From ordinary quartz sand to high-purity quartz sand purification program: technology path, core process and overall solution

Abstract: How to purify ordinary quartz sand (SiO₂ content is usually below 99.5%) into high-purity quartz sand (SiO₂≥99.99%-99.999%) that meets the requirements of high-technology fields, such as photovoltaic, optical fiber, semiconductor, etc., is one of the core challenges of the modern materials industry. This paper systematically describes the complete purification solution from common quartz sand to high purity quartz sand, including the four major stages of raw material evaluation, physical pretreatment, in-depth chemical purification and final processing, and focuses on the analysis of the core technology.ElevateSilica, with its comprehensive process technology and equipment integration capabilities, provides customers with customized high purity quartz sand purification solutions, ranging from laboratory validation to industrialized production. purification solutions.

I. Introduction: Crossing the Purity Chasm

There is a huge "purity gap" between ordinary quartz sand and high purity quartz sand. This gap is not only the percentage difference of silica content, but also the limit of its internal impurity types, content and existence of the form of control. High-purity quartz sand (usually referred to as SiO₂>99.99% of the product) is the manufacture of photovoltaic crucibles, fiber optic pre-fabricated rods, high-end optical devices and electronic components of the key basic materials. To realize the transformation from ordinary quartz sand to high-purity quartz sand requires a set of scientific, precise and economically feasible purification program.

Second, the cornerstone of the purification program: raw material feasibility assessment

Not all common quartz sand is suitable for purification to high purity grade. The first step in the program is to accurately assess the raw materials.

• Mineralogical analysis: Determine the type and content of vein minerals (e.g. feldspar, mica, clay).

• Impurity endowment analysis: The key analysis is whether impurities such as iron, aluminum, potassium, sodium, etc., are in separate mineral phases or are present within the quartz as fluid inclusions, lattice substitutions, etc. The latter is the main challenge in purification. The latter is the main difficulty of purification.

• Process Mineralogy Evaluation: To judge the potential and economy of this raw material to reach the target grade through the existing technology path through small trial experiments.

Three, from ordinary quartz sand to high-purity quartz sand four-stage purification program

A complete purification program is a multi-step, multi-technology synergistic systematic project, and ElevateSilica's program is divided into the following four stages:

Stage 1: Pretreatment and Physical Purification (Pre-Enrichment)
Objective: To remove most of the individual mineral impurities and prepare the raw material for deep chemical purification.

1. Crushing and Grinding: Using high purity equipment such as multi-layer roller crushers and cone crushers, the ore is gradually crushed to the size of monomer dissociation to minimize secondary pollution.

2. Scrubbing and desliming: Use mechanical force to scrub the thin film iron and adhesive impurities on the surface of quartz, and remove the fine-grained clay minerals through hydraulic desliming.

3. Gravity separation and magnetic separation:

   • Gravity sorting: Removal of dense minerals such as garnet and tourmaline.

   • Magnetic separation: the core physical means of iron removal. In order to remove strong magnetic minerals (such as magnetite) using medium-strength magnetic separation, and then use high gradient strong magnetic separator to remove hematite, black mica and other weakly magnetic minerals, can significantly reduce the Fe₂O₃.

Stage 2: Deep Chemical Purification (Core Process)
Objective: To remove the trace impurities wrapped on the surface or inside the quartz particles, which are difficult to be removed by physical methods.

1. Acid leaching (pickling) purification: the mainstay of this stage.

   • Principle: Using a mixture of acids (e.g. hydrochloric acid, sulfuric acid, oxalic acid, hydrofluoric acid, etc.) to react with the impurity minerals under heating conditions to dissolve them.

   • ElevateSilica advantages:

     • Customized Acid Formulation: Optimize the type, concentration and ratio of acids according to the characteristics of the impurities in the raw material to achieve the best balance between efficient leaching and reduced quartz loss.

     • Enhanced reaction conditions: Stirred leaching and ultrasonic assisted leaching are used to enhance acid permeability and improve the removal efficiency of inclusions.

     • Environmental protection and recycling: Equipped with acid mist recycling and waste acid regeneration system to realize environmentally friendly production.

Phase III: Thermal chlorination purification (for very high purity requirements)
Objective: For very high purity quartz sand (e.g. fiber optic, semiconductor grade) requiring SiO₂>99.995%, trace alkali metal and bubble inclusions in the crystal lattice need to be removed.

• Principle: Chlorine or chloride gases (e.g. Cl₂, HCl) are introduced at high temperatures (above 1000°C) and in an inert atmosphere. These gases react with metal impurities (e.g. Na, K, Li) in the quartz lattice to form gaseous chlorides, which are then carried away.

• APPLICATIONS: This technology has an extremely high threshold and is key to the preparation of top quality high purity quartz sand, which is typically used in the back-end treatment of the final product.

Stage 4: Final Processing and Quality Control

1. High Purity Washing and Dewatering: Multi-stage countercurrent washing with ultrapure water until the effluent is neutral, ensuring that no acids or soluble ions remain.

2. Drying and Packaging: Drying in a clean environment and packaging to prevent contamination.

3. Comprehensive quality testing: ICP-OES/MS is used to analyze the chemical composition, laser particle size meter to analyze the particle size distribution, and electron microscope to analyze the morphology, to ensure that the product fully meets the standards.

Core Benefits of ElevateSilica's Purification Solutions

1. Customized process design: We understand that "one mine, one case", never provide a one-size-fits-all solution. Based on your raw material characteristics and target product standards, we can customize the most economical and efficient purification solution.

2. Technology Integration and Optimization: We not only master individual technologies, but are also good at combining and linking physical, chemical, thermal and other process routes to maximize the efficiency of the entire line.

3. Self-developed core equipment: We provide self-developed core equipment from energy-efficient grinding and classifying systems, deep iron removal and magnetic separators to automatically controlled environmental pickling lines to ensure that the technology is implemented and the performance is guaranteed.

4. Complete line delivery and continuous support: We provide turnkey projects from laboratory tests, pilot scale-up to complete line design, equipment manufacturing, installation and commissioning, and technical training, and provide customers with continuous support for production optimization.

The path of purification from ordinary quartz sand to high purity quartz sand is a path full of technical challenges. ElevateSilica, as a professional silica sand technology and equipment solution provider, is willing to be your most solid partner with our systematic high-purity quartz sand purification solutions and reliable engineering implementation capabilities to break through the purity limit and empower the future development of China's high-end manufacturing industry. manufacturing industry in China.

Contact us today for a customized purification solution and feasibility analysis report based on your quartz sand raw material!