To reduce only Pb content with minimum reduction of Zn content by adding metallic Ca and/or Cu-Ca alloy in molten brass.
At the time of removing Pd as the compound with Ca by adding the metallic Ca and/or the Cu-Ca alloy into the molten brass containing Pd, it is confirmed that An content is scarcely changed. In such a case, the Ca is added so that the Ca concn. in the molten metal becomes ≥0.05 mass %. In the case of being <0.05 mass % Ca of added quantity, the compound of Pd is scaecely generated and there is no removal effect of Pd. Further, the temp. of the molten metal is made to ≤1200°C. This reason is because if this temp. exceeds 1203°C, the compound (Ca2Pb) of Pb and Ca starts to melt and the removal effect of Pb is lowered. Then, since the generated compound of Pb and Ca is very fine grains and the long time is necessary to float-up and separate, it is desirable to execute the filter treatment of the molten metal and the improvement of the removal efficiency in a short time can be obtd.
KUNII KAZUTAKA
OSUMI KENJI
OKADA HIROFUMI
YOSHIDA EIJI
MASUDA JOJI
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