CN102390877B - Treatment method of calcium hydrogen citrate washes and preparation method of citric acid - Google Patents
Treatment method of calcium hydrogen citrate washes and preparation method of citric acid Download PDFInfo
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Abstract
The invention provides a treatment method of calcium hydrogen citrate washes, wherein the calcium hydrogen citrate washes is wastewater generated by washing calcium hydrogen citrate solids, and calculated by citric acid monohydrate, the content of the citric acid in the calcium hydrogen citrate washes is less than 1 percent by weight. The treatment method disclosed by the invention comprises the following step of: washing solid acid sludge obtained by solid-liquid separation of citric acid fermentation liquor by using the calcium hydrogen citrate washes. The invention also provides a preparation method of the citric acid, which comprises the following step of: washing the solid acid sludge obtained by solid-liquid separation of citric acid fermentation liquor by using the calcium hydrogen citrate washes. According to the method disclosed by the invention, the calcium hydrogen citrate washes can be effectively treated, the pressure to the environment in the citric acid preparation process can be also reduced, the preparation cost of the citric acid is reduced, and the citric acid yield is increased.
Description
Technical field
The present invention relates to a kind for the treatment of process of calcium hydrogen citrate washes and the preparation method of citric acid.
Background technology
Citric acid is first acid in the organic acid, because the excellent properties of the aspects such as physics, chemistry is widely used in the industrial circles such as medicine, chemistry, electronics, weaving, oil, leather, building, photography, plastics, casting and pottery.
The extracting method of domestic present citric acid is mainly calcium salt method, namely with certain density calcium carbonate serosity and citric acid fermentation aqueous solution reaction, generate citrate of lime, standing demix obtains the useless syrup in upper strata and lower floor's citrate of lime, by adopting the mode of upper waste discharge syrup, remove wherein impurity, the final decyclization of useless syrup is protected and is processed, and the citrate of lime solid enters subsequent processing and processes, as generating citric acid after obtaining purifying after calcium hydrogen citrate and the acidolysis with the citric acid fermentation aqueous solution reaction again.
But, in the process of citric acid fermentation broth solid-liquid separation, in order to guarantee residual the least possible citric acid in the citric acid thalline acid sludge, need to wash the citric acid acid sludge, normally used washing water are that temperature is 70-75 ℃ tap water.Like this, use a large amount of 70-75 ℃ tap water to wash, not only caused the waste on the resource, also improved the preparation cost of citric acid.
In addition, adopt the calcium salt extraction method from citric acid fermentation broth, to obtain in the citric acid process, in order to guarantee the quality of calcium hydrogen citrate, to wash the calcium hydrogen citrate crystal with a large amount of tap water (70-75 ℃ of hot water), it is final when citric acid content is lower than 1 % by weight in the washing water, this part washing water directly is discharged into environmental protection treatment, and this has increased processing cost at the pressure that has virtually strengthened environment.
Summary of the invention
The purpose of this invention is to provide a kind for the treatment of process of calcium hydrogen citrate washes and a kind of preparation method of citric acid.Adopt this treatment process not only can effectively process calcium hydrogen citrate washes, and can reduce in the citric acid generative process pressure to environment, reduce the citric acid manufacturing cost, improve the citric acid yield.
The present inventor is surprised to find that, when the content of citric acid in the washes of washing calcium hydrogen citrate during less than 1 % by weight, can be for the solid acid sludge after the washing citric acid fermentation broth solid-liquid separation, the subsequent technique of citric acid and the quality of citric acid are not affected, and can improve citric acid yield.
Namely the invention provides a kind for the treatment of process of calcium hydrogen citrate washes, the waste water that described calcium hydrogen citrate washes produces for washing calcium hydrogen citrate solid, in Citric acid monohydrate Food grade, the content of citric acid is less than 1 % by weight in the described calcium hydrogen citrate washes, it is characterized in that, the method comprises described calcium hydrogen citrate washes is used for solid acid sludge after the washing citric acid fermentation broth solid-liquid separation.
The present invention also provides a kind of preparation method of citric acid, and the method may further comprise the steps:
1) with the citric acid fermentation broth solid-liquid separation, obtain clear liquid and solid acid sludge, the solid acid sludge is washed, and the washing water after will washing and clear liquid obtained above merging, obtain citric acid fermentation aqueous solution;
2) citric acid in making citric acid fermentation aqueous solution is converted under the condition of citrate of lime and carries out the first contact reacts with the described citric acid fermentation aqueous solution of a part and calcium carbonate serosity, and the product after the first contact reacts carried out solid-liquid separation, obtain the solid phase citrate of lime;
3) with step 2) the solid phase citrate of lime that obtains and the described citric acid fermentation aqueous solution of another part carry out the second contact reacts citrate of lime is converted under the condition of calcium hydrogen citrate, and the product after the second contact reacts carried out solid-liquid separation, obtain in solid phase calcium hydrogen citrate and the secondary and mother liquor, and the solid phase calcium hydrogen citrate washed, collect and obtain the content of citric acid less than calcium hydrogen citrate washes and the calcium hydrogen citrate of 1 % by weight;
4) with step 3) the calcium hydrogen citrate acidolysis that obtains obtains citric acid;
Wherein, to step 1) in the solid acid sludge that obtains to wash used washing water be described calcium hydrogen citrate washes.
