Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01D—SEPARATION
  • B01D9/00—Crystallisation
  • B01D9/0059—General arrangements of crystallisation plant, e.g. flow sheets
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01D—SEPARATION
  • B01D9/00—Crystallisation
  • B01D9/0018—Evaporation of components of the mixture to be separated
  • B01D9/0031—Evaporation of components of the mixture to be separated by heating
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01D—SEPARATION
  • B01D9/00—Crystallisation
  • B01D9/004—Fractional crystallisation; Fractionating or rectifying columns
• • C—CHEMISTRY; METALLURGY
  • C01—INORGANIC CHEMISTRY
  • C01D—COMPOUNDS OF ALKALI METALS, i.e. LITHIUM, SODIUM, POTASSIUM, RUBIDIUM, CAESIUM, OR FRANCIUM
  • C01D3/00—Halides of sodium, potassium or alkali metals in general
  • C01D3/14—Purification
  • C01D3/16—Purification by precipitation or adsorption
• • C—CHEMISTRY; METALLURGY
  • C01—INORGANIC CHEMISTRY
  • C01F—COMPOUNDS OF THE METALS BERYLLIUM, MAGNESIUM, ALUMINIUM, CALCIUM, STRONTIUM, BARIUM, RADIUM, THORIUM, OR OF THE RARE-EARTH METALS
  • C01F11/00—Compounds of calcium, strontium, or barium
  • C01F11/20—Halides
  • C01F11/24—Chlorides
  • C01F11/32—Purification
• • C—CHEMISTRY; METALLURGY
  • C01—INORGANIC CHEMISTRY
  • C01F—COMPOUNDS OF THE METALS BERYLLIUM, MAGNESIUM, ALUMINIUM, CALCIUM, STRONTIUM, BARIUM, RADIUM, THORIUM, OR OF THE RARE-EARTH METALS
  • C01F11/00—Compounds of calcium, strontium, or barium
  • C01F11/20—Halides
  • C01F11/34—Bromides
• • C—CHEMISTRY; METALLURGY
  • C01—INORGANIC CHEMISTRY
  • C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
  • C01P2004/00—Particle morphology
  • C01P2004/60—Particles characterised by their size
  • C01P2004/61—Micrometer sized, i.e. from 1-100 micrometer
• • C—CHEMISTRY; METALLURGY
  • C01—INORGANIC CHEMISTRY
  • C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
  • C01P2006/00—Physical properties of inorganic compounds
  • C01P2006/80—Compositional purity

Definitions

• TITLE PROCESS FOR SEPARATING SOLUBLE SALTS CONTAINED IN A RESIDUE CONTAINING AT LEAST THREE SALTS TECHNICAL FIELD OF THE INVENTION
• the present invention relates to a process for separating at least 3 soluble salts contained in a residue, typically sodium, potassium and calcium salts. More particularly, it relates to a process making it possible, starting from said residue, to obtain separately a solution of calcium chloride, crystals of sodium chloride and crystals of potassium chloride.
• the invention also relates to an installation suitable for carrying out the separation process according to the invention.
• REFI incineration flue gas purification residues are generally obtained by washing a smoke (in particular waste incineration smoke) containing gaseous HCl using basic compounds, such as calcium (lime) and / or sodium (soda or baking soda) salts.
• basic compounds such as calcium (lime) and / or sodium (soda or baking soda) salts.
• a smoke is produced with a level of gaseous HCl sufficiently reduced so that the smoke, possibly after a subsequent filtration step, can be discharged into the atmosphere, and a residue containing a salt of the type chloride (especially sodium chloride, potassium chloride or calcium chloride).
• incineration flue gas cleaning residues are different.
• Four main families of incineration flue gas purification residues are thus listed: Calcium REFIOM, sodium REFIOM, fly ash (or "Fly ashes” in English), and Residual Sodium Products.
• the residues from the purification of incineration fumes thus comprise a large proportion of chemical compounds (in particular calcium, sodium and potassium salts, mainly in the form of chlorides) which can be recycled, in particular for reuse in industrial processes.
