Lactic acid extraction and purification production method by methanol esterification-vacuum distillation hybrid method

A lactic acid extraction and purification production method by methanol esterification-vacuum distillation hybrid method comprises steps of acidolysis and filtration, first concentration, secondary concentration, esterification and free water fractionation, feed liquid esterification and methyl lactate distillation, hydrolysis and methanol distillation recovery, concentration, two-stage short-path vacuum distillation and the like for actic acid extraction and purification. In particular, two short-path evaporators with multiple heating areas are installed in series for vacuum distillation so as to obtain the lactic acid product of good quality, which is better than the national standard of food additicve lactic acid. The comprehensive yield reaches over 90%; the steps are simple; and the production efficiency is greatly raised.