Calcium Fluoride, with the chemical formula CaF₂, is an inorganic compound. Below is a detailed introduction to it:
Basic Information
- Molar mass: 78.07 g/mol
- Density: 3.18 g/cm³
- Appearance: Pure calcium fluoride is colorless crystal or white powder. Natural ores are slightly green or purple due to impurities, and sometimes colorless and transparent with a vitreous luster. It is brittle and exhibits prominent fluorescence.
Discovery History
In 1768, Andreas Sigismund Marggraf, a German chemist, studied fluorite and found that it was different from gypsum and barite, concluding that it was not a sulfate. Meanwhile, he discovered hydrofluoric acid. In 1810, André-Marie Ampère, a French physicist and chemist, pointed out that hydrofluoric acid might contain an element similar to chlorine based on his research on its properties. In 1812, Humphry Davy named this element fluorine. In 1886, Henri Moissan, a French chemist, first isolated gaseous fluorine from fluorite and identified the compound as calcium fluoride.
Natural Occurrence
Calcium fluoride exists in nature as the mineral fluorite (fluorspar), which is mainly distributed in China and Mongolia in Asia, Mexico and the United States in North America, South Africa and Kenya in Africa, as well as Spain and France in Europe. Fluorite crystals can take the form of cubes, octahedrons and rhombic dodecahedrons, and its aggregates usually occur in granular or dense massive forms.
Preparation Methods
Laboratory Preparation
It is generally prepared by reacting calcium carbonate with hydrofluoric acid, or treating fluorite powder repeatedly with concentrated hydrochloric acid or hydrofluoric acid.
Industrial Preparation
It can be produced using fluorite as the raw material. Alternatively, direct precipitation is adopted, with calcium nitrate, calcium chloride and calcium hydroxide as calcium sources, and potassium fluoride, sodium fluoride, ammonium fluoride and hydrogen fluoride as fluorine sources.
Application Fields
Metallurgical Industry
It is used as a flux in the metal smelting industry, widely applied in basic open-hearth steelmaking, etc. It is also the most widely used and effective mineralizer in clinker calcination.
Chemical Industry
It is used to produce hydrogen fluoride, hydrofluoric acid, elemental fluorine and various fluorides. Additionally, it serves as the optimal substitute for freon and a catalyst carrier in the preparation of fluorohydrocarbons.
Building Materials Industry
- In the glass manufacturing industry, it acts as a flux to accelerate the melting of glass raw materials.
- In the ceramic manufacturing industry, it is used as a ceramic glaze to enhance color development and melting performance.
- In the cement production industry, it can lower the sintering temperature of furnace charge.
Other Industries
It is being researched for application in dentistry, and is an excellent optical material with extensive uses in optical materials, fluorescent matrix materials and biomaterials. It is also used in the jewelry and craft industries.
Safety Information
Hazards
It has low toxicity but is irritant. Contact with it can irritate the skin and eyes, and severe contact may cause skin corrosion and eye damage. Long-term excessive inhalation can lead to permanent fluorine deposition in bones, resulting in chronic fluorosis.
Emergency Measures
- In case of skin contact: Remove contaminated clothing and rinse the affected area thoroughly with plenty of running water.
- In case of eye contact: Lift the eyelids and rinse with running water or normal saline, then seek medical attention promptly.
Protective Measures
Conduct closed operations with local exhaust ventilation during handling. Wear self-priming filter dust masks, chemical safety goggles, impermeable protective clothing against toxic substances and latex gloves.
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