• Processes are also known for simultaneously upgrading two salts.
• the process of FR 2 951 383 which makes it possible to separately isolate sodium chloride and potassium chloride in crystalline form, by placing implementation of two stages of selective crystallization.
• the process of FR 2 951 383 requires the use of a reactive aqueous solution, preferably rich in salts, for the preparation of the aqueous production solution (which will be subjected to the stages of selective crystallization), and the adjustment of the concentrations of sodium chloride and potassium chloride in the aqueous production solution by adding salts, in particular the crystallized salts obtained by the process.
• calcium salts are only used in this process as an agent for precipitating sulphates and other impurities. Thus, the calcium is not valorized in this process.
• the invention thus provides a process for separating at least 3 soluble salts starting from a brine comprising said salts, said process comprising the following crystallization steps: a) a first crystallization of said brine, giving a first concentrated solution F1 comprising a solution of calcium salt, and a solid S1 comprising a mixture of sodium and potassium salts, b) a second crystallization of the solid S1 previously solubilized, giving a solid S2 comprising a crystallized sodium salt, and a solution F2 comprising a mixture of potassium salts, c) a third crystallization of solution F2, giving a solid S3 comprising a crystallized potassium salt and mother liquors F3.
• the first crystallization comprises a first selective crystallization and / or the second crystallization comprises a second crystallization selective and / or the third crystallization comprises a third selective crystallization.
• the three crystallization steps include selective crystallization steps.
• steps a), b) and c) are implemented successively.
• step a) comprises a crystallization step at a temperature T1 and T1 is chosen such that it is the temperature at which the first crystals appear when the brine comprising the 3 soluble salts is heated.
• step a) comprises a step of crystallization at a temperature T1
• step b) comprises a step of crystallization at a temperature T2
• step c) comprises a step of crystallization at a temperature T3 , the temperatures T1, T2 and T3 being such that the temperature T1 is higher than the temperature T2 and the temperature T2 is higher than the temperature T3.
• the first crystallization step is carried out at a pressure P1 and the second crystallization step is carried out at a pressure P2, the pressure P1 and / or the pressure P2 preferably varying from 0.9 at 1.5 bars absolute.
• the first crystallization step is carried out at a temperature T1 and the second crystallization step is carried out at a temperature T2 and the third crystallization step is carried out at a temperature T3.
• the temperature T 1 is preferably chosen such that it is the temperature of the appearance of the first crystals when the initial brine is heated.
• Temperatures T1 and T2 are generally defined according to the salt concentration of the brine to be treated, in order to apply the boiling retardation.
• the boiling retardation in step a) ranges from 10 to 30 ° C and / or the boiling retardation in step b) ranges from 5 to 20 ° C.
• the boiling point of a given product comprising a solvent and solutes may be higher than the boiling point of the solvent, this temperature difference is called "retardation of the boil".
• the retardation of boiling is expressed in degrees Celsius.
• the temperature T1 varies from 112 to 125 ° C and / or the temperature T2 varies from 105 to 115 ° C.
• the operating temperature T3 is determined by the crystallization curve of the potassium chloride / sodium chloride mixture.
• the pressure P3 is generally adapted to obtain the temperature T3.
• the temperature T3 varies from 30 to 50 ° C.
• the concentration of salts is typically determined by conductivity, by methods well known to those skilled in the art.
• the ionic concentration can be followed by conductimetry. This monitoring makes it possible to follow the precipitation because as long as the precipitation is in progress, the concentration remains the same (at saturation), and the temperature also remains constant. It is also possible to follow the evolution of the precipitation by measuring the temperature which will vary when the precipitation is finished.
• the method is implemented continuously.
• the progress of the process is based on monitoring the Pressure / Temperature pairs of steps 1, 2 and 3.
