also due to the great amount of excessively hot cracking surface that is exposed to the vapors* The retort walls are considerably hotter than the shale, and this tempera­ture difference will vary directly with rate of distillation, that is, the rate of heat supply* In order that there will be effected the necessary heat transfer to carry on the thermal decomposition of the organic matter at given rates, the heat difference between the heat transmitting surface and the shale must vary in i>roportion. The oil vapors having relatively very low specific heats, are readily super­heated to temperatures approaching that of the hot walls* Slower rate of heating reduces the superheat of the vapors but prolongs the reaction time* Steam or non-deletorious gases may be used to sweep the vapors from the retort before they become greatly overheated, but as a result the dust and emulsion problem will then become rather serious. The apparatus, however, has merit and is a means of getting much valuable information on the many varieties of shale while undergoing distillation. Digital Image © 2006 LEWIS C. KARRICK. All rights reserved. Its use in obtaining quantitative information on oil yield has not proved reliable* The Oils Produced Must Be Classified* Knowledge of the richness of a particular oil-shale is not sufficient to determine its value, without a fairly accurate idea being had of the relative value of the oil produced, in comparison with other shale oils and petroleums* Comparative data on the quality % of the oils is best obtained by making analyses of the oils by standard distillation methods. With minor exceptions, the method used by the Bureau of Mines for distillation analyses of shale oil is the same as that developed in the Pittsburgh Experiment Station and used in examining petroleum* It is briefly described in a recent report of the (3) Bureau issued in mimeograph form; it will be more fully described in (3) Dean, E* V/., Properties of typical crude oils from the eastern producing fields, Bureau of Llines, Reports of Investigations, Serial No. 2202, January 1921. Reprinted in National Petroleum News, Feb.9, 1921. and Oil and Gas Journal* Mar* 18-April 1* 1921*____________________ (4) a bulletin soon to be issued* (4) Dean, E. W., The Analytical Distillation of Petroleum, Bureau of Mines. Bulletin 207*________________________________________________________ 35 Digital Image © 2006 LEWIS C. KARRICK. All rights reserved. Bi6 method requires 350 cc of oil viiich quantity must be produced from a number of identical retorting runs* Three hundred cubic centimeters are required for the distillation in order to produce fractions large enou^i for separate examination. A fifty cubic centimeter sample v/ill be needed for determination of water percentage, specific gravity, setting point, and viscosity of the crude. Viscosities of small samples can be accurately determined by the use of pipette viscosimeters. The three hundred cubic centimeters are distilled in a standard fractionating apparatus under fixed conditionsf cuts being made for every 25°C rise in vapor temperature, tfhen the vapor tempera­ture has reached 275°C the last fraction is taken under these opera- % ting conditions. The oil is then allowed to cool, a vacuum receiver is attached to the condenser and the distillation is continued while maintaining the pressure inside the system at 40 mm. The fractions are then taken at 25 degree intervals till a vapor temperature of 300°C is reached, when the distillation is stopped and the fractions separately examined. 36 Digital Image © 2006 LEWIS C. KARRICK. All rights reserved. The shale oil fractions are examined by methods similar to those used for petroleum fractions, with several exceptions (a) Viscosities are taken at 60°C (140°F) instead of 100°?, due to the high content of solid x>araffin and hi^i boiling fractions in many shale oils* (b) Setting points are taken on the vacuum fractions instead of "cloud'1 tests. Setting point tests afford a means of direct com­parison of content of solid paraffin with commercial oils produced from shale in Scotland* (c) Unsaturation percentages are taken on the two combined fractions; the first includes those fractions distilling up to 200°C o o and the second the fractions from 200 C to 275 C. The fractions are produced while distilling under atmospheric pressure. Testing Small Amounts of Oil* A method is being perfected for the examination of samples of oil of 50 c* c . volume* The method will not give as much data as the complete distillation analysis described for large samples* However, information concerning the specific gravity, setting point, and viscosity 37 Digital Image © 2006 LEWIS C. KARRICK. All rights reserved. of the crude, the amount of oil distilling up to 275°C and its unsaturation may be obtained with a fair degree of accuracy* The use of the method is convenient for examination of the yield of oil from a single retorting test. Shales yielding at the rate of 25 gallons of oil per ton of shale will give sufficient oil for this test. A 100 cc capacity Bureau of Mines type of Engler gasoline distillation flask is used, the portion of the neck below the side outlet is filled with jack chain to act as a fractionating medium* The distillation is carried on at the rate of two drops per second until the vapor temperature reaches 275°C when the distillation is stopped and the volume of the distillate read and its specific gravity and unsaturation percentage determined. No effort is made to distil under vacuum in this method* Condensation and Recovery of "Scrubber" Naphtha* An atmospheric condenser has been found to be adequate for condensation of all vapors to a degree which is within the limits of accuracy of the retorts used and their operating methods* A water cooled condenser if maintained at a temperature well below that of the room will be found to collect a small amount of mi wViovi «.! A. Digital Image © 2006 LEWIS C. KARRICK. All rights reserved.shales are distilled at rapid rates. However, for field use a water . cooled condenser is practically out of the question, and unless a con­tinuous supply of cold water is available in all cases, it will be found expedient to use a train of absorption bottles containing mineral seal oil to catch the lightest portions of the oils. Even where a condensation is very complete, it will be found that a scrubber system will increase the recovery of oil nearly ten per cent, in retorting runs where conditions are regulated to give relatively large percent­ages of light oils. The scrubber oil must be "topped" before using to free it from the last trace of light oils which it may contain. The back pressure which will be caused by the use of the absorption train may cause leaks, if precautions are not taken to prevent them. In the laboratory a vacuum line may be attached to the end of the train and regulated so that