Urea Ammonium Nitrate Blend Stability via Polymer Mediator

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Solution Overview

Problem

Urea and ammonium nitrate are incompatible in solid blends due to the formation of hygroscopic double salts, leading to caking and mud formation, making it difficult to produce stable and safe high-concentration nitrogen fertilizers.

Innovation Solution

A solid blend of urea and ammonium nitrate particles is created by incorporating ammonium sulphate and a desiccant like magnesium nitrate, ensuring compatibility and preventing the formation of unwanted double salts, with particles of similar size and density to maintain stability and safety.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Quantity of substance

If urea and ammonium nitrate are blended in solid form, then high nitrogen concentration is achieved, but double salt formation occurs leading to caking and mud formation

Engineering Contradiction:
Improvenitrogen concentrationVSAvoidblend stability
Core Design Contradiction:
Quantity of substanceVSStability of the object's composition

Solution Approach 1:

A water-soluble polymer is introduced as an intermediary substance between urea and ammonium nitrate particles. The polymer absorbs the water released during double salt formation, preventing the liquid phase from causing caking and mud formation, thereby enabling stable high-concentration blends

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The invention changes the physical-chemical parameters of the blend by adding a polymer with specific molecular weight and hydroxyl number. This modifies the water binding capacity of the system, allowing the blend to maintain stability at high nitrogen concentrations that would otherwise be unstable

Inventive Principle:
Principle #35Parameter changes

2Quantity of substance

If urea and ammonium nitrate are blended, then nitrogen fertilizer efficiency is improved, but hygroscopicity increases causing water absorption from atmosphere

Engineering Contradiction:
Improvenitrogen contentVSAvoidhygroscopicity
Core Design Contradiction:
Quantity of substanceVSObject-affected harmful factors

Solution Approach 1:

The water-soluble polymer acts as a mediator that selectively binds water molecules released during double salt formation and water absorbed from the atmosphere, preventing these water molecules from causing caking and reducing overall hygroscopicity of the blend

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The invention creates a composite fertilizer blend consisting of urea particles, ammonium nitrate particles, and water-soluble polymer. This composite structure combines the high nitrogen content benefits of both fertilizers while the polymer component counteracts the hygroscopicity issue

Inventive Principle:
Principle #40Composite materials

3Stability of the object's composition

If double salt formation is prevented, then blend stability is improved, but manufacturing complexity increases

Engineering Contradiction:
Improveblend stabilityVSAvoidmanufacturing process complexity
Core Design Contradiction:
Stability of the object's compositionVSDevice complexity

Solution Approach 1:

The water-soluble polymer is added during the existing granulation or blending process, requiring minimal equipment modification. The polymer is distributed throughout the blend using standard mixing equipment, maintaining manufacturing simplicity while achieving blend stability

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The manufacturing process parameters are adjusted by incorporating the polymer at specific stages (granulation or blending) with controlled amounts based on the fertilizer composition. These parameter changes are integrated into existing processes without requiring complex new equipment

Inventive Principle:
Principle #35Parameter changes

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

The solution allows for the production of a stable, safe, and highly concentrated nitrogen fertilizer that is resistant to caking and misuse, with limited adaptations to existing production processes, ensuring safety and economic viability.

Implementation Method 1

The ammonium nitrate based particles comprise a salt that is able to bind crystallisation water, selected from magnesium nitrate, magnesium sulphate, aluminium sulphate or mixtures thereof

Methodology Applied
Scientific EffectDesiccant material: Desiccant Material

Implementation Method 2

The urea based particles contain ammonium sulphate, either in the mass of the particle (for instance distributed throughout the particle) or as an external layer

Methodology Applied
Scientific EffectSolid solution strengthening: Solid Solution Strengthening

Data Source

PatentEP2890664B1Safe blends of ammonium nitrate (AN) with urea, or of an an-comprising product with a urea-comprising product
Publication Date: 2018.01.31 YARA INTERNATIONAL ASA

AI summary

The present invention relates to a solid blend of urea based and ammonium nitrate based particles, the blend comprising ammonium nitrate based particles with salts able to bind crystallization water and urea particles with ammonium sulphate.