Production of Corn Ethanol
Corn ethanol is primarily produced in two ways: dry milling or wet milling.
Dry Milling
Dry milling is the first method of producing corn based ethanol. First, the starch is ground from the corn kernel into a dry, powdery meal. The meal is mixed with water to create a wet mash. Enzymes are added to the mash, converting it into dextrose. Ammonia is put in to feed the yeast that will be added later. The mash is then cooked at a high temperature to reduce bacteria levels. The mash is cooled for the transfer to fermenters.
In the fermenters, the yeast is added to the mash to begin the process of converting the sugar into ethanol and carbon dioxide. After 40 to 50 hours in the fermenters, the mash turns into alcohol, and goes into distillation columns where it's separated from waters and solids to make pure ethanol. The final product is mixed at a specific concentration with gasoline.
In the fermenters, the yeast is added to the mash to begin the process of converting the sugar into ethanol and carbon dioxide. After 40 to 50 hours in the fermenters, the mash turns into alcohol, and goes into distillation columns where it's separated from waters and solids to make pure ethanol. The final product is mixed at a specific concentration with gasoline.
Wet Milling
Wet milling is almost the same as dry milling, the only differences are the first few steps. Instead of being ground from the corn kernel, the starch is soaked in water for up to 48 hours to dilute sulfurous acid and to separate the corn into different components. The slurry goes through a series of grinders to separate the starch from the rest of the mixture. The starch is then taken to fermenters, and the same process is followed as for dry milling.