Solid Urea Leaching for Low-Biuret Purification
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Solution Overview
Problem
Existing urea production processes struggle to achieve low biuret content efficiently, particularly in evaporation-based concentration sections, failing to meet stringent quality requirements for applications like fertilizer and diesel exhaust fluid, while crystallization-based methods are costly and resource-intensive.
Innovation Solution
A leaching process using an aqueous urea solution to remove biuret from solid urea, followed by biuret crystallization and recycling, allowing for the production of low-biuret urea without requiring expensive crystallization infrastructure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If evaporation-based concentration is used, then the process is simpler and more commonly applied, but biuret content increases due to high temperature processing
Solution Approach 1:
The patent extracts biuret from the urea product by introducing a leaching solution that selectively dissolves biuret while leaving urea intact. This separation step removes the harmful impurity formed during evaporation without requiring complete avoidance of the evaporation process itself.
Solution Approach 2:
The patent changes the chemical environment by introducing a leaching solution with specific composition (water and optionally urea or alcohol) that creates selective solubility conditions. Biuret dissolves in this solution while urea remains solid, enabling separation based on differential solubility parameters.
2Manufacturing precision
If crystallization-based concentration is used, then biuret content is reduced to below 0.9%, but the process becomes expensive requiring melter installation
Solution Approach 1:
The patent replaces expensive, complex crystallization-melting equipment with a simpler leaching system using readily available leaching solutions (water, urea solution, or alcohol). The leaching process achieves comparable biuret removal without requiring urea melters or complex crystal handling infrastructure.
Solution Approach 2:
The patent introduces a leaching solution as an intermediary substance that facilitates biuret removal. This mediator selectively interacts with biuret to dissolve and separate it from urea, replacing the need for direct thermal-crystallization-melting cycles.
3Productivity
If high temperature evaporation is used to concentrate urea solution, then water is efficiently removed, but biuret is formed as an unwanted by-product
Solution Approach 1:
The patent accepts that biuret will form during evaporation but converts this harmful effect into a benefit by subsequently using the biuret-containing leaching solution for controlled biuret production in cattle feed applications. The unwanted by-product becomes a valuable secondary product.
Solution Approach 2:
The patent extracts biuret from the urea product through leaching, separating the harmful impurity from the desired product. This allows the evaporation step to proceed efficiently for concentration while the biuret removal step cleans up the unwanted by-product.
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
Achieves low-biuret urea comparable to crystallization methods, while being cost-effective and adaptable to existing evaporation-based urea plants, with the added benefit of producing high-biuret urea as a valuable by-product.
Implementation Method 1
biuret contained in the solid urea is transferred to the solution
Implementation Method 2
leaching the solid urea with a leaching solution which is an aqueous solution of urea and is saturated with urea, wherein biuret contained in the solid urea is transferred to the solution
Data Source
AI summary
A process for removing biuret for solid urea (UR), wherein the solid urea is in a granular or powder form, the process including leaching the solid urea with a leaching solution (LS) which is a urea saturated aqueous solution, wherein biuret contained in the solid urea is transferred to said leaching solution during the leaching process, obtaining a purified solid urea.