A E Staley Manufacturing Company

David Heidel

Avraham Baniel

Michael Charles Milner Cockrem

Istvan Kovacs

Idris Mohamednur

Asher Vitner

David Gonen

The invention provides a process for the recovery of citric acid from an aqueous solution feed stream originating in fermentation of carbohydrates and utilizing an amine solvent extraction step for separation of impurities comprising: subjecting said aqueous solution feed stream A to a treatment for partial recovery of citric acid, wherein said treatment is other than amine solvent extraction, to form a first portion of purified citric acid B and a secondary feed stream F; subjecting at least a portion G of said secondary feed stream F to a treatment consisting of amine solvent extraction to form a second portion of purified citric acid solution and to reject substantial of impurities initially present in said portion of said secondary feed stream; subjecting said second portion of purified citric acid solution to crystallization; and recycling mother liquor from said crystallization.

Process for the recovery of citric acid

A process is disclosed for purifying an aqueous feed stream comprising a product organic acid, such as lactic acid, and a strong contaminant, such as pyruvic acid or oxalic acid. The molar concentration of the product organic acid in the feed stream typically is at least 20 times greater than the molar concentration of the strong contaminant. The aqueous feed stream is contacted with a first immiscible basic extractant that has at least a 3-fold greater affinity for the strong contaminant than for the product organic acid. The majority of the strong contaminant and some product organic acid become complexed with the first immiscible basic extractant. The complexed first immiscible basic extractant is separated from the aqueous stream, thereby producing a first effluent stream that comprises product organic acid and that has a greater ratio of molar product organic acid to molar strong contaminant than the aqueous feed stream did. The complexed first immiscible basic extractant is contacted with a displacing acid. The first immiscible basic extractant has a greater affinity for the displacing acid than it does for the strong contaminant or the product organic acid, and as a result, product organic acid and strong contaminant are displaced over a period of time from the complexed first immiscible basic extractant, producing a second effluent stream that comprises a major amount of product organic acid and a third effluent stream that comprises a major amount of strong contaminant.

Process for purifying an organic acid

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Decatur, IL, United States of America

David Heidel