| 摘要 |
<p>PURPOSE:To enable production of Ca having much higher purity by subjecting again the residues made after CaO is subjected to pressure reduction thermal reduction by Al and high-purity Ca is won to the pressure reduction and thermal reduction by Al. CONSTITUTION:Al is added and mixed to and with CaO and the mixture composed thereof is put into a retort where the pressure is reduced to <=10<-3>Torr and the CaO is heated and is thus reduced to Ca. The Ca vapor made therefrom is then cooled and solidified to manufacture metallic Ca. MgO is contained in CaO as a raw material in this case and since Mg has the higher vapor pressure than Ca, MgO is preferentially reduced to Mg and enters the metallic Ca formed by entering the Ca vapor, thereby decreasing the purity thereof. The residues remaining after such reaction consist essentially of 3CaO.Al2O3 contg. substantially no MgO and therefore such residues are again subjected as a raw material to the pressure reduction and thermal reduction by Al, by which the metallic Ca of high purity contg. extremely little Mg is obtd.</p> |
