UREA-AMMONIUM POLYPHOSPHATE PRODUCTION

• US 3,825,414 A
• Filed: 12/10/1973
• Issued: 07/23/1974
• Est. Priority Date: 11/29/1971
• Status: Expired due to Term

• Current Assignee: Robert D. Mitchell, Robert G. Lee
• Original Assignee: Robert D. Mitchell, Robert G. Lee
• Inventors: Lee, Robert G., Mitchell, Robert D.
• Primary Examiner(s): Zaharna, Samih N.
• Assistant Examiner(s): Barnes, Richard
• Application Number:
  US05/423,419
• Time in Patent Office: 225 Days
• Field of Search: 71/29,34-36,64DA
• US Class Current: 71/29
• CPC Class Codes: C05B 13/06 Alkali and alkaline earth meta- or polyphosphate fertilisers
• CPC Class Codes: C05B 19/00 Granulation or pelletisation of phosphatic fertilisers, other than slag granulating apparatus B01J2/00; granulating slag C04B
• CPC Class Codes: C05C 9/005 Post-treatment
• CPC Class Codes: C05G 1/00 Mixtures of fertilisers belonging individually to different subclasses of C05

Abstract

Pugmill granulation process for the production of fertilizers containing urea and ammonium polyphosphate. Concentrated urea solution is sprayed onto recycled solids in the pugmill followed by molten ammonium polyphosphate. The melt is fed to the pugmill at a minimum of 12 inches downstream from the urea to prevent hydrolysis of the urea which results in foaming and gas evolution. The product from the pugmill is essentially anhydrous, and no further drying is required. Other fertilizer materials such as ammonium sulfate, potassium chloride, or micronutrient sources may be incorporated by adding them to the pugmill during granulation.

Claims

2. maintaining the temperature of the material discharged from said pugmill in the range from about 130*F to about 250*F, and discharging therefrom the resulting solid urea ammonium polyphosphate mixture into cooling means;

and

3. passing the resulting cooled mixture of urea and ammonium polyphosphate over screens to separate the oversize material and the undersize material from the product-size material;

crushing said oversize material and combining with said undersize material for recycle to said step (1) supra at a recycle rate expressed as pounds of recycle fines;

pound of product in the ratio of about 0.5 to about 10 and introduced into said pugmill in step (1) supra at a temperature in the range from about 70* to about 180*F.