The method according to this invention compared with prior art has the following advantages:
1) with calcium hydrogen citrate washes of the present invention as the washing water of solid acid sludge, obviously reduce the consumption of former water and greatly reduce the quantity discharged of waste water, alleviated environmental protection pressure, reduced the environmental protection treatment expense.
2) because the citric acid in the calcium hydrogen citrate washes of the present invention has also obtained utilization, the minimizing of wastewater discharge also greatly reduces the loss of citric acid;
3) because the temperature of calcium hydrogen citrate washes is 70-75 ℃, the temperature required with prior art washing solid acid sludge is suitable, therefore use calcium hydrogen citrate washes that the solid acid sludge is washed and need not external heat source and heat, reduced the consumption of the energy.
Embodiment
The invention provides a kind for the treatment of process of calcium hydrogen citrate washes, the waste water that described calcium hydrogen citrate washes produces for washing calcium hydrogen citrate solid, in Citric acid monohydrate Food grade, the content of citric acid is less than 1 % by weight in the described calcium hydrogen citrate washes, it is characterized in that, the method comprises described calcium hydrogen citrate washes is used for solid acid sludge after the washing citric acid fermentation broth solid-liquid separation.
Treatment in accordance with the present invention method, described calcium hydrogen citrate washes are to wash the content of the citric acid that produces in the calcium hydrogen citrate solid process in the calcium salt method less than the waste water of 1 % by weight (in Citric acid monohydrate Food grade).The content of citric acid is the 0.5-0.9 % by weight in the preferred described calcium hydrogen citrate washes; More preferably the content of citric acid is the 0.6-0.8 % by weight in the described calcium hydrogen citrate washes.
Above-mentioned calcium hydrogen citrate washes can obtain by the content of the citric acid in the monitoring calcium hydrogen citrate washes.For example: can in washing process, carry out Real-Time Monitoring by high pressure liquid chromatography to washing water, collect as required.This monitoring method is well known in the art.
Treatment in accordance with the present invention method, the preparation of described citric acid fermentation broth can adopt and well known to a person skilled in the art that the whole bag of tricks prepares, and for example maize raw material are pulverized, and the crushed products that obtains is liquefied, and fermentation obtains citric acid fermentation broth.Generally speaking, the content of citric acid can be the 12-14 % by weight in the described citric acid fermentation broth.Described solid acid sludge is that the citric acid fermentation broth solid-liquid separation is obtained solid phase.
The treatment in accordance with the present invention method, the temperature of described calcium hydrogen citrate washes is 70-75 ℃, need not external heat source and heats, and can be directly used in the solid acid sludge after the washing citric acid fermentation broth solid-liquid separation.The consumption of described calcium hydrogen citrate washes can be selected according to the volume of citric acid fermentation broth.In the preferred situation, with respect to 1m
3Citric acid fermentation broth, the consumption of described calcium hydrogen citrate washes is 0.1-0.4m
3Under the prerequisite that guarantees washing effect, consider from cost, more preferably with respect to 1m
3Citric acid fermentation broth, the consumption of described calcium hydrogen citrate washes is 0.2-0.3m
3
In the present invention, can be the whole bag of tricks known in those skilled in the art to the washing methods of solid acid sludge.For example can be the solid acid sludge that will carry out through filter press with the citric acid fermentation broth of bacterium slag obtaining after the solid-liquid separation and described calcium hydrogen citrate washes mixing after 10-20 minute, carry out the liquid phase that obtains after the solid-liquid separation through filter press again; Also can use described calcium hydrogen citrate washes to carry out drip washing.Generalized case, the described content of washing Citric acid monohydrate Food grade in the acid sludge acid solution is the 2-3 % by weight.
The treatment in accordance with the present invention method, in the preferred situation, described calcium hydrogen citrate solid is that calcium salt method prepares the calcium hydrogen citrate solid that obtains through solid-liquid separation in the citric acid process.
The present invention also provides a kind of preparation method of citric acid, and the method may further comprise the steps:
1) with the citric acid fermentation broth solid-liquid separation, obtain clear liquid and solid acid sludge, the solid acid sludge is washed, and the washing water after will washing and clear liquid obtained above merging, obtain citric acid fermentation aqueous solution;
2) citric acid in making citric acid fermentation aqueous solution is converted under the condition of citrate of lime and carries out the first contact reacts with the described citric acid fermentation aqueous solution of a part and calcium carbonate serosity, and the product after the first contact reacts carried out solid-liquid separation, obtain the solid phase citrate of lime;
3) with step 2) the solid phase citrate of lime that obtains and the described citric acid fermentation aqueous solution of another part carry out the second contact reacts citrate of lime is converted under the condition of calcium hydrogen citrate, and the product after the second contact reacts carried out solid-liquid separation, obtain in solid phase calcium hydrogen citrate and the secondary and mother liquor, and the solid phase calcium hydrogen citrate washed, collect and obtain the content of citric acid less than calcium hydrogen citrate washes and the calcium hydrogen citrate of 1 % by weight;
4) with step 3) the calcium hydrogen citrate acidolysis that obtains obtains citric acid;
Wherein, to step 1) in the solid acid sludge that obtains to wash used washing water be described calcium hydrogen citrate washes.
Even since the present invention relate generally to improvement to the recycle of waste water with above-mentioned calcium hydrogen citrate washes to step 1) in the solid acid sludge that obtains wash and the back will be described in the secondary with the recycling of mother liquor, therefore other steps that this preparation method related to do not have special requirement, can carry out with reference to prior art.For example, operation and the condition of the preparation of citric acid fermentation broth and solid-liquid separation, the first contact reacts and the second contact reacts, solid-liquid separation etc. all can be carried out with reference to prior art.
