Patent ID: 6509179
Filing Date: 2003-01-21
Classification: C07C,C12P

Abstract:
Continuous process for preparing lactic acid, wherein the process comprises the following steps:(a) acidifying an aqueous feed [1], which has been obtained by fermentation and mainly contains lactate, with a stream [3] which mainly consists of lactic acid and a salt, (b) removing the salt from the aqueous stream [3] which mainly contains lactic acid and salt by means of filtration to form aqueous stream [4] which mainly contains lactic acid, (c) passing aqueous stream [4] which mainly contains lactic acid over a column containing activated carbon to form aqueous stream [5] which mainly contains lactic acid, (d) subjecting aqueous stream [5] which mainly contains lactic acid to a first extraction step, wherein aqueous stream [5] which mainly contains lactic acid is brought into contact with a substantially water-insoluble stream [6] which contains an extractant, to form a an organic phase [7] which mainly contains lactic acid and extractant and a first water phase [8] which mainly contains impurities, (e) subjecting the organic phase [7] which mainly contains lactic acid and extractant to a second extraction step, wherein the organic phase [7] which mainly contains lactic acid and extractant is brought into contact with an aqueous stream [9] to form a water phase [10] which mainly contains lactic and an organic phase [11] which mainly contains extractant, wherein the organic phase [11] which mainly contains extractant is recycled to step (d), and (f) concentrating the water phase [10] which mainly contain contains lactic acid by means of evaporation of water to form a concentrated lactic acid solution in water [12].