Background technology
Citric acid is a kind of organic acid that is widely used in industries such as beverage, food and medicine, and China is citric acid production big country, have 20 surplus family factory, output is above 500,000 tons.The extracting method of citric acid is mainly calcium salt method, chromatography, membrane separation process and extraction process both at home and abroad.
The shortcoming of tradition calcium salt method technology, the one, citric acid per ton consumes about 0.9 ton of sulfuric acid and 0.9 ton of lime carbonate, supplementary product onsumption height; The 2nd, produce about 2 tons of solid waste-calcium sulfate; The 3rd, citrate of lime throw out specific surface area is big, and absorption impurity is many, causes leaching requirement big, and hot water consumption is many, in and yield is the highest can only reach 94%, yield is low; The 4th, acidity is the highest after the citric acid acidolysis can only reach about 40%, concentrates the energy consumption height.
The shortcoming of chromatography technology, the one, equipment and off-set facility investment are high; The 2nd, the material pre-treatment is complicated, and consumption is big, cost is high.
Electrodialytic shortcoming, the one, equipment and off-set facility investment are high; The 2nd, power consumption height, production cost height.
The shortcoming of extraction process, the one, poor product quality; The 2nd, the residual product that causes of extraction agent can not be applied to food and pharmaceutical industries.
Therefore, need to seek a kind of method for extracting citric acid that improves yield, saving auxiliary material, reduces the calcium sulfate pollution.
Summary of the invention
The purpose of this invention is to provide a kind of method for extracting citric acid that improves yield, saving auxiliary material, reduces the calcium sulfate pollution.
In order to realize the object of the invention, the production method of a kind of citric acid of the present invention comprises the steps:
1) earlier adding lime carbonate and/or calcium hydroxide in the citric acid sterilization clear liquid are reacted, reaction end pH value is 3~9, separates waste water and obtains citrate of lime;
2) with citrate of lime and citric acid sterilization clear liquid reaction, regulating the pH value is 1.5~6, generates hydrogen citrate calcium and/or dihydrogen citrate calcium;
3) carry out solid-liquid separation and wash solid phase then, liquid phase is returned in the step 1, and solid phase is carried out acidolysis reaction, generates citric acid and calcium salt;
4) carry out solid-liquid separation at last and handle, the washing solid phase, liquid phase obtains citric acid through aftertreatment again.
Wherein, described citric acid sterilization clear liquid is that the fermented liquid of citric acid production carries out the clear liquid that gained is handled in degerming.
Temperature of reaction is 50~100 ℃ in the step 1).
Step 2) temperature of reaction is controlled at 20~100 ℃ in.
The washing solid phase adopts 20~100 ℃ water washing in the step 3).
Liquid phase is returned step 1, can separately or mix back adding lime carbonate and/or calcium hydroxide with citric acid sterilization clear liquid and neutralize, and discharges waste water, obtains citrate of lime and discharges impurity.
Used acid is sulfuric acid in the acidolysis reaction, and temperature of reaction is 70~90 ℃, and reaction end pH value is 1.5~3.
The washing solid phase adopts 20~100 ℃ water washing in the step 4).
Solid-liquid separation can adopt filtering type, decanter type or their combination.
Described aftertreatment is this area ordinary method, such as process decolouring, ion-exchange, condensing crystal, centrifugal and baking operation.
The production method of citric acid of the present invention, its advantage is:
1. water consumption is low: because of the hydrogen citrate calcium among the present invention and/or the crystallization of dihydrogen citrate calcium be the xln of rule, the crystal specific surface area is little, is easy to crystal and separate impurities, the very a spot of water of use during washing
2. yield height, waste water COD total amount reduce: at first, when producing citrate of lime, because of in having improved and the terminal point pH value, citrate content reduces significantly in the waste water.Secondly under the certain condition of citrate of lime solubleness, the waste liquid volume reduces, and the citrate of lime yield improves.Once more, because of the calcium sulfate generation reduces, the residual sour total amount of hydrolysis procedure calcium sulfate also reduces thereupon.