According to citric acid preparation method of the present invention, the preparation of described citric acid fermentation broth can be adopted and well known to a person skilled in the art that the whole bag of tricks prepares, for example maize raw material is pulverized, the crushed products that obtains is liquefied, fermentation obtains citric acid fermentation broth.
According to citric acid preparation method of the present invention, comprise step 1) in the citric acid fermentation broth solid-liquid separation, obtain clear liquid and solid acid sludge.Described solid-liquid separation can adopt and well known to a person skilled in the art the whole bag of tricks.Such as filter, centrifugal etc.
According to citric acid preparation method of the present invention, step 1) washing water that described in the solid acid sludge washed are described calcium hydrogen citrate washes, preferably use step 3) the gained washing water wash described solid acid sludge as described calcium hydrogen citrate washes.
According to citric acid preparation method of the present invention, the compound method of calcium carbonate serosity step 2) comprises: under agitation, the pH value is less than or equal to 4 the lemon aqueous acid that contains and carries out first with calcium carbonate and mix, obtain the pH value and be the mixture of 4.8-5.2; The described first time of mixing was not less than 5 minutes; The pH value is mixed for the mixture of 4.8-5.2 carries out second with calcium carbonate, obtain calcium carbonate serosity.When the calcium carbonate serosity that adopts above-mentioned method to obtain carries out calcium salt method extraction citric acid, can not cause the problem that the citrate of lime crystal grain is loose, slurries solid-liquid volume ratio is large that obtains, help to improve the yield of citric acid.
According to citric acid preparation method of the present invention, the described lemon aqueous acid that contains can be the various lemon aqueous acids that contain, for example, the rare aqueous citric acid solution that in preparation citric acid process, produces, under the preferable case, in order to reduce the amount of waste water, and improve the citric acid yield, the preferred described lemon aqueous acid that contains is for adopting calcium salt method to prepare in the secondary that produces in the citric acid process and mother liquor; More preferably with step 3) in the secondary that obtains and mother liquor as the described lemon aqueous acid that contains.
Generally speaking, the described pH value that contains the lemon aqueous acid is less than or equal to 4, is preferably 2.5-3.5.In Citric acid monohydrate Food grade, the described content that contains citric acid in the lemon aqueous acid is generally the 1-5 % by weight.Because under the preferable case, from the secondary that produces in the citric acid production process and the temperature of mother liquor be generally 50-60 ℃, therefore, need not the temperature requirement that other heating namely can be satisfied above-mentioned mixing.
According to citric acid preparation method of the present invention, the pH value is less than or equal to 4 contain lemon aqueous acid and calcium carbonate and carries out first when mixing, calcium carbonate can be solid form, it also can be the form of calcium carbonate serosity (aqueous slurry), as long as can reach the purpose of regulating the pH value that contains the lemon aqueous acid, and guarantee the pH value of the mixture that obtains is got final product for 4.8-5.2.And the present invention is not particularly limited the amount of described calcium carbonate, can select according to practical situation, is 4.5-5.4 as long as satisfy the pH value that makes the mixture that obtains, and more preferably 4.8-5.2 gets final product.
According to citric acid preparation method of the present invention, the pH value is less than or equal to 4 the lemon aqueous acid that contains and carries out the temperature and time that the first condition of mixing generally comprises mixing with calcium carbonate.The selectable range of the described first temperature of mixing is wider, generally, can be 40-80 ℃, is preferably 50-70 ℃.The selectable range of the described first time of mixing is wider, under the preferable case, less than 50 minutes, can fully react the generation citrate of lime in order to guarantee the citric acid in the clear liquid, can guarantee that again citrate of lime class is not destroyed, the preferred reaction times is 20-30 minute.
According to citric acid preparation method of the present invention, will contain the mode that the lemon aqueous acid mixes with calcium carbonate and be not particularly limited, for example, can be static mixing, also can be dynamic mixing, also or the combination of two kinds of hybrid modes.Described mixing can under agitation be carried out, and stirring velocity can in very large range change, and contains the lemon aqueous acid and calcium carbonate fully mixes as long as make.
According to citric acid preparation method of the present invention, the pH value that obtains is carried out the temperature and time that the second condition of mixing generally comprises mixing for the mixture of 4.8-5.2 with calcium carbonate.The selectable range of the temperature of described mixing is wider, generally, can be 50-80 ℃, is preferably 55-65 ℃.The selectable range of the time of described mixing is wider, generally, can be 30-120 minute, is preferably 40-60 minute.
The pH value is carried out second when mixing for the mixture of 4.8-5.2 and calcium carbonate, calcium carbonate can be solid form, it also can be the form of calcium carbonate serosity (aqueous slurry), as long as can reach the solid content that makes calcium carbonate in the calcium carbonate serosity that obtains is the 30-50 % by weight, considering cost and efficient preferably adopt the calcium carbonate of solid form.Wherein, the pH value is that the selectable range of consumption of the mixture of 4.8-5.2 and calcium carbonate is wider, can select according to practical situation, and be the 30-50 % by weight as long as preferably make the solid content of calcium carbonate in the calcium carbonate serosity that obtains.
