Phase-stabilization of ammonium nitrate by zinc diammine complexes

• US 5,071,630 A
• Filed: 06/20/1990
• Issued: 12/10/1991
• Est. Priority Date: 06/20/1990
• Status: Expired due to Fees

• Current Assignee: John H. Wickman
• Original Assignee: John H. Wickman
• Inventors: Oberth, Adolf E.
• Primary Examiner(s): Langel, Wayne A.
• Application Number:
  US07/540,590
• Time in Patent Office: 538 Days
• Field of Search: 423/266, 423/396
• US Class Current: 423/266
• CPC Class Codes: C01C 1/18 Nitrates of ammonium
• CPC Class Codes: C01G 9/00 Compounds of zinc
• CPC Class Codes: C06B 31/28 the salt being ammonium nitrate

Abstract

A phase-stable, oxidizer-grade zinc diammine complex stabilized ammonium nitrate that retains its phase-stability, has a minimum hygroscopicity and cure interference, is prepared by dissolving an anhydrous zinc diammine complex, which may be either the sulfate, perchlorate or nitrate, in dry molten ammonium nitrate. The complex is best prepared in a separate step by melting a 3/1 molar mixture of ammonium nitrate with zinc oxide which produces the zinc diammine dinitrate complex contaminated with the water of the reaction. The melt is dried by driving off the water. First by simple boiling, and the final traces by means of purging with dry air or nitrogen gas. The ammonia lost in this drying operation is exactly replenished by purging with anhydrous ammonia gas. The sulfate complex is obtained by co-dissolving an essentially stoichiometric quantity of ammonium sulfate in either the melt of the complex or the bulk of the molten ammonium nitrate. The perchlorate complex is prepared similarly by co-dissolving a stoichiometric quantity of ammonium perchlorate in the molten ammonium nitrate.

Claims

1. A method of preparing zinc-phase-stabilized ammonium nitrate having an improved retention of phase-stability, reduced hygroscopicity, and minimal cure interference in polyurethane cure-systems, consisting of

a) reacting zinc oxide by co-melting it with 3 to 4 times the molar quantity of ammonium nitrate,

b) removing the water generated in said reaction by purging the melt with dry inert gas, followed by

c) adjusting the ammonia content of the melt to 200 to 204 mole per cent with respect to the applied zinc oxide by passing dry ammonia gas into said melt, and

d) dissolving said melt in dry, molten ammonium nitrate to give a zinc metal concentration of 1 to 4 per cent, followed by

e) solidification and granulation of the product.

2. The method of claim 1, where 0.5 to 1.5 times the molar quantity of ammonium sulfate per mol zinc oxide is added to said mixture of ammonium nitrate and zinc oxide.

3. The method of claim 2, where 1 to 3 times the molar quantity of ammonium perchlorate per mole zinc oxide replaces the ammonium sulfate.

4. A process of making zinc-phase-stabilized ammonium nitrate having an improved retention of phase-stability, reduced hygroscopicity, and minimal cure interference in polyurethane cure-systems, comprising the steps of:

a) Dissolving 1.5 to 5 per cent zinc oxide in molten ammonium nitrate, and

b) removing the water of reaction plus additional moisture that may be present in the ammonium nitrate melt by purging with an inert gas, folowed by

c) adjusting the ammonia level in said melt with anhydrous, ammonia gas to 2.0 to 2.04 times the molar quantity of the applied zinc oxide, and

d) converting said melt into a solid, granular product.

5. A method according to claim 4, wherein an additional 0.5 to 1.5 times the molar quantity of ammonium sulfate per mol of the applied zinc oxide is co-dissolved in said melt.

6. A method according to claim 5, where the ammonium sulfate is replaced by 1 to 3 times the molar quantity of ammonium perchlorate per mol zinc oxide.