Hoechst Aktiengesellschaft

Klaus Schrodter

Klaus-Peter Ehlers

Wolfgang Scheibitz

Reinhard Gradl

Gero Heymer

Alexander Maurer

Gunther R Schimmel

Joachim Kandler

Klaus Lehr

Heinz Harnisch

Hasso Spott

Roelof Mulder

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&gt;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.

Process for making phosphoric acid free from titanium

Mineral acids are freed from heavy metals, especially copper, arsenic, antimony and lead by precipitating the metals in sulfide form. To this end, the mineral acid is reacted with hydrogen sulfide or an alkali metal sulfide solution under pressure and with thorough agitation, and formed solid matter is subsequently separated from the mineral acid under the pressure selected. The mineral acid may conveniently by admixed initially with a filter aid and then treated with hydrogen sulfide or the alkali metal sulfide solution.

Process for freeing mineral acids from heavy metals

The disclosure relates to a process for making linear, substantially water-insoluble ammonium polyphosphates of the general formula (NH.sub.4 PO.sub.3).sub.10-1000 by heating and continuously mixing phosphorus pentoxide and ammonium orthophosphate in the presence of ammonia and tempering the resulting reaction product over a period of several hours at 200.degree. to 400.degree. C. in the presence of ammonia. To this end, the phosphorus pentoxide and ammonium orthophosphate are subjected at 50.degree. to 150.degree. C. to the following successive operations which provide

Linear, substantially water-insoluble ammonium polyphosphates and

Iron contained in phosphoric acid solution is reduced from the trivalent to the bivalent oxidation stage. To this end, red phosphorus is used as the reductant and the reduction is effected in the presence of copper.

Process for reducing iron in phosphoric acid solution

The invention relates to the decontamination of wet-processed phosphoric acid with the use of organic solvents in a plurality of extraction zones, of which each is comprised of a mixing zone and a separating zone, the solvent being immiscible or partially miscible with water. Resulting organic phase and the aqueous phase are contacted countercurrently with respect to one another, the organic solvent phase being dispersed in the aqueous phase. To this end, the invention provides for the aqueous phase to be admitted to the mixing zone at the onset of the extraction, and for organic phase and aqueous phase to be continuously admitted in a volume ratio of at least 2.5:1 to the respective extracting zones in an overall quantity sufficient to provide, in the mixing zones of the extraction zones, a volume ratio of organic phase to aqueous phase of at most 1:1, which is maintained therein.

Purification of wet-process phosphoric acid

The invention relates to a process for the purification of wet-processed phosphoric acid with the aid of organic solvents which are immiscible or only partially miscible with water, the sulfate ions being removed by addition of barium compounds. The purification is carried out in an n-stage extraction installation, where n is equal to or greater than 5. The barium compound is added to the phosphoric acid to be purified, and the resulting mixture is fed to the top of the extraction installation, in which the organic solvent phase is dispersed in the aqueous phase. The sulfuric acid is led in counter-current fashion to the phosphoric acid by adding it to one of the stages n=4 to at most n-1.

Process for the purification of wet-processed phosphoric acid

The present invention relates to a mixer/settler-type apparatus for continuous liquid-liquid extraction. The apparatus is comprised of a separating vessel with an inclined bottom portion and an agitator-provided mixing vessel. The mixing vessel is tightly mounted to the inclined bottom portion of the separating vessel, the latter being formed with an upper outlet and a lower outlet and having a level indicator LI for determining phase boundary surface area installed therein. The lower outlet is passed through the separating vessel near its lowermost level and the upper outlet is passed therethrough near its upper end. The level indicator LI is connected to a regulator giving adjustment instructions to a structural element permitting the phase boundary surface area to be established in the separating vessel, distinctly above the upper end of the mixing vessel.

Liquid-liquid extraction apparatus

The invention relates to the production of alkali metal phosphate solutions free of zinc, from phosphoric acid solutions contaminated with zinc. To this end, feed solution is admixed with alkali metal hydroxide or carbonate so as to establish in the resulting suspension a pH-value within the range 8 to 14. Next, resulting suspension is reacted under pressure and with thorough agitation with H.sub.2 S or an alkali metal sulfide solution; and decontaminated alkali metal phosphate solution is separated from solid matter, the pressure being maintained.

Production of alkali metal phosphate solutions free from zinc

The invention relates to a process permitting acid salt residues, hereinafter called raffinates, which are obtained in the decontamination of phosphoric acid by extraction with a solvent, to be converted to solid deposition products, wherein the raffinates are admixed with a quantity of water necessary for them to ensure, after reaction with hydrate of lime or quicklime, the formation of an aqueous filterable suspension. More particularly, the raffinates are admixed with a quantity of hydrate of lime or quicklime necessary for them to ensure, after reaction and filtration of the suspension, the formation of a filter cake having a pH-value within the range 9 to 14. The reaction suspension is filtered as soon as it has assumed a pH-value within the range 5 to 8 and the resulting filter cake is allowed to react completely and deposited.

