Classifications

• • C—CHEMISTRY; METALLURGY
  • C06—EXPLOSIVES; MATCHES
  • C06B—EXPLOSIVES OR THERMIC COMPOSITIONS; MANUFACTURE THEREOF; USE OF SINGLE SUBSTANCES AS EXPLOSIVES
  • C06B45/00—Compositions or products which are defined by structure or arrangement of component of product
• • C—CHEMISTRY; METALLURGY
  • C01—INORGANIC CHEMISTRY
  • C01C—AMMONIA; CYANOGEN; COMPOUNDS THEREOF
  • C01C1/00—Ammonia; Compounds thereof
  • C01C1/18—Nitrates of ammonium
• • C—CHEMISTRY; METALLURGY
  • C01—INORGANIC CHEMISTRY
  • C01D—COMPOUNDS OF ALKALI METALS, i.e. LITHIUM, SODIUM, POTASSIUM, RUBIDIUM, CAESIUM, OR FRANCIUM
  • C01D9/00—Nitrates of sodium, potassium or alkali metals in general
• • C—CHEMISTRY; METALLURGY
  • C05—FERTILISERS; MANUFACTURE THEREOF
  • C05C—NITROGENOUS FERTILISERS
  • C05C1/00—Ammonium nitrate fertilisers
• • C—CHEMISTRY; METALLURGY
  • C05—FERTILISERS; MANUFACTURE THEREOF
  • C05C—NITROGENOUS FERTILISERS
  • C05C1/00—Ammonium nitrate fertilisers
  • C05C1/02—Granulation; Pelletisation; Stabilisation; Colouring
• • C—CHEMISTRY; METALLURGY
  • C06—EXPLOSIVES; MATCHES
  • C06B—EXPLOSIVES OR THERMIC COMPOSITIONS; MANUFACTURE THEREOF; USE OF SINGLE SUBSTANCES AS EXPLOSIVES
  • C06B23/00—Compositions characterised by non-explosive or non-thermic constituents
  • C06B23/002—Sensitisers or density reducing agents, foam stabilisers, crystal habit modifiers
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
  • Y10S—TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y10S149/00—Explosive and thermic compositions or charges
  • Y10S149/11—Particle size of a component
  • Y10S149/112—Inorganic nitrogen-oxygen salt

