Silicon Extraction from a Diamond Wire Saw Silicon Slurry with Flotation and the Flotation Interface Behavior

Area of Science:

• Materials Science
• Chemical Engineering
• Environmental Science

Background:

• Diamond wire saw silicon slurry (DWSSS) is a waste byproduct of solar-grade silicon wafer production.
• DWSSS contains valuable 6N grade high-purity silicon, suitable for recycling.
• Existing silicon extraction methods from DWSSS suffer from low recovery rates and environmental pollution.

Purpose of the Study:

• To develop an efficient and environmentally friendly method for extracting high-purity silicon from DWSSS.
• To investigate the feasibility of using flotation for silicon recovery from DWSSS.
• To elucidate the adsorption mechanism of dodecylamine (DDA) on silicon surfaces.

Main Methods:

• Flotation experiments were conducted using DWSSS.
• Optimization of flotation parameters including dodecylamine (DDA) dosage and pH.
• Analysis of flotation kinetics and adherence to the first-order rate model.
• Density Functional Theory (DFT) calculations to study the adsorption mechanism.

Main Results:

• Maximal silicon recovery reached 98.2% under optimized conditions (0.6 g·L⁻¹ DDA, natural pH, 24 min).
• Flotation process kinetics followed a first-order rate model.
• Dodecylamine (DDA) was found to adsorb onto silicon surfaces, enhancing floatability.
• DFT calculations confirmed the spontaneous adsorption of DDA onto silicon.

Conclusions:

• Flotation is a highly efficient method for extracting silicon from DWSSS.
• The study provides a viable and sustainable option for high-purity silicon recycling.
• Understanding the DDA-silicon interaction mechanism is key to optimizing the flotation process.