Beneficiation Method and Process Flow of High Purity ...

Silicon dioxide (SiO2) is the main chemical component of quartz sand and high purity quartz sand is defined as having a silicon dioxide content of 99.9% or more. As one of the most important industrial raw materials, quartz can be used in industries such as glass, building materials and plastics. The electronics, aerospace, fibre optic communication and military industries have requirements for the purity of silica sand. This article explains the beneficiation method and process flow of high purity quartz sand.

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1.High purity quartz sand beneficiation methods

In industrial production, the purification methods of high purity quartz sand mainly contain physical purification, chemical purification and biological purification.

1.1 Physical purification of high purity quartz sand

Common physical refining methods for high purity quartz include water washing - graded desliming, scrubbing, gravity separation, magnetic separation and flotation, one or a combination of these forms can be used to remove impure minerals from silica sand and achieve refining requirements.

Water washing - Classified desliming/scrubbing

In quartz sand beneficiation, particles below 0.1mm are generally referred to as mineral sludge because the finer the particle size, the lower the silica content and the greater the relative impurity mineral content. The impurity minerals are removed by water washing or scrubbing to improve the concentrate grade.

Gravity separation

Gravity separation mainly uses the difference in density, size and shape of the mineral particles to produce different directions of movement and distribution speeds under the action of water and centrifugal force, thus achieving separation.

Magnetic separation

Magnetic separation is the removal of magnetic minerals such as haematite, brown iron and black mica from minerals by means of magnetic separation equipment, using the magnetic differences between quartz and impurity minerals.

Flotation

Flotation is the use of chemicals and equipment to change the nature of the mineral surface to remove a range of impurities present in the mineral under acidic conditions, separating out high purity quartz sand.

1.2 Chemical purification of high purity quartz sand

Among the chemical purification methods for high purity quartz sand, acid leaching and alkali leaching methods are more effective for the purification of high purity quartz sand.

Acid leaching

The acids commonly used for acid leaching are mainly sulphuric acid, hydrochloric acid, nitric acid, etc. When the acid concentration is low, it is better to remove impurities such as iron, aluminium and magnesium; when the acid is thicker, it is better to remove impurities such as titanium and chromium.

Alkaline leaching

Alkaline leaching is the use of alkaline solutions, usually sodium hydroxide or sodium carbonate solutions to dissolve aluminosilicate impurities, for the purification of quartz sand.

1.3 Biopurification of high purity quartz sand

The biological purification method of high purity quartz sand is mainly through microbial leaching purification, which is achieved through the physiological properties of microorganisms and their metabolites, after oxidation, dissolution and decomposition.

2. High purity quartz sand process flow

In the beneficiation process, the process flow of high purity quartz sand mainly contains the following links:

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2.1 Quartz sand crushing

Generally two-stage crushing process is adopted, firstly coarse crushing by jaw crusher, after crushing, the crushed material is conveyed by belt conveyor to vibrating screen for screening, the unqualified material is sent to cone crusher for fine crushing, the qualified material is conveyed to powder bin.

2.2 Grinding and classification

The main purpose of the grinding process is to grind the raw ore to a certain size and to dissociate the quartz sand from the vein minerals. The classifying equipment cooperates with the grinding equipment to produce quartz sand materials with qualified particle size.

2.3 Magnetic separation

The magnetic separation process uses a wet magnetic separator for primary separation, which is used to remove hematite, limonite, ilmenite and their congeners particles present in the quartz sand.

2.4 Flotation

Flotation removes mica and iron oxide from quartz. The flotation operation is carried out using sulphuric acid as an adjusting agent, sodium petroleum sulphonate as a trapping agent and pine alcohol oil as a foaming agent.

2.5 Acid leaching

After two separations by magnetic separation and flotation, impurities are still present in the quartz in the form of flecks or inclusions. To remove this impurity, acid leaching is required, using a mixture of different acids to remove the different impurities.

2.6 Washing

Soluble impurity residues adhere to the surface of the quartz sand after acid leaching and need to be removed by washing. The washing of the acid-impregnated minerals causes the impurities and residues on the quartz surface to diffuse into the solution, thus completing the cleaning process.

The above mainly describes the beneficiation method and process flow of high purity quartz sand. When building a beneficiation plant, in order to obtain high purity quartz sand, the appropriate beneficiation process should be selected according to the nature of the ore, therefore, it is recommended to tailor the appropriate process solution to obtain high purity quartz sand through beneficiation test analysis.

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1. Washing-classifying-desilting: In the quartz sand beneficiation process, the fine-grained grade with a particle size of less than 0.1 mm is usually called slime. For quartz sand with a large amount of clay and ore mud, as the particle size becomes finer, the grade of silica gradually decreases, while impurities such as iron and aluminum rise instead. Using water washing-classifying-desilting method can effectively improve quartz grade.

2. Scrubbing: The effect of water-washing-grading desilting is poor for the thin film iron and adhesion impurities on the surface of quartz sand. This requires the removal of the thin film iron and adhesion impurities suitable for the sand surface by means of mechanical force and the abrasive force between the sand particles. After the grading desilting, a better impurity removal effect can be achieved.

3. Gravity separation: It screens minerals according to their different gravity. Due to the difference in density, the mineral particles are affected by the fluid force and mechanical force in the medium, resulting in loose stratification, so that the ore particles are separated.

4. Magnetic separation: It separates the quartz sand&#;s magnetic impurity minerals and particles. A strong magnetic separator to separate the impurity iron in quartz is the key link. Magnetic separation can remove mechanical iron minerals (hematite, limonite, pyrite, ilmenite, biotite, etc.) mixed in quartz sand. It can also remove weak magnetic minerals and inclusions and disseminate impurities containing iron minerals.

5. Flotation: Flotation machine is the process of separating mineral particles by different physical and chemical properties on the surface of the mineral particles. The main function is to remove the related mineral mica and feldspar from the quartz sand.

6. Dewatering: The material is dehydrated and dried to obtain the required products, and the actual configuration should be adjusted according to the production needs.

The physical beneficiation method can only remove the impurities of mineral structure and rarely remove the impurities on the surface of quartz sand. The purer the quartz sand, the higher the use value, so it is necessary to further purify the quartz sand after flotation. Contact us to get process details and equipment factory price!

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