WO2013133684A1 - Process for purifying phosphoric acid by nanofiltration - Google Patents

Process for purifying phosphoric acid by nanofiltration Download PDF

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Publication number
WO2013133684A1
WO2013133684A1 PCT/MA2013/000003 MA2013000003W WO2013133684A1 WO 2013133684 A1 WO2013133684 A1 WO 2013133684A1 MA 2013000003 W MA2013000003 W MA 2013000003W WO 2013133684 A1 WO2013133684 A1 WO 2013133684A1
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WO
WIPO (PCT)
Prior art keywords
phosphoric acid
membrane
function
solution
acid
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PCT/MA2013/000003
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French (fr)
Inventor
Khaoula KHALESS
Abdelaali Kossir
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Ocp Sa
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Application filed by Ocp Sa filed Critical Ocp Sa
Priority to AU2013228080A priority Critical patent/AU2013228080B2/en
Priority to CA2870066A priority patent/CA2870066C/en
Priority to RU2014140320A priority patent/RU2625872C2/en
Publication of WO2013133684A1 publication Critical patent/WO2013133684A1/en
Priority to ZA2014/07233A priority patent/ZA201407233B/en

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Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D67/00—Processes specially adapted for manufacturing semi-permeable membranes for separation processes or apparatus
    • B01D67/0081—After-treatment of organic or inorganic membranes
    • B01D67/0093—Chemical modification
    • B01D67/00931—Chemical modification by introduction of specific groups after membrane formation, e.g. by grafting
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
    • C01B25/00—Phosphorus; Compounds thereof
    • C01B25/16—Oxyacids of phosphorus; Salts thereof
    • C01B25/18—Phosphoric acid
    • C01B25/234—Purification; Stabilisation; Concentration
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D61/00—Processes of separation using semi-permeable membranes, e.g. dialysis, osmosis or ultrafiltration; Apparatus, accessories or auxiliary operations specially adapted therefor
    • B01D61/02—Reverse osmosis; Hyperfiltration ; Nanofiltration
    • B01D61/027—Nanofiltration
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D61/00—Processes of separation using semi-permeable membranes, e.g. dialysis, osmosis or ultrafiltration; Apparatus, accessories or auxiliary operations specially adapted therefor
    • B01D61/02—Reverse osmosis; Hyperfiltration ; Nanofiltration
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D67/00—Processes specially adapted for manufacturing semi-permeable membranes for separation processes or apparatus
    • B01D67/0081—After-treatment of organic or inorganic membranes
    • B01D67/0093—Chemical modification
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D69/00—Semi-permeable membranes for separation processes or apparatus characterised by their form, structure or properties; Manufacturing processes specially adapted therefor
    • B01D69/02—Semi-permeable membranes for separation processes or apparatus characterised by their form, structure or properties; Manufacturing processes specially adapted therefor characterised by their properties
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D71/00—Semi-permeable membranes for separation processes or apparatus characterised by the material; Manufacturing processes specially adapted therefor
    • B01D71/06—Organic material
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
    • C01B25/00—Phosphorus; Compounds thereof
    • C01B25/16—Oxyacids of phosphorus; Salts thereof
    • C01B25/18—Phosphoric acid
    • C01B25/22—Preparation by reacting phosphate-containing material with an acid, e.g. wet process
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D2323/00—Details relating to membrane preparation
    • B01D2323/10—Specific pressure applied
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D2323/00—Details relating to membrane preparation
    • B01D2323/46—Impregnation
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D2325/00—Details relating to properties of membranes
    • B01D2325/16—Membrane materials having positively charged functional groups
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D2325/00—Details relating to properties of membranes
    • B01D2325/30—Chemical resistance