Conversion of extraction residues originating from phosphoric acid

The invention relates to a process for freeing aqueous phosphoric acid solutions from organic contaminants. To this end, the solutions are admixed and reacted with hydrogen peroxide in the presence of a catalyst consisting of a noble metal or metal oxide being inert with respect to phosphoric acid or of a mixture of said noble metal and metal oxide.

Process for freeing phosphoric acid from organic contaminants

For extracting phosphates with alcohol in the presence of water and a strong mineral acid, with the resultant formation of an alcoholic phosphoric acid solution and an aqueous salt phase, a plurality of mixing settlors are arranged one upon another, so that the bottom outlet for the aqueous salt phase of each mixing settlor serves as the feeder for the next mixing settlor below and the outlet for the alcoholic solution of each settlor is connected with the feed pipe for this solution of the next mixing settlor above. Each mixing settlor is subdivided by means of two partitions into a mixing chamber A, a separating chamber B and a settling chamber C. The said two partitions do not extend to the bottom of the mixing settlor and are arranged so that the three chambers A, B and C communicate with one another.

Apparatus for recovering alcoholic phosphoric acid solutions from acid

Wet-processed phosphoric acid is purified by counter-current extraction with the use of an organic solvent, in which water is partially soluble and which is capable of absorbing phosphoric acid, the organic phosphoric acid extract is separated from residual wet-processed phosphoric acid, unabsorbed by the solvent, and phosphoric acid is recovered from the separated organic phosphoric acid extract. More specifically, the wet-processed phosphoric acid is extracted with the use of a solvent containing more than 0 and less than 50% of water, based on the saturation concentration, and a mineral acid in a quantity corresponding to the quantity, in moles, of cation-bound phosphate in the crude acid.

Solvent extraction purification of wet-processed phosphoric acid

Alcoholic phosphoric acid solutions are produced from acid phosphates or phosphate mixtures in the presence of water and a strong mineral acid by extraction with water. To this end, an aqueous phosphate solution or suspension is contacted countercurrently and thereby mixed with a mixture of at least one alcohol having from 3 to 8 carbon atoms and a strong mineral acid, the alcohol or alcohol mixture and the phosphate solution or suspension being used in a ratio by volume of 2:1 to 20:1, and the mineral acid being used in the quantity just necessary to transform the phosphates approximately quantitatively to phosphoric acid. The alcohol or alcohol mixture, mineral acid and phosphate solution or suspension contain the quantity of water necessary to ensure the formation of a mixture consisting of an alcoholic phase and a separate flowable salt phase, which is separated from the alcoholic phase.

Process and apparatus for recovering alcoholic phosphoric acid solutions

Wet-processed phosphoric acid is decontaminated. To this end, the phosphoric acid and an organic solvent, which is partially miscible with water and capable of absorbing phosphoric acid, are contacted countercurrently with respect to one another. The resulting organic phosphoric acid solution is separated from contaminants unabsorbed by the solvent, termed primary raffinate, decontaminated phosphoric acid is recovered either in the form of free acid by re-extracting the organic phosphoric acid solution with water, or in the form of an alkali metal phosphate by reacting the organic phosphoric acid solution with an alkali, and the primary raffinate is treated countercurrently with a solvent containing a mineral acid. More specifically, the organic phosphoric acid extract, which orginates from the primary raffinate treatment and contains more than 0 up to at most 10 weight% of water, is mixed with an anhydrous solvent in a ratio by weight necessary to ensure the formation of a mixture containing more than 0 and less than 50% of water than would correspond to the saturation concentration of water in the solvent; and the mixture is contacted countercurrently with the phosphoric acid which is to be decontaminated.

Decontamination of wet-processed phosphoric acid

Blends of crystalline zeolites and sodium triphosphate are made. To this end, a zeolite suspension is spray-dried jointly with an aqueous sodium orthophosphate solution or suspension, in which the molar ratio of Na to P necessary to produce zeolite-free sodium triphosphate containing Na and P in a theoretical ratio of 1.66 is reduced by decrements of 0.01% per each 10% by weight proportion of zeolite in the blend. The zeolite suspension is sprayed separately from the orthophosphate solution or suspension at a separation necessary for the resulting zeolite particles to dry superficially and for the resulting phosphate particles to undergo at least partial condensation, and the superficially dry particles are contacted with the at least partially condensed particles.

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Cologne, Germany

Klaus Schrodter