Process for preparing a fertiliser

Patent metadata

Field	Value
Publication number	US-10464854-B2
Application number	US-201414901748-A
Country	US
Kind code	B2
Filing date	Jul 2, 2014
Priority date	Jul 3, 2013
Publication date	Nov 5, 2019
Grant date	Nov 5, 2019

Abstract

A process for preparing a micronutrient-enriched phosphate-based fertilizer is disclosed. An aqueous fertilizer mixture comprising phosphoric acid and/or phosphate rock is prepared and optionally granulated in granulator unit. The pH of the fertilizer mixture is measured and controlled such that the pH is maintained within a predefined range.

First claim

That which is claimed is:

1. A process for preparing a zinc-enriched phosphate-based fertilizer comprising steps of:
mixing phosphoric acid, having a strength in the range of from 5 to 60 wt % P 2 O 5 , ammonia, zinc oxide, and elemental sulfur to yield an aqueous fertilizer mixture having a pH;
controlling the pH of the aqueous fertilizer mixture within a predefined range of from 3.5 to 4.0;
granulating the aqueous fertilizer mixture in a granulator unit to yield fertilizer granules; and
drying the fertilizer granules; and
wherein a water-soluble portion of zinc from the zinc oxide is at least 50% present in the aqueous fertilizer mixture when the ammonia:phosphoric acid (N:P) molar ratio of the aqueous fertilizer mixture ranges from about 0.90 to about 1.00.

2. A process according to claim 1 , wherein the phosphate-based fertilizer is an ammonium phosphate fertilizer.

3. A process as recited in claim 1 , wherein the amount of elemental sulfur mixed in the aqueous fertilizer mixture is in the range of from 1 to 12 wt %, based on the total weight of aqueous fertilizer mixture.

4. A process as recited in claim 1 , wherein the amount of zinc oxide mixed in the aqueous fertilizer mixture is in the range of from 0.05 to 5 wt %, based on the total weight of the aqueous fertilizer mixture.

5. A process as recited in claim 1 , further comprising: sorting the dried fertilizer granules to yield oversized granules, undersized granules and dried fertilizer granules having a mean average diameter in the range of from 1.5 to 5.0 mm.

6. A process as recited in claim 1 , wherein the amount of zinc oxide mixed in the aqueous fertilizer mixture is in the range of from 0.5 to 2 wt %, based on the total weight of aqueous fertilizer mixture.

7. A process as recited in claim 1 , wherein the controlling step includes varying amounts of phosphoric acid and ammonia in the aqueous fertilizer mixture to provide for the predefined range of the pH of the aqueous fertilizer.

8. A process as recited in claim 7 , wherein the pH is further controlled by the controlling step by adding an amount of sulfuric acid in the range of from 1 to 5 wt %, based on the total weight of the aqueous fertilizer mixture.

Assignees

• Shell Oil Co

Inventors

• Allais Cyrille Paul
• Garcia Martinez Rafael Alberto
• Hutter Klaas Jan
• Ingoldsby Charles James
• O'Brien Jason Trevor
• Moreira Tomaz Carlos

Classifications

• C05B13/06

  Alkali and alkaline earth meta- or polyphosphate fertilisers · CPC title

• C05B1/04

  Double-superphosphate; Triple-superphosphate; Other fertilisers based essentially on monocalcium phosphate · CPC title

• C05D9/02

  containing trace elements · CPC title

• C05B7/00

  Fertilisers based essentially on alkali or ammonium orthophosphates (C05B11/00 takes precedence) · CPC title

• C05B19/00

  Granulation or pelletisation of phosphatic fertilisers, other than slag (granulating apparatus B01J2/00; granulating slag C04B) · CPC title