Sedimentary rock type phosphorite flotation process

The useful mineral apatite in collophanite is microcrystalline and cryptocrystalline, without a stable crystal structure. The mineral structure is mostly oolitic and pseudo-oolitic. The mineral embedding particle size is fine, and carbonates and mud minerals such as iron, aluminum and silica are often mixed inside, which makes sorting difficult.

The main methods for sorting collophanite are flotation, scrubbing and desludging, heavy medium beneficiation, magnetic separation, photoelectric sorting, roasting-digestion, chemical leaching, microbial treatment and combined beneficiation process. Among them, flotation is the most widely used process for collophanite.

1. Reverse flotation process

The reverse flotation process is mainly used to separate phosphate and dolomite. Inorganic acid is used as a pH regulator for the slurry. In a weakly acidic medium, a fatty acid collector is used to float out the dolomite. The biggest advantage is that flotation at room temperature is achieved, and the particle size of the tank product is coarse, which is conducive to the post-processing of the product.

2 Direct flotation process

Generally used for selecting low-grade phosphate ore, including processing siliceous and siliceous calcium phosphate ore, as well as calcium and magnesium-containing phosphate ore. This process must be used in conjunction with a strong inhibitor to achieve satisfactory results. It is mainly suitable for ores with fine-grained distribution of phosphate minerals and gangue minerals. In recent years, L series and S series high-efficiency inhibitors have been successfully developed, which can achieve better flotation effects on sedimentary metamorphic apatite, but are only suitable for ores with low Mg0 content, and it is difficult to filter the product directly, which limits the application and promotion of this process in phosphate production.

3 Direct-reverse flotation, reverse-direct flotation

The essence of the direct and reverse flotation process is mixed flotation. First, phosphate minerals and carbonate minerals with similar floatability are mixed and floated by direct flotation, and a large amount of silicate gangue minerals and part of carbonate gangue minerals are excluded. Then, the carbonate minerals are reversely floated on the rough concentrate of direct flotation to reduce the magnesium content of the concentrate and obtain high-quality phosphate concentrate with a low magnesium-phosphorus ratio.

The direct-reverse flotation process and the reverse-direct flotation process have the defects of fine grinding fineness of the original ore, large amount of sodium carbonate and large amount of collector. The double reverse flotation process just meets the flotation principle of "less floating is more", and has the advantages of low reagent dosage and easy dehydration of concentrate.