The main processing methods for phosphate tailings include five techniques: gravity separation, magnetic separation, flotation, acid leaching, and alkali leaching.
Gravity separation is employed to separate phosphate minerals from other gangue minerals or impurities, such as sand and clay, during the re-selection of phosphate tailings.
Prior to gravity separation, the tailings may undergo pre-processing, such as screening or crushing, to ensure that particle sizes are suitable for separation operations.
During gravity separation, particles are separated based on differences in density induced by gravity. Phosphate minerals tend to settle at the bottom, while lightweight materials like sand and clay float to the surface. In practical applications, it may be necessary to combine other separation methods, such as magnetic separation or flotation, to achieve optimal recovery.
Magnetic separation is a suitable method for removing iron if it is present in phosphate tailings.
The phosphate tailings are first ground to ensure effective magnetic separation. Magnetic separation equipment is then used for the separation process.
During separation, magnetic field intensity, rotation speed, and feed rate are adjusted based on the properties of tailings and magnetic materials to avoid affecting separation efficiency.
Flotation is a widely used method in ore processing, utilizing bubbles to float valuable minerals to the liquid surface for collection. In the treatment of phosphate ore tailings, flotation can be used to separate phosphate minerals.
Acid leaching involves immersing tailings in an acidic solution to dissolve phosphate minerals. This process allows the extraction of phosphate minerals from tailings, forming a phosphate leachate.
The phosphate minerals can be separated from the leachate through precipitation or other methods.
Alkali leaching is a method that uses an alkaline solution, typically employed for separating materials containing aluminum. The alkaline solution converts aluminum minerals into soluble salts.
Through alkali leaching, aluminum minerals can be dissolved from tailings, and subsequent separation of aluminum salts can be achieved through precipitation or other methods. Sodium hydroxide or potassium hydroxide is commonly used as the alkaline solution for alkali leaching.
