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Sulfuric acid with fluorspar

A basic step in hydrofluoric acid manufacture is the reaction of sulfuric acid with fluorspar (calcium fluoride) to produce hydrogen fluoride and calcium sulfate. Spent alumina is also generated by the defluorination of some hydrofluoric acid alkylation products over alumina. It is disposed of or sent to the alumina supplier for recovery. Other solid residuals from hydrofluoric acid alkylation include any porous materials that may have come in contact with the hydrofluoric acid. [Pg.104]

Industrially hydrogen fluoride is manufactured by the reaction of sulfuric acid with fluorspar (acid grade) ... [Pg.132]

Hydrofluoric acid is the most basic common precursor of most fluorochemicals. Aqueous hydrofluoric acid is prepared by reaction of sulfuric acid with fluorspar (CaF2). Because HF etches glass with formation of silicon tetrafluoride, it must be handled in platinum, lead, copper. Monel (a Cu-Ni alloy developed during the Manhattan Project), or plastic (e.g. polyethylene or PTFE) apparatus. The azeotrope contains 38 % w/w HF and it is a relatively weak acid (pfC 3.18, 8 % dissociation), comparable with formic acid. Other physicochemical properties of hydrofluoric acid are listed in Table 1.2. [Pg.4]

Anhydrous hydrogen fluoride is usually produced commercially by reacting hot, concentrated sulfuric acid with fluorspar ... [Pg.127]

Fluoroboric (or Fluoboric) Acid, HBF , mw 87.83 colorless clear, strongly acid liq bp 130° (dec) miscible with w ale. Can be prepd by action of boric + sulfuric acid on fluorspar. Used for prepn of fluoboraces and stabilized diazo sales. Its specially purified so In used in patented process for electrolytic brightening of Al... [Pg.519]

Hydrogen fluoride is manufactured by the reaction with sulfuric acid of fluorspar, a fluorine-containing mineral. [Pg.272]

Production of hydrogen fluoride from reaction of Cap2 with sulfuric acid is the largest user of fluorspar and accounts for approximately 60—65% of total U.S. consumption. The principal uses of hydrogen fluoride are ia the manufacture of aluminum fluoride and synthetic cryoHte for the Hall aluminum process and fluoropolymers and chlorofluorocarbons that are used as refrigerants, solvents, aerosols (qv), and ia plastics. Because of the concern that chlorofluorocarbons cause upper atmosphere ozone depletion, these compounds are being replaced by hydrochlorofluorocarbons and hydrofluorocarbons. [Pg.137]

Gaseous hydcofluoiic acid is generally made by the reaction of acid-grade fluorspar [14542-23-5] Cap2, with sulfuric acid (see Fluorine compounds, inorganic)... [Pg.96]

Hydrofluoric Fluorspar-sulfuric acid Sip4, HF Scrubber (some with caustic)... [Pg.498]

Most CFCs are manufactured by combining hydrogen fluoride and either carbon tetrachloride or chloroform. The hydrogen fluoride comes from fluorspar, CaF2, reacting with sulfuric acid. The chlorinated methanes are manufactured from methane. Important reactions in the manufacture of CFC-11 and -12 and HCFC-22 are given in Fig. 12.2. [Pg.212]

In 1768 A. S. Marggraf made the first chemical investigation of fluorite, distinguished it from heavy spar and selenitic spar (sulfates of barium and calcium), and showed that it is not a sulfate (77, 78). When he distilled pulverized fluorspar with sulfuric acid from a glass retort, the glass was badly attacked and even perforated. He noticed that an earth [silica] appeared in the receiver, and therefore concluded that the sulfuric acid had liberated a volatile earth from the fluorspar (77). [Pg.756]

In 1771 G. W. Scheele investigated a green variety of fluorspar from Garpenberg and a white one from Gislof in Scania. He found that the green specimen contained a trace of iron but that the white one did not. When he heated the pulverized mineral with oil of vitriol [sulfuric acid], he noticed that the inner surface of the glass retort became corroded,... [Pg.756]

Fluorspar is also used to manufacture hydrogen fluoride (hydrofluoric acid, aqueous and anhydrous) is manufactured in heated kilns by the reaction of fluorspar with sulfuric acid. [Pg.240]

Hydrofluoric acid (melting point -83.1°C, boiling point 19.5°C) is produced by treating fluorspar (CaF2) with 20% oleum and heating it with sulfuric acid in a horizontal rotating drum. [Pg.265]

