D-calcium pantothenate mother liquor recovery process

Abstract

The invention relates to the technical field of D-calcium pantothenate production, in particular to a D-calcium pantothenate mother liquor recovery process which comprises the following steps: concentrating collected D-calcium pantothenate mother liquor, then respectively collecting concentrated liquor and condensate, adding sodium salt into the condensate, stirring, standing for layering, and collecting the D-calcium pantothenate mother liquor. The collected supernatant is used as a D-calcium pantothenate crystallization solvent, the collected concentrated solution is diluted with water and then decolored, the collected decolored solution firstly passes through a cationic resin column, then the collected effluent passes through an anionic resin column, an eluent is adopted for elution treatment, the collected eluent is concentrated, ethyl alcohol is added into the collected concentrated solution, and the D-calcium pantothenate crystallization solvent is obtained. And adding a seed crystal after the system is turbid, cooling and growing the crystal for a period of time, cooling, carrying out suction filtration, and drying the collected crystal to obtain the high-yield and high-purity D-calcium pantothenate product.

Description

Technical Field

[0001] The invention relates to the technical field of D-calcium pantothenate production, in particular to a D-calcium pantothenate mother liquor recovery process. Background Art

[0002] Calcium pantothenate is a B vitamin and essential nutrient for normal biological growth. It is primarily used in medicine, food, and feed additives, and is a component of coenzyme A. In recent years, my country's feed industry has developed rapidly, and demand for D-calcium pantothenate has also increased dramatically, offering promising domestic and international market prospects and high economic returns.

[0003] The production technologies for calcium D-pantothenate primarily include chemical synthesis, enzymatic methods, and biofermentation. Currently, the first two methods are predominant in the current production process. However, traditional chemical synthesis of calcium D-pantothenate is complex, requiring resolution of the racemate to obtain D-pantothenate. Enzymatic methods require highly selective enzymes to obtain D-form of calcium D-pantothenate. Microbial fermentation, with its low production cost, low toxicity, and minimal pollution, has become the primary development direction for the industrial production of calcium D-pantothenate. Extraction of calcium D-pantothenate from the fermentation broth to obtain calcium pantothenate crystals primarily involves crystallization, which yields crystals of high chemical and optical purity. However, this method produces a mother liquor containing 15-25% calcium pantothenate, 5-15% water, 60-80% ethanol, and a small amount of pigment. Without effective treatment, this method inevitably results in resource waste. Therefore, effectively recovering high-yield, high-purity calcium D-pantothenate from the mother liquor remains an urgent technical challenge. Summary of the Invention

[0004] The technical problem to be solved by the present invention is: to address the deficiencies of the existing technology and provide a D-pantothenate calcium mother liquor recovery process, by which a D-pantothenate calcium product with high yield, high yield and high purity can be obtained.

[0005] In order to solve the above technical problems, the technical solution of the present invention is:

[0006] A D-calcium pantothenate mother liquor recovery process, the recovery process comprising the following steps:

[0007] (1) concentrating the collected D-calcium carbonate mother liquor, and collecting the concentrated liquid and the condensed liquid after condensation treatment respectively;

[0008] (2) taking the concentrated solution in step (1), diluting it with water, decolorizing it, filtering it, and collecting the decolorized solution for later use;

[0009] (3) taking the decolorized solution described in step (2), passing it into a cationic resin column, and collecting the effluent for later use;

[0010] (4) taking the effluent described in step (3), entering it into an anion resin column, eluting the anion resin with an eluent, collecting the eluate in sections, and stopping the collection when the D-pantothenate calcium content in the effluent is ≤50 mg / L; testing the eluates collected in sections separately, and combining the eluates with the D-pantothenate calcium content meeting the requirements;

[0011] (5) The eluate in step (4) is concentrated, ethanol is added to the collected concentrate until the system becomes turbid, and then seed crystals are added. The temperature is first lowered to grow the crystals, and then the temperature is lowered again and filtered. The collected crystals are dried to obtain the D-pantothenate calcium product.