Definitions

  • the present invention relates to a process for purifying a solution of phosphoric acid, especially a solution of phosphoric acid wet.
  • the wet phosphoric acid is obtained industrially in the form of a solution by attacking natural phosphate with a strong acid such as hydrochloric acid, nitric acid and / or sulfuric acid.
  • the phosphoric acid solution contains metallic impurities (especially Fe, Al, Cd, Cu * Zn, Pb, U, etc.) at varying concentrations.
  • Nanofiltration is a process in which a fluid to be purified under pressure is passed through a membrane, which retains the molecules contained in the fluid whose molar mass is greater than the cut-off point of ; the, membrane.
  • nanofiltration is rather widespread in aqueous media, it is still little used in concentrated acid medium because of the limited number of membranes able to withstand the entire pH range and the high temperature that can be applied during purification.
  • WO 01/89654 discloses a membrane for nanofiltration claimed as stable in an acidic medium comprising a polymer matrix stable in a particular acidic medium based on polysulfonamides. Such a particular membrane is not suitable for industrial use for the preparation of phosphoric acid.
  • No. 5,945,000 proposes a process for the purification of phosphoric acid by a polyamide-based membrane, in which, to prolong the life of the membrane, the purification is carried out at a temperature of between 0 and 30 ° C.
  • the lifetime of the membranes remains limited to about 125 days.
  • An object of the invention is to define a process for purifying a phosphoric acid solution in which the lifetime of the organic nanofiltration membranes is longer, typically of the order of one year of continuous use. , while maintaining, during this period, a high performance in terms of flow and abatement.
  • Another object of the invention is to propose. improved organic nanofiltration membranes for the implementation of this process.
  • a method for purifying a phosphoric acid solution by an organic nanofiltration membrane on which at least one hydrosubstituted polymer is adsorbed comprising at least one amine function, an aromatic amine function, a functional function. acid and / or an alcohol function.
  • Said phosphoric acid solution to be purified is preferably derived from the action of a strong acid on natural phosphate.
  • the impurities to be removed from the solution are therefore essentially of a mineral nature, the impurities may be metallic or non-metallic.
  • said at least one adsorbed hydrosubstituted polymer has a molar mass of between 100 and 40,000 g / mol.
  • the concentration of the phosphoric acid in the solution to be purified is advantageously between 10 and 45% P 2 0 5 , preferably between 25 and 30% P 2 0 5 .
  • a step of treating the phosphoric acid solution to remove the solid and organic materials is implemented, before the first filtration step, a step of treating the phosphoric acid solution to remove the solid and organic materials.
  • the phosphoric acid solution has a solids content of less than 1%, preferably less than or equal to 0.7% and an organic carbon content of less than 1000 ppm, preferably less than or equal to equal to 300 ppm.
  • the cutoff threshold of said nanofiltration membrane is between 150 and 1000 g. mol "1 .
  • the organic nanofiltration membrane is a polyethersulfone or polyamide / polysulfone, positively charged in acidic medium *.
  • the water-soluble polymer is chosen from the following polymers: polyethylimine (PEI), polyacrylic acid (PAA), polyvinyl alcohol (PVA) and polyvinylpyridine (PV4P)
  • Another subject relates to a functionalized organic nanofiltration membrane, especially for the purification of a phosphoric acid solution, comprising an organic nanofiltration membrane on which is adsorbed at least one water-soluble polymer comprising at least one amine function, an amine function aromatic, an acid function and / or an alcohol function.
  • said at least one adsorbed water-soluble polymer has a molar mass of between 100 and 40,000 g / mol.
  • Another subject of the invention relates to a process for producing a functionalized organic nanofiltration membrane, said process comprising an adsorption step, on an organic nanofiltration membrane, of at least one water-soluble polymer comprising at least one amine function , an aromatic amine function, an acid function and / or an alcohol function.
  • said at least one water-soluble polymer has a molar mass of between 100 and 40,000 g / mol.
  • the adsorption step comprises bringing said membrane into contact with a solution of said water-soluble polymer in a strong acid.
  • Said strong acid may comprise hydrochloric acid, phosphoric acid, nitric acid and / or sulfuric acid.
  • the concentration of water-soluble polymer in said solution is advantageously between 80 and 400 ppm, preferably between 100 and 300 ppm.
  • the adsorption step is carried out at a temperature of between 25 and 100 ° C., preferably between 50 and 80 ° C., and under an absolute pressure of between 2 and 30 bar, preferably between 5 and 15 bar. .
  • the invention relates to a purification method of a phosphoric acid solution comprising at least one filtration step of phosphoric acid with an organic nanofiltration membrane on which is adsorbed ⁇ at least one water-soluble polymer comprising at least one amine function , an aromatic amine function, an acid function and / or an alcohol function.
  • the phosphoric acid solution is circulated over a membrane, preferably tangentially to said membrane.
  • a permeate of purified phosphoric acid whose volume is a fraction y VO of the initial VO volume is collected.
  • the coefficient VO is generally between 0.4 and 0.8, advantageously between 0.6 and 0.8.
  • the concentration of the phosphoric acid in the solution is between 10 and 45% P 2 O 5, preferably between 25 and 30% P 2 O 5.
  • the process according to the invention can be used for any solution of phosphoric acid, whatever its origin.
  • the phosphoric acid in solution is advantageously phosphoric acid called "wet” that is to say obtained by the action of a strong acid, such as hydrochloric acid, nitric acid and / or sulfuric acid on the natural phosphate.
  • a strong acid such as hydrochloric acid, nitric acid and / or sulfuric acid on the natural phosphate.
  • the phosphoric acid obtained in solution is then purified according to the invention.
  • the phosphoric acid solution obtained by the action of the strong acid on the natural phosphate also called “solution of crude phosphoric acid”
  • the method comprises a first step of treating the crude phosphoric acid solution so as to remove both the solids and the organic materials, which could irreversibly clog the membrane. nanofiltration used later.
  • the phosphoric acid solution which will then be purified according to the invention has a solid particles content of less than 1%, preferably less than or equal to 0.7%, and a lower organic carbon content. at 1000 ppm, preferably less than or equal to 300 ppm.
  • the phosphoric acid solution thus treated is then subjected to two successive filtration steps by means of a membrane.
  • the process for purifying a phosphoric acid solution comprises two successive stages of filtration by a membrane.
  • the phosphoric acid solution is circulated over an NF1 membrane, preferably tangentially to said membrane.
  • a first permeate P1 of purified phosphoric acid whose volume is a fraction y1 V0 of the initial volume V0 is collected.
  • the coefficient y1 is advantageously between 0.6 and 0.8.
  • said first permeate P1 is circulated over an NF2 membrane, preferably tangentially to said membrane.
  • the NF2 membrane used in the second step may be the same as the NF1 membrane used in the first step where Well be a different membrane but having a similar chemical structure.
  • a second permeate P2 of purified phosphoric acid whose volume is a fraction y2 V0 of the initial volume V0 is thus collected.
  • the coefficient V0 is typically between 0.4 and 0.8.
  • the second permeate P2 is characterized by a lower metal impurity composition than that of the first permeate PL
  • the purified phosphoric acid according to the invention can be upgraded, depending on its content, either as a food acid or as the result of an intermediate purification step, before the finishing treatments (for example, a liquid-liquid extraction). .
  • the invention also relates to a functionalized organic nanofiltration membrane comprising an organic nanofiltration membrane on which is adsorbed at least one water-soluble polymer comprising at least one amine function, an aromatic amine function, an acid function and / or an alcohol function.
  • Said membrane is obtained by modifying an organic nanofiltration membrane of known type, called the initial membrane.
  • nanofiltration membranes that can be used to nanofilter solutions.
  • the initial membrane is a stable membrane in an acid medium.
  • the initial membrane has a cut-off threshold adapted according to the degree of purity that it is desired to achieve.
  • the cutoff threshold is 150 g. mol “1 , 300 g mol -1 , or 1000 g. mol “1 or any value between 150 and 1000 g. mol “ 1 .
  • Suitable membranes include, but are not limited to, polyethylene / polysulfone or other positively charged organic polyethersulfone membranes, in particular the membranes marketed under the trademarks MP, NF, Desal, or PES respectively by the Koch companies. , Filmtec, Osmonics and Nadir.
  • the modification made to the initial membrane comprises the adsorption of at least one water-soluble polymer comprising at least one amine function, an aromatic amine function, an acid function and / or an alcohol function.
  • Said at least one water-soluble polymer may be adsorbed alone or as a mixture, the different polymers may differ in the length of their chain and / or the function they carry.
  • said at least one adsorbed water-soluble polymer has a molar mass of between 100 and 40,000 g / mol.
  • the water-soluble polymers used may be linear and / or aromatic and have at least one amine function (primary, secondary or tertiary), an acid function, an alcohol function, an aromatic amine function or the like.
  • Such water-soluble polymers are known to those skilled in the art, more particularly the following polymers: Polystabil®, Polyethylinimine (PEI), commercially available under the name PolyminP PIP, polyacrylic acid (PAA), polyvinyl alcohol (PVA) and Polyvin4 Pyridine (PV4P) can be used.
  • Polystabil® Polyethylinimine (PEI)
  • PEI Polyethylinimine
  • PAA polyacrylic acid
  • PVA polyvinyl alcohol
  • PV4P Polyvin4 Pyridine
  • the initial membrane is brought into contact with a solution of said water-soluble polymer in a strong acid.
  • a conventional method of contacting the water-soluble polymer in solution with the membrane comprises circulating said solution through the nanofiltration membrane.
  • Said strong acid typically comprises hydrochloric acid, phosphoric acid, nitric acid and / or sulfuric acid.
  • the strong acid consists of hydrochloric acid and / or phosphoric acid.
  • the concentration of water-soluble polymer in said solution is between 80 and 400 ppm, preferably between 100 and 300 ppm.
  • the said solution is brought into contact with the initial membrane at a temperature of between 25 and 100 ° C., preferably between 50 and 80 ° C., and under an absolute pressure of between 2 and 30 bar, preferably between 5 and 15 bar.
  • the solution is filtered through the membrane and the permeate is recirculated until the desired adsorption is obtained.
  • the duration of this contacting is advantageously at least 1 hour, more preferably at least 3 hours.
  • the modified membrane is cleaned with distilled water.
  • the electrical conductivity of the water used for cleaning is periodically measured and the cleaning is stopped when the conductivity of the water stabilizes.
  • the adsorption of polymer on the membrane is reduced by a reduction of 24 to 80% in the hydraulic permeability of the initial membrane.
  • the membrane thus modified is stable at a very acidic pH and has a lifetime greater than 6 months.
  • this membrane has the advantage of allowing the implementation of the purification process at low temperature, that is to say in a range between 25 and 40 ° C.
  • the process for preparing the membrane described above thus makes it possible to significantly improve the performance of the nanofiltration membranes currently on the market.
  • the purification process has the advantage of not generating secondary effluent (excluding cleaning solutions Equipment ); it does not pose a risk to the environment.
  • the purified phosphoric acid obtained by said process corresponds to different grades and can be used for different purposes.
  • the advantage of the acid used is that it has a low concentration of molybdenum, which causes the decrease in the use of NaHS used for the desarriage.
  • Purified phosphoric acid may also find application in the production of food grade acid.
  • the invention makes it possible to produce pure phosphoric acid at 30% P 2 O 5, which avoids having to dilute phosphoric acid to 60% P 2 O 5.
  • This is a batch process, batch fed, that is to say that is purified successively separate volumes of crude phosphoric acid.
  • the membrane is an organic nanofiltration membrane modified by adsorption of a single water-soluble polymer which has a long polymerization ⁇ chain and an amine function.
  • the initial membrane serving as a basis for this modification has a cutoff threshold of 1000 g.mol -1 .
  • the permeability of the phosphoric acid purified at 40 ° C. by the modified membrane is 0.73 l / h / m 2 / bar.
  • the membrane used in the invention is stable for more than one year of continuous use.
  • Table 1 shows the concentrations of metallic and non-metallic impurities obtained in the purified phosphoric acid.
  • Example 2 a purification process similar to that of Example 1 is used, but with a different membrane.
  • the membrane is an organic nanofiltration membrane modified by the adsorption of a mixture of two water-soluble polymers, which differ in their function and / or the length of their chain.
  • the initial membrane serving as a basis for this modification has a cutoff threshold of 300 g. mol "1 and has an active skin of polyamide / polysulfone.
  • the permeability of the phosphoric acid purified at 40 ° C. by the modified membrane is 0.23 l / h / m 2 / bar.
  • Table 2 shows the concentrations of metallic and nonmetallic impurities obtained in the purified phosphoric acid.

