The production of high-purity quartz sand is a technically demanding and
meticulous process, typically used in the manufacturing of applications such as
photovoltaics, semiconductors, optical fibers, precision instruments, etc. that
require extremely high purity. In order to ensure that quartz sand meets high
purity standards, multiple links need to be strictly controlled during the
production process, including raw material selection, processing technology,
equipment configuration, and quality testing. The following are the main
production requirements for high-purity quartz sand:
1. Selection of raw materials
The quality of high-purity quartz sand directly depends on the purity and
quality of the raw materials. Raw materials are usually made from parts of ore
with high silicon content, requiring:
High purity of ore: When selecting quartz ore, the silicon content should be
above 90%, preferably above 98%. The impurities such as iron, aluminum, calcium,
and sodium in the raw materials should be kept as low as possible to ensure high
purity of the produced quartz sand.
Impurity control: There should not be a large amount of iron minerals, heavy
metals, or other non silicon components in the raw materials. Pre selection and
impurity removal of ore are necessary to avoid the impact of impurities on the
final product.
2. Processing technology requirements
The production process of high-purity quartz sand is complex and targeted,
mainly involving the following key steps:
(1) Raw material pretreatment
Crushing and screening: Firstly, quartz ore is subjected to coarse crushing,
fine crushing, and screening to obtain ore of appropriate particle size. When
crushing, it is important to avoid excessive grinding to prevent the production
of large amounts of fine powder that may affect the final quality.
Cleaning: Wet or dry cleaning techniques are used to remove soil, iron
minerals, and other impurities from the surface of the ore. Quartz sand
scrubbing machines or water washing equipment are often used to achieve this
process.
(2) High temperature smelting
High temperature melting: In order to improve the purity of quartz sand,
quartz ore is usually processed through high-temperature smelting or reduction
processes. Use an electric furnace or high-temperature furnace to melt quartz
sand and conduct iron removal in a certain reducing atmosphere. High temperature
treatment can effectively remove some impurities, especially iron elements.
Chemical treatment: Metal impurities in quartz sand can be further removed
through acid washing, chlorination, or other chemical methods. Commonly used
chemicals include hydrofluoric acid, hydrochloric acid, etc., which can
effectively remove surface rust and other impurities.
(3) Grading and screening
Using equipment such as vibrating screens and airflow classifiers to grade
high-temperature treated quartz sand, ensuring that quartz sand of different
particle sizes can be used for different industrial applications. The particle
size distribution of high-purity quartz sand should be uniform, and the common
particle size range is usually 0.1-2mm.
(4) Magnetic Separation and Flotation
Magnetic separation: In the production of high-purity quartz sand, magnetic
separation is a common method for removing iron impurities. By using equipment
such as electromagnetic dry powder magnetic separators, iron impurities in
quartz sand can be effectively removed to achieve higher purity.
Flotation: Flotation is used to further remove non silicon minerals such as
metal oxides and clay from quartz sand. The flotation process can help to remove
impurities such as aluminum, sodium, and calcium to a certain extent.
(5) Fine processing
Further process the cleaned and screened quartz sand to ensure that the
particle size and purity meet the requirements. At this time, fine processing
techniques such as ultrasonic cleaning or acid washing are often used to remove
residual impurities.
3. Purity control standards
The purity of high-purity quartz sand is generally required to be above
99.5%, and in some specific applications, the purity requirement is even higher
(such as the purity of quartz sand in the solar and semiconductor industries can
be required to be above 99.9%). Specific standards may vary depending on
different application areas, and common requirements include:
Iron content: The iron content is usually required to be below 0.01%, and in
some high demand applications, the iron content can even reach below 0.001%.
Impurities such as aluminum and calcium: The content of impurities such as
aluminum, calcium, magnesium, and sodium is usually required to be less than
0.05%.
Particle size distribution: The particle size distribution of high-purity
quartz sand requires uniformity, and is usually controlled by grading,
screening, and other methods to meet the needs of different applications.
4. Quality inspection and analysis
The production of high-purity quartz sand requires strict quality testing to
ensure that it meets various standards. Common quality inspection methods
include:
Chemical analysis: Spectral analysis, X-ray fluorescence analysis (XRF) and
other techniques are used to detect the chemical composition of quartz sand and
ensure its purity.
Particle size analysis: Use laser particle size analyzer, sieve analysis and
other methods to determine the particle size of quartz sand, ensuring that the
particle size meets the requirements.
Magnetic testing: Use equipment such as magnetometers to detect the iron
content in quartz sand, ensuring that its magnetic impurities are low.
Moisture content: Check the moisture content of quartz sand to ensure its
dryness.
5. Environmental and Energy Management
Environmental requirements: The production of high-purity quartz sand usually
generates wastewater, exhaust gas, and solid waste, so it needs to comply with
strict environmental standards. Wastewater needs to be treated, and exhaust gas
should be cleaned through dust removal equipment.
Energy conservation and consumption reduction: Due to the high energy
consumption in the high-temperature smelting process, energy-saving measures
need to be taken in the production of quartz sand, such as optimizing furnace
temperature control and utilizing waste heat recovery.
6. Packaging and Storage
High purity quartz sand usually requires special packaging and storage
conditions to prevent moisture and contamination. Usually, moisture-proof and
pollution proof bags and barrels are used for packaging, and stored in dry and
ventilated warehouses.
summary
The production of high-purity quartz sand requires strict selection of raw
materials, refined processing techniques, and efficient quality testing. Through
a series of physical and chemical treatment methods, such as magnetic
separation, acid washing, flotation, high-temperature treatment, etc.,
impurities in quartz sand can be effectively removed to improve its purity and
meet the special requirements of high-end industries for materials. In order to
ensure that the final product achieves the required purity and quality, strict
control is required at every stage of the production process.