High-purity quartz sand beneficiation and purification method

Recently, the Ministry of Natural Resources announced that high-purity quartz sand has officially become the 174th new mineral in my country. It is required that the purity of silicon dioxide after beneficiation and purification of high-purity quartz ore shall not be less than 99.995% (4N5 grade), and the content of impurities and inclusions can meet the stringent requirements of high-tech fields such as semiconductors and photovoltaics. The announcement of this news has injected new vitality into the development of related industries. This article will take this opportunity to introduce the standards of high-purity quartz sand and the beneficiation and high-purity quartz sand purification technology.

01Standards and applications of high-purity quartz sand

Usually, when the purity of high-purity quartz sand reaches 4N (99.99%) grade, it has reached the material basis of high-end products. However, in more advanced fields such as semiconductors, the purity of silicon dioxide needs to reach 4N5 (99.995%) grade or even 5N (99.999%) grade and above. The following is a high-purity quartz sand grade classification table:

02High-purity quartz sand beneficiation method

The conventional high-purity quartz sand beneficiation method is mainly physical beneficiation and chemical beneficiation.

1. Gaochun quartz sand physical beneficiation method

quartz Magnetic separation: It mainly uses the magnetic difference between quartz and other magnetic impurities to achieve enrichment through high-gradient magnetic separation. This type of magnetic separation equipment generates a strong magnetic field of 4-5T and forms a high-gradient field strength with stainless steel wool media to remove magnetic impurities such as hematite and magnetite. The iron removal efficiency can reach 98%.

quartz Flotation: It is mainly based on the difference in surface electrical properties between quartz sand and silicate minerals (feldspar, mica, etc.), and the anion and cation flotation method is used to complete the beneficiation. First, the cationic positive flotation uses sodium oleate to adsorb quartz with a collector in an alkaline environment (pH=9-10), and then uses cationic reverse flotation to capture impurities in an acidic environment. Optimizing the reagent ratio and pH value can reduce the content of impurities such as Al₂O₃.

quartz Gravity separation: mainly based on the density difference between quartz sand and other impurity minerals, spiral chute, shaking table, hydrocyclone and other gravity separation equipment are used to achieve separation. The spiral chute uses the combined effect of gravity, centrifugal force and water flow to allow the high-density quartz sand particles to settle quickly; the shaking table uses the reciprocating motion of the bed surface, and under the action of water flow flushing and bed vibration, the high-density quartz sand is first deposited on the bottom of the bed surface; the cyclone, under the action of centrifugal force, allows the high-density quartz sand particles to move downward along the wall of the device and be discharged from the bottom flow, thereby achieving effective separation of minerals.

2. High-purity quartz sand chemical beneficiation method

Acid leaching process: Using HCl-H₂SO₄-HF ternary mixed acid system, react at 80-90℃ for 6-8 hours to dissolve metal oxide impurities. The introduction of ultrasonic enhanced mass transfer can greatly reduce the content of impurities such as K₂O and Na₂O, and improve the acid leaching efficiency and impurity dissolution rate.

Chlorination roasting: It is to feed Cl₂ or HCl gas at a high temperature of 1200-1400℃, react chemically with impurities such as iron and titanium, and generate volatile metal chlorides for discharge. After roasting, the quartz sand product is quickly cooled to prevent impurities from being adsorbed again or reacting with the quartz sand during the cooling process. After the cooled quartz sand is screened, ground and processed, a high-purity quartz sand product can be obtained.

The above is an introduction to the content of high-purity quartz sand. For a long time, my country has been relying on imports in the field of high-purity quartz sand. Now, with the continuous innovation of my country's technology, it provides strong technical support for the domestic substitution of high-purity quartz sand.

In the future, we will accelerate the development of prospecting and exploration, so that domestic high-purity quartz sand can promote the cost reduction and efficiency increase of the photovoltaic industry and enhance the competitiveness of my country's photovoltaic industry in the world.

Xinhai Mining has rich experience in quartz sand mining and beneficiation. It can provide customers with an integrated innovative model covering mining technical consultation and experimental research and mining design, complete equipment manufacturing and procurement, civil engineering construction and installation, commissioning and delivery, mining construction management, mining production and operation management and services, which can greatly improve mining efficiency and create more additional value for customers! If you have any needs, please feel free to consult.