| 摘要 |
<p>PROBLEM TO BE SOLVED: To reduce residues and make them harmless by specifying the pH of respective solutions before electrolysis in a process of dissolving iron manufacturing dust by an acid, filtering the dissolution residues and then electrolysing filtrate, elctrolytically precipitating a heavy metal mainly composed of lead and recovering the same and also electrolysing an electroytic solution after electrolysis and electrolytically precipitating iron and recovering the same. SOLUTION: In the case of wet disposal of dust (iron manufacturing dust) generated in an iron mill, first the iron manufacturing dust is dissolved by an acid in a dust dissolving process, and dissolution residues are filtered and removed in a filtering process, and the pH of filtrate is adjusted to 0.5-3. Then the filtrate is electrolysed in a lead decomposing process, and a heavy metal composed mainly of dissolved lead in the filtrate is electrolytically precipitated and recovered, and the iron ions in the filtrate are reduced from trivalence to bivalence. Then the pH of the electrolytic solution after electrolysis is adjusted to 4-7 in a pH adjusting process, and then the electrolytic solution is electrolysed in an iron decomposing process, and the iron in the electrolytic solution is electrolytically precipitated and recovered, while zinc ions are made to remain in the electrolytic solution.</p> |
