Calcium and fluorine combine to form fluorite, a crucial industrial mineral (CaF2). It has several applications in the fields of chemistry, metalworking, and ceramics. Crystal clarity and vivid color in a specimen are sought after for usage in jewelry and decorative items.
Veins are the site of fluorite deposition due to hydrothermal processes. It is common for this mineral to be found in these rocks as a byproduct of metal extraction. Some dolomites and limestones also contain fluorite in their cavities and cracks. It is a mineral that forms rocks and can be found in many different environments. The term “fluorspar” is commonly used to refer to fluorite in the mining sector.
CaF2 (calcium fluoride) is the mineral form of fluorspar. Both the European Union and the United States designate it as a key mineral because of its importance in industrial production. The two most popular forms of this mineral are acid-spar grade and met-spar grade, and they are used extensively in the production of steel, aluminum, and chemicals.
When fluorspar crystallizes, it typically forms regular cubic crystals that can take on a rainbow of hues. For its low melting point, fluorspar is useful as a flux in smelting because it increases the fluidity of metallurgical slags at lower temperatures. It is also widely utilized in the production of hydrofluoric acid and is the primary industrial source of the element fluorine. In the commercial sector, fluorspar is separated into acid-grade, metallurgical-grade, and ceramic-grade categories based on quality and specification.
Fluorspar deposits can be located in a variety of geological settings across every continent. The majority of fluorspar is formed when hydrothermal5 solutions are deposited from either igneous intrusions or deep diagenetic6 processes. Veins and replacement deposits are formed when minerals flow into and out of cracks and crevices in the rock, or when the mineralization completely replaces the host rock (which is usually composed of carbonates). As an accessory mineral, fluorspar is also found in igneous rocks, namely in association with pegmatitic granites, where deposits have been proven to be economically viable.
Both underground and open-pit techniques are used to extract fluorspar. When veins are either easily accessible at the surface or may be found at relatively shallow depths (less than 100 meters), open-pit mining techniques are used. Mining occurs underground at greater depths. Shrinkage stopping, also known as sub-level stopping, uses shattered ore to support the stope15 walls; room and pillar mining, on the other hand, uses ‘pillars’ of rock that are left in place to support the excavation.
To ensure a consistent feed grade to the beneficiation16 facility, fluorspar ores are typically mixed before use. Most ores require crushing, washing, and screening before processing, while exceptionally high-grade fluorspar can be exported immediately from the screening stage. These days, gravity and froth flotation are typically used together in beneficiation plants. The gangue17 minerals are removed by liquid gravity concentration to yield either coarse metallurgical grade fluorspar or feed for a flotation operation that generates acid or ceramic grade fluorspar. Ore is coarsely crushed to release impurities before being delivered into tanks of agitated chemical solution during the flotation process.
Froth forms as the fluorspar grains preferentially adhere to the rising bubbles in the tank. Concentrates of inferior quality may be generated alongside the better quality concentrate in specific circumstances. Concentrates with lesser purity levels are used to make ceramics or pelletized into metallurgical fluorspar. This is because there is a greater need for acid grade fluorspar. Mexichem, a Mexican fluorspar company, is working on a method to enable the manufacturing of hydrofluoric acid from high-arsenic fluorspar (a common impurity). Consequently, the number of mineral formations from which acid grade fluorspar may be extracted may increase.
The final application of fluorspar is dependent on its grade. Almost two-thirds of global production goes into making hydrofluoric acid, which is used in numerous chemical processes. Approximately one-third of all fluorspar mined is of metallurgical quality, and this kind is generally put to use as a flux in steelmaking and the aluminum industry. Only a small fraction of mined fluorspar is of ceramic quality, and this is what goes into making things like dark colored glass and enamels.
Aluminum, gasoline, insulating foams, refrigerants, steel, and uranium fuel are just few of the many goods that employ fluorspar in some capacity. However, the production of fluorosilicic acid as a byproduct by some phosphoric acid companies serves as a supplementary domestic source of fluorine that is not factored into estimates of either fluorspar production or consumption.
In the last ten years, new applications for fluorine have evolved in the form of fluoropolymers in the plastics and electronic industries, which may help to offset the demand decline caused by the decline in CFC manufacturing. The exceptional properties of fluoropolymers (such the widely used PTFE resin) include resistance to heat and flame, resistance to chemicals, excellent electrical insulation, and a very low coefficient of friction. This has led to an explosion of products and uses, for which new markets are constantly being created. Ethylene tetrafluoroethylene, also known as Fluon, is used in architecture as a replacement for glass because it is stronger, cheaper, and transmits more light, while PTFE is used to create a non-stick coating on frying pans; polyvinylidene fluoride (PVDF) can be used for high-specification paints due to its high resistance and color retention.