[0012] As an improved technical solution, in step (1), the D-calcium carbonate mother liquor is concentrated until no liquid condenses out, and then water is added to the concentrated liquid to continue concentrating. The condensates after the two concentrations and condensations are combined, and then sodium salt is added to the condensate, stirred, and allowed to stand for stratification. The water content of the collected upper layer liquid is tested, and then sodium salt is further added to the upper layer liquid, stirred, and allowed to stand for stratification. The collected upper layer liquid is used as the crystallization solvent in step (5).

[0013] As an improved technical solution, in step (2), when the concentrated solution is diluted with water to a solid content of 5-10 wt%, activated carbon is added for decolorization, and the decolorization temperature is controlled to be 35-45° C. and the decolorization time is 45-55 min.

[0014] As an improved technical solution, the decolorizing solution in step (3) enters the cationic resin column at a flow rate of 1-2 BV / h, and the filler in the cationic resin is a macroporous strongly acidic cation exchange resin, a macroporous weakly acidic cation exchange resin, a macroporous weakly acidic phenyl propylene cation exchange resin or a strongly acidic styrene cation exchange resin.

[0015] As an improved technical solution, the effluent in step (4) enters the anion resin column at a flow rate of 0.5-1.0 BV / h, and the filler in the anion resin column is a macroporous weakly basic anion exchange resin, a macroporous strongly basic styrene-based anion exchange resin or a macroporous strongly basic acrylic anion exchange resin.

[0016] As an improved technical solution, the eluent in step (4) is a 2-4 wt% calcium chloride solution, and the flow rate of the eluent entering the anion resin column is 0.5-0.8 BV / h.

[0017] As an improved technical solution, in step (5), when the eluent is concentrated to a solid content of 300-400 g / L, 80-95 wt% ethanol is added, the temperature is first lowered to 25-30°C, crystallization is carried out for 0.5-1.0 h, and then the temperature is lowered to 10-15°C.

[0018] After adopting the above technical solution, the beneficial effects of the present invention are:

[0019] The method is to collect D-pantothenate calcium mother liquor and subject it to concentration treatment, and then collect the concentrated liquid and condensate respectively; wherein sodium salt is added to the condensate, stirred, and allowed to stand for stratification; the collected upper layer liquid is used as a D-pantothenate calcium crystallization solvent; the collected concentrated liquid is diluted with water and then decolorized; the collected decolorized liquid is first passed through a cationic resin column; then the collected effluent is passed through an anionic resin column and eluted with an eluent; the collected eluate is concentrated; ethanol is added to the collected concentrated liquid; crystal seeds are added after the system becomes turbid; the temperature is lowered for crystal growth for a period of time; then the temperature is lowered again, suction filtration is performed, and the collected crystals are dried to obtain a high-yield and high-purity D-pantothenate calcium product. DETAILED DESCRIPTION

[0020] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0021] Example 1

[0022] A D-calcium pantothenate mother liquor recovery process comprises the following steps:

[0023] (1) 100 L of D-calcium carbonate mother liquor with a D-pantothenate calcium content of 25 g / L was collected and concentrated at a temperature of 60°C and a vacuum degree of -0.095 MPa. The specific concentration operation was as follows: first, the D-calcium carbonate mother liquor was concentrated until no liquid condensed out, and then water was added to the concentrated liquid to continue concentrating. 90 kg of condensate after the two concentrations and condensations was combined, and then 90 kg of sodium salts (anhydrous Na2CO3, Na2HPO4, Na3PO4) were added at a mass ratio of 1:1. 4 (mixed in a mass ratio of 1:1:1) was added to the condensate and stirred for 2 hours, and the mixture was allowed to stand for stratification. The water content of the collected 67L upper liquid was detected (the mass of water was 16kg), and then sodium salt (anhydrous Na2CO3, Na2HPO4, and Na3PO4 were mixed in a mass ratio of 1:1:1) with a water content 3 times that of the upper liquid was added, and the mixture was stirred and allowed to stand for stratification. The collected upper liquid was used as the crystallization solvent in step (5), and 20L of the concentrated solution was collected for standby use;

[0024] (2) 20 L of the concentrated solution in step (1) was diluted with water to a solid content of 5 wt %, and then 1% activated carbon was added to the solid content of the concentrated solution for decolorization (the decolorization temperature was controlled at 35° C. and the decolorization time was 45 min). The solution was filtered and 240 L of the decolorized solution was collected for later use.