In order to be more conducive to make the mixture that contains citrate of lime fully to mix with calcium carbonate, to obtain uniform calcium carbonate serosity, under the preferable case, the pH value that the obtains mixture for 4.8-5.2 was under agitation carried out with mixing of calcium carbonate, the speed that stirs can in very large range change, and is preferably 40-50 rev/min.Mixing time can in very large range change, and is preferably 40-60 minute.
According to citric acid preparation method of the present invention, for the solid phase calcium carbonate in the calcium carbonate serosity is dispersed in the slurries, make the reaction of citric acid fermentation aqueous solution and calcium carbonate serosity more abundant, more complete, preferably before with citric acid fermentation aqueous solution and calcium carbonate serosity contact reacts, first calcium carbonate serosity is kept whipped state, stir the residence time for being no more than 2 hours.
According to citric acid preparation method of the present invention, in step (2), citric acid fermentation aqueous solution and calcium carbonate serosity are carried out the first catalytic condition can be the reaction conditions of routine, for example, described catalytic condition comprises that the pH value of reaction end is 4.5-5.4, is preferably 4.8-5.2; Temperature of reaction can be 70-85 ℃, is preferably 75-85 ℃; Reaction times can be 0.5-1.5 hour.
According to citric acid preparation method of the present invention, in step (3), citrate of lime is continued to carry out the second catalytic condition with citric acid fermentation aqueous solution can be the reaction conditions of routine, for example, described catalytic condition comprises that the pH value of reaction end is 2-4, is preferably 2.8-3.2; Temperature of reaction can be 70-80 ℃; Reaction times can be 2-3 hour.
According to citric acid preparation method of the present invention, the method is included in the solid phase calcium hydrogen citrate that step (3) is obtained and carries out before the acidolysis, calcium hydrogen citrate is washed, and the method for described washing can well known to a person skilled in the art method and condition for employing.For example, the employing temperature is that 75-80 ℃ washing water wash calcium hydrogen citrate, and collection obtains the content of citric acid less than described calcium hydrogen citrate washing water and the calcium hydrogen citrate of 1 % by weight.These calcium hydrogen citrate washing water can wash described solid acid sludge.
According to citric acid preparation method of the present invention, because the solid-liquid volume of the citrate of lime slurries that employing method of the present invention obtains is smaller, the general solid-liquid volume ratio ratio of liquid volume (solid volume with) be less than 3: 7, and the citrate of lime crystal grain is complete, particle is larger, is easy to separation.Citrate of lime after the separation continues and the citric acid fermentation aqueous solution reaction, the large and uniform particles of the particle of the calcium hydrogen citrate that obtains.Therefore, be conducive to the solid-liquid separation of calcium hydrogen citrate, can greatly reduce the consumption of the used washing water of washing calcium hydrogen citrate, and reduced the easy carbon multiple of calcium hydrogen citrate, improved purity.
According to citric acid preparation method of the present invention, be conventionally known to one of skill in the art with method and the condition of calcium hydrogen citrate acidolysis, for example, in step (4), the method that the solid phase calcium hydrogen citrate acidolysis that step (3) is obtained obtains citric acid comprises calcium hydrogen citrate is contacted with acidic solution.The condition of acidolysis generally comprises the pH value can be 1.5-1.8; The temperature of acidolysis can be 70-95 ℃, is preferably 80-90 ℃; The time of acidolysis can be 40-60 minute.The kind of the acidic solution that acidolysis is used can be for well known to a person skilled in the art various acidolysis acidic solutions, and generally, the functional quality percentage concentration is 98% the vitriol oil.
According to citric acid preparation method of the present invention, the method comprises that also the citric acid that step (4) is obtained carries out further removal of impurities, for example, ion-exchange and concentrated, crystallization and drying and other steps, described ion-exchange, concentrated, crystallization and dry concrete grammar and condition are conventionally known to one of skill in the art.
Except containing pigment, also has a small amount of Ca in the described Aoidolysed lemon liguor
2+, Mg
2+, Fe
3+, Cl
-, SO
4 2-Deng foreign ion, ion-exchange can be adopted the method for absorption exchange, removes pigment in the thick citric acid solution and harmful Ca by gac and Zeo-karb, anionite-exchange resin
2+, Mg
2+, Fe
3+, Cl
-Plasma obtains refining citric acid solution, and the ion exchange process parameter index can be destainer transmittance＞96%, ion exchange liquid transmittance＞96.5%, ion exchange liquid ion content Fe
3+＜4ppm, Cl
-＜4ppm, ion-exchange liquid acidity are about 35%.
Concentrated, crystallization, drying is to discharge after with a part of water vapor in the citric acid solution of low concentration with the method for heating, citric acid liquid (solution) is transformed into solid-liquid suspension under certain conditions, the citric acid crystal grain is separated with mother liquor, drying obtains the higher citric acid of concentration (water acid) or citric acid crystal grain (anhydrous acid), concentrated one, two, the triple effect temperature can be respectively 105 ℃, 90 ℃, 70 ℃, one, two, triple effect vacuum tightness can be respectively-10kPa,-40kPa,-90kPa, Citric Acid, usp, Anhydrous Powder production line blanking flow 5.5m
3Obtain citric acid crystal grain and anhydrous mother liquor about/h, and citric acid crystal grain drying machine (one section: 45 ℃, two sections: 40 ℃, three sections: 20 ℃, about 7 ℃ of frozen water temperature) utilize convection of air the moisture content vaporization of citric acid surface and drying; Citric acid monohydrate crystal particle drying machine (one section: 55 ℃, two sections: 45 ℃, three sections: 10 ℃, about 7 ℃ of frozen water temperature) utilize convection of air the moisture content vaporization of citric acid surface and drying.
