Showing papers on "Hydrofluoric acid published in 1974"

Dissolving siliceous materials with self-acidifying liquid

Abstract: Siliceous materials in or around a well are dissolved by contacting them with a self-acidifying aqueous liquid system comprising an aqueous solution of at least one water-soluble fluoride salt mixed with a relatively slowly-reactive acid-yielding material that subsequently converts the salt solution to a hydrofluoric acid solution that has a relatively high pH but is capable of dissolving siliceous material

Rationale of the treatment of hydrofluoric acid burns

Abstract: Carney, Shirley A., Hall, M., Lawrence, J. C., and Ricketts, C. R. (1974). British Journal of Industrial Medicine, 31, 317-321. Rationale of the treatment of hydrofluoric acid burns. On contact with skin hydrofluoric acid yields hydrogen and fluoride ions, which exhaust the tissue9s buffering capacity. Fluoride was found to be toxic to skin cells, as judged by the accumulation of 3-phosphoglycerate (3-PG), at about 2 × 10 -3 mol/l fluoride ion in the medium on which skin slices were maintained. This toxicity was reversible by the dilution brought about by transfer of the skin to a fresh medium; 3-PG levels fell and tetrazolium reductase measurements showed adequate viability. Using a specific ion electrode for fluoride, the efficacy of calcium, magnesium and lanthanum salts and hyamine in lowering fluoride ion concentration in the presence of serum was examined. Lanthanum was the most effective but was itself toxic to skin cells as judged by respiration and tetrazolium reductase measurements. Calcium appeared more effective as chloride than as gluconate. Magnesium and hyamine were ineffective under the conditions of experiment. In the presence of serum, calcium gluconate is only just capable of lowering the concentration of fluoride ions to the level at which their toxic effect is negligible. The importance of rapid removal of hydrofluoric acid from the skin surface as a first-aid treatment is emphasized.

Process for the manufacture of aromatic 1,3-diketones

Abstract: Aromatic 1,3-diketones are produced by reacting aromatic compounds with acetoacetyl fluoride optionally substituted in γ-position by fluorine, chlorine and/or bromine, in hydrofluoric acid of at least 90% strength at a temperature of from about -40 to +50°C. The products obtained are important starting products and intermediates for the manufacture of dyestuffs, plastics and pharmaceuticals. Furthermore they can be used for the formation of metal complexes and metal extracting agents, solution intermediaries and solvents.

Bonding of Titanium Alloys

Abstract: Surface pretreatments affect joint strength, some improve it, e.g. etching in aqueous hydrofluoric acid or oxidation in alkaline hydrogen peroxide; while others decrease the strength e.g. etching in acids containing high concentrations of oxidising agents. For Ti-6A1-4V alloy, best results are obtained by either etching in aqueous hydrofluoric acid or oxidation in alkaline hydrogen peroxide for about two hours. The results indicate that a pretreatment which leaves a coherent TiO2-rutile layer, on a rough surface, form the strongest joints. Surface roughness is shown to enhance bond strength.

Aqueous hydrogen fluoride system

Abstract: The thermodynamic properties of equilibria H/sup +/ + F/sup -/ = HF and HF + F/sup -/ = HF/sub 2//sup -/ were evaluated at 15/sup 0/, 25/sup 0/, and 35/sup 0/C in water NaNO/sub 3/ was used to maintain a constant ionic strength of 05000 m No evidence was found to indicate the presence of complexes higher than HF/sub 2//sup -/ or of polynuclear complexes (14 refs)

Method of processing of waste gases

Abstract: A method of processing of waste gases containing hydrogen fluoride and silicon tetrafluoride or hydrogen fluoride, silicon tetrafluoride and sulfur dioxide by absorption of hydrogen fluoride and silicon tetrafluoride or hydrogen fluoride, silicon tetrafluoride and sulfur dioxide from waste gases by water solutions containing ammonium compounds such as ammonium carbonate, ammonium bicarbonate and ammonium fluoride. In addition to these ammonium compounds the absorption solutions contain sodium fluoride and ammonia. The absorption process produces a water solution containing ammonium fluoride and the precipitate of sodium fluosilicate. This solution is treated with sodium carbonate after which the precipitate of sodium fluoride is separated from the solution and the latter is delivered for absorption.

