128results about "Crystallization by component evaporation" patented technology

According to the low-energy-consumption evaporating crystallizer, a single driving motor is adopted, a rotating shaft rod is used for simultaneously driving a scale scraping assembly arranged in an evaporating cylinder to conduct dynamic scale scraping and solution stirring, one end of the rotating shaft rod passes through a first transmission mechanism and a linkage shaft, and the other end of the rotating shaft rod is driven by a second transmission mechanism. A spiral separation assembly in the gas-liquid separation tank is driven by the direction conversion mechanism to rotate at a high speed so as to strengthen gas-liquid separation; and the other end of the discharging pipe drives a discharging assembly in the discharging pipe to rotate through a second transmission mechanism, so that discharging blockage prevention and negative-pressure deslagging are realized. Through a single power source, cooperative linkage of five functions of scale scraping, stirring, separation, blocking prevention and slag discharging is achieved, the structure is compact, the problems that traditional equipment is serious in scaling, poor in gas-liquid separation effect and prone to blockage during discharging are effectively solved, and meanwhile energy consumption of the equipment is remarkably reduced.

The invention relates to the technical field of ammonium dihydrogen phosphate preparation, and discloses a high-purity ammonium dihydrogen phosphate crystallization device and a method thereof.The high-purity ammonium dihydrogen phosphate crystallization device comprises a first-stage crystallization system, a first-stage centrifugal separation system, a second-stage crystallization system and a second-stage centrifugal separation system which are connected in series. The primary crystallization system comprises a crystal elimination heater, a crystal elimination mixer, a bag filter and a DTB flash cooling crystallizer which are connected in sequence, and is used for primarily purifying a concentrated solution; the primary centrifugal separation system is used for separating primary crystals; the second-stage crystallization system comprises a crystal dissolving tank, an OSLO cooling crystallizer and the like, and deep crystallization is carried out after the first-stage crystal is dissolved; the secondary centrifugal separation system is used for separating secondary crystals; through two-stage crystallization coupling, mother liquor graded circulation, a unique gradient washing process and active impurity control, efficient and continuous production of battery-grade ammonium dihydrogen phosphate with wet-process phosphoric acid as a raw material is realized, the product purity is high, the process flow is simplified, the cost is low, and the system operation is stable.

The invention discloses a use method of 2, 4-dihydroxybenzoic acid dissolving and recrystallizing equipment, the 2, 4-dihydroxybenzoic acid dissolving and recrystallizing equipment comprises a closed dissolving kettle, a crystallization kettle and a mother liquor storage tank, the closed dissolving kettle, a first separator, a first filtrate storage tank and the crystallization kettle are connected in sequence, and the mother liquor storage tank is connected with a second separator. A discharge port of the crystallization kettle is connected with a feed port of a second separator, a filtrate discharge port of the second separator is connected with a liquid inlet of a second filtrate storage tank, and a liquid outlet of the second filtrate storage tank is communicated with a liquid inlet of the mother liquid storage tank through a third pipeline; the second pipeline between the first separation column and the second pump body is communicated with a liquid outlet of the mother liquid storage tank through a fourth pipeline; the second pipeline between the second pump body and the fourth pipeline is communicated with one end of a backflow pipeline, and the other end of the backflow pipeline is communicated with the first pipeline. The 2, 4-dihydroxy benzoic acid dissolving and recrystallizing equipment disclosed by the invention can be used for preparing 2, 4-dihydroxy benzoic acid with the purity of 99.68%, and the content of metal ions is reduced to 0.15 ppm.

A liquid separation method (10) for separating mono ammonium phosphate ("MAP") (20) in aqueous solution, includes: • a receiving step in which a process liquid which comprises water and MAP is received; • a cooling step in which a controlled cooling process is applied to the process liquid to induce the crystallization (14) of MAP; • a separating step (16) in which the crystallised MAP is separated from the remaining process liquid.

A hybrid process and system for separating water from an inlet brine solution is disclosed. The hybrid process couples at least two different separation processes / systems. The inlet brine solution is fed into a first separation process, which produces a water distillate and a brine concentrate. The brine concentrate from the first separation process is then fed into the second separation process to further recover additional water. The excess heat from the second separation process is supplied to the first separation process.