By the following examples the present invention is further specified, but the present invention is not limited in following embodiment.
Used citric acid fermentation broth makes by the following method in following embodiment and the Comparative Examples: 0.872 kg corn is pulverized with SFSP series beater disintegrating machine, and obtaining average particulate diameter is 0.871 kilogram of crushed products of 2 millimeters (adopting the Accu Sizer TM 780 optics particle diameter detectors of U.S. PPS company to measure); 83 ± 1 ℃ of liquefaction temperatures, 93 ± 1 ℃ of secondary liquefaction control temperature are mixed crushed products and to be carried out steam ejection liquefaction with amylase, and holding time is 40-60 minute, and the pH value of described enzymolysis maintains 5.7-6.2; The α-amylase 0.7g/kg Semen Maydis powder (Novozymes Company buys) of adding vigor 〉=2000u/ml; Temperature is down to 38 ℃, and the inoculation biomass is the aspergillus niger of 18g/l (fermented liquid), the gained mixture under 37 ℃ in fermentor tank stir culture 65 hours, obtain citric acid fermentation broth.
In following examples, measure the easy charcoal multiple of calcium hydrogen citrate acid hydrolysis solution according to " foodstuff additive " citric acid GB1987-2007.
Calcium hydrogen citrate washes will contain in the calcium hydrogen citrate process that the slurries of calcium hydrogen citrate carry out obtaining after the solid-liquid separation for washing, collect the citric acid content that obtains less than the washing water of 1 % by weight.
In the secondary that produces in the citric acid production process and mother liquor carry out the liquid product that obtains after the solid-liquid separation for the slurries that will contain calcium hydrogen citrate.Generalized case, in Citric acid monohydrate Food grade, the content of citric acid is the 1.5-3 % by weight in the secondary that produces in the described citric acid production process and in the mother liquor.
The below will further describe in detail the present invention by specific embodiment.
Embodiment 1
(1) above-mentioned citric acid fermentation broth filtration is obtained clear liquid and solid acid sludge, (in Citric acid monohydrate Food grade, citric acid content is 0.80 % by weight, and temperature is 75 ℃ with calcium hydrogen citrate washes; Consumption: with respect to 1m
3Citric acid fermentation broth, use 0.20m
3Lemon acid hydrogen calcium washes, can use tap water to replace during startup or provided by other allied equipments, below identical) with after the solid acid sludge mixes 15 minutes, carry out obtaining washings after the solid-liquid separation through filter press again, the clear liquid that this washings and above-mentioned filtration are obtained merges and obtains citric acid fermentation aqueous solution (in Citric acid monohydrate Food grade, the citric acid content of mixed solution is 11 % by weight).
(2) with in the 500L citric acid secondary and mother liquor (the pH value is 2.8, in Citric acid monohydrate Food grade, the citric acid content of mixing acid is 3 % by weight, temperature is 67 ℃) directly send in the preset diluted acid tank with impeller pump, stir simultaneously, stirring velocity is 48 rev/mins, and with the calcium carbonate water slurries (flow velocity is 72L/h) of 38 % by weight join in the described preset diluted acid tank with the citric acid secondary in and mother liquor mix, mixing temperature is 64 ℃, the hybrid reaction time is 30min, and it is 5.2 that the consumption of calcium carbonate water slurries makes the pH value of the mixture that obtains.Be that 5.2 mixture is sent in the calcium carbonate serosity tank with impeller pump with the pH value that obtains, under agitation, add 250kg solid carbonic acid calcium, obtain the calcium carbonate serosity of 50 % by weight.
(3) calcium carbonate serosity that step (2) is obtained stirs, stirring the residence time is 1.2 hours, then with impeller pump described calcium carbonate serosity is sent in the neutralization tank and mixed with the part citric acid fermentation clear liquid in the step (1), the control endpoint pH is 5.2 o'clock, temperature of reaction is 80 ℃, reaction times is 1 hour, then carry out gravity settling separation, settling time is 30min, the citrate of lime slurries solid-liquid volume ratio (ratio of solid volume and liquid volume, below identical) be 3: 7, the useless syrup of the liquid phase that obtains is discharged by the top of neutralization tank, the neutralization tank bottom is the solid phase citrate of lime.
(4) under 80 ℃, the solid phase citrate of lime that step (3) is obtained continue with step (1) in the citric acid fermentation aqueous solution reaction, the control endpoint pH is 2.8, the reaction times is 2.8 hours, obtains containing the slurries of calcium hydrogen citrate; The slurries that will contain calcium hydrogen citrate carry out solid-liquid separation with conveyor drive, obtain solid phase calcium hydrogen citrate and liquid phase, this liquid phase is in the secondary that produces in the citric acid production process and mother liquor, be used for the preparation of next batch calcium carbonate serosity, then (temperature of tap water is 80 ℃ to use tap water, the consumption of tap water is 2.8 tons of/ton citric acids) wash calcium hydrogen citrate, and collect the washes that citric acid content is lower than 1 % by weight and be used for the solid acid sludge that the washing last consignment of obtains.
(5) under 95 ℃, the calcium hydrogen citrate after the washing that step (4) is obtained mixes with the vitriol oil (mass percent concentration is 98 % by weight), and control pH value is 1.8, reacts 60 minutes, and acidolysis obtains Aoidolysed lemon liguor; And be 95.25% according to the yield that following formula calculates citric acid.The easy carbon multiple of calcium hydrogen citrate acid hydrolysis solution sees Table 1.
