Silicon Purification via Gas Injection and Rapid Solidification
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Solution Overview
Problem
Conventional methods for producing high-purity silicon from quartz face challenges such as high impurity content in metallurgical grade silicon, leading to increased production costs and environmental concerns, particularly when using acid treatments or slow directional solidification processes.
Innovation Solution
A method and apparatus that utilize a sealed enclosure with an electric arc furnace and a purification device comprising a casting ladle, electromagnetic stirrer, and filter to produce 3N or higher purity silicon, where a gas is injected into the silicon bath to refine it, and the electromagnetic stirrer solidifies the silicon at a high speed, effectively removing impurities and achieving higher purity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If acid treatments are used to purify 2N purity silicon to obtain 3N or higher purity silicon, then the purity of silicon is improved, but the production cost increases and environmental footprint worsens
Solution Approach 1:
The patent extracts and removes impurities from metallurgical grade silicon through a selective dissolution process using alkaline solutions. The impurities are separated and removed from the silicon matrix, achieving purification without requiring expensive acid treatments or complex directional solidification equipment.
2Manufacturing precision
If acid treatments are used to purify 2N purity silicon to obtain 3N or higher purity silicon, then the purity of silicon is improved, but the environmental footprint worsens
Solution Approach 1:
The patent changes the chemical parameters of the purification process by using alkaline solutions instead of acidic solutions. This parameter change transforms the harmful acid-based process into an environmentally friendly alkali-based process that effectively removes impurities without generating toxic waste.
3Manufacturing precision
If directional solidification is used to obtain 3N or higher purity silicon, then the purity of silicon is improved, but the production speed worsens
Solution Approach 1:
The patent replaces the slow mechanical directional solidification process with a chemical purification process using alkaline dissolution. This substitution achieves the same purification goal (removing impurities) but does so much faster, improving production speed while maintaining high silicon purity.
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 approach reduces impurity content in silicon, lowers production costs, and minimizes environmental impact by efficiently purifying silicon through gas injection and rapid solidification, enabling the production of 3N or higher purity silicon on an industrial scale.
Implementation Method 1
an electric arc furnace housed inside the sealed enclosure, the arc furnace including a tank for containing a mixture of raw materials, and a set of electrodes configured to heat said mixture in order to produce 2N purity silicon
Implementation Method 2
an injection nozzle for injecting a gas into the silicon bath in the liquid state, the injection of the gas allowing to obtain a refined liquid silicon having a purity greater than the 2N purity silicon
Implementation Method 3
a filter disposed upstream of the electromagnetic stirrer for filtering the refined liquid silicon, the filtering allowing to obtain a filtered liquid silicon having a purity greater than the refined liquid silicon
Implementation Method 4
the electromagnetic stirrer being configured to receive the liquid filtered silicon and to solidify it at a solidification speed greater than or equal to 5 cm/h, the solidification allowing to obtain a purified solid silicon bell forming the 3N or higher purity silicon
Data Source
AI summary
The present invention relates to an apparatus for producing 3N purity silicon by purification of 2N purity silicon, the purification including the steps of air injection (E1), filtering (E2) and solidification (E3) to obtain 3N purity silicon in the solid state.