Bayer Aktiengesellschaft

Hans Niederprum

Karl-Heinz Mitschke

Wolfgang Bockelmann

Johann Nikolaus Meussdoerffer

Johann-Nikolaus Meussdoerffer

Hugo Vernaleken

Dieter Margotte

Werner Nouvertne

Siegfried Adelmann

Siegfried Schneider

Hans-Georg Nieder-Vahrenholz

Heinz Gunter Klein

Helmut Vorbruggen

Hans-Heinrich Moretto

Manfred Kapps

Armand De Montigny

Klaus Geisler

Ulrich Finke

Manfred Wechsberg

Heinz Jonas

Wolfgang Weis

Volker Beyl

Hans-George Nieder-Vahrenholz

Wolfgang Bockelman

Georg Uecker

Peter Voss

In the disintegration of a chromite or chromium-containing residue, wherein the chromium-containing material is disintegrated with an alkaline compound in the presence of oxygen and a diluent at a temperature above about 800.degree. C. and thereafter leached, the improvement which comprises pre-roasting the chromium-containing material prior to addition of the alkaline compound. Pre-roasting can be effected at 400.degree. to 1200.degree. C. with addition of certain amounts of silica dioxide and/or aluminum oxide and such additives, depending on the chromium containing material, if still required, are added--prior to disintegration and leaching--in such a quantity to establish a ratio of SiO.sub.2 : AL.sub.2 O.sub.3 of about 2:1 and further a ratio, calculated on the basis of NaOH as the alkaline compound, of SiO.sub.2 : Na.sub.2 O of about 1:0.5 plus a Cr.sub.2 O.sub.3 : Na.sub.2 O ratio of about 1:2 to 1:4. Residues from previous leaching cycles can be present during disintegration as solid diluents but their contents of SiO.sub.2 and/or Al.sub.2 O.sub.3 are not taken into account in calculating the SiO.sub.2 :AL.sub.2 O.sub.3 ratios. The process gives excellent results even with starting materials relatively high in SiO.sub.2 which are difficult to disintegrate to materials of desirable properties by other methods.

Disintegration of chromites

Employing as surface active agents salts of perfluoroalkane sulphonamides, preferably of the formula ##STR1## in which R.sub.F is a perfluorinated aliphatic group having 4 to 20 C-atoms,

Use of perfluoroalkane sulphonamide salts as surface active agents

1,1-Difluoro-2-chloroethylene is used as the propellant in an aerosol spray can. It is reasonably stable and non-flammable but will in time degrade in the atmosphere.

1,1-Difluoro-2-chloroethylene as aerosol propellant

A process for the preparation of a hydroxyalkylperfluoroalkane sulphonamide of the formula ##STR1## wherein R.sub.F is a perfluoroalkyl group having from 1 to 20 carbon atoms;

Process for the preparation of hydroxyalkylperfluoroalkane sulphonamides

In the production of linear and branched equilibrated acyloxy-containing organopolysiloxanes by reacting a chlorosilane of the formula

Process for the production of siliconfunctional polyorganosiloxanes

A process for the preparation of a perfluoroalkanesulphonic acid ester of the formula

Silyl esters of perfluoroalkanesulphonic acid esters and a process for

In the production of a foamed synthetic material by the reaction of starting materials which undergo a polymerization, polycondensation or polyaddition reaction to produce a high molecular weight synthetic material in the presence of a blowing agent, e.g. a polyurethane, or by foaming an unfoamed thermoplastic synthetic material by means of a blowing agent, the improvement which comprises employing 1,1,1-trifluoro-2-chloroethane as the blowing agent, optionally in admixture with 1,1-difluoro-2-chloroethane.

1,1,1-Trifluoro-2-chloroethane as blowing agent for polyurethane foam

A process for the preparation of a chrome-tanning agent and Glauber's salt from sodium bisulphate contaminated with chromium compounds obtained as by-product from the manufacture of chromic acid from solid sodium dichromate and sulphuric acid, comprising

Process for the preparation of a chrome tanning agent and Glauber's salt

Production of tetraethyl ammonium perfluoroalkyl sulphonates (C.sub.2 H.sub.5).sub.4 N.sym.R.sub.F SO.sub.3 .crclbar., wherein R.sub.F represents a perfluorinated alkyl radical with about 4 to 10 carbon atoms, by reacting crude perfluoroalkyl sulphonic acid fluoride, i.e. perfluoroalkyl sulphonic acid fluoride which has not been especially purified, with triethylamine and an ethoxy silane, preferably dimethyl diethoxy silane, methyl triethoxy silane or tetraethoxy silane in an inert solvent at temperatures of about 10.degree. to 60.degree. C., preferably about 20.degree. to 40.degree. C. The process according to the invention is particularly suitable for the production of tetraethyl ammonium perfluorooctane sulphonate.

