Hoechst Aktiengesellschaft

Wolfgang Scheibitz

Klaus-Peter Ehlers

Klaus Schrodter

Gero Heymer

Bernhard Wojtech

Reinhard Gradl

Klaus P Ehlers

Hasso Spott

Heribert Tetzlaff

Wilhelm Lendle

A process is disclosed for the separation of halogenated hydrocarbons from concentrated hydrochloric acid, which contains 10 to 37% by weight of hydrogen chloride. The hydrochloric acid is freed from the halogenated hydrocarbons in an extraction with paraffins having more than 7 carbon atoms, or with paraffin waxes having dropping points from 70.degree. to 160.degree. C. or with paraffin/paraffin wax mixtures, preferably in a continuous counterflow extraction or cross-flow extraction.

Process for the separation of halogenated hydrocarbons from hydrochloric

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 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

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

Contaminated phosphoric acid, particularly wet-processed phosphoric acid, is purified by extracting it from its aqueous solution by means of an organic solvent, which is immiscible or partially miscible with water and in which phosphoric acid is soluble, separating the phosphoric acid being dissolved in the organic solvent from extraction residue, and recovering the phosphoric acid from the organic solution. The aqueous phosphoric acid is more particularly mixed in a reaction zone, in a ratio by volume within the range 1:0.3 to 1:30, with a solvent having a boiling point higher than that of water or higher than that of the resulting water solvent-azeotrope, the phosphoric acid/solvent-mixture is heated to temperatures between the boiling point of water or of the said azeotrope and that of the solvent until distillation of substantially all uncombined water originally present in the mixture, and residue and resulting anhydrous phosphoric acid solution in the organic solvent are separated.

Purification of phosphoric acid by means of organic solvents

Phosphoric acid is purified. To this end, it is dissolved in an organic solvent completely miscible with water. More particularly, the phosphoric acid is mixed with a solvent having a boiling point higher than that of water or higher than that of the resulting azeotrope; the resulting solution is heated to temperatures between the boiling point of water or the azeotrope and that of the solvent for as long a period as necessary to distillatively free the solution from the bulk of uncombined water therein; and the phosphoric acid solution is separated from residue.

Purification of phosphoric acid

Polyphosphoric acid is dearsenicated by placing the polyphosphoric acid in a reactor; adding a phosphorus oxo-compound containing phosphorus in the monovalent or trivalent electropositive oxidation stage; heating the resulting mixture to effect disproportionation of the phosphorus oxo-compound; and removing the resulting off-gas having arsenic therein.

Process for the dearsenication of polyphosphoric acid

Waste material consisting substantially of contaminated phosphorous acid is utilized. To this end, the phosphorous acid is introduced, with agitation into a liquid phase. Liquid phase and phosphorous acid are maintained in a ratio by volume between 1:1 and 10:1. The liquid phase is placed in a reactor, maintained between 250.degree. and 400.degree.C and selected from a phosphoric acid of the general formula H.sub.n.sub.+2 P.sub.n O.sub.3n.sub.+1, in which n substantially stands for a number between 1 and 5. Resulting hydrogen phosphide is removed. In the event of continuous operation, newly formed liquid phase is removed from the reactor, at the same rate as it is being formed.

Process utilizing waste material consisting substantially of phosphorous

Contaminated wet-processed phosphoric acid is purified. To this end, the wet-processed phosphoric acid is mixed with one or more organic solvents, in which water is partially soluble, the organic solvent(s) is (are) separated from unabsorbed wet-processed phosphoric acid portions, and phosphoric acid is recovered from the organic solvent(s) so separated. The organic solvent(s) are more particularly used in the form of anhydrous material and at least in the quantity necessary to ensure dissolution (a) of the overall quantity of phosphoric acid contained in the wet-processed phosphoric acid and (b) of the free water therein.

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Hurth-Knapsack, Germany

Wolfgang Scheibitz