Fine debismuthizing with calcium, magnesium and antimony

In order to achieve fine debismuthizing of lead bullion, the effects of temperature, adding amount of calcium and magnesium and antimony on the bismuth removal from lead bullion were investigated. The mechanism of debismuthizing was also discussed. The results show that when adding amounts of calcium and magnesium reach 0.112% and 0.395%, respectively, bismuth level of 0.001% (mass fraction) in the final lead is achieved at 330 °C, without the need for antimony addition. Maintaining addition amount of magnesium at 0.155%, when calcium addition amount is less than 0.09%, the concentration of peritectic reaction point, the bismuth concentration can be easily decreased to 0.001% by the following antimony treatment. But the effect of antimony treatment on debismuthizing gets bad if the calcium addition exceeds 0.09%.