[0025] (3) Take 240 L of the decolorized liquid in step (2) and feed it into a 60 L cationic resin column (filler is D113 macroporous weakly acidic phenyl propylene cation exchange resin) at a flow rate of 1 BV / h, and collect 300 L of the effluent for later use;

[0026] (4) 300 L of the effluent from step (3) was taken and fed into an 80 L anion resin column (filler: D301 macroporous weakly basic anion exchange resin) at a flow rate of 0.5 BV / h. 2 wt% calcium chloride solution was used as an eluent and fed into the anion resin column at a flow rate of 0.5 BV / h for elution. 180 L of the collected eluate (it should be noted that the eluate was collected in sections and the collection was stopped when the D-pantothenate calcium content in the effluent was ≤50 mg / L; the eluates collected in sections were tested separately, and the eluates with the D-pantothenate calcium content meeting the requirements were combined) were set aside;

[0027] (5) 180 L of the eluate in step (4) was concentrated at 70° C. and a vacuum degree of -0.095 MPa to obtain 30 L of a concentrate having a D-pantothenate calcium content of 300 g / L. 80 wt% ethanol, which was 4 times the volume of the concentrate, was then added until the system became turbid. Seed crystals having a D-pantothenate calcium content of 0.1% of the concentrate were then added. The temperature was first lowered to 25° C. for crystal growth for 0.5 h, and then the temperature was further lowered by 10° C. and filtered. The collected crystals were dried to obtain the D-pantothenate calcium product.

[0028] Example 2

[0029] A D-calcium pantothenate mother liquor recovery process comprises the following steps:

[0030] (1) 100 L of D-calcium carbonate mother liquor with a D-pantothenate calcium content of 22 g / L was collected and concentrated at a temperature of 63°C and a vacuum degree of -0.095 MPa. The specific concentration operation was as follows: first, the D-calcium carbonate mother liquor was concentrated until no liquid condensed out, and then water was added to the concentrated liquid to continue concentrating. 88 kg of condensate after the two concentrations and condensations were combined, and then 105.6 kg of sodium salts (anhydrous Na2CO3, Na2HPO4, Na3P O4 is mixed in a mass ratio of 1:1:1) and added to the condensate for 2.5 hours of stirring and stratification. The collected 56L upper liquid is tested for its water content (the mass of water is 14kg), and then sodium salt (anhydrous Na2CO3, Na2HPO4, Na3PO4 is mixed in a mass ratio of 1:1:1) with a water content 3.5 times that of the upper liquid is added to the upper liquid, stirred, and stratified. The collected upper liquid is used as the crystallization solvent in step (5), and 18L of the concentrated solution is collected for standby use;

[0031] (2) 18 L of the concentrate from step (1) was diluted with water to a solid content of 6.5 wt %, and then 2% activated carbon was added to the solid content of the concentrate to perform decolorization treatment (the decolorization temperature was controlled at 38° C. and the decolorization time was 48 min). The decolorized solution was collected and 165 L was set aside.

[0032] (3) 165 L of the decolorized solution from step (2) was passed through a 60 L cationic resin column (TP207 perforated weakly acidic cation exchange resin) at a flow rate of 1.2 BV / h, and 225 L of the effluent was collected for later use;

[0033] (4) 225 L of the effluent from step (3) was taken and fed into an 80 L anion resin column (D354 macroporous weakly basic anion exchange resin) at a flow rate of 0.65 BV / h. 2.5 wt% calcium chloride solution was used as an eluent and fed into the anion resin column at a flow rate of 0.6 BV / h for elution. 190 L of the collected eluate (it should be noted that the eluate was collected in sections and the collection was stopped when the D-pantothenate calcium content in the effluent was ≤50 mg / L; the eluates collected in sections were tested separately, and the eluates with the D-pantothenate calcium content meeting the requirements were combined) were set aside;

