| 摘要 |
PURPOSE:To inexpensively regenerate an aged zinc chromate soln. by simple treatment by oxidizing tervalent Cr in the soln. to sexivalent Cr with H2O2 and by blowing H2S into the soln. to precipitate and remove Zn ions. CONSTITUTION:An aged zinc chromate soln. is shifted to an oxidation vessel and heated, and after adding H2O2, the soln. is stirred to oxidize tervalent Cr in the soln. to sexivalent Cr. The soln. is fed to a hydrogen sulfide reaction vessel and adjusted to about 5pH by adding NaOH or the like, and H2S is blow to precipitate Zn ions in the soln. as ZnS. The soln. is then passed through a filter and returned to a chromate soln. tank. By this method the aged zinc chromate soln. can be regenerated to a zinc chromate soln. contg. no metallic impurity ions and exerting no unfavorable influence on the formation of a chromate film. |