• the invention thus relates to a process making it possible, from a residue comprising at least three salts, such as an industrial residue, and in particular a residue from the purification of incineration fumes (such as REFIOM), to selectively isolate :
• sodium salt in particular sodium chloride or sodium bromide
• potassium salt in particular potassium chloride or potassium bromide
• - a calcium salt in particular calcium chloride or calcium bromide.
• the method of the invention makes it possible not only to upgrade the elements sodium and potassium, but also calcium.
• Crystallization techniques in particular selective crystallization, such as evaporation-crystallization, are known to those skilled in the art, and implemented at the industrial level, in particular in the chemical, mining or other industries. However, only selective processes for the isolation of 2 salts initially as a mixture are known and used industrially to date.
• the process of the invention allows not only to separate these salts from each other, but also to separate them from impurities such as sulfates and heavy metals.
• the salts obtained have a purity greater than or equal to 95%, preferably 96%, more preferably 98%, and particularly preferably greater than or equal to 99%.
• the process according to the invention makes it possible to obtain a quality of salts meeting the acceptability thresholds defined in the specifications of industrial consumers of said salts.
• the separation process according to the invention allows joint recovery of at least three salts.
• the process of the invention has the advantage of being applicable to a wide variety of brines, the temperature and pressure parameters being able to be adapted according to the overall and relative concentrations of salt in the brines.
• the invention also relates to the salts which can be obtained by the process of the invention, in particular a concentrated aqueous solution of calcium chloride (CaCl2), a solid comprising crystallized sodium chloride (NaCl), and a solid comprising crystallized potassium chloride (KCl).
• a concentrated aqueous solution of calcium chloride (CaCl2) a solid comprising crystallized sodium chloride (NaCl)
• KCl crystallized potassium chloride
• the invention relates to an installation 1 for the separation of at least 3 soluble salts from a brine comprising said salts, said installation comprising:
• first evaporator-crystallizer 2 comprising an inlet pipe 3 for introducing the brine comprising at least three salts, a first outlet pipe 4 for recovering a concentrated solution F1 comprising a solution of calcium salt and a second outlet pipe 5 to recover a solid S1 comprising a mixture of sodium and potassium salts;
• a second evaporator-crystallizer 6 comprising an inlet pipe supplied by the second outlet pipe 5 of the first evaporator-crystallizer 2, a first outlet pipe 7 for recovering a solid S2 comprising a crystallized sodium salt and a second outlet pipe outlet 8 to recover a solution F2 comprising a mixture of potassium salts;
• a third evaporator-crystallizer 9 comprising an inlet pipe supplied by the second outlet pipe 8 of the second evaporator-crystallizer 6 and a first outlet pipe 10 for recovering a solid S3 comprising a crystallized potassium salt and a second outlet pipe exit 11 to recover mother liquors F3.
• FIG. 1 describes an installation according to one embodiment of the invention.
• FIG. 2 describes an installation according to another embodiment of the invention.
• the present invention relates to a process for separating at least 3 soluble salts, preferably 3 halides, starting from a brine comprising said salts, said process comprising the following crystallization steps: a) a first crystallization, preferably selective, of said brine, giving a first concentrated solution F1 comprising a solution of calcium salt, and a solid S1 comprising a mixture of sodium and potassium salts, b) a second crystallization, preferably selective, of the solid S1 previously solubilized, giving a solid S2 comprising a crystallized sodium salt, and a solution F2 comprising a mixture of potassium salts, c) a third crystallization, preferably selective, of the solution F2, giving a solid S3 comprising a crystallized potassium salt and mother liquors F3.
• a “salt” can be present either in soluble form or in solid form.
• a solid salt can be in crystalline or amorphous form.
• the expression "crystallized salt” will denote a solid salt, for example obtained after crystallization steps b) and c).
• a salt soluble in a medium under consideration is a salt dissolved at atmospheric pressure and at room temperature (approximately 25 ° C.) in said medium.
• the purity of the solid salt can be measured by methods well known to those skilled in the art, for example by X-ray diffraction or by elemental analysis.
• the analysis can be carried out by optical emission spectroscopy with plasma induced by high frequency according to standard NF EN ISO 11885 and when the salt is a halide, such as a chloride or a bromide.
