Discussion
T h e conditions giving the highest filtering rate and highest recovery were: reaction time, 1 hour; reaction temperature, 200' F.; st rrer tip speed, 50 feet per minute; proportion of sulfuric acid to rock, stoichiometric for the calcium in the rock. T h e principal advantage of the process is the production of acid containing 40% phosphorus pentoxide instead of the usual 28 to 32%. Acid of the higher concentration can be used directly, without further concentration, for some processes such as the production of ammonium phosphates. If the acid is to be concentrated further to 54% phosphorus pentoxide, only half as much water needs to be evaporated as ivhen starting with 307' acid. Another advantage of the process is the smaller extraction system; \\,ith the shorter time and more concentrated acid. the size of the reaction system probably needs to be only 2074 of that required for the gypsum process. Also. filtration in this process is less sensitive to conditions of operation, such as control of sulfate concentration. Details of the mechanisms and the interactions of variables are less understood in this process than in the conventional gypsum process, which even today is applied much in the sense of a n art. The new process has great potential, however. and TVA has advanced it to pilot-plant development while continuing the bench-scale study.
Preliminary operation of the pilot plant a1 a rate of 500 pounds of phosphate rock per hour has demonstrdted that the pilot-p!znt reactor gives the same type of agglonierates of calcium sulfate hemihydrate as was obtained in the bench experiments. Filtration rates have been satisfactory. Difficulties n i t h the continuoub filter have led to low recovery, but this situation is viewed as temporary. literature Cited (1) Higiiett, T. P., Phosphorus arid Potassium. No. 4, 24-9 (Decem-
ber 1962). (2) Jones, S. A . , Chem. Eng. 6 7 , KO.17, 150 (1960).
(3) Nelson: G., "Development and Application of Some Rapid Anal)-tical Control Methods in the .Manufacture of \Vet-Process Phosphoric .kid," Technical Meetings, International Superphosphate Manufacturers' Association, IViesbaden. German), Sept. 11 to 15, 1961. (4) Xordengren, Sven, Iiig. I'eteriskaps .4kud., Huridl.! S o . 203 (1949). (5) Peet, K .B.: U. S. Patent 2,885,264 (May 5, 1959). (6) \Veber, \V. C.. Edwards, \ V , . Fertzliser Soc. (Engl.) Proc., No. 67 (1961). (7) \Vilde! \V. D.; Chern. En?. Prog. 5 8 , No. 4, 92-4 (1962). RECEIVED for review .\pril 2, 1964 Accwmn June 22. 1964 Uivision of Fertilizer and Soil Chemistry, 145th ,ACS Meeting. New York, N. Y., September 1963.
SENSITIVITY TESTING AND FIELD HANDLING OF SUPERCRITICAL ACETYLENE G
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Air Reduction Co.? Inc., .\fitrray
Hill, .V. .J,
To assess the feasibility of loading supercritical acetylene in a large tank and releasing it at high rates, samples of supercritical acetylene with density in the range from 1 3 to 16 pounds per cu. foot were subjected to high temperature, explosive shock, mechanical shock, ignition b y flame, and rapid venting operations. The results of these tests showed that supercritical acetylene presents no more explosive hazard than TNT and that sounding rocket experiments could be made with supercritical acetylene in a payload tank.
. ohjection to the use of supercritical acetylene \.vas it, i i n k n o \ \ t i scniitivity. F,mpiriral tccts designrd to simulate i rpi c,c.ritativr ignition w u i res \ I-gallon tlokr cylinders. Presure i i i the, tt,wrvuir i v a k indicatrd ti>- a Bourdon gage. 'I he trst sanlplc coiitiiinrr3 having a known volume. \vas immersed in a bath of d i ? icr and trii-hloroeth) lrne. Opening the hand vailvt. h t \ \ W I I the rercrvciir and the sample container allo\ved ac~ctylctirto c.otideiise in the sanif,lr conrainrr. ' l h e amollnt \ v a < In(,aothat iveight decreased only by the amount of acetylene actual1)- delivered to the payload tank. Xeoprene garkets cut to fit the tank formed the ends of the box used to contain t h r coolant ( d r y ice and trich1oroeth)-lene) for condencine; the acetylene. .After conden
