PROCESS OF RECOVERING 3-HYDROXYPROPIONIC ACID AND SLURRY COMPOSITION COMPRISING 3-HYDROXYPROPIONIC ACID

Abstract

The present invention relates to a process of recovering 3-hydroxypropionic acid, comprising: forming a 3-hydroxypropionate crystal in a concentrate containing 3-hydroxypropionic acid in the presence of an alkali metal salt, preparing a solution containing 3-hydroxypropionate crystal separated from the concentrate, stirring an acid and the solution containing 3-hydroxypropionate crystal to form a precipitate, and subjecting the precipitate to a first washing, and a slurry composition comprising a precipitate prepared in the process of recovering 3-hydroxypropionic acid and 3-hydroxypropionic acid.

Claims

1. A process of recovering 3-hydroxypropionic acid, comprising: forming a 3-hydroxypropionate crystal in a concentrate containing 3-hydroxypropionic acid in the presence of an alkali metal salt; preparing a solution containing 3-hydroxypropionate crystal separated from the concentrate; stirring an acid and the solution containing 3-hydroxypropionate crystal to form a precipitate; and first washing the precipitate using a first washing liquid.

2. The process of recovering 3-hydroxypropionic acid according to claim 1, further comprising reusing the first washing liquid used in the first washing of the precipitate.

3. The process of recovering 3-hydroxypropionic acid according to claim 1, further comprising adding the acid to the solution containing 3-hydroxypropionate crystal at a temperature of 30? C. or more and 90? C. or less before the stirring of the acid and the solution containing 3-hydroxypropionate crystal to form a precipitate.

4. The process of recovering 3-hydroxypropionic acid according to claim 1, further comprising charging the acid and the solution containing 3-hydroxypropionate crystal into a reactor, either continuously or in 2 or more installments before the stirring of the acid and the solution containing 3-hydroxypropionate crystal to form a precipitate.

5. The process of recovering 3-hydroxypropionic acid according to claim 4, wherein: the solution containing 3-hydroxypropionate crystal is continuously charged into the reactor.

6. The process of recovering 3-hydroxypropionic acid according to claim 4, wherein: the acid is charged into the reactor in 3 or more installments and 20 or less installments.

7. The process of recovering 3-hydroxypropionic acid according to claim 1, wherein: a content of the acid is 20 wt. % or more and 80 wt. % or less with respect to 100 wt. % of the 3-hydroxypropionate crystal.

8. The process of recovering 3-hydroxypropionic acid according to claim 1, the process further comprising, after the first washing the precipitate using a first washing liquid, second washing the first washed precipitate using a second washing liquid and reusing the used second washing liquid.

9. The process of recovering 3-hydroxypropionic acid according to claim 8, wherein: at least one washing liquid selected from the first washing liquid and the second washing liquid is reused as a solvent in the preparing of the solution containing 3-hydroxypropionate crystal separated from the concentrate.

10. The process of recovering 3-hydroxypropionic acid according to claim 8, wherein: at least one washing liquid selected from the first washing liquid and the second washing liquid is mixed with a filtrate in which the precipitate has been filtered to prepare a mixed liquid, and the 3-hydroxypropionic acid is recovered from the mixed liquid.

11. The process of recovering 3-hydroxypropionic acid according to claim 8, further comprising: fermenting a bacterium strain having 3-hydroxypropionic acid-producing ability to produce a 3-hydroxypropionic acid fermentation liquid; and concentrating the fermentation liquid to form the concentrate containing 3-hydroxypropionic acid, wherein at least one washing liquid selected from the first washing liquid and the second washing liquid is reused in the fermenting of a bacterium strain having 3-hydroxypropionic acid-producing ability to produce the 3-hydroxypropionic acid fermentation liquid.

12. The process of recovering 3-hydroxypropionic acid according to claim 11, wherein: the concentrating of the fermentation liquid to form the concentrate containing 3-hydroxypropionic acid is carried out by evaporating the fermentation liquid, and the moisture removed by the evaporation is liquefied and reused for at least one washing selected from the first washing and the second washing.

13. The process of recovering 3-hydroxypropionic acid according to claim 8, further comprising drying at least one of the first and second washed precipitates, wherein the moisture removed by the drying is liquefied and reused for at least one washing selected from the first washing and the second washing.

14. The process of recovering 3-hydroxypropionic acid according to claim 1, wherein: the precipitate is represented by the following structural formula 3:
Cation(Anion).Math.pH.sub.2O[Structural Formula 3] wherein, Cation is a cation of the alkali metal salt, Anion is an anion of the acid, and p is the number of water molecules in the hydrate, which is an integer of 1 or more.