• the analysis can be carried out by assaying the dissolved anions by liquid phase ion chromatography according to standard NF EN ISO 10304-1.
• the concentration of calcium salt in the calcium salt solution can be measured according to methods well known to those skilled in the art, for example by conductimetry.
• the calcium salt purity of the calcium salt solution denotes the amount of calcium salt, expressed relative to the weight of dry matter of the calcium salt solution.
• the brine comprising at least 3 soluble salts is an aqueous solution in which said at least 3 soluble salts are dissolved.
• the brine comprising at least 3 soluble salts comprises at least three soluble halides, preferably the brine comprises at least one calcium salt, at least one sodium salt and at least one potassium salt.
• the brine comprises at least calcium chloride, sodium chloride and potassium chloride.
• the brine can however also include impurities. These can be sulfate salts, carbonate salts and hydroxide salts. They can also be metal salts, and in particular heavy metals.
• the total amount of impurities in the initial brine used in step a) of the process of the invention is typically less than or equal to 5% by weight, preferably less than or equal to 2% by weight, more preferably less than or equal to 1% by weight, relative to the total weight of the brine.
• the amount of impurities can be determined by measuring the concentration of unwanted salts by conductimetry or by elemental analysis according to methods well known to those skilled in the art.
• the overall concentration of the 3 salts in the brine used in step a) of the process of the invention is preferably greater than or equal to 200 g / L, and less than or equal 300 g / L. If the overall concentration of the 3 desired salts is greater than 300 g / L, the salts tend to precipitate spontaneously, which can hamper process control and selectivity.
• the brine used in step a) of the process of the invention advantageously has the following contents:
• the pH of the initial brine used in step a) of the process of the invention is between 8 and 10, preferably between 9 and 9.5.
• the method according to the invention may comprise, according to one embodiment, a preliminary step of preparing the brine comprising at least 3 salts, before step a) of the invention.
• the initial brine is obtained by dissolving one or more residues from the purification of incineration fumes, such as REFIOMs in an aqueous solution, typically pure water or a saline solution.
• the liquid / solid mass ratio in the initial brine used in step a) of the process of the invention ranges from 1 to 3, preferably from 2 to 2.5. This ratio will typically correspond to a water / incineration flue gas purification residue ratio.
• the brine used in the process of the invention can thus be obtained by mixing and dissolving one or more residues from the purification of incineration fumes chosen from a sodium REFIOM, a calcium REFIOM and fly ash.
• the proportions of each residue from the purification of incineration fumes can be adapted as a function of the salts desired at the end of the separation process.
• the step of solubilizing incineration flue gas purification residues is followed by filtration, typically by filter press, in order to separate the filtrate comprising the desired dissolved salts from the undesirable impurities having a size greater than or equal to 5 ⁇ m, preferably greater than or equal to 10 ⁇ m, which are then retained in the filter cake in the case of a filter press.
• the filtrate can be called crude brine.
• the raw brine is then treated to precipitate heavy metals, for example by acidification, typically by hydrochloric acid in order to lower the pH or by iron chlorides in order to precipitate fine elements such as than metal hydroxides.
• the pH can thus be lowered to be in the range going from 8 to 10, or even from 9 to 9.5.
• the treated filtrate can optionally be decanted and filtered, for example on sand and activated carbon, in order to separate the filtrate comprising the desired dissolved salts from the undesirable impurities having a size greater than or equal to 5 ⁇ m, preferably greater than or equal to at 10 pm.
• the initial brine can for example be obtained according to the process described in document WO 93/04983.
• Part of the raw brine (before possible treatment) can advantageously be recycled in the device allowing the mixing and solubilization of one or more residues from the purification of incineration fumes, such as REFIOM.
• crystallization techniques in particular selective crystallization, are known to those skilled in the art, and implemented at the industrial level, in particular in the chemical, mining or other industries.
• the crystallization steps implemented in the separation process according to the invention are evaporation-crystallization steps.
