As a general rule, alloys from tantalite, colum- bite or pyrochlore produced by aluminothermic or electrothermic processes are used. The conversion of the ferroalloy takes place according to the follow- ing formulas: FeNb + NaCl + 7 NaFeC14+ NbC15 + 8 NaFeC13 (2) (3) 8 NaFeC13 + 4 C13 + 8 NaFeC14 NaFeC14 is used cated in Figure
![](/images/caleb/60.jpg)