Urea Calcium Sulfate Coating for Caking-Resistant Fertilizer
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Solution Overview
Problem
Existing urea-based fertilizers face issues with stability, leading to caking and rapid hydrolysis, which reduces nitrogen availability for plants and contributes to environmental pollution, while high calcium sulfate content limits other nutrient amounts.
Innovation Solution
Coating urea granules with a urea calcium sulfate (UCS) adduct to stabilize urea, forming a shell that maintains nitrogen content and reduces caking, with optional additives like urease and nitrification inhibitors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If urea is blended with other fertilizers to provide multiple nutrients, then nutrient diversity is improved, but stability deteriorates causing wet caking and sticky mass formation
Solution Approach 1:
The fertilizer is segmented into a core component (urea granules) and a coating layer (UCS adduct). This segmentation allows the urea to be physically separated from other fertilizer components that would otherwise cause caking, while still providing multiple nutrients through the coating. The core-shell structure resolves the contradiction by isolating the unstable urea from direct contact with other fertilizers.
Solution Approach 2:
The UCS adduct coating acts as an intermediary layer between the urea core and the external environment. This intermediate coating prevents direct interaction between urea and other fertilizer components, thereby preventing caking while maintaining nutrient availability. The coating mediates between the need for nutrient diversity and the need for stability.
2Stability of the object's composition
If high amounts of calcium sulfate are used to stabilize nitrogen fertilizers, then urea stability is improved, but nitrogen content deteriorates due to limited amounts of other nutrients
Solution Approach 1:
The invention changes the chemical parameter of the coating material from pure calcium sulfate to a urea-calcium sulfate adduct with specific stoichiometry (CaSO4·4CO(NH2)2). This parameter change allows the coating to provide both stability (through calcium sulfate) and nitrogen content (through incorporated urea molecules), resolving the contradiction between stability and nitrogen quantity.
Solution Approach 2:
The UCS adduct is a composite material combining calcium sulfate and urea in a specific ratio. This composite structure allows the coating to simultaneously provide the stabilizing effect of calcium sulfate and the nitrogen content of urea, overcoming the limitation of using pure calcium sulfate which would dilute the nitrogen content.
3Speed
If urea undergoes rapid hydrolysis in soil, then nitrogen release speed is improved, but nitrogen availability deteriorates and environmental harm increases
Solution Approach 1:
The UCS adduct coating is applied to urea granules before application to soil, creating a pre-formed protective barrier. This preliminary action prevents rapid hydrolysis upon contact with soil moisture, controlling the rate of nitrogen release and preventing premature loss of nitrogen to the environment while ensuring sustained availability.
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 UCS-coated urea granules enhance nitrogen uptake and stability, reducing losses and maintaining soil health while minimizing environmental impact.
Implementation Method 1
urea can undergo rapid hydrolysis in soil by soil bacteria. Rapid hydrolysis of urea can reduce amount of nitrogen available for plants
Implementation Method 2
coating urea with a UCS adduct can stabilize urea. Efficient nitrogen uptake by plants and relatively lower urea nitrogen losses are achieved by using the UCS coated urea granules
Data Source
Figure 1A~1B
Figure 2~3
Figure 4A~4B
AI summary
Disclosed is a fertilizer granule containing a core containing at least 90 wt. % of urea, and a shell containing a urea calcium sulfate (UCS) adduct, where the shell covers at least a portion of an outer surface of the core, and blends of the fertilizer granules with other fertilizers. Methods of making and using the fertilizer granule and the blends are also disclosed.