15. The process of recovering 3-hydroxypropionic acid according to claim 1, wherein: a particle size of the precipitate is at least 1.0 ?m.

16. The process of recovering 3-hydroxypropionic acid according to claim 1, wherein: a moisture content of the precipitate is 150% or less.

17. The process of recovering 3-hydroxypropionic acid according to claim 1, wherein: the 3-hydroxypropionate crystal is represented by the following structural formula 1 or structural formula 2:
Cation(3HP).sub.n[Structural Formula 1]
Cation(3HP).sub.n.Math.mH.sub.2O[Structural Formula 2] wherein, Cation is a cation of the alkali metal salt, 3HP is 3-hydroxypropionic acid that binds to the cation, n is the number of 3HP that binds to the cation, which is an integer of 1 or more, and m is the number of water molecules in the hydrate, which is an integer of 1 or more.

18. The process of recovering 3-hydroxypropionic acid according to claim 1, wherein: the alkali metal salt is Ca(OH).sub.2, Mg(OH).sub.2, or a mixture thereof.

19. The process of recovering 3-hydroxypropionic acid according to claim 1, wherein: the 3-hydroxypropionate crystal has a particle size distribution D.sub.50 of 20 ?m or more and 90 ?m or less, and a (D.sub.90?D.sub.10)/D.sub.50 of 1.00 or more and 3.00 or less.

20. The process of recovering 3-hydroxypropionic acid according to claim 1, wherein: a recovery rate of 3-hydroxypropionic acid is at least 40%.

21. A slurry composition comprising a precipitate represented by the following structural formula 4 and 3-hydroxypropionic acid.
Cation(Anion).Math.pH.sub.2O[Structural Formula 4] wherein, Cation is Na.sup.+, Mg.sup.2+ or Ca.sup.2+, Anion is SO.sub.4.sup.2?, PO.sub.4.sup.3? or CO.sub.3.sup.2?, and p is the number of water molecules in the hydrate, which is an integer of 1 or more.

22. The slurry composition according to claim 21, wherein: a particle size of the precipitate is at least 1.0 ?m.

23. The slurry composition according to claim 21, wherein: a moisture content of the precipitate is 150% or less.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0151] FIG. 1 is a scanning electron microscope (SEM) photograph of the precipitate formed in Example 3.

[0152] FIG. 2 is a scanning electron microscope (SEM) photograph of the precipitate formed in Comparative Example 3.

[0153] FIG. 3 is a scanning electron microscope (SEM) photograph of the precipitate formed in Example 4.

[0154] FIG. 4 is a scanning electron microscope (SEM) photograph of the precipitate formed in Example 5.

[0155] Hereinafter, the present invention will be described in more detail with reference to examples. However, the following examples are for illustrative purposes only, and are not intended to limit the scope of the present invention.

Preparation Example 1: Preparation of Bacterium Strain for Producing 3-Hydroxypropionic Acid

[0156] Recombinant vectors into which genes encoding glycerol dehydratase and aldehyde dehydrogenase, which are known to produce 3-hydroxypropionic acid (3HP) using glycerol as a substrate, were introduced were manufactured. The prepared recombinant vector was introduced into E. coli W3110 strain to prepare a 3-hydroxypropionic acid-producing strain.

[0157] More specifically, a BtuR gene encoding adenosyltransferase was cloned into plasmid pCDF containing a gene (dhaB) encoding glycerol dehydratase, a gene (aldH) encoding aldehyde dehydrogenase and a gene (gdrAB) encoding glycerol dehydratase reactivase. The resulting pCDF_J23101_dhaB_gdrAB_J23100_aldH_btuR vector was introduced into strain W3110 (KCCM 40219) by an electroporation method using an electroporation device (Bio-Rad, Gene Pulser Xcell) to prepare 3-hydroxypropionic acid-producing strain. The process of preparing the 3-hydroxypropionic acid-producing strain of Preparation Example 1 and the vectors, primers, and enzymes used were carried out with reference to Example 1 of Korean Unexamined Patent Publication No. 10-2020-0051375, which is incorporated herein by reference.

