Recycling of Zinc from Galvanized Steel Scrap
823
Table 2 Stripping of zinc
Organic feed
(loaded LIX-26)
Aqueous feed
(H 2 SO 4 )
% Stripping of Zn
11.25 g/L Zn
pH = 1
90
10.08 g/L Zn
pH = 1.5
20
10.08 g/L Zn
pH = 2
8.38
10.08 g/L Zn
pH = 3
0.11
Precipitation of Zinc
Zinc was precipitated from strip solution as zinc carbonate. Precipitation test was
carried out at room temperature. A 100 mL of stripped solution containing 4.958 g/L
Zn was stirred with 1.3 g sodium carbonate powder for about 30 min. Complete
precipitation (99.92%) of zinc was taken place as zinc carbonate.
Reaction Scheme
Based on the experimental results the following reaction mechanism was derived,
where HQ represents the hydroxyquinoline extractant.
Leaching:
Zn + 2NaOH + 1/2O 2 → Zn(ONa) 2 + H 2 O
Extraction:
Zn(ONa) 2 → ZnO 2
2−
+ 2Na
+
ZnO 2
2−
+ 2HQ → ZnQ 2 + 2OH
−
2Na
−
+ 2OH
−
→ 2NaOH
Stripping:
H 2 SO 4 + ZnQ 2 → 2HQ + ZnSO 4
Precipitation:
ZnSO 4 + Na 2 CO 3 → ZnCO 3 + Na 2 SO 4