Preparation of perfluorinated organic sulfonyl fluorides

Abstract: In the electrochemical fluorination of an alkanesulfonyl halide wherein an electric current is passed through a cell containing said alkanesulfonyl halide dissolved in hydrofluoric acid to produce a perfluorinated alkanesulfonyl fluoride, the improvement which comprises including in said cell an unsaturated cyclic sulfone.

Corrosive paste for cleaning metals, esp stainless steel - contg xanthane polysaccharide as thickening agent

Abstract: Corrosive paste for cleaning metal surfaces, esp. stainless steel, contains hydrofluoric acid and as thickening agent, a polysaccharide of the xanthane type. The paste pref. contains 0.5-6.0, esp. 1.5-3.0 wt% thickener, a pref. compsn. consisting of, by wt., 5-30, esp. 10-20% nitric acid, 0-10, esp. 0.5-3% hydrofluoric acid, and 1.5-3% thickener. The paste may also contain sulphuric- and/or hydrochloric acids, possibly as replacements for the nitric acid; in addn., surfactants which are resistant to acids may be used, esp. surfactants contg. fluorine. The paste is used for pickling special steels, esp. welded joints or oxidised surfaces on stainless steels; the paste can also be used with success on other ferrous, and non-ferrous metals. The polysaccharide used does not break down in the acid soln., which occurs when other thickeners, e.g. methyl cellulose, are used.

Recovery of aluminum fluoride

Abstract: An aqueous solution containing fluorides, for example, hydrofluoric acid, is reacted with commercial grade aluminum oxide comprising predominantly alpha alumina at an elevated temperature to produce a complex aluminum hydroxide fluoride hydrate that precipitates from the solution. The commercial grade aluminum oxide contains an amount of gamma and delta alumina such that the aluminum oxide has a loss of weight on ignition of from about 0.5% to about 2.5%. The resulting aluminum hydroxide fluoride hydrate precipitate is recovered and calcined in a non-oxidizing atmosphere to produce aluminum fluoride suitable for use in the electrolytic production of aluminum.

Process for preparation of hot-pressable magnesium fluoride

Abstract: A process is disclosed for converting basic magnesium carbonate into pure hot-pressable magnesium fluoride such as is used for the hot-pressing of infra-red radiation transmitting optical bodies. The process includes contacting a slurry of basic magnesium carbonate with carbon dioxide to form enough magnesium bicarbonate or hydrates of magnesium carbonate, in situ, to alter the particles in the slurry. Carbonation of the slurry increases solubility of the solids by establishing an equilibrium relationship in solution between the unstable magnesium bicarbonate and hydrates of magnesium carbonate particles. When the carbonated slurry is contacted with a slight excess of hydrofluoric acid it precipitates solid particles of fine hydrous magnesium fluoride. Neutralization of excess hydrofluoric acid is effected with ammonium hydroxide. The solid particulate precipitate is dried and calcined to yield hot-pressable magnesium fluoride powder of exceptional purity and consistent quality. A hot-pressable magnesium fluoride powder has been prepared which has a specific and uniform refractive index, nD 1.3850 at 20* C; the powder is made up of primary particles the majority of which have an average particle diameter of greater than 5 Mu (microns), permitting the hot-pressing of the powder without grinding it.

A method for the direct titrimetric determination of iron(III) in silicate rocks

Abstract: The rock sample is decomposed with hydrofluoric acid in the manner of a conventional iron(II) determination, and the iron(III) in the resulting solution is determined by titration with a solution of ferrocene (dicyclopentadienyliron) in 2-methoxyethanol. A modified procedure is necessary for rocks of very high magnesium content, and it is indicated that errors may arise in the conventional iron(II) determination when applied to rocks of this type.

{68 -Aluminum fluoride by evaporating aqueous MF solution of AlF{HD 3 {B under vacuum to dryness and heating

Abstract: Process for hydrofluorinating acetylene which comprises reacting acetylene with hydrogen fluoride in the vapor phase and in the presence of Epsilon -aluminum fluoride at a temperature from about 200* to about 380*C to produce vinyl fluoride and 1,1difluoroethane, and Epsilon -aluminum fluoride being prepared by evaporating an aqueous hydrofluoric acid solution of aluminum fluoride to dryness at a temperature from 30* to 120*C optionally followed by heating the resulting product at a temperature from 120* to 500*C.

