Introduction to the Process Flow of Quartz Sand Beneficiation

Quartz sand purification is a highly challenging separation technique aimed at removing trace or minimal impurities from quartz sand to produce refined quartz sand or high-purity quartz sand. The primary quartz sand purification processes employed domestically and internationally include water washing, graded desliming, scrubbing, magnetic separation, flotation, acid leaching, and microbial leaching.

1. Water Washing and Graded Desliming  

The SiO₂ content in quartz sand decreases as the particle size becomes finer, while the content of impurity minerals increases. This phenomenon is particularly pronounced in quartz sand containing a large amount of clay-like minerals. Therefore, it is essential to perform water washing and desliming on the raw quartz sand ore before processing.

2. Scrubbing  

Scrubbing utilises mechanical force and abrasive force between sand particles to remove thin-film iron and clay-like impurity minerals from the surface of quartz sand, as well as further crush mineral aggregates that have not yet formed individual particles. This is followed by classification to achieve further purification of the quartz sand. Currently, there are two main methods: rod mill scrubbing and mechanical scrubbing.

3. Flotation

Separating mica from quartz is challenging. Flotation using anionic collectors under acidic conditions or mixed anionic-cationic collectors under alkaline conditions can achieve excellent results. Generally, after scrubbing, desliming, magnetic separation, and flotation, the purity of quartz sand can reach over 99%, meeting the requirements for industrial sand.

4. Acid Leaching

Dilute acid effectively removes iron and aluminium, while titanium and chromium are removed using concentrated sulphuric acid or aqua regia for acid leaching. Typically, a mixture of these acids is used to leach out impurity minerals. The control of various factors in acid leaching should be based on the required final quartz grade, aiming to minimise acid concentration, temperature, and usage to achieve quartz purification at lower processing costs.

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