Collophanite is a phosphate mineral, a common name for low-grade sedimentary phosphorite, which is often cemented with dolomite carbonates, silicon materials, mud minerals and other fine particles. Since collophanite is often characterized by "poor, fine and impure" and has a high silicon and magnesium content, it is difficult to separate. Flotation technology is commonly used for collophanite beneficiation, or flotation combined with other processes.
(1)Positive flotation process
The positive flotation process is to add a specific inhibitor to the monomer-dissociated slurry to inhibit the gangue minerals, and then add a specific collector to make the collophanite hydrophobic. Phosphate minerals are separated by flotation under the action of a frother. This method is mainly suitable for medium-siliceous phosphate ore and sedimentary metamorphic siliceous-calcium apatite.
However, it is difficult to separate calcium-siliceous phosphorite with high carbonate gangue minerals. The foam viscosity is high during flotation, the concentrate is difficult to settle, and the content of impurities such as calcium and magnesium is too high.
(2)Reverse flotation process
The reverse flotation process uses sulfuric acid or phosphoric acid as a slurry pH adjuster and a phosphate mineral inhibitor, and uses a cationic collector to float silicate gangue minerals into the foam product in a weakly acidic medium to obtain a phosphate concentrate product in the flotation tank. It is mostly suitable for the flotation separation of aluminum silicate ores such as quartz, feldspar and non-ferrous metal oxide ores.
(3)Direct-reverse flotation process
The direct-reverse flotation process is to first use anionic collectors and gangue mineral inhibitors to directly float out phosphate minerals, and then use cationic collectors and silicate inhibitors to reversely float silicate minerals (MgO impurities) from phosphate concentrate. The product in the tank is phosphate concentrate. It is mainly suitable for processing calcium-magnesium mixed collophanite with high silicate content.
(4)Reverse-direct flotation process
The reverse-direct flotation process is: first use cationic collectors and silicate mineral inhibitors to reverse float out silicate minerals, and then use anionic collectors and silicate gangue mineral inhibitors to directly float out phosphate minerals. It is suitable for mixed collophanite with high carbonate content.
(5)Double reverse flotation process
The principle of double reverse flotation process is: fatty acid salt is used as the collector of carbonate reverse flotation to enrich dolomite gangue minerals in the foam, and then cationic collector is used as the collector of siliceous mineral reverse flotation to enrich quartz gangue minerals, and finally the phosphate concentrate is left in the tank. It is mostly suitable for processing high-silicon-magnesium mixed phosphorite.
For some minerals that are difficult to obtain qualified concentrates through a single flotation method, a combined separation process can also be used. Commonly used combined beneficiation processes are:
(1)Gravity separation-flotation combined process
Using the density difference between useful minerals and gangue minerals for gravity pre-selection, reducing the amount of ore entering the flotation operation, not only can better phosphate concentrate indicators be obtained, but also to a certain extent reduce the beneficiation cost.
(2)Magnetic separation-flotation combined process
First, the magnetic minerals are separated by magnetic separation, and then flotation is performed to further improve the concentrate quality.
(3)Roasting-magnetic separation combined process
First roast the ore to change the physical and chemical properties of the mineral, and then separate the useful minerals through magnetic separation. For example, after the high-phosphorus limonite is subjected to magnetic reduction roasting and then magnetic separation, better iron concentrate indicators can be obtained while reducing the phosphorus content.
(4)Roasting-magnetic separation and flocculation combined process
Combining the advantages of roasting, magnetic separation and flocculation, it can more effectively separate useful minerals from gangue minerals.
It is necessary to conduct mineral processing tests first to scientifically customize the appropriate mineral processing process. It is important to scientifically and reasonably customize the appropriate mineral processing process through the test results, because different ore properties and mineral processing requirements require different combined processes to achieve better mineral processing effects.