• Evaporation-crystallization comprises in particular a step of concentrating a salt solution by evaporation of water concomitant with a step of crystallizing a salt or a mixture of salts from the solution.
• precipitation / crystallization is concomitant with evaporation, this phenomenon is due to the fact that the concentration corresponding to the solubility limit of said solid is reached.
• precipitation / crystallization follows evaporation, said precipitation / crystallization generally results from cooling of the solution.
• these two phenomena can be combined, by collecting on the one hand the solid which precipitates when hot, then by cooling the mother liquors, from which the solid again precipitates. The two solid fractions can then be combined at the end of these two phenomena.
• Evaporation-crystallization also eliminates any liquid waste, producing very high quality water for new uses.
• the temperatures T1, T2 and T3 are different from each other. More particularly, according to one embodiment T3 is less than T2, which is itself less than T1 (T1> T2> T3).
• Step a) of the process of the invention typically comprises an evaporation-crystallization step which leads to the precipitation of a solid, which is a mixture of sodium and potassium salts. Said mixture of sodium and potassium salts generally has a pasty appearance.
• the process of the invention thus comprises a step in which the sodium salts and the potassium salts are precipitated / crystallized together.
• step a) can comprise a filtration step making it possible to separate the solid S1 and the concentrated solution F1.
• this filtration step makes it possible to separate the particles having a size greater than or equal to 100 ⁇ m.
• the solid S1 will have particle sizes of at least 100 ⁇ m, typically particle sizes ranging from 100 to 500 ⁇ m, preferably from 250 to 300 ⁇ m.
• the temperature T1 during the crystallization step is advantageously between 100 ° C and 130 ° C, preferably between 115 ° C and 125 ° C, in particular equal to approximately 120 ° C. These temperatures are typically suitable when the crystallization step is carried out at atmospheric pressure.
• the concentrated solution F1 comprising a calcium salt is preferably cooled, typically to a temperature of between 5 ° C and 55 ° C, in particular between 25 ° C and 45 ° C, for example at 35 ° C. It is then preferably filtered, for example by vacuum filtration, to remove any solid impurities. This gives an F'1 filtrate which can be marketed as it is.
• the calcium concentration of the filtrate F′1 is advantageously between 5% and 50% by weight, in particular between 20% and 40% by weight, for example 37% by weight.
• the solid S1 is washed with water.
• the quantity of water used for this washing is preferably minimal in order to limit the re-solubilization of the solid mixture and to limit the yield losses of step a).
• the washing water for the solid S1 is preferably recycled for the implementation of step a) of the method of the invention or at a step upstream thereof, for example for the formation of the initial brine.
• step a) comprises two sub-steps: a1) crystallization, preferably selective, of said brine at a temperature T1 and at a pressure P1, giving a first suspension L1, and water vapor, the water vapor being recovered after condensation in the form of condensed water, a2) filtration of the suspension L1, resulting in the concentrated solution F1 comprising a calcium salt, and a solid S1 comprising a mixture of salts sodium and potassium.
• the filtration step a2) makes it possible to separate the particles having a size greater than or equal to 100 ⁇ m.
• the solid S1 will have particle sizes of at least 100 ⁇ m, typically particle sizes ranging from 100 to 500 ⁇ m, preferably from 250 to 300 ⁇ m.
• the temperature T1 is advantageously between 100 ° C and 130 ° C, preferably between 115 ° C and 125 ° C, in particular equal to approximately 120 ° C.
• the solid S1 is preferably solubilized beforehand in step b) using the condensed water obtained in step a1).
• the solubilization of the solid S1 is carried out at a temperature between 60 ° C and 95 ° C, preferably between 75 ° C and 85 ° C, preferably at 80 ° C.
• the calcium, sodium and potassium salts are respectively calcium chloride, sodium chloride and potassium chloride.
• Step a) removes almost all of the calcium salts.
• the solid S1 typically comprises less than 1% by weight of calcium salts, and in particular of calcium chloride.