Solvent extraction of niobium and tantalum: IX. Extraction with di-n-octylamino butanone-(2) and di-n-octylamino acetic acid

Abstract: The extraction of niobium and tantalum from hydrofluoric and oxalic acid solutions by di-n-octylamino butanone-(2) [DOAB]and by di-n-octylamino acetic acid [DOAA]has been studied, together with its dependence on the ligand and hydrofluoric acid concentrations. The species of niobium and tantalum extracted with DOAB have been isolated and characterized by analysis and i.r. spectra. I.r. spectra of the ligands as well as of the extracted species dissolved in the organic phase, were compared with the spectra of the separate substances. The complexes (DOABH)3(MeO(C2O4)3), (Me = Nb, Ta) have been isolated from oxalic acid solutions. From 0.04 M HF solutions, the species isolated correspond to the formulae (DOABH)2 · NbOF5 and (DOABH) · TaOF4 for niobium and tantalum, respectively. In higher concentrations of hydrofluoric acid the formation of the complexes (DOABH)2 · NbOF5 and (DOABH)2 · TaF7 can be deduced.

NaOH etch of fission tracks in a soda-lime-silica glass

Abstract: IT is generally known that fission tracks intersecting the surface of man-made soda–lime–silica glasses can be etched with HF at room temperature1,2. In this technique the acid attacks the tracks preferentially so that they become visible in the microscope before the glass itself is destroyed. An NaOH etch at 60° C has been reported for phosphate glasses3.

Characterization of modified alumina as adsorbent for gas-solid chromatography. Modification of alumina with potassium fluoride-hydrofluoric acid mixed solution

Abstract: The adsorption characteristics of alumina to hydrocarbons are varied by its impregnation with a mixed solution of potassium fluoride-hydrofluoric acid followed by thermal treatment. The adsorptive property of the alumina is decreased with the increase of concentration of potassium fluoride in the mixed solution and of the heating temperature. The surface layer of the modified alumina seems to consist of potassium fluoroaluminate, KxAlF3+x; with the increase of x the adsorptive property to hydrocarbons is decreased. The adsorptive property of alumina to hydrocarbons can be controlled by selecting the composition of the mixed solution and the temperature of heating after the treatment with the mixed solution. Modified alumina prepared by the present method has adsorption characteristics of Type II according to Kiselev's classification.

Corrosive Effects of Methyl Phosphonic Acid (MPA) and HF Solutions on Thin-sheet 1010 Steel, 321 Stainless Steel and 200 Nickel

Abstract: : Thin-sheet 1010 steel, 321 stainless steel, and 200 nickel, (6 to 10 mils), which have been considered as candidate diaphram materials for a binary chemical shell, were assessed for corrosion damage in a methyl-phosphonic acid solution, and in hydrofluoric acid solutions, at room temperature

Radiation‐induced emulsion copolymerization of tetrafluoroethylene with propylene. V. Formation of acid and its effect

Abstract: In the radiation-induced emulsion copolymerization of tetrafluoroethylene with propylene, it was found that hydrofluoric acid (HF) is formed in the course of polymerization. The amount of HF formed increased linearly with the irradiation time in all cases. The rate of HF formation was maximum at 0.3 wt-% emulsifier and increased linearly with tetrafluoroethylene content in the monomer mixture. On the other hand, the conversion and the molecular weight decreased remarkably by addition of 0.1M HF. The particle diameter of copolymer obtained in the presence of HF was larger than that obtained in the HF-free system. On the contrary, the number of polymer particles was less than that obtained in the HF-free system. The decrease in the conversion and the molecular weight was attributed mainly to the conversion of part of ammonium perfluorooctanoate to perfluorooctanoic acid by formation of acid or addition of acid.

Dislocation etching of CaWO4 crystals

Abstract: Single crystals of calcium tungstate grown in the laboratory have been cleaved for the first time along {011} and {100} planes. These cleavages, as revealed by multiplebeam interferometric examination, prove to be fairly perfect. The etching behaviour of the various cleavages, as well as the grown faces of the crystals, is described. It has been shown that a solution of concentrated hydrofluoric acid plus chromic acid produces etch pits at the emergence sites of screw dislocations only, whereas a solution of 2N acetic acid plus chromic acid operates on both edge and screw dislocations. The results of chemical etching have been compared with those reported earlier, and the implications are discussed.

Alkylation process utilizing hydrofluoric acid with a minor amount of fluorosulfuric acid

Abstract: An improved process for alkylating at least one alkylatable isoparaffin with at least one alkylating agent selected from the class consisting of an olefin and an alkyl sulfate ester in the presence of a catalyst comprising a major amount of hydrofluoric acid and a minor amount of fluorosulfuric acid.