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  • Chemical Kinetics & Catalysis (AREA)
  • Engineering & Computer Science (AREA)
  • Organic Chemistry (AREA)
  • Inorganic Chemistry (AREA)
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Abstract

The invention relates to a process for purifying a phosphoric acid solution, comprising a step of filtration of the phosphoric acid using a nanofiltration membrane, in which the nanofiltration membrane is an organic nanofiltration membrane on which is absorbed at least one water-soluble polymer comprising at least one amine function, one aromatic amine function, one acid function and/or one alcohol function. The invention also relates to a process for manufacturing said membrane, comprising a step of absorption, on an organic nanofiltration membrane, of at least one water-soluble polymer comprising at least one amine function, one aromatic amine function, one acid function and/or one alcohol function.

Description

PROCEDE DE PURIFICATION D'ACIDE PHOSPHORIQUE PAR NANOFILTRATION  PROCESS FOR THE PURIFICATION OF PHOSPHORIC ACID BY NANOFILTRATION
DOMAINE DE L'INVENTION FIELD OF THE INVENTION
La présente invention concerne un procédé de purification d'une solution d'acide phosphorique, notamment une solution d'acide phosphorique de voie humide. The present invention relates to a process for purifying a solution of phosphoric acid, especially a solution of phosphoric acid wet.
ARRIERE PLAN DE L'INVENTION BACKGROUND OF THE INVENTION
L'acide phosphorique de voie humide est obtenu industriellement sous forme d'une solution par attaque de phosphate naturel par un acide fort tel que de l'acide chlorhydrique, de l'acide nitrique et/ou de l'acide sulfurique. The wet phosphoric acid is obtained industrially in the form of a solution by attacking natural phosphate with a strong acid such as hydrochloric acid, nitric acid and / or sulfuric acid.
En fonction de l'origine du phosphate naturel, la solution d'acide phosphorique contient des impuretés métalliques (notamment Fe, Al, Cd, Cu* Zn, Pb, U, etc.) à des concentrations variables. Depending on the origin of the natural phosphate, the phosphoric acid solution contains metallic impurities (especially Fe, Al, Cd, Cu * Zn, Pb, U, etc.) at varying concentrations.
Ces impuretés peuvent être gênantes selon la destination de l'acide phosphorique ainsi préparé. These impurities can be troublesome depending on the purpose of the phosphoric acid thus prepared.
Il est donc connu de procéder à une purification de la solution d'acide phosphorique de voie humide. It is therefore known to carry out a purification of the wet phosphoric acid solution.
Différentes techniques ont été développées à cet effet, parmi lesquelles on peut citer la précipitation, la cristallisation, l'extraction liquide-liquide et l'échange d'ions. Various techniques have been developed for this purpose, among which include precipitation, crystallization, liquid-liquid extraction and ion exchange.
Bien qu'étant très économique, la précipitation présente l'inconvénient de ne s'appliquer qu'à certaines impuretés, de nécessiter plusieurs réactifs différents et de générer une grande quantité de boues. Although very economical, the precipitation has the disadvantage of only applying to certain impurities, requiring several different reagents and generating a large amount of sludge.
Les techniques actuelles basées sur une filtration par membrane, telles que la nanofiltration et l'osmose inverse, peuvent être employées comme traitement de finition de l'acide phosphorique mais ne permettent, pas à l'heure actuelle, d'atteindre une qualité pure. La nanofiltration est un procédé dans lequel on fait passer un fluide à purifier sous pression à travers une membrane, qui retient les molécules contenues dans le fluide dont la masse molaire est supérieure au seuil de coupure de;la,membrane. Current techniques based on membrane filtration, such as nanofiltration and reverse osmosis, can be used as a finishing treatment for phosphoric acid but do not currently achieve pure quality. Nanofiltration is a process in which a fluid to be purified under pressure is passed through a membrane, which retains the molecules contained in the fluid whose molar mass is greater than the cut-off point of ; the, membrane.
Cependant, si la nanofiltration est assez répandue en milieu aqueux, elle est encore peu utilisée en milieu acide concentré en raison du nombre limité de membranes aptes à résister à toute la gamme de pH et à la température élevée qui peut être appliquée pendant la purification. However, although nanofiltration is rather widespread in aqueous media, it is still little used in concentrated acid medium because of the limited number of membranes able to withstand the entire pH range and the high temperature that can be applied during purification.
En effet, soit les membranes de nanofiltration organiques connues sont chimiquement stables mais ne permettent pas l'obtention de solutions purifiées, soit elles ne sont pas chimiquement stables en présence d'acide et présentent donc une durée de vie très courte et ne permettent pas une exploitation industrielle de cette technologie dans des conditions économiques acceptables. Indeed, either the known organic nanofiltration membranes are chemically stable but do not allow to obtain purified solutions, or they are not chemically stable in the presence of acid and therefore have a very short life and do not allow a industrial exploitation of this technology under acceptable economic conditions.
Ainsi, des travaux de MP Gonzales et al [2] montrent qu'une membrane de nanofiltration commercialisée sous le nom de DS5-DL par la société Osmonics procure une bonne purification d'une solution d'acide phosphorique jusqu'à'8 M. Cependant, cette membrane n'est pas stable en milieu acide concentré. Thus, work by MP Gonzales et al [2] shows that a nanofiltration membrane marketed under the name of DS5-DL by Osmonics provides a good purification of a phosphoric acid solution up to 8 M. However, this membrane is not stable in concentrated acid medium.
WO 01/89654 décrit une membrane pour nanofiltration revendiquée comme stable en milieu acide comprenant une matrice polymère stable en milieu acide particulière à base de polysulfonamides. Une telle membrane particulière n'est pas adaptée à un usage industriel pour la préparation d'acide phosphorique. WO 01/89654 discloses a membrane for nanofiltration claimed as stable in an acidic medium comprising a polymer matrix stable in a particular acidic medium based on polysulfonamides. Such a particular membrane is not suitable for industrial use for the preparation of phosphoric acid.
US 5,945,000 propose un procédé de purification d'acide phosphorique par une membrane à base de polyamide, dans lequel, pour prolonger la durée de vie de la membrane, on met en œuvre la purification à une température comprise entre 0 et 30°C environ. No. 5,945,000 proposes a process for the purification of phosphoric acid by a polyamide-based membrane, in which, to prolong the life of the membrane, the purification is carried out at a temperature of between 0 and 30 ° C.
Cependant, la durée de vie des membranes reste limitée à 125 jours environ. However, the lifetime of the membranes remains limited to about 125 days.
Un but de l'invention est de définir un procédé de purification d'une solution d'acide phosphorique dans lequel la durée de vie des membranes de nanofiltration organiques soit plus longue, typiquement de l'ordre d'une année d'utilisation en continu, tout en conservant, sur cette période, une performance élevée en termes de flux et d'abattement. An object of the invention is to define a process for purifying a phosphoric acid solution in which the lifetime of the organic nanofiltration membranes is longer, typically of the order of one year of continuous use. , while maintaining, during this period, a high performance in terms of flow and abatement.
Un tel procédé doit en outre permettre la fabrication de différents grades d'acide phosphorique. Un autre but de l'invention est de proposer. desjriembranes de nanofiltration organiques améliorées pour la mise en œuvre de ce procédé. Such a process must also allow the manufacture of different grades of phosphoric acid. Another object of the invention is to propose. improved organic nanofiltration membranes for the implementation of this process.
