Quartz Sand Beneficiation and Purification Technologies

Quartz sand (silica sand) is a widely utilized non-metallic mineral raw material found in various industries, including construction, glass manufacturing, ceramics production, and casting. Although these sectors have a high demand for quartz sand, their requirements for raw material quality tend to be low. High-quality quartz sand generally necessitates minimal to no purification to meet industry standards. In contrast, advanced fields such as aerospace, atomic energy technology, laser communication, optical cable communication, and the military have stricter specifications for quartz sand. This sand must undergo extensive mineral processing and purification processes to attain high-purity or ultra-high-purity levels. As technological advancements continue to grow, the demand for silicon in these high-tech sectors is on the rise. Thus, enhancing quartz sand purification technology is of considerable practical significance, enabling low-cost, large-scale production of high-purity and ultra-high-purity quartz sand. This article will introduce common quartz sand beneficiation technologies, including scrubbing, desludging, magnetic separation, and flotation.

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• 01

  Quartz sand washing + graded desliming process

• 02

  Quartz sand scrubbing process

• 03

  Quartz sand magnetic separation process

• 04

  Quartz sand flotation process

01

Quartz sand washing + graded desliming process

The SiO₂ grade in quartz sand typically decreases as the grain size diminishes, while the concentrations of impurity minerals like iron and aluminum increase. This trend is especially pronounced in quartz sand containing substantial amounts of clay minerals. Therefore, washing, classification, and desliming treatments are essential before the selection of quartz sand raw ore. These treatment processes can effectively eliminate clay minerals and other impurities, significantly enhancing the purity of quartz sand and guaranteeing the quality of subsequent processing and applications.

Commonly used water washing equipment encompasses ore washers, spiral ore washers, and drum ore washers, which efficiently remove soil and impurities from quartz sand. Classification instruments such as spiral classifiers and vibrating screens help separate ores of varying particle sizes, further enhancing the quality of quartz sand. Desliming equipment, including high-frequency screens and cyclones, effectively eliminate clay minerals and fine argillaceous iron, improving quartz sand purity.

02

Quartz sand scrubbing process

The scrubbing process can be categorized into two methodologies: rod mill scrubbing and mechanical scrubbing. The efficacy of mechanical scrubbing is significantly influenced by the design characteristics and configuration of the scrubbing machine. Additionally, process factors, such as scrubbing time and concentration, play crucial roles. Extreme scrubbing concentrations, whether too high or too low, can hinder the removal of impurity minerals and complicate the quartz sand purification process. Scrubbing time should align with the initial quality standards; excessive durations not only elevate equipment wear and energy consumption but also increase mineral processing and purification costs. Therefore, controlling scrubbing time reasonably is vital to ensure product quality and optimize production efficiency while minimizing operating expenses.

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Common scrubbing equipment includes rod mills, drum washers, and spiral washers. Mechanical scrubbing devices, such as drum washers and spiral washers, are commonly employed to remove surface impurities. Nonetheless, the effectiveness may vary for certain quartz sand ores. Consequently, the rod mill scrubbing process is an alternative that can enhance quartz sand purity, particularly for ores that exhibit poor mechanical scrubbing results.

03

Quartz sand magnetic separation process

The magnetic separation process is effective in eliminating weakly magnetic impurity minerals like hematite, limonite, and biotite from quartz sand ores, thereby elevating quartz sand purity. Strong magnetic separation typically employs wet strong magnetic separators or high-gradient magnetic separators. These machines generate a strong magnetic field in a wet environment, facilitating efficient separation of fine and micro particles, further enhancing quartz sand quality. Wet strong magnetic separators target weakly magnetic impurity minerals, while weak magnetic or medium magnetic separators can extract strong magnetic minerals like magnetite.

04

Quartz sand flotation process

The flotation method effectively removes non-magnetic impurity minerals, such as feldspar and mica, from quartz sand. In the separation of quartz from feldspar, cationic collectors and hydrofluoric acid activators are commonly utilized in acidic pH ranges. However, because of the environmental risks posed by fluorinated wastewater, fluorine-free acid flotation alternatives can achieve successful feldspar and quartz separation. This approach employs sulfuric acid or hydrochloric acid to adjust the pH to approximately 2, coupled with a mixed collector system of higher aliphatic amine salts and sodium petroleum sulfonate.

The isoelectric points of mica and quartz are similar, complicating their separation. To resolve this challenge, anionic collectors can be employed in acidic environments, or a mixture of anionic and cationic collectors can be used in alkaline conditions. This technique effectively separates mica and quartz, leading to favorable sorting outcomes.

In the beneficiation process of quartz sand, the integration of diverse processing technologies can substantially enhance its purity, satisfying various application requirements. As technology progresses, optimizing these mineral processing methods and combining them with innovative processing techniques will offer more efficient and cost-effective solutions for quartz sand purification, catering to the growing demands of high-tech applications.

This document discusses the processing of sand and silica sand into various materials. It begins by outlining examples of mineral processing techniques for sand, silica sand, and heavy mineral sand. For processing sand and silica sand, techniques include extracting, washing, classifying, and removing impurities from the sand through methods such as screening, attrition scrubbing, hydrocyclones, and magnetic separation. The processed sand can be further transformed into silicon, silicon carbide, and silicone by reducing silica to ferrosilicon, purifying it through trichlorosilane distillation, and utilizing the Siemens process to deposit high-purity silicon. Additionally, heavy mineral sands can be separated into minerals like zircon and rutile.

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