Deep iron removal technology for low-iron quartz sand: an innovative solution for photovoltaic and ultra-white glass manufacturing

Abstract: This paper discusses the core difficulties, process routes and innovative solutions of low iron quartz sand deep iron removal technology.ElevateSilica, as a professional silica sand technology and equipment provider, helps customers in high-end applications such as photovoltaic glass and ultra-white glass to obtain stable and high-quality low-iron quartz sand with SiO₂ ≥ 99.5% and Fe₂O₃ ≤ 0.008%, by virtue of its high-efficiency deep iron removal technology and line integration capability, Fe₂O₃≤0.008% of high quality low-iron quartz sand, significantly enhancing product value and market competitiveness.

Keywords: low iron quartz sand depth iron removal technology, low iron quartz sand, photovoltaic glass quartz sand, ultra-white glass raw materials, quartz sand iron removal method, Fe2O3 control, silica sand purification, ElevateSilica

Why low iron quartz sand becomes the "core cornerstone" of high-end glass?

In the photovoltaic industry and the rapid development of high-end building materials, photovoltaic glass and ultra-white glass has become a key material because of its high transmittance, excellent strength and stable chemical properties. The realization of these excellent properties is extremely dependent on the purity of its core raw material, low-iron quartz sand.

Iron (mainly in the form of Fe₂O₃) is the main impurity that affects the transmittance and color of glass. Even a trace amount of iron can significantly reduce the whiteness and transmittance of glass, directly affecting the power generation efficiency of PV modules and the aesthetics of high-grade buildings. Therefore, the level of low-iron quartz sand depth iron removal technology directly determines the quality and market tier of the final glass product.

Typical index requirements of low-iron quartz sand for high-end applications:

• Solar photovoltaic glass, ultra-white glass raw materials: SiO₂ ≥ 99.5%, Fe₂O₃ ≤ 0.008%

• Optical glass raw materials: SiO₂ ≥ 99.7%, Fe₂O₃ ≤ 0.0015%.

Second, the technical challenges and core difficulties of low iron quartz sand depth iron removal

To reduce the iron content in ordinary quartz sand to eight parts per million (0.008%) or even lower, is a very challenging work, the main difficulties are:

1. Complex state of existence: Iron element not only exists in free state and adsorption state, but also may be embedded in quartz crystals in the form of micro inclusions and quasi-isomers, which is difficult to be effectively removed by conventional physical methods.

2. Removal efficiency bottleneck: When the iron content drops to a lower level, the efficiency of the traditional single magnetic separation or acid washing method decreases, making it difficult to realize cost-effective deep purification.

3. Risk of secondary pollution: In the crushing, grinding, classification and other processing processes, the wear and tear of equipment may introduce new iron impurities, resulting in the dilemma of "the more you process, the higher the iron".

4. Stability and consistency: How to produce high quality low-iron quartz sand with consistent composition under the conditions of different batches of raw ore is a serious test of the reliability of the process control system and equipment.

ElevateSilica's Innovative Deep Iron Removal Technology System

Aiming at the above industry pain points, ElevateSilica integrates multiple process routes to form a unique advantage of low iron quartz sand depth iron removal technology solutions.

1. Multi-process synergistic deep iron removal process:

The core of our technology lies in the synergistic process of " physical pre-treatment as a pioneer, deep chemical purification as a guarantee ".

• Stage 1: High-efficiency physical iron removal (pre-enrichment)

  • Fine crushing and grinding: High-purity ceramic liners, zirconium balls and other wear-resistant media are used to minimize secondary iron pollution in the process.

  • Strong Magnetic Separation and Gradient Magnetic Separation: Equipped with self-developed high gradient strong magnetic separator, which can effectively remove most of the free and adsorbed iron including weakly magnetic minerals.

• Stage 2: Deep chemical iron removal (core purification)

  • Mild and efficient acid washing technology: This is the core of our technology. Through the specially formulated mixed acid formula and controlled reaction at specific temperature and concentration, it can effectively leach out the iron in the inclusions, while minimizing the corrosion of the quartz skeleton and improving the yield.

  • Compound leaching and complexation technology: For particularly stubborn iron impurities, compound agents are used to stabilize and dissolve them out through complexation reaction, realizing the limit reduction of Fe₂O3 content.

• Stage III: Purification and dewatering drying

  • High-purity water washing and wastewater recycling: Multi-stage counter-current washing with high-purity water thoroughly removes residual acid and dissolved iron ions. At the same time, our system realizes the recycling and neutralization of waste acid to meet the requirements of environmental protection.

  • Specialized drying system: drying in a clean environment to avoid secondary pollution.

2. Advantage of core technology and equipment:

• Specialized deep iron removal device: realizes efficient and uniform mixing and reaction between chemicals and slurry, and improves iron removal efficiency.

• The whole line of anti-pollution design: from the entrance of raw materials to the exit of finished products, the whole line adopts anti-rust and anti-wear design, which fundamentally eliminates the secondary pollution.

Why choose ElevateSilica's low iron quartz sand deep iron removal solution?

1. Excellent and stable index: Our mature technology line can stably produce Fe₂O₃ ≤ 0.008% sand for photovoltaic glass, and even reduce Fe₂O₃ to below 0.005% according to the demand to satisfy the higher-end applications such as optical glass.

2. Comprehensive Cost Advantage: Through the synergistic optimization of multiple processes, the consumption of strong acid and energy is reduced; the efficient recycling system reduces the cost of wastewater treatment, which brings better economic benefits to customers.

3. Rich project experience: We have successfully constructed low-iron quartz sand purification production lines for many domestic and foreign silica sand enterprises, and are familiar with the characteristics of quartz stones from various regions and sources, so we are able to provide the most suitable customized solutions.

4. Full-cycle technical services: From raw ore evaluation, laboratory trial, process package design, core equipment supply to line integration and production commissioning, we provide one-stop services to ensure that the project reaches the production standard smoothly.

With the increasingly fierce competition in the high-end glass industry, having stable and efficient iron removal technology for low iron quartz sand is the key to the core competitiveness of enterprises, and ElevateSilica is willing to be your most trustworthy partner with innovative technology, reliable equipment and full range of services to light up the future of the photovoltaic industry and create a transparent and pure glass world together.

Consult our technical experts to get your exclusive low iron quartz sand deep iron removal solution!