Leaching of Turkish Oxidized Pb–Zn Flotation Tailings …
465
Formic Acid (FA) Leach
Leaching with FA at 1.0 M concentration at 40, 60, and 80 °C was performed at
S/L: 1/10 ratio. For 40 °C leaching temperature, at 30 min leaching time 62%, and
at 120 min leaching time, 78% Zn dissolution was obtained. At 180 min leaching
time, Zn dissolution was 76%. Metal dissolution order was Zn > Pb > Fe. Solution
pH changed between 2.8 and 3.0 with formic acid (Table 9). For 60 °C leaching temperature, Zn dissolution increased with increasing leaching time from 74 to 83% at
2.8% Pb co-dissolution. Solution pH was around 3.0. At 80 °C leaching temperature,
Zn dissolution increased from 76 to 82% at 4.3% Pb co-dissolution with increasing
leaching time from 30 min to 180 min Solution pH was around 3.0. FA achieved
maximum 83% Zn dissolution with 3% Pb and without Fe co-dissolution at 60 °C
leaching temperature using 1.0 M FA which seems to be selective to only dissolve
Zn without Fe and Pb co-dissolutions.
Malic Acid (MA) Leach
Metal dissolutions with 1.0 M MA at 80 °C and 1/10 S/L ratio were given in Fig. 5.
Metal dissolution order was Zn > Pb > Fe. Zn and Pb dissolutions were 72.1 and
13.3%, respectively, at 30 min leaching time. 91.6% Zn and 8.1% Pb dissolutions
were achieved at 180 min leaching time. 6.4% Fe co-dissolution was maximum at
180 min leaching time. Zn dissolution increased from 30 min to 180 min leaching
time. While there was a maximum at 30 min for Pb dissolution, Fe dissolution
increases with time up to 6.5% at 180 min pH of the leach medium increased from
2.04 at 30 min to 2.39 at 180 min. The dissolution selectivity difference between Zn
and Pb was 84% and between Zn and Fe was 85% at 180 min.
Ascorbic Acid (AA) Leach
The effects of 1.0 M ascorbic acid at 60 °C and 1/10 S/L ratio on metal dissolutions
were determined. Metal dissolution order is Zn > Fe > As > Pb > Ag. As the leaching
time increases Zn dissolution increased up to 34% at 60 min leaching time and then
slightly decreased to about 30% at 180 min. There is a slight increase in Fe, As, and
Pb co-dissolutions with increasing leaching time. pH of the leach solution changed
from 3.5 to 3.7 with increasing leaching time from 30 min to 180 min. At 1.0 M AA
dosage, Zn dissolution was very low and selectivity between Zn and impurity metals
for our purposes.
465
Formic Acid (FA) Leach
Leaching with FA at 1.0 M concentration at 40, 60, and 80 °C was performed at
S/L: 1/10 ratio. For 40 °C leaching temperature, at 30 min leaching time 62%, and
at 120 min leaching time, 78% Zn dissolution was obtained. At 180 min leaching
time, Zn dissolution was 76%. Metal dissolution order was Zn > Pb > Fe. Solution
pH changed between 2.8 and 3.0 with formic acid (Table 9). For 60 °C leaching temperature, Zn dissolution increased with increasing leaching time from 74 to 83% at
2.8% Pb co-dissolution. Solution pH was around 3.0. At 80 °C leaching temperature,
Zn dissolution increased from 76 to 82% at 4.3% Pb co-dissolution with increasing
leaching time from 30 min to 180 min Solution pH was around 3.0. FA achieved
maximum 83% Zn dissolution with 3% Pb and without Fe co-dissolution at 60 °C
leaching temperature using 1.0 M FA which seems to be selective to only dissolve
Zn without Fe and Pb co-dissolutions.
Malic Acid (MA) Leach
Metal dissolutions with 1.0 M MA at 80 °C and 1/10 S/L ratio were given in Fig. 5.
Metal dissolution order was Zn > Pb > Fe. Zn and Pb dissolutions were 72.1 and
13.3%, respectively, at 30 min leaching time. 91.6% Zn and 8.1% Pb dissolutions
were achieved at 180 min leaching time. 6.4% Fe co-dissolution was maximum at
180 min leaching time. Zn dissolution increased from 30 min to 180 min leaching
time. While there was a maximum at 30 min for Pb dissolution, Fe dissolution
increases with time up to 6.5% at 180 min pH of the leach medium increased from
2.04 at 30 min to 2.39 at 180 min. The dissolution selectivity difference between Zn
and Pb was 84% and between Zn and Fe was 85% at 180 min.
Ascorbic Acid (AA) Leach
The effects of 1.0 M ascorbic acid at 60 °C and 1/10 S/L ratio on metal dissolutions
were determined. Metal dissolution order is Zn > Fe > As > Pb > Ag. As the leaching
time increases Zn dissolution increased up to 34% at 60 min leaching time and then
slightly decreased to about 30% at 180 min. There is a slight increase in Fe, As, and
Pb co-dissolutions with increasing leaching time. pH of the leach solution changed
from 3.5 to 3.7 with increasing leaching time from 30 min to 180 min. At 1.0 M AA
dosage, Zn dissolution was very low and selectivity between Zn and impurity metals
for our purposes.