Process for producing starch sugar

The invention discloses a process for producing starch sugar. The process comprises the following steps of: pulp-conditioning edible starch; liquefying; passing liquefied starch through a primary floating clarifier, guiding an upper floating sugar dreg liquid into a primary buffer tank, and then entering a primary disc-type centrifuge to be centrifugated and separated so as to extract sugar dregs; combining a clear sugar liquid flowing out of the primary disc-type centrifuge and a clear sugar liquid flowing out of the primary floating clarifier and flowing into a saccharifying tank to be saccharified into a saccharified liquid; passing the saccharified liquid through a secondary floating clarifier, guiding an upper floating sugar dreg liquid into a secondary buffer tank, and then enteringa secondary disc-type centrifuge to be separated so as to extract sugar dregs; combining a clear sugar liquid flowing out of the secondary disc-type centrifuge and a clear sugar liquid flowing out ofthe secondary floating scum clearing device and filtering by passing through a membrane micro-filtration system; and flowing a micro-filtered concentrated liquid containing dregs back to the secondary buffer tank, entering a micro-filtered clear sugar liquid into an ion exchange system to be decolorized and desalted, and then finally concentrating into a product. According to the process for producing the starch sugar disclosed by the invention, filter aids and activated carbon are not required in the clarification and the filtration processes, and high-purity sugar liquid can be obtained through the efficient operation of solid-liquid separation equipment; and meanwhile, sugar dregs without the filter aids and the activated carbon are extracted and can be used as a feedstuff raw materialfor animals, thereby changing waste into valuable, and no discharge of filtered solid wastes during the whole process exists.