Continuous process for crystallizing nitroguanidine
AssigneeThe United States of America as represented by the Secretary of the Navy
InventorsSteven L. Collignon, Kerry L. Wagaman
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Abstract
A continuous process for forming spheroidal high bulk density nitroguanid crystals from an aqueous solution of nitroguanidine which contains methylcellulose and partially hydrolyzed poly(vinyl alcohol) as crystal habit modifiers. A saturated aqueous solution of nitroguanidine is formed at a temperature T.sub.1 where 70.degree. C..ltoreq.T.sub.1 .ltoreq.100.degree. C. and crystallization occurs at a lower temperature T.sub.2 where 20.degree. C..ltoreq.T.sub.1 -T.sub.2 .ltoreq.50.degree. C.
Claims8
A continuous process for recrystallizing nitroguanidine comprising the following steps in order:
- (1) forming a saturated aqueous nitroguanidine solution at a constant temperature T.sub.1 which is in the range of from about 70.degree. C. to about 100.degree. C. wherein the solution also contains from 0.5 to 2.0 weight percent of methylcellulose and from 0.5 to 2.0 weight percent of a partially hydrolyzed poly(vinyl alcohol);
- (2) feeding the solution formed in step (1) into a crystallizer containing a saturated aqueous solution of nitroguanidine which is maintained at a constant temperature of T.sub.2 wherein 20.degree. C..ltoreq.T.sub.1 -T.sub.2 .ltoreq.50.degree. C. and wherein the methylcellulose and partially hydrolyzed poly(vinyl alcohol) concentrations are the same as in the feed solution;
- (3) separating the product spheroidal or ovate nitroguanidine crystals from the supernatant aqueous nitroguanidine solution;
- and
- (4) recycling the separated supernatant aqueous nitroguanidine solution to be used again in step (1).
The process of claim wherein the solution in the crystalizer in step (2) is continuously agitated.
Dependencies are inferred from the claim text.