Minerals fluorite

Using the density of calcium fluoride (CaF2, found in nature as the mineral fluorite), which is known to be... 

No compound containing a halogen other than chlorine appears among the top 50 industrial chemicals, but fluorine nevertheless has considerable commercial value. Fluorine occurs as the mineral fluorite (CaF2) and is prevalent in phosphate-bearing rock. As already mentioned, HF produced from sulfiaric acid treatment of fluorite supplies some 70% of industrial HF the remainder comes as a by-product of phosphoric acid production. 

Figure 13-5 (a) Crystals of the mineral fluorite, CaF2. (fc>) Each Ca24 ion is surrounded by eight F ions at the corners of a cube. Each F ion is surrounded by four Ca2 ions at the corners of a tetrahedron. If you imagine the next unit cell above this one, you should see that the Ca2 ion at the center of the top face of the cell shown here is adjacent to four F ions in this cell and four F ions in the next cell above it. 

The mineral fluorite, CaF2, in Figure 13-5 has a cubic crystal structure and often cleaves to form nearly perfect octahedra (eight-sided solids with equilateral triangular faces). Depending on impurities, the mineral takes on a variety of colors and may fluoresce when irradiated with an ultraviolet lamp. 

Using the density of calcium fluoride (CaF2, found in nature as the mineral fluorite), which is known to be 3.180 g-cm-3, and the information given in Exercise 5.34, calculate (a) the edge length a of the unit cell and (b) the Ca-F separation in fluorite. 

The mineral fluorite (CaF2) has the same 3 3PTT structure but with the roles of cations and anions reversed. Because CaF2 is more com-... 

Fluorine occurs in nature in the form of the minerals fluorite, CaF2, cryolite, Na3AlF6, and fluoroapatite, Ca5(P04)3F, and one commercial source of natural cryolite is Greenland. Both of the other minerals are widespread in nature, although the major use of fluoroapatite is in the production of fertilizers, not as a primary source of fluorine. Extensive fluorite deposits are found in Southeastern Illinois and Northwestern Kentucky. From the standpoint of fluorine utilization, both cryolite and fluorite are extremely important minerals. Cryolite is used as the electrolyte in the electrochemical production of aluminum from bauxite, and fluorite is used as a flux in making steel. Today, most of the cryolite used is synthetic rather than the naturally occurring mineral. 

What explanation can you give of the fact that calcium fluoride, CaFj, (the mineral fluorite), is a crystalline substance with high melting point, whereas stannic chloride, SnCl, is an easily volatile liquid ... 

Most parts of the oceans are nearly saturated with CaF2. The mineral fluorite, CaF2, may precipitate when ocean water evaporates. A saturated solution of CaF2 at 25°C has a solubility of 3.4 x 10 " M. Calculate the solubility product constant for CaF2. 

Ruorine comes from the Latin wordfluere, which means to flow. The mineral fluorite, which contains fluorine and calcium, is used to lower the melting points of other minerals to make it easier to separate them from their ores. Fluorine compounds are added to toothpaste and drinking water to protect tooth enamel from decay. A compound of fluorine and carbon provides a non-stick coating for the cookware shown in Figure 7-20a. When fluorine reacts with isotopes of uranium, the gases that form are separated by differences in mass. This process is called uranium enrichment it provides the uranium-235 fuel for nuclear reactors. 

Major faults of the Illinois Basin area are shown in Fig. 10. The southern portion of the basin is intensely faulted northeast-trending faults in southeast Illinois and northwest Kentucky are associated with the lllinois-Kentucky Huorspar district. A number of these faults in Mississippian limestone beds are mineralized with the ore minerals fluorite (CaF2), sphalerite, and galena, and with gangue minerals such as calcite and pyrite... 

Barium sulfate, BaS04, occurs in the mineral barite (a). Calcium fluoride, Cap2, occurs in the mineral fluorite (b). Both are clear, colorless crystals. Minerals are often discolored by impurities. 

The element fluorine can be obtained by the electrolysis of combinations of hydrofluoric acid and potassium fluoride. These compounds can be made from the calcium fluoride, Cap2, found in nature as the mineral fluorite. Fluorite s commercial name is fluorspar. Crude ores containing fluorite have 15% to 90% Cap2. What minimum mass, in metric tons, of crude ore is necessary to make... 

