Commonly Used Flotation Agents in Scheelite Beneficiation

Scheelite, a primary source of tungsten, is vital in the manufacturing of high-density alloys, steel, and superalloys. Scheelite beneficiation involves various concentration techniques, with flotation being one of the most widely used methods due to its efficiency and cost-effectiveness. The selection of appropriate flotation agents crucially determines the success of the separation process. This article discusses some commonly used flotation agents in scheelite beneficiation, their mechanisms, and their benefits.

1. Collectors

Fatty Acids and Their Salts

Fatty acids such as oleic acid are prevalent collectors in scheelite flotation due to their strong affinity for the mineral. These fatty acids react with the calcium ions on the scheelite surface, forming hydrophobic layers that aid in flotation. Sodium oleate, a common salt form, is often preferred for its ease of handling and solubility.

Sodium Phosphate

Sodium phosphate is another effective collector for scheelite beneficiation, especially in slightly acidic to neutral pH conditions. It promotes better interaction with the calcium ions present in scheelite, enhancing flotation efficiency.

2. Depressants

Sodium Silicate

Sodium silicate, or water glass, serves as an indispensable depressant in scheelite flotation. It inhibits the flotation of silicate and carbonate gangue minerals, ensuring the selectivity of scheelite. The depressant works by dispersing unwanted minerals, preventing them from adhering to bubbles.

Sodium Carbonate

Sodium carbonate, also known as soda ash, is employed to adjust the pH and acts as a depressant for calcium carbonate and other unwanted minerals. By increasing the pH, sodium carbonate enhances the selective adsorption of collectors on scheelite, making the process more efficient.

3. Frothers

Pine Oil

Pine oil is a widely used frother in scheelite beneficiation. It aids in the formation of stable froths, which are essential for carrying the scheelite particles to the surface. The aromatic compounds in pine oil reduce the surface tension of the liquid, facilitating bubble formation.

Methyl Isobutyl Carbinol (MIBC)

MIBC is another effective frother, renowned for its ability to create persistent froth. This agent improves the flotation process by ensuring the froth does not collapse before the scheelite can be collected, thus increasing recovery rates.

4. Activators

Lead Nitrate

Lead nitrate is used as an activator in scheelite flotation to enhance the absorption of collectors. It reactivates the mineral surfaces, facilitating stronger collector attachment and improving flotation efficiency. However, due to environmental and regulatory concerns, its use is carefully monitored.

Copper Sulfate

Copper sulfate is another activator that is sometimes used to improve the flotation of scheelite. By facilitating the adsorption of collectors on the scheelite surface, it increases the effectiveness of the flotation process.

The successful beneficiation of scheelite via flotation depends significantly on the selection and combination of appropriate flotation agents. Collectors such as fatty acids, depressants like sodium silicate, frothers including pine oil, and activators such as lead nitrate play pivotal roles in ensuring high recovery and purity of scheelite. Understanding the chemical interactions and conditions under which these agents operate best can drastically enhance the efficiency of the beneficiation process.

For optimal results, the industry should continually invest in research and development to discover new, more efficient, and environmentally friendly flotation agents. With the right approach, the flotation of scheelite can be both economically viable and sustainable.