• Crushing

  • Cleaned corn, after impurities are removed and metered, is sent to the hammer mill for crushing.

  • Then, it goes to the rotary vibration screen.

  • After screening, it is stored in tanks. Particle size of corn flour: ≤30% through 60 mesh screen underflow.

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• Adjusting

  • Water is added to adjust the flour slurry to DS=28-32%.

  • The metered flour slurry is sent to the pH adjusting tank with NaON solution and enzyme addition.

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• Liquefaction

  • Qualified corn flour slurry is sent to the 1st jet cooker and then to the liquefaction column for starch gelatinization and liquefaction.

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• Saccharification

  • Liquefied liquor goes to the second jet cooker for enzyme deactivation and protein agglomeration.

  • It is then sent to saccharification tanks to achieve the required DE after cooling and enzyme addition.

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• Filtration

  • After liquefaction, coarse protein is filtered from saccharified liquid using a filter press.

  • The filtrate proceeds to the next section, and coarse protein is dried in a dryer.

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• Seed Production

  • Part of the saccharified liquid is sent to the seed tank for adjusting DS value and pH, sterilization, cooling, and bacterial growth.

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• Fermentation

  • Filtrate is sent to the fermentation tank to adjust DS value and pH, sterilize, and cool to 35°C.

  • Strain is added to the fermentation tank through sterilized piping for fermentation with continuous sterile air feeding.

  • Fermentation is complete when residual glucose is less than 1g/L.

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• Pre-filtration

  • Besides citric acid, impurities such as mycelium are filtered out to ensure citric acid quality.

  • Washed mycelium is sold for feed production, and filtrate is used for the 1st neutralization.

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• 2nd Filtration

  • After pre-filtration, fine impurities are further removed to ensure clear and transparent filtrate.

  • Filter cake is washed, and filtrate is used for the 2nd neutralization.

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• 1st Neutralization

  • CaCO3 is added to thin citric acid to obtain Ca3(C6H5O7)2•4H2O sediment.

  • Sediment is filtered using a vacuum filter, and filtrate is wastewater to ETP.

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• 2nd Neutralization

  • Ca3(C6H5O7)2•4H2O sediment is adjusted and reacted with filtrate from the 2nd filtration to obtain CaH(C6H5O7)•3H2O sediment.

  • Sediment is filtered using a vacuum filter, and filtrate is used for the 1st neutralization.

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• Acidification

  • CaH(C6H5O7)•3H2O sediment, after adjustment, reacts with H2SO4 to produce citric acid (C6H8O7) and CaSO4.

  • CaSO4 is filtered out using a belt vacuum filter for gypsum production, and citric acid proceeds to the next section.

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• Decolorization and Filtration

  • Active carbon is added to citric acid for decolorization before proceeding to the next refining section.

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• Ion Exchange

  • Filtrate from the previous section is sent to ion exchangers to remove cations, anions, bad odors, and soluble impurities to obtain refined citric acid.

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• Monohydrate Citric Acid Evaporation

  • Citric acid, after passing through a check filter, is sent to an evaporator to achieve a higher DS value product.

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• Monohydrate Citric Acid Crystallization

  • Qualified citric acid monohydrate (CAM) from evaporation is crystallized and held for a specific time before moving to the refining section.

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• Anhydrous Citric Acid Crystallization

  • Anhydrous citric acid (CAA) from evaporation is sent to a forced circulation evaporating crystallizer to obtain crystals.

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• Separation

  • Crystallized CAM and CAA are sent to a separator to separate the mother liquid, resulting in qualified wet products for the next section.

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• Drying & Sieving

  • Wet product goes through drying and vibration sieving to obtain dried and qualified product.