Definitions

• the present invention relates to improvements in the production of ammonium nitrate compositions, and is especially applicable where it is required that the composition should be in a form in which the crystals are tightly compacted together, for instance when it is to be formed into compressed masses or into granules produced by comminution to a limited extent of larger compressed forms.
• the stable crystal form of ammonium nitrate is a rhombic bipyramidal form of specific gravity 1.716, designated by the Roman numeral IV; between the transition point occurring at 323 C. and the other transition point occurring atv 84 C. the stable crystal form is rhombic and of specific gravity 1.654, designated by the Roman numeral III, and between the last mentioned transition point and the one occurring at 125 C. the stable crystal form is tetragonal designated by the Roman numeral II.
• ammonium nitrate compositions suitable for-use for instance as explosive, propellent and power gas pressure producing charges, smoke compositions, insecticidal and fungicidal vaporizing charges and the like by casting fusion mixtures is of somewhat limited 'guanidine nitrate or 'nitroguanidine.
• compositions suitable for use e. g. as explosive propellant, gas pressure, smoke, insecticidal or insect repelling or fungicidal charges, or as fertilizers, which mayinclude other appropriate inorganic and/or organic constitutents e. g. trinitrotoluene and other explosive bodies, alkali metal chromates, ammonium bichromate, phosphates, chlorides, sulphates, oxalates, vapourisable insecticides,
• the process for the production of compositions comprising ammonium nitrate and potassium nitrate comprises mixing together ammonium nitrate and powdered potassium nitrate and maintaining the mixture thus formed within a temperature range of about 32 C. and about 100 C. for a time long enough to ensure that the ammonium nitrate is stabilised substantially as modification III.
• ammonium nitrate used for mixing with of powder or small granules.
• At least 8% potassium nitrate reckoned on the sum of the ammonium nitrate and potassium nitrate is found to be required to attain stabilisation of the ammonium nitrate in form III, where stability is required at temperatures of the order of 10 C., but quantities say from 1% upwards may be sumcient for practicable purposes Where such low temperatures are not reached e. g. to prevent the breaking up of granular fertilisers or compressed pellets, under appropriate circumstances.
• potassium nitrate e. g. inorganic salts, such as chromates, phosphates; ammonium oxalate, In other in the range between 32 C. and about C.
• the diffraction pattern ultimately attained by the method of our invention is almost indistinguishable from that obtained from a cooled and powdered fusion mixture containing the same proportion of ammonium nitrate and potassium nitrate.
• potassium nitrate in place of potassium nitrate there may be used other water soluble potassium salts that react metathetically with an excess of ammonium nitrate to form potassium nitrate; for example, potassium sulphate, potassium chloride, potassium dihydrogen ortho phosphate, potassium oxalate, and potassium chromate.
• potassium sulphate potassium chloride
• potassium dihydrogen ortho phosphate potassium oxalate
• potassium chromate potassium chromate
• potassium nitrate When potassium nitrate is used it is desirably in finely powdered condition.
• the ammonium nitrate may be in ordinary crystal powder condition, but the invention is also applicable for the treatment of ammonium nitrate granules produced by a spray process.
• compositions produced according to the process of the present invention have been found to be particularly suitable in the production of compressed charges comprising ammonium nitrate and potassium nitrate.
• Example I The ammonium nitrate was in the form of crystal clusters passing a 60 mesh British Standard Specification screen and contained 0.1-0.2% moisture. 450 parts of this ammonium nitrate were ground together with 50 parts pulverised potassium nitrate having a grist fine enough to pass a 1'70 mesh B. S. S. screen, until the whole of the product passed through a 100 mesh B. S. S. screen, the mixing being conducted at room temperature. An X-ray powder photograph of the 'mixture at this stage was the same as that of a sample of ammonium nitrate in form IV, and even after storage at 18 C. of a sample of the mixture for two weeks the X-ray photograph was still substantially the same.
• the rest of the freshly ground material was heated to 45 C. and stored at that temperature for 18 hours, and then allowed to cool and, was kept for a week at room temperature.
• the X- ray powder photograph was substantially identicalwith that obtained from a solid solution of potassium nitrate and ammonium nitrate of the same percentage composition prepared by fusion and cooling, and was also substantially identical with that of a sample of ammonium nitrate I11. Further heating at 45 C. for 6 hours produced no detectable difference in the X-ray photograph.
• Pellets of the composition 1 in diameter compressed under a pressure of 2 tons per sq. in. showed a diametric expansion of only 1.56% after 16 temperature cycles between and 50 C. and did not crumble or crack.
• Compressed pellets made from a pulverised congealed fusion mixture of the same percentage composition showed about the same diametric expansion when similarly cycled.
• the pulverulent mixture may be mixed with e. g. potassium chromate and ammonium bichromate and gamma hexachlorocyclohexane and compressed into pellet form, to give an insecticidal vapour generating pellet which will not crumble with temperature variations on storage,v or it may be mixed with trinitrotoluene and pelletted to give an Amatol explosive that will resist volume changes tending to shatter it on alternating hot and cold storage.