BREVE DESCRIPTION DE L'INVENTION BRIEF DESCRIPTION OF THE INVENTION
Conformément à l'invention, il est proposé un procédé de purification d'une solution d'acide phosphorique par une membrane de nanofiltration organique sur laquelle est adsorbé au moins un polymère hydrosoiubie comprenant au moins une fonction aminé, une fonction aminé aromatique, une fonction acide et/ou une fonction alcool. According to the invention, there is provided a method for purifying a phosphoric acid solution by an organic nanofiltration membrane on which at least one hydrosubstituted polymer is adsorbed comprising at least one amine function, an aromatic amine function, a functional function. acid and / or an alcohol function.
Ladite solution d'acide phosphorique à purifier est de préférence issue de l'action d'un acide fort sur du phosphate naturel. Said phosphoric acid solution to be purified is preferably derived from the action of a strong acid on natural phosphate.
Les impuretés à éliminer de la solution sont donc essentiellement de nature minérale, les impuretés pouvant être métalliques ou non métalliques. The impurities to be removed from the solution are therefore essentially of a mineral nature, the impurities may be metallic or non-metallic.
De préférence, ledit au moins un polymère hydrosoiubie adsorbé présente une masse molaire comprise entre 100 et 40000 g/mol. Preferably, said at least one adsorbed hydrosubstituted polymer has a molar mass of between 100 and 40,000 g / mol.
La concentration de l'acide phosphorique dans la solution à purifier est avantageusement comprise entre 10 et 45% P205, de préférence entre 25¾t 30% P205. The concentration of the phosphoric acid in the solution to be purified is advantageously between 10 and 45% P 2 0 5 , preferably between 25 and 30% P 2 0 5 .
Selon une forme d'exécution préférée de l'invention, on met en œuvre, avant la première étape de filtration, une étape de traitement de la solution d'acide phosphorique pour en retirer les matières solides et organiques. According to a preferred embodiment of the invention, it is implemented, before the first filtration step, a step of treating the phosphoric acid solution to remove the solid and organic materials.
Ainsi, à l'issue dudit traitement, la solution d'acide phosphorique présente un taux de solide inférieur à 1%, de préférence inférieur ou égal à 0,7% et une teneur en carbone organique inférieure à 1000 ppm, de préférence inférieure ou égale à 300 ppm. Thus, at the end of said treatment, the phosphoric acid solution has a solids content of less than 1%, preferably less than or equal to 0.7% and an organic carbon content of less than 1000 ppm, preferably less than or equal to equal to 300 ppm.
Par ailleurs, le seuil de coupure de ladite membrane de nanofiltration est compris entre 150 et 1000 g. mol"1. Moreover, the cutoff threshold of said nanofiltration membrane is between 150 and 1000 g. mol "1 .
De préférence, la membrane de nanofiltration organique est une membrane en polyéthersulfone ou en polyamide/polysulfone, chargéë*positivement en milieu acide. De manière préférée, le polymère hydrosoluble est choisi parmi les polymères suivants : polyéthylinimine (PEI), acide polyacrylique (PAA), alcool polyvinylique (PVA) et polyvin4- pyridine (PV4P) Preferably, the organic nanofiltration membrane is a polyethersulfone or polyamide / polysulfone, positively charged in acidic medium *. Preferably, the water-soluble polymer is chosen from the following polymers: polyethylimine (PEI), polyacrylic acid (PAA), polyvinyl alcohol (PVA) and polyvinylpyridine (PV4P)
Un autre objet concerne une membrane de nanofiltration organique fonctionnalisée, notamment pour la purification d'une solution d'acide, phosphorique, comprenant une membrane de nanofiltration organique sur laquelle est adsorbé au moins un polymère hydrosoluble comprenant au moins une fonction aminé, une fonction aminé aromatique, une fonction acide et/ou une fonction alcool. Another subject relates to a functionalized organic nanofiltration membrane, especially for the purification of a phosphoric acid solution, comprising an organic nanofiltration membrane on which is adsorbed at least one water-soluble polymer comprising at least one amine function, an amine function aromatic, an acid function and / or an alcohol function.
De préférence, ledit au moins un polymère hydrosoluble adsorbé présente une masse molaire comprise entre 100 et 40000 g/mol. Preferably, said at least one adsorbed water-soluble polymer has a molar mass of between 100 and 40,000 g / mol.
Un autre objet de l'invention concerne un procédé de fabrication d'une membrane de nanofiltration organique fonctionnalisée, ledit procédé comprenant une étape d'adsorption, sur une membrane de nanofiltration organique, d'au moins un polymère hydrosoluble comprenant au moins une fonction aminé, une fonction aminé aromatique, une fonction acide et/ou une fonction alcool. Another subject of the invention relates to a process for producing a functionalized organic nanofiltration membrane, said process comprising an adsorption step, on an organic nanofiltration membrane, of at least one water-soluble polymer comprising at least one amine function , an aromatic amine function, an acid function and / or an alcohol function.
De manière préférée, ledit au moins un polymère hydrosoluble présente une masse molaire comprise entre 100 et 40000 g/mol. Preferably, said at least one water-soluble polymer has a molar mass of between 100 and 40,000 g / mol.
Selon un mode de réalisation préféré de l'invention, l'étape d'adsorption comprend la mise en contact de ladite membrane avec une solution dudit polymère hydrosoluble dans un acide fort. According to a preferred embodiment of the invention, the adsorption step comprises bringing said membrane into contact with a solution of said water-soluble polymer in a strong acid.
Ledit acide fort peut comprendre de l'acide chlorhydrique, de l'acide phosphorique, de l'acide nitrique et/ou de l'acide sulfurique. Said strong acid may comprise hydrochloric acid, phosphoric acid, nitric acid and / or sulfuric acid.
Par ailleurs, la concentration en polymère hydrosoluble dans ladite solution est avantageusement comprise entre 80 et 400 ppm, de préférence entre 100 et 300 ppm. Moreover, the concentration of water-soluble polymer in said solution is advantageously between 80 and 400 ppm, preferably between 100 and 300 ppm.
De préférence, l'étape d'adsorption est réalisée à une température comprise entre 25 et 100°C, de préférence entre 50 et 80°C, et sous une pîéssion absolue comprise entre 2 et 30 bar, de préférence entre 5 et 15 bar. Preferably, the adsorption step is carried out at a temperature of between 25 and 100 ° C., preferably between 50 and 80 ° C., and under an absolute pressure of between 2 and 30 bar, preferably between 5 and 15 bar. .
BREVE DESCRIPTION DES DESSINS D'autres caractéristiques et avantages de l'invention ressortiront de la description détaillée qui va suivre, en référence aux dessins annexés sur lesquels la figure 1 illustre de manière schématique un procédé de purification d'une solution d'acide phosphorique. BRIEF DESCRIPTION OF THE DRAWINGS Other features and advantages of the invention will emerge from the detailed description which follows, with reference to the accompanying drawings in which Figure 1 schematically illustrates a process for purifying a phosphoric acid solution.
DESCRIPTION DETAILLEE DE L'INVENTION DETAILED DESCRIPTION OF THE INVENTION
L'invention concerne un procédé de purification d'une solution d'acide phosphorique comprenant au moins une étape de filtration de l'acide phosphorique par une membrane de nanofiltration organique sur laquelle est adsorbé^au moins un polymère hydrosoluble comprenant au moins une fonction aminé, une fonction aminé aromatique, une fonction acide et/ou une fonction alcool. The invention relates to a purification method of a phosphoric acid solution comprising at least one filtration step of phosphoric acid with an organic nanofiltration membrane on which is adsorbed ^ at least one water-soluble polymer comprising at least one amine function , an aromatic amine function, an acid function and / or an alcohol function.