The present disclosure provides a preparation system and a preparation method for xylitol crystals. In the preparation system, outlets of a first centrifuge are connected with an inlet of a hot air drying tank and an inlet of a primary mother liquor storage tank through pipelines, respectively. Outlets of a second centrifuge are connected with an inlet of a second fluidized bed dryer and an inlet of a secondary mother liquor storage tank through pipelines, respectively. An outlet of a dicrystalline sugar dissolution tank is connected with an inlet of a blending tank through a pipeline. An outlet of a tricrystalline sugar dissolution tank is connected with the inlet of the primary mother liquor storage tank. The blending tank is provided with an inlet for a raw material of xylitol hydrogenation solution. An output of an outlet of a first fluidized bed dryer is prepared xylitol crystals.

The invention discloses a crystallization device, a brine lithium extraction system and a process thereof, and relates to the technical field of lithium ion recovery, the crystallization device comprises a crystallizer body, a stirring mechanism and a first vibration element, the crystallizer body is internally used for accommodating slurry, a feeding part on the crystallizer body is used for introducing a sodium carbonate solution and brine, and a discharging part on the crystallizer body is used for discharging lithium carbonate crystal slurry; the stirring mechanism is used for stirring slurry in the crystallizer body; the first vibration element is arranged on the side wall of the crystallizer body and can apply mechanical vibration to the crystallizer body, on one hand, strong fluid disturbance can be generated in mixed feed liquid of brine and a sodium carbonate solution, and mixing and mass transfer between the brine and the sodium carbonate solution are enhanced; on the other hand, the concentration gradient between solid-liquid phases and the concentration gradient inside feed liquid can be destroyed, local supersaturation areas are avoided, the uniformity of crystal nucleation growth is improved, on the other hand, the physical adsorption force and chemical bonding between crystal nuclei and the inner wall of the crystallizer body can be destroyed, and the nucleation growth efficiency of crystals is improved.

A production system, production method and application of general-purpose high-purity chemicals are disclosed. The production system includes a raw material tank, and an adsorption system, a crystallizer, a first light-impurity removal tower, a first heavy-impurity removal tower, a second light-impurity removal tower, a motorized tower, a second heavy-impurity removal tower, a vapor permeation device, a membrane separation system and a filling system connected with the raw material tank in sequence. The high-purity chemicals produced by the above system have high purity and excellent quality. Compared with the prior art, the system and method designed by the present disclosure have more pertinence, integrity, progressiveness, energy-saving, precision, high safety coefficient and great industrial promotion value. And the products produced are of excellent quality, which can meet the standards applied to the manufacturing of integrated circuit electronic components and meet the high-end needs of the semiconductor industry market.

This invention provides a production process for manufacturing metallic magnesium and industrial silicon by decomposing serpentine using the hydrochloric acid method. [Solution] The present invention provides a method for processing serpentine ore as a raw material using a two-stage countercurrent hydrochloric acid leaching process. The wet process steps include storage and filtration of the slurry after ore dressing, two-stage hydrochloric acid leaching under atmospheric pressure, washing and filtration of the silicon slag after leaching, removal of iron and nickel precipitation from the leaching solution, separation, washing and filtration of the obtained iron hydroxide and nickel hydroxide, crystallization and evaporation of the magnesium chloride solution, and production of hydrochloric acid using the gas generated after the thermal decomposition of magnesium chloride. The present invention has developed a serpentine decomposition technology using hydrochloric acid, a metallic magnesium production process using a drying-electrolytic method, and a process for producing industrial silicon by smelting silicon slag in an electric furnace.

Provided is a method for separating impurities and cobalt without using an electrolysis process from a cobalt chloride solution containing impurities and producing a high purity cobalt sulfate. The production method includes: a first solvent extraction step (S1) of bringing an organic solvent containing an alkyl phosphoric acid-based extractant into contact with a cobalt chloride solution containing impurities, and extracting zinc, manganese, and calcium into the organic solvent to separate to remove zinc, manganese, and calcium; a copper removal step (S2) of adding a sulfurizing agent to a cobalt chloride solution and generating a precipitate of sulfide of copper to separate to remove copper; a second solvent extraction step (S3) of bringing an organic solvent containing a carboxylic acid-based extractant into contact with a cobalt chloride solution and back extracting cobalt with sulfuric acid after extracting cobalt into the organic solvent to obtain cobalt sulfate solution; and a crystallization step (S4) of the cobalt sulfate solution obtained after having undergone through the second solvent extraction step (S3). These steps are sequentially executed. Without using an electrolysis process, a high purity cobalt sulfate is directly produced by separating cobalt and impurities containing manganese.

