Mechanism of debismuthizing with calcium and magnesium
(School of Materials and Metallurgy, Northeastern University, Shenyang 110819, China)
Abstract: In order to further understand the debismuthizing mechanism with calcium and magnesium, the influence of adding amount of calcium on the bismuth removal from lead was examined. A part of the debismuthizing dross samples were studied by electron probe microanalysis (EPMA). The results show that the calculated bismuthide governing debismuthizing process is Ca3Mg7Bi8, which may be a mixture of Ca3Bi2, CaBi, CaBi3 and Mg3Bi2. And the bismuthide formed during the debismuthizing process exists in two states: one is free bismuthide in the matrix of dross, and the other is symbiotic with Pb-Ca phase.
Key words: debismuthizing mechanism; Kroll-Betterton process; Ca3Mg7Bi8; Pb-Ca phase; Bi-Ca-Mg phase