What are the flotation methods of zircon?

The main chemical component of zircon is zirconium silicate, which has a high zircon content. At the same time, it may also contain a small amount of radioactive elements such as hafnium, thorium, uranium, and impurities such as iron, calcium, and magnesium. Zircon is an important raw material for manufacturing advanced ceramics. It has the characteristics of high temperature resistance and corrosion resistance. However, in the process of mineral processing and purification, in order to improve the grade of zircon, it needs to be purified. Let's learn about the types of zircon flotation methods.

1. Zircon flotation method

1. Fatty acid collector flotation method

Fatty acid collector flotation method mainly utilizes the physical and chemical effects of fatty acid compounds and the surface of zircon. Fatty acids (such as oleic acid, linoleic acid, etc.) will dissociate in the slurry, and their anion part can react chemically with metal ions (zirconium ions, etc.) on the surface of zircon to form chemical bonds or chemical adsorption. This adsorption changes the hydrophilicity of the zircon surface into hydrophobicity. At the same time, after adding a foaming agent to the slurry to generate bubbles, the hydrophobic zircon particles can attach to the bubbles and float to the surface of the slurry with the bubbles, thereby separating from the gangue minerals remaining in the slurry.

The selectivity of fatty acid collectors is relatively poor. It can not only react with zircon, but also with some gangue minerals (such as some calcium and magnesium-containing minerals), resulting in more impurities in the concentrate, affecting the further improvement of the concentrate grade.

This type of collector may solidify or become less soluble at low temperatures, affecting its dispersion in the slurry and its effect on the mineral. Therefore, the slurry may need to be heated in a low temperature environment, which will increase energy consumption and production costs.

2. Amine collector flotation method

The amine collector flotation method is mainly based on the ionization and adsorption of amine compounds in alkaline slurry. Under alkaline conditions, amine collectors (such as dodecylamine, etc.) will ionize to form cations. These cations can be adsorbed on the surface of zircon, making the surface of zircon positively charged, thereby making it hydrophobic. Unlike fatty acid collectors, amine collectors mainly change the surface properties of zircon through electrostatic adsorption and other effects. When there are bubbles in the slurry, the hydrophobic zircon particles can float up and be separated from the gangue minerals.

Amine collectors have good selectivity for zircon, especially when processing ores containing more gangue minerals such as quartz, they can effectively inhibit the flotation of gangue minerals and improve the grade of zircon concentrate. This type of collector has relatively stable performance at room temperature and does not need to be heated at low temperature like fatty acid collectors, so the operation is relatively simple.

3. Phosphonic acid collector flotation method

Phosphonic acid collector flotation method uses the chemical reaction between phosphonic acid compounds and the surface of zircon. Phosphonic acid collectors (such as styrenephosphonic acid, etc.) contain phosphonic acid groups in their molecules, which can react chemically with zircon ions on the surface of zircon to form stable chemical bonds. This chemical bonding changes the properties of the zircon surface from hydrophilic to hydrophobic. After bubbles are generated in the slurry, zircon particles can attach to the bubbles and float with the bubbles, thereby achieving separation from the gangue minerals.

Phosphonic acid collectors have high selectivity for zircon and can effectively react chemically with the zircon surface to reduce non-selective adsorption with gangue minerals, thereby obtaining a higher-grade zircon concentrate. This collector has relatively stable performance in a wide pH range and is highly adaptable to flotation conditions, which can simplify the control of the flotation process to a certain extent.

However, the cost of phosphonic acid collectors is high, which is a major limiting factor in their application. The synthesis process of some phosphonic acid collectors is relatively complex and the production scale is limited, which may affect the stability and cost of their supply.

2. Zircon flotation process

When zircon is beneficiated, no matter which flotation method is used, the principle process basically follows the grinding, slurry mixing, dosing, and flotation.

1. Zircon crushing and grinding process

The raw ore is first crushed and ground to dissociate the zircon as much as possible. The grinding fineness generally requires that the content of -0.074mm accounts for about 70%-80%. If the grinding fineness is not enough, the zircon and the gangue minerals are not fully dissociated, which will affect the flotation effect; and excessive grinding may cause mineral mud, which will also have an adverse effect on flotation. Usually, the equipment required for this process is mainly crushers and ball mill equipment.

2. Zirconite slurry adjustment process

The slurry after grinding needs to be adjusted. Adjusting the pH value of the slurry is a key step. Generally, the pH value is controlled between 8-10. In this pH range, fatty acid collectors can play a better role. Alkaline regulators such as sodium carbonate are usually used to adjust the pH value. At the same time, in order to inhibit the flotation of gangue minerals, some inhibitors such as water glass are added. Water glass can be adsorbed on the surface of gangue minerals to keep them hydrophilic, thereby reducing the floating of gangue minerals.

3. Zircon dosing steps

Fatty acid collectors are added, and the dosage is generally determined according to the properties of the ore and the flotation test, usually ranging from several hundred grams to several thousand grams per ton of ore. The collector should be added to the slurry evenly, and proper stirring is required to ensure that the collector can fully contact the surface of the zircon. Then add a frother to produce stable bubbles to provide a carrier for the floating of zircon.

4. Zircon flotation process

Roughing: The slurry that has been adjusted and doped with drugs is sent to the flotation tank for roughing. Under the action of aeration and stirring, zircon particles adhere to the bubbles and float to the surface of the slurry to form a foam layer. The foam layer is scraped off to obtain a crude zircon concentrate, while the part left in the slurry is the tailings. The purpose of roughing is to preliminarily separate zircon and gangue minerals.

Concentration:The grade of zircon concentrate obtained by roughing may not be high enough and needs to be refined. Concentration is to further purify the crude zircon concentrate in a new flotation tank, and reduce the content of gangue minerals and improve the grade of the concentrate by adjusting the dosage of reagents and other conditions. Concentration may be carried out multiple times until the desired concentrate grade is reached.

Scavenging:Scavenging is to refloat the tailings to recover the remaining zircon and improve the recovery rate. During scavenging, it may be necessary to appropriately adjust the dosage of reagents and flotation conditions, because the zircon content in the tailings is relatively low, and its surface properties and flotation environment may be different from those during roughing.

The above is an introduction to the process and process of zircon flotation beneficiation. In actual beneficiation plants, although flotation is the main beneficiation method, it depends on the properties of zircon ore. Therefore, it is recommended to conduct ore dressing tests first, and design suitable process methods through test analysis to obtain ideal recovery rates.