Preparation Example 2: Preparation of Ca(3HP).SUB.2 .Crystal

[0158] The 3-hydroxypropionic acid-producing strain prepared in Preparation Example 1 was fermented and cultured at 35? C. in a 5 L fermenter using unpurified glycerol as a carbon source to produce 3-hydroxypropionic acid. In order to prevent the lowering of pH due to the production of 3-hydroxypropionic acid, calcium hydroxide (Ca(OH).sub.2), which is an alkali metal salt, was added to maintain the pH to be neutral during the fermentation.

[0159] After fermentation culture, cells were removed by centrifugation (4000 rpm, 10 minutes, 4? C.), and primary fermentation liquid purification (primary purification) was performed using activated carbon. Specifically, activated carbon was added to the fermentation liquid from which bacterial cells were removed by centrifugation, the mixture was well mixed, and then centrifuged again to separate the activated carbon. Then, the fermentation liquid from which the activated carbon was separated was filtered with a vacuum pump through a 0.7 um filter paper to purify the 3-hydroxypropionic acid fermentation liquid.

[0160] The concentration of 3-hydroxypropionic acid in the fermentation liquid after completion of the primary purification was a level of 50 to 100 g/L, and the fermentation liquid was concentrated to a concentration of 600 g/L using a rotary evaporator (50? C., 50 mbar) to prepare a concentrate, and ethanol was added in an amount of two times the volume of the concentrate, and stirred (300 rpm) at room temperature to produce Ca(3HP).sub.2 crystals. At this time, the concentration of the alkali metal salt in the concentrate was 493.3 g/L (based on Ca(OH).sub.2). The resulting crystals were washed three times with ethanol (EtOH) and dried in an oven at 50? C. to finally recover the crystals.

Comparative Example 1

[0161] 5.0 g of Ca(3HP).sub.2 crystal recovered in Preparation Example 2 was added to 13.5 ml of distilled water to prepare a Ca(3HP).sub.2 aqueous solution, which was stirred at a temperature of 60? C. and 350 rpm for 10 minutes. 2.5 g of a 95% sulfuric acid solution was added to the Ca(3HP).sub.2 aqueous solution at a uniform rate for 5 minutes so that the molar ratio of sulfur (S) to calcium (Ca) is 0.9, and further stirred for 30 minutes to form a slurry containing CaSO.sub.4 precipitate and 3-hydroxypropionic acid.

[0162] Filtration was performed using a filtration flask and a vacuum pump in order to separate the CaSO.sub.4 precipitate. Then, a filtrate (B) before washing was obtained in a filtering flask, and then the filtered CaSO.sub.4 precipitate was washed with 20 ml of distilled water, and then filtered to obtain a filtrate (C) after washing. Additionally, the result was washed with 40 ml of distilled water, and then filtered to obtain a second washing liquid (D). Then, the CaSO.sub.4 precipitate was dried in an oven at a temperature of 40? C. for 20 hours to finally obtain the dried CaSO.sub.4 precipitate.

Example 1

[0163] A filtrate before washing (G), a first washing liquid (H), a second wash liquid (I) and a dried CaSO.sub.4 precipitate were obtained in the same manner as in Comparative Example 1, except that in the preparation of a Ca(3HP).sub.2 aqueous solution, the first washing liquid (C) of Comparative Example 1 was reused instead of 13.5 ml of distilled water.

Test Example

[0164] 1. Measurement of the Concentration of 3-Hydroxypropionic Acid

[0165] For the filtrate before washing (B, G), first washing liquid (C, H), and second washing liquid (D, I) obtained in Example 1 and Comparative Example 1, the concentration of 3-hydroxypropionic acid was measured using a high-performance liquid chromatography (HPLC), and the results are shown in Table 1 below.

[0166] 2. Measurement of Recovery Rate of 3-Hydroxypropionic Acid

[0167] The recovery rate of 3-hydroxypropionic acid obtained in Example 1 and Comparative Example 1 was measured and calculated using a high-performance liquid chromatography (HPLC), and the results are shown in Table 1 below.

[0168] Specifically, the absolute amount (Y.sub.ref) of 3-hydroxypropionic acid in the Ca(3HP).sub.2 aqueous solution, the content (Y.sub.filtration) of 3-hydroxypropionic acid contained in the filtrate (B or G) before washing, the content (Y.sub.washing1) of 3-hydroxypropionic acid contained in the first washing liquid (C or H) and the content (Y.sub.washing2) of 3-hydroxypropionic acid contained in the second washing liquid (D or I) were measured by a high performance liquid chromatography (HPLC), which were substituted into the following Equations 2 to 4, respectively, to calculate the recovery rate of 3-hydroxypropionic acid.