[0034] (5) 190 L of the eluate in step (4) was concentrated at 70° C. and a vacuum degree of −0.095 MPa to obtain 31.5 L of a concentrate having a D-pantothenate calcium content of 320 g / L. 85 wt% ethanol, 4.5 times the volume of the concentrate, was then added until the system became turbid. Seed crystals having a D-pantothenate calcium content of 0.2% of the concentrate were then added. The temperature was first lowered to 26° C. for crystal growth for 0.65 h, and then the temperature was further lowered by 12° C. and filtered. The collected crystals were dried to obtain the D-pantothenate calcium product.

[0035] Example 3

[0036] A D-calcium pantothenate mother liquor recovery process comprises the following steps:

[0037] (1) 100 L of D-calcium carbonate mother liquor with a D-pantothenate calcium content of 25 g / L was collected and concentrated at a temperature of 65°C and a vacuum degree of -0.095 MPa. The specific concentration operation was as follows: the D-calcium carbonate mother liquor was first concentrated until no liquid condensed out, and then water was added to the concentrated liquid to continue concentrating. 92 kg of condensate after the two concentrations and condensations were combined, and then 120 kg of sodium salts (anhydrous Na2CO3, Na2HPO4, Na3 PO4 is mixed in a mass ratio of 1:1:1) and added to the condensate for 3 hours of stirring and stratification. The water content of the collected 54L upper liquid is detected (the mass of water is 12kg), and then sodium salt (anhydrous Na2CO3, Na2HPO4, and Na3PO4 are mixed in a mass ratio of 1:1:1) with a water content 4 times that of the upper liquid is added to the upper liquid, stirred, and stratified. The collected upper liquid is used as the crystallization solvent in step (5), and 22L of the concentrated liquid is collected for standby use;

[0038] (2) 22 L of the concentrate from step (1) was diluted with water to a solid content of 7.5 wt %, and then 3% activated carbon was added to the solid content of the concentrate to perform decolorization treatment (the decolorization temperature was controlled at 40° C. and the decolorization time was 50 min). The decolorized solution (176 L) was collected and set aside;

[0039] (3) 176 L of the decolorized solution from step (2) was passed through a 60 L cationic resin column (filled with D001 macroporous strongly acidic cation exchange resin) at a flow rate of 1.5 BV / h, and 240 L of the effluent was collected for later use;

[0040] (4) 240 L of the effluent from step (3) was taken and fed into an 80 L anion resin column (D201 macroporous strong basic styrene anion exchange resin) at a flow rate of 0.75 BV / h. 3 wt% calcium chloride solution was used as an eluent and fed into the anion resin column at a flow rate of 0.7 BV / h for elution. 190 L of the collected eluate (it should be noted that the eluate was collected in sections and the collection was stopped when the D-pantothenate calcium content in the effluent was ≤50 mg / L; the eluates collected in sections were tested separately, and the eluates with the D-pantothenate calcium content meeting the requirements were combined) were set aside;

[0041] (5) 190 L of the eluate in step (4) was concentrated at 70° C. and a vacuum degree of -0.095 MPa to obtain 32.5 L of a concentrate having a D-pantothenate calcium content of 350 g / L. 90 wt% ethanol, 5 times the volume of the concentrate, was then added until the system became turbid. Seed crystals having a D-pantothenate calcium content of 0.3% of the concentrate were then added. The temperature was first lowered to 27° C. for crystal growth for 0.8 h, and then the temperature was further lowered by 12° C. and filtered. The collected crystals were dried to obtain the D-pantothenate calcium product.

