456
M. Kaya et al.
of CA leaching tests were performed using 0.5 M CA concentration with 25 g Oreks
tails at S/L ratio of 1/10. The second group tests were carried out using 0.5 M CA
and 0.05 M NaCl. The third group tests were performed under the optimum Zn
dissolution results obtained from previous two tests at 1.0 M CA concentration to
further increase the Zn dissolution. Pulp temperature was 25, 40, and 60 °C. Leaching
time was 30, 60, and 120 min. At the end of leaching tests, one PLS solution was
also taken.
Table 3 shows metal dissolutions with 0.5 M citric acid at 1/10 S/L ratio and
400 rpm at different leaching temperatures. Zn dissolution always increased with
increasing leaching time and temperature from 44 to 90%. At 25 °C leaching time,
Zn dissolution increased from 44 to 50%; at 40 °C, 50 to 61%; at 60 °C, 61 to
75%, and 80 °C 75 to 90% within the tested leaching times. Arsenic is the second
most co-dissolved metal up to 80 °C leaching temperature. Fe is the third most codissolved metal except for 25 °C. Pb is the least co-dissolved metal except for 25 °C
leaching temperature. As co-dissolved from 6.8% up to 14.4%, Fe co-dissolved
from 3.6% up to 17.4% and Pb co-dissolved from 4.2% up to 7%. Optimum Zn
Table 3 Metal dissolutions with 0.5 M CA at 1/10 S/L ratio and 400 rpm at different leaching
temperatures
Citric acid
Zn (%)
As (%)
Fe (%)
Pb (%)
Time
25 °C
0.5 M
1/10 S/L
400 rpm
30 min
44
6.8
3.6
4.2
60 min
47
7.2
4.0
4.4
120 min
50
7.9
4.3
4.6
Metal
Dissolution
Order
Zn > As > Pb > Fe
Time
40 °C
0.5 M
1/10 S/L
400 rpm
30 min
50.1
8.1
4.7
4.9
60 min
55.0
9.0
5.6
5.2
120 min
61.2
9.7
6.6
5.4
Metal
Dissolution
Order
Zn > As > Fe > Pb
Time
60 °C
0.5 M
1/10 S/L
400 rpm
30 min
60.7
10.4
7.7
5.8
60 min
67.7
11.6
9.6
6.0
120 min
74.7
12.7
11.5
6.3
Metal
Dissolution
Order
Zn > As > Fe > Pb
Time
80 °C
0.5 M
1/10 S/L
400 rpm
30 min
74.5
12.8
11.5
6.6
60 min
81.5
13.7
13.9
6.8
120 min
89.6
14.4
16.3
7.0
180 min
90.1
14.2
17.4
6.8
Metal
Dissolution
Order
Zn > Fe > As > Pb
M. Kaya et al.
of CA leaching tests were performed using 0.5 M CA concentration with 25 g Oreks
tails at S/L ratio of 1/10. The second group tests were carried out using 0.5 M CA
and 0.05 M NaCl. The third group tests were performed under the optimum Zn
dissolution results obtained from previous two tests at 1.0 M CA concentration to
further increase the Zn dissolution. Pulp temperature was 25, 40, and 60 °C. Leaching
time was 30, 60, and 120 min. At the end of leaching tests, one PLS solution was
also taken.
Table 3 shows metal dissolutions with 0.5 M citric acid at 1/10 S/L ratio and
400 rpm at different leaching temperatures. Zn dissolution always increased with
increasing leaching time and temperature from 44 to 90%. At 25 °C leaching time,
Zn dissolution increased from 44 to 50%; at 40 °C, 50 to 61%; at 60 °C, 61 to
75%, and 80 °C 75 to 90% within the tested leaching times. Arsenic is the second
most co-dissolved metal up to 80 °C leaching temperature. Fe is the third most codissolved metal except for 25 °C. Pb is the least co-dissolved metal except for 25 °C
leaching temperature. As co-dissolved from 6.8% up to 14.4%, Fe co-dissolved
from 3.6% up to 17.4% and Pb co-dissolved from 4.2% up to 7%. Optimum Zn
Table 3 Metal dissolutions with 0.5 M CA at 1/10 S/L ratio and 400 rpm at different leaching
temperatures
Citric acid
Zn (%)
As (%)
Fe (%)
Pb (%)
Time
25 °C
0.5 M
1/10 S/L
400 rpm
30 min
44
6.8
3.6
4.2
60 min
47
7.2
4.0
4.4
120 min
50
7.9
4.3
4.6
Metal
Dissolution
Order
Zn > As > Pb > Fe
Time
40 °C
0.5 M
1/10 S/L
400 rpm
30 min
50.1
8.1
4.7
4.9
60 min
55.0
9.0
5.6
5.2
120 min
61.2
9.7
6.6
5.4
Metal
Dissolution
Order
Zn > As > Fe > Pb
Time
60 °C
0.5 M
1/10 S/L
400 rpm
30 min
60.7
10.4
7.7
5.8
60 min
67.7
11.6
9.6
6.0
120 min
74.7
12.7
11.5
6.3
Metal
Dissolution
Order
Zn > As > Fe > Pb
Time
80 °C
0.5 M
1/10 S/L
400 rpm
30 min
74.5
12.8
11.5
6.6
60 min
81.5
13.7
13.9
6.8
120 min
89.6
14.4
16.3
7.0
180 min
90.1
14.2
17.4
6.8
Metal
Dissolution
Order
Zn > Fe > As > Pb