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High-Purity Quartz Sand Extraction Process: Technological Evolution, Eco-Friendly Acid Leaching, and Semiconductor-Grade Production (2025 Updated Guide)

1. Core Process: From Basic Purification to Advanced Refinement

High-purity quartz sand (SiO₂ ≥99.995%) requires physical-chemical hybrid processes for multi-dimensional impurity removal. Current mainstream techniques include three stages:

1. Physical Pretreatment

• Abrasion & Grading: Hydraulic scrubbing removes surface impurities, while vibrating screens separate particles by size.

• Magnetic and Flotation Separation: 15,000 Gauss magnetic separation removes iron, and reverse flotation eliminates feldspar/mica (removal rate >70% with H₂SO₄ and petroleum sulfonate) .

• Microwave Fracturing: Microwave-induced thermal expansion (based on dielectric differences) increases impurity exposure by 50% .

2. Chemical Deep Purification

• Chlorination Roasting: HCl gas at 1000–1500°C volatilizes lattice-bound Al³⁺, K⁺, and Na⁺. Unimin Corp. pioneered this for 5N-grade purity .

• Supercritical Acid Leaching: CO₂ supercritical fluid with trace H⁺ dissolves Al/Ca impurities (50% efficiency boost, 40% acid reduction) .

3. Terminal Refinement

• Nanofiltration: Ceramic membranes (10–50 nm pores) block submicron contaminants .

• Laser Stripping: High-energy lasers vaporize surface residues (precision: 0.1 ppm) .

2. 2025’s Top 4 Technological Breakthroughs

1. Microwave Chlorination Roasting System
   Combines microwave heating (800–1100°C) and NH₄Cl, reducing Al content from 738.8 ppm to 17.9 ppm with 40% lower energy consumption .

2. Bio-Chemical Synergistic Purification
   Uses Aspergillus niger metabolites (oxalic + citric acids) and low-concentration HF leaching, achieving 97.3% Fe removal and 60% acid reduction .

3. AI-Driven Quality Control

• AI-based SEM/EDS analysis accelerates raw material screening by 70% .

• Real-time XRF monitoring adjusts acid concentration and reaction duration .

4. Fluorine-Free Green Refining
   H₃PO₄ dissolves Al₂O₃ at 260°C (87% efficiency), while NaOH-HCl sequential treatment reduces Al from 62.8 μg/g to 17.01 μg/g .

3. Eco-Friendly and Cost Optimization Trends

1. Circular Economy Integration
   Membrane electrolysis recovers 90% HF, while waste heat reuse cuts energy consumption by 30% .

2. Raw Material Adaptability
   African pegmatite quartz achieves <8 ppm Al impurities, supported by dynamic process packages for customized purification .

4. Industry Applications & Market Landscape

• Photovoltaic Sector: Domestic 4N8-grade quartz replaces imported crucible liners .

• Semiconductor Sector: 6N-grade quartz for EUV lithography lenses remains import-dependent (32% localization rate) .