Abstract: 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.

Abstract: 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.

Abstract: 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.

Abstract: 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.

Abstract: 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.

Abstract: 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.

Abstract: 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.

Abstract: 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.

Abstract: 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.

Abstract: The disclosure relates to a process for purifying crude, concentrated wet-processed phosphoric acid. To this end, the disclosure provides:(a) for the organic solvent to be mixed with the starting product in a ratio by volume of more than 4:1 to effect the extraction in a single process step--from the crude wet-processed phosphoric acid--of a quantity of phosphoric acid necessary for 40 to 70 weight % of the P.sub.2 O.sub.5 used to go into the organic phase, and for the resulting aqueous phosphoric acid raffinate to contain at most 28-32 weight % P.sub.2 O.sub.

Abstract: 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.

Abstract: 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.

Abstract: 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.

Abstract: 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.

Abstract: 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.

Abstract: The disclosure relates to a process for removing nitrogen dioxide from off-gas. To this end, the disclosure provides for the off-gas to be intimately contacted with a suspension consisting of red phosphorus and a liquid being inert with respect to red phosphorus, e.g. water.

Abstract: The disclosure relates to a process for removing heavy metal ions and arsenic from wet-processed phosphoric acid, wherein the crude wet-processed phosphoric acid is treated at temperatures between 10.degree. and 100.degree. C. initially with a diorganyldithiosphosphoric acid ester and then with an adsorbent, and the phoshoric acid so purified is separated from the ester and adsorbent. More particularly, the wet-processed phosphoric acid is treated with the diorganyldithiophosphoric acid ester at temperatures higher than 50.degree. C. and with the adsorbent at temperatures lower than 50.degree. C.

Abstract: The present invention relates to a process for recovering uranium from raffinate which is obtained by extracting phosphoric acid from a uranium-containing wet-process phosphoric acid with the aid of organic extractants and separating the resulting organic phosphoric acid extract from residue not taken up by the extract. To this end, the raffinate residue is subjected to thermal treatment and thereby freed from dissolved or emulsified residual extractant. Next, the raffinate is treated with a water-immiscible solvent to extract the uranium, and the extracted uranium is separated from the undissolved raffinate portion.

Abstract: The disclosure relates to a process for after-treating extraction residues, termed raffinates, originating from the extractive decontamination of crude phosphoric acid. To this end, the disclosure provides for the raffinates to be converted to two separate solid matter fractions of differant chemical composition by admixing the raffinates with a calcium compound so as to establish a pH-value of 1.2 up to 2.5. Next, the resulting precipitate consisting essentially of gypsum is filtered off as a first solid matter fraction, and washed with water. The resulting filtrate and the wash water are made into a mixture and predetermined proportions of calcium compound are added so as to obtain, after complete reaction, a fully reacted filter cake with a pH-value of 9 up to 12, the resulting suspension being filtered off at a pH-value of 6 to 8. The filter cake consisting essentially of calcium phosphate is separated as the second solid matter fraction, and allowed to react completely.

Abstract: The disclosure relates to process for removing heavy metal ions, especially cadmium, copper, lead and mercury ions from wet-processed phosphoric acid. To this end, the crude acid is contacted with a mixture consisting of an adsorbent and a diorganyldithiophosphoric acid ester or, after treatment with the ester, the acid is contacted with the adsorbent alone, and the purified phosphoric acid is ultimately separated from the ester and adsorbent.