Silicon Microparticle Purification via Dilute Hydrogen Peroxide
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Solution Overview
Problem
Current methods for purifying silicon microparticles from cutting waste in the photovoltaic industry are inefficient due to limited ozone solubility, use of concentrated acids that pollute the environment, and inability to achieve required purification levels in dispersed aqueous mixtures, leading to reduced reuse potential and performance issues in semiconductor and photovoltaic applications.
Innovation Solution
A treatment method involving a dilute hydrogen peroxide solution to separate and purify silicon microparticles from contaminated slurry, followed by repeated rinsing and drying under an inert atmosphere to achieve high purity without using polluting substances, effectively reducing organic species and metal contaminants while minimizing silicon loss.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If concentrated acids are used to dissolve metal contaminants and remove silicon oxide, then purification effectiveness is improved, but environmental pollution and process cost increase
Solution Approach 1:
The patent changes the chemical parameters by replacing concentrated acids with dilute hydrogen peroxide solution. This parameter change maintains purification effectiveness through oxidative dissolution of metal contaminants and organic species, while eliminating the harmful environmental effects associated with concentrated acid usage. The hydrogen peroxide decomposes into water and oxygen, leaving no harmful residues.
Solution Approach 2:
The patent converts the harmful concentrated acids into a beneficial alternative by using hydrogen peroxide, which is environmentally friendly. The hydrogen peroxide serves multiple functions: oxidizing organic contaminants, dissolving metal particles, and can be safely disposed of by decomposition. This transforms a harmful substance into a beneficial one that achieves the same purification goals without environmental damage.
2Object-generated harmful factors
If ozone is used to remove organic species, then organic contamination is reduced, but purification efficiency is limited due to low solubility in water
Solution Approach 1:
The patent changes the oxidizing agent from ozone to hydrogen peroxide. Hydrogen peroxide has much higher solubility in water compared to ozone, which directly addresses the solubility limitation. This parameter change enables more efficient contact between the oxidizing agent and organic contaminants in the aqueous slurry, significantly improving purification efficiency while maintaining effective organic species removal.
3Object-generated harmful factors
If strong oxidants are used to oxidize silicon powder followed by organic solvent extraction, then organic species are removed, but silicon loss increases and environmental pollution occurs
Solution Approach 1:
The patent eliminates the need for organic solvents by using hydrogen peroxide oxidation followed by water-based processing. The hydrogen peroxide oxidizes organic species and metal contaminants, and the resulting mixture can be completely processed in aqueous media. This converts a harmful two-step process involving organic solvents into a benign single-phase aqueous process, preventing silicon loss during solvent extraction and eliminating environmental pollution from organic solvent disposal.
4Ease of manufacture
If successive treatments with strong bases and strong acids are applied, then cleaning effectiveness is improved, but purification level for dispersed microparticles remains insufficient
Solution Approach 1:
The patent changes from a multi-step process using strong bases and acids to a single-step treatment using dilute hydrogen peroxide. This parameter change simplifies the process while improving effectiveness for dispersed microparticles. The hydrogen peroxide solution can penetrate and treat individual microparticles uniformly in the slurry, achieving complete purification that successive batch treatments cannot accomplish.
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 method achieves a high level of purification, with less than 0.3% carbon and 100 ppm metal contaminants, and removes the silicon oxide layer, making the silicon microparticles suitable for reuse in various industries, including photovoltaics, while avoiding the use of harmful chemicals and minimizing environmental impact.
Implementation Method 1
adding a dilute hydrogen peroxide solution to the contaminated slurry, in order to form a first mixture
Implementation Method 2
hydrochloric acid to dissolve metal contaminants
Implementation Method 3
performing the filtration of the first mixture, in order to obtain, on the one hand, a first purified slurry and, on the other hand, a first liquid loaded with organic species and metal contaminants
Implementation Method 4
drying under an inert atmosphere in order to obtain purified silicon microparticles
Data Source
AI summary
A treatment method for purifying silicon microparticles contained in waste resulting from the cutting of ingots with a diamond wire comprises: a) providing a contaminated slurry, resulting from the waste, formed by an aqueous mixture comprising the silicon microparticles, organic species and metal contaminants; b) adding a dilute hydrogen peroxide solution to the contaminated slurry, in order to form a first mixture, and stirring the first mixture; c) solid/liquid separation of the first mixture in order to obtain, on the one hand, a first purified slurry and, on the other hand, a first liquid loaded with organic species and metal contaminants.