Viscosity control of particle formation by adjusting agitation speed

1. A method of calculating and controlling the viscosity of a shear-thinnable fluid stream at a particle-forming section of a dispersion device by:

a) providing a measured static head of shear-thinnable fluid within the dispersion device;

b) providing a pressurized blanket of inert gas over the fluid at a measured gas pressure;

c) mechanically agitating the fluid in the dispersion device at a measured agitation speed;

d) calculating the viscosity of the agitated fluid; and

e) controlling the viscosity at the particle-forming section by adjusting the agitation speed.

2. The method of claim 1 wherein the dispersion device is a prill head and the particles are prills.

3. The method of claim 1 wherein the shear-thinnable liquid is formed by providing a molten first component, mixing at least one second component with the first component, and reacting the components at a temperature and for a time sufficient to form a mixture having a viscosity which decreases with increasing shear rate.

4. The method of claim 3 wherein the shear-thinnable mixture is a melt slurry.

5. The method of claim 1 wherein the shear-thinnable liquid comprises no more than about 2 weight percent water.

6. The method of claim 1 wherein the dispersion device is a spray nozzle.

7. The method of claim 6 wherein the liquid is a slurry.

8. A method of calculating and controlling the viscosity of a shear-thinnable fluid stream at a prill head by:

a) providing a measured static head of shear-thinnable liquid within the prill head;

b) providing a pressurized blanket of inert gas over the liquid at a measured gas pressure;

c) mechanically agitating the liquid in the prill head at a measured agitation speed;

d) calculating the viscosity of the agitated liquid; and

e) controlling the viscosity of the liquid at the prill head by adjusting the agitation speed.

9. The method of claim 8 wherein the shear-thinnable liquid is formed by providing a molten first component, mixing at least one second component with the first component, and reacting the components at a temperature and for a time sufficient to form a mixture having a viscosity which decreases with increasing shear rate.

10. The method of claim 9 wherein the shear-thinnable mixture is agitated in the prill head under conditions such that the entire liquid volume in the prill head is swept by the agitator to shear-thin the shear-thinnable mixture.

11. The method of claim 9 wherein the shear-thinnable mixture is a melt slurry.

12. The method of claim 9 wherein the first component is ammonium nitrate and the second component is ammonium sulfate.

13. The method of claim 9 wherein the shear-thinnable mixture further comprises micronutrients.

14. The method of claim 9 wherein the shear-thinnable mixture comprises no more than about 2 weight percent water.

15. The method of claim 8 wherein the prill head is one selected from the group comprising a rotating bucket with a stationary blade, a stationary bucket with rotating scrappers and blades, and an agitated pressurized nozzle assembly.

16. The method of claim 8 wherein the prill head is wiped with surface-wiping blades.

17. A method of calculating and controlling the viscosity of a shear-thinnable fluid stream in a spray nozzle by:

a) providing a measured static head of shear-thinnable fluid within the nozzle;

b) providing a pressurized blanket of inert gas over the fluid at a measured gas pressure;

c) mechanically agitating the fluid in the nozzle at a measured agitation speed;

d) calculating the viscosity of the agitated fluid; and

e) controlling the viscosity of the fluid by adjusting the agitation speed.

18. The method of claim 17 wherein the liquid is a slurry.

19. The method of claim 17 wherein the nozzle is one selected from the group comprising a rotating bucket with a stationary blade, a stationary bucket with rotating scrappers and blades, and an agitated pressurized nozzle assembly.