Some Aspects about Fluorite Beneficiation Technology
2019-06-28 19:03:54xinhai
Fluorite is one of common non-metal minerals, also called fluor. The main component of fluoriteis CaF2, so fluorite is the industry resource of F. Fluorite has rich color. Fluorite usually grows with scheelite, phosphorite, pyrite, blende, quartz, dolomite and other minerals. Flotation separation is difficult for similar characteristics between fluorite and pyrite, barite.
It was born from volcanic magmas. During the cooling period, there are many materials in the gas water solution from the magmas. The main material is fluorine. The temperature and pressure decreased when the solution rises in the cracks. Since that, the fluorine combines with the calcium ion from surrounded stones into calcium fluoride, which make up the fluorite after cooling. The pure calcium fluoride is without color. However, because of the special structure of fluorite, other ion can get mixed into it easily. So there is few colorless and transparent fluorite in nature and fluorite is the most colorful stone in the world. The natural fluorite is bright and colorful, which is known as ‘the rainbow gem’.
Fluorite, with rich color and glittering structure, is the main source of fluorine in industry. It has both appearance and value
The main producing area of fluorite is China, Africa, Mongolia, Russia, America,Thailand, Spain and other countries. China is one of the countries with the largest number of fluorite minerals in the world. There is a saying that: “World fluorite in China, China fluorite in Zhejiang, Zhejiang fluorite in Jinhua, Jinhua fluorite in Wuyi.” We could know the large reserve of fluorite in China through this saying.
Fluorite is widely useful. It can be made into hydrofluoric acid and further into kryocide. The hydrofluoric acid is widely used in aluminium industry, aerospace industry, atomic energy industry, pharmaceutical fields, Inorganic fluorination industry, and building materials industry. Because of the abundant color, the fluorite used to be the decoration of the Hemudu people. Some fluorite can even shine itself, which is also known as the legendary luminous pearl. Fluorite can also be used in fluorescent pigment for its speciality.
It is chose the suitable dressing technology for fluorite through the row ore sliming rate, the impure minerals degree of symbiosis with fluorite, and the ore characteristics. Ordinarily, Fluorite is suitable for gravity separation and flotation separation. Xinhai thinks that jig could be used in the gravity separation for the crude fluorite lump ore.
Fluorite usually inter-grows with sulphide ore, barite and quartz. Xinhai chooses suitable flotation technology to deal with the fluorite with sulphide ore. Xanthogenate as a collector first float the sulphide and then add collector of fatty acid in the pulp to float fluorite. We can also add a small amount of sulfide mineral inhibitors to inhibit the rudimental sulphide, which can make sure the quality of fine fluorite ore. Xinhai chooses bulk flotation technology to deal with the fluorite with barite. The oleic acid can be used as collectors here. The bulk concentrate can be separated through direct flotation and reverse flotation into fluorite concentrate. Xinhai chooses fatty acid to capture fluorite when dealing with the fluorite with quartz. Water glass is used to restrain the quartz. The volume of the water glass need to be controlled. A small amount can activate fluorite, but not restrain quartz. While too much of water glass would restrain fluorite. Some polyvalent metal ions can be used to increase the restraining effort of water glass. It also can be used for calcite.
Pyrite and fluorite can be captured by fatty acid collector and both Calcium minerals.It is difficult to separate them through flotation.
At the question in researching the separation of fluorite and pyrite, the key point is how to increase the floating difference of them. Under alkaline condition, pyrite has a good floating condition, while under weak acid condition, pyrite is more difficult to separate. However, fluorite is similar under these two condition. So pH can be controlled to increase the float difference, so that fluorite and pyrite can easily separate. The pH in fine separation should be controlled from 6.4 to 6.8 according to experiment data.
On the basis adjusting pH, pyrite inhibitor can be added to inhibit pyrite. Pyrite is carbonate mineral, so common agent assembly includes:
1. Tanninextract as pyrite inhibitor, 731 as fluorite collector.
2. Acidsodium silicate as pyrite inhibitor dealing with raw ore, and using fatty acid as collector.
3. Using water glass, caustic starch and sodium hexametaphosphate as mixed inhibitor, saponificationoleic acid as collector for coarse flotation, and using water glass and citricacid as mixed inhibitor for concentrating flotation.
There are many types of agent assemblies.
Similar to the idea of separating fluorite and calcite, barite is mainly composed of barium sulfate. These two mineral components are quite different from each other, with different pharmaceutical combinations and different pH requirements. Therefore,each group of agents has its corresponding appropriate pH range. Taking a group of common agents as an example, fluorite recovery is much higher than barite ata pH of around 5.9 with barium sulfate as an inhibitor. Therefore, under this condition, a combination of naphthenic acid as a collector can be used to separate fluorite and barite.
In addition to this pair of pharmaceutical combinations, common combinations used to separate fluorite and barite include:
1. Sodiumsulfate and caustic starch were used as mixed inhibitors. Tf 2-8 sequence collector was used. Barite was treated at a pH value of about 8.5.
2. Separation of fluorite and barite with selective oxidized paraffin soap and nitroalkyl propylenediamine as a mixed collector.
To summarize the separation technology of barite and fluorite, the preferential flotation process can be used to suppress the fluorite flotation scheme of barite and other minerals at the time of purchase, the first flotation scheme of barite and then flotation scheme of fluorite, and the mixed flotation and separation scheme.
Sodium carbonate, sodium silicate and oleic acid are commonly used for flotation of barite and fluorite, followed by fluorite sulfonate, sodium fluoride, sodiumsilicate, aluminum salt, iron salt and dextrin to inhibit barite and other minerals, and fluorite is flotation with oleic acid. The selection of agents is more, it is suggested to carry out mineral processing test, according to different minerals to choose the appropriate process and agent system.
Fluorite and quartz are mostly symbiotic, and the removal of quartz is mainly determined according to different product grades. Fluorite concentrates generally have three grades: metallurgical grade, ceramic grade and acid grade. Acid grade requires higher silicon content in concentrates.
In order to separate fluorite and quartz as much as possible, it is necessary to start from the grinding, through which fluorite and quartz monomer are separated. The problem in this process is that the grinding granularity is too coarse, resulting in the products still containing fluorite and quartz intersections. If the grinding particle size is too fine, it will lead to fluorite too crushing and difficult to recover. Usually, in order to separate fluorite and quartz monomer and recover fluorite effectively, a stage grinding flotation process can be used for separation.
In the case of small concentrate production in small mines and inconvenient for regrinding, the method of rod grinding can be adopted. The uniform grinding particle size of rod mill can effectively reduce the occurrence of over-crushing and significantly reduce the silicon content of fluorite concentrate.
A fluorite mine in Hebei has a low ore grade and a high degree of oxidation. The fluorite grain size is fine and it has a low hardness. The original technology is a fine separation with grinding, and seven separation. The concentration grade of fluorite was 88%, while the recovery rate was just 75.66%. The dressing index was seriously influenced the production index and financial efficiency. Xinhai was delegated for the technology update. Through the dressing test, Xinhai improved the flotation stage and adjusted the inhibitor. After the update, the grade and recovery rate increased obviously in production.