Hoechst Aktiengesellschaft

Hoechst Aktiengesellchaft

Gero Heymer

Gunther R Schimmel

Reinhard Gradl

Hans-Werner Stephan

Klaus Hestermann

Alexander Maurer

Klaus Lehr

Wolfgang Scheibitz

Christian May

Renate Adrian

Georg Elsner

Klaus Jodden

Klaus Schrodter

Klaus-Peter Ehlers

Bernd Lippsmeier

Horst-Dieter Wasel-Nielen

Jurgen Stenzel

Friedrich-Wilhelm Dorn

Manfred Wolter

Werner Krause

Hartfrid Vollmer

Ursus Thummler

Theodor Auel

Herbert Panter

Hasso Spott

Klaus P Ehlers

Horst Staendeke

Werner Pieper

Peter Wirtz

Werner Klose

Werner Kowalski

Hannsjorg Ulrich

Friedrich Kolkmann

Dieter Peters

Raban Von Schenck

Herbert Ressel

Bernhard Hofmann

Markus Erpenbach

Gerhard Bettermann

Hermann Schrodter

Hermann Klein

Ernst-Gunther Schlosser

G/u/ Nther Schimmel

Dieter Nolker

Gunther Shimmel

Hasso Scott

Reinhard Gradi

Jurgen Stengel

An aluminum nitride powder has a crystallite size of 40 to 150 nm, measured by powder diffractometry and evaluated by the method of Scherrer, a primary particle size of 0.1 to 0.5 .mu.m, a specific surface according to BET of 5 to 50 m.sup.2 /g and a degree of whiteness of more than 91%, measured using light of a 400 to 700 nm wavelength against barium sulfate analytical reagent as standard of whitness. To prepare this aluminum nitride powder, metallic aluminum and monoamminealuminum chloride [AlCl.sub.3 (NH.sub.3)] are first molten together in an inert gas atmosphere at temperatures above 125.degree. C. and allowed to react with one another with evolution of hydrogen. 8 to 20 g of ammonia are then introduced per hour per mol of monoamminealuminum chloride into the aluminum-containing monoamminealuminum chloride melt at temperatures between 250.degree. and 400.degree. C., aluminum nitride being precipitated as a solid until the conversion of the aluminum is complete. The temperature of the melt is finally raised to more than 400.degree. C.

Aluminum nitride powder and a process for the preparation thereof

A continuous process is indicated for complete removal of organic impurities from and complete decolorization of pre-purified wet-process phosphoric acid which has been purified by an extractive method using an organic solvent, freed from residual hydrofluoric acid by steam stripping and treated with hydrogen peroxide at elevated temperature, which comprises mixing the pre-purified wet-process phosphoric acid and the hydrogen peroxide in a mixing zone at a temperature of from 100.degree. to 200.degree. C., preferably 140.degree. to 160.degree. C., and allowing them to react at this temperature for a further 1 to 4 hours, cooling to from 85.degree. to 90.degree. C. the pre-purified wet-process phosphoric acid treated in this way and pumping it at this temperature with exclusion of air firstly through an activated charcoal bed which has been prepared on the basis of peat and has been steam-activated and has a BET surface area of from 800 to 1000 m.sup.2 /g, and subsequently through a silicon carbide and/or graphite bed while maintaining a pumping rate of less than 0.5 m.sup.3 /h of wet-process phosphoric acid per m.sup.3 of activated charcoal bed.

Continuous process for complete removal or organic impurities from and

The reactivity of phosphorus pentoxide is reduced and its flow behavior improved. To this end, phosphorus pentoxide in the form of its hexagonal modification is annealed over a period of 0.5 to 8 hours at temperatures of 200.degree. to 390.degree. C.

Process for reducing the reactivity and improving the flow behavior of

An aqueous alkali phosphate solution is made. An organic phase is countercurrently mixed with an aqueous phase, the two phases being used in a volume ratio larger than 1:1 and formed aqueous alkali phosphate solution is separated from the remaining organic phase. The two phases are mixed and reacted in a reaction zone comprised of a mixing and separating zone. The organic phase is continuously dispersed in the aqueous phase. A volume excess of aqueous phase is maintained in the mixing zone and the two phases are used in an overall quantity sufficient to provide a volume ratio of organic to aqueous phase of 4:6 to 2:8.

Process for making an alkali phosphate solution

Phosphoric acid solutions are dearsenified by treating them with a sulfide and separating the resulting precipitate from the purified solution. The sulfide is at least one compound of the general formula P.sub.4 S.sub.x in which x stands for a number of 3 to 10.

