How to purify quartz sand?-Sinonine

How to Purify Quartz Sand?

Quartz sand, known as silica sand, is a prevalent non-metallic mineral resource. When treated through beneficiation and purification processes, it can be transformed into high-purity quartz sand, which is extensively utilized in industries such as glass, ceramics, metallurgy, casting, and refractories. So, how can one effectively purify quartz sand? SINONINE stands out as a leader in the field of quartz sand purification and has aided numerous clients in establishing quartz sand washing facilities. Below are the common methods we recommend for purifying quartz sand.

1. Washing, Grading, and Desliming Quartz Sand

The SiO2 grade in quartz decreases alongside the reduction of the size of the quartz particles, leading to an increase in impurity minerals, including iron and aluminum. This issue becomes particularly pronounced in quartz sand rich in clay minerals. Therefore, purifying quartz raw ore through water separation and desliming is crucial. Utilizing hydrocyclones plays a significant role in enhancing the purification effect. As a preliminary treatment in quartz sand purification, washing and grading desliming are commonly implemented across various sand washing plants, marking it as an essential process.

2. Scrubbing Quartz Sand

Scrubbing primarily aims to eliminate thin-film iron, adhering impurities, and mud-like minerals from the surface of quartz sand through mechanical force and abrasive interaction between the sand particles. It furthers the disintegration of non-monomeric mineral aggregates, leading to enhanced purification results through classification processes. Currently, there are two primary techniques for scrubbing quartz sand: rod scrubbing and mechanical scrubbing. In mechanical scrubbing, factors such as the design and configuration of the scrubbing apparatus, scrubbing duration, and concentration also greatly affect the results.

Typically, quartz sand scrubbing works best at a concentration of 50%-60%. Additionally, exhaustive scrubbing might result in excessive wear of the equipment, driving up energy expenses and overall purification costs. For certain types of quartz ores, rod friction washing may also prove beneficial. The introduction of weak acids can help eliminate electrostatic repulsive forces on impurity minerals and quartz particles, thus improving the separation efficacy.

3. Magnetic Separation of Quartz Sand

Magnetic separators are essential for extracting both strong magnetic and weak magnetic impurities such as hematite, limonite, and biotite from quartz sand. Generally, wet magnetic separation techniques are the norm. For instance, a separator functioning with a magnetic field intensity exceeding 1.0T can effectively extract quartz along with weak magnetic impurities. Stronger magnetic minerals like magnetite may require a weak or medium magnetic separator for optimal results.

Research indicates that both the frequency of magnetic separations and the magnetic field strength significantly influence the effectiveness of iron removal. More magnetic separation cycles typically lead to a gradual reduction in iron content, with substantial removal achievable at specific field strengths. Furthermore, a finer quartz sand grain size enhances iron extraction due to the higher prevalence of iron-bearing impurities in smaller grains. It is essential to note that scrubbing, desliming, and magnetic separation alone may not suffice for achieving high-purity sand, especially in heavily contaminated quartz sand.

4. Quartz Sand Flotation

Post scrub and deslime, utilizing flotation techniques can elevate quartz purity to about 99.3%-99.9%, suitable for industrial demands. Flotation processes generally focus on separating feldspar, mica, and other non-magnetic associated impurities from quartz. This involves optimizing the proportion of mixed collectors (cationic and anionic) to prefer floating impurities for separation.

5. Pickling for Further Purification

Pickling leverages the solubility characteristics of impurities in acids, while quartz remains insoluble (except in HF), for enhanced purification. Common acids used in pickling include sulfuric, hydrochloric, nitric, and hydrofluoric acids, while reducing agents like sulfite and its salts play a role as well. These acids show effectiveness against non-metallic quartz impurities, but varying metal impurities require distinct acid types and concentrations for treatment. Generally, dilute acids effectively tackle Fe and Al removal, while Ti and Cr often necessitate strong acids like concentrated sulfuric acid or aqua regia. A mixture of these acids is typically advised for comprehensive mineral removal.

It’s crucial to regulate parameters such as acid concentration, dosage, leaching time, temperature, and mixing to ensure successful purification with minimized processing costs. The aim is always to achieve high-grade purity while controlling operational expenses.

6. Quartz Sand Color Sorting

Color sorting exploits photoelectric technology to differentiate quartz sand from its impurities based on color. This method is mainly applicable to granular materials featuring significant color distinctions, allowing for efficient and fast impurity separation.

In summary, these six purification techniques for quartz sand provide a framework for selecting appropriate methods based on ore characteristics, investment capacities, and desired product grades. Understanding the raw materials is essential before opting for a single or combined processing method through beneficiation testing to maximize economic outcomes.

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