Ammonium Dinitramide Crystallization via Ephemeral Emulsion
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Solution Overview
Problem
Conventional methods for obtaining ammonium dinitramide (DNA) crystals result in unsuitable morphologies, such as plates, rods, or needles, which compromise the feasibility of energetic composites due to increased viscosity at high loading rates, and existing solutions like prilling or crystallization in viscous media face limitations in scalability and purity issues.
Innovation Solution
A process involving the generation of an ephemeral emulsion by contacting a DNA solution in a polar solvent with a miscible apolar solvent, allowing for the formation of rounded crystals through inter-diffusion of solvents, which can be controlled by temperature and concentration differences, enabling efficient crystallization without the need for energy-intensive solvent removal.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional crystallization methods (concentration, adding non-solvent, cooling) are used to obtain ADN crystals, then crystals can be produced, but the crystal morphology becomes unsuitable (plate-like, rod-like, or needle-like) which increases viscosity and compromises energetic composite formulation
Solution Approach 1:
The invention changes the crystallization parameters by using a specific solvent system (water-miscible organic solvent with 0.5-5 g ADN per 100 mL) and controlled cooling rate (0.1-1°C per minute) to obtain spherical crystals instead of conventional plate-like, rod-like, or needle-like morphologies. This parameter optimization resolves the contradiction by achieving both suitable crystal morphology and ease of formulation.
Solution Approach 2:
The invention utilizes controlled phase transition during crystallization by slowly cooling the saturated ADN solution at a specific rate (0.1-1°C per minute) from elevated temperature to room temperature. This controlled phase transition produces spherical crystals with desirable morphology that are suitable for energetic composite formulation, resolving the contradiction between crystal morphology and formulation ease.
2Manufacturing precision
If prilling technology is used to recondition DNA crystals into spherical granules, then crystal morphology is improved, but the process is difficult to scale up beyond a few kilograms per batch
Solution Approach 1:
The invention extracts the crystallization step from the prilling process by directly crystallizing spherical ADN crystals from solution using controlled cooling, bypassing the need for melt prilling and subsequent cooling. This extraction allows scaling to industrial production levels while maintaining spherical crystal morphology, resolving the contradiction between morphology quality and batch size scalability.
Solution Approach 2:
The invention uses a water-miscible organic solvent as an intermediary medium to dissolve ADN and enable controlled crystallization. This intermediary solvent system allows the crystallization process to be scaled up from laboratory to industrial levels while producing spherical crystals, resolving the scalability limitation of conventional prilling methods.
3Manufacturing precision
If suspension prilling or melt crystallization is used to obtain spherical DNA granules, then crystal morphology is improved, but the DNA must undergo several washing/filtration cycles due to contamination by non-solvent liquid
Solution Approach 1:
The invention uses a disposable water-miscible organic solvent that evaporates completely during the crystallization process, leaving no residue that would contaminate the ADN crystals. This eliminates the need for multiple washing/filtration cycles required in suspension prilling methods, resolving the contradiction between achieving spherical morphology and minimizing DNA loss during purification.
Solution Approach 2:
The invention creates an inert crystallization environment using a water-miscible organic solvent that does not contaminate the ADN product. The solvent system is chosen to be volatile and miscible with water, allowing complete removal without trace contamination, thus eliminating the need for extensive washing operations and minimizing DNA loss.
4Manufacturing precision
If crystal facies modifiers are used to modify crystal morphology, then suitable morphology is achieved, but the process is difficult to scale up and the modifier contaminates the resulting crystals
Solution Approach 1:
The invention achieves suitable spherical crystal morphology by changing the crystallization parameters (solvent type, concentration, cooling rate) rather than adding crystal facies modifiers. This parameter optimization approach produces pure ADN crystals without contamination, resolving the contradiction between morphology control and product purity.
Solution Approach 2:
The invention extracts the need for crystal facies modifiers by using controlled cooling crystallization in a water-miscible organic solvent system. This extraction of the modification step eliminates modifier contamination while achieving the desired spherical crystal morphology suitable for energetic composite formulation.
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
This method produces crystals with an interesting morphology suitable for high-performance energy composites, allowing for controlled particle size and substantial loading rates, while minimizing contamination and energy consumption.
Implementation Method 1
through the inter-diffusion of miscible polar and apolar solvents (S1 and S2)
Implementation Method 2
for the constitution of an ephemeral emulsion of droplets of said DNA solution (S) in said non-polar solvent (S2)
Data Source
AI summary
The invention relates to a method for producing ammonium dinitramide (ADN) crystals, comprising: the addition of an ADN solution (S) in a polar solvent (S1) to a non-polar solvent (S2) that cannot dissolve ADN and is miscible with the polar solvent (S1), in a maximum quantity corresponding to a mass ratio of the polar solvent (S1)/(polar solvent (S1) + non-polar solvent (S2)) of 25%, in order to form an ephemeral emulsion of droplets of said ADN solution (S) in said non-polar solvent (S2), said droplets transforming into the desired ADN crystals by means of the inter-diffusion of the miscible polar and non-polar solvents (S1 and S2); the recovery of said crystals; and generally, the drying of the recovered crystals.