Research and Application of Flotation Separation Technology for Fluorite Ore

Fluorite (CaF₂), as a critical fluorine-containing industrial mineral, is widely used in metallurgy, chemical engineering, and construction. With the gradual depletion of high-grade fluorite resources, efficient separation of complex symbiotic fluorite ores has become a technical challenge. Flotation, due to its adaptability and efficiency, remains the core process for fluorite separation. This article focuses on flotation methods for separating fluorite from common associated minerals such as quartz, calcite, and barite.

1. Separation of Fluorite and Quartz

In quartz-fluorite ores, quartz often coexists with fluorite as silicates. Flotation requires优先抑制石英, primarily using sodium carbonate to adjust the pulp to alkaline conditions (pH=8-9), preventing polyvalent cations from activating quartz surfaces. Sodium silicate (water glass) is added to inhibit silicate minerals. Fatty acid collectors (e.g., oleic acid) are commonly used. A process of coarse grinding followed by regrinding and multiple cleaning stages ensures fluorite enrichment. Studies show that grinding fineness must achieve monomer dissociation of quartz and fluorite. For instance, a Hunan fluorite ore achieved a concentrate with 97.5% CaF₂ grade and 80.97% recovery through staged grinding (-0.074 mm, 97.48%) and nine cleaning steps.

2. Separation of Fluorite and Calcite

Calcite (CaCO₃) shares similar surface calcium ion activity with fluorite, making their separation challenging. A common approach involves mixed flotation followed by selective calcite depression. Combined depressants such as sodium silicate + sodium hexametaphosphate or lignin sulfonate + dextrin are used to reduce collector adsorption on calcite. Modified sodium silicate (NSOH), with its colloidal silicic acid (SiO₂(OH)₂²⁻), effectively inhibits calcite. For example, a study using oleic acid with NCR/TT modifiers achieved 97% recovery in roughing, while NA/TH depressants suppressed over 50% of calcite in cleaning. Novel collector H06, leveraging steric hindrance, improved selectivity by 24% compared to oleic acid.

3. Separation of Fluorite and Barite

Fluorite and barite (BaSO₄) exhibit similar floatability, necessitating tailored reagent regimes:

1. Preferential Fluorite Flotation: Sodium silicate + NaCl      depress barite, while oleic acid floats fluorite. The SDF depressant      (Na₂SO₄ + caustic starch) enhances barite depression, yielding a      concentrate with 95.6% CaF₂ grade and 98.3% recovery in a single roughing      stage.

2. Mixed Flotation-Separation: Co-flotation followed      by selective depression. For instance, citric acid + iron salts depress      fluorite, allowing alkyl sulfonate to float barite. An Inner Mongolia      fluorite ore achieved 96.28% CaF₂ grade using dextrin as a depressant.

4. Technical Challenges and Innovations

1. Silica Reduction: Controlling grinding fineness is key to      reducing SiO₂ content below 1%. Acidic sodium silicate combined with H101      depressant successfully lowered SiO₂ to 0.5%.

2. Novel Collectors: The W-series collectors, tolerant to low      temperatures, improved recovery by 2%-5% in Shandong and Inner Mongolia.      GY-2, derived from petroleum byproducts, achieved 98.34% CaF₂ grade at 600      g/t dosage.

5. Conclusion

Fluorite flotation separation requires customized processes based on ore types, with combined depressants and high-efficiency collectors being pivotal. Future efforts should focus on utilizing symbiotic resources, studying reagent mechanisms, and advancing low-temperature and eco-friendly technologies to address resource scarcity and environmental demands.