Hydrogen fluoride is produced worldwide in 10 ta by reaction of fluorspar with sulfuric acid (equation 1). The reaction is endothermic (AF/298 = 59kJmol ) and is carried out in rotary furnaces that produce up to 45td . The crude HF is scrubbed by H2SO4 and purified further by distillation as required. Silicon tetrafiuoride is a by-product from silicate impurities (equation 2) and is recovered as H2SiFe (equations). Another by-product, CaS04, is used in cement production and other applications. ... [Pg.1339]

The hexafluorosilicic acid solutions produced as a byproduct in the production of phosphoric acid by the digestion of apatite [Ca (P04)2 Cap2 with 2-4% fluorine content, byproduct silicon dioxide] with sulfuric acid are important raw materials for the manufacture of fluorochemicals (e.g. manufacture of sodium fluoride NaF). The reserves of available fluorine from fluorapatite are estimated to be 327 10 t Cap2 (of which 32 10 t is in the USA), the fluorine quantities available in fluorapatite being therefore considerably greater than the fluorspar reserves. However, the industrial exploitation is still negligible. The reasons therefor are that ... [Pg.130]

The small quantities of compounds such as carbonates or oxides (e.g. iron oxide) in the fluorspar also react with the sulfuric acid, necessitating a ca. 5-10% excess of sulfuric acid. Silicon dioxide reacts with the already formed... [Pg.132]

The reaction of solid fluorspar with liquid sulfuric acid produces a solid (calcium sulfate) and a gaseous (hydrogen fluoride) product. The reaction passes through a paste-like phase. Many reactor modifications have been developed to attain an optimal reaction in this phase. The aim is thorough mixing of this phase, which is achieved by internal fittings in the rotary tube (e.g. paddles) or by kneading the reaction mixture in a kneader. [Pg.133]

Upon leaving the furnace the hydrogen fluoride formed is scrubbed with concentrated sulfuric acid, which is subsequently utilized in the reaction with fluorspar. In this scrubbing the water in the hydrogen fluoride is removed by being bound by added oleum. [Pg.133]

Buss has developed a widely operated variant of the fluorspar decomposition in which the pre-reaction is carried out in a continuously operating kneader, which is linked to an indirectly heated rotary tube furnace in which the reaction proceeds to completion. In a further variant (a process developed by DuPont) the necessary heat is supplied by reacting sulfur trioxide with water to sulfuric acid in the reactor (e.g. in a fluidized bed process). The heat of sulfuric acid formation thereby liberated provides much of the energy for the endothermic fluorspar decomposition. [Pg.135]

In the PCUK process calcined hydrated aluminum oxide is reacted with a mixture of hydrogen fluoride and furnace gas. The hydrogen fluoride is produced in situ from fluorspar and sulfuric acid in a directly heated rotary tube furnace. The resulting mixture of hydrogen fluoride and furnace gases is reacted with calcined aluminum hydroxide to aluminum fluoride in a fluidized bed reactor. [Pg.138]

The manufacture of boron trifluoride proceeds either discontinuously by reacting borates with fluorspar and oleum or continuously by reacting, for example, hydrogen fluoride with boric acid in the presence of sulfuric acid, to bind the water formed ... [Pg.142]

Calcium. sulfate is formed as a byproduct in the industrial manufacture of hydrofluoric acid by reacting fluorspar (Cap2) with concentrated sulfuric acid in rotary kilns at ca. 200°C (see Section 1.7.1) ... [Pg.420]

The first unsuccessful attempts to convert alcohols directly into alkylfluorides were documented in 1782, when Scheele treated ethanol with hydrofluoric acid vapor obtained from the reaction of fluorspar (CaF2) with sulfuric acid [115]. Despite this and other early failures, a variety of successful and convenient strategies designed to solve this general synthetic problem have been developed, especially since the 1920s. [Pg.57]


See other pages where Sulfuric acid with fluorspar is mentioned: [Pg.206]    [Pg.206]    [Pg.519]    [Pg.519]    [Pg.55]    [Pg.273]    [Pg.274]    [Pg.932]    [Pg.546]    [Pg.367]    [Pg.762]    [Pg.375]    [Pg.663]    [Pg.273]    [Pg.274]    [Pg.439]    [Pg.1339]    [Pg.273]    [Pg.274]    [Pg.129]    [Pg.134]    [Pg.420]    [Pg.438]    [Pg.1338]    [Pg.493]   
See also in sourсe #XX -- [ Pg.1063 ]




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