A method for recycling nickel, cobalt and manganese from a feed liquid containing nickel, cobalt and manganese, the method comprising: (1) subjecting the feed liquid to a first extraction to obtain an aqueous phase 1 and an organic phase 1; (2) subjecting the aqueous phase 1 to a second extraction to obtain an organic phase 2 and an aqueous phase 2 having a pH value of 5-7.5; and (3) successively subjecting the organic phase 2 to washing and reverse extraction to obtain a solution containing nickel, cobalt and manganese, wherein an extractant A used in the second extraction comprises a carboxylic acid extractant.

The invention provides a ship tail gas integrated treatment device and method integrating a waste heat recovery function and multi-pollutant collaborative purification. The ship tail gas integrated treatment device comprises a pretreatment module, a waste heat recovery module, a collaborative oxidation module, an absorption purification module, a medicament circulation module and an intelligent control module which are integrated in a closed shell and sequentially communicate with one another. According to the invention, the core defects of poor collaboration, insufficient ship adaptability and high operation cost of the traditional technology are solved. According to the device, impurities are removed through the pretreatment module, the reaction working condition is optimized through the waste heat recovery module, the pollutant activity is improved through the cooperation of the oxidation module, efficient absorption is achieved through the absorption and purification module, the intelligent control module adapts to working condition fluctuation, and finally the dual purposes of emission reduction and energy conservation are achieved. A real ship test shows that the device is high in purification efficiency, stable in operation and good in economical efficiency, can be widely applied to tail gas treatment of various ships, and has remarkable environmental value, economic value and industrial popularization value.

The invention relates to the technical field of industrial high-salinity wastewater treatment and recycling, and discloses a sodium sulfate evaporative crystallization process for treating comprehensive wastewater of a steel mill, which comprises the following steps: S1, performing multi-effect evaporation concentration on sodium sulfate concentrated water generated by the comprehensive wastewater of the steel mill after pretreatment and membrane separation concentration, sodium sulfate concentrated crystal mush is obtained; s2, carrying out solid-liquid separation on the sodium sulfate concentrated crystal mush to obtain sodium sulfate crystals and mother liquor; part of the mother liquor returns to the system to participate in circular evaporation and concentration; and S3, monitoring the concentration of the mother liquor which is circularly evaporated in the step S2, and executing intermittent mother liquor discharge based on a performance attenuation signal of the evaporation system. Through a composite process route of multi-effect evaporative crystallization, freezing crystallization, advanced oxidation and membrane separation, comprehensive steel mill wastewater with complex components and high organic matter content is successfully treated, a high-quality anhydrous sodium sulfate product is produced, and zero discharge of wastewater and recovery of valuable resources are realized.

The application provides a high-salt water and superheated steam vacuum spray flash evaporation device, and belongs to the technical field of high-salt water treatment, which comprises a flash evaporation box body, a salt water spraying assembly, a steam spraying pipe, a mesh barrier assembly, a first driving assembly and a second driving assembly, the salt water spraying assembly extends from the top of the flash evaporation box body to the inside of the flash evaporation box body and is used for spraying high-salt water into the inside of the flash evaporation box body in a conical state, the steam spraying pipe extends from the bottom of the flash evaporation box body to the inside of the flash evaporation box body and is used for spraying high-temperature steam into the inside of the flash evaporation box body in a conical state, and the mesh barrier assembly is arranged in the inside of the flash evaporation box body and is used for shielding salt-containing crystalline particles that float with steam. Compared with the prior art, the embodiment of the application can effectively avoid that high-temperature steam carries a small amount of fine salt-containing crystalline particles out of the flash evaporation box body, avoids the loss of salt-containing crystalline particles, and improves the collection efficiency of salt-containing crystalline particles.

