| 摘要 |
<p>Method for regenerating by crystallization on cooling pickling bath solutions based on sulphuric acid or hydrochloric acid and used for pickling iron, steel and other ferrous alloys. According to the invention the bath solution is regenerated in a combination of three stages. In a first stage acid is added to the solution in a concentration higher than the acid concentration of said solution, and the content of phosphoric acid is adjusted to be maintained between about 0.01 and 1 mole per litre solution, thereby to approach or to exceed the solubility of difficultly dissolved iron salts corresponding to the acid. In a second stage the solution is cooled, whereby iron salts precipitate. The cooling process is effected so as to reach a temperature at which the contents of iron and acid in the residual solution are suitable to permit said solution to be used again for pickling purposes. In a third stage the precipitated iron salt is removed from the solution, whereafter the regenerated pickling solution is returned for use at the pickling process. </p> |
