Fluorine hydrofluoric acid

Lead will resist chlorine up to about 100°C , is used for dry bromine at lower temperatures and is fairly resistant to fluorine . Hydrofluoric acid does not passivate lead, so lead should not be used in this environment. Lead is very resistant to sulphur dioxide and fairly resistant to sulphur trioxide, wet or dry, over a wide temperature range . ... 

Fluorine Hydrofluoric acid (HF) is a by-product of aluminum production by electrolysis cind the synthesis of chlorofluorocarbons (CFCs). Although in water HF is a weak acid, it s extremely toxic. HF poisoning causes deep ulceration or scarring of body tissue with a delayed effect, slowly replacing calcium in bodily tissue (flesh and bones). There s no pain at first because it s a weak acid, but when the calcium in the bones starts to be replaced by the more electronegative fluorine it feels similar to growing pains, and may be too late. Merely five-minute iexposure to 10,000 ppm concentration in the air is fatal to humans. 

Fluorine and its compounds are used in producing uranium (from the hexafluoride) and more than 100 commercial fluorochemicals, including many well known high-temperature plastics. Hydrofluoric acid etches the glass of light bulbs, etc. Fluorochlorohydrocarbons are extensively used in air conditioning and refrigeration. 

FLUORINECOMPOUNDS,ORGANIC - FLUORINATED ALIPHATIC COMPOUNDS] (Vol 11) -for hydrofluoric acid burns [FLUORINE COMPOUNDS, INORGANIC - ALDTONIUT (Volll)... 

Water. Fluorine reacts with water to form hydrofluoric acid [7664-39-3] HF, and oxygen difluoride [7783 1-7] OF2. In dilute (<5%) caustic solutions, the reaction proceeds as follows ... 

Raw Material. The principal raw material for fluorine production is high purity anhydrous hydrofluoric acid. Each kilogram of fluorine generated requires ca 1.1 kg HE. Only a small portion of the hydrofluoric acid produced ia the United States is consumed ia fluorine production. The commercial grade is acceptable for use as received, provided water content is less than 0.02%. Typical specifications for hydrofluoric acid are... 

Price. The 1993 U.S. price for fluorine in cylinders was 109/kg for 2.2 kg and 260/kg for 0.7 kg cylinders. The price in large volumes is determined by (/) the price of hydrofluoric acid (2) power costs, ca 4.5 kWh electricity is required for each kilogram of fluorine produced (J) labor costs (4) costs to maintain and rebuild cells and (5) amortization of fixed capital. Fluorine production is highly capital intense. In addition, purification, compression, packaging, and distribution in cylinders increase the cost significantly. 

Fluorine, the most reactive element known, is a dangerous material but may be handled safely using proper precautions. In any situation where an operator may come into contact with low pressure fluorine, safety glasses, a neoprene coat, boots, and clean neoprene gloves should be worn to afford overall body protection. This protection is effective against both fluorine and the hydrofluoric acid which may form from reaction of moisture in the air. 

Burns. Skin bums resulting from contact with pure fluorine gas are comparable to thermal bums and differ considerably from those produced by hydrogen fluoride (114). Fluorine bums heal much more rapidly than hydrofluoric acid bums. 

Eluorspar assay may be completed by fluoride determination alone, because the mineralogical grouping rarely iacludes fluorine minerals other than fluorite. Calcium can be determined as oxalate or by ion-selective electrodes (67). SiUca can be determined ia the residue from solution ia perchloric acid—boric acid mixture by measuriag the loss ia weight on Aiming off with hydrofluoric acid. Another method for determining siUca ia fluorspar is the ASTM Standard Test Method E463-72. 

To convert naturally occurring uranium oxide, yellow cake or U Og, to the gaseous UF, hydrofluoric acid is first used to convert the U Og to UF. Further fluorination using fluorine (generated from more HF) is employed to convert the UF to UF. The UF is then processed at gaseous diffusion enrichment plants. 

Niobium Penta.fIuoride, Niobium pentafluoride is prepared best by direct fluorination of the metal with either fluorine or anhydrous hydrofluoric acid at 250—300°C. The volatile NbF is condensed in a pyrex or quartz cold trap, from which it can be vacuum-sublimed at 120°C to yield colorless monoclinic crystals. It is very hygroscopic and reacts vigorously with water to give a clear solution of hydrofluoric acid and H2NbOF ... 

The perchloryl fluoride [7616-94-6] FCIO, the acyl fluoride of perchloric acid, is a stable compound. Normally a gas having a melting poiat of —147.7° C and a boiling poiat of —46.7°C, it can be prepared by electrolysis of a saturated solution of sodium perchlorate ia anhydrous hydrofluoric acid. Some of its uses are as an effective fluorinating agent, as an oxidant ia rocket fuels, and as a gaseous dielectric for transformers (69). 