The invention discloses a high-concentration salt wastewater salt separation system and a crystalline salt purification method.The high-concentration salt wastewater salt separation system comprises an ACP purification unit and a crystallization unit, impurities in high-concentration salt wastewater can be removed by adding chemicals into a reaction tank and utilizing a first purifier for purification and impurity removal treatment, crystalline salt is separated out through circulating heating of an evaporation crystallizer, and the crystallization unit is connected with the ACP purification unit; and then separating by using a second purifier to obtain industrial-grade high-purity crystal salt, and purifying the crystallization mother liquor again through reflux continuous circulation to remove impurities, so that the quality of the crystal salt is further improved, and the purity of the separated crystal salt can be up to 98% or above. The method solves the problems that crystalline salt is low in purity, cannot meet industrial standards of industrial salt, is high in impurity salt yield and the like due to residual impurities such as silicon and organic matters in inlet water, realizes zero discharge of wastewater in the whole process, reduces the operation cost, protects the environment, improves the quality of the crystalline salt and turns waste into wealth.

The invention relates to a method for initiating the crystallization of a solute present in a solution (S) at a concentration that makes it metastable, comprising the application of one or more plasma pulses to the solution (S).

The invention discloses efficient crystallization equipment for p-hydroxyacetophenone, and belongs to the technical field of p-hydroxyacetophenone production, and the efficient crystallization equipment is technically characterized by comprising a supporting table, the equipment can flexibly switch medicament forms according to process parameters such as feed liquid concentration, temperature and stirring rate, when feed liquid is in a high-viscosity state, liquid medicaments are easier to uniformly mix, and the crystallization efficiency is improved. When a crystallization system needs to be stabilized for a long time, the solid medicament can prolong the action period, reduce the supplementing frequency, adapt to intermittent and continuous production processes, is small in dosage and high in stability, does not need to be additionally provided with a dissolving device, and reduces energy consumption; according to the present invention, the automatic control is achieved, the manual operation error is reduced, the continuous production process is formed through the arranged crystallization treatment mechanism, the previous process creates the high-quality condition for the subsequent process, and the advantages of easy agent selective addition and good crystallization effect are provided.

Systems and methods for preparing compound crystals of erythritol and high-intensity sweeteners are provided. The systems may comprise a fermentation liquid storage tank (1), a ceramic membrane filtration system (2), a nanofiltration system (3), a first evaporator (4), a first crystallization kettle (5), a first centrifuge (6), a sugar dissolution tank (7), a decolorization tank (8), an ion exchange column (9), a blending tank (10), a second evaporator (11), a second crystallization kettle (12), a second centrifuge (13), a hot-air drying tank (14), a fluidized drying bed (15), and a finished product tank (16) sequentially connected through pipelines. The systems may further comprise a high-intensity sweetener storage tank (17), a primary mother liquor tank (18), and a secondary mother liquor tank (19). The finished product tank (16) may store a prepared compound crystallization product of the erythritol and the high-intensity sweetener.

Compositions and methods are provided for producing crystalline forms of organic acids or salts or lactones thereof from an aqueous solution. More specifically, methods are provided for producing a crystalline form of a salt of mevalonic acid (also referred to as X-MVA) from an aqueous solution, comprising subjecting the aqueous solution comprising said X-MVA to a purification step to produce a purified solution and crystallizing said X-MVA from said purified solution by water solvent crystallization. Methods are also provided for producing mevalonolactone from an aqueous solution comprising X-MVA, comprising subjecting the aqueous solution comprising said X-MVA to cation exchange thereby converting said aqueous solution comprising X-MVA to an aqueous solution comprising mevalonolactone (MVL). Methods are also provided for producing mevalonolactone monohydrate crystals.

The present application relates to a kind of large particle size sodium nitrate multistage flash cooling crystallization production systems, it includes feed unit, evaporation unit, seed unit, flash crystallization unit, condensation unit, thickening unit, centrifugal drying unit and mother liquor reflux unit, seed unit includes material pump and seed tank, the discharge port of separator is connected to seed tank by material pump;Flash crystallization unit includes first flash crystallization ware, first material pump, second flash crystallization ware, second material pump, third flash crystallization ware and third material pump, the discharge port of seed tank is connected to the feed port of first flash crystallization ware, first flash crystallization ware, second flash crystallization ware, third flash crystallization ware are sequentially connected.The sodium nitrate solution of the present application is distributed uniformly by multistage flash, crystal growth time, and crystal size is adjusted by controlling fine crystal elimination amount, crystal size is large, particle size distribution is uniform, crystal size D90≥0.9mm, variation coefficient CV≤25.

