Leaching agent

Concentration (%)

Concentration in residue (%)

Dissolution (%)

SiO₂ (%)

Fe

Al₂O₃

Fe

Al₂O₃

HF/HCl

50/25

0.38

0.70

37.2

74.4

97.4

NaOH

10

0.28

0.66

18.7

6.91

97.8