PICKLING-REGENERATION PROCESS AND METHOD FOR REGENERATION OF SPENT PICKLING SOLUTION Russian patent published in 2004 - IPC

FIELD: chemical acid pickling of metals resulting in formation of spent metal-containing pickling solutions and wash water, in particular, regeneration of volatile acids, such as hydrochloric, hydrofluoric, nitric acids, from spent pickling solutions and processing of resultant wastes.

SUBSTANCE: pickling-regeneration process involves pickling stage and stage of regeneration of spent pickling solutions containing volatile acids by thermal hydrolysis followed by absorption of exit acid gases, processing of exit acid gases remained after absorption process with alkaline and production of wash water. Wash water is boiled out to produce water and concentrate of volatile acid salts. Wash water is used as service medium and volatile acid salt concentrate is directed for processing purposes. Method involves neutralizing free acids; boiling out to produce water; providing thermal hydrolysis; separating resultant solid substances; absorbing acid gases released during thermal hydrolysis; processing exit acid gases remained after absorption process with alkaline; providing exit of wash water.

EFFECT: provision for drain-free cycle, simplified construction of regeneration apparatus, increased corrosion resistance of equipment used, prolonged service life, reduced power and material consumption.

5 cl, 1 dwg, 3 ex