a manometer placed near the condenser will indicate atmospheric pressure at this point. After the run the scrubber oil must be freed of the collected naphtha by again topping it using the same technique as was used in its original preparation. The recovery of naphtha should be figured in the total oil yield of the shale, but 39 Digital Image © 2006 LEWIS C. KARRICK. All rights reserved. should be recorded separately from the condensed oil* Nitrogen Content of the Shale Important* The commercial value of an oil-shale may depend to an important extent on its worth as a source of ammonia* The nitrogen contained in many shales may be recovered as ammonia by its reaction wi th hydro- (5) o gen at high temperature* A temperature of 700°C to 800 C is required (5) Production of ammonia from shales, by R. D* Howard, Lietallurgical Research Fellow* University of Utah. 1921* Thesis on file*____________________ to effect a 65 percent conversion of the nitrogen into ammonia, and approximately 900°C to convert over 80 percent* The ammonia is caught by passing the gas through a dilute solution of sulphuric acid, thus foming ammonium sulphate* tfith certain conditions of time, temperature, and superheated steam,(the steam reacts with the incandescent carbon of the spent shale and liberates hydrogen), as much as 90 percent of the total nitrogen of the shale has been recovered as amnonia in laboratoiy methods* Scotch practice averages between 60 and 65 percent recovery of the total nitrogen. The possible variations in the three factors influencing recovery so greatly effect the results in a determination for ammonium sulphate that it is reconmended that the total nitrogen be determined only. One can then allow an arbitrary 40 Digital Image © 2006 LEWIS C. KARRICK. All rights reserved. factor of efficiency for recovery of ammonia from a commercial operation on which to base his estimate of the value of the shale# One should bear in mind that a sixty percent conversion of nitrogen into anmonia will require a temperature of approximately 750°C and that oil-shale retorts that are to be used for anmonia production must be designed to withstand such temperature requirements. The temperature, it will be observed, is considerably higher than is required for complete distillation of the oil from the shale* A Keldjahl determina­tion for nitrogen is a very satisfactory method. Variations in Oi 1-Shales#. Oil-shales differ greatly in their chemical and physical properties# The minerals present in the oil-shales are as variable as in the dry shale rocks with which the oil-shales are associated. The mass of minerals present are best grouped in the great assembly of minerals that form all argillaceous, sedimentary rocks, iiuds from which the shales were formed are erosion productions and 41 Digital Image © 2006 LEWIS C. KARRICK. All rights reserved. were derived from all the rocks that were in process of weathering in the great drainage areas through which the eroded materials were transported to their final point of deposition* V/e find, therefore, that the proportion of certain minerals will increase in sane portions of a great shale stratum due to their proximity to the sources from which they were derived. Likewise with the increasing depth of dep­osition there was simultaneously taking place a change of x^oducts of erosion, as streams changed their courses and the weathering mountains changed their contours and presented new geological members to the elements. Under the microscope very little of the mineral matter can be clearly distinguished so extremely fine are most of the particles. The stain ii.^parted to the entire mass by the organic material renders less distinguishable many of the larger particles. However, crystals of quartz, calcite and pyrite may be observed, and in the fracture planes there is often thin flakes of selenite. Chemical analyses indicate the complexity of the aggregation of minerals and we note that the carbonates and silicates, among which classes the ft 42 Digital Image © 2006 LEWIS C. KARRICK. All rights reserved. minerals are chiefly represented, vary between wide limits in the domestic oil-shales* The organic substances which form the oils on destructive distillation, are present in greatly varying amounts* It is this material which imparts the unusual weathering characteristics to the shale ledges* The rich shales will withstand the destructive attacks of the elements to a much greater degree than the lean shales and as a result, we find the richer strata projecting furthest from the steep canyon walls and forming the resisting cappings on the brinks of the precipitons escarpments. In appearance oil-shales differ greatly* The richest varieties closely resemble a tough dark colored wood and depart markedly from the earthy appearance of most sedimentary rocks* Oil-shales exhibit in general, very somber colors but frequently strata will possess pronounced yellows and reds* The shale from near Dillon, Montana, is the most conspicuous, in that its principal gray color is set off by irregular patches of iri­descent colors on the fracture planes. One type of rich shale from illko, Nevada, has a rich chocolate color, while the most of the medium Digital Image © 2006 LEWIS C. KARRICK. All rights reserved.shales are light grayish brown. The shales occuring in the Green River formation range from grays and "browns in the lean types to very dark brown and blue-black in the rich types* One very rich variety of this shale is grayish black and has a distinctly satin lustre* The Devonian shales from the eastern i:>art of the United States are principally black and brown* However, the Illinois shale is distinctly of chocolate color. The shales usually weather to a blue gray on the surfaces. The rich shales are extremely difficult to break trans­versely to their bedding planes though most types will split fairly readily. The elasticity of the rich shales is very noticeable, especially the ••paper" type* Many places are to be seen where large thin sheets of paper shale will project several feet from the ledges, the outer edges drooping several inches under their own weight* The massive types of rich shale are extremely tough and resilient, and when these shales are being crushed, fragments, and oftentimes whole pieces will shoot with high velocity from the crusher jaws. These characteristics apply particularly to the shales Ykich 44 Digital Image © 2006 LEWIS C. KARRICK. All rights reserved. are capable of yielding, roughly, thirty-five or more gallons of oil per ton of shale* organic material in the shales is different both chemically and physically, probably in all shales as well as in many different parts of the same strata. Little is Known today of this material, and no doubt it will require special study and research in each particular oil-shale. 45 Digital Image © 2006 LEWIS C. KARRICK. All rights reserved.