The invention discloses an adipic acid crystallizer vacuum system and method capable of realizing zero liquid discharge of nitrogen-containing wastewater, which adopts a multi-stage Roots vacuum unit to realize pressure control on the adipic acid crystallizer vacuum system and a nitric acid concentration tower through a front buffer tank of the multi-stage Roots vacuum unit. Most condensable gas of the nitrite-containing steam generated by the adipic acid crystallizer is condensed and recovered to a condensate tank by using a gas condenser; uncondensed nitrogen-containing gas and a gas phase of the nitric acid concentration tower enter a buffer tank through pressure control, then are extruded by a multi-stage vacuum unit and are subjected to deep condensation treatment, condensed liquid enters a liquid storage tank through potential difference, and liquid in the liquid storage tank is sent to the nitric acid concentration tower through liquid level control to serve as reflux absorption liquid to absorb nitrite gas volatilized by the concentration tower; the adipic acid crystallizer vacuum system technology replaces a traditional steam injection pressurization vacuum system technology, consumption of medium-pressure steam and circulating water is reduced, zero liquid discharge of nitrogen-containing wastewater is achieved, and the adipic acid crystallizer vacuum system technology has remarkable environmental protection benefits and economic benefits.

The invention relates to a process for obtaining an amino acid in crystalline form, from a salt of said amino acid in aqueous solution, in the presence of carbon dioxide under pressure, said process being carried out in a forced circulation crystallizer (1), the latter comprising a chamber (2) having a lower part (3) and an upper part (4), the lower part (3) containing an aqueous liquid medium (6) comprising the amino acid and the upper part (4) containing carbon dioxide under pressure (7), and an external circuit (8) to this chamber (2) supplied with aqueous solution of said amino acid (5) and bringing it into the upper part (4) of the chamber (2), said external circuit (8) being connected to the chamber (2) from an outlet (9) located in the lower position of the chamber (2) to at least one inlet (10, 17) located in the upper position of the chamber (2), passing through a heat exchanger (11),said process comprising the following steps: the forced circulation crystallizer (1) is supplied with aqueous solution (5) of said salt, through at least one inlet (12, 12') in the external circuit (8) opening into the upper part (4) of the chamber (2) via the inlet (10); the aqueous solution (5) of said salt arriving in the upper part (4) of the chamber (2) from at least the inlet (10,17) by means of a distributor (13) emitting downward jets (14) towards the lower part (3) of the chamber (2); carbon dioxide is injected into the external circuit (8) and / or into the upper part (4) of the chamber (2) to obtain a pressurized carbon dioxide environment in the upper part (4) above the aqueous liquid medium (6); a juice containing the amino acid in crystalline form is collected at the bottom of the chamber (2) and conveyed to a purification module (15), and a juice substantially free of amino acid in crystalline form is drawn off and recirculated into the external circuit (8); and said amino acid is obtained in crystalline form in the purification module (15).

Improved Salt Crystal Production Unit. The present invention relates to a unit for producing salt crystals and fresh water from an initial aqueous solution containing an initial salt concentration. The unit comprises a desalination device adapted to receive said initial aqueous solution at one inlet and to discharge separately, at first and second outlets, an aqueous solution containing a salt concentration higher than the initial concentration, and an aqueous solution containing a salt concentration lower than the initial concentration. Figure for the abstract: None

Techniques according to the present disclosure include capturing carbon dioxide from a dilute gas source with a CO2 capture solution to form a carbonate-rich capture solution; separating at least a portion of carbonate from the carbonate-rich capture solution; forming an electrodialysis (ED) feed solution; flowing a water stream and the ED feed solution to a bipolar membrane electrodialysis (BPMED) unit; applying an electric potential to the BPMED unit to form at least two ED product streams including a first ED product stream including a hydroxide; and flowing the first ED product stream to use in the capturing the carbon dioxide from the dilute gas source with the CO2 capture solution.

The present technology relates to processes useful for making crystalline S)-1, 1-bis(4-fluorophenyl)propan-2-yl (3-acetoxy-4-methoxypicolinoyl)-Lalaninate Compound (I) comprising: distilling a mixture comprising: an aprotic organic solvent, a protic organic solvent, Compound (I) and seed Compound (I), or comprising: distilling a mixture comprising: an aprotic organic solvent and Compound (I), and crystallizing Compound (I) by creating a second mixture comprising: a protic organic solvent, Compound (I) and seed Compound (I). Processes disclosed herein describe more stable, storage compatible preparations of Compound (I). Also disclosed are preparations of Compound (I) which have fewer (trace) impurities.

