Magnesium ammonium phosphate hexahydrate and monohydrate slurries
OwnerJ. Richard Green, Warren D. Wintersoninventors
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Abstract
A magnesium ammonium phosphate slurry and method of producing magnesium ammonium phosphate slurries. The method provides for obtaining a magnesium hydroxide supply having a small particle size of about 2 microns. Aqua ammonia and phosphoric acid are sequentially added while maintaining the temperature at below 110° F. The magnesium ammonium phosphate hexahydrate slurry formed has a small particle size of about 2 to 7 microns. The hexahydrate slurry may be converted to a monohydrate slurry having a particle size of less than about 8 microns by heating to the boiling point in the presence of excess water or heating to the boiling point while maintaining a very moderate hydrostatic pressure.
Claims18
A magnesium ammonium phosphate slurry, comprising:
- from about 21 wt. % to about 25 wt. % solid magnesium ammonium phosphate monohydrate particles, wherein at least about 85 wt. % of the particles have a size less than about 8 microns;
- and
- from about 75 wt. % to about 79 wt. % free water,
- where the slurry has a pH from about 6.8 to about 7.4.
A process for producing a magnesium ammonium phosphate monohydrate slurry, comprising the steps of:
- (a) obtaining a magnesium hydroxide slurry having magnesium hydroxide particles wherein at least about 55 wt. % of the particles have a size less than about 2 microns;
- (b) then adding ammonia;
- (c) while maintaining an excess of ammonia and cooling, adding phosphoric acid at a rate so as not to exceed a temperature of about 110° F.;
- (d) producing a magnesium ammonium phosphate hexahydrate slurry;
- (e) heating the magnesium ammonium phosphate hexahydrate slurry to its boiling point;
- wherein said monohydrate slurry has a slurry particle concentration of about 21 wt % to about 25 wt % and at least about 85 wt % of the particles have a size less than about 8 microns.
A magnesium ammonium monohydrate slurry produced by a process comprising the steps of:
- (a) obtaining a magnesium hydroxide slurry having magnesium hydroxide particles wherein at least about 55 wt. % of the particles have a size less than about 2 microns;
- (b) then adding ammonia;
- (c) while maintaining an excess of ammonia and cooling, adding phosphoric acid at a rate so as not to exceed a temperature of about 110° F.;
- (d) producing a magnesium ammonium phosphate hexahydrate slurry;
- (e) heating the magnesium ammonium phosphate hexahydrate slurry to its boiling point;
- wherein said monohydrate slurry has a slurry particle concentration of about 21 wt % to about 25 wt % and at least about 85 wt % of the particles have a size less than about 8 microns.
Dependencies are inferred from the claim text.