THE COLLIERY GUARDIAN JOURNAL OF THE COAL AND IRON TRADES. Vol. CXVI. FRIDAY, DECEMBER 27, 1918. No. 3026. Production of Oil from Mineral Sources.* By Dr. F. MOLLWO PERKIN, Ph.Dl, F.I.C., F.C.S. The organic matter in coals and cannels is generally described as volatile matter, and probably differs con- siderably in chemical character from the kerogen in shales; consequently, on being subjected to moderate heat different products are obtained, although they also are mainly of the olefine and paraffin series. At high temperatures, however, a different class of hydro- carbon is produced, mainly the benzene series; but this might also be the case if shale were subjected to high temperature in retorts similar to those employed for heating coal. Owing to the difficulty of maintaining even dis- tribution of heat in any carbonisation process, it is not easy to make certain of always obtaining the same products from a given material in the same propor- tions, and the form of the retort has much to do with the quantity and quality of the products obtained. In horizontal gas retorts the volatile matter first conies in contact with the highly heated arch and sides of the retort, and this causes radical changes in the volatile products, hydrocarbons of the benzenoid or aromatic series being largely produced. In a vertical retort the volatile products ascend chiefly through the cold incoming coal, and the resulting products contain a considerable proportion of hydrocarbons of a paraffinoid nature. Influence of Temperature and Time. In all methods of carbonisation the first action takes place at a very low temperature, and is the removal of occluded gases, the second being the volatilisation of the hydrocarbons of the coal itself, but it is diffi- cult to say when the one ceases and the other com- mences. Again, if a bituminous material is kept at a moderate temperature for a long time, practically the whole of the volatile matter can be removed, but the products vary with the time. When coal is sub- mitted to prolonged action of heat in a vacuum, the quantity of gas produced increases with the time, and the quality also varies as the reaction progresses. In horizontal gas retorts the volatile materials are further decomposed, and a smaller yield of tar is obtained than with a vertical retort. Furthermore, so thorough is the decomposition in horizontal gas retorts that complete splitting up of the hydrocarbon results, it is decomposed on the roof and sides of the retort and carbon deposited, whilst the tar itself contains more free carbon than that from the vertical retorts, and is consequently of smaller yield. Com- plete decomposition also takes place to some extent in vertical retorts, and some carbon is formed on the heated walls, but less than in the case of the horizontal retorts. On the other hand, with retorts heated to moderate temperature, say 450 degs. to 500 degs. Cent., against the 1,100 degs. Cent, of the horizontal and the 1,300 degs. to 1,400 degs. Cent, of the vertical, no carbon is deposited on the side of the retort, and the amount of free amorphous carbon in the tar is very small. Gas v. Oil Production. The retort temperature depends entirely upon the products required. For gas works, where a large volume yield of gas is required, high temperature is essential; but where motor spirit, fuel oil, lubricating oil and paraffin wax are required, low temperature carbonisation must be adopted. In low temperature carbonisation the gas produced is less than half that obtained by high temperature carbonisation, and con- tains less hydrogen and more hydrocarbons than the latter; low temperature carbonisation could therefore not be employed for the manufacture of gas for light- ing purposes. The main distinctions between high and low temperature are as follows: — High Temperature. (a) Large volume of gas, say 12,000 cu. ft. on the average. (b) Yield of sulphate of ammonia on average, say 20 lb. (c) Yield of tar on aver- age, say 11 gals, per ton of coal carbon- ised. (d) Tar is largely of aro- matic series, and yields benzol, toluol, naphthalene, anthra- cene, carbolic acid, cresols. These pro- ducts are the raw products for the manufacture of dyes, explosives, photo- graphic chemicals, drugs, and many other synthetic pro- ducts. Low Temperature. Low volume of gas, say 5,000 cu. ft. on the average. Yield of sulphate of ammonia on average, sav 10 lb. Yield of tar (crude oil) on average, say 20 gals, per ton of coal carbon- ised. Tar crude oil consists of hydrocarbons of the aliphatic series (paraffins, olefines and naphthenes). From the tar can be ob- tained motor spirit, fuel oil, lubricating oil and paraffin wax. The tai acids are useful for dis- infectants, but are of no use as raw products for other industrial