Soluble-Insoluble Phosphor Mixtures for Cleaner Luminophore Recovery

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Solution Overview

Problem

Existing phosphor recycling processes are complex and often result in hazardous waste due to the use of caustic chemicals and difficult-to-dispose chemicals, making it challenging to recover phosphors from mercury-containing mixtures for reuse in new lamps.

Innovation Solution

A phosphor mixture with a soluble and insoluble component, where the soluble phosphor has a solubility at least 100 times greater than the insoluble phosphor in a polar solvent, allowing for easy separation and recovery without caustic chemicals, using a host lattice and activator combination that enhances recyclability and emission spectrum control.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Loss of substance

If complex chemical separation processes are used to recover phosphors from mercury-containing mixtures, then phosphor recovery is achieved, but the process becomes environmentally harmful and generates hazardous waste

Engineering Contradiction:

Improvephosphor recoveryVSAvoidhazardous waste

Core Design Contradiction:

Loss of substanceVSObject-generated harmful factors

Solution Approach 1:

The patent changes the chemical parameters of the phosphor mixture by incorporating water-soluble phosphors (such as calcium halide, strontium halide, or barium halide doped with activators) that can be selectively dissolved in aqueous solutions. This parameter change enables separation from insoluble phosphors and mercury through simple filtration, eliminating the need for complex chemical treatments and hazardous waste generation.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent converts the previously problematic mercury-containing phosphor mixture into a beneficial separation system. By incorporating water-soluble phosphors, the mercury can be easily separated along with the soluble phosphors through aqueous dissolution and filtration, transforming a hazardous waste problem into a simple physical separation process that recovers both phosphors and mercury.

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

2Loss of substance

If multiple separation steps are used to isolate rare earth elements from phosphor mixtures, then phosphor recovery is achieved, but the process complexity increases

Engineering Contradiction:

Improvephosphor recoveryVSAvoidprocess complexity

Core Design Contradiction:

Loss of substanceVSDevice complexity

Solution Approach 1:

The patent fundamentally changes the separation parameter from complex chemical digestion and multiple extraction steps to a simple aqueous solubility-based separation. The water-soluble phosphors dissolve in water while insoluble phosphors and mercury remain undissolved, allowing separation through simple filtration without requiring multiple chemical treatment steps.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent segments the phosphor mixture into three distinct fractions based on solubility: water-soluble phosphors (calcium, strontium, or barium halides), water-insoluble phosphors (rare earth phosphors), and mercury. This segmentation enables each component to be recovered separately through a single filtration step, dramatically simplifying the overall process.

Inventive Principle:

Principle #1Segmentation

3Loss of substance

If corrosive chemicals are used to extract phosphors from phosphor mixtures, then phosphor recovery is achieved, but environmental friendliness deteriorates

Engineering Contradiction:

Improvephosphor recoveryVSAvoidenvironmental friendliness

Core Design Contradiction:

Loss of substanceVSObject-affected harmful factors

Solution Approach 1:

The patent changes the chemical parameter of the extraction medium from corrosive acids and bases to water. The water-soluble phosphors (calcium halide, strontium halide, or barium halide) can be selectively dissolved in water, providing an environmentally friendly separation method that eliminates the need for corrosive chemicals while maintaining effective phosphor recovery.

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

Enables efficient and environmentally friendly recovery of phosphors with high purity, suitable for reuse in new phosphor mixtures and lamps, independent of microstructure and agglomeration, using inexpensive alkali metal and alkaline earth metal halides as host lattices and transition or rare earth metals as activators.

Implementation Method 1

the solubility of the at least one soluble phosphor is at least 100 times greater than the solubility of the at least one insoluble phosphor in a polar-protic or a polar-aprotic solvent

Methodology Applied

Scientific EffectSolvation: Solvation

Implementation Method 2

Separating the dispersion into two fractions consisting of a liquid phase containing at least one soluble phosphor and a solid phase containing at least one insoluble phosphor by a mechanical separation process

Methodology Applied

Scientific EffectCentrifugal separation: Centrifugal Separation

Data Source

PatentEP3545050B1Luminophore mixture composed of soluble and insoluble luminophores, and process for reclaiming the luminophores

Publication Date: 2024.01.03 FRAUNHOFER GESELLSCHAFT ZUR FORDERUNG DER ANGEWANDTEN FORSCHUNG EV

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AI summary

The invention relates to a luminophore mixture containing at least one soluble luminophore and at least one insoluble luminophore as well as to a process that allows the at least one soluble luminophore or the at least one insoluble luminophore to be reclaimed. The invention also relates to a lamp comprising a luminescent layer that contains the luminophore mixture.