Chemical Uses Promising for Fluorine A STAFF R E P O R T CHEMICAL applications appear more promising for fluorine at the moment th.an its use as a compressed gas, said J. F . Gall, Pennsylvania Salt Manufacturing Co., in a discussion before a recent meeting of "the Compressed Gas Manufacturers Assoeiation in New York. T h e picture Doay change, however, if and when larger c o n tainers are permitted for the shipment of fluorine. Fluorine was marketed in small pressure cylinders for the first t i m e last year, a n d its present cost was placed at around $20 a lb. to consumers. Three primary sources for fluorine were listed by E>r. G a l l —fluorspar, phosphate rock, and c r y o l i t e . Phosphate rock provides approximately 3 % of the fluorine supply, cryolite, o b tained from Greenland, about 13%>, wfcûle the remainder is obtained from fluorspar. T h e fluorine of commerce is manufactured through the electrolysis of a n hydrous hydrogen fluoride. T h e cell irsed for this purpose is somewhat siinpler in construction than the chlorine cell except that it has no diaphragm. The electrolyte within the cell is quite fluid a n d c o n sists of a solution of potassium fluoride in anhydrous hydrogen fluoride. T h e nxelting point is about 72° C. T h e anodes are made of carbon and the cathodes of steel. Fluorine is generated at the anode a n d is separated by a steel skirt from the hydrogen found at the cathode. "Relief ports" surmount each cell for protection against possible internal explosion. Shipped
as Compressed
Applica
tions
Fluorine is obtaining important applications i n industry. A few noted by D r . Gall were i n the manufacture of sulfur hexafluoride, a promising dielectric gas for high voltage applications; of uranium hexafluoride, employed in the manufacture of nuclear fuels and. the highly stable
perfluorinated hydrocarbons. Hydrogen» and fluorine as gases develop a considerable degree of h e a t and a torch for this purpose is considered practical. Fluorine combines vigorously with, silicon, and in fluorine, glass comes to full combustion. Asbestos will burn in a fluorine a t m o s phere, and a glass of water will also burn beneath a fluorine jet. Fission,
Demonstrated
. In a discussion and demonstration of t h e "future of atomic energy", John R. D u n ning, Department of Pbysics, ColumbiaUniversity, actually brought about t h e fission of an infinitesimal a m o u n t of uranium during the luncheon meeting of t h e association, employing radium and beryllium as neutron sources. T h e result was shown in full view of his audience on an ordinary cathode ray 'scope. T h e visible supply o f uranium, Dr. Dunning stated in reply to a question, is more abundant than "that of copper. Thorium, another fissionable material, is likewise plentiful, and whether these materials are SI or $10 a l b . , their costs are still a negligible factor. Other speakers at the t w o - d a y meeting held at t h e Waldorf-Astoria included I. Austin Kelly I I I , National E m p l o y e e Relations Institute; Howard A. Willis, C G M A ; Herrick L. Johnston, Ohio S t a t e U.; and Leon F. Bannigan, National Council of Private Motor T r u c k Owners.
Gas
Fluorine's properties create shipping problems, Dr. Gall said. I t must be shipped as a compressed gas. The critical temperature is —129° C., and cylinder pressure has been limited b y the Interstate Commerce Commission to 4 0 0 p.s.i. In the presence of air, F 2 is a s hazardous as chlorine, and if precautions are not observed, it can cause severe personal injuries. The speaker demonstrated a pressure gage which had been almost totally destroyed by the action of the element. The fluorine cylinders now being shipped hold approximately x/% lb., and for safety the 400 p.s.i. limit is utilized in a cylinder with 2,015 p.s.i. pressure specification. Connections to the cylinder valve are m a d e with a Monel adapter using a lead washer. Needle valves are recommended to control gas flow. Prior to shipment the cylinder is subjected to a temperature of 130° F., although this has been r a i s e d at times to 212° F. with no damage resulting to the cylinder. The cylinders for fluorine may be of the hot-drawn type, and u p to at least 400 p.s.i. m a y b e considered safe.
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Liquefaction offers one, method for the compression of fluorine. Liquid nitrogen is employed, and the product is cooled down to temperatures in the neighborhood of liquid air. The boiling point at atmospheric pressure is —187 ° C. and the pressure at the critical temperature i s about 880 p.s.i. T h e Germans in the last war are said to have used pressures for fluorine as high as 2,200 p.s.i. In this country, diaphragm-type compressors h a v e been employed for work at lower pressures—up to about 30 p.s.i. I n plants handling the element, all pipe lines a n d other equipment containing fluorine under pressure must be operated behind protective barricades. Plastic shields and rubber gloves are unsafe as they m a y ignite. Monel metal and nickel have been preferred in some i n stances for handling fluorine under pressure although for general use iron or copper pipe fines are satisfactory. Various disposal systems for waste fluorine-containing gases were described. In one, the products are scrubbed with water in a carbon tower.
Swedes Recover Oil from Shale D ETAILS of successful Swedish i n d u s t r i a l recovery of oil from shale were revealed in a paper presented by Gustav Egloff at the ACS Chicago section's technical conference Jan. 24. Production at t h e $25,000,000 Kvarntorp plant has reached some 2,000 barrels a day. Uranium oxide is one of the several by-products left in the oil-exhausted shale which contains 200 grams of t h e radioactive compound per ton. Sweden's shale oil deposits contain 500,000,000 pounds of uranium oxide, Dr. Eglofif estimates. Dr. Eglofif, director of research of the Universal Oil Products Co., who has recently returned from a trip to Sweden, reports that country plans t o make shale oil a permanent part of her fuel supply, tapping reserves estimated adequate for 500 years. A ton of shale yields 12 gallons of crude oil. Annual output from shale resources is reported at 225,000 barrels of gasoline, 32,000 barrels of kerosene,
CHEMICAL
and 325,000 barrels of fuel oils, as well as 22,000 tons of sulftir obtained as a by-product. In one of the four distillation methods used, a ground temperature of 100° F. is created by electrical heaters used t o force t h e vaporized oil u p out of the shale. The Swedes have grown more and larger vegetables in this tropically-heated soil which m a y require 30 y e a r s t o cool off. Dr. Eglofif describes t o m a t o e s three or four times normal size. Sweden turned t o shale in quest of fuel during the war when her fuel imports were virtually cut off. T h e Swedish Government, which operates the shale oil project, seeks to make it self-sustaining through use of all by-products. Production of chemical derivatives from the hydrocarbons of lower molecular weight and liquefaction of propane and butane are contemplated.
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