Pour cette étape de filtration, on fait circuler la solution d'acide phosphorique sur une membrane, de préférence de manière tangentielle à ladite membrane. Partant d'un volume VO de solution d'acide phosphorique brut, on recueille un perméat d'acide phosphorique purifié dont le volume est une fraction y VO du volume VO initial . Le coefficient VO est généralement compris entre 0,4 et 0,8, avantageusement compris entre 0,6 et 0,8. For this filtration step, the phosphoric acid solution is circulated over a membrane, preferably tangentially to said membrane. Starting from a volume VO of crude phosphoric acid solution, a permeate of purified phosphoric acid whose volume is a fraction y VO of the initial VO volume is collected. The coefficient VO is generally between 0.4 and 0.8, advantageously between 0.6 and 0.8.
Ladite membrane de nanofiltration organique sur laquelle est adsorbé un polymère hydrosoluble fonctionnalisé, également appelée « membrane fonctionnalisée » et son procédé d'obtention sont décrits en détail plus bas. Said organic nanofiltration membrane on which is adsorbed a functionalized water-soluble polymer, also called "functionalized membrane" and its method of obtaining are described in detail below.
De préférence, la concentration de l'acide phosphorique dans la solution est comprise entre 10 et 45% P205, de préférence entre 25 et 30% P205. Preferably, the concentration of the phosphoric acid in the solution is between 10 and 45% P 2 O 5, preferably between 25 and 30% P 2 O 5.
Le procédé selon l'invention peut être employé pour toute solution d'acide phosphorique, quelle que soit son origine. The process according to the invention can be used for any solution of phosphoric acid, whatever its origin.
L'acide phosphorique en solution est avantageusement de l'acide phosphorique dit « de voie humide » c'est-à-dire obtenu par l'action d'un^'acide fort, tel que l'acide chlorhydrique, l'acide nitrique et/ou l'acide sulfurique sur le phosphate naturel. L'acide phosphorique obtenu en solution est ensuite purifié selon l'invention. The phosphoric acid in solution is advantageously phosphoric acid called "wet" that is to say obtained by the action of a strong acid, such as hydrochloric acid, nitric acid and / or sulfuric acid on the natural phosphate. The phosphoric acid obtained in solution is then purified according to the invention.
La solution d'acide phosphorique obtenue par l'action de l'acide fort sur le phosphate naturel, également appelée « solution d'acide phosphorique brut », comprend généralement plusieurs impuretés métalliques. Selon une première étape optionnelle mais avantageuse, le procédé comprend une première étape de traitement de la solution d'acide phosphorique brut de manière à en retirer à la fois les matières solides et les matières organiques, qui seraient susceptibles de colmater de manière irréversible la membrane de nanofiltration employée par la suite. The phosphoric acid solution obtained by the action of the strong acid on the natural phosphate, also called "solution of crude phosphoric acid", generally comprises several metallic impurities. According to an optional but advantageous first step, the method comprises a first step of treating the crude phosphoric acid solution so as to remove both the solids and the organic materials, which could irreversibly clog the membrane. nanofiltration used later.
Ces étapes usuelles d'un procédé de préparation et de purification de l'acide phosphorique sont bien connues de l'homme du métier, et peuvent notamment inclure une clarification en vue d'obtenir une absorbance à 408 nm inférieure à 0,3 et une teneur réduite en particules solides. These usual steps of a process for the preparation and purification of phosphoric acid are well known to those skilled in the art, and may in particular include a clarification with a view to obtaining an absorbance at 408 nm less than 0.3 and a reduced content of solid particles.
A l'issue dudit traitement, la solution d'acide phosphorique qui sera ensuite purifiée selon l'invention présente une teneur en particules solides inférieure à 1%, de préférence inférieure ou égale à 0,7 %, et une teneur en carbone organique inférieure à 1000 ppm, de préférence inférieure ou égale à 300 ppm.  At the end of said treatment, the phosphoric acid solution which will then be purified according to the invention has a solid particles content of less than 1%, preferably less than or equal to 0.7%, and a lower organic carbon content. at 1000 ppm, preferably less than or equal to 300 ppm.
Grâce à ce traitement préalable, la durée f.deei ie et l'efficacité des membranes de nanofiltration utilisées pour la purification sont sensiblement améliorées. With this pretreatment, the duration f ei ie .de and effectiveness of nanofiltration membranes used for purification are significantly improved.
On soumet ensuite la solution d'acide phosphorique ainsi traitée à deux étapes successives de filtration par une membrane. The phosphoric acid solution thus treated is then subjected to two successive filtration steps by means of a membrane.
En référence à la figure 1, le procédé de purification d'une solution d'acide phosphorique comprend deux étapes successives de filtration par une„membrane. With reference to FIG. 1, the process for purifying a phosphoric acid solution comprises two successive stages of filtration by a membrane.
Selon une première étape de filtration, on fait circuler la solution d'acide phosphorique sur une membrane NF1 , de préférence de manière tangentielle à ladite membrane. According to a first filtration step, the phosphoric acid solution is circulated over an NF1 membrane, preferably tangentially to said membrane.
Partant d'un volume V0 de solution d'acide phosphorique brut, on recueille un premier perméat P1 d'acide phosphorique purifié dont le volume est une fraction y1 V0 du volume V0 initial. Starting from a volume V0 of crude phosphoric acid solution, a first permeate P1 of purified phosphoric acid whose volume is a fraction y1 V0 of the initial volume V0 is collected.
Le coefficient y1 est avantageusement compris entre 0,6 et 0,8. The coefficient y1 is advantageously between 0.6 and 0.8.
Selon une seconde étape de filtration, on fait circuler ledit premier perméat P1 sur une membrane NF2, de préférence de manière tangentielle à ladite membrane. According to a second filtration step, said first permeate P1 is circulated over an NF2 membrane, preferably tangentially to said membrane.
La membrane NF2 employée dans la deuxième étape peut être la même que la membrane NF1 employée dans la première étape où Bien être une membrane différente mais présentant une structure chimique similaire. On recueille ainsi un second perméat P2 d'acide phosphorique purifié dont le volume est une fraction y2 V0 du volume V0 initial. The NF2 membrane used in the second step may be the same as the NF1 membrane used in the first step where Well be a different membrane but having a similar chemical structure. A second permeate P2 of purified phosphoric acid whose volume is a fraction y2 V0 of the initial volume V0 is thus collected.
Le coefficient V0 est typiquement compris entre 0,4 et 0,8. The coefficient V0 is typically between 0.4 and 0.8.
Le second perméat P2 est caractérisé par une composition en impuretés métalliques inférieure à celle du premier perméat PL The second permeate P2 is characterized by a lower metal impurity composition than that of the first permeate PL
L'acide phosphorique purifié selon l'invention peut être valorisé, selon sa teneur, soit comme un acide alimentaire, soit comme le résultat d'une étape intermédiaire de purification, avant les traitements de finition (par exemple, une extraction liquide-liquide). The purified phosphoric acid according to the invention can be upgraded, depending on its content, either as a food acid or as the result of an intermediate purification step, before the finishing treatments (for example, a liquid-liquid extraction). .
L'invention concerne également une membrane de nanofiltration organique fonctionnalisée comprenant une membrane de nanofiltration organigue sur laquelle est adsorbé au moins un polymère hydrosoluble comprenant au moins une fonction aminé, une fonction aminé aromatique, une fonction acide et/ou une fonction alcool. The invention also relates to a functionalized organic nanofiltration membrane comprising an organic nanofiltration membrane on which is adsorbed at least one water-soluble polymer comprising at least one amine function, an aromatic amine function, an acid function and / or an alcohol function.
