SUMMARY OF INVENTION 65 It is an object of this invention to provide an im- proved process of making HMX which provides both high power, and extreme insensitivity, at a price which The special insensitivity of this HMX is due to several factors, each of which must be held in tight tolerance. The particle size must be kept to about 1 to about 5 micron in range, the polymorph must be alpha, and the purity must be very high. To obtain the right poly- morph the amount of nitric acid used must be carefully controlled as too high or too low a dilution could cause the formation of gamma HMX. Further, the tempera- ture of the reaction must be kept as close to room tem- perature as possible because if the temperature rises above 45 degrees Centigrade, the product again ob- tained is gamma HMX, instead of alpha HMX, the de- sired product. To obtain the right size, the product must be precipitated with great agitation in the manner de- scribed with a high speed mixing turbine at about 15,000 RPM. The purity of the product must be upgraded using the solid phase up-grading techniques hereinafter described. Failure to follow any and all of the steps in the procedure, may seriously compromise, if not pre- vent the establishment of the special property of insensi- tivity to this alpha HMX material. EXAMPLE 1 Nitration of TAT with a mixture of nitric acid and phosphorous pentoxide. 250 grams, within the effective range of 200 to 300 grams, of 98% nitric acid were introduced into a 500 ml. beaker, provided with a thermometer, and a magnetic stirring bar. 70 grams of phosphorous pentoxide were then added in portions over a 30 minute period. The addition was made with stirring via the magnetic stir- ring bar and the rate of addition of the phosphorous pentoxide was dictated by the temperature of the reac- tion mixture, which was not permitted to rise above 35 degrees Centigrade. The reaction mixture was allowed to stir covered by a piece of aluminum foil until the temperature fell to room temperature. 50 grams of TAT were then added in about 4 equal portions at such a rate that the temperature was prevented from rising above 40 degrees Centigrade. The reaction mixture was al- lowed to fall to room temperature, and the stirring bar was removed when all signs of any exothermic action had subsided. The beaker was covered by aluminum foil and allowed to set undisturbed for 16 hours at room temperature. During this time the entire reaction mix- ture sets-up to a cream cheese like consistency. The reaction mixture is discharged directly into the vortex of a room temperature water bath stirred by an L-TEC air turbine mixed, (see U.S. Pat. No. 4,424,677), specifically designed for very high speed mixing and dispersing. The water acts to brake the reaction com- 4 plex, and precipitates the alpha HMX, guaranteeing the formation of extremely small particles (crystals). The solid crude alpha is filtered, and washed with as much cold water as necessary to reach a constant of 7 ph. (This water should be maintained between 10 to 35 degrees Centigrade to prevent any digestion of the size of the crystals. The filtered but damp cake is then dis- persed in 6 to 8 times its mass of agitated boiling water. The total washing time should not exceed 2 minutes in order to prevent size enhancement via digestion. The washed crude HMX, which should have no odor, is METHOD B The quantities and methods as in Example 1 above, however, a water proof container is employed and the mixture is placed in a constant temperature bath at 40 degrees centigrade. The thickness of the paste in the container is limited so as to permit attainment of bath temperature throughout the mixture in a reasonable period of time. If necessary the mixture may be stirred mechanically. Under these conditions the upgrading time is reduced to approximately 4 hours. then filtered hot, and rinsed with cold water. This cur- METHOD C tails crystal digestion before being thoroughly dried. The drying may be simple air drying, or vacuum drying at a temperature near 50 degrees Centigrade. The still crude HMX must now be up-graded in pu- rity before use. This is accomplished by anyone of the following methods. PART 2 The same quantities were used as set forth in Example 1 however, the mixture is fed through a heated screw mixer or feeder for rapid mixing and temperature equili- bration. The temperature may be adjusted upwards to the 70 degree region reducing the reaction time to a matter of minutes. RESULTS METHOD A Purification of the contaminated HMX produced above by trituration with a nitric acid/phosphorous pentoxide mixture. 100 grams of the contaminated HMX are added por- tion wise to 100 grams of nitric acid (about 70 ml.), within the effective range 80 to 120 grams, containing 12.5 grams, which is within effective range 10 to 14 30 grams, of phosphorous pentoxide. The container may be a simple beaker which may be covered with alumi- num foil. The quantity of nitric acid used here may be increased (not above 1 30 grams) for easier mixing of the mixture. The quantity used here has been found to be 35 given about as thick a mixture as is practical. The quan- tity of phosphorous pentoxide may be reduced or in- creased depending for the greater part upon the amount of water originally present in the nitric acid and the amount of SEX present in the sample. The quantities 40 used here have been found to work well over a very wide range of sample purities with initial melting points as low as 230 degrees centigrade. The phosphorous pentoxide should be fully dissolved and contain no solid particles. The nitric acid may be prepared ahead of time 45 and kept as a stock solution. The HMX must be free of DANNO (l,5-diacetyloctahydro-3-nitro-7-nitroso- 1,3,5,7-tetraazocine), since contamination with this The impact values obtained via the “ERL, Type 12 Impact Tester” using a 2 and one half kilogram mass, demonstrated values 5 to 10 times greater than normally achievable with “Class 5 Beta HMX”, and kinetic en- ergy values 10 to 20 times greater than normal, As the following actual data indicates DROP Initiation y = yes, n = no 100 cm drop n 100 cm drop n 100 cm drop n 100 cm drop n 100 cm drop n 100 cm drop n 100 cm drop n 100 cm drop n 100 cm drop n 100 cm drop n 150 cm drop n 150 cm drop n 150 cm drop y 150 cm drop n 150 cm drop n 150 cm drop y 150 cm drop n 150 cm drop y 150 cm drop n 1 50 cm drop y compound can cause dangerous fume-offs. The gradual addition of the HMX to the nitric acid solution is to 50 Do t0 tbe dam age being caused to the test apparatus facilitate the mixing as no exothermic action should by the lar 8 e amount of kinetic energy released from occur. The paste is left for about 16 hours at room tern- sucb S reat dro P heights it was decided to accept the perature, samples may be taken to determine comple- 50% initiation value as being somewhere above 150 cm. tion of the reaction. Reactions have been intentionally ANAT Y
Saturday, December 16, 2017
wlcome ! making a highly impact insensi- tive form of HMX called Alpha HMX - having an average particle size of 5 microns "HMX, which is known as l,3,5,7-tetranitro-l,3,5,7- tetraazacyclooctane, is the most powerful non-atomic 25 explosive in military use...The special insensitivity of this HMX is due to several factors, each of which must be held in tight tolerance. The particle size must be kept to about 1 to about 5 micron in range, the polymorph must be alpha, and the purity must be very high. To obtain the right poly- morph the amount of nitric acid used must be carefully controlled as too high or too low a dilution could cause the formation of gamma HMX..."
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