EXTRACTION OF OXALIC ACID FROM INDUSTRIAL FERRIC OXALATE Russian patent published in 2020 - IPC C07C55/06 C07C51/48 C07C51/02 

FIELD: technological processes.

SUBSTANCE: invention describes a method of extracting oxalic acid used in industrial ferrous metal etching processes. Method of extracting oxalic acid from ferric oxalate formed in industrial ferrous metal etching processes comprises I) adding an aqueous suspension of said ferric oxalate to an acid-resistant reactor with the possibility of mixing and controlling temperature; II) mixing a predetermined amount of concentrated sulfuric acid with the suspension mentioned in step I) and holding the mixture while stirring for a time sufficient for complete reaction to form a suspension from a solution of oxalic acid and solid monohydrate of ferrous sulfate, wherein temperature of reaction mixture increases due to reaction heat, where total amount of added sulfuric acid corresponds to mass fraction in percentage of 40 to 55 %; III) filtering the suspension obtained in step II) to separate ferrous sulfate monohydrate from the filtrate, said solution being said solution of oxalic acid; IV) cooling said filtrate while stirring, wherefrom oxalic acid is crystallized and precipitated therefrom, and V) separation, washing and drying of the precipitated oxalic acid.

EFFECT: method provides reduction of overall costs and environmental load from etching processes.

11 cl, 1 dwg, 3 ex