purposes. * From a paper read before the Institution of Petroleum Technologists on December 17. It should be mentioned that when coals high in volatile elements and rich cannels are subjected to low temperature distillation much larger yields of crude oil are obtained, as much as 40 and 60 gals. (It is usual to use the term crude oil, and not tar, when speaking of the first product obtained by carbonising at low temperature.) Oils obtained by the carbonisation of bituminous material come under the same category as natural oils; they may therefore be classed as mineral oils, even although their origin was probably organic, as was that of natural oils; but many organic sub- stances, such, for example, as peat or w’ood, will give oils of a similar character when carbonised under suitable conditions. Retorts. The ordinary shale retort is not adapted for dealing -with caking bituminous material, nor, indeed, for treating cannel and non-caking coals; hence the larger amount of research work which has been carried out in the endeavour to devise a suitable retort for deal- ing with bituminous material which contains a large amount of fixed carbon, and will yield after extrac- tion of the volatile matter a good fuel for domestic purposes. The coke produced in gasworks contains a very low percentage of volatile matter, and is not adapted for burning in the ordinary grate. Coke produced by low temperature carbonisation (350 degs. to 550 degs. Cent.) is softer than that produced at high temperatures (about 900 degs. Cent.), and usually contains from 7 to 11 per cent, of volatile matter, which causes the coke to burn readily, practically without flame or smoke, and to give out a great heat. It is therefore very clean for household purposes, and if it were used instead of coal, the cost for paint- ing and decoration would be considerably reduced, whilst the atmosphere of large towns and cities would be very much less contaminated by smoke, and the living conditions would be healthier. Low temperature carbonisation also produces oils of the aliphatic series, which on refining yield motor spirit, fuel oil for internal combustion engines or for direct boiler firing, lubricating oils and paraffin wax, besids which there is a small quantity of ammonia and sufficient gas to fire the retorts and leave a small surplus. Combined Methods. In low temperature practice there are two possi- bilties either of which might be a financial success or they might be combined: (1) The production of oil and smokeless fuel; (2) the production of oil and the conversion of the fuel residue into power gas by gassifying it in a producer; or (3) the production of oil, using a portion of the fuel for domestic pur- poses and gasifying the remainder. In districts where power is not required for manufacturing pur- poses, but where coal or cannel could readily be obtained without long distance transport, then the first proposition would be the one to embark on; but where cheap power in large bulk is required, No. 2 would be the process to take up. The following examples are taken from practice, about 80 tons of coal being treated in each case: — (1) Coke produced in the Tarless Fuel Syndicate plant: Moisture 3’20 per cent. Volatile matter 987 Fixed carbon 74’54 Ash 12’59 Nitrogen 2’00 Yield of gas per ton 128,000 cu. ft. B.Th.U. of gas 139 Sulphate of ammonia 101 lb of24’5 percent. (2) Coke produced in Glover-West retorts, where the temperature of the flues was about 1,400 degs.: Volatile matter 1’31 per cent. Fixed carbon 86-90 Ash 927 „ Nitrogen 1’52 „ Sulphur 1-00 Yield of gas per ton ... 175,000 cu. ft. B.Th.U. of gas 132 Sulphate of ammonia... 23 lb. These two results show that the amount of sulphate of ammonia obtained is much larger with the low temperature coke than with high temperature coke. On the other hand, it must be borne in mind that in gas practice more than double the quantity of gas of high calorific value is produced than by low tem- perature carbonisation, and the initial yield of sul- phate is more than double that obtained in low tem- perature practice. One of the reasons why low temperature carbonisation has hung fire is due to the exaggerated claims made by inventors backed up by company promoters. In. all distillations of bituminous material water is obtained along with the oil, and is at times extremely difficult to separate, as the specific gravity of the crude oil approximates to that of water; in fact, it is not unusual to find 30 to 40 per cent, of water in the crude oil. This has all been lumped in as oil; hence the impossible claims for oil yields which have been made. An export tax on coal is advisable, if only as a means of helping to pay for the war. Further, as a means of effecting economy in the utilisation of coal, the