Ladite membrane est obtenue par modification d'une membrane de nanofiltration organique de type connu, dite membrane initiale. Said membrane is obtained by modifying an organic nanofiltration membrane of known type, called the initial membrane.
L'homme du métier connaît bien les membranes de nanofiltration suscpetibles d'être employées pour la nanofiltration de solutions. Those skilled in the art are well acquainted with nanofiltration membranes that can be used to nanofilter solutions.
Selon un mode avantageux de réalisation de l'invention, la membrane initiale est une membrane stable en milieu acide. According to an advantageous embodiment of the invention, the initial membrane is a stable membrane in an acid medium.
La membrane initiale présente un seuil de coupure adapté en fonction du degré de pureté que l'on souhaite atteindre. The initial membrane has a cut-off threshold adapted according to the degree of purity that it is desired to achieve.
De préférence, le seuil de coupure est de 150 g. mol"1, 300 g. mol"1, ou 1000 g. mol"1 ou toute valeur comprise entre 150 et 1000 g. mol"1. Preferably, the cutoff threshold is 150 g. mol "1 , 300 g mol -1 , or 1000 g. mol "1 or any value between 150 and 1000 g. mol " 1 .
Parmi les membranes appropriées, on citera à titre non limitatif les membranes organiques en poiyéthersuifone, polyamide/polysulfone ou autres, chargées positivement en milieu acide, en particulier les membranes commercialisées sous les marques MP, NF, Desal, ou PES respectivement par les sociétés Koch, Filmtec, Osmonics et Nadir. Suitable membranes include, but are not limited to, polyethylene / polysulfone or other positively charged organic polyethersulfone membranes, in particular the membranes marketed under the trademarks MP, NF, Desal, or PES respectively by the Koch companies. , Filmtec, Osmonics and Nadir.
La modification apportée à la membrane initiale comprend l'adsorption d'au moins un polymère hydrosoluble comprenant au moins une fonction aminé, une fonction aminé aromatique, une fonction acide et/ou une fonction alcool. Ledit au moins un polymère hydrosoluble peut être adsorbé seul ou en mélange, les différents polymères pouvant différer par la longueur de leur chaîne et/ou la fonction qu'ils portent. The modification made to the initial membrane comprises the adsorption of at least one water-soluble polymer comprising at least one amine function, an aromatic amine function, an acid function and / or an alcohol function. Said at least one water-soluble polymer may be adsorbed alone or as a mixture, the different polymers may differ in the length of their chain and / or the function they carry.
De préférence, ledit au moins un polymère hydrosoluble adsorbé présente une masse molaire comprise entre 100 et 40000 g/mol. Preferably, said at least one adsorbed water-soluble polymer has a molar mass of between 100 and 40,000 g / mol.
Les polymères hydrosolubles utilisés peuvent être linaires et/ou aromatiques et possèdent au moins une fonction aminé (primaire, secondaire ou tertiaire), une fonction acide, une fonction alcool, une fonction aminé aromatique ou autres. The water-soluble polymers used may be linear and / or aromatic and have at least one amine function (primary, secondary or tertiary), an acid function, an alcohol function, an aromatic amine function or the like.
De tels polymères hydrosolubles sont bién^connus de l'homme du métier, plus particulièrement les polymères suivants : Polystabil ®, Polyéthylinimine (PEI), disponible commercialement sous le nom PolyminP PIP, Acide polyacrylique (PAA), Alcool polyvinylique (PVA) et Polyvin4-pyridine (PV4P) peuvent être utilisés. Such water-soluble polymers are known to those skilled in the art, more particularly the following polymers: Polystabil®, Polyethylinimine (PEI), commercially available under the name PolyminP PIP, polyacrylic acid (PAA), polyvinyl alcohol (PVA) and Polyvin4 Pyridine (PV4P) can be used.
Pour mettre en œuvre l'adsorption du polymère, on met en contact la membrane initiale avec une solution dudit polymère hydrosoluble dans un,acide fort. To carry out the adsorption of the polymer, the initial membrane is brought into contact with a solution of said water-soluble polymer in a strong acid.
Un procédé usuel de mise en contact du polymère hydrosoluble en solution avec la membrane comprend la circulation de ladite solution au travers de la membrane de nanofiltration. A conventional method of contacting the water-soluble polymer in solution with the membrane comprises circulating said solution through the nanofiltration membrane.
Ledit acide fort comprend typiquement de l'acide chlorhydrique, de l'acide phosphorique, de l'acide nitrique et/ou de l'acide sulfurique. Said strong acid typically comprises hydrochloric acid, phosphoric acid, nitric acid and / or sulfuric acid.
Selon une forme d'exécution préférée de l'invention, l'acide fort est constitué d'acide chlorhydrique et/ou d'acide phosphorique. According to a preferred embodiment of the invention, the strong acid consists of hydrochloric acid and / or phosphoric acid.
La concentration en polymère hydrosoluble dans ladite solution est comprise entre 80 et 400 ppm, de préférence entre 100 et 300 ppm. The concentration of water-soluble polymer in said solution is between 80 and 400 ppm, preferably between 100 and 300 ppm.
La mise en contact de ladite solution avec la membrane initiale est réalisée à une température comprise entre 25 et 100°C, de préférence entre 50 et 80°C, et sous une pression absolue comprise entre 2 et 30 bar, de préférence entre 5 et 15 bar. The said solution is brought into contact with the initial membrane at a temperature of between 25 and 100 ° C., preferably between 50 and 80 ° C., and under an absolute pressure of between 2 and 30 bar, preferably between 5 and 15 bar.
La solution est filtrée par la membrane et l'on fait recirculer le perméat jusqu'à l'obtention de l'adsorption souhaitée. L'homme du métier saura déterminer le temps nécessaire jusqu'à l'obtention de l'adsorption souhaitée. La durée de cette mise en contact est avantageusement d'au moins 1 heure, plus avantageusement d'au moins 3 heures. The solution is filtered through the membrane and the permeate is recirculated until the desired adsorption is obtained. Those skilled in the art will be able to determine the necessary time until the desired adsorption is obtained. The duration of this contacting is advantageously at least 1 hour, more preferably at least 3 hours.
Après vidange du dispositif, on nettoie la membrane modifiée avec de l'eau distillée. After emptying the device, the modified membrane is cleaned with distilled water.
On mesure périodiquement la conductivité électrique de l'eau ayant servi au nettoyage et l'on arrête le nettoyage lorsque la conductivité de l'eau se stabilise. The electrical conductivity of the water used for cleaning is periodically measured and the cleaning is stopped when the conductivity of the water stabilizes.
L'adsorption de polymère sur la membrane sé tfaidûit par un abaissement de 24 à 80% de la perméabilité hydraulique de la membrane initiale. The adsorption of polymer on the membrane is reduced by a reduction of 24 to 80% in the hydraulic permeability of the initial membrane.
D'une manière générale, la membrane ainsi modifiée est stable à pH très acide et présente une durée de vie supérieure à 6 mois. In general, the membrane thus modified is stable at a very acidic pH and has a lifetime greater than 6 months.
Par ailleurs, cette membrane présente l'avantage de permettre la mise en œuvre du procédé de purification à basse température, c'est-à-dire dans une gamme comprise entre 25 et 40°C. Moreover, this membrane has the advantage of allowing the implementation of the purification process at low temperature, that is to say in a range between 25 and 40 ° C.