Qua.driva.Ient, Zirconium tetrafluoride is prepared by fluorination of zirconium metal, but this is hampered by the low volatility of the tetrafluoride which coats the surface of the metal. An effective method is the halogen exchange between flowing hydrogen fluoride gas and zirconium tetrachloride at 300°C. Large volumes are produced by the addition of concentrated hydrofluoric acid to a concentrated nitric acid solution of zirconium zirconium tetrafluoride monohydrate [14956-11-3] precipitates (69). The recovered crystals ate dried and treated with hydrogen fluoride gas at 450°C in a fluid-bed reactor. The thermal dissociation of fluorozirconates also yields zirconium tetrafluoride. 

As a leader in fluorine technology, Honeywell Chemicals is committed to safety, customer satisfaction, the development of new technology, and the manufacture and supply of fluorochemicals worldwide. We are proud to be the world s largest producer of hydrofluoric acid and sulfur hexafluoride supplying customers globally. 

In the past 20 years, the application of fluorinated reagents in chemistry experienced tremendous growth Some well known denvatives of hydrofluoric acid and tri-fluoroacetic acid found new applications, and many new classes of synthetically useful fluorinated organic and inorganic compounds have been synthesized... 

Almost all of the biomedical research done in the 25 years following the liquid-breathing work was conducted with commercially available fluorocarbons manufactured for various industnal uses by the electrochemical Simons process (fluonnation in a hydrofluoric acid solution) or the cobalt fluoride process (fluori-nation with this solid in a furnace at about 200 C) These processes tended to yield many by-products, partly because they were, to some extent, free radical reactions and partly because it was difficult to easily achieve complete fluonnation Aromatic hydrocarbons gave better products with the cobalt tnfluonde [73] method, whereas saturated hydrocarbons yielded better products with fluonnation using diluted or cooled gaseous fluorine (Lagow) Incompletely fluormated matenal was either... 

Fluor-verbindung, /. fluorine compound, -wasserstoff, m. hydrogen fluoride hydrofluoric acid. 

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Tantalum is severely attacked at ambient temperatures and up to about 100°C in aqueous atmospheric environments in the presence of fluorine and hydrofluoric acids. Flourine, hydrofluoric acid and fluoride salt solutions represent typical aggressive environments in which tantalum corrodes at ambient temperatures. Under exposure to these environments the protective TajOj oxide film is attacked and the metal is transformed from a passive to an active state. The corrosion mechanism of tantalum in these environments is mainly based on dissolution reactions to give fluoro complexes. The composition depends markedly on the conditions. The existence of oxidizing agents such as sulphur trioxide or peroxides in aqueous fluoride environments enhance the corrosion rate of tantalum owing to rapid formation of oxofluoro complexes. 

Nevertheless, Ta5+ and Nb5+ interact with aqueous media containing fluorine ions, such as solutions of hydrofluoric acid. On the other hand, as was clearly shown by Majima et al. [448 - 450], the increased hydrogen ion activity can also significantly enhance the dissolution rate of oxides. The activity of hydrogen ions can be increased by the addition of mineral salts or mineral acids to the solution. 

The addition of strong acids or neutral salts, such as NH4F, to the hydrofluoric acid solution was recommended in order to increase the concentrations and activities of fluorine and hydrogen ions [451]. 

Hydrofluoric acid, at relatively high concentrations and at elevated temperatures, dissolves columbite-tantalite concentrates at a reasonable rate. The dissolution process is based on the fluorination of tantalum, niobium and other metal oxides and their conversion into soluble complex fluoride acids yielding complex fluoride ions. 

First, handling of highly concentrated acids, including hydrofluoric acid, especially at elevated temperatures, is very dangerous and requires use of special equipment and appropriate training of personnel. Second, the required amount of fluorine (or HF) is well above the amount needed based on the interaction stoichiometry. This results in large amounts of liquid waste, the treatment of which is very expensive. 

The main advantages of the method can be formulated as follows. First, hydrofluoric acid is not needed for the decomposition stage the amount of fluorine required for the raw material decomposition can be calculated and adjusted as closely as possible to the stoichiometry of the interaction. Since the leaching of the fluorinated material is performed with water, a significant fraction of the impurities are precipitated in the form of insoluble compounds that can be separated from the solution, hence the filtrated solution is essentially purified. There is no doubt that solutions prepared in this way can be of consistent concentrations of tantalum and niobium, independent of the initial raw material composition. 

The strong attraction of fluorine for protons shows up in another way. In aqueous solution, HF is a weak acid whereas HC1, HBr, and HI are strong acids. The dissociation constant of HF is 6.7 X 10-4, so hydrofluoric acid is less than 10% dissociated in a 0.1 M HF solution. 

Anhydrous AgF is best made by fluorination of finely divided silver at room temperature alternatively it can be made by dissolving silver(II) oxide in hydrofluoric acid and crystallizing ... 

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