| 摘要 |
<p><P>PROBLEM TO BE SOLVED: To provide a method for recovering metals from neutralized sludge or neutralized slurry by which metals in two groups, i.e., a mixture composed mainly of Fe compounds and Cr compounds and a mixture composed mainly of Ni compounds and Zn compounds suitable for recycling, can be separately recovered from the neutralized sludge or the neutralized slurry both containing Fe and Cr and Ni and/or Zn and the separation and the recovery is carried out at a low treatment cost while minimizing the frequency of pH adjustment. <P>SOLUTION: The pH value of the neutralized sludge or neutralized slurry is adjusted to pH≤10 in two stages, desirably to pH 4 to 6 and then to pH 8 to 10, to separate and recover the Fe and Cr compounds and the Ni and Zn compounds. Moreover, by controlling the value of (Fe<SP>2+</SP>concentration)/(Ni<SP>2+</SP>concentration), the addition of waste acid at the pH adjustment is made possible. <P>COPYRIGHT: (C)2003,JPO</p> |
