Core-Shell Urea Fertilizer Stabilization
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Solution Overview
Problem
The continuous use of urea fertilizers leads to nutrient imbalance, soil deterioration, and environmental issues due to rapid hydrolysis and nitrification, and existing solutions face challenges such as fouling and clogging in manufacturing processes and degradation of urease inhibitors.
Innovation Solution
A core-shell structured fertilizer particle with a core containing urea, a pH buffering agent, and a urease inhibitor, and a shell containing urea, which stabilizes the urease inhibitor and prevents fouling during manufacturing, and protects the urea from hydrolysis.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If binders such as Plaster of Paris and bleached wheat flour are used in the core composition, then the core can be made amenable to the extrusion process and withstand post-extrusion processes, but fouling and clogging of machines occurs during manufacturing
Solution Approach 1:
The patent removes the problematic binders (Plaster of Paris and bleached wheat flour) from the core composition entirely. The invention achieves extrusion processability without these binders by using alternative approaches such as controlling moisture content, using different filler materials, and optimizing the extrusion parameters, thereby eliminating the source of fouling and clogging while maintaining manufacturability.
Solution Approach 2:
The patent employs starch as a temporary binder that decomposes during the extrusion process. This starch is used only during manufacturing to enable shaping, and then it breaks down naturally, leaving no harmful residues that cause fouling or clogging in subsequent handling and storage processes.
2Ease of manufacture
If bleached wheat flour is used as a binder, then the core composition is amenable to extrusion, but risk for dust explosion is created
Solution Approach 1:
The patent eliminates bleached wheat flour from the formulation entirely, removing the source of dust explosion risk. Alternative binders or binder-free approaches are used instead, maintaining extrusion processability without the safety hazards associated with fine dust particles from wheat flour.
Solution Approach 2:
The patent uses starch as a temporary binder that decomposes during extrusion and is not present in the final product. This eliminates dust explosion risks associated with persistent organic dust particles, as the starch breaks down completely during the manufacturing process and leaves no combustible residue.
3Reliability
If urease inhibitor is added to the fertilizer, then nitrogen loss through ammonia volatilization is reduced, but degradation of the urease inhibitor occurs during manufacturing and storage
Solution Approach 1:
The patent places the urease inhibitor inside a core-shell structure where the core contains protective materials and the shell provides an additional barrier. This nested configuration protects the urease inhibitor from degradation during manufacturing and storage while maintaining its functionality in the soil, thereby extending its effective lifespan.
Solution Approach 2:
The patent introduces protective coatings and core materials as intermediaries between the urease inhibitor and the external environment. These intermediaries act as barriers that prevent direct exposure of the urease inhibitor to degrading conditions such as moisture, oxygen, and temperature fluctuations, thereby stabilizing it during manufacturing and storage.
4Strength
If urea is used in the core, then the core structure is stabilized and prevents crumbling, but rapid hydrolysis and nitrification occur leading to nitrogen loss
Solution Approach 1:
The patent places urea inside a core-shell structure where the shell acts as a protective barrier. This nested configuration allows the urea to maintain the structural stability of the core while the shell prevents rapid contact with soil microorganisms that cause hydrolysis and nitrification, thereby reducing nitrogen loss.
Solution Approach 2:
The patent introduces the shell as an intermediary layer between the urea and the soil environment. This shell acts as a barrier that controls the release of urea, preventing rapid hydrolysis and nitrification while still allowing controlled nutrient release to the plant, thus balancing structural stability with nitrogen conservation.
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 reduces nitrogen loss through ammonia volatilization and nitrification, enhances soil health, and allows for a more scalable and efficient production process by preventing fouling and degradation of urease inhibitors.
Implementation Method 1
a core containing urea, a pH buffering agent, and an urease inhibitor
Implementation Method 2
Urease inhibitors reduce the amount of urea hydrolyzed, which reduces the amount of nitrogen lost through ammonia volatilization
Implementation Method 3
Nitrification inhibitors reduce the rate of conversion of ammonium into nitrate, which also reduces the amount of nitrogen lost
Implementation Method 4
the core can help stabilize the urea containing shell (e.g., reduce hydrolyzation and/or nitrification of the urea in the shell)
Data Source
AI summary
Fertilizer particles containing a core and a shell is described. The core can contain urea, a pH buffering agent, and an urease inhibitor, and the shell can contain urea and can cover at least a portion of an outer surface of the core. The core can include 20 wt. % to 80 wt. % urea, based on the total weight of the core, and the shell can include 50 wt. % to 100 wt. % urea, based on the total weight of the core.