Le procédé de préparation de la membrane décrit ci-dessus permet donc d'améliorer significativement les performances des membranes de nanofiltration actuellement présentes sur le marché. The process for preparing the membrane described above thus makes it possible to significantly improve the performance of the nanofiltration membranes currently on the market.
D'autre part, outre les avantages économiques5^ la rentabilité occasionnés par la durée de vie allongée des membranes, le procédé de purification présente l'avantage de ne pas générer d'effluents secondaires (à l'exception des solutions de nettoyage des équipements) ; il ne présente donc pas de risque pour l'environnement. On the other hand, besides the economic benefits 5 ^ profitability caused by the longer life of the membranes, the purification process has the advantage of not generating secondary effluent (excluding cleaning solutions Equipment ); it does not pose a risk to the environment.
L'acide phosphorique purifié obtenu par ledit procédé correspond à différents grades et peut se prêter à différentes utilisations. The purified phosphoric acid obtained by said process corresponds to different grades and can be used for different purposes.
D'une part, il peut être utilisé dans un procédé d'extraction liquide-liquide. On the one hand, it can be used in a liquid-liquid extraction process.
L'avantage de l'acide utilisé est qu'il présente une faible concentration de molybdène, ce qui engendre la diminution de l'emploi de NaHS utilisé pour la désarséniation. The advantage of the acid used is that it has a low concentration of molybdenum, which causes the decrease in the use of NaHS used for the desarriage.
Par ailleurs, la qualité de cet acide permet d'éviter le bouchage et l'encrassement des circuits, des vannes, des conduites et des instruments'de mesure. Il en résulte que la durée de vie de ces derniers est augmentée tandis que la durée des arrêts pour nettoyage est diminuée. Enfin, la formation de dépôt dans l'acide de qualité marchande durant le stockage et le transport est éliminée. Moreover, the quality of this acid makes it possible to avoid clogging and clogging of the circuits, the valves, the pipes and the measuring instruments. As a result, the service life of the latter is increased while the duration of the shutdowns for cleaning is reduced. Finally, deposition formation in commercial grade acid during storage and transportation is eliminated.
L'acide phosphorique purifié peut également trouver application dans la production d'acide de qualité alimentaire. Purified phosphoric acid may also find application in the production of food grade acid.
En particulier, l'invention permet de produire dej'acjde phosphorique pur à 30% P205, ce qui évite d'avoir à diluer de l'acide phosphorique à 60% P205. In particular, the invention makes it possible to produce pure phosphoric acid at 30% P 2 O 5, which avoids having to dilute phosphoric acid to 60% P 2 O 5.
Exemple 1 : Comparaison du degré de pureté obtenu avec le procédé de purification selon l'invention et le procédé décrit dans le document US 5,945,000 Example 1 Comparison of the Degree of Purity Obtained with the Purification Process According to the Invention and the Process Described in US 5,945,000
A des fins de comparaison, on met en oeuvre le procédé de purification d'acide phosphorique 25-30% P205 décrit plus haut avec unef membrane selon l'invention et avec une membrane telle que décrite dans le brevet US 5,945,000. For purposes of comparison, it implements the phosphoric acid purification process 25-30% P205 described above with f a membrane according to the invention and with a membrane as described in U.S. Patent 5,945,000.
Il s'agit d'un procédé discontinu, par batch alimenté, c'est-à-dire que l'on purifie successivement des volumes distincts d'acide phosphorique brut. This is a batch process, batch fed, that is to say that is purified successively separate volumes of crude phosphoric acid.
Dans cet exemple, la membrane est une membrane de nanofiltration organique modifiée par l'adsorption d'un seul polymère hydrosoluble, qui^possède une chaîne de polymérisation longue et une fonction aminé. In this example, the membrane is an organic nanofiltration membrane modified by adsorption of a single water-soluble polymer which has a long polymerization ^ chain and an amine function.
La membrane initiale servant de base à cette modification présente un seuil de coupure de 1000 g.mol"1. The initial membrane serving as a basis for this modification has a cutoff threshold of 1000 g.mol -1 .
La perméabilité de l'acide phosphorique purifié à 40°C par la membrane modifiée est de 0,73 l/h/m2/bar. The permeability of the phosphoric acid purified at 40 ° C. by the modified membrane is 0.73 l / h / m 2 / bar.
A la différence d'une membrane de nanofiltration organique de type connu dont la durée de vie est inférieure à 125 jours, la membrane utilisée dans l'invention est stable pendant plus d'un an d'utilisation en continu. Unlike an organic nanofiltration membrane of known type whose lifetime is less than 125 days, the membrane used in the invention is stable for more than one year of continuous use.
Le tableau 1 présente les concentrations en impuretés métalliques et non métalliques obtenues dans l'acide phosphorique purifié. Table 1 shows the concentrations of metallic and non-metallic impurities obtained in the purified phosphoric acid.
Figure imgf000011_0001
Figure imgf000012_0001
Figure imgf000011_0001
Figure imgf000012_0001
Tableau 1  Table 1
Exemple 2 Example 2
Dans cet autre exemple, on met en œuvre un procédé de purification similaire à celui de l'exemple 1 , mais avec une membrane différente. In this other example, a purification process similar to that of Example 1 is used, but with a different membrane.
il En l'occurrence, la membrane est une membrane de nanofiltration organique modifiée par l'adsorption d'un mélange de deux polymères hydrosolubles, qui diffèrent par leur fonction et/ou la longueur de leur chaîne. he In this case, the membrane is an organic nanofiltration membrane modified by the adsorption of a mixture of two water-soluble polymers, which differ in their function and / or the length of their chain.
La membrane initiale servant de base à cette modification présente un seuil de coupure de 300 g. mol"1 et possède une peau active en polyamide / polysulfone. The initial membrane serving as a basis for this modification has a cutoff threshold of 300 g. mol "1 and has an active skin of polyamide / polysulfone.
La perméabilité de l'acide phosphorique purifié à 40°C par la membrane modifiée est de 0,23 l/h/m2/bar. The permeability of the phosphoric acid purified at 40 ° C. by the modified membrane is 0.23 l / h / m 2 / bar.
Le tableau 2 présente les concentrations en impuretés métalliques et non métalliques obtenues dans l'acide phosphorique purifié. Table 2 shows the concentrations of metallic and nonmetallic impurities obtained in the purified phosphoric acid.
Figure imgf000013_0001
Mn (ppm) 14 . 0,15
Figure imgf000013_0001
Mn (ppm) 14. 0.15
Mo (ppm) 4 0,17 Mo (ppm) 4 0.17
Na (%) 0,1 0,03 Na (%) 0.1 0.03
Ni (ppm) 49 0,29 Ni (ppm) 49 0.29
Pb (ppm) 1 Pb (ppm) 1
U (ppm) 110 1 ,6 U (ppm) 110 1, 6
V (ppm) 208 1 ,35 V (ppm) 208 1, 35
Zn (ppm) 285 3,49 Zn (ppm) 285 3.49
Si (%) 1,02 If (%) 1.02
Th (ppm) 5 0,04 Th (ppm) 5 0.04
Sr (ppm) 27 0 Sr (ppm) 27 0
Ti (ppm) 40 2,5 Ti (ppm) 40 2.5
Tm (ppm) 1 ,1 0,08 Tm (ppm) 1, 0.08
Y (ppm) 68 0,14 Y (ppm) 68 0.14
Yb (ppm) 4 0,02 Yb (ppm) 4 0.02
Nd (ppm) 4 0,14 Nd (ppm) 4 0.14
Zr (ppm) 83 1 ,29 Zr (ppm) 83 1, 29
Tableau 2 Table 2
Il va de soi que les exemples donnés plus haut ne le sont qu'à titre indicatif et nullement exhaustif. It goes without saying that the examples given above are only indicative and not exhaustive.
REFERENCES 1- US 5,945,000, "Methods of purifying phosphoric acid" REFERENCES 1- US 5,945,000, "Methods of purifying phosphoric acid"
2- M.P GONZALEZ, R. NAVARRO, I. SAUCEDO, M. AVILA, J. REVILLA, CH. BOUCHARD. « Purification of phosphoric acid solutions by reverse osmosis and nanofiltration » J. Desalination. 147, 315-320, (2002). 2- M. P. GONZALEZ, R. NAVARRO, I. SAUCEDO, M. AVILA, J. REVILLA, CH. BOUCHARD. "Purification of phosphoric acid solutions by reverse osmosis and nanofiltration" J. Desalination. 147, 315-320, (2002).
3- WO 01/89654 (OSMONICS), « Acid stable membranes for nanofiltration » 3- WO 01/89654 (OSMONICS), "Acid stable membranes for nanofiltration"