[0042] Example 4

[0043] A D-calcium pantothenate mother liquor recovery process comprises the following steps:

[0044] (1) 100 L of D-calcium carbonate mother liquor with a D-pantothenate calcium content of 24 g / L was collected and concentrated at a temperature of 68°C and a vacuum degree of -0.095 MPa. The specific concentration operation was as follows: the D-calcium carbonate mother liquor was first concentrated until no liquid condensed out, and then water was added to the concentrated liquid to continue concentrating. 89 kg of condensate after the two concentrations and condensations were combined, and then 125 kg of sodium salts (anhydrous Na2CO3, Na2HPO4, Na3PO4) were added at a mass ratio of 1:1.4. The mixture was added to the condensate and stirred for 3.5 hours, and the mixture was allowed to stand for stratification. The water content of the collected 68L upper liquid was detected (the mass of water was 18kg), and then sodium salt (anhydrous Na2CO3, Na2HPO4, and Na3PO4 were mixed in a mass ratio of 1:1:1) with a water content 4.5 times that of the upper liquid was added, and the mixture was stirred and allowed to stand for stratification. The collected upper liquid was used as the crystallization solvent in step (5), and 19.5L of the concentrated solution was collected for standby use;

[0045] (2) 19.5 L of the concentrate from step (1) was diluted with water to a solid content of 8.5 wt %, and then 4% activated carbon was added to the solid content of the concentrate to undergo decolorization treatment (the decolorization temperature was controlled at 42° C. and the decolorization time was 52 min). The decolorized solution was filtered and 140 L was collected for later use.

[0046] (3) 140 L of the decolorized solution from step (2) was passed through a 60 L cationic resin column (filled with 732 strong acid styrene cation exchange resin) at a flow rate of 1.8 BV / h, and 200 L of the collected effluent was set aside;

[0047] (4) 200 L of the effluent from step (3) was taken and fed into an 80 L anion resin column (filler: D290 macroporous adsorption strong basic styrene anion exchange resin) at a flow rate of 0.85 BV / h. 3.5 wt% calcium chloride solution was used as an eluent and fed into the anion resin column at a flow rate of 0.75 BV / h for elution. 175 L of the eluate was collected (it should be noted that the eluate was collected in sections and the collection was stopped when the D-pantothenate calcium content in the effluent was ≤50 mg / L; the eluates collected in sections were tested separately, and the eluates with the D-pantothenate calcium content meeting the requirements were combined) for later use;

[0048] (5) 175 L of the eluate in step (4) was concentrated at 70° C. and a vacuum degree of −0.095 MPa to obtain 28 L of a concentrate having a D-pantothenate calcium content of 380 g / L. 92 wt% ethanol, 5.5 times the volume of the concentrate, was then added until the system became turbid. Seed crystals having a D-pantothenate calcium content of 0.4% of the concentrate were then added. The temperature was first lowered to 29° C. for crystal growth for 0.9 h, and then the temperature was further lowered to 13.5° C. and filtered. The collected crystals were dried to obtain the D-pantothenate calcium product.

[0049] Example 5

[0050] A D-calcium pantothenate mother liquor recovery process comprises the following steps:

[0051] (1) 100 L of D-calcium carbonate mother liquor with a D-pantothenate calcium content of 24 g / L was collected and concentrated at a temperature of 70°C and a vacuum degree of -0.095 MPa. The specific concentration operation was as follows: the D-calcium carbonate mother liquor was first concentrated until no liquid condensed out, and then water was added to the concentrated liquid to continue concentrating. 92 kg of condensate after the two concentrations and condensations were combined, and then 138 kg of sodium salts (anhydrous Na2CO3, Na2HPO4, Na3P O4 is mixed in a mass ratio of 1:1:1) and added to the condensate for 4 hours of stirring and stratification. The water content of the collected 70L upper liquid is detected (the mass of water is 21kg), and then sodium salt (anhydrous Na2CO3, Na2HPO4, and Na3PO4 are mixed in a mass ratio of 1:1:1) with a water content 5 times that of the upper liquid is added to the upper liquid, stirred, and stratified. The collected upper liquid is used as the crystallization solvent in step (5), and 18.5L of the concentrated solution is collected for standby use;

[0052] (2) 18.5 L of the concentrate from step (1) was diluted with water to a solid content of 10 wt %, and then 5% activated carbon was added to the solid content of the concentrate to perform decolorization treatment (the decolorization temperature was controlled at 45° C. and the decolorization time was 55 min). The decolorized solution was filtered and 120 L was collected for later use.

