Abstract: For working up concentrated, preferably partially condensed phosphoric acid which is contaminated with organic components, the phosphoric acid is first thoroughly mixed with fine-grained sand in a weight ratio of (0.5 to 1.5):1. Then, to neutralize the mixture, a basic, oxygen-containing calcium compound is added, while the thorough mixing is continued, until a 10% aqueous suspension of the mixture to which the calcium compound has been added has a pH between 5 and 11. Finally, the mixture which contains the calcium compound is commminuted after cooling.

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: A process is provided for working up dusts which have been precipitated electrostatically from the gas mixture composed essentially of carbon monoxide and phosphorus vapor produced in the electrothermal production of yellow phosphorus, which process comprises converting the dusts into a calcinate at 300.degree. to 800.degree. C. under oxidizing conditions in a first step, leaching the calcinate with phosphoric acid in a second step, adjusting the pH of the solution in phosphoric acid to 0 to 1.5 with sodium hydroxide solution in a third step, precipitating the sulfides of lead, copper and cadmium from the partially neutralized solution in phosphoric acid by adding sulfide and filtering them off in a fourth step, adjusting the pH of the filtered, partially neutralized solution in phosphoric acid to about 1.5 to 5.

Abstract: The purification of phosphorous acid which is formed in halogenations of hydrocarbon derivatives using phosphorus trihalides is carried out in the context of preparing phosphorous acid in a reaction zone by reacting a mixture of phosphorus trichloride and water which has been finely divided by means of steam at temperatures between 150.degree. and 200.degree. C. in the gas phase. In this process, the liquid reaction product drains into a concentrating evaporation zone which has a downstream first separation zone. Inert gas is introduced to the lower part of the first separation zone. A melt is withdrawn from the first separation zone into a crystallizing zone. The waste gases from the reaction zone are treated with a washing liquid in a second separation zone before being passed into the atmosphere. The washing liquid used is an aqueous solution of never-purified phosphorous acid, which can have been prepurified by hydrolysis and stripping.

Abstract: Phosphoric acid substantially free from titanium is made from the organic extract obtained by subjecting crude phosphoric acid containing titanium to extractive purification with an organic solvent immiscible or only partially miscible with water. To this end, the organic extract is scrubbed in a scrubbing zone with a stage number of n>4 by introducing the crude extract into stage 1 and scrubbing it countercurrently with an aqueous alkaline solution in one of stages 2 to n-2 and with pure scrubbing water in stage n.

Abstract: Crude phosphoric acid is made by subjecting crude phosphate ore containing sulfide to processing treatment with a mineral acid in a closed system comprised of a processing reactor, a filtering zone and an off-gas scrubbing zone. To this end, a soluble compound of a metal forming difficultly soluble sulfides in the respective acid medium is added either(A) during the processing operation the phosphate ore is subjected to or(B) during the scrubbing operation the off-gas is subjected toand the resulting sulfide precipitate is filtered off in case (A) together with further matter precipitated during the processing operation and, in case (B) separated from the scrubbing liquid.

Abstract: Hexagonal phosphorus pentoxide of diminished reactivity is made by burning liquid yellow phosphorus with a mixture of dry air and pure oxygen inside a combustion zone with the resulting formation of a gas stream containing phosphorus pentoxide; next, the gas stream coming from the combustion zone is passed initially through an intermediary zone indirectly cooled by means of fluidized matter and then through a condensing zone fitted with an immersion tube indirectly cooled by means of fluidized matter; the gas stream is passed through the immersion tube at a mean temperature of 450.degree. to 600.degree. C. and allowed to remain in the immersion tube over a period of 2 to 5 seconds.

Abstract: An aqueous solution of hexafluorosilicic acid containing 2 to 15 wgt % H.sub.2 SiF.sub.6 is worked up. To this end, the solution is admixed with particulate CaCO.sub.3 or Ca(OH).sub.2 consisting to an extent of at least 70% of particles having a size of more than 8 .mu.m, but to an extent of at most 15% of particles having a size of more than 2 mm, or with CaCO.sub.3 in admixture with CaO or Ca(OH).sub.2. The calcium compound is used in a quantity sufficient to establish a molar ratio of Ca.sup.2+ /SiF.sub.6.sup.2- of 2.8 to 3.5, and the reaction is effected at a temperature higher than 50.degree. C. After a period of 0.6 to 2.5 hours, the reaction product is filtered.

Abstract: Residue obtained upon the removal of heavy metal contaminants from crude phosphoric acid by means of a dialkyldithiophosphoric acid ester and adsorbent is worked up into ecologically reliable solid matter and into a heavy metal concentrate. The solid matter and heavy metal concentrate are separated from one another by successive mechanical and chemical treatment. The sequential order of these two operational steps can be inversed.

Abstract: Wet process phosphoric acid is freed from heavy metal ions, especially from ions of cadmium, copper, mercury, lead and arsenic and optionally also from organic compounds and sulfuric acid. To this end, the phosphoric acid is contacted with a diorganyldithiophosphoric acid ester and an adsorbent, if desired. Prior to or after said treatment with the ester, the phosphoric acid is admixed with a reductant. The adsorbent, if any is used alone or in combination with an alkaline earth metal compound soluble in phosphoric acid.

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: Wet-process phosphoric acid is made by subjecting a phosphate ore to processing treatment with a mineral acid resulting in the formation of a processed suspension. The formation of silicofluorides is obviated by adding, either to the phosphate ore or the processed suspension, a quantity of an aluminum compound soluble in phosphoric acid sufficent for the processed suspension to present an aluminum concentration of 0.3 to 1.0 wgt %, based on P.sub.2 O.sub.5.

Abstract: The disclosure relates to a process for making alkali metal phosphate solutions containing little fluorine from pre-purified alkali metal phosphate solutions obtained from crude phosphoric acid by extracting the acid with an organic solvent being immiscible or only partially miscible with water, scrubbing the crude extract with water or an alkali metal solution, re-extracting the phosphoric acid from the scrubbed extract with the use of an aqueous alkali metal solution while establishing an alkali metal/P-molar ratio equal to or larger than 1:1, and separating the resulting organic phase from the pre-purified alkali metal phosphate solution obtained.To this end, the disclosure provides:(a) for the pre-purified alkali metal phosphate solution to be stirred at 60.degree.-120.degree. C. into a compound of an alkaline earth metal Me.sup.2+ with a solubility in water at 20.degree. C. of more than 0.01 mol Me.sup.

Abstract: Wet-process phosphoric acid prepurified by liquid/liquid extraction with an organic solvent is decontaminated. To this end, the prepurified acid is first freed from residual extractant, then stripped with steam or hot gas, contacted with a dialkyldithiophosphoric acid ester and a fine particulate adsorbent, and liquid phase material is ultimately treated with steam and hydrogen peroxide.

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 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 reducing the fluorine content in wet-processed phosphoric acid. To this end, the disclosure provides for an acid extract in an organic solvent to be treated with an at least 45 weight % suspension of aluminum hydroxide of which 99% consist of particles with a size of less than 1 .mu.m, the balance consisting of particles with a size of less than 10 .mu.m.

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 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.