Recovery rate (%) of 3-hydroxypropionic acid recovery (%) in the filtrate (B or G) before washing=Y.sub.filtration/Y.sub.ref*100[Equation 2]

Recovery rate (%) of 3-hydroxypropionic acid in the first washing liquid (C or H)=Y.sub.washing1/Y.sub.ref*100[Equation 3]

Recovery rate (%) of 3-hydroxypropionic acid in the second washing liquid (D or I)=Y.sub.washing2/Y.sub.ref*100[Equation 4]

[0169] In addition, assuming that 3-hydroxypropionic acid that was not recovered with the filtrate before washing and the first and second washing liquids remained in the CaSO.sub.4 precipitate, this was shown in Table 1 below as the recovery rate of 3-hydroxypropionic acid contained in the CaSO.sub.4 precipitate.

TABLE-US-00001 TABLE 1 Concentration Recovery rate of 3-hydroxy- of 3-hydroxy- propionic propionic acid (g/L) acid (%) Comparative Filtrate before 338.4 61.9 Example 1 washing (B) First washing 63.0 23.0 liquid (C) Second washing 8.5 6.4 liquid (D) CaSO.sub.4 8.7 precipitate Example 1 Filtrate before 382.2 66.0 washing (G) First washing 73.9 24.8 liquid (H) Second washing 10.4 7.1 liquid (I) CaSO.sub.4 2.1 precipitate

[0170] Referring to Table 1, it was confirmed that since Example 1 reused the first washing liquid (C) of Comparative Example 1 for preparing a Ca (3HP).sub.2 aqueous solution, Example 1 and Comparative Example 1 used the same amount of Ca(3HP).sub.2 crystals, but Example 1 showed significantly higher 3-hydroxypropionic acid concentrations in all filtrates and washing liquids compared to Comparative Example 1. This can be expected to be because 3-hydroxypropionic acid is not lost during the process but is circulated within the process.

Example 2

[0171] 6.12 g of Ca(3HP).sub.2 crystal recovered in Preparation Example 2 was added to 13 ml of distilled water to prepare 32.0 wt. % Ca(3HP).sub.2 aqueous solution, which was stirred at a temperature of 60? C. and 350 rpm for 10 minutes.

[0172] 2.5 g of a 95% sulfuric acid solution was added to the Ca(3HP).sub.2 aqueous solution at a uniform rate for 5 minutes so that the molar ratio of sulfur (S) to calcium (Ca) is 0.85, and further stirred for 30 minutes to form a slurry containing CaSO.sub.4 precipitate and 3-hydroxypropionic acid.

[0173] Filtration was performed using a filtration flask and a vacuum pump in order to separate the CaSO.sub.4 precipitate. Then, a filtrate (A) before washing was obtained in a filtering flask, and then the filtered CaSO.sub.4 precipitate was washed with 30 ml of distilled water, and then filtered to obtain a filtrate (B) after washing. Then, the CaSO.sub.4 precipitate was dried in an oven at a temperature of 40? C. for 20 hours to finally obtain the dried CaSO.sub.4 precipitate. Additionally, filtrates (A) and (B) containing 3-hydroxypropionic acid were obtained.

Example 3

[0174] A process of recovering 3-hydroxypropionic acid was carried out in the same manner as in Example 2, except that the filtered CaSO.sub.4 precipitate was washed with 250 ml of distilled water, instead of washing the filtered CaSO.sub.4 precipitate with 30 ml of distilled water.

Comparative Example 2

[0175] A process of recovering 3-hydroxypropionic acid was carried out in the same manner as in Example 2, except that a Ca(3HP).sub.2 aqueous solution was stirred at a temperature of 25? C., instead of stirring the Ca(3HP).sub.2 aqueous solution at a temperature of 60? C.

Comparative Example 3

[0176] A process of recovering 3-hydroxypropionic acid was carried out in the same manner as in Example 3, except that a Ca(3HP).sub.2 aqueous solution was stirred at a temperature of 25? C., instead of stirring the Ca(3HP).sub.2 aqueous solution at a temperature of 60? C.

Test Example

[0177] 1. Evaluation of Removal Rate of Calcium (Ca) Element

[0178] When converting the 3-hydroxypropionate crystal (Ca(3HP).sub.2 crystal) in Example 3 and Comparative Example 3 to 3-hydroxypropionic acid, CaSO.sub.4 precipitates were produced, and thus, the content of the calcium (Ca) element removed was measured by an inductively coupled plasma analysis.