[0053] (3) Take 120 L of the decolorized solution in step (2) and feed it into a 60 L cationic resin column (filler: D001 macroporous strongly acidic cation exchange resin) at a flow rate of 2 BV / h. Collect 185 L of the effluent for later use.

[0054] (4) 185 L of the effluent from step (3) was taken and fed into an 80 L anion resin column (filler: D730 macroporous strongly basic acrylic anion exchange resin) at a flow rate of 1.0 BV / h. 4 wt% calcium chloride solution was used as an eluent and fed into the anion resin column at a flow rate of 0.8 BV / h for elution. 182 L of the collected eluate (it should be noted that the eluate was collected in sections and the collection was stopped when the D-pantothenate calcium content in the effluent was ≤50 mg / L; the eluates collected in sections were tested separately, and the eluates with the D-pantothenate calcium content meeting the requirements were combined) were set aside;

[0055] (5) 182 L of the eluate in step (4) was concentrated at 70° C. and a vacuum degree of −0.095 MPa to obtain 26 L of a concentrate having a D-pantothenate calcium content of 400 g / L. 95 wt% ethanol in an amount 6 times the volume of the concentrate was then added until the system became turbid. Seed crystals having a D-pantothenate calcium content of 0.5% of the concentrate were then added. The mixture was cooled to 30° C. and allowed to grow for 1.0 h. The mixture was then cooled again by 15° C. and filtered. The collected crystals were dried to obtain the D-pantothenate calcium product.

[0056] To better demonstrate that the process of the present invention can produce a high-yield, high-yield, and high-purity D-pantothenate calcium product, the following comparative examples are provided with reference to Example 3. The yields, yields, and purities of D-pantothenate calcium in Examples 1-5 and the comparative examples are shown in Table 1.

[0057] Comparative Example 1

[0058] The difference from Example 3 is that the decolorization temperature in step (2) is controlled to 30° C., and the other operations are the same.

[0059] Comparative Example 2

[0060] The difference from Example 3 is that the decolorization temperature in step (2) is controlled to 50° C., and the other operations are the same.

[0061] Comparative Example 3

[0062] The difference from Example 3 is that in step (3), the decolorizing solution enters the cationic resin column at a flow rate of 2.5 BV / h, and the other operations are the same.

[0063] Comparative Example 4

[0064] The difference from Example 3 is that in step (4), the effluent enters the anion resin column at a flow rate of 1.5 BV / h, and the other operations are the same.

[0065] Comparative Example 5

[0066] The difference from Example 3 is that the eluent in step (4) is a 1 wt% calcium chloride solution, and the other operations are the same.

[0067] Comparative Example 6

[0068] The difference from Example 3 is that the concentration of ethanol added in step (5) is 75 wt %, and the other operations are the same.

[0069] Comparative Example 7

[0070] The difference from Example 3 is that in step (5), ethanol is added until the system becomes turbid and then the temperature is directly lowered to 12° C. The rest of the operations are the same.

[0071] Comparative Example 8

[0072] The difference from Example 3 is that the flow rate of the eluent entering the anion resin column in step (4) is 1.2 BV / h, and the other operations are the same.

[0073] Comparative Example 9

[0074] The difference from Example 3 is that in step (5), the temperature is first lowered to 22° C. for crystal growth, and the remaining operations are the same.

[0075] Comparative Example 10

[0076] The difference from Example 3 is that in step (5), the temperature is first lowered to 32° C. for crystal growth, and the remaining operations are the same.

[0077] Comparative Example 11

[0078] The difference from Example 3 is that the temperature is lowered to 8° C. after the crystal growing is completed in step (5), and the rest of the operations are the same.

[0079] Comparative Example 12

[0080] The difference from Example 3 is that the temperature is lowered to 18° C. after the crystal growing is completed in step (5), and the rest of the operations are the same.

