Bismuth removal from molten lead - using mixt. of calcium-magnesium alloy granules, pref. of eutectic compsn.

摘要

Bismuth is removed from molten lead by addn. of calcium and magnesium in the form of a mixt. of Ca-Mg alloy granules. The mixt. pref. has an overall Mg content of 50-80 (pref. 55-75)% (by wt. of Ca+Mg) and pref. consists of a homogeneous mixt. of Ca-rich alloy granules contg. 10-35 (pref. 18) wt.% Mg and Mg-rich granules contg. 5-25 (pref. 16) wt.% Ca. Each alloy pref. has a m.pt. of less than 600 (pref. less than 550) deg.C. The Ca and Mg required for reaction are in a form in which they melt at the temp. of the molten Pb bath (usually 520-600 deg.C) and dissolve rapidly in the bath.