Phosphate Ore Flotation Process: The Core Technical Approach in Phosphate Mineral Processing

As the most widely applied technique in phosphate ore processing, flotation has become the key to achieving efficient phosphorus resource enrichment due to its adaptability to ores with varying properties. Phosphate ore, one of the primary types of phosphate deposits, primarily consists of calcium phosphate with accompanying gangue minerals such as silicates, carbonates, and iron-aluminum minerals. Characterized by low hardness, moderate density, and acid solubility, its processing difficulty stems mainly from the flotation differences and intergrowth relationships between useful minerals and gangue minerals. Addressing these characteristics, the industry has developed a diversified process system including positive flotation, reverse flotation, positive-reverse flotation, reverse-positive flotation, and double-reverse flotation.

Positive flotation is suitable for colloidal phosphate ore with low magnesium content and fine-grained intergrowth of phosphate minerals and siliceous gangue. This process regulates slurry pH, employs efficient inhibitors to suppress siliceous and carbonate gangue, and utilizes collectors to enhance phosphatic mineral hydrophobicity. Separation relies on mineral flotation differences, proving particularly effective when gangue and phosphatic mineral flotation properties are markedly distinct.

Reverse flotation specifically targets high-magnesium phosphorite containing significant dolomite and calcite. In such ores, calcium ions in gangue minerals narrow the flotation gap between phosphate minerals and gangue, making conventional positive flotation insufficient for optimal separation. Reverse flotation inhibits phosphate minerals with specific inhibitors while using collectors to float carbonate gangue, retaining phosphate concentrate in the tank. Currently, approximately 90% of phosphorite processing plants employ this process for magnesium removal.

Both positive-reverse flotation and reverse-positive flotation are stepwise separation processes. By alternately employing anionic and cationic collectors alongside various inhibitors, they progressively remove silicate, carbonate, and other gangue minerals to yield high-purity phosphate concentrate. This method is suitable for more complex phosphorite ores. Double reverse flotation targets high-silica, high-magnesium mixed phosphorite. Through two reverse flotation stages—using fatty acid collectors and cationic amine collectors to remove carbonate and siliceous gangue respectively—it directly produces qualified phosphate concentrate, achieving efficient separation of complex ores.

These differentiated flotation processes, precisely engineered based on the mineral characteristics and gangue composition of colloidal phosphate ore, provide highly efficient solutions for the resource utilization of various types of colloidal phosphate ore.