• Example II The ammonium nitrate used was spray crystallised material passing a 16 mesh and retained on a 25 mesh B. S. S. screen, and had an initial natural bulk density of 0.917 grams per 0. 0. 0. Four temperature cycles between 0 C. and 50 C. sufficed to reduce the natural bulk density of a sample of this material to 0.778 grams per 0. c. and to cause serious cracking and disintegration of the granules. The remainder of the granular material was mixed with of its weight of potassium nitrate of grist fine enough to pass through a 200 mesh B. S. S. screen, after the granules had been moistened with 2% of their weight of a saturated solution of ammonium nitrate in water, these operations being conducted at room temperature.
• the moistening of the ammonium nitrate granules enabled the potassium nitrate particles to adhere to them instead of segregating away from them.
• a small portion of the mixture was stored at 20 C. for 24 hours, and a heating curve was plotted for it. This indicated a sudden break at approximately 32 C. showing that the ammonium nitrate was still present below that temperature in form IV and Was undergoing transition into form III at approximately 32 C.
• the remainder of the mixture was heated to 50 C. and stored at that temperature for 24 hours, and was thereafter cooled to room temperature, and a heating curve plotted for it. This heating curve showed substantially no evidence of a break between 0 C.
• Example III 450 parts crystalline ammonium nitrate as used in Example I were ground together with 50 parts potassium oxalate with a grist fine enough to pass a 170 mesh 13. S. S. screen until the Whole passed through a mesh screen, these operations being conducted at room temperature. The ground mixture was then heated to 50 C. and maintained at the temperature for 24 hours, and a sample was taken. The remainder of the mixture was maintained for another 6 hours at the same temperature and was then cooled, and a further sample was taken. Each of the samples was compressed at 2 tons per sq. in. pressure into a cylindrical mould of 1 diameter. Each pellet was then subjected to 16 temperature cycles between 0-50 C. and it was found that their initial diameters had increased by only 1.3% in each case. X-ray powder photographs of the hot stored mixtures after standing at ordinary temperature for some days showed that the ammonium nitrate had been stabilised in the III form.
• the pulverulent composition may be used as a constituent of compressed gas pressure producing charges containing say potassium chromate or ammonium bichromate as sensitiser of thermal decomposition as an added ingredient.
• Example IV 865 parts crystalline ammonium nitrate as used in Example I were ground together with 60 parts of potassium nitrate of a grist fine enough to pass a mesh B. S. S. screen and 75 parts anhydrous ammonium oxalate of the same grist as the potassium nitrate, until the mixture all passed a 100' mesh screen. These operations were conducted at room temperature. The ground mixture was then heated to 45 C. and maintained at that temperature for 18 hours. After cooling and standing for 4 to 5 days at 15-17 C. the X-ray diffraction pattern was found to be practically identical with that of a congealed fused mixture of ammonium nitrate and potassium nitrate in the proportions 90:10.
• the product may be used for all purposes similar to that indicated for the product of EX- ample III, which it resembles in enabling a compressed pellet of the gas pressure producing charge to be producedwhich will resist the usual disruptive effect of temperature cycling.
• a process for the production of a composition comprising ammonium nitrate and potassium nitrate which comprises mixing together ammonium nitrate and powered potassium nitrate and maintaining the mixture thus formed within a temperature range of about 32 C. and about 100 C. for a time long enough to ensure that the ammonium nitrate is stabilized substantially as modification III which is that modification having a rhombic crystal form, a specific ravity of 1.654 and stable between the transition points normally occurring at 32.3" and 84 C.
• ammonium nitrate used for mixing with the potassium nitrate is in the form of powder.
• ammonium nitrate used for mixing with the potassium nitrate is in the form of small granules.
• a process as claimed in claim 6 wherein the inorganic salt is selected from the group consisting of chromates and phosphates.
• water-soluble potassium salt is selected from the group consisting of potassium sulphate, potassium chloride, potassium dihydrogen orthophosphate, potassium oxalate, and potassium chromate.

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• Chemical & Material Sciences (AREA)
• Organic Chemistry (AREA)
• Inorganic Chemistry (AREA)
• Crystallography & Structural Chemistry (AREA)
• Life Sciences & Earth Sciences (AREA)
• Agronomy & Crop Science (AREA)
• Engineering & Computer Science (AREA)
• Materials Engineering (AREA)
• Fertilizers (AREA)

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Cited By (19)

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Citations (4)

• 0
  • NL NL707010000A patent/NL141516B/xx unknown
  • BE BE484524D patent/BE484524A/xx unknown
  • NL NL67443D patent/NL67443C/xx active
  • DE DENDAT906217D patent/DE906217C/de not_active Expired
• 1947
  • 1947-09-01 GB GB24093/47A patent/GB632754A/en not_active Expired
• 1948
  • 1948-07-15 US US38955A patent/US2590054A/en not_active Expired - Lifetime
  • 1948-07-19 FR FR969405D patent/FR969405A/fr not_active Expired
  • 1948-09-01 CH CH271123D patent/CH271123A/de unknown

Patent Citations (4)

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