1.Raw material workshop
The raw material will be grinded, adjusted to Liquefied liquid by enzymolysis for fermentation.
The fermentation of citric acid is Aerobic batch fermentation. As per the process requirement, urea will be added during the fermentation to supply carbon source and nitrogen source. The sterile air is input during fermentation too, and finally the fermentation mash which contains rich citric acid is generated.
Aspergillus niger is used to ferment the sugar liquor into citric acid liquor.
The liquefied liquor is used as the back material of the fermentation seed tank, after the high temperature sterilization, inoculation after cooling to get seed cultivation; the liquefied liquor, sugar liquor and nutrient substance will be going through pasteuring and cooling, to mix the seed from seed tank to fermentation tank, by controlling the dissolved oxygen and temperature, after 60 hours ferment cultivation, the fermentation will be finished.
Citric acid fermentation liquor has a process of “Calcium citrate continuous neutralization”, “Calcium hydrogen citrate continuous neutralization” and “Continuously acidolysis”, during these process, the solid-liquid separation all use Rubber belt vacuum filter. The qualified Acid solution goes to ion exchange process.
The fermentation liquor will be solid-liquor separated to remove acid sludge; then the liquor go through continuous neutralization and continuously acidolysis to generate acid solution, this procedure removed the impurities of fermentation.
Acid solution goes through cation and anion exchange, concentration,crystallization, centrifugation separation, drying, sieving and packing then become qualified citric acid anhydrous and citric acid monohydrate product.