Shale Oil

SHALE OIL. The shale oil industry, although known in France in the early part of the 19th century, owes its existence in its present form to Dr. James Young, who, in 185o, obtained his well-known patent for producing paraffin oil and paraffin from bituminous coal by slow distillation. This process was even worked in America until the discovery of petroleum. The industry has been centred in the Mid-Lothian area of Scotland since 1862 and an average of about three million tons of raw shale has been raised for many years. The oil shale of Scotland is dark grey with a laminated or horny fracture. Its specific gravity is about 1.75. The oil consists chiefly of paraffins and olefins.

Shales are widely distributed throughout the world. The French industry is older than that of Scotland; the deposits in New South Wales are very much richer than those of Europe and yields of over Ioogal. per ton have been quoted; in Germany there are vast quantities of lignites and brown coals that are being worked vigorously; while in Colorado and Utah there is an immense potential wealth of this material.

The world-wide exploitation of oil shale, however, is dependent entirely on the exhaustion of petroleum and there appears to be no immediate likelihood of any shortage in this direction. The world's annual production of mineral oil is approximately 15o million tons.

Shale Oil Refining.

Originally, horizontal retorts similar to those in coal-gas manufacture were employed. The first step in advance was made by Henderson in 1873 when vertical retorts with a capacity of i8cwt. were arranged in groups of four and charged in rotation. The outlet for the oil vapours was at the lower end of the retort, and steam was blown in copiously to assist in the uniform heating of the shale and to remove oil vapours. The later Henderson retorts worked continuously and were gas-heated. The upper part was of cast iron and heated to about 900° F whilst the lower part was fireclay maintained to about 1,30o° F. The charge in the retort travelled downwards

owing to the periodical removal of spent shale at the bottom and no shale passed into the fireclay section until it had yielded all its oil. In the lower section the high temperature and the presence of steam brought about the removal of the nitrogen in the shale in the form of ammonia. The vapours from the retorts passed through air condensers in which ammoniacal liquor and crude oil were separated. The uncondensed gas was stripped of its light gasolene and used as fuel.

Crude shale oil is dark in colour and has a specific gravity approaching 0.890 and a setting point of about 90° F. It contains about 8o% of hydrocarbons together with pyridine bases and cresols. In the refining of shale oil, ample steam is used in the stills, which are continuous in opc ration. The various fractions are agitated with acid and soda and again redistilled into crude naphtha (up to 0.770 specific gravity) and to burning oil (up to 0.850 specific gravity) and into "heavy oil and paraffin" which is solid at ordinary temperature. The acid and soda treatment and redistillation is repeated on the lighter fractions, whilst the solid paraffin is separated by chilling and pressing from the lubricating oil base—so that finished naphtha, burning oil, solid paraffin and lubricating oils are ultimately obtained.

The following table gives an average yield: Gasolene and naphtha 6.90% Burning oils . 31.84% Intermediate and lubricating oils 23.97% Crude paraffin wax • Loss • • • From the ammoniacal liquor ammonia is driven off by the application of heat and lime, the liberated gas is brought into contact with sulphuric acid and converted into ammonium sul phate, a by-product that has been of considerable importance in enabling the industry to hold its own against competition. (See