Title:
PROCESS TO MAKE HARMLESS WASTE LIQUID CONTAINING HEXAVALENT CHROMIUM
Document Type and Number:
Japanese Patent JP3171912
Kind Code:
B2
Abstract:
PURPOSE: To reduce waste processing cost by processing to make harmless a waste liquid containing hexavalent chromium generated in a ferrous alloy steel strip manufacturing process with various waste liquids generated in the likewise ferrous alloy steel strip manufacturing process through their mutual processing using their respective specific qualities.
CONSTITUTION: Spent hydrochloric acid is added to a waste liquid 9 containing hexavalent chromium to reach the pH value ≤1, using the other waste liquid generated in a ferrous alloy steel strip manufacturing process. Further, an aqueous ferrous chloride solution 8 acidified to the pH value ≤1 by adding spent hydrochloric acid is added to the waste solution as a reduction agent which is prepared by adding iron scrap to the waste liquid. Consequently, the waste liquid 9 containing hexavalent chrominum whose pH value is thus adjusted is allowed to undergo a reduction process so that the oxide-reduction potential of the waste solution 9 is maintained within a range of 500±10mV for a reference electrode of silver chloride. After that, the waste liquid 9 containing hexavalent chromium is neutralized using spent alkali 13 so that the pH value of the waste liquid 9 is maintained within a range of 7 to 8. Finally, the neutralized waste liquid is separated into the solid and the liquid by using a centrifuge.
Inventors:
Issei Sakurai
Application Number:
JP6151292A
Publication Date:
June 04, 2001
Filing Date:
February 17, 1992
Export Citation:
Assignee:
Nisshin Steel Co., Ltd.
International Classes:
C02F1/70; (IPC1-7): C02F1/70
Domestic Patent References:
| JP360795A | ||||
| JP3137988A |
Attorney, Agent or Firm:
Tadayuki Noma