Production of tetraethyl ammonium perfluoroalkyl sulphonate

In the production of a synthetic fluorspar of low silicon dioxide content wherein hexafluosilicic acid is added in an amount ranging from slightly below up to about stoichiometric amount to an aqueous calcium carbonate suspension at a temperature from about 0.degree. to 40.degree. C., and the calcium fluoride formed is separated off from the dilute silica sol and optionally washed out, the improvement which comprises reacting the calcium carbonate with the hexafluosilicic acid in such a way that the pH-value of the fully reacted solution amounts to between about 3.6 and 4.6, and adding a fast-reacting proton acceptor to the reaction mixture immediately before separation of the calcium fluoride in amount sufficient to raise the pH to about 5.0 to 6.4, preferably about 5.8 to 6.2. Suitable proton acceptors include the alkali metal and ammonium hydroxides carbonates and hydrogen carbonates or alkaline earth metal hydroxide. Anionic or non-ionic dispersants may also be added and the calcium fluoride is separated by decanting or centrifugation within about 1 second to 10 minutes, preferably about 4 to 10 seconds, after raising the pH. The separated calcium fluoride may be washed to remove silica sol therefrom and then again be treated to raise its pH before separation.

Production of synthetic fluorspar

In the recovery of chromium from a residue containing chromate and vanadate, by oxidative decomposition of a chromium and vanadium-containing ore in the presence of an alkali at temperatures of about 600 to 1200.degree. C., and leaching such residue with water, the improvement which comprises adding titanium dioxide to the residue and heating, whereby upon leaching the chromium enters the water while the vanadium is substantially left in the residue.

Producing chromate substantially free of vanadium

In the disintegration of at least one chromium source selected from the group consisting of a SiO.sub.2 -containing chromite and a chromium-containing residue with an alkali compound at a temperature above about 800.degree. C in the presence of atmospheric oxygen and a lime-free diluent, followed by leaching of the mixture with at least one of water and/or a chromium (VI)-containing aqueous solution, the improvement which comprises including in the mixture to be disintegrated an aluminum compound and at least sufficient alkali to form alkali chromate and to convert the SiO.sub.2 into an alkali-aluminum silicate corresponding to the formula nMe.sub.2 O . mSiO.sub.2 . Al.sub.2 O.sub.3, wherein Me is at least one of sodium and potassium, 0.8 .ltoreq. n .ltoreq. 1.2 and 1.3 .ltoreq. m .ltoreq. 4.3.

Disintegration of silica-rich chromite

In the chrome-tanning of skins with a chromium (III) salt and an acid-binding agent, the improvement which comprises effecting the chrome-tanning in the presence of a water-soluble partial ester of a polycarboxylic acid containing 4 to 11 carbon atoms which ester hydrolyzes into the free acid or its salt. The partial ester is advantageously present in about 0.5 to 2, preferably 1,3 to 1.8, times the molar amount of the chromium salt expressed as Cr.sub.2 O.sub.3. The tanning composition can be formed by dissolving the desired ingredients and the solution spray dried to provide a properly formulated powder which can thereafter by employed to re-formulate the solution.

Tanning skins using polycarboxylic acid partial esters

In the alkaline-oxidative disintegration of chromites into chromates with an alkali comprising reacting a chromium ore in the presence of oxygen and a diluent, and leaching the reaction mixture with at least one of water and/or a chromate-containing aqueous solution, the improvement which comprises reacting the residue obtained after leaching with an excess of alkali, based on the chromium oxide content of the residue, in the presence of oxygen, grinding the reaction mixture and, without leaching, employing the ground reaction mixture as an alkali source in another chromite disintegration cycle. The alkali reacted with the leaching residue is preferably sodium and/or potassium hydroxide and/or carbonate and is employed in about 100 to 400%, and preferably about 150 to 330%, of the stoichiometric amount based on the chromium oxide content of the leaching residue.

Alkaline disintegration of chromites

In the etching of glass wherein glass is contacted with an aqueous etching bath containing hydrofluoric acid, and the glass is thereafter removed from the bath and rinsed, the improvement which comprises dissolving in the etching bath an acid-resistant wetting agent. Preferably the wetting agent contains fluorine, e.g. a perfluoralkane sulfonic acid quaternary ammonium salt, a perfluoralkane carboxylic acid salt, an alkoxylation product of a perfluoralkane sulfonamide, or the like.

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Monheim, Germany

Hans Niederprum