Recovery of Lead from Zinc Plant Residue by Alkaline Leaching …
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Effect of Temperature
Effect of temperature (25, 40, and 50 °C) was examined with the purpose of reducing
the energy consumption in the Pb cementation. As can be seen in Fig. 8, the change
of temperature had no effect on the Pb cementation efficiency. At 25 °C and 30 min
of cementation time using 1.2:1.0 Zn:Pb mole ratio, 99.9% of cemented Pb could
be recovered with the purity of 97.6% (including 1.2% Zn as a major impurity).
Therefore, 25 °C can be fixed as the optimum temperature for the cementation.
The X-ray diffraction pattern illustrated in Fig. 9 indicates the product after cementation using Zn powder under the optimum cementation conditions. Only peaks
corresponding to Pb and PbO phases could be identified without any other impurities.
In order to examine the morphology and the trace impurities of the cemented Pb
product, SEM analysis has been conducted, and the images are shown in Fig. 10. The
uniform globules of lead particles with dark gray color can be clearly seen in Fig. 10a
Fig. 8 Effect of time on the
lead cementation in alkaline
media for 30 min (Zn:Pb
mole ratio = 1.2:1.0)
0
20
40
60
80
100
25
40
50
Cementation efficiency (%)
Solution temperature (°C)
Fig. 9 XRD pattern of lead
powders obtained from the
leach liquor of ZPR by
cementation using Zn
powder
(Time, 30 min; Zn:Pb mole
ratio = 1.2:1.0; temperature,
25 °C)
10
20
30
40
50
60
70
80
90
♦
♦
♦
♦
♦
♦
♦
♦
Cementation
∇
∇
∇
∇
∇
∇
∇
∇ - Pb
♦
♦
♦
♦
♦
♦
♦
♦
♦
♦
♦
♦
♦ − PbO
Intensity (a.u.)
Angle (2θ)