(6) citric acid that obtains is carried out ion-exchange, concentrated, crystallization and drying and obtain the citric acid product.
The total amount of the clear middle citric acid of the total amount/citric acid fermentation of citric acid * 100% in the Aoidolysed lemon liguor that citric acid yield (%)=acidolysis obtains.
Embodiment 2
(1) above-mentioned citric acid fermentation broth filtration is obtained clear liquid and solid acid sludge, (in Citric acid monohydrate Food grade, citric acid content is 0.72 % by weight to the calcium hydrogen citrate washes that aforesaid method is obtained, and temperature is 75 ℃; Consumption: with respect to 1m
3Citric acid fermentation broth, use 0.3m
3Lemon acid hydrogen calcium washes) with after the solid acid sludge mixes 10 minutes, carry out the washings that obtains after the solid-liquid separation through filter press again, the clear liquid that this washings and above-mentioned filtration are obtained merges and obtains citric acid fermentation aqueous solution (in Citric acid monohydrate Food grade, the citric acid content of mixed solution is 10 % by weight).
(2) with in the 500L citric acid secondary and mother liquor (the pH value is 2.9, in Citric acid monohydrate Food grade, citric acid content is 2.7 % by weight, temperature is 68 ℃) directly send in the preset diluted acid tank with impeller pump, stir simultaneously, stirring velocity is 40 rev/mins, and with the calcium carbonate water slurries (flow velocity is 46L/h) of 42 % by weight, join in the described preset diluted acid tank with in the citric acid secondary and mix with mother liquor, mixing temperature is 62 ℃, the hybrid reaction time is 30min, and it is 4.8 that the consumption of calcium carbonate water slurries makes the pH value of the mixture that obtains.Be that 4.8 mixture is sent in the calcium carbonate serosity tank with impeller pump with the pH value that obtains, under agitation, add 220kg solid carbonic acid calcium, obtain the calcium carbonate serosity of 45 % by weight.
(3) calcium carbonate serosity that obtains in the step (2) is stirred, stirring the residence time is 1.5 hours, then with impeller pump described calcium carbonate serosity is sent in the neutralization tank with part citric acid clear liquid in the step (1) and mixed, the control endpoint pH is 5 o'clock, temperature of reaction is 78 ℃, reaction times is 0.7 hour, then carry out gravity settling separation, settling time is 30min, citrate of lime slurries solid-liquid volume ratio is 3: 7, the useless syrup of the liquid phase that obtains is discharged by the top of neutralization tank, and the neutralization tank bottom is the solid phase citrate of lime;
(4) under 75 ℃, the solid phase citrate of lime that step (3) is obtained continues and above-mentioned citric acid fermentation aqueous solution reaction, and the control endpoint pH is 2.9, reacts 2.5 hours, obtains containing the slurries of calcium hydrogen citrate; The slurries that will contain calcium hydrogen citrate carry out solid-liquid separation with conveyor drive, the solid phase calcium hydrogen citrate and the liquid phase that obtain, this liquid phase is in the secondary that produces in the citric acid production process and mother liquor, be used for the preparation of next batch calcium carbonate serosity, then (temperature of tap water is 80 ℃ to use tap water, the consumption of tap water is 2.8 tons of/ton citric acids) wash calcium hydrogen citrate, and collect the washes that citric acid content is lower than 1 % by weight, be calcium hydrogen citrate washes and obtain the solid acid sludge for the washing last consignment of).
(5) under 85 ℃, the calcium hydrogen citrate after the washing that step (4) is obtained mixes with the vitriol oil (mass percent concentration is 98 % by weight), and control pH value is 1.6, reacts 50 minutes, and acidolysis obtains Aoidolysed lemon liguor; And be 95.2% according to the yield that the formula of EXPERIMENTAL EXAMPLE 1 calculates citric acid.The easy carbon multiple of calcium hydrogen citrate acid hydrolysis solution sees Table 1.
(6) citric acid that obtains is carried out ion-exchange, concentrated, crystallization and drying and obtain the citric acid product.
Embodiment 3
(1) above-mentioned citric acid fermentation broth filtration is obtained clear liquid and solid acid sludge, (in Citric acid monohydrate Food grade, citric acid content is 0.60 % by weight, and temperature is 75 ℃ with obtaining calcium hydrogen citrate washes among the embodiment 2; Consumption: with respect to 1m
3Citric acid fermentation broth, use 0.25m
3Lemon acid hydrogen calcium washes) with after the solid acid sludge mixes 15 minutes, carry out the washings that obtains after the solid-liquid separation through filter press again, the clear liquid that this washings and above-mentioned filtration are obtained merges and obtains citric acid fermentation aqueous solution (in Citric acid monohydrate Food grade, citric acid content is 12 % by weight).
(2) with in the 500L citric acid secondary and mother liquor (the pH value is 3, in Citric acid monohydrate Food grade, citric acid content is 2.5 % by weight, temperature is 65 ℃) directly send in the preset diluted acid tank with impeller pump, stir simultaneously, stirring velocity is 45 rev/mins, and with the calcium carbonate water slurries (flow velocity is 45L/h) of 40 % by weight join in the described preset diluted acid tank with the citric acid secondary in and mother liquor mix, mixing temperature is 60 ℃, the hybrid reaction time is 30min, and it is 5 that the consumption of calcium carbonate water slurries makes the pH value of the mixture that obtains; Be that 5 mixture is sent in the calcium carbonate serosity tank with impeller pump with the pH value that obtains, under agitation, add 220kg solid carbonic acid calcium, obtain the calcium carbonate serosity of 45 % by weight.