3. supplementary product onsumption is low: at first, there is not the acid consumption because of lime carbonate and/or the excessive generation of calcium hydroxide in hydrolysis procedure; Secondly, because of the material that enters hydrolysis procedure is hydrogen citrate calcium and/or dihydrogen citrate calcium, the supplementary product onsumption of unit citric acid product reduces more than 1/3rd.
4. the calcium sulfate generation is few, has reduced quantity of solid waste: the present invention is because of the reduction of lime carbonate and/or calcium hydroxide and sulfuric acid consumption, and byproduct calcium sulfate also decreases.
5. acid hydrolysis solution acidity height, save energy: the citrate of lime of equal in quality and hydrogen citrate calcium and/or dihydrogen citrate calcium are relatively, citric acid content height in hydrogen citrate calcium and/or the dihydrogen citrate calcium wherein, so more traditional calcium salt method height of acid hydrolysis solution concentration of the present invention, concentrate steam consumption and reduce, reduced production cost.
Embodiment
Following examples are used to illustrate the present invention, but are not used for limiting the scope of the invention.
Embodiment 1
The production method of citric acid comprises the steps:
1. earlier with 4m
3Acidity is that 11% citric acid sterilization clear liquid is put in the reactor, and feed temperature is heated to 80 ℃.
2. slowly add lime carbonate and carry out neutralization reaction, after the pH value is 5.0, stop to feed in raw material, left standstill 20 minutes, after the layering of question response liquid, supernatant effluent is discharged, obtain about 1m
3Pulpous state citrate of lime material.
3. citric acid sterilization clear liquid is slowly joined in the above-mentioned citrate of lime material, temperature of reaction is controlled at 85 ℃, and endpoint pH is controlled at 2.3.
4. the reaction solution that obtains of separating step 3, in returning after liquid phase is collected and in the operation reactor, can mix arbitrarily with clear liquid, solid phase is standby after with 50 ℃ water washing, solid phase is hydrogen citrate calcium and/or dihydrogen citrate calcium, and consumption acidity is 11% the about 2.5m of citric acid sterilization clear liquid
3
5. the solid phase that will wash 1.5 tons of the weight in wet bases in back in the acidolysis pot with 300 kilograms of strong sulfuric acid responses, temperature of reaction is 70 ℃, reaction end pH value is 1.8, generation citric acid and calcium sulfate.
6. separation of citric acid and calcium sulfate must citric acid concentration be 48% acid hydrolysis solution 1.295m after 50 ℃ of water washings
3
7. acid hydrolysis solution obtains the citric acid product after operations such as decolouring, ion-exchange, concentrated, centrifugal, oven dry.
Embodiment 2
The production method of citric acid comprises the steps:
1. react liquid phase (liquid phase of step 4) second time that embodiment 1 is produced and mix post-heating to 50 ℃ with citric acid sterilization clear liquid.
2. slowly add lime carbonate, after the pH value is 9.0, stop to feed in raw material, and separate part waste water.
3. citric acid sterilization clear liquid is slowly joined in the above-mentioned pasty material, temperature of reaction is 100 ℃, and the terminal point pH value is controlled at 6.0.
4. the reaction solution that obtains of separating step 3, in returning after liquid phase is collected and operation, and 20 ℃ adding water washing solid phase, solid phase is a hydrogen citrate calcium.
5. solid phase generates calcium sulfate and citric acid with strong sulfuric acid response in the acidolysis pot, and temperature of reaction is controlled at 90 ℃, and reaction end pH value is controlled at 2.2.
6. separate above-mentioned reaction solution, and, obtain citric acid acidolysis liquid with 20 ℃ of water washing solid phases.
Embodiment 3
The production method of citric acid comprises the steps:
1. react liquid phase (liquid phase of step 4) second time that embodiment 2 is produced and mix post-heating to 100 ℃ with citric acid sterilization clear liquid.
2. slowly add lime carbonate, add calcium hydroxide and regulate pH value to 6.5 after the pH value is 4.0, reaction finishes back separate part waste water.
3. citric acid sterilization clear liquid is slowly joined in the above-mentioned pasty material, temperature of reaction is 20 ℃, and endpoint pH is controlled at 3.0.
