Process for purifying citric acid mother liquor

Abstract

The invention discloses a process for purifying citric acid mother liquor, which comprises flocculation and separation, wherein flocculation treatment is to add a cationic polyacrylamide flocculant, of which the molecular weight is 12 million to18 million and of which the ion concentration is 40 to 55 percent, into mother liquor heated to a temperature below 20 DEG C in a ratio of 10 to 12 grams of flocculant per cubic meter of mother liquor with stirring; and 20 to 30 minutes later, stirring is stopped, the liquor is stood for settling, supernate of the mother liquor which is demixed after standing is extracted under vacuum and collected, the flocculated sediments are filtered out, and the filtrate is collected alone. In the invention, the need of diluting is obviated, the flocculation reaction is performed under a condition that the temperature is controlled to be below 20 DEG C, water is saved, the production cost is low, and the crystallization rate is improved considerably.

Description

technical field [0001] The invention belongs to the technical field of mother liquor treatment process in fermentation citric acid production, and in particular relates to a citric acid mother liquor purification treatment process. Background technique [0002] In the production of citric acid submerged fermentation, in addition to the main product, the fermentation liquid also contains some other metabolites, proteins, colloidal substances and other impurities. During the extraction process, most of these impurities are removed after filtration, adsorption and ion exchange, but some impurities will still enter the crystallization process of citric acid and remain in the crystallization mother liquor. Due to the high content of impurities in the mother liquor, it is difficult to effectively remove impurities such as proteins and colloids. At present, most manufacturers in the industry usually do not purify this part of the mother liquor, and some directly carry out concentr...

AI Technical Summary

Problems solved by technology

Although this method can effectively remove impurities in the mother liquor, there are disadvantages such as large consumption of raw materials and energy.

First, the mother liquor must be diluted to 20-70%. The water consumption is large in the early stage, and the crystallization energy consumption in the later stage is high, resource consumption is high, and the burden of pollution control is heavy.

The second is that the diluent needs to be heated to 20-65 degrees, which consumes a lot of energy; especially the mother liquor of citric acid monohydrate, its temperature is generally below 10 degrees, if it rises to 20-65 degrees, the energy consumption is huge

The third is to add coagulant and degumming agent to act together during the purification treatment. Not only the consumption of raw materials is high, but the processing cost is high, and the addition of these treatment agents will also increase the content of foreign impurities in the mother liquor and affect the quality of the mother liquor.

[0004] Under normal circumstances, the amount of citric acid mother liquor that needs to be processed accounts for 10% of citric acid. In these mother liquors, the citric acid content reaches more than 70%. If the mother liquor is not purified, it is difficult to continuously obtain qualified citric acid products. Reduced Yield and Production Benefits

Moreover, because citric acid fermentation is affected by raw materials and fermentation conditions, the amount of impurities produced during citric acid fermentation will also fluctuate, and the amount of citric acid mother liquor will sometimes be higher

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