(3) calcium carbonate serosity that obtains in the step (2) is stirred, stirring the residence time is 1.8 hours, then with impeller pump described calcium carbonate serosity is sent in the neutralization tank and mixed with the part citric acid fermentation clear liquid in the step (1), the control endpoint pH is 4.8, temperature of reaction is 75 ℃, reaction times is 0.5 hour, then carry out gravity settling separation, settling time is 30min, citrate of lime slurries solid-liquid volume ratio is 3: 7, the useless syrup of the liquid phase that obtains is discharged by the top of neutralization tank, and the neutralization tank bottom is the solid phase citrate of lime.
(4) under 70 ℃, the solid phase citrate of lime that step (3) is obtained continue with step (1) in the citric acid fermentation aqueous solution reaction, the control endpoint pH is 3, the reaction times is 2 hours, obtains containing the slurries of calcium hydrogen citrate; The slurries that will contain calcium hydrogen citrate carry out solid-liquid separation with conveyor drive, obtain solid phase calcium hydrogen citrate and liquid phase, this liquid phase is in the secondary that produces in the citric acid production process and mother liquor, be used for the preparation of next batch calcium carbonate serosity, then (temperature of tap water is 80 ℃ to use tap water, the consumption of tap water is 2.8 tons of/ton citric acids) wash calcium hydrogen citrate, and collect the washes that citric acid content is lower than 1 % by weight and be used for the solid acid sludge that the washing last consignment of obtains).
(5) under 75 ℃, the calcium hydrogen citrate after the washing that step (4) is obtained mixes with the vitriol oil (mass percent concentration is 98 % by weight), and control pH value is 1.5, reacts 40 minutes, and acidolysis obtains Aoidolysed lemon liguor; And be 95.3% according to the yield that the formula of embodiment 1 calculates citric acid.The easy carbon multiple of calcium hydrogen citrate acid hydrolysis solution sees Table 1.
(6) citric acid that obtains is carried out ion-exchange, concentrated, crystallization and drying and obtain the citric acid product.
Comparative Examples 1
Produce citric acid according to EXPERIMENTAL EXAMPLE 3 described methods, different is, use 75 ℃ tap water to replace calcium hydrogen citrate washes in the step (1), obtain citric acid fermentation aqueous solution (in Citric acid monohydrate Food grade, the citric acid content of mixed solution is 11.7 % by weight); Step (2) is: in the calcium carbonate serosity tank, under agitation, the 500L tap water is mixed with 220kg solid carbonic acid calcium, mixing temperature is 62 ℃, is mixed with the calcium carbonate serosity that concentration is 45 % by weight; The solid-liquid volume ratio of citrate of lime slurries is 3: 7 in the step (3); In the step (4), with washing from the beginning calcium hydrogen citrate, the consumption of tap water is 2.8 tons of/ton citric acids; In the step (5), acidolysis obtains Aoidolysed lemon liguor, and the easy carbon multiple of calcium hydrogen citrate acid hydrolysis solution sees Table 1.And be 95.15% according to the yield that the formula of EXPERIMENTAL EXAMPLE 1 calculates citric acid.
Comparative Examples 2
Produce citric acid according to EXPERIMENTAL EXAMPLE 3 described methods, different is, step (2) is under agitation, with in the 500L citric acid secondary and mother liquor (the pH value is 3, in Citric acid monohydrate Food grade, citric acid content is 2.5 % by weight, and temperature is 62 ℃) directly mix with 220kg solid carbonic acid calcium and react, mixing temperature is 62 ℃, is mixed with the calcium carbonate serosity that concentration is 45 % by weight; The solid-liquid volume ratio of citrate of lime slurries is 7: 3 in the step (3); In the step (4), with washing from the beginning calcium hydrogen citrate, the consumption of tap water is 3 tons of/ton citric acids; In the step (5), acidolysis obtains Aoidolysed lemon liguor, and the easy carbon multiple of calcium hydrogen citrate acid hydrolysis solution sees Table 1.And be 94.3% according to the yield that the formula of EXPERIMENTAL EXAMPLE 1 calculates citric acid.
Table 1
| Embodiment and Comparative Examples numbering | The easy carbon multiple of calcium hydrogen citrate acid hydrolysis solution |
| Embodiment 1 | 2.82 |
| Embodiment 2 | 2.81 |
| Embodiment 3 | 2.78 |
| Comparative Examples 1 | 2.85 |
| Comparative Examples 2 | 2.84 |
Having used the citric acid content that obtains citric acid fermentation aqueous solution behind the calcium hydrogen citrate washes in embodiments of the invention 3 is 12 % by weight; And using tap water to replace calcium hydrogen citrate washes in the Comparative Examples 1, the citric acid content that obtains citric acid fermentation aqueous solution is 11.7 % by weight.Use as can be known calcium hydrogen citrate washes that the solid acid sludge is washed, can improve the citric acid content in the citric acid fermentation aqueous solution, thereby improve the yield of citric acid.
