【Fluorite Flotation Process】How to Separate Fluorite from Quartz, Calcite, Barite and Sulfide?

In the field of ore processing, the flotation process of fluorite ore has become a key research direction due to its complex mineral structure and separation requirements. According to the main components in the ore, fluorite ore can be divided into four types: quartz, calcite, barite and sulfide. Each type significantly differs in flotation processes due to different mineral characteristics and distribution forms. This article will delve into the flotation process of various types of fluorspar ores, including key links such as reagent selection, slurry adjustment, grinding process, and silicon reduction in concentrates, to help readers better understand and apply these processes.

1. Flotation Process of Quartz-Fluorite Type Ore

Quartz-fluorite ore is mainly composed of fluorite (content up to about 85%) and quartz, with only a small amount of calcite, barite and sulfide. The key to separation is mainly to reduce the silicon content of the concentrate. To separate quartz from fluorite, quartz and fluorite monomers must be dissociated by grinding, so grinding is an important factor affecting the flotation of quartz-fluorite. In production, quartz-fluorite-type ores are mostly ground for rough selection once, and the rough concentrate is re-grinded for multiple processes. The reagent system often adopts sodium carbonate as an adjusting agent and is adjusted to alkaline to prevent the activation of multivalent cations in water on quartz. When using fatty acids as collectors, an appropriate amount of water glass is added to inhibit silicate gangue minerals, and the amount of water glass is controlled (a small amount can activate fluorite, and an excessive amount will inhibit fluorite). According to the characteristics of useful mineral dissemination, quartz-fluorite ores can be divided into two types: coarse-grained and fine-grained dissemination and the two types have different flotation separation process flows.

Coarse-grained fluorite is easy to select. By using fatty acid collectors, sodium carbonate as pulp adjuster, and water glass as quartz depressant, high-quality fluorite concentrate can be obtained through a one-coarse-multiple-fine process. The flotation reagents for fine-grained quartz-type fluorite are the same as those for coarse-grained quartz-type fluorite. Because the target mineral has a finer particle size, it is necessary to strengthen the grinding process and adopt a stage-grinding and stage-separation process.

2. Flotation Process of Calcite-Fluorite Type Ore

The main minerals of calcite-fluorite type ore are fluorite and calcite (content up to 30% or more), some of which contain a small amount of quartz, and sometimes form quartz-calcite-fluorite type ore, which is a difficult ore to separate.

The main reason why this type of ore is difficult to separate is that calcite and fluorite are both calcium-containing minerals with similar surface physical and chemical properties. When they coexist in solution, it is easy for the minerals to transform into each other. The key to separating fluorite and calcite is to select suitable collectors and inhibitors.

To achieve the separation of calcite and fluorite, the pH value of the slurry must be adjusted, and then a collector can be used to achieve a good separation effect. When the pH value is 8 to 9.5, water glass, acidified water glass, sodium hexametaphosphate, lignin sulfonate, dextrin, and tannin are used alone or in combination to inhibit calcite, thereby achieving the purpose of separation. In addition, for more complex fluorite ores containing more calcite, limestone, dolomite, tannin extract and lignin sulfonate can be used to inhibit gangue minerals, and their flotation separation effect is better.

3. Flotation Process of Barite-Fluorite Type Ore

The main minerals of barite-fluorite ore are barite and fluorite. The barite content is generally 10%-40%, often accompanied by pyrite, galena, sphalerite and other sulfide minerals.

This type of ore beneficiation generally first mixes and floats to obtain barite-fluorite mixed concentrate, and then separates barite from fluorite. According to the order of floating of barite and fluorite, it can be divided into two schemes: one is to suppress the flotation of fluorite by barite, which can obtain high-grade barite concentrate and fluorite concentrate, the other is to suppress the flotation of barite by fluorite, which first obtains barite concentrate, adds fatty acid collectors and sodium silicate to the tailings, and selects fluorite concentrate multiple times (7~9 times).

This method has a simple process and is easy to operate. It can obtain qualified barite concentrate, but the grade of fluorite is often not high.

In actual production, the separation of fluorite and barite mostly adopts the process of floating fluorite to suppress barite, with fatty acid flotation agents as fluorite collectors, and organic inhibitors such as caustic starch and dextrin are used in combination with inorganic inhibitors such as sodium hexametaphosphate, sodium fluorosilicate, water glass, aluminum salts, and iron salts to achieve the purpose of separating fluorite from barite.

4. Flotation Process of Sulfide Fluorite Ore

In actual production, the sulfide fluorite ore beneficiation technology is mainly based on flotation. The sulfide ore is first floated out with a xanthate collector. The fluorite tailings are treated as fluorite ore separately and are repeatedly selected with fatty acid reagents. Sometimes, in the fluorite flotation operation, a small amount of sulfide ore inhibitor (such as cyanide) is added to suppress the residual sulfide to ensure the quality of the fluorite concentrate.

In addition, roasting, leaching and other beneficiation technologies can also be used to extract valuable metals and decompose fluorite. The process flow is relatively simple and can prepare high-quality fluorite products while comprehensively recycling valuable metals.

In general, fluorite ore types such as quartz, calcite, barite, and sulfide each have their own unique flotation processes. In actual production, rational selection of the flotation process, optimization of the chemical system, and precise control of slurry adjustment are the keys to achieving high-quality fluorspar concentrate. Mastering the corresponding process technologies for different types of fluorspar ores will greatly improve the ore separation effect and economic value, and bring significant gains to mining companies.