Process for dearsenifying phosphoric acid solutions

The disclosure relates to a process for making a particulate agent stable to hydrolysis based on free-flowing, pulverulent ammonium polyphosphate by treating the ammonium polyphosphate with a thermosetting, artificial resin being water-insoluble when cured. More specifically, the disclosure provides for the ammonium polyphosphate, an aliphatic alcohol as a diluent, and a melamine/formaldehyde-resin or phenol/formaldehyde-resin to be placed in an autoclave and intimately mixed at room temperature; for the mixture to be heated to a temperature of about 80.degree. to about 180.degree. C. and allowed to remain over a period of 15 to 240 minutes at that temperature and under the pressure corresponding to the vapor pressure of the diluent; for the diluent to be separated and for the product so obtained to be dried.

Process for making pulverulent ammonium polyphosphates stable to

The disclosure relates to a process for defluorinating alkali metal phosphate solutions. To this end, the disclosure provides for an alkali metal phosphate solution neutralized to a pH-value of more than 6 and pre-purified to be stirred at 60.degree. to 120.degree. C. into an alkaline earth metal compound. Alkaline earth metal compounds with a solubility in water of less than 5 g/l are used in the form of particles of which more than 50% have a size of less than 8 .mu.m. After a reaction period of 0.5 to 4 hours, the precipitate obtained is separated from the purified alkali metal phosphate solution.

Process for defluorinating alkali metal phosphate solutions

The invention relates to improving the degree of graphitization of carbon black produced by subjecting hydrocarbons which are liquid or gaseous under normal conditions to a thermal conversion reaction in the presence of oxygen or an oxygen-containing gas and steam, if desired, at temperatures of 1200.degree. to 2000.degree. C. and pressures of 1 to 80 bars. To this end, the carbon black is conveyed downwardly in a quasi-fluid state, within 1 to 5 hours through a sojourn zone in upright position, the sojourn zone being maintained at a temperature of at least 1200.degree. C. The invention relates to an apparatus for carrying out this process, the apparatus comprising a graphite tube; a steel container concentrically surrounding the graphite tube; a feed pipe penetrating into the interior of the graphite tube; a water-cooled discharge means; and a nitrogen feed inlet arranged below the lower end of the graphite tube; the space left between the graphite tube and steel container being occupied by insulating material.

Apparatus for improving the degree of graphitization of carbon black,

Manganese(II)salt solutions containing ammonium salt are made by subjecting a manganese-containing compound to processing treatment with an ammonium salt solution. A boiling temperature of 57.degree.-68.degree. C. is established in the suspension to be subjected to the processing treatment, by application of a vacuum. The ammonium salt solution used contains 0.5-2.5 mol/l diammonium sulfate or 1.0-5.0 mol/l ammonium nitrate.

Process for making manganese (II) salt solutions containing ammonium salt

The disclosure relates to a process for purifying crude, concentrated wet-processed phosphoric acid. To this end, the disclosure provides:

Process for purifying wet-processed phosphoric acid

The disclosure relates to a process for removing organic compounds from wet-processed phosphoric acid with the aid of an adsorbant. To this end the disclosure provides for the acid to be heated to at least 250.degree. C. prior to treating it with the adsorbant. The disclosure also relates to an apparatus for carrying out the process.

Process for removing organic contaminants from wet-processed phosphoric

The disclosure provides for phosphoric acid to be freed in a single process stage from fluorine and organic contaminants. To this end, the disclosure provides for the acid to be introduced into the upper portion of a closed structural element, for it to be treated therein at elevated temperature and pressure with steam flowing countercurrently to the acid, and for the acid so treated to be reacted in the lower portion of the structural element with hydrogen peroxide. The disclosure also provides an apparatus for carrying out the process.

Process for removing fluorine and organic compounds from prepurified wet

The disclosure relates to a process for the discontinuous separation of a solid consisting predominantly of carbon black from its aqueous suspension by filtration. To this end, the disclosure provides for use to be made of a tube pressure filter which is operated under a final pressure of 30 to 100 bars.

Process for separating carbon black from an aqueous suspension

The disclosure relates to a process for separating gallium and indium from an aqueous solution by subjecting this latter to liquid/liquid extraction with the use of certain classes of organylphosphonic acid esters and separating the resulting liquid phases from one another.

Process for separating gallium and indium from aqueous solutions

The disclosure relates to a process for making titanium dioxide concentrates from material containing titanium oxide and iron oxides. More particularly, the titanium oxide-containing material is calcined at temperatures of 870.degree. to 1300.degree. C., and then treated with a chlorine-containing gas at temperatures of 800.degree. to 1300.degree. C., if desired with addition of carbon.

Process for making titanium dioxide concentrates

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Erftstadt, Germany

Gero Heymer