Claims

REVENDICATIONS
1 . Procédé de purification d'une solution d'acide phosphorique, comprenant une étape de filtration de l'acide phosphorique par une membrane de nanofiltration, caractérisé en ce que la membrane de nanofiltration est une membrane de nanofiltration organique sur laquelle est adsorbé au moins un polymère hydrosoluble comprenant au moins une fonction aminé, une fonction aminé aromatique, une fonction acide et/ou une fonction alcool. 1. Process for the purification of a phosphoric acid solution, comprising a step of filtration of phosphoric acid by a nanofiltration membrane, characterized in that the nanofiltration membrane is an organic nanofiltration membrane on which at least one polymer is adsorbed water-soluble composition comprising at least one amino function, an aromatic amine function, an acid function and / or an alcohol function.
2. Procédé selon la revendication 1 , caractérisé en ce que ledit au moins un polymère hydrosoluble adsorbé présente une masse molaire comprise entre 100 et 40000 g/mol. 2. Method according to claim 1, characterized in that said at least one adsorbed water-soluble polymer has a molar mass of between 100 and 40,000 g / mol.
3. Procédé selon l'une des revendications 1 ou 2, caractérisé en ce que la concentration de l'acide phosphorique dans la solution à purifier est comprise entre 10 et 45% P205, de préférence entre 25 et 30% P205. 3. Method according to one of claims 1 or 2, characterized in that the concentration of phosphoric acid in the solution to be purified is between 10 and 45% P205, preferably between 25 and 30% P205.
4. Procédé selon l'une des revendications 1 à 3, caractérisé en ce qu'il comprend, avant la première étape de filtration, une étape de traitement de la solution d'acide phosphorique pour en retirer les matières solides et organiques. 4. Method according to one of claims 1 to 3, characterized in that it comprises, before the first filtration step, a step of treating the phosphoric acid solution to remove the solid and organic materials.
5. Procédé selon la revendication 4, caractérisé en ce qu'à l'issue dudit traitement, la solution d'acide phosphorique présente un taux de solide inférieur à 1 %, de préférence inférieur ou égal à 0,7 %, et une teneur en carbone organique inférieure à 1000 ppm, de préférence inférieure ou égale à 300 ppm. 5. Method according to claim 4, characterized in that after said treatment, the phosphoric acid solution has a solids content of less than 1%, preferably less than or equal to 0.7%, and a content of organic carbon less than 1000 ppm, preferably less than or equal to 300 ppm.
6. Procédé selon l'une des revendications 1 à 5, caractérisé en ce que le seuil de coupure de ladite membrane est compris entre 150 et 1000 g.mol-1. 6. Method according to one of claims 1 to 5, characterized in that the cutoff threshold of said membrane is between 150 and 1000 gmol-1.
7. Procédé selon l'une des revendications 1 à 6, caractérisé en ce que la membrane de nanofiltration organique est une membrane en polyéthersulfone ou en polyamide/polysulfone, chargée positivement en milieu acide. 7. Method according to one of claims 1 to 6, characterized in that the organic nanofiltration membrane is a polyethersulfone or polyamide / polysulfone membrane, positively charged in an acidic medium.
8. Procédé selon l'une des revendications 1 à 7, caractérisé en ce que le polymère hydrosoluble est choisi parmi les polymères suivants : polyéthylinimine (PEI), acide polyacrylique (PAA), alcool polyvinylique (PVA) et polyvin4-pyridine (PV4P). 8. Method according to one of claims 1 to 7, characterized in that the water-soluble polymer is selected from the following polymers: polyethylinimine (PEI), polyacrylic acid (PAA), polyvinyl alcohol (PVA) and polyvin4-pyridine (PV4P) .
9. Procédé selon l'une des revendications 1 à 8, caractérisé en ce que la solution d'acide phosphorique à purifier est issue de l'action d'un acide fort sur du phosphate naturel.  9. Method according to one of claims 1 to 8, characterized in that the phosphoric acid solution to be purified is derived from the action of a strong acid on natural phosphate.
PCT/MA2013/000003 2012-03-06 2013-03-06 Process for purifying phosphoric acid by nanofiltration WO2013133684A1 (en)

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AU2013228080A AU2013228080B2 (en) 2012-03-06 2013-03-06 Process for purifying phosphoric acid by nanofiltration
CA2870066A CA2870066C (en) 2012-03-06 2013-03-06 Process for purifying phosphoric acid by nanofiltration
RU2014140320A RU2625872C2 (en) 2012-03-06 2013-03-06 Method of cleaning phosphoric acid by nanofiltration
ZA2014/07233A ZA201407233B (en) 2012-03-06 2014-10-06 Process for purifying phosphoric acid by nanofiltration

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FR1252031A FR2987830B1 (en) 2012-03-06 2012-03-06 PROCESS FOR THE PURIFICATION OF PHOSPHORIC ACID BY NANOFILTRATION
FR1252031 2012-03-06
US201261611141P 2012-03-15 2012-03-15
US61/611,141 2012-03-15

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GB2522244A (en) * 2014-01-20 2015-07-22 Bateman Advanced Technologies Ltd Method of purifying phosphoric acid
CN104828795A (en) * 2015-05-13 2015-08-12 南京工业大学 Wet phosphoric acid production process through ceramic membrane method
RU2574453C1 (en) * 2014-07-18 2016-02-10 Федеральное государственное бюджетное образовательное учреждение высшего профессионального образования "Кубанский государственный университет" (ФГБОУ ВПО "КубГУ") Method for obtaining composite anisotropic cation-exchange membrane
CN111591967A (en) * 2020-05-29 2020-08-28 盛隆资源再生（无锡）有限公司 Recovery processing method of phosphoric acid waste acid
EP3925689A1 (en) 2020-06-16 2021-12-22 Prayon Process for purifying a phosphate containing acidic solution comprising impurities and apparatus for applying same
FR3117103A1 (en) 2020-12-09 2022-06-10 Ocp Sa METHOD FOR DETERMINING MIXING PARAMETERS FOR THE PREPARATION OF A PHOSPHORIC ACID SOLUTION COMPRISING A CONTROLLED CONTENT OF ONE OR MORE OF ITS CONSTITUENTS
WO2023083958A1 (en) 2021-11-12 2023-05-19 Takhim For Technology And Business Services Process for the production of a purified phosphoric acid solution and/or dicalcium phosphate salts
WO2024025404A1 (en) 2022-07-25 2024-02-01 Universite Mohammed VI Polytechnique Method for obtaining uranium salts by nanofiltration

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Cited By (10)

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Publication number Priority date Publication date Assignee Title
GB2522244A (en) * 2014-01-20 2015-07-22 Bateman Advanced Technologies Ltd Method of purifying phosphoric acid
RU2574453C1 (en) * 2014-07-18 2016-02-10 Федеральное государственное бюджетное образовательное учреждение высшего профессионального образования "Кубанский государственный университет" (ФГБОУ ВПО "КубГУ") Method for obtaining composite anisotropic cation-exchange membrane
CN104828795A (en) * 2015-05-13 2015-08-12 南京工业大学 Wet phosphoric acid production process through ceramic membrane method
CN111591967A (en) * 2020-05-29 2020-08-28 盛隆资源再生（无锡）有限公司 Recovery processing method of phosphoric acid waste acid
EP3925689A1 (en) 2020-06-16 2021-12-22 Prayon Process for purifying a phosphate containing acidic solution comprising impurities and apparatus for applying same
WO2021254944A1 (en) 2020-06-16 2021-12-23 Prayon Process for purifying a phosphate containing acidic solution comprising impurities and apparatus for applying same
FR3117103A1 (en) 2020-12-09 2022-06-10 Ocp Sa METHOD FOR DETERMINING MIXING PARAMETERS FOR THE PREPARATION OF A PHOSPHORIC ACID SOLUTION COMPRISING A CONTROLLED CONTENT OF ONE OR MORE OF ITS CONSTITUENTS
WO2022124874A1 (en) 2020-12-09 2022-06-16 Universite Mohamed Vi Polytechnique Method for determining mixing parameters for the preparation of a phosphoric acid solution comprising a controlled content of one or more of its constituents
WO2023083958A1 (en) 2021-11-12 2023-05-19 Takhim For Technology And Business Services Process for the production of a purified phosphoric acid solution and/or dicalcium phosphate salts
WO2024025404A1 (en) 2022-07-25 2024-02-01 Universite Mohammed VI Polytechnique Method for obtaining uranium salts by nanofiltration

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FR2987830A1 (en) 2013-09-13
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CA2870066A1 (en) 2013-09-12

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