To inexpensively and efficiently separating zinc in the zinc plating waste liquid from iron, and to produce high concentration zinc cakes of a zinc concentration of 40% or more which can be economically recycled.
The method includes: an air oxidation treatment step where the zinc plating waste liquid containing zinc ions of 10,000 mg/L or more and divalent iron ions of 3,000 mg/L is diluted up to 2-6 times by adding water therein, and where ferric hydroxide is precipitated after oxidizing the divalent iron ions into trivalent iron ions by adjusting a pH of the diluted waste liquid to 4.5-5.5 by adding alkaline thereto, and by blowing air; a first solid-liquid separation step where solid-liquid separation of the obtained treated liquid is performed; a pH adjustment treatment step where a pH of the obtained separated liquid is adjusted to 9.5 to 11 by adding alkaline (and/or sulfuration agent), and where zinc hydroxide (and/or zinc sulfide) is precipitated; a second solid-liquid separation step where solid-liquid separation of the obtained treated liquid is performed; and a zinc recovery step for recovering zinc compositions containing zinc of 40% or more per dry weight by cleaning the obtained solid matter.
TOMITA YOHEI
TSUJI TAKESHI
TSUCHIYA HIROSHI
OTANI AKEMI
JFE KANKYO CORP
| JP2002030352A | 2002-01-31 | |||
| JPS50110973A | 1975-09-01 | |||
| JPS62253738A | 1987-11-05 | |||
| JPH0259093A | 1990-02-28 | |||
| JPH04349990A | 1992-12-04 | |||
| JP2002126693A | 2002-05-08 |
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