[0081] Comparative Example 13

[0082] The difference from Example 3 is that the filler in the cationic resin column in step (3) is Ni Sepharose affinity chromatography column resin, and the other operations are the same.

[0083] Comparative Example 14

[0084] The difference from Example 3 is that the filler in the anion resin column in step (4) is GST affinity chromatography column resin, and the other operations are the same.

[0085] Comparative Example 15

[0086] The difference from Example 3 is that the eluate in step (4) is not collected in sections and merged together, but all the eluate is collected together, and the rest of the operations are the same.

[0087] Table 1

[0088]

[0089]

[0090] From the data in Table 1, it can be found that the yield, yield, purity and color of the D-calcium pantothenate product obtained by adopting the recovery process of Example 3 of the present invention are better than those of other examples and comparative examples.

[0091] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A D-pantothenate calcium mother liquor recovery process, characterized in that: The recovery process comprises the following steps: (1) concentrating the collected D-calcium carbonate mother liquor, and collecting the concentrated liquid and the condensed liquid after condensation treatment respectively; (2) taking the concentrated solution in step (1), diluting it with water, decolorizing it, filtering it, and collecting the decolorized solution for later use; (3) taking the decolorized solution described in step (2), passing it into a cationic resin column, and collecting the effluent for later use; (4) taking the effluent described in step (3), entering it into an anion resin column, eluting the anion resin with an eluent, collecting the eluate in sections, and stopping the collection when the D-pantothenate calcium content in the effluent is ≤50 mg / L; testing the eluates collected in sections separately, and combining the eluates with the D-pantothenate calcium content meeting the requirements; (5) The eluate in step (4) is concentrated, ethanol is added to the collected concentrate until the system becomes turbid, and then seed crystals are added. The temperature is first lowered to grow the crystals, and then the temperature is lowered again and filtered. The collected crystals are dried to obtain the D-pantothenate calcium product.

2. A D-calcium pantothenate mother liquor recovery process according to claim 1, characterized in that, In step (1), the D-calcium carbonate mother liquor is concentrated until no liquid condenses out, and then water is added to the concentrated liquid to continue concentrating. The condensates after the two concentrations and condensations are combined, and then sodium salt is added to the condensate, stirred, and allowed to stand for stratification. The water content of the collected upper layer liquid is detected, and then sodium salt is further added to the upper layer liquid, stirred, and allowed to stand for stratification. The collected upper layer liquid is used as the crystallization solvent in step (5).

3. A D-pantothenate calcium mother liquor recovery process according to claim 1, characterized in that, When the concentrated solution in step (2) is diluted with water to a solid content of 5-10 wt%, activated carbon is added for decolorization. The decolorization temperature is controlled at 35-45° C. and the decolorization time is 45-55 min.

4. A D-pantothenate calcium mother liquor recovery process according to claim 1, characterized in that, In step (3), the decolorizing solution enters the cationic resin column at a flow rate of 1-2 BV / h, and the filler in the cationic resin is a macroporous strongly acidic cation exchange resin, a macroporous weakly acidic cation exchange resin, a macroporous weakly acidic phenyl propylene cation exchange resin or a strongly acidic styrene cation exchange resin.

5. A D-pantothenate calcium mother liquor recovery process according to claim 1, characterized in that, The effluent in step (4) enters the anion resin column at a flow rate of 0.5-1.0 BV / h, and the filler in the anion resin column is a macroporous weakly basic anion exchange resin, a macroporous strongly basic styrene-based anion exchange resin or a macroporous strongly basic acrylic anion exchange resin.

6. A D-pantothenate calcium mother liquor recovery process according to claim 1, characterized in that, The eluent in step (4) is a 2-4 wt% calcium chloride solution, and the flow rate of the eluent entering the anion resin column is 0.5-0.8 BV / h.

7. A D-pantothenate calcium mother liquor recovery process according to claim 1, characterized in that, When the eluate in step (5) is concentrated to a solid content of 300-400 g / L, 80-95 wt% ethanol is added, the temperature is first lowered to 25-30° C., crystallization is carried out for 0.5-1.0 h, and then the temperature is lowered to 10-15° C.

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