4. the reaction solution that obtains of separating step 3, and add the water washing solid phase is in returning after liquid phase is collected and operation.
5. solid phase generates calcium sulfate and citric acid with strong sulfuric acid response in the acidolysis pot, and temperature of reaction is controlled at 80 ℃, and the reaction end pH value is controlled at 1.5.
6. separate above-mentioned reaction solution, and, obtain citric acid acidolysis liquid with 80 ℃ of water washing solid phases.
7. acid hydrolysis solution obtains the citric acid product after operations such as decolouring, ion-exchange, concentrated, centrifugal, oven dry.
Embodiment 4
The production method of citric acid comprises the steps:
1. react liquid phase the second time that embodiment 3 is produced and mix post-heating to 70 ℃ with citric acid sterilization clear liquid.
2. slowly add calcium hydroxide, regulate pH value to 7.0, reaction finishes back separate part waste water.
3. citric acid sterilization clear liquid is slowly joined in the above-mentioned pasty material, temperature of reaction is 90 ℃, and endpoint pH is controlled at 1.5.
4. the reaction solution that obtains of separating step 3, and add the water washing solid phase is in returning after liquid phase is collected and operation.
5. solid phase generates calcium sulfate and citric acid with strong sulfuric acid response in the acidolysis pot, and temperature of reaction is controlled at 90 ℃, and the reaction end pH value is controlled at 3.0.
6. separate above-mentioned reaction solution, and, obtain citric acid acidolysis liquid with 20 ℃ of water washing solid phases.
7. acid hydrolysis solution obtains the citric acid product after operations such as decolouring, ion-exchange, concentrated, centrifugal, oven dry.
Embodiment 5
The production method of citric acid comprises the steps:
1. react liquid phase the second time that embodiment 4 is produced and mix post-heating to 90 ℃ with citric acid sterilization clear liquid.
2. slowly add lime carbonate, after the pH value is 5.5, stop to feed in raw material, and separate whole waste water.
3. citric acid sterilization clear liquid and citrate of lime are slowly joined in the another set of retort simultaneously, temperature of reaction is 100 ℃, and endpoint pH is controlled at 5.0.
4. the reaction solution that obtains of separating step 3, and add the water washing solid phase is in returning after liquid phase is collected and operation.
5. solid phase generates calcium sulfate and citric acid with strong sulfuric acid response in the acidolysis pot, and temperature of reaction is controlled at 70 ℃, and reaction end pH value is controlled at 1.8.
6. separate above-mentioned reaction solution, and, obtain citric acid acidolysis liquid with 100 ℃ of water washing solid phases.
7. acid hydrolysis solution obtains the citric acid product after operations such as decolouring, ion-exchange, concentrated, centrifugal, oven dry.
Embodiment 6
The production method of citric acid comprises the steps:
1. citric acid sterilization clear liquid is put in the reactor, and feed temperature is heated to 80 ℃.
2. slowly add lime carbonate, after the pH value is 5.0, stop to feed in raw material, and separate whole waste water.
3. citric acid sterilization clear liquid and citrate of lime are slowly joined in the another set of successive reaction jar simultaneously, temperature of reaction is 65 ℃, and pH value is controlled at 2.5.
4. the reaction solution that obtains of separating step 3, and add the water washing solid phase is in returning after liquid phase is collected and operation.
5. solid phase generates calcium sulfate and citric acid with strong sulfuric acid response in the acidolysis pot, and temperature of reaction is controlled at 90 ℃, and reaction end pH value is controlled at 2.2.
6. separate above-mentioned reaction solution, and, obtain citric acid acidolysis liquid with 50 ℃ of water washing solid phases.
7. acid hydrolysis solution obtains the citric acid product after operations such as decolouring, ion-exchange, concentrated, centrifugal, oven dry.
Though above the present invention is described in detail with a general description of the specific embodiments, on basis of the present invention, can make some modifications or improvements it, this will be apparent to those skilled in the art.Therefore, these modifications or improvements all belong to the scope of protection of present invention without departing from theon the basis of the spirit of the present invention.