| Budget Amount *help |
¥3,800,000 (Direct Cost: ¥3,800,000)
Fiscal Year 2004: ¥1,100,000 (Direct Cost: ¥1,100,000)
Fiscal Year 2003: ¥2,700,000 (Direct Cost: ¥2,700,000)
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| Research Abstract |
Amount of metal residue from incinerators or melting furnaces of incinerator bottom ash has been increased in Japan. The metal residue contains valuable metals such as copper, silver and gold. Main components of the metal residue are copper, phosphorus, silicon and iron of the remainder. Copper content is 5 to 20% and too low to recover the valuable metals in a conventional copper smelter, so a new approach to upgrading the valuable metals with phase separation in molten metal system was researched. Whereas the binary melt of iron and copper is miscible over all composition, the addition of carbon or phosphorus to the binary melt leads to phase separation between an iron phase and a copper phase. The copper phase absorbing the precious metals is feasible for refining in a conventional copper smelter. Fundamental information about the phase separation, recovery of copper and distribution ratio of the valuable metals are presented.
Based on the mass-balance reaction and the solubility of copper in iron and iron in copper phases obtained in this study, copper recovery from the incineration metal residue containing iron and copper was calculated. Assuming that all copper in copper phase is recovered, and the copper dissolved in iron phase is loss, copper recovery is represented against copper grade in residue as shown in Fig. 8. When copper recovery by applying the phase separation of Cu-Fe-P system is carried out, copper recoveries from metal residues containing 10 and 30% copper are 35 and 80%, respectively. On the other hand, cooper recoveries with the phase separation of Cu-Fe-P-C system are 50 and 90% from metal residues containing 10 and 30% copper, respectively.
The distribution ratios of silver, gold, palladium, platinum and rhodium are listed in Table II. We can recognize the gold, silver and palladium are enriched in copper phase, on the contrary rhodium is more distributed to iron phase than to copper. Platinum is comparatively distributed to both phases.
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