[0179] Specifically, the content (X.sub.ref) of calcium (Ca) element contained in the 32.0 wt. % Ca (3HP).sub.2 aqueous solution, and the content (X.sub.filtration) of calcium (Ca) element contained in the filtrate (B) after washing were respectively analyzed, and the removal rate of the calcium (Ca) element was calculated according to the following Equation 5, and the results are shown in Table 2 below.

Removal rate of calcium (Ca) element (%)=(X.sub.ref?X.sub.filtration)/X.sub.ref*100[Equation 5]

[0180] 2. Measurement of Particle Size of Precipitate

[0181] The particle size of the CaSO.sub.4 precipitate formed in Example 3 and Comparative Example 3 was confirmed through a scanning electron microscope analysis, and the results are shown in Table 2 below.

[0182] At this time, the particle size of the CaSO.sub.4 precipitate was measured based on the straight-line distance between crystal planes with the longest distance among the straight-line distances between crystal planes contained in the precipitate.

[0183] On the other hand, FIG. 1 is a scanning electron microscope (SEM) photograph of the precipitate formed in Example 3, and FIG. 2 is a scanning electron microscope (SEM) photograph of the precipitate formed in Comparative Example 3.

[0184] 3. Measurement of Moisture Content of Precipitate

[0185] The weight before drying and the weight after drying of the CaSO.sub.4 precipitate formed in Example 3 and Comparative Example 3 were substituted into the following Equation 6 to calculate the moisture content of the precipitate, and the results are shown in Table 2 below.

Moisture content (wt. %)=(Weight of precipitate before drying?Weight of precipitate after drying)/(Weight of precipitate after drying)*100[Equation 6]

[0186] 4. Measurement of Recovery Rate of 3-Hydroxypropionic Acid

[0187] The recovery rate of 3-hydroxypropionic acid obtained in Example 2 and Comparative Example 2 was measured by a high-performance liquid chromatography (HPLC), and the results are shown in Table 3 below.

[0188] Specifically, the content (Y.sub.ref) of 3-hydroxypropionic acid contained in the 32.0 wt. % Ca(3HP).sub.2 aqueous solution, the content (Y.sub.filtration1) of 3-hydroxypropionic acid in the filtrate (A) before washing, and the content (Y.sub.filtration2) of 3-hydroxypropionic acid in the filtrate (B) after washing were measured by a high performance liquid chromatography (HPLC), which were respectively substituted into the following Equations 7 and 8 to calculate the recovery rates of 3-hydroxypropionic acid in the filtrate (A) before washing and the filtrate (B) after washing.

Recovery rate (%) of 3-hydroxypropionic acid in the filtrate (A) before washing (%)=Y.sub.filtration1/Y.sub.ref*100[Equation 7]

Recovery rate (%) of 3-hydroxypropionic acid in the filtrate (B) after washing=Y.sub.filtration2/Y.sub.ref*100[Equation 8 ]

TABLE-US-00002 TABLE 2 Removal rate Moisture of calcium Particle size content (Ca) element of precipitate of precipitate (%) (?m) (wt. %) Example 3 73.1 1.5-4.5 68.0 Comparative 76.8 0.2-2.0 175.0 Example 3

TABLE-US-00003 TABLE 3 Recovery rate of 3-hydroxypropionic acid (%) Example 2 Filtrate (A) before washing 62.5 Filtrate (B) after washing 28.4 Subtotal 90.9 Comparative Filtrate (A) before washing 34.7 Example 2 Filtrate (B) after washing 32.5 Subtotal 67.2

[0189] Referring to Tables 2 and 3, it was confirmed that the CaSO.sub.4 precipitate formed in Example 3 in which sulfuric acid was charged at a temperature of 60? C. had a larger particle size and a significantly lower moisture content than the CaSO.sub.4 precipitate formed in Comparative Example 3 in which sulfuric acid was charged at a temperature of 25? C. In addition, it was confirmed that Example 2, in which sulfuric acid was charged at a temperature of 60? C., had a significantly higher recovery rate of 3-hydroxypropionic acid than Comparative Example 2, in which sulfuric acid was charged at a temperature of 25? C.

Example 4

[0190] 5.8 g of Ca(3HP).sub.2 crystal recovered in Preparation Example 2 was added to 9.2 ml of distilled water, and stirred for 1 hour to prepare a Ca(3HP).sub.2 aqueous solution (concentration of 630 g/L).