The general formula of crystals with the fluorite structure is MAS. The mineral fluorite, calcium fluoride, CaF2, which names the group, is sometimes also called fluorspar. 

Many other inorganic compounds can be derived from metal packing in similar ways. For example, the structure of the mineral fluorite, CaF2, can be envisaged as the A1 structure of the metal Ca, with every tetrahedral site filled by fluorine. Each Ca atom is surrounded by a distorted cube of fluorine atoms. 

Turns are pure CaC03. Calcium fluoride (CaF2) is the principal source of fluorine in the production of hydrofluoric acid (HF). Hydrofluoric acid is often the source of fluorine in the processes of manufacturing fluorine-containing chemicals. The mineral fluorite (CaF2) occurs in nature in several colors and is used as a gemstone. 

The halogens form a very large number of compounds. In the elemental state they form diatomic molecules, X2. In nature, however, because of their high reactivity, halogens are always found combined with other elements. Chlorine, bromine, and iodine occur as halides in seawater, and fluorine occurs in the minerals fluorite (CaF2) (see Figure 20.18) and cryolite (Na3AlF6). 

Calcium fluoride occurs naturally as the mineral fluorite (fluorspar). Figure 5.18a shows a unit cell of Cap2. Each... 

Most common is the theory of chemisorption of collectors at the surface of solid particles. However, it is, as a rule, at the same time noted that simultaneously concurrent processes take place, which are connected both with adsorption of surfactants at 1/g interfaces and with their interaction with ions in the flotation pulp. Thus, it is shown in [66] that saturated C 2—Cj4 fatty acids are selectively chemisorbed on calcium carbonate surfaces which provides them with an effective hydrophobisation. At the same time, C5—Cg acids are adsorbed mainly at 1/g interfaces which produces a substantial influence on the stability of the flotation foams. Free and Miller [67] have thoroughly investigated the behaviour of sodium oleate in the flotation of a calcium mineral, fluorite. It has been established that calcium dioleates are formed both in the bulk and at 1/s interfaces. In this case, an effective hydrophobisation of the surface of fluorite particles takes place both due to the interaction of oleate with calcium ions on the active sites and by adsorption of calcium dioleates formed in the solution. It has been once more confirmed [68] that classical collecting agents, xanthogenates, e.g. ethyl xanthogenate, form on the... 

The common mineral fluorite (Figure 4) forms beautiful cubic crystals. This mineral is mainly calcium fluoride. What ions are present in this mineral ... 

Simple oxides with large cations - such as Zr, Th, and U " - crystallize with the fluorite structure (the mineral fluorite itself is CaF2). Both, Zr02 and UO2 have been well studied and will be emphasized in this chapter, though neither story is simple. 

The mineral fluorite (Cap2), also called fluorspar, is converted to hydrofluoric acid (HF) for the synthesis of refrigerants and fluoropolymers. A large fraction of the world s supply of fluorspar is controlled by China. 

CaF2 occurs naturally as the mineral fluorite and in the cubic system with the Fm3m group. In this structure, the calcium ions are surrounded by eight neighboring fluoride ions, whereas the fluoride ions are surrounded by a tetrahedron of four calcium ions [2] as shown in Fig. 16.1. Although perfectly packed crystalline samples are colorless, the mineral is often deeply colored due to the presence of F-centers [2]. 

Fluorine had been suspected as an element present in the mineral fluorite (CaF2) and had been officially named in 1812 by A. M. Ampere and H. Davy (Latin fluere, to flow, from the use of fluorite as a flux). Its isolation, however, remained one of the chief unsolved problems of inorganic chemistry for more than 70 years because of the great reactivity of this element. In 1886, the French chemist H. Moissan successfully prepared elemental fluorine by the electrolysis of a cooled solution of dry potassium hydrogen fluoride (KHF2) in anhydrous hydrofluoric... 

The mineral fluorite is calcium fluoride, Cap2. Calculate the solubility (in grams per liter) of calcium fluoride in water from the solubility product constant... 

The objective lens is the most important part of the optical system. All lenses have information engraved on them, and it is helpful to be able to interpret this. An old lens may only show its focal length, but a typical modern lens may have Pol 25/0.55 0.17/170. The letters indicate the type of lens, here strain-free, suitable for use with polarized light. Different manufacturers may use different abbreviations, but most are readily understood. The most obscure is FI or Fluor this indicates a high quality general purpose lens, once (but no longer) made using the mineral fluorite. 

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