• the prior solubilization of the solid S1 is carried out with an aqueous solution, in particular the condensates obtained during the evaporation phase of step a), at a temperature between 60 ° C and 95 ° C, preferably between 75 ° C and 85 ° C, preferably at 80 ° C.
• the amount of solubilization water advantageously corresponds to that strictly necessary to reach the solubility limit of the mixed salts, which makes it possible to limit the amounts of water involved.
• the process of the invention does not include a step of introducing calcium chloride to the solid S1 obtained at the end of step a), before or after its solubilization.
• the remainder of steps b) and c) then corresponds to a process for the selective crystallization of a brine comprising a sodium salt and a potassium salt, in particular a mixture of sodium chloride and potassium.
• a brine comprising a sodium salt and a potassium salt, in particular a mixture of sodium chloride and potassium.
• T2 is advantageously between 105 ° C and 115 ° C, preferably equal to approximately 111 ° C.
• Step b) results in a solid S2 mainly comprising a crystallized sodium salt, and a solution F2 composed mainly of potassium salts and in particular of potassium chloride.
• step b) can comprise a filtration step making it possible to separate the solid S2 and the solution F2, the filtration then being vacuum filtration.
• this filtration step makes it possible to separate the particles having a size greater than or equal to 100 ⁇ m.
• the solid S2 will have particle sizes of at least 100 ⁇ m, typically particle sizes ranging from 100 to 500 ⁇ m, preferably from 250 to 300 ⁇ m.
• the solid S2 is washed with water.
• the amount of water used for this washing is advantageously minimal in order to limit the re-solubilization of the sodium salt and to limit the yield losses of step b).
• the water for washing the solid S2 is preferably recycled for the formation of the solid S2.
• the solid S2 is generally drained after washing.
• a crumbling step can also be implemented prior to the drying step, to facilitate this last step.
• the purity of the solution F2 is generally of the order of 70-90% by mass, typically about 80% by mass, in potassium salts, in particular potassium chloride.
• the purity is defined as being the quantity by mass of potassium salts, expressed relative to the weight of dry matter of the solution F2.
• the temperature T3 is generally chosen as a function of the crystallization point of the potassium salts, in particular of potassium chloride at the concentrations obtained. It will therefore be necessary to measure the concentration of potassium salt in solution F2 at the end of step b), in particular in potassium chloride, and to refer to the charts to determine the point of crystallization, which will then be the temperature.
• T3 is advantageously between 30 ° C and 50 ° C, preferably between 35 ° C and 45 ° C, for example equal to approximately 40 ° C.
• step c) can comprise a filtration step making it possible to separate the solid S3 and the mother liquors F3, the filtration then being able to be vacuum filtration.
• this filtration step makes it possible to separate the particles having a size greater than or equal to 100 ⁇ m.
• the solid S3 will have particle sizes of at least 100 ⁇ m, typically particle sizes ranging from 100 to 500 ⁇ m, preferably from 250 to 300 ⁇ m.
• the solid S3 is washed with water.
• the amount of water used for this washing is advantageously minimal in order to limit the re-solubilization of the potassium salt and to limit the yield losses of step c).
• the water for washing the solid S3 is preferably recycled for the formation of the solid S3.
• the solid S3 is generally wrung out after washing.
• a crumbling step can also be implemented prior to the drying step, to facilitate this last step.
• the mother liquors F3 are recycled at the top of step b).
• the mother liquors F3 can typically comprise potassium salts and sodium salts, typically potassium chlorides and sodium chlorides, not crystallized / precipitated during steps b) and c), in respective proportions for example of 80- 90% by weight of potassium salts and 10-20% by weight of sodium salts.
• the sodium, potassium and calcium salts obtained by the process are chlorides.
• the invention relates to an aqueous solution of calcium chloride obtainable by the process of the invention with a mass concentration ranging from 30 to 45%, advantageously about 38%, with a purity greater than or equal to 95%, in particular greater than or equal to 96%, for example equal to 97%. Purity is defined as being the quantity by mass of calcium chloride expressed relative to the total weight of dry matter.
