Leaching of Turkish Oxidized Pb–Zn Flotation Tailings …
461
Citric Acid (C 6 H 8 O 7 ) Leach in Presence of NaCl
The effects of 0.5 M CA and 0.05 M and 2.0 M NaCl mixtures on metal dissolutions
were determined. At 0.5 M CA and 0.05 M NaCl concentrations and 25 °C leaching
temperature, Zn dissolution was 41.6% at 30 min and 48.6% at 120 min Pb codissolution was 4.3% at 30 min and 5.3% at 120 min Fe co-dissolution was 6.4%
at 30 min and 7.9% at 120 min. As co-dissolution was 9.5% at 30 min and 11.3%
at 120 min (Table 7). As co-dissolution was again higher than both Fe and Pb with
CA+NaCl mixture addition. Metal extraction order changed as Zn > As > Fe > Pb
under these conditions for all tested temperatures. At the highest Zn extraction of 48.6,
11.3% As, 7.9% Fe, and 5.3% Pb were co-dissolved. Presence of NaCl decreased
the Zn dissolution from 49.6 to 48.6% and increased As co-dissolution from 7.9 to
11.3%, Fe co-dissolution from 4.3 to 7.9%, and Pb co-dissolution from 4.6 to 5.3%.
For our tails, NaCl addition to CA had negative effect on both Zn dissolution and
impurity co-dissolutions. Increasing leaching temperature to 40 and 60 °C increased
both Zn dissolution and As, Fe, and Pb co-dissolutions with increasing leaching
time. Maximum 74% Zn dissolution with 16.5% Fe, 15.9% As, and 7.5% Pb codissolutions at 60 °C for 120 min leaching time was achieved using 0.5 M CA +
0.05 M NaCl addition. Without NaCl addition, 74.7% Zn dissolution with 12.7% As,
Table 7 Comparison of metal dissolutions with CA in the presence and absence of NaCl at 1/10
S/L ratio
Citric acid + NaCl
Zn (%)
As (%)
Fe (%)
Pb (%)
0.5 M CA + 0.05 M NaCl
25 °C
1/10 S/L
400 rpm
30 min
41.6
9.5
6.4
4.3
60 min
45.0
10.0
7.0
4.8
120 min
48.6
11.3
7.9
5.3
Only 0.5 M CA
49.6
7.9
4.3
4.6
Metal
Dissolution
Order
Zn > As > Fe > Pb
0.5 M CA + 0.05 M NaCl 40 °C
1/10 S/L
400 rpm
30 min
49.1
11.5
8.3
5.6
60 min
53.0
13.0
10.0
6.0
120 min
58.4
14.2
11.3
6.5
Only 0.5 M CA
61.26
9.7
6.6
5.4
Metal
Dissolution
Order
Zn > As > Fe > Pb
0.5 M CA+ 0.05 M NaCl
60 °C
1/10 S/L
400 rpm
30 min
60 min
120 min
58.1
65.0
74.0
14.5
15.2
15.9
11.9
13.0
16.5
7.2
7.4
7.5
Only 0.5 M CA
74.7
12.7
11.5
6.3
Metal
Dissolution
Order
Zn > As > Fe > Pb
461
Citric Acid (C 6 H 8 O 7 ) Leach in Presence of NaCl
The effects of 0.5 M CA and 0.05 M and 2.0 M NaCl mixtures on metal dissolutions
were determined. At 0.5 M CA and 0.05 M NaCl concentrations and 25 °C leaching
temperature, Zn dissolution was 41.6% at 30 min and 48.6% at 120 min Pb codissolution was 4.3% at 30 min and 5.3% at 120 min Fe co-dissolution was 6.4%
at 30 min and 7.9% at 120 min. As co-dissolution was 9.5% at 30 min and 11.3%
at 120 min (Table 7). As co-dissolution was again higher than both Fe and Pb with
CA+NaCl mixture addition. Metal extraction order changed as Zn > As > Fe > Pb
under these conditions for all tested temperatures. At the highest Zn extraction of 48.6,
11.3% As, 7.9% Fe, and 5.3% Pb were co-dissolved. Presence of NaCl decreased
the Zn dissolution from 49.6 to 48.6% and increased As co-dissolution from 7.9 to
11.3%, Fe co-dissolution from 4.3 to 7.9%, and Pb co-dissolution from 4.6 to 5.3%.
For our tails, NaCl addition to CA had negative effect on both Zn dissolution and
impurity co-dissolutions. Increasing leaching temperature to 40 and 60 °C increased
both Zn dissolution and As, Fe, and Pb co-dissolutions with increasing leaching
time. Maximum 74% Zn dissolution with 16.5% Fe, 15.9% As, and 7.5% Pb codissolutions at 60 °C for 120 min leaching time was achieved using 0.5 M CA +
0.05 M NaCl addition. Without NaCl addition, 74.7% Zn dissolution with 12.7% As,
Table 7 Comparison of metal dissolutions with CA in the presence and absence of NaCl at 1/10
S/L ratio
Citric acid + NaCl
Zn (%)
As (%)
Fe (%)
Pb (%)
0.5 M CA + 0.05 M NaCl
25 °C
1/10 S/L
400 rpm
30 min
41.6
9.5
6.4
4.3
60 min
45.0
10.0
7.0
4.8
120 min
48.6
11.3
7.9
5.3
Only 0.5 M CA
49.6
7.9
4.3
4.6
Metal
Dissolution
Order
Zn > As > Fe > Pb
0.5 M CA + 0.05 M NaCl 40 °C
1/10 S/L
400 rpm
30 min
49.1
11.5
8.3
5.6
60 min
53.0
13.0
10.0
6.0
120 min
58.4
14.2
11.3
6.5
Only 0.5 M CA
61.26
9.7
6.6
5.4
Metal
Dissolution
Order
Zn > As > Fe > Pb
0.5 M CA+ 0.05 M NaCl
60 °C
1/10 S/L
400 rpm
30 min
60 min
120 min
58.1
65.0
74.0
14.5
15.2
15.9
11.9
13.0
16.5
7.2
7.4
7.5
Only 0.5 M CA
74.7
12.7
11.5
6.3
Metal
Dissolution
Order
Zn > As > Fe > Pb