[0191] 10.9 ml of distilled water was charged into a new flask, and heated up to a temperature of 60? C. using a heating mantle. After that, 240 mg of sulfuric acid was divided into 24 mg each and charged 10 times at intervals of 6 minutes into a flask containing the distilled water, and at the same time, the Ca(3HP).sub.2 aqueous solution was charged into the flask containing the distilled water at a rate of 0.25 g/min for 1 hour, and then stirred. Then, the result was further stirred for 30 minutes to form a slurry containing CaSO.sub.4 precipitate and 3-hydroxypropionic acid.

[0192] After that, the CaSO.sub.4 precipitate and the filtrate were separated using a filtration flask and a vacuum pump.

Example 5

[0193] 5.8 g of Ca(3HP).sub.2 crystal recovered in Preparation Example 2 were added to 9.2 ml of distilled water, and stirred for 1 hour to prepare a Ca(3HP).sub.2 aqueous solution.

[0194] 25.7 ml of distilled water was added to a new flask, and heated up to a temperature of 60? C. using a heating mantle. Then, 240 mg of sulfuric acid was divided into 48 mg each and charged 5 times at intervals of 12 minutes into the flask containing the distilled water, and at the same time, the Ca(3HP).sub.2 aqueous solution was charged into the flask containing the distilled water at a rate of 0.25 g/min for 1 hour, and then stirred. Then, the result was further stirred for 30 minutes to form a slurry containing CaSO.sub.4 precipitate and 3-hydroxypropionic acid.

[0195] After that, the CaSO.sub.4 precipitate and the filtrate were separated using a filtration flask and a vacuum pump.

Test Example

[0196] 1. Measurement of Particle Size of Precipitate

[0197] The particle size of the CaSO.sub.4 precipitate recovered in Examples 4 and 5 was confirmed through a scanning electron microscope analysis, and the results are shown in Table 4 below. At this time, the particle size of the CaSO.sub.4 precipitate was measured based on the straight-line distance between crystal planes with the longest distance among the straight-line distances between crystal planes contained in the precipitate. On the other hand, FIG. 3 is a scanning electron microscope (SEM) photograph of the precipitate formed in Example 4, and FIG. 4 is a scanning electron microscope (SEM) photograph of the precipitate formed in Example 5.

[0198] 2. Measurement of Recovery Rate of 3-Hydroxypropionic Acid

[0199] The recovery rate of 3-hydroxypropionic acid in Examples 4 and 5 was measured by a high performance liquid chromatography (HPLC), and the results are shown in Table 4 below.

[0200] Specifically, before being charged into the flask, the content (X) of 3-hydroxypropionic acid contained in the Ca(3HP).sub.2 aqueous solution, and the content (Y) of 3-hydroxypropionic acid in the filtrate were analyzed by HPLC, and then substituted into the following Equation 9 to calculate the recovery rate of 3-hydroxypropionic acid.

Recovery rate (%) of 3-hydroxypropionic acid=Y/X*100[Equation 9]

[0201] 3. Evaluation of Fluidity of Slurry

[0202] The fluidity of the slurries formed in Examples 4 and 5 was evaluated according to the following criteria, and the results are shown in Table 4 below.

[0203] <Judgment Criteria>

[0204] High: the volume of the slurry remaining inside the flask is 10% or less when pouring and taking out the slurry inside the flask without a washing solvent

[0205] Low: the volume of the slurry remaining inside the flask is greater than 10% when pouring and taking out the slurry inside the flask without a washing solvent

[0206] 4. Evaluation of Filtration Speed of Slurry

[0207] The filtration speed of the slurries formed in Examples 4 and 5 was evaluated according to the following criteria, and the results are shown in Table 4 below.

[0208] <Judgment Criteria>

[0209] Fast: the injection flow rate of the filtrate obtained in the filtration flask is 50 ml/min or more

[0210] Slow: the injection flow rate of the filtrate obtained in the filtration flask is less than 50 ml/min

TABLE-US-00004 TABLE 4 Particle size of Recovery rate precipitate of 3-hydroxypropionic Filtration (?m) acid (%) Fluidity speed Example 4 10~40 74.5 High Fast Example 5 30~140 84.1 High Fast

[0211] Referring to Table 4, it was confirmed that in the case of the CaSO.sub.4 precipitate formed in Examples 4 and 5, in which Ca(3HP).sub.2 aqueous solution was continuously charged and sulfuric acid was divisionally charged, the particle size was large, the fluidity of the precipitate was high, the filtration speed of the precipitate was fast, and the recovery rate of 3-hydroxypropionic acid was as high as 74.5% or more.