• the invention also relates to a solid comprising crystallized sodium chloride obtainable by the process of the invention, said solid having a sodium chloride content greater than or equal to 97%, preferably greater than or equal to 98%. , in particular greater than or equal to 99%.
• the invention finally relates to a solid comprising crystalline potassium chloride obtainable by the process of the invention, said solid having a content of Potassium chloride greater than or equal to 97%, preferably greater than or equal to 98%, in particular greater than or equal to 99%.
• the installation 1 according to the invention comprises:
• first evaporator-crystallizer 2 comprising an inlet pipe 3 for introducing the brine comprising at least three salts, a first outlet pipe 4 for recovering a concentrated solution F1 comprising a solution of calcium salt and a second outlet pipe 5 to recover a solid S1 comprising a mixture of sodium and potassium salts;
• a second evaporator-crystallizer 6 comprising an inlet pipe supplied by the second outlet pipe 5 of the first evaporator-crystallizer 2, a first outlet pipe 7 for recovering a solid S2 comprising a crystallized sodium salt and a second outlet pipe outlet 8 to recover a solution F2 comprising a mixture of potassium salts;
• a third evaporator-crystallizer 9 comprising an inlet pipe supplied by the second outlet pipe 8 of the second evaporator-crystallizer 6 and an outlet pipe 10 for recovering a solid S3 comprising a crystallized potassium salt and a second outlet pipe 11 to recover mother liquor F3.
• Fig. 1 shows an embodiment of the installation according to the invention.
• the installation according to the invention is typically suitable for implementing the separation process according to the present invention.
• the installation ultimately makes it possible to jointly valorize at least three salts.
• the second evaporator-crystallizer 6 comprises an inlet pipe for introducing the solubilization liquid.
• the liquid for the solubilization can be obtained from the condensates obtained during the evaporation phase implemented in the first evaporator-crystallizer 2.
• the first evaporator-crystallizer 2 comprises an evaporator 2 "and a filter device 2", such as a filter press.
• the filtration device typically comprises the first outlet pipe 4 for recovering a concentrated solution F1 and the second outlet pipe 5 for recovering a solid S1.
• the evaporation device 2 ′ comprises a water vapor outlet pipe 13 capable of supplying the second evaporator-crystallizer.
• the installation further comprises one or more treatment devices supplied by the first outlet pipe 4.
• the second evaporator-crystallizer 6 comprises a hot solubilization device 6 "and a filtration device 6".
• the filtration device typically comprises the first outlet pipe 7 for recovering a solid S2 and the second outlet pipe 8 for recovering a solution F2.
• the evaporation device 2 ’ comprises a vapor outlet pipe (water vapor) 13, which after condensation produces condensate feeding the hot solubilization device 6’.
• the evaporation device 9 ′ also comprises a vapor outlet pipe (water vapor) 15, which after condensation produces condensates feeding the hot solubilization device 6 ’.
• the evaporation device 6 ′ also comprises a loop for recirculating all of the vapor condensates (water vapor), produced in the evaporators 2 ′, 6 ′ and 9 ′, feeding the solubilization device back to hot 6 ′ via line 16.
• Device 6 advantageously comprises a pipe, not shown, allowing excess water to be evacuated, preferably in order to recirculate it in a device for treating REFIs.
• the installation further comprises one or more treatment devices supplied by the first outlet pipe 7, said treatment devices being preferably chosen from a wiping device, a device. crumbling and a drying device, and their combination.
• the third evaporator-crystallizer 9 comprises a cooling device 9 "and a filtration device 9".
• the filtration device typically comprises the outlet pipe 10 for recovering a solid S3 and the third outlet pipe 11 for recovering the mother liquors F3.
• the outlet pipe 11 feeds the hot solubilization device 6 ', via the pipe 14.
• all or part of the mother liquors F3 can be recycled at the top of the evaporator-crystallizer 6, preferably all of the water. mothers F3 is recycled.
