How to purify quartz sand to remove impurities? Quartz sand purification method!

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Quartz sand is the main raw material for ceramics, glass, optical fiber, semiconductor and other industries. The mineral impurities in the quartz sand need to be purified and separated, and then used as industrial raw materials. Among them, high-tech fields such as semiconductors, optical fibers, and aerospace have very high purity requirements for quartz sand, so it is critical to effectively improve the purity of quartz sand. So how to purify quartz sand and remove impurities? What are its purification processes? Let’s find out together!Commonquartz sand purification processesflow It is divided into four stages: pre-selection preparation operation, pre-selection operation, mineral sorting operation and deep purification operation.

1.Preparation work before quartz sand purification and selection

The preparation operations before quartz sand selection mainly include calcination, water quenching, grinding, classification and other processes. The main purpose of this operation is to achieve sufficient monomer dissociation of quartz sand and control the particle size range of the product to facilitate subsequent selection operations.

Calcination and water quenching:Before grinding, the quartz needs to be calcined at about 1000°C and quenched with water. Under high-temperature calcination, the quartz will undergo crystal transformation with the gangue minerals; then water quenching is performed. Since the expansion rates of gangue impurities and quartz are different , under the action of water quenching, the temperature drops sharply and a large number of cracks are generated inside the particles, which facilitates the grinding operation.

Grinding and grading:The cracked quartz sand minerals enter the grinding system. After grinding, the inclusion impurities are easily exposed on the surface of the quartz ore particles, and then they are graded and then ground again, which can strengthen the monomer dissociation effect of quartz and gangue minerals.

2.Quartz sand purification and pre-selection operation

The pre-selection operations of quartz sand mainly include water washing, desliming and scrubbing. During the grinding process of quartz raw ore, some easily muddied minerals will form fine-grained slime, which will affect subsequent sorting operations. Therefore, it is necessary to carry out pre-selection to remove muddy clay minerals and thin film iron, bonding and muddy impurity minerals on the surface of quartz sand.

Washing and desliming:Use equipment such as spiral washers, trommel screens, hydrocyclones, desliming hoppers, and hydraulic classifiers to wash and deslim the quartz raw ore. The main purpose is to remove clay minerals from quartz sand.

scrub:by giving Appropriate chemicals are added to the scrubbing machine to increase the electrical repulsion between the impurity minerals and the surface of the quartz particles. With the help of mechanical force and the peeling force between the sand particles, the film iron, bonding and muddy impurity minerals on the quartz surface are removed and further crushed. An aggregate of minerals that has not yet become a single entity.

3.Quartz sand purification and sorting operation

Yingsha mineral separation operation is based on the differences in physical and chemical properties between quartz and associated gangue minerals. There are several methods such as magnetic separation, flotation, gravity separation and electric separation.

Gravity quartz sand purification:Utilizing the difference in density between quartz sand and gangue minerals, they are affected by different fluid forces and mechanical forces in the medium, resulting in loose stratification, so that the ore particles are separated. Available equipment is: jigs, shakers, spiral chutes and centrifugal concentrators.

Magnetic separation quartz sand purification:Quartz sand does not have magnetic separation, but the minerals contain other magnetic impurities, such as hematite, limonite, pyrite, ilmenite, biotite, etc., which can be separated by magnetic separation (multi-stage weak magnetic-strong magnetic method) It can remove the iron-containing minerals, and at the same time, it can also remove inclusions and conjoined bodies with magnetic minerals. Available devices are:Wet type strong magnetic separatorand High gradient magnetic separator.

Flotation quartz sand purification:Generally, when methods such as scrubbing, gravity separation, and magnetic separation cannot achieve the desired desliming effect, flotation must be used to remove feldspar, mica, and various non-magnetic associated impurities present in the mineral. Flotation is divided into two types: fluorine flotation and fluorine-free flotation. Among them, fluorine flotation uses cationic collectors and hydrofluoric acid activators to achieve flotation within the acidic pH range; fluorine-free flotation uses the differences in structure and composition of quartz and feldspar to appropriately adjust the cationic mixed capture. According to the ratio of collector, limited flotation of feldspar is carried out to achieve separation. Commonly used flotation equipment includeMechanical stirring flotation machine(such as SF type, JJF type, BF type) and inflatable agitation flotation machine (KYF type, XCF type), etc.

4.Quartz sand deep purification operation

The main reason for deep purification of quartz sand is that inclusions and impurities in the crystal lattice cannot be effectively removed through conventional selection methods alone, resulting in low purity of quartz sand. Therefore, high-temperature (atmosphere) roasting and acid leaching are used for deep purification.

High temperature (atmosphere) roasting:By adding chlorine and HCl and roasting at high temperature at 800~1600°C, the inclusions expand and rupture rapidly when heated, exposing the impurities in them to the quartz surface. During this process, the impurities migrate to the quartz surface along with the quartz crystal structure transformation process; Or under the action of high temperature atmosphere (such as HCl), it reacts with the impurities in the crystal lattice, causing the impurities to be transferred to the quartz surface, and then the impurities are removed by acid leaching.

Acid leaching:Add quartz sand to the mixed acid solution, and leach with intermittent stirring at room temperature. The general time is 24 hours; if under heating conditions, use stirring and leaching,The time is generally 2 to 6 hours,Just wash and dry. Commonly used acids for acid leaching include sulfuric acid, hydrochloric acid, nitric acid and hydrofluoric acid; reducing agents include sulfurous acid and its salts.

The above are the main methods and processes for quartz sand impurity removal and purification. In the actual mineral processing process, the choice of quartz sand impurity removal and purification method needs to be based on the type and content of impurities. Therefore, mineral processing tests need to be carried out. Through test analysis, design Suitable quartz sand purification process plan and complete set of quartz sand purification equipment。