burning of crude coal in open domestic grates should be abandoned and the coal first subjected to treatment to remove the bulk of the volatile matter, the use of the resultant smokeless fuel being compul- sory. Even if this should not result in an actual saving in the coal mined, all the products which could be obtained from it would be utilised, and there would be no waste. If all the coal used for domestic pur- poses—amounting in 1903 to 35,000,000 tons and now about 45,000,000 tons—were partially carbonised, the production of crude oil—at the rate of 20 gals, per ton, a low figure—would be from 700,000,000 to 900,000,000 gals, per annum. The yield of sulphate of ammonia at 10 lb-, per ton would give 156,000 tons per annum. The dust left in the workings in coal mines is generally of the same composition as the coal, and if brought to the surface could be treated by low tem- perature carbonisation, and smokeless fuel and by- products produced from it. The author recently received a sample of such a coal, which gave the fol- lowing analysis: — Per cent. Volatile matter (on dry material) 28*47 Ash............................ 21*41 Fixe i caroon.................. 50’12 This coal coked very well, and after the volatile matter had been taken off could be gasified in a pro- ducer. The ash was rather high for the residue to form a satisfactory domestic fuel. At present about 700 tons of this coal are being brought to the surface and thrown on to the dump heap annually, whilst throughout the country thousands of tons of coal are being mined and brought to the surface merely to be dumped on the waste heap. In order to get the greatest use out of the coal, undoubtedly the common sense method was to carbonise or semi-carbonise, obtain the by-products from it, and produce a fuel which could either be gasified in a producer or em- ployed as a domestic fuel. The Government had been pressed to give facilities for testing various retorts to ascertain which would be the best for big scale work; but instead had approached the gas works and asked them to produce the fuel oil. This, however, could not be done, except in the form of creosote, at the same time as the benzol and toluol required by the Government. Nevertheless, the gas engineers had risen to the occasion, Dr. Colman, Mr. West, and Mr. Bond having worked at a process for steaming on vertical retorts, and suc- ceeded in producing a fairly good fuel oil. The Mineral Oil Production Department undertook to adapt the following installation of retorts: — Tons of coal per day. Nottingham (started May 1918) treated 150 Dundee (started Sept. 1918) „ 200 Bradford (started Sept. 1918) ,, 200 Bolton (never completed). Nelson (never completed). Of these, Nottingham worked seven months, and produced 945,000 gals; Dundee and Bradford worked 2j months, and produced 450,000 gals, each, making a total production of 1,845,000 gals. The cost of con- version of the retorts was £100,000. The average cost of materials treated was 25s. per ton. The average amount of distillate obtained was stated to be 30 gals, per ton of material carbonised, which made the cost of the oil Is. per gal., excluding labour and operating charges. Another point was that the coke was prac- tically valueless owing to the action of the super- heated steam on the free carbon. Discussion. The President remarked that Dr. Perkin had first stated that the yield of sulphate of ammonia with low temperature distillation was very much lower than with high temperature distillation, but the examples he had given showed a very much greater yield with low temperature than with high temperature distilla- tion. Now that the censorship was over he hoped that every possible light would be thrown on this question in view of the enormous importance of it, both from the economic and the national point of view. Prof. J. S. S. Brame regarded it as a very great tribute to British industry that the shale oil industry had held its own and developed as it had done in face of overwhelming natural difficulties. He thought that augured well for the future in the matter of low temperature distillation of other products than shale. There were, however, a large number of problems that would have to be solved before we came to the success- ful production, in large quantity, of oil suitable for general purposes, and which would compare with the natural petroleum oils. A great deal had been done in recent years, but the results were very often con- tradictory. That probably arose from the fact that coal itself was such a complex substance, and gave a reason why people in the United States got different results from those obtained in this country. They were probably working with a very different raw material. It was extremely difficult, with a problem