• the installation further comprises one or more treatment devices supplied by the first outlet pipe 10, said treatment devices being preferably chosen from among a wringing device, a crumbling device and a drying device, and their combination.
• the installation further comprises sensors for measuring the temperature and pressure in one or more of the evaporator-crystallizers (2, 6, 9).
• the installation further comprises a storage tank, upstream of the first evaporator-crystallizer 2, in order to supply the evaporator-crystallizer with brine via the inlet pipe 3.
• the installation comprises upstream of the first evaporator-crystallizer, a brine preparation device comprising at least 3 soluble salts.
• the device for preparing the brine comprises:
• At least one mixer / dissolver supplied by one or more inlet pipes for waste (s) from incineration fume purification and comprising an outlet pipe, and
• At least one filtration device such as a filter press, supplied by the outlet pipe of the mixer / dissolver, and comprising an outlet pipe comprising the filtrate,
• a settling and filtration device supplied by the outlet pipe comprising the filtrate, said filtrate having optionally been treated with reagents.
• the solubilization is carried out at room temperature.
• the pulp thus prepared is filtered in order to separate the filtrate composed of dissolved salts (10 ⁇ m filter press mesh) as a mixture of the undesirable impurities retained in the filter cake.
• the filter cake Before disposal in a storage center for hazardous waste, the filter cake is washed with water so as to recover some of the remaining salts.
• This washing operation has the dual objective of reducing the soluble fraction of the washing cake before disposal in a hazardous waste repository and of providing pre-salted water for dissolving the REFIOMs.
• the adjustment to 150 g per liter is obtained by recirculating a portion of the filtrate (raw brine).
• the temperature T1 was determined by heating the brine and determining the temperature at which the first crystals appeared, this is the temperature T 1.
• the brine thus prepared was introduced into an evaporator No. 1 at a temperature T1 of approximately 120 ° C. and at atmospheric pressure in order to obtain, on the one hand, a precipitation of the NaCl and KCl salts (solution S1) and on the other hand. starts with a solution F1 comprising CaCl2.
• the evaporation step is typically continued as long as the temperature T 1 remains constant, this means that crystallization is in progress.
• Solution F1 is cooled to 20 ° C and filtered, in order to obtain a filtrate comprising 37% concentrated CaCl2 (ready to be marketed).
• the precipitated NaCl and KCl salts are re-solubilized while hot with the condensed vapors from evaporator No. 1.
• the solubilized solution of NaCl and KCl salts will typically comprise on the order of 28.4% by weight of NaCl + KCl salts and on the order of 71.6% water, relative to the total weight of the solubilized solution.
• the concentration of NaCl and KCl salts is measured by the boiling retardation. Crystallization is followed by measuring the concentration of NaCl and KCl salts. Indeed, as long as the salt concentration remains constant, precipitation / crystallization is in progress.
• the temperature T2 is around 112 ° C.
• Evaporator n ° 2 made up of several zones, makes it possible to separate the 2 salts by difference in physical state, soluble and crystals.
• the NaCl crystals are refined by draining, crumbling and drying to a purity greater than 99%.
• the soluble part of the salts from evaporator n ° 2 is directed to evaporator n ° 3, the role of which is to cool the solution in order to reach the point of crystallization of KCI, that is to say the temperature. T3.
• the KCI crystals are refined by draining, crumbling and drying to a purity greater than 98%.
• the filtrates are recirculated at the top of the corresponding phase.
• the process according to the invention thus makes it possible to jointly upgrade 3 salts.

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• Organic Low-Molecular-Weight Compounds And Preparation Thereof (AREA)
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• 2020
  • 2020-01-08 FR FR2000119A patent/FR3105930B1/fr active Active
  • 2020-04-08 EP EP20718299.9A patent/EP4087670A1/de active Pending
  • 2020-04-08 CN CN202080096807.3A patent/CN115151322A/zh active Pending
  • 2020-04-08 WO PCT/EP2020/060103 patent/WO2021139902A1/fr not_active Ceased
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