A process for the formation of high-purity magnesium L-lactate crystals from homogenous and heterogenous decomposed organic waste is provided. The process provides magnesium L-lactate crystals with improved enantiomeric purity and overall purity which are particularly suitable for reuse in the production of new polylactic acid.

The invention discloses a method and a system for purifying ammonium sulfate. The method comprises the steps of raw material pretreatment, oxidation impurity removal, precipitation impurity removal, carbon material adsorption, crystallization drying and the like for synergic impurity removal. In the raw material pretreatment, insoluble impurities are removed by using a gradient dissolution method and organic filter membrane filtration; the oxidation impurity removal adopts hydrogen peroxide to oxidize low-valence metal ions under the conditions of specific temperature and pH; a composite precipitator composed of organic phosphonate and magnesium salt is used for precipitation and impurity removal; carbon material adsorption adopts activated carbon with a specific specific surface area to adsorb organic matters; and the crystallization and drying are performed by controlling the temperature to perform evaporation concentration, gradient cooling crystallization and drying. The system and the method can effectively solve the problems of incomplete impurity removal, high cost, complex process and environmental pollution in the existing ammonium sulfate purification technology, have the advantages of efficient impurity removal, economical efficiency optimization of the whole process and environmental friendliness, and realize synergistic removal of heavy metal ions, organic matters and colloidal particles.

The application discloses a crystallization recovery device and method for high-salinity wastewater. The crystallization recovery device for high-salinity wastewater comprises a liquid storage bottle, an absorbing member, a longitudinal absorbing part, a horizontal transporting part and a crystallization part. One end of the longitudinal absorbing part is inserted into the liquid storage bottle and can contact with the high-salinity wastewater therein. The other end of the longitudinal absorbing part is connected to the center of the horizontal transporting part. The crystallization part is annular and is connected to the bottom of the horizontal transporting part. A plurality of longitudinal and / or horizontal capillary tubes are arranged in the absorbing member, and each capillary tube in the absorbing member is in communication with each other. An evaporation plate is arranged on the top of the absorbing member. The evaporation plate is used for absorbing solar energy and conducting heat energy to the absorbing member. The application utilizes the capillary force to draw the high-salinity wastewater into the absorbing member, and utilizes the evaporation plate to convert the solar energy into heat energy, so that the high-salinity wastewater in the absorbing member is heated and crystallized, and the crystallization recovery treatment of the high-salinity wastewater is realized with reduced dependence on external energy.

Crystallizer devices and methods of direct air capture of carbon dioxide are described herein. The methods include providing one or more polymeric strands in contact with an alkaline capture solution. Each of the polymeric strands is comprised of a plurality of polymeric fibers that combine to form an outer surface of the polymeric strand. The outer surface of the strand forms a crystallizing surface. The alkaline capture solution travels by way of capillary force from the outer surface of the strand inwardly through intra-strand pores and from a first end of the strand in a direction towards a second end of the strand through intra-strand pores. The methods also include, as the alkaline solution travels towards the second end, contacting the one or more polymeric strands with ambient air such that KOH within the alkaline solution reacts with CO2 to form K2CO3 precipitate at the crystallizing surface.

To provide a method for producing bis-2-hydroxyethyl terephthalate (BHET), by which the crystal of the BHET having a high purity can stably be obtained from an aqueous solution of the BHET while reducing the capacity of an apparatus, a construction cost, an installation area, etc., compared with those of a conventional method and reducing the frequency of the dissolving operation of scaling.SOLUTION: Using a crystallization tank 10 for performing a crystallization operation of an aqueous solution containing 20 to 30wt% of BHET and a vacuum generation device 32 for reducing a pressure inside the crystallization tank 10, A step of adiabatically cooling the aqueous solution by adiabatically expanding the water vapor and lowering the temperature of the water vapor to obtain a slurry 13 containing BHET crystals in a crystallization vessel 10, and a step of supplying the slurry 13 extracted from the crystallization vessel 10 to a solid-liquid separator 20 to obtain BHET crystals and a mother liquid, wherein the slurry 13 is continuously obtained in the crystallization vessel 10 under conditions of 3.7 to 8. 6kPaA and 30 to 45 °C.SELECTED DRAWING: Figure 1