And, result by the citric acid yield can find out, adopt the yield of the citric acid that method of the present invention obtains to be higher than the yield of citric acid in Comparative Examples 1 and 2, this is owing to having used calcium hydrogen citrate washes washing solid acid sludge, citric acid in the calcium hydrogen citrate washes has obtained utilization, and use and to contain lemon aqueous acid (being preferably the citric acid mother liquor from the secondary neutralization) and be used for calcium carbonate and size mixing and also can reduce the molten damage of citric acid, improved the yield of citric acid.
In addition, when adopting calcium carbonate serosity of the present invention to prepare citric acid, the solid-liquid volume of the citrate of lime slurries that obtain is smaller, the citrate of lime particle is large, even, the particle of the calcium hydrogen citrate that is then made by citrate of lime is larger, tap water volume used when therefore, washing calcium hydrogen citrate is less.Thereby the easy charcoal multiple of calcium hydrogen citrate acid hydrolysis solution is lower.What of readily carbonizable substance content in the calcium hydrogen citrate finished product the easy charcoal multiple of calcium hydrogen citrate acid hydrolysis solution directly affect, the easy charcoal multiple of calcium hydrogen citrate acid hydrolysis solution is directly proportional with the readily carbonizable substance content in the calcium hydrogen citrate finished product, and readily carbonizable substance is an important quality index of final product quality, because the easy charcoal multiple of the acid hydrolysis solution of calcium hydrogen citrate is lower, illustrate that the readily carbonizable substance content in the calcium hydrogen citrate finished product that obtains is less, the quality product of the citric acid that therefore, obtains is better.
Claims (11)
1. the treatment process of a calcium hydrogen citrate washes, the waste water that described calcium hydrogen citrate washes produces for washing calcium hydrogen citrate solid, in Citric acid monohydrate Food grade, the content of citric acid is less than 1 % by weight in the described calcium hydrogen citrate washes, it is characterized in that, the method comprises described calcium hydrogen citrate washes is used for solid acid sludge after the washing citric acid fermentation broth solid-liquid separation.
2. method according to claim 1, wherein, the content of citric acid is the 0.5-0.9 % by weight in the described calcium hydrogen citrate washes.
3. method according to claim 1, wherein, with respect to 1m
3Citric acid fermentation broth, the consumption of described calcium hydrogen citrate washes is 0.1-0.4m
3
4. method according to claim 1, wherein, described calcium hydrogen citrate solid is that calcium salt method prepares the solid that obtains through solid-liquid separation in the citric acid process.
5. the preparation method of a citric acid, the method may further comprise the steps:
1) with the citric acid fermentation broth solid-liquid separation, obtain clear liquid and solid acid sludge, the solid acid sludge is washed, and the washing water after will washing and clear liquid obtained above merging, obtain citric acid fermentation aqueous solution;
2) citric acid in making citric acid fermentation aqueous solution is converted under the condition of citrate of lime and carries out the first contact reacts with the described citric acid fermentation aqueous solution of a part and calcium carbonate serosity, and the product after the first contact reacts carried out solid-liquid separation, obtain the solid phase citrate of lime;
3) with step 2) the solid phase citrate of lime that obtains and the described citric acid fermentation aqueous solution of another part carry out the second contact reacts citrate of lime is converted under the condition of calcium hydrogen citrate, and the product after the second contact reacts carried out solid-liquid separation, obtain in solid phase calcium hydrogen citrate and the secondary and mother liquor, and the solid phase calcium hydrogen citrate washed, collect and obtain the content of citric acid less than calcium hydrogen citrate washes and the calcium hydrogen citrate of 1 % by weight;
4) the calcium hydrogen citrate acidolysis that step 3) is obtained obtains citric acid;
It is characterized in that, it is described calcium hydrogen citrate washes that the solid acid sludge that obtains in the step 1) is washed used washing water; The compound method of described calcium carbonate serosity comprises: under agitation, the pH value is less than or equal to 4 the lemon aqueous acid that contains and carries out first with calcium carbonate and mix, obtain the pH value and be the mixture of 4.8-5.2, the described first time of mixing was not less than 5 minutes; The pH value is mixed for the mixture of 4.8-5.2 carries out second with calcium carbonate, obtain calcium carbonate serosity.
6. method according to claim 5, wherein, in the compound method of calcium carbonate serosity, the described first temperature of mixing is 40-80 ℃, the first time of mixing was 20-30 minute.
7. method according to claim 5, wherein, in the compound method of calcium carbonate serosity, the described pH value that contains the lemon aqueous acid is 1.5-4; In Citric acid monohydrate Food grade, the described content that contains citric acid in the lemon aqueous acid is the 1-5 % by weight.
8. method according to claim 5, wherein, in the compound method of calcium carbonate serosity, the pH value is the 30-50 % by weight for the consumption of the mixture of 4.8-5.2 and calcium carbonate makes the solid content of calcium carbonate in the calcium carbonate serosity that obtains.
9. method according to claim 5, wherein, in the compound method of calcium carbonate serosity, the described lemon aqueous acid that contains is in the secondary that obtains in the step 3) and mother liquor.
10. method according to claim 5, wherein, in step 2) in, the described first catalytic condition comprises that the pH value of reaction end is 4.5-5.4, and temperature of reaction is 70-85 ℃, and the reaction times is 0.5-1.5 hour.
11. method according to claim 5, wherein, in step 3), the described second catalytic condition comprises that the pH value of reaction end is 2-4, and temperature of reaction is 70-80 ℃, and the reaction times is 2-3 hour.
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