Fluorite, also known as fluorspar, has a main chemical composition of CaF2, a relative density of 3.0-3.2, a Mohs hardness of 4, brittleness, and a melting point of 1270-1350°C. Fluorite is a common mineral that is widely distributed. Fluorite is widely used as a strategic non-metallic raw material. Fluorite can be divided into three categories according to its grade and use:
(1) Acid-grade fluorspar used in the chemical industry, with a fluorspar mass fraction greater than 97%;
(2) Metallurgical grade fluorspar used for steelmaking and electrolytic aluminum, with a fluorspar mass fraction of 65%-85%;
(3) Ceramic-grade fluorite is used in the building materials industry to make glass and ceramics, with a fluorite mass fraction of 85%-95%. At present, the main consumption structure of fluorspar in China is steelmaking accounting for 13%, aluminum smelting accounting for 8%, fluorine chemical industry accounting for 29%, cement and glass industry accounting for 40%, and others accounting for 10%. Hydrofluoric acid is a key intermediate product for deep chemical processing of fluorite and other fluorine-containing resources and the development of fluorine chemicals. With the rapid development of China’s fluorine chemical industry, more and more acid-grade fluorspar resources will be needed.
According to the different gangue minerals, fluorite ore can be divided into four types, namely quartz-type fluorite ore, carbonate-type fluorite ore, barite-type fluorite ore and sulfide-type fluorite ore.
(1) Quartz-type fluorite ore: The main minerals are fluorite and quartz, and the fluorite content can reach 80% to 90%. Contains small amounts of calcite, barite and sulfide.
(2) Carbonate fluorite ore: the main minerals are fluorite and calcite. The calcite content can reach more than 30%, with a small amount of quartz, sometimes forming a quartz-calcite-fluorite type ore.
(3) Barite-type fluorite ore: The main minerals are barite and fluorite, and the barite content reaches 10% to 40%. This type of ore is often accompanied by sulfides such as pyrite, galena, sphalerite, etc. Sometimes the quartz content increases to form a quartz-barite-fluorite type ore.
(4) Sulfide-type fluorite ore: Its mineral composition is basically the same as quartz-fluorite, but it contains more metal sulfides, and sometimes the lead and zinc content can reach industrial grades. For quartz-type fluorspar ore, the concentrate is mainly used to reduce silicon. For fine-grained quartz-type fluorite ore, oleic acid or oxidized paraffin soap is generally used as the collector, sodium carbonate is used as the pH adjuster of the slurry, and water glass is used as the inhibitor. The stage grinding stage separation process is adopted. After multiple selections, high-quality fluorspar concentrate can be obtained. For carbonate fluorite minerals, since both fluorite and calcite minerals contain calcium ions and their solubilities are similar, there is mutual transformation between the minerals when they coexist in solution, making it difficult to separate fluorite and calcite. . Generally, water glass, salted water glass or acidified water glass is used to inhibit carbonate, oleic acid or other fatty acids as collectors of fluorite; within the pH range of 8 to 9.5, both calcite and fluorite can be collected by oil. For good acid capture, inhibitors need to be used to adjust the difference in the flotability of the two minerals to achieve separation of the two. For barite-type fluorite ore, since barite and fluorite have similar floatability, the separation of fluorite and barite is also a difficulty in the fluorite flotation process. Generally, sodium carbonate is used as the regulator, water glass is used as the gangue inhibitor, and oleic acid is used as the collector. Mixed flotation is used to obtain a mixed concentrate of fluorite and barite, and then the mixed concentrate is flotated with fluorite and barite. separation. There are two methods for separating fluorite and barite: one is to inhibit barite from flotating into fluorite, and the other is to inhibit fluorite from flotating into barite. Research has found that trivalent cations such as Al3+ and Fe3+ have an inhibitory effect on barite and an activating effect on fluorite. On the contrary, divalent barium salts and lead salts can activate barite and inhibit fluorite. For sulfide ore type fluorite ore, use xanthate or black powder to float out the sulfide first, and then use fatty acid collector to float out the fluorite concentrate.
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